production and use of short-lived radioisotopes from reactors

PRODUCTION AND USEOF

SHORT-LIVED RADIOISOTOPES

FROM REACTORS

I N T E R N A T I O N A L A T O M I C E N E R G Y A G E N C Y , V I E N N A 1 9 6 3

PRODUCTION AND USE OF SHORT-LIVED RADIOISOTOPES

FROM REACTORS

Since in many countries the new problems of producing, separating and applying short-lived radioisotopes are being faced for the first time, the IAEA convened an international Seminar on Practical Applications of Short-lived Radioisotopes produced in Small Research Reactors at its Vienna headquarters in November, 1962. More than 150 participants included reactor engineers and physicists, radiation chemists, industrial scientists, hydrologiste, physicians and agriculturists from 29 Member States. The present proceedings contain all the scientific papers submitted and the discussions

which followed them.

PRODUCTION ET EMPLOI DES RADIOISOTOPES DE

COURTE PÉRIODE OBTENUS DANS DES RÉACTEURS

Beaucoup de pays ont à résoudre, pour la première fois, les nouveaux problèmes que posent la production, la séparation et l'application des radioisotopes de courte période. C 'est pourquoi l'AIEA a organisé à son siège, à Vienne, en novembre 1962, des journées d'études sur les applications dee radioisotopes de courte période obtenus dans de petits réacteurs de recherche. Les participants, qui étaient plus de 150, comprenaient des spécialistes du génie et de la physique des réacteurs, des radiochimistes, des ingénieurs, des hydrologistes, des médecins et des agronomes, venant de 29 Etats Membres. Le présent ouvrage contient tous les mémoires scientifiques présentés et les discussions auxquelles

ils ont donné lieu.

ПОЛУЧЕНИЕ КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ В РЕАКТОРАХ

И ИХ ИСПОЛЬЗОВАНИЕ

Ввиду того, что во многих странах новые проблемы получения, разделения и применения короткоживущих радиоизотопов возникли впервые, Международное агентство по атомной энергии созвало в Центральных учреждениях в Вене в ноябре 1962 года международный семинар по практическому использованию короткоживущих радиоизотопов, получаемых в небольших исследовательских реакторах. В семинаре приняли участие свыше 150 специалистов из 29 государств-членов, среди которых были инженеры и физики-специалисты по реакторам, радиохимики, ученые, работающие в промышленности, гидрологи, врачи и агрономы. Настоящие труды содержат все представленные научные доклады и дискуссии по этим докладам.

APLICACIÓN DE LOS RADIOISÓTOPOS DE PERÍODO

CORTO PRODUCIDOS EN REACTORES

Teniendo en cuenta que son muchos los países en que se plantean por primera vez los problemas de la preparación, separación y utilización de los radioisótopos de periodo corto, el OIEA reunió en su Sede de Viena en el mes de noviembre de 1962 un seminario internacional sobre las aplicaciones prácticas de los radioisótopos de periodo corto, producidos en pequeños reactores de investigación. Hubo más de 150 participantes, entre ellos ingenieros y físicos nucleares, químicos especializados en los efectos de las radiaciones, técnicos industriales, hidrólogos, médicos y agrónomos, procedentes de 29 Estados Miembros. En el presente volumen se reproducen todos los documentos científicos que se presentaron y se reseñan los debates a

que dio lugar su examen.

PRODUCTION AND USE OF

SHORT-LIVED RADIOISOTOPES FROM REACTORS

VOL. I

The following States are Members of the International Atomic Energy Agency:

AFGHANISTANALBANIAARGENTINAAUSTRALIAAUSTRIABELGIUMBRAZILBULGARIABURMABYELORUSSIAN SOVIET SOCIALIST

REPUBLIC CAMBODIA CANADA CEYLON CHILE CHINA COLOMBIACONGO (LÉOPOLDVILLE)CUBACZECHOSLOVAK SOCIALIST REPUBLIC DENMARKDOMINICAN REPUBLICECUADOREL SALVADORETHIOPIAFINLANDFRANCEFEDERAL REPUBLIC OF GERMANYGHANAGREECEGUATEMALAHAITIHOLY SEEHONDURASHUNGARYICELANDINDIAINDONESIAIRANIRAQISRAEL

ITALYJAPANREPUBLIC OF KOREALEBANONLIBERIALUXEMBOURGMALIMEXICOMONACOMOROCCONETHERLANDSNEW ZEALANDNICARAGUANORWAYPAKISTANPARAGUAYPERUPHILIPPINESPOLANDPORTUGALROMANIASAUDI ARABIASENEGALSOUTH AFRICASPAINSUDANSWEDENSWITZERLANDTHAILANDTUNISIATURKEYUKRAINIAN SOVIET SOCIALIST REPUBLIC UNION OF SOVIET SOCIALIST REPUBLICS UNITED ARAB REPUBLIC UNITED KINGDOM OF GREAT BRITAIN AND

NORTHERN IRELAND UNITED STATES OF AMERICA URUGUAY VENEZUELA VIET-NAM YUGOSLAVIA

The Agency's Statu te was approved on 26 October 1956 a t an international conference held a t United Nations headquarters, New York, and the Agency cam e into being when the S tatute entered into force on 29 July 1957. The first session of the General Conference was held in Vienna, Austria, the perm anent seat o f the Agency, in October, 1957.

T he m ain objective o f the Agency is "to acce lera te and enlarge the contribution of atom ic energy to p eace , h ea lth and prosperity throughout the world".

Printed by the IAEA in Austria M arch 1963

PROCEEDINGS SERIES

PRODUCTION AND USE OF SHORT-LIVED RADIOISOTOPES

FROM REACTORS

VOL. I

PROCEEDINGS OF THE SEMINAR ON THE PRA CTICA L A PPLICATIO NS OF SHORT-LIVED RADIOISOTOPES

PRODUCED IN SMALL RESEARCH REACTORS HELD BY THE

INTERNATIONAL ATOMIC ENERGY AGENCY AT VIENNA, 5 - 9 NOVEMBER 1962

INTERNATIONAL ATOMIC ENERGY AGENCY VIENNA 1963

PRODUCTION AND USE OF SHORT-LIVED RADIOISOTOPES FROM REACTORS, IAEA, VIENNA, 1963

S T I/P U B /6 4

FOREWORD

T h e re a r e m an y ra d io iso to p e ap p lic a tio n s in w hich i t is im p o r ta n t th a t th e ra d ia t io n sh o u ld r a p id ly f a l l to an in s ig n if ic a n t le v e l once th e in i t ia l in te n se a c tiv ity h a s s e rv e d i t s p u rp o se . Such ap p lica tio n s inc lude d iag n o stic t e s t s in m e d ic in e , w h e re i t i s e s s e n t i a l to re d u c e th e r a d ia tio n d o se to th e p a tie n t to a m in im u m , n o n -d e s tru c tiv e te s tin g m ethods w hich m u s t be applied w ith o u t c o n ta m in a tin g th e m a te r ia l o r p ro d u c t c o n c e rn e d , and r e p e a te d ro u tin e t e s t s w hich a r e p o ss ib le only if th e re s id u a l ac tiv ity fro m the p rev io u s t e s t i s n e g lig ib le . A ll th e s e a p p lic a tio n s c a l l fo r r a d io n u c lid e s w hose h a lf- l iv e s a r e m e a s u re d in h o u rs o r ev en m in u te s . S im ila r ly , in th e new but in c re a s in g ly im p o r ta n t techn ique of ac tiv a tio n a n a ly s is , w hereby the q u an titie s of e le m e n ts p r e s e n t in a m a te r ia l can be d e te rm in e d by i r r a d ia t in g the m a te r i a l in a r e a c to r and a s s a y in g th e ra d io n u c lid e s p ro d u c e d , th e l a t t e r a r e m a in ly s h o r t - l iv e d and m u s t b e m e a s u r e d im m e d ia te ly .

W hile the p ro d u c tio n of lo n g -liv e d ra d io n u c lid e s ca n m o s t econom ica lly be le f t to th e l a rg e r e a c to r s a t th e m a in ra d io is o to p e c e n tr e s , s h o r t- l iv e d iso to p e s m u s t be p ro d u ce d , o r m a te r ia l s a c tiv a tio n p e r fo rm e d , in a r e a c to r a t o r n e a r th e p la c e of in ten d ed u s e o r a n a ly s is ; th is , th e n , r e p r e s e n ts one of th e m o s t im p o r ta n t u s e s fo r th e la r g e n u m b e r of s m a ll r e a c to r s w hich have b ee n in s ta l le d in r e c e n t y e a r s , o r w ill com e in to o p e ra tio n in th e n e a r fu tu re , in m an y p a r t s o f th e w o rld .

S ince in m any c o u n tr ie s the new p ro b le m s of p ro d u cin g , s e p a ra tin g and ap p ly in g s h o r t - l iv e d r a d io is o to p e s a r e b e in g fa c e d f o r th e f i r s t t im e , th e In te rn a tio n a l A tom ic E n e rg y A gency b e liev e d i t w ould be v a lu ab le to su rv e y th e s ta te of th e a r t by conven ing an in te rn a t io n a l S e m in a r on P r a c t i c a l A p p lic a tio n s of S h o r t- l iv e d R a d io is o to p e s p ro d u c e d in S m a ll R e s e a r c h R e a c to r s a t i t s V ien n a h e a d q u a r te r s in N o v e m b e r , 1962. T h is S e m in a r p ro v id e d an o p p o rtu n ity f o r th e p r o d u c e rs and u s e r s of s h o r t - l iv e d r a d io iso to p e s f ro m m a n y c o u n tr ie s to m e e t and d is c u s s th e p ro b le m s p re s e n te d b y th e s e new r e s e a r c h to o ls . T h e m o r e th a n 150 p a r t ic ip a n ts in c lu d e d r e a c to r e n g in e e rs and p h y s ic is ts , r a d ia t io n c h e m is ts , in d u s tr ia l s c ie n t is ts , h y d r o lo g is te , p h y s ic ia n s an d a g r i c u l tu r a l i s t s f ro m 29 M e m b e r S ta te s .

T he p r e s e n t p ro c e e d in g s co n ta in a l l the sc ie n tif ic p a p e rs su b m itte d and the d is c u s s io n s w hich fo llow ed th e m . T he w ide co v e ra g e of th e S em in a r in bo th the p h y s ic a l and the life s c ie n c e s i s in d ica tiv e of the m anifo ld u s e s of s h o r t - l iv e d r a d io is o to p e s . T h e i r p o te n t ia l i t i e s a r e o n ly j u s t b e g in n in g to be r e a l iz e d , and th e m a te r ia l in th e s e p ro c e e d in g s r e p r e s e n t s l i t t l e m o re th a n an in tro d u c tio n to w hat p r o m is e s to b ec o m e a v e r y b ig s u b je c t . I t i s hoped th a t i t w in b e found a v a lu a b le in tro d u c tio n .

M a rc h 1963SIGVARD EKLUND D ir e c to r G e n e ra l

EDITORIAL NOTE

The p a p e r s and d is c u s s io n s in c o rp o ra te d in the p ro c ee d in g s p u b lish ed b y the In te rn a tio n a l A to m ic E n e r g y A g e n c y a r e e d ited b y the A g e n c y 's e d ito r ia l s t a f f to the e x te n t c o n s id e re d n e c e s s a r y fo r the r e a d e r 's a ss is ta n c e . T h e v ie w s e x p r e s s e d and the g e n e r a l s t y l e a d op ted r e m a in , h o w e v e r , the r e s p o n s ib i l i t y o f the n a m e d a u th o rs o r p a r tic ip a n ts .

F o r the s a k e o f sp e e d o f p u b lica tio n the p r e s e n t P ro ce ed in g s have been p r in te d b y c o m p o sitio n typ in g and p h o to -o ffs e t lithography . W ithin the l im i ta tio n s im p o s e d b y th is m e th o d , e v e r y e f fo r t h a s b een m a d e to m a in ta in a h igh ed ito r ia l standard; in p a r tic u la r , the u n its and sy m b o ls em p lo yed are to the fu l l e s t p ra c tic a b le e x te n t th o se s ta n d a rd ize d o r re c o m m e n d e d by the c o m p e te n t in te rn a tio n a l s c ie n t i f ic b o d ie s .

The a ffi lia tio n s o f a u th o rs a re th o se g iven a t the tim e o f nom ination.The u se in th e se P ro ce ed in g s o f p a r tic u la r designa tions o f co u n tr ie s or

te r r i to r ie s does n o t im p ly any ju d g m en t b y th e A g en c y as to the leg a l s ta tu s o f su c h c o u n tr ie s o r te r r i to r ie s , o f th e ir a u th o r itie s and in s t i tu tio n s o r o f the d e lim ita tio n o f th e ir b o u n d a rie s .

T he m en tio n o f s p e c if ic co m p a n ies o r o f th e ir p ro d u c ts o r b ra n d -n a m es does n o t im p ly any e n d o rse m e n t o r re co m m en d a tio n on the p a r t o f the In te r n a tiona l A to m ic E n e r g y A g en cy .

CONTENTS OF VOL. I

I . PRODUCTION AND PREPARATION OF SHORT-LIVED RADIOISOTOPES

A re v ie w o f th e p ro d u c tio n o f " s p e c ia l" rad io iso to p es ............................................................................ 3L. G. S tang , Jr.

P ro d u c tio n o f s h o rt- l iv e d rad io iso topes ........................................................................................................ 31P .C . A e b e rso ld a n d A .F . Rupp

P ro je c t d 'u n e in s ta lla t io n d e tra i te m e n t c h im iq u e d e ra d io é lé m e n ts à co u rtes p é riodes . . . 49M . D ouïs e t f . V a lade

T h e p ro d u c tio n and d is tr ib u tio n o f s h o rt- l iv e d rad io iso to p es in th e U n ited K ingdom ........... 67C. T a y lo r , R. W est a n d M . W h iting

Производство короткоживущих радиоизотопов на реакторе ВВР-М .............................................. 83И.А. Кондуров и Д:А. Яшин•

H an d lin g and s e p a ra tio n o f s h o rt- l iv e d rad io iso to p es from re sea rc h re ac to rs ....................... .". 93W. W. M e in k e

P ro d u ctio n o f s h o r t- l iv e d ra d io n u c lid e s a t th e H a h n -M e itn e r In s titu te in W est B erlin ------ 105F. tv. F e lix , D . P irrw itz an d E , S z a b ó d e Bues

T h e S co ttish R esearch R eac to r C en tre and its fa c i l i t ie s for th e p ro d u c tio n and e x p lo ita tio no f sh o r t- l iv e d rad io iso to p es ......................................................................■...................................................... И ЗA . Ward

E xperiences w ith th e ir ra d ia tio n o f a m m o n iu m -b ro m id e ..................................................................... 123K . H e yd o m

C o n trib u tio n à l 'é tu d e d e la p ré p a ra tio n du t e l l u r e - 132 e t de l 'io d e -1 3 2 .................................... 141R. S t ie n n ó n -B ó v y e t G. R a e g e m a n -G e la d i

P ro d u cc ió n d e 'y o d o -1 3 2 a p a r tir d e .te tra tlu o ru ro d e u ran io irra d ia d o ........................................... 159M . B a rra ch în a -G S m e z

P ro d u c tio n of io d in e -1 3 2 fro m ir r a d ia te d te s t fu e l e le m e n ts .......................................................... 171H. S o ra n tin , H. T i t z e , H . B ild s te in an d N . G e to f f

II . PREPARATION AND APPLICATION OF SHORT-LIVED RADIOISOTOPES

A p p lic a tio n d e la d é s in té g ra tio n 132T e ê> 132I à la p ré p a ra tio n d e m o lé c u le s m arq u ées . . 181J .-P . A d l o f f e t M . A d lo ff-B a c h e r

S om e te c h n iq u es for is o la tin g and using sh o r t- l iv e d rad io iso to p es ................................................. 191F. N elso n a nd К . A . K raus,

P ro duction e t u ti l is a tio n des iso topes s o d iu m -2 4 , p o ta ss iu m -4 2 , c u iv re -6 4 e t m o ly b -d è n e -9 9 .................................................................................................................................................................... 215R. Loos

S h o r t- liv e d ra d io iso to p e p ro d u c tio n , p ro cess in g , d is trib u tio n and a p p lic a tio n s in K orea . . 221C hong K u k K im

II I . INDUSTRIAL APPLICATIONS

S h o r t- liv e d iso topes used as tra c e rs in in d u stry (w ith s p e c ia l re fe re n c e to Sw edish industry ) 229L . G. E rw all, H . G. Fors b erg an d K . L junggren

Stud ies w ith sh o r t- l iv e d rad io iso to p es in th e c h e m ic a l p rocess in d u s t r y ....................................... 249K . F m h a u f

Stud ies o f pow der m ix in g w ith sh o r t- l iv e d rad io iso to p es ..................................................................... 259I. B jer le a n d H . G. Forsberg

R ad io ac tiv e su rfa ce la b e ll in g o f pow dered m a te r ia ls by m ean s o f g o ld -1 9 8 ............................. 269B. R. P etersen

T e s t m e th o d fo r d e te rm in a tio n o f ca rb o n p a p e r tra n s fe r c h a r a c t e r i s t i c s ....................................... 275C. C. T h o m a s , Jr., R. F. H oran and D . M . H art

A p p lica tio n s d iv e rses des ra d io é lé m e n ts d e c o u rte p é r io d e dans l 'é tu d e des m é ta u x ............... 285A , K o h n

S e p a ra tio n o f im p u r itie s in th e z in c re c t i f ic a t io n p rocess by ra d io a c tiv e iso topes .................. 305К . А к е гт а п , М . B ra fm an , H . F ik , I . K ita la , M . N o w a k a n d A . P o c zyn a jto

T h e u se o f r e s e a rc h re a c to rs an d s h o r t- l iv e d iso to p es in th e s tu d y o f n u c le a r - re a c to r fu e lm a te r ia ls ....................... ............................................................................................................................................... 319T . S . E l le m a n , C . W . T o w n le y a n d D . N . S u n d erm a n

S o m e re c e n t a p p lic a tio n s o f sh o rt h a l f - l i f e ra d io iso to p e s in A u stra lia ........................................... 343T .S . W a n

Q u elq u es a p p lic a tio n s des ra d io é lé m e n ts à p é r io d e c o u rte dans l 'in d u s tr ie g a z iè refra n ç a ise ....................................................................................................................................................................... 357

C . T e ll ie r , G . C ourto is e t M . G asn ierA p p lic a tio n s du so d iu m -2 4 à des m esu res d e d é b its e t de re c h e rch e s d e fu ites .................... 333

J . G u iz e r ix e t R . C o m u e tE m p lo i du KN a c o m m e tra c e u r dans le s tra v a u x é d i l i ta i r e s e t h y d ro lo g iq u es ......................... 393

E. Gaspar, Л /. O n cescu , P. Sandra , L , G rigorescu , M . B irn b a u m e t T . T e ite l D e te rm in a tio n o f th e d is tr ib u tio n o f s ew a g e c o n c e n tr a tio n in la rg e n a tu ra l w a ters from

p la n n e d sew ag e o u tle ts ....................... ................................................................................................................. 405O . Berg a n d E . S o m e r

M esu re du po ids s p é c if iq u e d e l 'é m u ls io n ( e a u -v a p e u r ) s 'é c o u la n t dans un tu b e -é c ra nd e c h a u d iè re in d u s tr ie l le : e m p lo i d e so d iu m -2 4 ................................................................................. 415C . M a i l le , / , M o in a rd , D . B la n c e t j . Fon tan

List o f C h a irm e n a n d S e c re ta r ia t o f th e S e m in a r ............................................................................... 433

I

PRODUCTION AND PREPARATION OF SHORT-LIVED RADIOISOTOPES

A REVIEW OF THE PRODUCTION OF "SPECIAL" RADIOISOTOPES*

L. G. STANG. Jr.BROOKHAVEN NATIONAL LABORATORY, UPTON, NEW YORK,

UNITED STATES OF AMERICA

Abstract — Résumé — Аннотация — Resumen

A REVIEW OF THE PRODUCTION OF "SPECIAL" RADIOISOTOPES. Six useful characteristics o f rad io isotopes and advantages which m ay be taken of them are c ited briefly , with exam ples.

The Inform ation Sheet announcing this Sem inar listed four advantages o f short-lived over long -lived isotopes. Two other reasons why owners of sm all research reactors should concern themselves with short h a lf- life isotopes are econom y and particu lar su itab ility for production , the la tte r being due to th e pronounced effect of h a lf-life on the net ra te of production. Besides short h a lf-life , type and energy o f em itted radiation should be of concern to producers of isotopes.

Nine advantages of a nuclear reactor over a particle accelerator for radioisotope production are outlined.Following this general o rien ta tion , a survey of unusual or less frequently used production techniques

is presented. These include: (n ,p ) reactions and secondary reactions such as ( t ,n ) an d (t,p ) induced by thermal neutrons, various techniques for obtaining useful fluxes of fast neutrons with which to e ffec t other reactions, reco il techniques including classic Szilard-C halm ers reactions, use of charged wires to c o lle c t short-lived daughters of gaseous parents, parent-daughter milking system, parasitic irradiations, possible use of "knocked- on" protons or deuterons (from the moderator) as a means of êffecting reactions such as ( p , n ) , ( d ,n ) , e t c . , 'and the possible use of circulating "loops" in reactors with which to u tilize the radiation from ultra-short-lived radioisotopes such as A gi» , 1пШ , ш , D y * « n , e tc . Although not a production techn ique, the possibility of using certa in stable isotopes (e . g. of silver) as tracers which can be readily detected via subsequent a ctiv ation is mentioned.

Production figures for Brookhaven's ’’spec ia l" radioisotopes are cited to show differences in long - and short-term fluctuations among these isotopes, which are also com pared as a class to those in heavier demand supplied by Oak Ridge.

Present production methods of a ll "special" radioisotopes and tagged beads availab le from Brookhaven are reviewed very briefly , including recen t unpublished work concerned with the successful developm ent of an Al*8 "generato r", the production of Sc47, the increase in Mg28 specific ac tiv ity to 40 m c /g , and the use of Li*H* to e ffec t (n , partic le ) reactions.

LA PRODUCTION DE RADIOISOTOPES « SPÉCIAUX». L 'auteur c ite b rièvem ent, avec des exam ples à l'ap p u i, six caractéristiques utiles des radioisotopes e t le parti qu 'on peut en tirer.

La note d 'inform ation jointe â la le ttre qui annonçait la réunion du colloque énum érait quatre avantages des isotopes à courte période sur les isotopes à longue période. Les utilisateurs de petits réacteurs de recherche ont in té rê t à se consacrer aux isotopes I courte période pour deux autres raisons: ils sont plus économ iques e t ils conviennent m ieux pour la production , le taux n e t de c e l le - c i dépendant de la période. En plus de la longueur de la période, les producteurs d'isotopes devraient se préoccuper du type e t de l'énerg ie des rayonnements ém is.

L 'auteur énum ère ensuite neuf avantages du réacteur nucléaire sur l'accé lé ra teu r de particules pour la production de radioisotopes.

Après ces indications d 'o rd re g énéral, i l énum ère des m éthodes de production spéciales ou moins fréquem m ent u tilisées, notam m ent: les réactions (n , p) e t les réactions secondaires te lles que ( t ,n ) e t ( t , p ) produites par les neutrons therm iques, diverses techniques p e rm ettan t d 'o b ten ir dès flux u tiles de neutrons rapides à l’a ide desquels on provoque d 'au tres réactions, les techniques de recu l, no tam m ent les réactions classiques de Szilard -C halm ers, l'u tilisa tio n de fils chargés pour recueillir les produits de filiation à courte

* This paper was written and some of the work reported was performed under the auspices of the United States A tom ic Energy Commission.

3

4 L. G. STANG, JR.

période de radioisotopes gazeux , les systèmes de « m u l s i o n s pour séparer les produits de filia tio n des ascendants, les irradiations parasitaires, là possibilité d'em ployer des protons ou des deutérons «bom bardés (provenant du ralentisseur) pour provoquer des réactions te lles que (p ,n ) ( d ,n j e t c . , e t d* em ployer des « b o u c le s » de c ircu la tion dans les réacteurs qui perm ettra ien t d 'u tilise r les rayonnem ents provenant de radioisotopes à période u ltra -co u rte , tels que m , uein, lssmDy, e tc . Bien que ce ne soit pas unem éthode de production, l'au teu r indique la possibilité d 'u tilise r certains isotopes stables (par exam ple, de l'a rg en t) com m e indicateurs susceptibles d 'une détection a isée après activation .

I l c ite les chiffres de la production de radioisotopes « spéciaux » â Brookhaven e t indique les d ifférences de fluctuation â long term e e t à court term e pour ces isotopes, q u 'i l com pare en outre aux isotopes les plus dem andés fournis par Oak Ridge.

Les m éthodes actuelles de production de tous les isotopes «Spéciaux » e t b illes m arquées produites par Brookhaven sont exam inées très brièvem ent, y compris un trav a il récen t non encore pub lié concernant la mise qu point d'un «générateur » de 2eAl, la production de *7Sc, l'augm entation de l'ac tiv ité spécifique de »M g (portée â 40 m c/g) e t l'em ploi de eLi*H pour provoquer des réactions (n , particu le).

ОБЗОР ПРОИЗВОДСТВА "СПЕЦИАЛЬНЫХ" ИЗОТОПОВ. Перечисляется и иллюстриуются примерами шесть полезных свойств радиоизотопов и преимущества их использования.

В информационном листе этого семинара были приведены четыре преимущества короткоживущих изотопов по сравнению с долгоживущими. Двумя другими особенностями, благодаря которым владельцы небольших исследовательских реакторов больше заинтересованы в получении изотопов с малым периодом полураспада, являются экономичность и особое удобство при производстве, связанное с зависимостью скорости их накопления от периода полураспада. Помимо малого периода полураспада для производителей изотопов представляют интерес характер и энергия испускаемого излучения.

Приводятся в общих чертах девять преимуществ ядерного реактора по сравнению с ускорителями частиц.

В соответствии с этим общим направлением дается обзор необычных иди реже применяемых методов производства. Сюда включаются: реакции (п,р) и вторичные реакции, такие, как (t,n) и (t,p), вызванные тепловыми нейтронами, различные методы получения полезных потоков быстрых нейтронов, которые влияют на другие реакции, методы отдачи, включая классические реакции Сцидлард-Чалмерса, использование заряженных электродов для сбора короткоживущих дочерних продуктов газообразных исходных изотопов, системы непрерывного получения дочерних продуктов из материнских изотопов I"доение"), паразитное облучение, возможное использование "выбитых" протонов или дейтронов (из замедлителя) для проведения таких реакций, как (р,п), (d,n) и т.д. и возможное применение замкнутых "петель* в реакторах, с помощью которых используется излучение сверхкороткоживущих изотопов, таких, как Ag110 , In114 '116 , Dyic’5,n и т.д. Упоминается возможность использования, хотя и не в промышленных масштабах, некоторых стабильных изотопов (например, серебра) в качестве изотопных индикаторов, которые могут быть легко обнаружены и путем последующей активации.

Приводятся данные производства "специальных" изотопов в Брукхейвене, чтобы показать различия долговременных и кратковременных флуктуаций у этих изотопов, которые в совокупности также сравниваются с изотопами, поставляемыми из Окриджа, к корторыми предъявляются более высокие требования.

Дается очень краткий обзор современных методов производства всех "специальных" радиоизотопов и радиоактивных бус, получаемых из Брукхейвена, включая последние неопубликованные работы об успешном развитии "генератора" А128 , производстве Sc47 , увеличении удельной активности M g 28 до 40 милликюри/г и использовании L16H 2 для воздействия на реакции (п, частица).

PRODUCCION DE RADIOISOTOPOS "ESPECIALES". La m em oria c ita brevem ente seis características utile? de los radioisótopos y las ventajas que su u tilizac ión puede aportar, dando adem ás algunos ejem plos a l respecto.

La circular inform ativa que anunciaba la celebración del actual seminario enumeraba cuatro ventajas de los isótopos de período corto sobre los de peiíodo largo. Sería conveniente que los usuarios de pequeños reactores de investigación se ocuparan de los isótopos de período corto por dos motivos más: bajo costo y facilidad de obtenerlos, que se debe a l m arcado efecto del período de sem idesintegración sobre e l rendim iento neto. Los productores de isótopos deberían interesarse no sólo por e l período co rto , sino tam bién por e l tipo y la energía de las radiaciones que em iten .

A REVIEW OF THE PRODUCTION OF "SPECIAL" RADIOISOTOPES 5

La m em oria menciona nueve ventajas que, para la producción de radioisótopos, los reactores nucleares ofrecen sobre los aceleradores de partículas.

Después de estas observaciones de carácter general, la m em oria presenta un estudio de las técn icas de producción especiales o em pleadas menos frecuen tem ente . Entre e lla s , las reacciones (n ,p ) y reacciones secundarias com o las ( t , n) y ( t , p) inducidas por neutrones térm icos, diversas técn icas para obtener flujos útiles de neutrones rápidos en los que se inducen otras reacciones, técnicas por retroceso, incluyendo las re acciones clásicas tipo Szilard -Chalm ers, e l em pleo de alambre» cargados eléctricam ente para recoger descendientes de período corto de elem entos precursores gaseosos, procedimientos de separación repetida de precursores y descendientes, irradiaciones parásitas, e l posible uso de protones o deuterones percutidos (del moderador) como medio para producir reacciones de los tipos ( p .n ) , ( d ,n ) , e tc . ,y e lem p leo de los circuitos de un reactor para aprovechar las radiaciones em itidas por radioisótopos de período u ltracorto tales com o 114A g, n *In , lisin, usmDy, e tc . Aunque no se trata de una técnica de producción, se m enciona la posibilidad de u tilizar ciertos isótopos estables (por ejem plo, de la plata) como indicadores fáciles de detectar por activación ulterior.

El autor m enciona cifras de producción de los radioisótopos "especiales" en Brookhaven e in d ica las d iferencias de las fluctuaciones a largo y corto plazo para estos isótopos, que com para tam bién en conjunto con los de gran dem anda, suministrados por Oak Ridge.

D escribe muy brevem ente los métodos actuales de producción de todos los radioisótopos "especiales" y perlas marcadas actualm ente proporcionados por Brookhaven, incluyendo trabajos inéditos recientes, relativos a un "generador" de »A 1. la producción de 47Sc, e l increm ento de la activ idad específica de l **Mg hasta 40 m c /g y e l em pleo de 4.WH pata inducir reacciones (n , p a rtíc u la ) .

INTRODUCTION

U sefu l c h a r a c t e r i s t i c s of ra d io iso to p e s

T h e u s e fu l c h a r a c t e r i s t i c s of r a d io is o to p e s and th e a d v a n ta g e s w h ich m a y be ta k e n of th e s e c h a r a c t e r i s t i c s a r e w e ll known; n e v e r th e le s s i t m a y b e u se fu l to b eg in th is p a p e r by su m m a r iz in g th e m b r ie f ly .

(1) A lthough fo r so m e u s e s th e c h e m ic a l id e n ti ty of a ra d io is o to p e i s u n im p o r ta n t, and an y e le m e n t e m ittin g th e r e q u ir e d ty p e o f r a d ia t io n w ith the p ro p e r e n e rg y and h a lf - life would do, fo r a g re a t m any u se s th e c h e m ic a l id e n ti ty of th e ra d io is o to p e p la y s an im p o r ta n t r o le . C h e m ic a lly a r a d io a c tiv e iso to p e b e h a v e s e x a c t ly l ik e a s ta b le is o to p e of th e s a m e e le m e n t and , w ith few e x c e p tio n s , th e tw o a r e in s e p a ra b le and in d is tin g u ish a b le by o r d in a r y c h e m ic a l m e a n s . T h is c h a r a c t e r i s t i c fo rm s th e b a s i s on w h ich r a d io is o to p e s m a y be u s e d a s t r a c e r s .

T h e "e x c e p tio n s" to th e id e n tity of c h e m ic a l b eh av io u r a re m o re o s te n s ib le th a n r e a l . U n d e r s p e c ia l c o n d itio n s (u su a lly th o s e in w h ich c h e m ic a l ex ch an g e d o es n o t ta k e p la c e ) , a ra d io is o to p e m a y e x is t in a v a le n c e s ta te d if fe re n t f ro m th a t of th e s ta b le iso to p e s p r e s e n t o r th a t in w hich th e s ta b le iso to p e s would be ex p ected to l ie if th ey w ere p re s e n t. T h is m ay o c c u r e i th e r b e c a u s e of th e m o d e of fo rm a tio n of th e ra d io is o to p e [1] o r b e c a u s e o f th e r a d ia t io n a s s o c ia te d w ith i t s d e c a y . A s e c o n d " e x c e p tio n " m a y o c c u r in s y s te m s co n ta in in g ra d io iso to p e s of low m a s s n u m b e r u n d erg o in g r e a c t io n s in w h ich c h e m ic a l k in e t ic s a r e im p o r ta n t [2] . T h is a r i s e s b e c a u s e o f te n th e r a te of a r e a c tio n d epends p a r t ly on th e m a s s of a re a c tin g p a r t ic le , and in lo w -m a s s r a d io is o to p e s th e r e la t iv e d if fe re n c e in m a s s e s b e c o m e s a p p ré c ia b le (fo r e x a m p le , th e m a s s of H? i s v i r tu a l ly th r e e t im e s th a t o f H 1).

(2) A se c o n d u s e fu l c h a r a c t e r i s t i c o f r a d io is o to p e s i s th a t r a d ia t io n e m itte d by th e m e n a b le s d e te c tio n o f e v e n e x t r e m e ly m in u te t r a c e s o f th e

6 L. G. STANG, JR.

ra d io is o to p e , o f ten r e la t iv e ly e a s i ly , f ro m o u ts id e th e s y s te m c o n ta in in g th e ra d io is o to p e and w ithou t d is tu rb in g th is s y s te m .

(3) T h e ra d ia t io n m ay be u se d to e ffe c t c e r ta in b e n e f ic ia l d e s tru c t iv e c h a n g e s , fo r exam ple , the d e s tru c tio n of c a n c e r c e l l s , b a c te r ia , m ic ro b e s and v e rm in and in h ib itio n of th e g ro w th of s p ro u ts in s to r e d p o ta to e s [52] .

(4) T h e r a d ia t io n m a y e ffe c t c e r ta in c o n s tru c t iv e c h a n g e s , s u c h a s th o s e o c c u r r in g in th e p o ly m e r iz a tio n of m o n o m e rs and th e c r o s s - l in k in g of p o ly m e rs w hen a p p ro p r ia te s y s te m s con ta in ing th e m a r e exposed to r a d i a tio n [4, 5, 6].

(5) T h e r a d ia t io n m a y b e u se d d ir e c t ly to p ro d u c e ra d io g ra p h s [7] and au to ra d io g ra p h s o r to a c tu a te in d ic a tin g , r e c o rd in g and co n tro llin g d e v ic e s .

(6) F in a lly an in te r e s t in g u s e fu l c h a r a c t e r i s t i c of r a d io is o to p e s , of w hich advan tage can be ta k en o c c as io n a lly , is th e i r m ode of fo rm a tio n . F o r in s ta n c e , i t m a y a t t im e s be p r e f e r a b le to in tro d u c e a p a r t i c u la r e le m e n t, o r iso to p e of th a t e le m e n t, in to a s y s te m no t by adding th e iso to p e d ir e c t ly bu t by in tro d u c in g th e p a re n t m a te r ia l and a llow ing th e n a tu ra l ra d io a c tiv e d ec ay of th e p a re n t to fo rm th e d e s ire d d au g h te r in s i t u . F o r ex a m p le , th is p e r ta in s w hen th e d a u g h te r h a s su c h a s h o r t h a l f - l i f e th a t d i r e c t w o rk is im p r a c t ic a l . It is a ls o t r u e in so m e c a s e s w h e re th e o n ly p o s s ib le w ay of in c o rp o ra t in g a t r a c e of m a te r i a l in to a g iv e n l a t t ic e p o s it io n in a c r y s ta l i s to m a k e a c r y s t a l co n ta in in g th e p a r e n t and a llo w th e d a u g h te r to g ro w in f ro m d e c a y of th e p a r e n t [8].

A dvan tages of s h o r t h a lf - life

In th e an n o u n cem en t of th is m e e tin g , fo u r p o s s ib le ad v a n ta g es of u s in g s h o r t - l iv e d is o to p e s , r a th e r th a n lo n g - l iv e d o n e s , w e re e n u m e ra te d : (1) re d u c tio n in r a d ia t io n d o se in m e d ic a l a p p lic a tio n s ; (2) e lim in a tio n of th e ra d io a c tiv e co n ta m in a tio n of in d u s t r ia l p ro d u c ts d u r in g th e m a n u fa c tu re of w h ich r a d io is o to p e s w e re u se d a s p r o c e s s c o n tro ls ; (3) th e p o s s ib i l i ty of m a k in g r e p e a te d m e a s u r e m e n ts on th e s a m e s y s te m v ia r e p e a te d " d o s e s 11 of ra d io iso to p e w ithout having to apply c o r re c tio n s fo r re s id u a l ra d io a c tiv ity le f t f ro m p re v io u s m e a s u re m e n ts ; and (4) th e e l im in a tio n o r m in im iz a tio n of th e w a s te - d is p o s a l p ro b le m . In ad d itio n to th e s e a d v a n ta g e s th e r e a r e tw o f u r th e r r e a s o n s w hy th e o p e r a to r s of s m a l l r e s e a r c h r e a c t o r s , and p r o d u c e r s of is o to p e s in th e te c h n ic a l ly le s s - d e v e lo p e d c o u n t r ie s sh o u ld c o n c e rn th e m s e lv e s m o r e w ith s h o r t - l iv e d is o to p e s th a n lo n g - liv e d o n e s , n a m e ly eco n o m y and s u i ta b i l i ty of p ro d u c tio n .

It c a n be show n th a t a l a r g e r e a c to r , and l a r g e p ro c e s s in g f a c i l i t i e s , c a n p ro d u c e r a d io is o to p e s m o re e c o n o m ic a lly th a n i s p o s s ib le in a s m a l l r e a c to r hav ing s m a ll p r o c e s s in g fa c il i t ie s ; th a t i s , th e to ta l c o s t p e r m illi- c u r ie p ro d u c e d is l e s s in th e f i r s t c a s e th a n in th e se c o n d . T h is i s bound to b e t r u e i f o p e ra tin g c o s ts on ly a r e c o n s id e re d , and I s u s p e c t i t i s a ls o th e c a s e i f th e in i t ia l c a p i ta l in v e s tm e n t i s in c lu d e d , if th is i s so i t i s re a s o n a b le to a s su m e th a t lo n g e r- liv e d iso to p e s can be im p o rte d m o re ec o n o m ic a l ly f ro m c o u n tr ie s p o s s e s s in g l a r g e r e a c to r s and l a r g e p ro d u c tio n f a c i l i t i e s u n le s s , o f c o u r s e , th e r e i s a la rg e d is p a r i ty in la b o u r c o s ts , in t e r e s t c h a r g e s , e tc . b e tw e en th e im p o r tin g and e x p o rtin g c o u n t r ie s , o r u n le s s th e t r a n s p o r ta t io n c h a r g e s a r e h ig h enough to o u tw eig h th e f a c to r o f la rg e -v o lu m e eco n o m y .


H ow ever, w h a te v e r is th e c a s e w ith r e g a rd to lo n g -liv e d ra d io iso to p e s , i t i s q u ite c l e a r th a t , ex c e p t in v e r y s p e c ia l c a s e s (e. g . th o s e in w h ic h a " m ilk in g 11 s y s te m c o n ta in in g a p a r e n t iso to p e i s sh ip p e d , s e e b e lo w ), th e e x p e n se and o th e r p ro b le m s a s s o c ia te d w ith th e t r a n s p o r ta t io n of s h o r t liv e d r a d io is o to p e s f ro m one c o u n try to a n o th e r u s u a lly r e n d e r s th i s p r o c e d u re im p r a c t ic a l . F o r ex a m p le , a s th e r a t io of s h ip p in g - t im e /h a lf - l i f e i n c r e a s e s , in o r d e r to r e c e iv e a g iv e n am o u n t of m a te r i a l one m u s t s t a r t w ith a co n s id e ra b ly la r g e r am ount of the m a te r ia l a t th e sh ipp ing po in t. T h is r e q u ir e s e i th e r m o re sh ie ld ing th roughou t the e n t ire jo u rn ey , o r re -p a c k a g in g in t r a n s i t , e i th e r o f w hich is ex p en siv e . When p ro b le m s co n n ec ted w ith c u s to m s c le a ra n c e , t im e of sh ip m en t and t im e of u sa g e to c o r re s p o n d w ith av a ila b le a ir l in e sc h e d u le s , e tc . a re a lso taken in to c o n s id e ra tio n it is c le a r th a t s h o r t- l iv e d iso to p es a r e b e s t m ade lo c a lly .

A n o th e r f a c to r fa v o u r in g th e u s e o f s m a l l r e s e a r c h r e a c t o r s f o r th e p ro d u c tio n of s h o r t - l iv e d r a th e r th a n lo n g - liv e d r a d io is o to p e s i s th e p r o nounced e ffec t of h a lf - l if e on th e n e t r a te o f p ro d u c tio n . T h e s a tu ra t io n a c t iv i ty As, i s in d e p e n d e n t of th e h a l f - l i f e of th e p ro d u c t and i s g iv e n by

A s = Np0CTp,

w h ere Np is th e n u m b e r of a to m s of th e p a r t i c u la r ta rg e t iso to p e , ap is the a c tiv a tio n c r o s s - s e c t io n (cm 2 ) of th a t iso tope to p ro d u ce the p roduct in q u estio n , 0 i s th e flux (n cm'2 s_1 ) o f p a r t i c le s (n e u tro n s) g iv ing r i s e to th e r e a c tio n , and As i s th e a c tiv i ty (d is in te g ra t io n s p e r se c o n d ) p ro d u c e d by an in f in ite ly - lo n g ir ra d ia t io n . H ow ever, i f the i r r a d ia t io n is fo r a fin ite len g th of t im e , t , th e a c tiv ity , At , p ro d u c e d a t th e end of th e i r r a d ia t io n is g ivenby

A t = Np a p0 ( l - e‘°-693t/T4 ),'P

w h ere A t is in d is in te g ra tio n s p e r second and T j is the h a lf - life of th e p ro d u c t in th e s a m e u n its a s t . T h u s , a ll o th e r th in g s being eq u a l, th e s h o r te r th e h a l f - l i f e , th e l a r g e r th e am ount of a c tiv i ty p ro d u c e d in a g iven i r r a d i a t io n t im e . In s m a l l r e s e a r c h r e a c t o r s b o th th e s p a c e and th e t im e w h ich can be a llo tte d to th e i r ra d ia t io n of a g iven sa m p le a re lim ite d and a re th e re fo re a t a p re m iu m ; th u s su c h r e a c to r s , w hile p ro d u c in g only lim ite d am ounts o f lo n g - liv e d r a d io is o to p e s , w ill p ro d u c e u s e fu l and s a t i s f a c to r i ly l a r g e a m o u n ts o f s h o r t - l iv e d is o to p e s .

I t m ig h t be p o in ted out p a re n th e tic a lly th a t th is e ffec t of s h o r t h a lf - l if e on a c tiv i ty p ro d u c e d m u s t a ls o be ta k e n in to ac c o u n t in c o n s id e r in g th e n e c e s s a r y p u r ity of th e ta r g e ts to be i r r a d ia te d , fo r a t r a c e im p u r ity w hich g iv e s r i s e to an a c tiv i ty h av in g a c o n s id e ra b ly s h o r t e r h a l f - l i f e th a n th a t o f th e d e s i r e d p r im a r y p ro d u c t o ften p ro d u c e s s u f f ic ie n t a c t iv i ty to m a s k th e d e s i r e d p ro d u c t, a t l e a s t t e m p o r a r i ly i f n o t p e rm a n e n tly , r e q u ir in g e i th e r a p o s t - i r r a d ia t io n c h e m ic a l p ro c e s s in g s te p to re m o v e th e im p u r ity and in c re a s in g th e handling p ro b le m s , o r a t le a s t re q u ir in g a cooling p erio d f o r d e c a y of th e im p u r i ty . T h e e ffe c t of h a l f - l i f e on a c tiv i ty p ro d u c e d i s r e f e r r e d to l a t e r in c o n n e c tio n w ith th e u s e of in - p i le lo o p s to u t i l i z e u l t r a - s h o r t - l i v e d r a d io is o to p e s and th e u s e of s ta b le is o to p e s a s t r a c e r s .

8 L. G. STANG, JR.

P lan n in g ahead

T h e h a l f - l i f e o f a ra d io is o to p e i s on ly on e o f th e c h a r a c t e r i s t i c s o f r a d io is o to p e s w ith w h ich r e a c to r o p e r a to r s an d is o to p e p r o d u c e r s m u s t b e c o n c e rn e d . O th e r c h a r a c t e r i s t i c s in c lu d e th e ty p e o f e m itte d r a d ia t io n an d i t s e n e rg y . T h is i s a n e c e s s a r y c o n c e rn in a sm u c h a s a p ro d u c e r m u s t t r y to a n t ic ip a te th e n e e d s o f th e u s e r b e c a u s e o f te n s ix to tw e n ty -fo u r m o n th s o r ev e n io n g e r a r e r e q u i r e d to d ev e lo p a p r o c e s s fo r p ro d u c in g a p a r t i c u la r “ s p e c ia l" ra d io is o to p e . A lthough i t sh o u ld be th e r e s p o n s ib i l i ty o f th e u s e r to f o r e c a s t h is n e e d s a n d /o r to g iv e h is b a s ic r e q u i r e m e n ts , to g e th e r w ith r e a s o n s f o r h is s p e c if ic r e q u e s t s , s o th a t th e p r o d u c e r ca n s u g g e s t p o s s ib le a l te r n a t iv e s , th e p r o d u c e r i s o f te n n o t a b le to w a it f o r s u c h a f o r e c a s t .

T o i l l u s t r a t e th e c o n s id e r a t io n s , an is o to p e w h ich e m its o n ly a b e ta p a r t i c le m ay b e d e s ir e d [9] , p a r t i c u la r ly fo r c e r ta in m e d ic a l a p p lic a tio n s , in o r d e r to e l im in a te g am m a i r r a d ia t io n of th e w hole body a n d /o r to p ro v id e m o r e in te n s e ly - lo c a l iz e d i r r a d ia t io n of t i s s u e . A lte rn a tiv e ly a p u r e a lp h a- e m lt te r m a y b e n eed ed to p ro v id e s t i l l m o re in te n s e ly - lo c a liz e d i r r a d ia t io n [10]. A n is o to p e w h ich e m its a n X - r a y on ly [11] o r a r e la t iv e ly s o f t ( e .g . ~ 1 0 0 keV ) g a m m a - ra y m a y b e n e e d e d in o r d e r to r e d u c e so m e w h a t th e w h o le-b o d y i r r a d ia t io n o v e r w hat w ould be r e c e iv e d u s in g a h a r d e r g am m a b u t a t th e s a m e t im e p ro v id e a so m e w h a t l a r g e r and m o re u n ifo rm s p h e re o f i r r a d ia t io n th a n m ig h t be a t ta in e d w ith a p u r e b e t a - o r a p u r e a lp h a - e m i t t e r , d ep e n d in g on th e m o d e of a p p l ic a tio n . M o d e ra te ly s o f t g a m m a s a l s o p ro v id e g r e a t e r c o n t r a s t in r a d io g ra p h ic f i lm s th a n h a r d e r g a m m a s . O n th e o th e r h an d , i f th e is o to p e i s to b e u se d a s a t r a c e r w h ich i s to be d e te c te d by co u n tin g eq u ip m en t e x te rn a l to th e s y s te m in w h ich th e iso to p e i s in tro d u c e d , o r i f i t i s to p ro v id e a g r e a t e r s p h e r e o f i r r a d ia t io n , one w h ich e m its a h a r d b e ta o r a h a r d g a m m a w ill b e d e s i r e d .

M any p eop le in th e l a s t s e v e ra l y e a r s have b ee n u sin g p o s itro n e m itte r s [12] to p e r m i t " p in -p o in t11 lo c a liz a tio n o f su c h a t r a c e r by m e a n s of c o in c id en c e coun ting of th e p a i r of g am m as com ing off in opposite d ire c tio n s when th e p o s i t ro n i s a n n ih ila te d ; o b v io u sly , fo r su c h p u rp o s e s th e m o s t su ita b le is o to p e s w ou ld b e th o s e in w h ich a h ig h p e rc e n ta g e of th e d e c a y o c c u r s by p o s i t ro n e m is s io n r a th e r th a n by e le c tro n c a p tu re o r n eg a tro n e m is s io n and th o s e in w h ich p r im a r y g a m m a e m is s io n (in c o n t r a s t to th e a n n ih ila tio n g a m m a s ) is a t a m in im u m . D epend ing on th e u s e s c o n te m p la te d , is o to p e s m a y b e d e s i r e d w hich have s im p le d ec ay sc h e m e s [13], o r p a r t i c u la r k inds o f d e c a y s c h e m e s , o r p e a k s a t c e r ta in e n e r g ie s , in o r d e r to p e r m i t e a s ie r and m o re ra p id d e tec tio n of th e iso to p e in ques tion (e. g. v ia gam m a s p e c tro m e try ) in the p re s e n c e of o th e r iso to p e s .

A s w ill b e n o te d below in d is c u s s in g m ilk in g s y s te m s , th e p o s s ib i l i ty o f p r e p a r in g a g iv e n is o to p e by is o la t io n and s h ip m e n t o f i t s p a r e n t m u s t n o t b e o v e r lo o k e d . F in a l ly , in s e le c t in g th e m o s t s u i ta b le h a l f - l i f e , ty p e o f r a d ia t io n , and e n e rg y o f r a d ia t io n , one m u s t n o t o v e r lo o k th e c h e m ic a l and s o m e tim e s p h y s io lo g ic a l p r o p e r t i e s o f th e e le m e n ts to b e p ro d u c e d .

A d v a n ta g e s o f a r e a c t o r o v e r an a c c e le r a to r

M any is o to p e s , u s u a lly n e u t ro n - d e f ic ie n t o n e s , c a n b e m a d e o n ly in a p a r t i c l e a c c e le r a to r su c h a s a c y c lo tro n , s y n c h ro tr o n , V an d e G ra a f f ,


e t c . , e i th e r by c o n v e n tio n a l r e a c t io n s , su c h a s (a , n ), (d ,n ) , e t c . , o r by s p a lla t io n . O th e r s , u s u a lly th e n e u tro n ,- r ic h o n e s , c a n b e m a d e o n ly in a n u c le a r r e a c to r , e i th e r by s in g le n e u tro n c a p tu re ( e .g . N i65) , 'm u lt ip le n eu t r o n c a p tu r e ( e .g . ~Cf252), o r a s a f is s io n p ro d u c t ( e .g . 1135). S ti l l o th e r s ca n be m ade by e i th e r an a c c e le ra to r o r a r e a c to r . W here th e re i s a ch o ice i t w ill u s u a lly be found th a t th e .r e a c to r o f fe rs m any ad v a n ta g es n o t o ffe re d by an a c c e le ra to r .

M ost r e a c t o r s a r e c a p a b le of i r r a d ia t in g , a t m a x im u m f lu x , l a r g e r t a r g e ts th a n ca n be b o m b a rd e d in an a c c e le ra to r . W hile i t is t r u e th a t m o s t a c c e le r a to r s h av e su f f ic ie n t s p a c e a ro u n d th e b e a m p o r t to a c c o m m o d a te a r a th e r l a r g e ta r g e t , and w hile i t i s a ls o t r u e th a t often th e b ea m is in te n t io n a lly s p r e a d out o v e r a r e la t iv e ly l a r g e a r e a in o r d e r to f a c i l i t a te th e p ro b le m of co o lin g th e t a r g e t , n e v e r th e le s s th is p ro c e d u re a lm o s t a lw a y s r e s u l t s in a d e c r e a s e in f lu x o f b o m b a rd in g p a r t i c l e s , th e to ta l n u m b e r p e r se c o n d r e m a in in g a p p ro x im a te ly c o n s ta n t . In h e re n t d if f e r e n c e s b e tw e e n n e u tro n s and c h a rg e d p a r t i c le s r e s u l t in m uch s h o r te r ra n g e s fo r th e l a t t e r g roup; th e e ffec t of th is is to r e s t r i c t th e u se fu l th ic k n e s s of an a c c e le ra to r t a r g e t w h ile a llo w in g r e la t iv e ly th ic k r e a c to r t a r g e t s to b e u s e d . On th e o th e r hand, in a r e a c to r th e p re se n c e of c e r ta in h igh c r o s s - s e c t io n e lem en ts in a ta rg e t l im its the th ic k n e s s of ta rg e t w hich can be accom m odated ; fu r th e r m o r e , ev e n w ith ta i 'g e ts o f on ly m o d e ra te ly h ig h c r o s s - s e c t i o n , a s u f f i c ie n tly la rg e t a r g e t w ill d e p r e s s th e flux in th e v ic in ity of th e ta r g e t . Howe v e r , th e s e e f f e c ts a r e u s u a l ly n o t n e a r ly s o p ro n o u n c e d in a r e a c t o r a s in an a c c e le r a to r .

F o r a n u m b e r of re a s o n s no ted below , th e leng th of th e i r ra d ia t io n t im e a v a ila b le , w h e th e r th e to ta l in te g r a te d le n g th , o r th e le n g th o f an y g iv e n co n tin u o u s i r r a d ia t io n , i s f a r g r e a t e r in a r e a c to r th a n in an a c c e le r a to r . T h e c o s ts p e r sa m p le i r ra d ia te d a r e u su a lly c o n s id e rab ly lo w er in a r e a c to r th a n in an a c c e le r a to r , and i f th e s e f ig u re s w e re n o r m a l iz e d to th e s a m e f lu x (s e e b e low ) o f b o m b a rd in g p a r t i c l e s , th e d is p a r i ty in c o s t s w ou ld b e s t i l l g r e a te r . [T he l a t t e r h a lf of th is s ta te m e n t r e f e r s to a c o m p a r is o n b e tw e e n (n ,7 ) r e a c t io n s p ro d u c e d in an a c c e le r a to r and (n ,7 ) r e a c t io n s p r o d u ced in a r e a c to r ; i f one c o m p a re s (n, y) r e a c t io n s p ro d u c e d in a r e a c to r w ith th e equ ivalen t a c c e le ra to r-p ro d u c e d re a c tio n s lead ing to th e sam e p ro d u c t , th e d i s p a r i ty in f lu x e s o f b o m b a rd in g p a r t i c l e s , and h e n c e in c o s ts p e r m i l l ic u r ie p ro d u c e d , b e c o m e s so m e w h a t l e s s and o c c a s io n a lly m ig h t co n ceiv ab ly even be r e v e r s e d , depending on n eu tro n c a p tu re c r o s s - s e c t io n s in v o lv e d , th e h e ig h t and sh a p e of th e c h a rg e d p a r t i c l e e x c i ta t io n fu n c tio n in v o lv e d , and th e p a r t i c l e e n e r g ie s a v a i la b le .]

A lthough a c c e le r a to r s o c c a s io n a lly i r r a d ia te tw o, o r even th r e e s a m p le s s im u lta n eo u sly , the n u m b er of sa m p le s w hich can be i r ra d ia te d s im u ltan eo u sly , m even th e s m a lle s t r e a c to r s is u su a lly m any m o re . A l e s s ta n g ib le advantage w hich canno t be o v erlo o k ed is the fa c t th a t m o s t r e a c to r s a r e in h e re n tly m uch m o re s ta b le and r e l ia b le in th e ir o p e ra tin g c h a r a c te r is t ic s th an a c c e le ra to r s , w hich a r e often p lagued by p ro b lem s of m ain ta in ing su ffic ien t vacuum , locating and fo c u s in g th e b e a m , m a in ta in in g 'a t t im e s d e l ic a te co o lin g s y s t e m s , e tc .

F lu x e s of lo iâ n c m ^ s ’ 1 a r e now e a s i ly a c h ie v e d in m a n y r e a c t o r s , and f lu x es of 1012 have b ec o m e qu ite com m on ev e n in s m a ll r e a c to r s [14]. A lth o u g h in th e c a s e of a c c e le r a to r s i t i s n o t to o d if f ic u lt to o b ta in f lu x e s

10 L. G. STANG, JR.

of p ro to n s , d e u te ro n s , o r alpha p a r t ic le s of 1014 p a r t ic le s c m '2 s '1 C1), fluxes o f a c c e le ra to r -p ro d u c e d n e u tro n s , w h e th e r f a s t o r slow , a r e le s s them 109 nc m - 2 s - i (2)(3).

In h e ren t d if fe re n c e s betw een a r e a c to r and an a c c e le ra to r u su a lly m ake e a s i e r th e h an d lin g of i r r a d ia te d t a r g e t s f ro m th e r e a c to r and th is i s a c co m p an ied by lo w e r e x p o su re to r a d ia tio n of o p e ra tin g p e rs o n n e l. T h e r e a c to r a lso m o re re a d ily acco m m o d ates s p e c ia l ta r g e ts , su ch a s c irc u la tin g lo o p s, and is m o re adap tab le to re p e tit iv e p lacem en t of the sa m e , o r s im ila r ta rg e ts .

F in a lly , w hen L iB (e ith e r a s n a tu ra l lith iu m o r lith iu m en ric h e d in th is is o to p e ) i s in c o rp o ra te d w ith a s e c o n d a ry t a r g e t and th e w hole i r r a d ia te d in a r e a c to r , th e r e a c to r s e rv e s as a s a t is f a c to r y s o u rc e of t r i to n s , a lb e it of m ax im um e n e rg y 2.7 M eV. C o n s id e rin g th e a lm o s t u n iv e rs a l r e lu c ta n c e of a c c e le ra to r o p e ra to rs to in tro d u c e t r i t iu m in to th e i r m a c h in e s , th is f e a tu r e c a n b e c o m e an im p o r ta n t a d v a n ta g e fo r s p e c ia l p u r p o s e s and i s d i s c u s s e d f u r th e r below .

PRO D U C TIO N TECH N IQ U ES

S tra ig h tfo rw a rd {n,y) r e a c t io n s

M ost r a d io is o to p e s a r e p ro d u c e d e i th e r by th e (n ,? ) r e a c t io n , w ith no p o s t- i r ra d ia t io n p ro c e s s in g of the ta rg e t , o r as a f is s io n p ro d u ct w ith r a th e r s t r a ig h tf o rw a r d , a lth o u g h s o m e tim e s d if f ic u lt and c o m p lic a te d , p o s t i r r a d ia t io n c h e m ic a l p r o c e s s in g and s e p a r a t io n . I w ill n o t d is c u s s th e s e p r o c e s s e s bu t w ill co n fin e m y r e m a r k s to th e u n u su a l, o r l e s s f re q u e n tly u s e d , te c h n iq u e s .

(n ,p ) r e a c t io n s

T h e (n ,p ) r e a c t io n is a u se fu l one w h ere i t c a n be ap p lied , a s i t y ie ld s a p ro d u c t w h ich i s a d if fe re n t e le m e n t f ro m th a t o f th e t a r g e t and w h ich , th e r e f o r e , ca n be s e p a r a te d , a t l e a s t th e o re t ic a l ly , in th e ' ‘c a r r i e r - f r e e " s ta te . [T h is i s in c o n t r a s t to th e (n ,y) r e a c t io n in w h ich th e p ro d u c t is th e s a m e e le m e n t a s th a t of th e t a r g e t and in w h ich th e s p e c if ic a c t iv i t ie s ob ta in a b le a r e o ften qu ite l im ite d , depending upon th e c r o s s - s e c t io n involved , th e ab u n d an ce of th e t a r g e t is o to p e , and th e f lu x a v a ila b le , u n le s s s p e c ia l r e c o i l te c h n iq u e s , d is c u s s e d below , a r e em p lo y ed .] E ven though m o re th an

^ A ccelerator beam output is always given in terms of p a rtic le current, rather than p a rtic le f lu x . However, ex ternal currents o f SO jiA are a tta ined by many accelerators [SO]. Fifty m icroam peres correspond to З х 10м singly-charged ions per second. A ta rge t area o f 1 cm* is not unusual.

For exam ple, although the Picker-Dresser 2920 Neutron G enerator generates 108 n /s , th e usable flux a t the surface o f the tube is only 5 x 10« n c m " 1 s_1 (Picker X -ray C orp ., White Plains, N .Y ., brochure dated Septem ber, 1961),

^ The Texas Nuclear Corporation Neutron G enerator, w hile producing 4 x 1010 n r 1 , provides a usab le therm al neutron flux o f only 5 x 10» n c m - » s ' > and presumably a usable fast flux not much h igher. See also the final paragraph in th e present paper.


h a lf o f th e p o s s ib le (n, p ) r e a c t io n s fo r w h ich d a ta a r e a v a ila b le [15] h av e a p o s it iv e Q , n e v e r th e le s s , w ith th r e e e x c e p tio n s , u s e fu l r e a c t io n s of th is ty p e r e q u i r e h ig h -e n e rg y n e u tro n s in o r d e r to p ro v id e su f f ic ie n t e n e rg y to e je c t th e outgoing p ro to n o v e r th e p o te n tia l b a r r i e r of th e com pound n u c leu s . S ince th e p o te n tia l b a r r i e r in c re a s e s as th e a tom ic n u m b e r, Z , of th e ta rg e t i n c r e a s e s , th is r e a c t io n is n e v e r lik e ly to be of v e r y p r a c t ic a l im p o r ta n c e in th e re g io n of h ig h -Z t a r g e ts .

A s m ig h t be ex p ec ted , th e th r e e ex cep tio n s o c c u r w ith re la t iv e ly lo w -Z t a r g e t s and , b e in g th e m a in s o u r c e s of c o m m e r c ia l ly -a v a i la b le C14 , P 3Z, and S3®, a r e v e r y im p o r ta n t . H o w ev er, fo r t a r g e t s o f lo w - to -m e d iu m Z , th e (n ,p ) r e a c t io n m a y be e x p e c te d to a s s u m e g r e a t e r im p o r ta n c e in th e fu tu re , a s r e a c to r s a r e b u ilt p ro v id in g h ig h e r fluxes of 5 -15 MeV n e u tro n s . Iso to p es lik e ly to be m ade by th is re a c tio n w ill inc lude P 33, C136 (for sp e c ia l p u rp o s e s ) , Mn54, and C o58, fo r th e p ro d u c tio n of e a c h of w h ich th e c r o s s - s e c tio n in a f i s s io n -n e u tro n sp e c tru m is e s tim a te d to be in e x c e s s of 50 m b [16] .

(n ,a ) re a c t io n s

Q u a li ta t iv e ! / th e s a m e ty p e o f s ta te m e n ts m a y be m a d e about th e (n ,a ) r e a c t io n s . A t th e p r e s e n t t im e th e only one of p r a c t ic a l im p o r ta n c e fo r i s o to p e p ro d u c tio n i s th e L i 6 ( n ,a ) H 3 r e a c t io n w h ich i s a s o u rc e o f t r i t i u m , of H es ( fro m th e d e c a y of t r i t i u m ) , and of r e c o i l in g t r i to n s w ith w h ich to e ffec t se c o n d a ry re a c t io n s . H ow ever, b ec au se of th e i r low e s tim a te d c r o s s - s e c tio n s [16] , o th e r (n,a) r e a c tio n s a r e not l ik e ly to be of g r e a t im p o rta n c e in th e fu tu re u n le s s v e ry h igh flu x es of h ig h -e n e rg y n e u tro n s beco m e a v a ila b le , in w h ich c a s e one m ig h t c o n s id e r p ro d u c in g c a r r i e r - f r e e N a24 f ro m A l27 fo r s p e c ia l p u r p o s e s .

O th e r n e u tro n - in d u c e d r e a c t io n s

E x c e p t in v e r y s p e c ia l and u n u su a l c a s e s , (n, 2n) r e a c t io n s as a c l a s s m a y be d is m is s e d a s being of l i t t l e p r a c t ic a l im p o r ta n c e . T h is a r i s e s b e c a u se (1) a ll su c h r e a c tio n s a r e én d o e rg ic and r e q u ir e fa s t n e u tro n s , w hich a r e l e s s n u m e ro u s th an th e rm a l n e u tro n s in m o s t r e a c to r s ; (2) c r o s s - s e c tio n s a r e a lm o s t u n iv e rs a lly v e ry low [16] ; and (3) th e r e a c tio n p ro d u c t is an iso to p e of th e s a m e e le m e n t a s th e ta r g e t , im p ly in g th a t th e sp e c if ic a c tiv i ty of th e p ro d u c t w ill a lw a y s be low and th a t a c a r r i e r - f r e e p ro d u c t i s im p o s s ib le . B e c a u se of th e e n e rg y r e q u ir e m e n ts , o th e r r e a c t io n s su c h a s (n ,p n ), (n, 2р)^ (n, 3n), e t c . , w ill a lso n e v e r be of g e n e ra l p r a c t ic a l im p o r ta n c e , a lth o u g h th e y m a y b e of u s e in s p e c ia l c a s e s in w h ich no o th e r r e a c t io n w ould y ie ld th e d e s i r e d p ro d u c t.

S o u rc e s of f a s t n e u tro n s

If p r im a r y n e u tro n - in d u c e d r e a c t io n s o th e r th a n (n,y), and a c e r ta in few ex c e p tio n a l (n, p ) and (n,a) r e a c t io n s Eire to be e f fe c te d , f a s t n e u tro n s w ill be r e q u ire d . U sefu lly , h igh flu x es of su ffic ie n tly fa s t n eu tro n s fo r such p u rp o s e s c a n b e p ro d u c e d in a r e a c t o r . T h e c o n v e n tio n a l m e th o d [17] i s

12 L. G. STANG, JR.

to s u r ro u n d th e ta r g e t w ith a f is s io n a b le m a te r ia l su c h a s U 235 t w hich a b s o rb s th e rm a l n e u tro n s and e m its f is s io n n e u tro n s w ith an en e rg y sp e c tru m ex tending w ell above lO M eV, the nu m b er d im in ish in g ra p id ly w ith in c re a s in g e n e rg y . T h is m a y b e a c c o m p lis h e d by c o n v e r tin g a r e g u la r fu e l e le m e n t in to a s p e c ia l one by d r i l l in g a h o le in i t in w h ich th e s a m p le m a y h e in s e r te d , o r by fa b r ic a tin g a s p e c ia l u ra n iu m c o n ta in e r in w hich th e s a m p le i s p la c e d d u r in g i r r a d ia t io n . It m a y a lso be a c c o m p lish e d w ith c e r ta in a d v a n ta g e s b y u s in g l i th iu m - 6 d e u te r id e , L iBD , in s te a d o f U235 to s u r ro u n d th e s a m p le [18] . T h e L i6 В te c h n iq u e , w h ich i s d e s c r ib e d in m o r e d e ta i l below , in v o lv es tw o s u c c e s s iv e r e a c tio n s : L i 6 (n, t)H e4 and H 2 ( t,n )H e 4 . A lth o u g h th e s e te c h n iq u e s , w hen u s e d in a r e a c to r h av in g a th e r m a l f lu x of abou t 1 0 13 n c m -2 S '1 , p ro d u c e f a s t n e u tro n s h av ing f lu x es no t m u ch h ig h e r th a n th o s e o b ta in a b le in a c c e le r a to r s , so m e of th e a d v a n ta g es of r e a c to r s o v e r a c c e le r a to r s no ted above m ake th e r e a c to r an a t t r a c t iv e to o l fo r i s o to p e p ro d u c tio n re q u ir in g th e u s e of f a s t n e u tro n s .

S eco n d a ry re a c t io n s induced by t r i to n s

T he L i 6 (n, a-)H3 (or L i6 (n,t)H e4 ) re a c tio n r e f e r r e d to above h as a c ro s s - s e c t io n of 950 b fo r th e rm a l n e u tro n s and p ro d u c e s 2 .7 3 -M eV t r i t o n s and2.05-M eV a lpha p a r t ic le s . Such an a lpha p a r t ic le is not su ffic ien tly e n e rg e tic to p e n e tr a te th e C oulom b b a r r i e r of o th e r n u c le i, and hence canno t be u se d to e ffec t o th e r (a, p a r t ic le ) re a c t io n s № . (The u s e of f a s t r a th e r th a n th e r m a l n eu tro n s would y ie ld a lphas of h ig h e r en e rg y but red u ced flux, the la t te r b e in g due to th e u su a lly s m a ll r a t io of f a s t / th e r m a l n e u tro n s and to th e d e c r e a s e in c ro s s - s e c t io n fo r the re a c tio n c ited as n eu tro n energy in c re a s e s . )

H o w ev er, th e t r i to n is s u f f ic ie n tly e n e r g e t ic to e ffe c t ( t ,p ) and (t, n) r e a c t io n s in c e r ta in n u c le i. A d van tage m a y be ta k e n of th is by i r r a d ia t in g s e le c te d com pounds o r a llo y s of n a tu ra l lith iu m o r e n ric h e d l i th iu m - 6 . F o r in s ta n c e , w hen L Í 2C O 3 i s i r r a d ia te d , th e r e c o i l in g t r i to n p ro d u c e d f ro m th e L i6 c o l l id e s w ith an 0 16 a to m in th e c a rb o n a te to p ro d u c e O i6 ( t , n ) F i 8

[1 9 ,2 0 ,2 1 ] . S im ila r ly , w hen a l i th iu m -m a g n e s iu m a llo y i s i r r a d ia te d , th e re c o f l in g t r i to n s e ffe c t th e M g 26(t,p)M g28 r e a c t io n [21, 22]. B o th of th e s e ex am p les fo rm th e b a se s of p ro d u ctio n m ethods c u r re n tly u sed at B rookhaven N a tio n a l L a b o r a to ry and a r e d e s c r ib e d in m o r é d e ta i l b e lo w . RU D EN KO and SEVASTIANOV [23] have r e p o r te d finding th e L i6 (t, 2n)Be7 re a c tio n when L i 6 i s i r r a d ia te d in a r e a c to r l5) . B ISHO P [3] r e c e n t ly found B e 7 in an

(4) iC oncern ing theca tego ricalsta tem en t th a t the alpha from this reaction is not sufficiently energeticto effect other reactions, an apparent exception to this Is found In the work of ROY and HAWTON [53] whow ere able to effect the Blr'(ct, n) N ‘ 3 reaction with alphas from the B ^ n , a ) Li' reaction . Seven percent of thealphas from the la tte r reaction have an energy of 1 .8 MeV w hile 93% have an energy of only 1 .5 MeV,when the neutrons producing them are therm al [15,40] . However, the ca lcu la ted Coulomb barrier for theBl0(ct>n) reaction is 2.5 to 3 .2 MeV, depending on what value is used for th e radius of the alpha p artic le , andwhen conservation o f m om entum is taken in to consideration the m inim um alpha energy required for goingover th e Coulom b barrier would be 3.5 to 4 .5 M eV. Thus, i t would appear that this reaction is occurring byvirtue o f considerable tunnelling through th e barrier, which would be expected to occur to much less extentw ith heav ier target atom s, which have correspondingly even higher barriers.

^ ROY and HAWTON [53] c la im th a t BeT is formed not from U fi( t , 2n) Be7 reaction but rather from th e Li7 (p, n) reaction w ith protons com ing from the U6 (n, p) reaction . BISHOP’S work is prelim inary; he sim ply iden tified Be7 w ithout d ifferentiating the particu lar reaction m echanism .

A REVIEW OF THE PRODUCTION OF "SPECIAL” RADIOISOTOPES 13

a llo y of n a tu ra l m a g n esiu m and n a tu ra l lith iu m i r r a d ia te d fo r sev en w eeks in th e B ro o k h a v e n G ra p h ite R e s e a r c h R e a c to r ; th i s i s p r e s u m a b ly du e to th is sa m e re a c tio n . P a re n th e tic a lly , i t m ay be w o rth noting th a t th e O16 ( t,n ) F 18 r e a c t io n c r o s s - s e c t i o n i s h ig h enough to a llo w th i s r e a c t io n to fo rm th e b a s is of an a n a ly tica l m ethod fo r d e te rm in in g t r a c e s of oxygen in lith iu m .

T h e (t, n) r e a c t io n s have th e advan tage of p ro d u c in g iso to p e s w hich a re c a r r i e r - f r e e and w h ich m a y b e on th e n e u t ro n - d e f ic ie n t s id e of s ta b i l i ty , a re g io n not e a s i ly a tta in ed w ith a r e a c to r excep t by th is r e a c tio n . T he ( t,p ) r e a c t io n s h av e th e ad v an tag e of add ing tw o n e u tro n s a t one t im e , av o id in g th e d if f ic u l t ie s e n c o u n te re d in s u c c e s s iv e n e u tro n c a p tu r e , p a r t i c u l a r l y w hen th e in te r m e d ia te is s h o r t - l iv e d o r h a s a lo w c r o s s - s e c t i o n . F o r e x a m p le 2 1 -h M g28 i s p ro d u c e d d i r e c t ly f ro m s ta b le M g26 w ith o u t h av in g to go th ro u g h th e 9 .5 -m in M g27 in te r m e d ia te .

P r e p a r a t i o n s a r e b e in g m a d e a t BN L fo r e x p e r im e n ts w h ich w ill u s e re a c to r - in d u c e d ( t ,p ) r e a c t io n s in a t te m p ts to d is c o v e r new is o to p e s , su c h a s Ca50. (O th e rs h av e now d is c o v e re d th is is o to p e and r e p o r t a h a l f - l i f e o f ab o u t 12 m in . )

S e c o n d a ry r e a c t io n s in d u c ed by p ro to n s and d e u te ro n s

O p e ra to rs of r e a c to r s w hich u se w a te r (w hether lig h t, heavy , o r a m ix tu r e ) a s a m o d e ra to r sh o u ld n o t o v e r lo o k th e p o s s ib i l i ty of b e in g a b le to e f fe c t r e a c t io n s su c h a s (p, n ), (d, n ), e t c . , by u t i l iz in g th e "k n o c k e d -o n " o r e x c ite d p ro to n s and d e u te ro n s r e s u l t in g f ro m c o l l is io n s b e tw een f is s io n n e u tro n s and th e h y d ro g en o r d e u te r iu m in th e w a te r [24] W . F o r e x a m p le , th e fo rm a tio n of 2 0 -m in c a r b o n - 11 m ig h t be e ffec ted by th e B 11 (p, n )C 1:1 r e a c tio n , o r 5 3 -d b e r y l l iu m - 7 m ig h t b e m a d e by th e L i7 ( p .n ) B e ’ r e a c t io n . R e a c tio n s su c h a s C i2 (d, n)№ 3 and 0 17(d, n )F i8 o r O i8(d, 2n)Fi8 m ay r e s u l t fro m m a te r ia ls a s so c ia te d w ith the r e a c to r , p ro d u c in g u se fu l p ro d u c ts . The su b m e rs io n of sa m p le s of neon m ay r e s u l t in the fo rm a tio n of u se fu l am ounts o f c a r r i e r - f r e e N a 22, o r th e i r r a d ia t io n (w h e th e r d i r e c t o r p a r a s i t i c (se e below )) o f m a g n e s iu m m a y r e s u l t in u s e fu l am o u n ts o f c a r r i e r - f r e e A 1 2 6 .

A n o th e r te c h n iq u e w h ich m a y b e u s e fu l in s p e c ia l c a s e s , p a r t i c u la r ly in fu tu re r e a c to r s , i s th e p o s s ib ili ty of effec tin g re a c tio n s su ch as (p ,n ) and (p, 2n), u s in g p ro to n s f ro m th e H e3 (n, p )H 3 r e a c t io n . T h is r e a c t io n h a s a c r o s s - s e c t io n of 5400 b fo r th e rm a l n e u tro n s , a n d 'i t ca n be c a lc u la te d th a t th e p ro to n flux (in e i th e r liq u id o r g aseo u s H e 3 ) w ould be 40% of th e th e rm a l n e u tro n flux . T h u s th e r e a c to r - in d u c e d p ro to n flux w ould b e c o m p a ra b le to th a t p ro d u ced in m o st a c c e le ra to r s , and in add ition th e advan tages of r e a c to r o p e ra tio n o v e r a c c e le r a to r o p e ra tio n w ould b e r e ta in e d (s e e e a r l i e r p a r t o f th is p a p e r ) . H o w ev er, s in c e th e Q o f th is r e a c t io n i s on ly +0.76 M eV ,~ th e r e s u l t in g p ro to n s w ould have an e n e rg y of on ly 0.57 M eV , w hich is too low fo r in d u c in g o th e r r e a c t io n s . F o r e x a m p le , i t w ould b e e x p e c te d th a t the L i7 (p ,n )B e7 re a c tio n could-be effec ted m o re re a d ily than any of the o ther

^ Subsequent to the w riting of this paper a publication prior to reference [24] in the bibliography has been found concerning the u tiliza tion o f recoil protons [54] . Another ̂ reference has been found in which protons and deuterons from the ta rg e t itse lf have been used to effec t secondary reactions w ithin the sam e ta rge t [55] .

14 L. G. STANG, JR.

v a r io u s p o s s ib le p ro to n -in d u c e d r e a c t io n s , and y e t th is r e a c t io n w ould r e q u ire 1 .64-M eV p ro to n s . It can be c a lc u la te d th a t 1.43-M eV n e u tro n s would bè needed to p ro d u ce 1.64-M eV p ro to n s (and, in c id en ta lly , 0 .5 5 -MeV tr ito n s! In a sm u c h a s th e c r o s s - s e c t i o n fo r th e H e3 (n ,p )H 3 r e a c t io n fo r 1 .4 3 -M eV n e u tro n s i s on ly 0 .74 b [29] , in s te a d of 5400 b , i t c a n b e show n th a t th e flux of 1 .64-M eV p ro to n s would be only 0.014% of th e flux of 1 .43-M eV n eu t r o n s w h ich , in tu r n , i s c o n s id e ra b ly l e s s th a n th e th e r m a l f lu x in m o s t r e a c to r s (see fin a l se c tio n of th is p a p e r) . H ow ever when th e new H ig h -F lu x B e a m R e s e a r c h R e a c to r [26] p r e s e n t ly u n d e r c o n s tru c t io n a t B ro o k h a v e n N a tio n a l L a b o r a to ry (BN L) i s c o m p le te d , th is te c h n iq u e w ill b e one of s e v e r a l to b e in v e s tig a te d .

R e c o il te c h n iq u e s

(n ,y) r e a c t io n s , a s w e ll a s ( t ,p ) and (n, 2n) r e a c t io n s , (and of c o u r s e (d ,p ) and [y, n) r e a c tio n s in an a c c e le ra to r ) y ie ld p ro d u c ts w hich a r e iso topic w ith th e ta r g e t n u c leu s . As no ted above, su ch p ro d u c ts can n e v e r be c a r r i e r - f r e e , and in m a n y c a s e s th e sp e c if ic a c tiv ity o b ta in ab le by s t r a ig h tfo rw a rd m e a n s i s q u ite low . F o r m o s t c a s e s in w hich one of th e se re a c tio n s (u sually th e (n, y) re a c tio n ) is th e only p r a c t ic a l m ethod of p ro d u cin g a g iven iso to p e , b u t in w h ich a h ig h e r s p e c if ic a c tiv i ty i s r e q u i r e d , s p e c ia l t r i c k s h a v e to b e u se d .

AEBERSOLE) and R U P P (th ese P ro c e e d in g s ) m en tio n th e u se of s e p a ra te d is o to p e s a s t a r g e t s a s a m e a n s fo r in c r e a s in g th e s p e c if ic a c t iv i ty o f th e p ro d u c t. H o w ev er in c a s e s w h e re th e r e i s a n a tu ra lly , h ig h a b u n d a n ce of th e r e q u i r e d t a r g e t is o to p e , is o to p ic s e p a r a t io n d o e s n o t o f fe r s u f f ic ie n t im p ro v e m e n t to b e p r a c t ic a l , and in m a n y c a s e s ev en w hen th e t a r g e t h a s h ig h ab u n d an ce of th e r e q u ir e d iso to p e , e i th e r a low c r o s s - s e c t i o n o r low flu x a v a ila b le m a y p re v e n t th e a t ta in m e n t o f s u f f ic ie n tly h ig h s p e c if ic a c t iv i ty .

In su c h c a s e s r e c o i l tech n iq u es a re often u se fu l. In th e c la s s ic exam ple , th e S z i la r d - C h a lm e r s r e a c t io n [27], th e t a r g e t is c h o s e n so th a t w hen th e a to m s t r u c k by th e n e u tro n e m its a " c a p tu re " g am m a r a y and r e c o i ls aw ay f ro m th e ta rg e t m o le cu le , recom bin 'a tion is un lik e ly , o r m in im iz ed , and the r e c o ile d a to m is in a fo rm w hich is s e p a ra b le by c h e m ic a l a n d /o r p h y s ic a l m e a n s f ro m th e t a r g e t m o le c u le . T y p ic a l ex a m p le s of th is r e a c tio n inc lude th e u s e of e th y l io d id e to p ro d u c e I 128 and p o ta s s iu m c h lo ra te to p ro d u c e C i3 6 ,3 8 _ i n th e f i r s t c a s e th e io d in e is s e p a r a te d by e x tra c tin g w ith w a te r , red u c in g it to I - , and p re c ip ita tin g it a s Agi. In the second c a se the ch lo rin e is s e p a r a te d by d i r e c t p re c ip i ta t io n of A gC l. T o u se th e S z ila rd -C h a lm e rs r e a c t io n e f f ic ie n tly th e s y s te m m u s t b e ch o se n to m in im iz e o r p re v e n t e n t i r e l y ex c h an g e b e tw e e n th e r e c o f le d p ro d u c t and th e ü h s t r u c k a to m s in th e o r ig in a l t a r g e t m o le cu le . H ow ever, even w hen su c h exchange i s e n tire ly p re v e n te d , r a d ia t io n d e c o m p o s itio n of th e t a r g e t ( fro m f is s io n g a m m a s , c a p tu re g a m m a s , o r n e u tro n c o l l is io n s w ith o th e r a to m s in th e ta r g e t ) r e le a s e s so m e s ta b le a to m s of th e p ro d u c t e le m e n t w hich u s u a lly ac co m p an y th e r e c o i le d s p e c ie s and a r e in s e p a ra b le f ro m it .

W h e reas in th e c la s s ic S z ila rd -C h a lm e rs r e a c tio n th e ta rg e t i s u su a lly a s in g le p h a s e , e i th e r a so lid o r a liq u id com pound o r a so lu tio n , th e se p a -


r a t io n b e in g ac co m p lish e d a f te r th e i r r a d ia t io n u su a lly by so m e s o r t o f e x t r a c t io n p ro c e d u re , i t is a lso p o s s ib le to i r r a d ia te a tw o -p h a se s y s te m so a r r a n g e d th a t th e p ro d u c t r e c o i ls out o f one p h a se in to th e se co n d . In su c h a s y s te m th e f i r s t p h a se m igh t be fine p a r t i c le s su sp e n d ed in e i th e r a so lid o r liq u id se co n d p h a s e . In th is c a s e th e s iz e of p a r t i c le m u s t be kep t s m a ll an d th e s u r f a c e /v o lu m e r a t i o h ig h in o r d e r to a llo w th e h ig h e s t p o s s ib le f r a c t io n of r e c o i l in g a to m s to e s c a p e . F u r th e r m o r e th e c o n c e n t r a t io n "of su c h p a r t i c l e s m u s t n o t be to o h ig h l e s t to o m a n y r e c o i l in g a to m s p a s s th ro u g h th e se co n d p h a s e , s t r ik in g and b eco m in g lo d g ed in a n o th e r p a r t i c le o f th e f i r s t p h a s e , r e s u l t in g in a r e d u c t io n o f th e n e t n u m b e r o f r e c o v e r ab le r e c o i ls . A lte rn a tiv e ly , th e sy s te m m ight c o n s is t of a s ta c k of th in fo ils sa n d w ich e d tig h t ly to g e th e r w ith th e tw o p h a s e s a l te rn a t in g ; ag a in co n s id e ra tio n s of g e o m etry and len g th of m e a n - fre e path of the re c o ilin g sp e c ie s r e q u i r e th a t th e f i r s t p h a s e be a s th in a s p o s s ib le and th a t th e th ic k n e s s of th e se c o n d p h a s e be eq u a l to o r so m e w h a t g r e a te r th a n the r e c o i l r a n g e o f th e p ro d u c t.

P o s t - i r r a d i a t i o n s e p a ra t io n m ay be m e c h a n ic a l (in th e c a s e of s ta c k e d f o ils ) , p h y s ic a l (m e ltin g th e se c o n d p h a s e and f i l te r in g th e f i r s t f ro m it) , o r c h e m ic a l (d is so lv in g th e se c o n d p h a s e and e i th e r (1) f i l t e r in g th e f i r s t p h a se fro m it o r (2) d ire c tly e lec tro p la tin g o r e x tra c tin g the re c o ile d sp e c ie s f ro m th e s e c o n d p h a s e w ithou t r e m o v a l o f th e f i r s t p h a s e i f th e l a t t e r is i n e r t and no c h e m ic a l ex ch an g e ta k e s p la c e in th e p r o c e s s ) . D ep e n d in g on th e s y s te m , w a x e s , o i ls , c e r a m ic s , m e ta l s , in o rg a n ic s a l t s and o x id e s , io n -e x c h a n g e m a te r i a l s , e tc . , m a y b e u s e d fo r th e v a r io u s p h a s e s .

Iso to p e s e p a r a t io n u ti l iz in g d if fe r e n c e s in a n c e s to r h a l f - l iv e s

A n o th e r t r i c k w hich ca n be u se d fo r th e p ro d u c tio n of c e r ta in s e le c te d is o to p e s in a v i r tu a l ly c a r r i e r - f r e e s ta te w as f i r s t u se d by O V E R ST R E E T and JACOBSON [28] in 1944 and a few m o n th s l a t e r by D ILLA R D , ADAMS, FINSTON, and TURKEVICH [29] a s a m e an s of iden tify in g and c h a ra c te r iz -r in g n e w ly -d is c o v e re d d e s c e n d a n ts o f s h o r t - l iv e d f is s io n p ro d u c t k ry p to n s and x e n o n s . T h e o r ig in a l te c h n iq u e c o n s is te d of a r r a n g in g c o n d itio n s so a s to sw eep out g a s e o u s f is s io n p r o d u c ts f ro m a s u i ta b le t a r g e t d u r in g r e a c to r i r r a d ia t io n and to p a s s th e s e g a s e s along a c h a rg e d w ire . T he d e s c e n d an ts o f th e ra d io a c tiv e g a s e s w e re found d ep o s ite d in v a r io u s p la c e s along th e c h a rg e d w ir e , th e p o s it io n b e in g d e te r m in e d by th e h a l f - l iv e s of th e p a r e n t r a d io a c t iv e g a s e s and th e d e g re e of s e p a r a t io n b e in g a fu n c tio n of th e f lo w -ra te of th e g a s . T h is d ev ice m ad e u s e of th e fa c t th a t th e n a s c e n t d au g h te r of th e g aseo u s ra d io iso to p e is fo rm e d w ith an e le c tr ic c h a rg e w hich a t t r a c t s th e io n to th e w ire w h ere it d e p o s its and d e c a y s in to o th e r d e s c e n d a n ts . F o llo w in g th e i r r a d ia t io n , th e w ire w as c u t in to s e v e r a l s e c t io n s , e a c h of w h ich w as p r o c e s s e d c h e m ic a l ly to r e c o v e r th e d e s i r e d p ro d u c ts .

W ith th is tech n iq u e it should be p o s s ib le to m ake iso to p e s lik e Y 9 0 , S r 89, R b 88, B a i 3 9 , L a W O , C e i 4 i , and C e i 4 3 e s s e n t i a l ly f r e e of o th e r s ta b le and r a d io a c tiv e iso to p e s of th e s a m e e le m e n t. A lso iso to p e s w ith s im i la r h a lf- l iv e s , e .g . 1 8 -m in Rb88 and 1 5 -m in Rb89, c a n b e s e p a r a te d r e a d i ly f ro m each o th e r (note the d if fe re n t p a re n t h a lf - liv e s : K r 88 2.8 h and K r 89 3.2 min),

T h is te c h n iq u e ca n b e expanded to in c lu d e s e p a r a t io n of o th e r iso to p e s w hich d esce n d fro m a n a tu ra lly ra d io a c tiv e g a s , su c h a s rad o n . It m ig h t a lso be

16 L. G. STANG, JR.

u se d in c e r ta in c a s e s invo lv ing d e s c e n d a n ts of g a se o u s m o le c u le s m ad e r a d io a c tiv e a r t i f ic ia l ly . F o r exam ple , c a r r i e r - f r e e io d in e -131 m igh t be p re p a re d by p a s s in g ra d io a c tiv e hydrogen tellurideC?) along a c h a rg ed w ire and is o la tin g th e lia i f ro m th e e a r ly p o r t io n of th e w ire . B e c a u s e o f th e r e la t iv e ly lo n g p a r e n t h a l f - l iv e s in v o lv e d , th is p a r t i c u l a r e x a m p le w ill b e q u ite in e f f ic ie n t (i. e . w ill in v o lv e w a s tin g m u c h of th e 113* in o r d e r to a c h ie v e a f a i r ly p u r e p ro d u c t) and i s c i te d h e r e m o r e fo r th e s a k e of c o m p le te n e s s and fo r s tim u la tin g o th e r id eas r a th e r than as a p r a c tic a l p roduction p ro c e s a C a r r i e r - f r e e 1 13i would a c tu a lly be m uch b e t te r p re p a re d by th e i r ra d ia t io nof h ig h ly -e n ric h e d Tei30 .

T h e c h a rg e d w ire te c h n iq u e i s r e a l ly on ly one e x a m p le of a m o re g e n e ra l p r in c ip le , n am e ly , th e s e p a r a t io n and is o la tio n of d e sc e n d a n t i s o to p e s by m ak in g u se of d if fe re n c e s in th e h a l f - l iv e s of a n c e s to rs , w h a te v e r th e m e a n s of s e p a ra tio n a re .

F o r ex am p le , in s te a d of a ch a rg ed w ire , one m igh t u se an ion -exchange r e s in , e l e c t ro p h o r e s is , c h ro m a to g ra p h y , e le c tro c h ro m a to g ra p h y , o r co n c e iv a b ly ev en s o lv e n t e x tra c tio n . In su c h c a s e s th e a n c e s t r a l iso to p e n ee d n o t b e a g a s b u t c a n b e in liq u id o r s o lu t io n fo rm . W h a te v e r th e s y s te m , th e c r i t e r i a f o r s u c c e s s fu l o p e ra tio n a r e (1) th a t th e a n c e s to r h a l f - l iv e s be s h o r t enough so th a t a ll o r a t l e a s t a m a jo r f ra c tio n of th e im p o r ta n t one w ill h av e d ec ay e d d u r in g i t s p a s s a g e th ro u g h th e s y s te m o r , a l te rn a t iv e ly , th a t a l l o th e r a n c e s t r a l h a l f - l iv e s e x c e p t th e im p o r ta n t one a r e s h o r t , in w h ich c a s e th e d e s i r e d d e s c e n d a n t (but no o th e rs ) p a s s e s e n t i r e ly th ro u g h th e s y s te m ; (2) th a t th e s y s te m i s c h o s e n so th a t th e a n c e s to r e le m e n t o r co m p o u n d i s n o t a d s o rb e d o r h e ld up d u r in g p a s s a g e th ro u g h th e s y s te m , b u t th a t th e d a u g h te r i s f i rm ly fix ed a t th e s i te a t w h ich i t o r ig in a te s , and(3) th a t th e r e a r e su ff ic ie n t d if fe re n c e s be tw een th e h a lf - l iv e s of th e a n c e s t o r s to p e r m i t s e p a r a t io n o f th e d e s c e n d a n ts in t im e o r in s p a c e .

One can co n ce iv e of su ch s y s te m s o p e ra tin g con tinuously u s in g m a te r ia l b e in g c o n tin u a lly d is c h a r g e d f ro m a r e a c to r o r e v e n c i r c u la te d in to , out of, and b ack in to a r e a c to r ; o r one can co n ceiv e of th e s e s y s te m s o p e ra tin g b a tc h -w ise on p re v io u s ly - i r r a d ia te d m a te r ia l .

S om e e x a m p le s of iso to p e s w hich cou ld be m ad e by su c h p r o c e s s e s in c lude 5 7 -m in Sc49:(from c a lc iu m ), 3 9 -h A s77 (fro m g e rm a n iu m ), 3 6 -h R hios ( fro m ru th e n iu m ), 7 .5 -d A g in ( fro m p a lla d iu m ), 8 -d 1131 ( fro m te l lu r iu m ) , 13 .8 -d P r 143 (fro m c e r iu m ) , 2 .6 5 -y r Pm l47 , 5 0 -h Pmi49 , 2 7 - h P m i 5 i , and 8 0 -y r S m i5i ( a l l fro m neodym ium ), 1 .7 -y r E u i55(from sa m a riu m ), 7 .1 -d T b 161 (fro m g ad o lin iu m ). Hoi®3 and 1 .9 -y r Т т Ш (from e rb iu m ), 6 .8 -d L u i?7 (from y tte rb iu m ) , and 3 .1 5 -d Aui99 (fro m p la tin u m ).

In e a c h of th e s e c a s e s th e iso to p e p ro d u c e d co u ld b e v i r tu a l ly f r e e of o th e r iso to p e s of th e s a m e e le m e n t, and it is im p lied in th e above ex am p les th a t th e n a tu r a l ly - o c c u r r in g a n c e s to r co u ld b e u s e d , a lth o u g h in m a n y of th e c a s e s it w ould be m o re p r a c t ic a l to u se s tra ig h tfo rw a rd i r ra d ia tio n o fth e e n r ic h e d o r s e p a ra te d a n c e s t r a l iso to p e . It shou ld be p o in ted out aga in th a t th e s e p r o c e s s e s a r e no t n e c e s s a r i ly b e in g ad v o c a ted a s th e b e s t m e a n s of p ro d u c in g th e p a r t i c u la r e x a m p le s c i te d , but r a th e r th a t th e y m a y be u se fu l in s p e c ia l c a s e s w h e re th e h ig h c o s t of an i s o to p ic a l ly - s e p a r a te d t a r g e t ,

W H2T e. the T e being the radioactive part, m ade by reacting irradiated alum inium te llu ride withHCl.


to g e th e r w ith r e q u i r e m e n ts o f h ig h s p e c if ic a c t iv i ty o r h ig h r a d io i s o to p ic p u r i ty , m a k e o th e r m e th o d s u n s u ita b le . I t w ill b e r e a d i ly u n d e rs to o d th a t in m o s t c a s e s l ik e th e s e a b s o lu te is o to p ic s e p a r a t io n w ill n o t b e ac h ie v e d , b u t r a th e r th a t th e d e g re e of p u r i ty o r th e d e g re e of s e p a r a t io n w ill b e in v e r s e ly d e p e n d e n t u p o n th e m in im u m e f f ic ie n c y w h ic h c a n b e to le r a te d .

P a r e n t - d a u g h te r " m ilk in g " s y s te m s

A n o th e r u s e fu l te c h n iq u e o f a d if fe re n t n a tu re i s one in w h ich c e r t a in s h o r t - l iv e d r a d io is o to p e s c a n b e m a d e a v a ila b le f o r u s e a t c o n s id e r a b le d is ta n c e s f ro m th e r e a c t o r s in w h ich th e y w e re p ro d u c e d . T h is te c h n iq u e c o n s is ts o f d e v is in g a su ita b le , s y s te m w h e re b y th e d e s i r e d is o to p e c a n b e "m ilk e d " f ro m a lo n g e r - l iv e d p a re n t; th e p a re n t-d a u g h te r e q u ilib r iu m m ix tu r e i s w hat i s a c tu a lly sh ip p e d r a t h e r th a n th e s e p a r a te d d a u g h te r i t s e l f .

T h e c la s s i c ex am p le of su c h a s y s te m i s th e 1 6 2 0 -y r R a 2 2 6 - 3.8-dR n222 s y s te m w h ich h a s b e e n u s e d f o r d e c a d e s , c h ie f ly by h o s p i ta ls an d r a d io lo g is ts , a s a m e an s of p re p a r in g rad o n " s e e d s " fo r th e ra p e u tic im p lan ta tio n . In th is s y s te m a so lu tio n of a rad iu m s a lt i s kep t p e rm a n en tly w ith in a c lo sed g la s s s y s te m so a r r a n g e d th a t th e ra d o n g as ca n be pum ped off p e r io d ic a l ly and u s e d to f i l l ho llow n e e d le s o r v ia l s . D u rin g W o rld W a r II h u n d re d s of c u r ie s of 1 2 .8 -d BaMO w e re p r e p a r e d and u s e d a s a c o n tin u in g s o u r c e o f 4 0 .2 -h L a i 4 0 h u n d re d s of m i le s f ro m th e p ro d u c tio n s i t e .

H o w e v e r , th e f i r s t c o m m e r c ia l a p p l ic a tio n o f s im p le r a p id m ilk in g s y s te m s , a s d ev ice s fo r m ak ing s h o r t- l iv e d iso to p e s av a ila b le , w as p robab ly th e 2 .3 -h 1132 " g e n e ra to r" developed and su p p lied by BNL in 1954 121, 23, 24, 30 , 31]. S in ce th e n su c h s y s te m s h av e b e e n d e v is e d f o r 6 - h T c 99m 123, 24, 3 0 ,3 1 ] , 2 .3 -m in A128(S)[34], 6 5 -h Y90[23, 31 , 33 , 34, 35] , an d 6 8 -m in Ga68 [36 ,37], a l l a t BN L. E lse w h e re s y s te m s have b een d ev ised fo r 2 .6-m inB ai37 (from 3 0 -y r C s i 3 7 ) and 4 0 -h L a^o , am ong o th e rs [38] .

T h e a d v a n ta g e s of s u c h s y s te m s a r e n u m e ro u s . I f th e p a r e n t i s s u f f ic ie n t ly lo n g - l iv e d , th e d e v ic e m a y b e sh ip p e d g r e a t d is t a n c e s . F o r in s ta n c e , 2 .3 -h I132 (and i t s 7 7 -h Т е132 p a r e n t) h av e b e e n sh ip p e d f ro m B N L (New Y o rk ) to D e n m a rk , S w eden , A u s t r a l i a and B r a z i l an d 6 5 -h Y90 (and i t s 2 8 - y r S r 90 p a r e n t ) h av e b e e n sh ip p e d to J a p a n . E v e n 2 .3 -m in A l23 (9) ( to g e th e r w ith i t s 2 0 .8 8 -h M g28 p a re n t) have a l re a d y b ee n sh ip p ed to a p o in t 100 m ile s d is ta n t , a lth o u g h th is s y s te m h a s on ly r e c e n t ly b ee n m a d e a v a ilab le .

E v en w hen th e h a lf - l if e is long enough to p e r m i t d i r e c t sh ip m en t of th e d a u g h te r , th e s e g e n e r a to r s p ro v id e th e u s e r w ith a c o n tin u in g s o u r c e of th e d au g h te r in h is own la b o ra to ry , e lim in a tin g o r m in im iz in g th e p ro b le m s o f sch ed u lin g and h an d lin g re p e a te d s h ip m e n ts , and of d o v e ta ilin g th e i r a r r i v a l w ith o th e r s c h e d u le s im p o s e d by th e n a tu re of th e e x p e r im e n ts to b e p e r fo rm e d . P ro d u c tio n and sh ip m en t of a s in g le g e n e ra to r i s obv iously l e s s c o s t ly , b o th in t e r m s o f la b o u r and t r a n s p o r ta t io n c h a r g e s , th a n m u lt ip le

(8) „lust before this Sem inar A .J . Weiss of BNL re -determ ined th e h a lf-Ufe o f pure Al to be 2 .2381

0.006 m in .

See Footnote (8 ) .(9)

18 L. G. STANG, JR.

sh ip m e n ts of th e s e p a r a te d d a u g h te r . F u r th e r m o r e a sh ip m e n t c a n o ften b e m a d e by so m ew h at s lo w e r and hen ce l e s s ex p e n siv e m e a n s , and d e la y s in t r a n s i t a r e l e s s s e r io u s .

P a r a s i t i c i r r a d ia t io n s

O p e ra to rs of s m a ll r e s e a r c h r e a c to r s (and a c c e le r a to r o p e r a to r s too) sh o u ld b e a w a re of th e p o s s ib i l i t i e s o f u t i l iz in g w hat m ig h t b e te r m e d p a r a s i t ic i r r a d ia t io n s . I r e f e r not to th e i r r a d ia t io n of m o re th a n one ta rg e t in th e s a m e c o n ta in e r , a lth o u g h th is i s o f te n a l s o a u s e fu l te c h n iq u e , but r a th e r to i r r a d ia t io n s w hich a r e e n t i r e ly in c id e n ta l to th e p r im a r y p ro d u c t io n o r to th e o p e ra tio n of th e m a c h in e . F o r e x a m p le , a l lo y s c o n ta in in g a h ig h p é rc e n ta g e of i r o n , w h ich had r e c e iv e d a lo n g in te g r a te d i r r a d ia t io n , e i th e r a s c o n ta in e rs fo r o th e r t a r g e t s o r a s s t r u c t u r a l p a r t s o f th e r e a c to r , c a n b e a u s e fu l s o u r c e of r e la t iv e ly h ig h s p e c if ic a c tiv i ty Fe55 an d Fe59 and, depending on th e p u r ity of th e iro n in it ia l ly , c a r r i e r - f r e e Mn54. N ickel- b e a r in g a llo y s a r e u se fu l s o u r c e s of N i63. P ie c e s of a lu m in iu m w h ich , fo r w h a ts o e v e r r e a s o n , h av e b e e n e x p o sed to a n e u tro n ñ u x fo r a s u f f ic ie n tly lo n g t im e , m a y b e p o te n tia lly u s e fu l s o u rc e s o f A l26 (by m e a n s of th e A l 27 (n, 2 n )A 1 2 6 r e a c t io n ) , a lth o u g h th e s p e c if ic a c tiv i ty w ill b e so low [39] th a t 1 f u r th e r iso to p ic s e p a ra tio n ( e .g . e le c tro m a g n e tic ) would p ro b a ly be needed . S im ila r ly , b e r y l l iu m u s e d a s a m o d e ra to r f o r a lo n g t im e a t s u f f ic ie n tly h ig h flux: co u ld p ro v id e u s e fu l q u a n t i t ie s o f B e io , a lth o u g h , a s in th e A126 c a s e , f u r th e r is o to p ic s e p a r a t io n m ig h t be n e c e s s a r y . A lthough a l l th e i s o to p e s ju s t m en tio n ed a re m uch too lo n g -liv e d to be inc luded w ith in th e scope of th is S e m in a r , n e v e r th e le s s th e i r p ro d u c tio n and th e p ro d u c tio n of o th e rs l ik e th e m by th is m e an s is m entioned b ecau se th ey can be u se fu l b y -p ro d u c ts fro m th e o p e ra tio n of s m a ll r e s e a r c h r e a c to r s .

C irc u la t in g " lo o p s"

T h e f in a l s p e c ia l p ro d u c tio n m ethod w hich I shou ld lik e to m en tio n co n c e r n s th e u s e o f c i r c u la t in g " lo o p s" in r e a c t o r s w ith w h ich to u t i l i z e th e r a d ia t io n f ro m u l t r a - s h o r t - l iv e d ra d io is o to p e s (having h a l f - l iv e s l e s s th a n 2 m in ). A lthough su c h ra d io is o to p e s a r e o b v io u sly u s e le s s a s co m m o d itie s to be sh ip p e d , n e v e r th e le s s th e te c h n iq u e h a s c e r ta in ad v a n ta g e s and p r o m is e s to b e one w h ich c a n in c r e a s e th e u s e fu ln e s s o f a r e a c t o r , e v e n a s m a l l one . In th i s te c h n iq u e an a p p ro p r ia te s o lu tio n i s p u m p e d th ro u g h a r e a c t o r and o u t in to a tu b e o r c o i l lo c a te d in th e s y s te m to b e i r r a d i a t e d , f ro m w h ich i t m a y be d is c a rd e d o r r e tu r n e d to th e r e a c to r . T h e s y s te m to be i r r a d ia te d m ig h t be a ch e m ic a l one (e .g . one fo r s tudy ing the p o ly m e r iz a t io n of p la s t ic s ) , a b io lo g ic a l one (e. g. one fo r study ing th e u se of ra d ia tio n a s a m e a n s of c o n tro llin g th e sp ro u tin g of p o ta to e s , s te r i l iz in g f l ie s , e tc . ), o r p h y s io lo g ic a l (e. g . s tu d y in g in a c o n tro l le d m a n n e r th e e f fe c ts o f r a d i a t io n -d e l iv e r in g im p la n ts on v a r io u s o rg a n s and p r o c e s s e s w ith in a liv in g o rg a n is m ) .

W h a te v e r th e s y s te m , su c h a loop h a s th e ad v an tag e th a t th e " s o u rc e " can be p re p a re d in advance , w orking w ith s t r ic t ly n o n -ra d io ac tiv e m a te r ia ls , and w hen a l l i s r e a d y th e r a d ia t io n m a y be su d d e n ly tu rn e d on by s ta r t in g

A REVIEW OF THE PRODUCTION OF "SPECIAL” RADIOISOTOPES 19

th e c i rc u la t in g pum p . T h is is o f p a r t i c u la r ad v an tag e w h ere d e l ic a te o r t e d io u s o p e ra tio n s a r e in v o lv ed in c o n s tru c tin g o r p o s it io n in g th e s o u r c e of r a d ia t io n . A n o th e r a d v a n ta g e i s th a t , by d e f in itio n , th e r a d ia t io n m a y b e tu rn e d off f a i r ly a b ru p tly by s im p ly s to p p in g th e c i r c u la t in g p u m p w ith o u t sh u ttin g down th e r e a c to r . In ad d itio n , in th e c a s e of an a c c id e n t w hich r e l e a s e s r a d io a c t iv e so lu t io n , th e s h o r t h a l f - l i f e m in im iz e s an y h a z a r d .

A n o th e r f e a tu re of th is te c h n iq u e i s th a t w ith in c e r ta in l im i t s th e r e e x i s ts so m e f re e d o m of c h o ic e a s to th e ty p e and e n e rg y o f r a d ia t io n w h ich m ay b e p ro d u ce d in th is m a n n e r . F o r ex am p le , th e u se of a so lu tio n of d y s p ro s iu m p ro v id e s r a d ia tio n w hich is p re p o n d e ra n tly ~ 1 0 0 -k eV g am m a fro m 7 5 - s Dyi65m (c o n ta m in a te d to so m e e x te n t w ith b e ta s and h a r d e r g a m m a s f ro m 2 .3 -h D y i 6 5 ) . On th e o th e r hand , th e u s e o f a so lu tio n o f s i l v e r p r o v id e s a v e ry h igh p e rc e n ta g e of 2 .7-M eV b e ta s ac co m p an ie d by ~5% 656-keV g am m as (both f ro m 2 4 -s Ag no ) and by ~ 1 0 % 1.77-M eV b e ta s and n eg lig ib le am o u n ts o f g a m m a s (fro m 2 .3 -m in Agios ). I s o to p e s c a n b e found y ie ld in g o th e r e n e r g ie s and o th e r d e g r e e s of p u r i ty of r a d ia t io n .

A M IEL [24] h a s even p ro p o sed the u se of su c h a pum ped loop to p r o v ide n eu tro n ir ra d ia t io n and, m o re sp e c if ic a lly , ir ra d ia tio n by fa s t n eu tro n s o f d i s c r e te e n e r g ie s (1 .2 M eV and 0.43 M eV ). In e f fe c t , A m ie l 's p r o p o s a l b e c o m e s a n o th e r n e u tro n " e n e rg y t r a n s f o r m e r " , s im i la r in so m e r e s p e c ts to th e L i6D m en tioned above. In h is p ro p o sa l a so lu tio n of lith iu m hydroxide i s to b e u s e d , th e r e a c t io n s b e in g L i 6 ( n , t ) H e 4 and O i8 (t,c r)N 17( - ,(3 ~ n )0 16 (the N 17 - to -O 16 d e c a y h a s a h a l f - l i f e o f abou t 4 s . A p a r t i c u la r ad v an tag e of su c h a d e la y e d -n e u tro n s y s te m l ie s in th e fa c t th a t i t sh o u ld p e r m i t i r ra d ia tio n by fa s t n eu tro n s re la t iv e ly f re e [40] of the gam m a ra d ia tio n u su a lly accom panying o th e r n e u tro n s .

S tab le t r a c e r s

In th e p re v io u s se c tio n u l t r a - s h o r t - l iv e d ra d io iso to p e s w e re m en tioned a s s o u r c e s of r a d ia t io n . T h e a d v a n ta g e of th e s h o r t h a l f - l i f e in th i s c a s e l i e s in th e fa c t th a t i t p e r m i ts th e ra d ia t io n to be tu rn e d on and off a t w ill. P a r e n th e t ic a l ly i t sh o u ld be n o te d th a t s ta b le p r e c u r s o r s o f u l t r a - s h o r t liv e d r a d io is o to p e s a r e u s e fu l in a n o th e r w ay in c o n n e c tio n w ith a s m a l l r e s e a r c h r e a c t o r , a lb e it n o t fo r p ro d u c tio n p u r p o s e s . In th e f i r s t p a r t o f th is p a p e r I r e f e r r e d to th e p ro n o u n ced e ffec t w hich th e h a lf - l if e h a s on th e n e t r a te of p ro d u c tio n of a c tiv ity . T he m agn itude of th is effec t is often o v e rlo o k e d . I t i s p o s s ib le to i r r a d i a t e a s a m p le in a r e a c to r fo r a few s e c o n d s and to b eg in coun ting i t w ith in a few seco n d s a f te r th e end of th e i r ra d ia tio n ; in s p e c ia l c a s e s s a m p le s c a n b e co u n ted w ith in a few m il l is e c o n d s . W hen th is i s done i t c a n b e sh o w n th a t c e r t a in e le m e n ts , su c h a s s i l v e r , d y s p ro s iu m , ind ium , and bo ro n , am ong o th e rs , can be u se d as s ta b le t r a c e r s [41]. U n d er su c h co n d itio n s th e a c tiv ity p ro d u ce d by th e s ta b le t r a c e r is so o v e r w h e lm in g ly g r e a t e r th a n a c t iv i t ie s p ro d u c e d by o th e r c o n s t i tu e n ts o f th e s a m p le th a t th e g r o s s sa m p le m ay b e coun ted d i r e c t ly w ithout c h e m ic a l s e p a r a t io n o r t r e a tm e n t and b a c k g ro u n d a c t iv i t ie s w ill b e n e g l ig ib le .

A lthôugh such app lica tions a r e obviously lim ite d to r a th e r sp e c ia l c a se s , th e a d v a n ta g e s o f fe re d a r e n e v e r th e le s s g r e a t enough to w a r r a n t c a ll in g a t te n tio n to th i s te c h n iq u e . O b v io u sly th e u s e of a s ta b le is o to p e p e r m i t s th e d u ra tio n o f an e x p e r im e n t to ex ten d o v e r an u n lim ite d p e r io d of t im e ,

20 L. G. STANG, JR.

and y e t a t an y t im e d u r in g o r fo llo w in g th e e x p e r im e n t a s a m p le m a y b e a n a ly se d fo r th e p a r t i c u la r t r a c e r in q u e s tio n w ith a n e a s e , a c c u ra c y , and s e n s i t iv i ty w h ich , depend ing upon th e p a r t i c u la r s y s te m u s e d , c a n b e co n s id e r a b ly g r e a t e r th a n th a t o f fe re d b y any o th e r m e a n s of d e te c tio n , in clud ing a m a s s sp e c tro g ra p h . T h is i s , of c o u rs e , a sp e c ia l fo rm of ac tiv a tio n a n a ly s is , th e g e n e r a l su b je c t o f w h ich i s c o v e re d in o th e r s e s s io n s of th is S e m in a r .

I t i s a ls o of i n t e r e s t to n o te th a t F IN ST O N , B IS H O P , and K IN SLEY [42] a r e u s in g th e L i6(n ,or)H 3 r e a c t io n to m e a s u r e th e th ic k n e s s of v e r y th in f i lm s of L i6 F . In t h e i r m e th o d a n e u tro n b e a m f ro m th e B ro o k h a v e n G ra p h ite R e s e a r c h R e a c to r i s allow ed to s t r ik e th e sa m p le , and th e r e s u l t in g t r i to n s and a lp h a s a r e co u n ted d i r e c t ly in a. p u ls e h e ig h t a n a ly s e r e m p lo y in g a s o lid s ta te d e te c to r .

SUMM ARY O F T H E C U R R EN T STA TU S O F B N L R E A C T O R -P R O D U C E D "S P E C IA L " R A D IO ISO TO PES

I shou ld l ik e to devo te th e r e m a in d e r o f th is p a p e r to a v e ry b r ie f su m m a ry of th e m e th o d s c u r r e n t ly in u se fo r th e p ro d u c tio n of " s p e c ia l" r a d io iso to p e s a t B N L , co n c lu d in g w ith a b r ie f m e n tio n of so m e h ith e r to u n p u b lish ed w o rk . T h is p r e s e n ta t io n i s l im i te d to is o to p e s f o r w h ich r e a c t o r (no t a c c e le r a to r ) i r r a d ia t io n i s u s e d .

Io d in e - 132

C a r r i e r - f r e e io d in e -132 [1 9 ,2 0 ,2 1 ,3 0 , 31 ,43] (2 .3 -h h a lf- life ) is d i s t r i bu ted th ro u g h o u t th e w o rld f ro m BNL in a d ev ice c a lle d a " g e n e ra to r " . T he g e n e r a to r i s s im p ly a 1 0 -m l bed of a lu m in a h a lf f illin g a g la s s v e s s e l , 2 2 -m m d ia m . X 85 m m h ig h , s u r ro u n d e d by an o u te r p ro te c t in g p la s t ic tu b e . T h e 7 7 -h Tei32 p a r e n t i s f i rm ly a d s o rb e d a s Т е О з ” on th e A120 3 . T h e 1132 can b e re m o v e d (o r "m ilk e d " ) by th e u s e r re p e a te d ly and a t w ill ( s e v e ra l t im e s a d ay a s d e s i r e d and f o r p e r io d s o f tw o w eek s o r m o r e , d ep e n d in g upon th e u s e r ’s r e q u ir e m e n ts ) . E a c h m ilk in g r e q u i r e s on ly 5 m in and c o n s is t s o f s im p ly p o u r in g 15 m l o f v e r y d ilu te (0 .01 M )N H 3 s o lu t io n in to th e to p o f th e g e n e r a to r , th e p ro d u c t so lu tio n ru n n in g o u t o f th e b o tto m r e a d y fo r im m e d ia te u s e . T h e p ro d u c t co n ta in s l e s s th a n 0.001% ra d io a c tiv e te llu r iu m and , w hen m ilk e d d a ily , l e s s th a n 0.3% 1131.

T e l lu r iu m - 132

C a r r i e r - f r e e t e l l u r i u m - 132 [ 1 9 ,2 0 ,2 1 ,3 0 ,4 3 ] , a v a ila b le a s su c h in so lu t io n f o rm , o r a s th e s o u r c e o f I13¿ in a g e n e r a to r , i s o b ta in e d a s a p ro d u c t o f th e f is s io n of U235 . An a lu m in iu m -ja c k e te d s c ra p of an a llo y of a lu m in iu m and e n r ic h e d U235 , s im i la r to th e m a te r i a l c u r r e n t ly u s e d a s fu e l in th e B ro o k h av en G ra p h ite R e s e a r c h R e a c to r , i s i r r a d ia te d in th e r e a c to r and th en in tro d u c ed in to a p p ro p r ia te re m o te ly -o p e ra te d c h e m ic a l p r o c e s s in g eq u ipm en t in a h o t c e ll . T he sa m p le is co m p le te ly d is so lv e d in HNO3

c a ta ly s e d by H g. T h e so lu tio n is d ilu te d w ith w a te r and a llo w ed to flow by g ra v ity th ro u g h a co lum n of p ow dered ch ro m a to g ra p h ic a lu m in a , w hich a c ts


as an ion ex c h an g e r re ta in in g only te l lu r iu m and m olybdenum a s Т еО з and M0Ó4 io n s , r e s p e c tiv e ly , and allow ing th e o th e r f is s io n p ro d u c ts , to g e th e r w ith the U and th e Al to p a s s th ro u g h th e co lum n. A fte r w ash ing th e a lu m in a w ith w a te r th e m o lybdenum is e lu ted w ith 1 M NH4OH, fo llow ing w h ich th e te l lu r iu m is e lu te d w ith 3 M N aO H . T h e e n t i r e o p e ra t io n r e q u i r e s ab o u t 5 h and p ro d u c e s c u r ie am o u n ts o f Т е 13'2 (and M o99 ) w ith a c h e m ic a l y ie ld of 70%.

M o ly b d e n u m -99 and T e c h n e tiu m -9 9 m

C a r r i e r - f r e e M o " ( 6 7 - h h a l f - l i f e ) , o b ta in ed by th e above p r o c e s s [19, 20 ,3 0 ] w ith a r a d io c h e m ic a l p u r i ty o f >99.99% , i s a v a ila b le [43] a s su c h in so lu tio n fo rm o r in a g e n e r a to r f ro m w h ich i t s 6 -h c a r r i e r - f r e e , h ig h - p u r i ty T c 99m d a u g h te r ca n be m ilk ed [19, 20, 30, 31] by th e u s e r re p e a te d ly , and a t w ill . T h e g e n e r a to r in th is c a s e i s th e s a m e a s th a t u s e d fo r I*32, excep t th a t in th is c a s e only 5 m l of a lu m in a is u se d and th e m a n n er of m ilk in g i s n e a r ly id e n tic a l , th e on ly d if fe re n c e b e in g th a t T c 99m is e lu ted w ith 20 m l of 0.1 M HNO3 o r H C l. O bv iously , s in c e th e h a lf - l iv e s a r e som ew hat d if f e r e n t , th e k in e t ic s fo r f o rm a tio n o f th e tw o d a u g h te r s a r e so m e w h a t d if fe re n t, th e I132 r e q u ir in g abou t 12 h to r e a c h t r a n s ie n t e q u ilib r iu m fo llow ing a m ilk in g and th e T c 99m r e q u ir in g abou t 33 h . (In ad d itio n , w h e re a s T e i 3 2 i s a d s o rb e d onto th e a lu m in a a t a pH of 3 -5 , th e M o99 i s f ixed to th e a lu m in a a t a pH o f 1 -2 . ) B o th g e n e r a to r s a r e e x p e n d a b le , an d n o r e t u r n s h ip m e n t i s r e q u i r e d [43] .

Y ttr iu m - 90

C a r r i e r - f r e e y ttr iu m -9 0 of exceed ing ly h igh p u r i ty (10-6% Sr90 ) i s su p p l ie d by B N L in " g e n e r a to r " fo rm th ro u g h o u t th e w o rld [19, 33, 35, 43]. In

. th is fo rm th e p u r ity and sp e c if ic a c tiv ity a r e m uch h ig h e r th an could p o s s ib ly b e o b ta in e d th ro u g h th e i r r a d ia t io n of s ta b le y t t r i u m - 89. T h e u s e o f th e g e n e r a to r i s a ls o v e r y m u c h e a s ie r and , fo r r e p e a te d u s e , i s c o n s id e ra b ly c h e a p e r th a n o r d e r in g a l r e a d y - s e p a r a te d Y 90 [43, 44 , 45] . T h e g e n e r a to r in th is c a s e c o n s is t s o f a co lu m n of D ow ex 50W X 8 c a tio n ex c h a n g e r e s i n con ta ined in a g la s s tube betw een a p a i r of s in te re d g la s s d is c s and en c lo sed in a t r a n s p a r e n t p la s t ic c o n ta in e r w h ich s u p p o r ts and p r o te c t s th e g la s s a g a in s t b re a k a g e and s e r v e s a s a b e ta s h ie ld , th e o n ly s h ie ld in g r e q u i r e d fo r 100 m e of Y90. T h e p a re n t , 2 8 -y r Sr90 , is fixed to th e r e s in by p a s s in g a d ilu te HCl so lu tio n of i t o v e r th e r e s in . N

T o re m o v e th e Yau th e u s e r s l id e s open a d o o r in th e o u te r p la s t ic sh ie ld w h ich c a u s e s a d e l iv e ry tu b e to e m e rg e , u n d e r w hich any re c e iv in g v e s s e l m ay be p la ce d . One h undred m il l i l i t r e s of 0.5% c i t r ic ac id a t a pH of 5.5 a re th e n p o u re d in to th e to p o f th e g e n e r a to r . A bout 30 m in i s n e c e s s a r y fo r th is to p a s s th ro u g h , e lu tin g th e Y90 p ro d u c t a s a c i t r a te co m p lex . T h e g e n e r a to r m a y b e le f t u n a tte n d e d in a s m u c h a s a s p e c ia l " v a lv e " c o n s is t in g o f a p lug of p o w d ered q u a r tz on to p of th e g e n e ra to r au to m a tic a lly s to p s th e flow of liq u id (by m e a n s of c a p i l la r y a c tio n ) w hen th e le v e l o f added e lu e n t r e a c h e s th e v a lv e , th u s p re v e n tin g th e co lu m n f ro m d ry in g ou t.

T h e Y 90- c i t r a t e c o m p le x i s th e n r e a d y f o r im m e d ia te u s e o r , if n e c e s s a r y , th e c o m p le x m a y b e b ro k e n by an y one of f iv e p r o c e d u re s [35,

22 L. G. STANG, JR.

46] , ajad th e Y 90 th e n u s e d a s a c a tio n . In o r d e r to g u a ra n te e th e a b s e n c e o f m o r e th a n a n e g l ig ib le am o u n t o f S r90 c o n ta m in a tio n in th e p r o d u c t , a 5% a liq u o t o f th e p ro d u c t m a y b e r u n th ro u g h a n a u x i l ia r y a s s a y c o lu m n fu rn is h e d w ith e a c h g e n e r a to r [34, 43]. T h is a u x i l ia ry c o lu m n , lo a d e d w ith D ow ex 1 an io n ex ch an g e r e s in , r e t a in s n e a r ly a l l o f th e Y 90, a llo w in g any S r 9» to p a s s th ro u g h and b e d e te c te d . (D e te c tio n i s a c c o m p lis h e d by e v a p o ra tin g a p o r tio n of th is e ffluen t to d ry n e s s and th e n counting w ith and w ithou t 215 m g /c m 2 of added a lu m in iu m a b s o r b e r , a n am o u n t ju s t s u f f ic ie n t to s to p th e S r 90(but n o t th e Y90) b e ta s . T h e d if fe re n c e in co u n t, a f te r c o r r e c t in g fo r a b s o rb e r e ff ic ie n c y , i s due to S r 9<>). F ro m 100 m e of S r 9<>, th e am o u n t n o r m a l ly su p p lie d , 20 m e of Y9u c a n b e m ilk e d d a ily , o r l a r g e r am o u n ts a t l e s s f re q u e n t in te r v a ls .

F l u o r i n e - 18

C a r r i e r - f r e e , h ig h -p u r i ty F 18 ( h a lf - l i f e 1 0 9 .9 ± 0 .2 m in u te s [32]), th e on ly p r a c t ic a l t r a c e r fo r f lu o r in e , i s r e a d i ly p ro d u c e d in good y ie ld by th e r e a c t o r i r r a d i a t i o n of n a tu r a l L Í 2 C O 3 [10, 20, 21]. T h e r e a c t io n s a r e L ie (n ,t)H e 4 and 0 16(t, n )F 18. T h e m a te r ia l is p a c k e d in an a n n u la r s p a c e b e tw e e n th e w a ll o f an a lu m in iu m c o n ta in e r and an a lu m in iu m l in e r . A 10 -g s a m p le , p ac k ed th u s , p ro d u c e s a p p ro x im a te ly 30 m e of F 18 a f te r a o n e -n ig h t i r r a d ia t io n in a th e r m a l n e u tro n flu x of 1 0 1 3 n c m -2 s - l . U se o f e n r ic h e d L i b in c r e a s e s th e y ie ld p ro p o r tio n a te ly . T h e a n n u la r a r r a n g e m e n t i s u se d b e c a u se th e h igh c r o s s - s e c t io n of L i6 g re a tly d e p re s s e s th e in te rn a l n e u tro n flux a s th e s a m p le th ic k n e s s i s in c re a s e d . T h u s , th ic k s a m p le s w ould p r o duce l i t t l e , i f any , m o re ac tiv ity th a n th in ones and w ould be b u lk ie r to p r o c e s s .

T h e i r r a d ia te d L Í 2 C O 3 i s d is s o lv e d in H C l and th e s o lu t io n p a s s e d th ro u g h a s m a l l co lu m n o f c h r o m a to g ra p h ic a lu m in a w h ich h a s b e e n p r e c o n d itio n e d w ith 0.5 M H C l and w a sh e d w ith w a te r . T h e a lu m in a r e t a in s th e F 18, allow ing H 3 and ca tio n ic co n tam in an ts f ro m im p u r it ie s in th e ta rg e t m a te r ia l to p a s s th ro u g h w hen th e co lum n is w ashed [43] . E lu tio n w ith 0.1 M NaOH re m o v e s o v e r 95% of th e F ' 8 a s an a lu m in iu m f lu o rid e co m p lex . T h e F 18 m a y b e u se d in th is fo rm o r m a y be f re e d f ro m th e a lu m in iu m corrfplex by d is t i l l a t io n f ro m 18 N H 2 S 0 4 and c o l le c t io n in d ilu te N aO H [47] .

Io d in e - 133

C a r r i e r - f r e e io d in e - 133 (2 1 -h h a l f - l i f e ) i s th e on ly " s p e c ia l" r a d io iso to p e p re s e n t ly av a ila b le f ro m BNL in l e s s th an n e a r ly 100% rad io c h e m ic a l p u r i ty [43]. P ro d u c e d a s a p ro d u c t o f th e f is s io n of U233 , i t is co n tam in a te d to so m e ex ten t w ith o th e r f is s io n -p ro d u c t io d in e s . H ow ever by u s in g a r e l a tiv e ly s h o r t (24 -h ) i r r a d ia t io n th e b u ild -u p of 8 - d I 131 i s m in im iz e d . T h e sa m p le is p r o c e s s e d r a p id ly , im m e d ia te ly upon re m o v a l f ro m th e r e a c to r , and i s sh ip p e d s o a s to b e r e c e iv e d by th e u s e r w ith in 24 h f ro m th e end of the ir ra d ia t io n . F o r th e f i r s t 30 h a f te r i r ra d ia tio n the sh o r t- liv e d iodines, 2 .3 -h I 132 , 5 2 -m in I 134, and 6 .7 -h I 13S, a c co u n t fo r a s iz e a b le f r a c t io n of th e to ta l iod ine ac tiv ity . H ow ever, a t 30 h I 132 and I 134 a r e n eg lig ib le , w hile 1 1 Э5 and 1131 a c c o u n t fo r 14% and 8 %, r e s p e c t iv e ly , and I 133 a c c o u n ts fo r


th e re m a in in g 78% of th e to ta l io d in e a c tiv ity . F o r th e n ex t 40 h (i. e . u n til 70 h fo llow ing ir ra d ia t io n ) I 133 c o n s titu te s a t l e a s t 75% of th e to ta l a c tiv ity , w hile a t 105 h P 33 and I131 a c tiv itie s Eire about equal. T h e re is th u s a p e r io d of about '40 h when the I 133 i s su ff ic ie n tly p u re fo r a n u m b e r of e x p e r im e n ts to be p e r fo rm e d w ith i t .

T o in c r e a s e th e I I 33 r a d io c h e m ic a l p u r i ty s t i l l f u r th e r , so m e s o r t o f " c h a rg e d w ire " o r o th e r s im i la r te c h n iq u e , a s d e s c r ib e d above , co u ld be t r i e d w ith w h ich to e f fe c t f ra c t io n a t io n o f th e T e 131 and T e 133 p a r e n t s by v i r tu e of th e d if fe re n c e in h a l f - l iv e s b e tw e e n th e 2 2 -m in Sb131 an d 4 - m in Sbl33 g r a n d p a re n ts . S uch te c h n iq u e h e r e w ould u n d o u b ted ly b e q u ite d if f ic u l t and a p p lic a b le on ly in c a s e s w h e re th e n e e d fo r h ig h - p u r i ty I 1 33 i s v e ry g re a t . To m y know ledge su ch a fra c tio n a tio n techn ique fo r th is p a r t ic u l a r iso to p e has not ye t been t r ie d .

F iv e g r a m s of u ra n iu m o x id e (U3 O 8) a r e w ra p p e d in a lu m in iu m fo il and s e a le d in q u a r tz fo r th e i r r a d ia t io n , a f te r w h ich th e q u a r tz c a p s u le i s p la c e d in a d is s o lv in g v e s s e l and b ro k e n open r e m o te ly [19, 21]. S u lp h u ric ac id d is s o lv e s b o th th e A l and th e U3 O 8 . F o llow ing th e add ition of hyd rogen p e ro x id e to o x id ize rad io io d id e to e le m e n ta l io d in e , th e I 2 is sw ep t out w ith a s t r e a m of n itro g e n th ro u g h a c o n d e n se r and t r a p p e d in a s m a ll v o lu m e of d ilu te NaOH. T h e p ro c e s s in g tim e is about 30 m in and y ie ld s of about 150 m e I 133. a r e o b ta in ed as f ro m th e end of i r r a d ia t io n in a flux of 1013 n c m -2 s - i .

R a d io a c tiv e b ea d s

T h e u s e r u l t im a te ly r e c e iv e s e a c h of th e ab o v e is o to p e s in s o lu t io n fo rm , a lth o u g h in th e c a s e of th e g e n e r a to r s th e sh ip p in g f o rm i s th a t o f a dam p so lid . D ry so lid so u rc e s a re a lso av a ila b le . F o r exam ple , ch e m ic a lly and p h y s io lo g ic a lly in e r t so lid s p h e re s co n ta in in g abou t 1 m e of Y 90/m g of b ead , and ran g in g in d ia m e te r f ro m 0.5 to 2.0 m m , a re p re p a re d b y fu sin g a 50 w t. % m ix tu re of h ig h -p u r ity s ta b le y ttr iu m oxide and p r e - t r e a te d m on t- m o r i l lo n i te c la y [43]. T h e n a tu r a l c la y i s f i r s t le a c h e d w ith a s o lu t io n of NH4 NO 3 to r e p la c e th e C a ++, N a +, and K + w h ich a r e n o r m a l ly p r e s e n t in th e c la y and w h ich w ould g iv e r i s e to u n d e s i r a b le r a d io a c t iv i t ie s d u r in g su b se q u e n t n e u tro n i r r a d ia t io n [19]. T h e le a c h e d c la y i s o v e n -d r ie d b e fo re m ix in g w ith th e Y 2O 3 . T h e fu se d m ix tu re i s co o led and g ro u n d in to a f in e p o w d e r w h ich i s th e n lo a d e d in to s p e c ia l m o u ld s fo r r e - f u s in g in to b e a d s o f th e p r o p e r s iz e .

T h e m o u ld s a r e g ra p h i te b a r s in w h ich a n u m b e r of h o le s h av e b e e n d r i l le d , th e s iz e of w h ich d e te r m in e s th e am o u n t o f c la y m ix tu re w h ich i t w ill ho ld and h en c e th e s iz e of th e f in a l b e a d . A n e l e c t r i c c u r r e n t ¡passed th ro u g h th e g ra p h ite b a r ra p id ly h ea ts i t to the m e ltin g po in t of th is m ix tu re , about 1450°C, at w hich tim e th e pow der im m ed ia te ly c o a le sc e s in to a sp h e re . T h e coo led bea.ds a r e te s te d fo r ro u n d n e ss and p h y s ic a l s tr e n g th by ro llin g th e m b e tw e en p a r a l le l m e ta l b lo c k s . T h e s iz e i s ch e ck e d by p a s s in g th e m th ro u g h h o le s o f know n d ia m e te r . T h e b e a d s a r e th e n i r r a d i a t e d fo r th e ap p ro p ria te tim e s to give th e d e s ire d le v e l of Y 90 ac tiv ity . T he sa m e p ro c e d u re is u se d to p ro d u ce b ead s of o th e r s iz e s and con tain ing o th e r a c tiv i tie s , su c h as С s i34 o r L u i71.

24 L. G. STANG, JR.

M a g n e s iu m -28

A lth o u g h c a r r i e r - f r e e 2 1 -h M g28 c a n be m a d e in a c y c lo tro n b y th e A l27 (a .S pJM g2** r e a c tio n , o r by sp a lla tio n , and even though m o st of th e ex p e r im e n ts being p e r fo rm e d w ith M g28 r e q u ir e th e h ig h e s t p o s s ib le sp e c if ic a c tiv ity , n e v e r th e le s s a c c e le r a to r p ro d u c tio n w ould be v e ry ex p e n siv e and co u ld n o t e a s i ly p ro v id e th e q u a n t i t ie s c u r r e n t ly in d e m a n d in th e U n ite d S ta te s . U n lim ited q u an titie s a r e b e in g p ro d u ce d in th e B rookhaven G rap h ite R e s e a r c h R e a c to r a t a r e a s o n a b le c o s t of $70 /5 0 m c[4 3 ] by i r r a d ia t io n of th in fo ils of an a llo y of e n r ic h e d L i6 and en ric h e d Mg 26 t th e re a c tio n s being L i 6(n ,tJH e4 and Mg ^ ( t .p J M g 28 [21]. T h e " th ic k ta rg e t" c r o s s - s e c t i o n fo r th is ( t ,p ) r e a c t io n h a s b ee n d e te rm in e d to be 8 m b fo r < 2 .7 3 -M e V t r i to n s [48].

T h e u s e of li th iu m , e n r ic h e d to 95% L i 6, g iv e s an a p p ro x im a te ly te n fo ld in c r e a s e in s p e c if ic a c tiv i ty o v e r th a t o b ta in e d w ith n a tu r a l l i th iu m , w h ile th e u se of m a g n e s iu m e n r ic h e d to > 99% M g 2 6 in c r e a s e s th e sp e c if ic a c tiv i ty about th ir ty - f o ld o v e r th a t o b ta in ed w ith n a tu ra l m a g n es iu m . T h u s , i r r a d ia t io n in a th e rm a l n e u tro n flux of about 1013n cm -2 s ' 1 fo r th r e e days y ie ld s ab o u t 40 m e of M g ^ -A l28 1̂0) e q u i l ib r iu m m ix tu re p e r g r a m o f s ta b le m a g n esiu m . A lthough only a lim ite d s tudy of th e dependence of to ta l a c tiv ity and s p e c if ic a c tiv i ty on th e L i/M g r a t i o h a s b e e n m a d e , th e 75 w t.% L ie /2 5 w t.% Mg26 r a t io p r e s e n t ly u se d is a t l e a s t s a t is f a c to ry and p ro b ab ly o p tim u m . E n ric h e d Li6 i s r e c o v e r a b le and r e - u s a b le . A lthough th e ex p en s iv e (abou t $ 3 0 0 0 /g ) M g26 i s o b v io u s ly n o t r e - u s a b l e , n e v e r th e le s s on ly $ 8 w o rth of M g26 i s n e e d e d to m a k e 50 ¿ic of M g28 .

T h e a llo y i s m a d e b y m e lt in g th e l i th iu m in a g ra p h i te c r u c ib le in an i n e r t a tm o s p h e re and d is s o lv in g th e a p p ro p r ia te am o u n t o f m a g n e s iu m in i t w ith s t i r r in g . A fte r p o u rin g th e m o lten m e ta l in to a f la t m ould , and c o v e rin g th e co o led ingo t w ith m in e r a l o il, th e m e ta l i s r o l le d to a th ic k n e s s of0.25 m m and c u t in to s t r i p s o f th e a p p ro p r ia te s iz e and sh a p e . T h is th ic k n e s s p ro v id e s su ffic ie n t m e c h a n ic a l s tre n g th fo r hand ling w ithou t s e r io u s ly d e p r e s s in g th e in te r n a l n e u tro n flu x (w hich d e p r e s s io n w ould r e d u c e th e s p e c if ic a c t iv i ty o b ta in a b le ) . A s a f u r th e r p re c a u t io n a g a in s t , d e p r e s s in g th e in te r n a l n e u tro n f lu x , g ra p h i te s p a c e r s a r e u s e d d u r in g i r r a d ia t io n to s e p a ra te ad jac en t fo ils . O xidation of th e fo ils is p rev e n ted by an in e r t a tm o s p h e re in a s e a le d a lum in ium ir ra d ia t io n can .

F ollow ing ir ra d ia t io n , th e fo ils a r e d is so lv ed in w ater, and the Mg28 (OH)2 w h ich fo rm s is c e n tr ifu g e d , w ash e d w ith w a te r , d is s o lv e d in H C l, and p a s s e d th ro u g h c h ro m a to g ra p h ic a lu m in a , fo llo w ed by D ow ex 1 an io n exchange r e s in . T h e efflu en t is ev a p o ra te d a lm o s t to d ry n e s s s e v e ra l t im e s t o re m o v e t r i t i u m . A bout 2 o r 3 h a r e r e q u i r e d , and th e c h e m ic a l y ie ld i s ab o u t 95% [19 ,22 ].

R e s e a rc h is in p r o g re s s a t BNL re g a rd in g th e p o ss ib ili ty of u sing re c o il te c h n iq u e s to p ro d u c e c a r r i e r - f r e e M g28 in th e r e a c t o r . B o th c l a s s i c a l S z i la r d -C h a lm e r s r e a c t io n s and th e i r r a d ia t io n o f h e te ro g e n e o u s s y s te m s of tw o so lid p h a s e s a r e u n d e r study . A lthough it is expected th a t th e r e s u l t s o f th is w o rk w ill n o t lo w e r th e p r e s e n t p r i c e o r p ro v id e g r e a t e r to ta l a c tiv i ty , i t is hoped th a t th e y w ill p ro v id e th e b a s is fo r a ch e a p e r c a r r i e r - f r e e o r h ig h - s p e c i f ic - a c t iv i ty p ro d u c t th a n c a n b e m a d e in an a c c e le r a to r .


A lu m in iu m - 2 8

A lthough n o t h i th e r to announced p u b lic ly , e x c e p t in a p r o g r e s s r e p o r t {32j, A L L E N W EISS, a t B N L , r e c e n t ly d ev e lo p ed an u l t r a - r a p id " m ilk in g " s y s te m , b y m e a n s o f w h ich c a r r i e r - f r e e 2 .2 8 -m in Al'28 (10)c a n b e m a d ea v a ila b le fo r r e p e a te d u s e h u n d re d s of m ile s f ro m th e p ro d u c tio n s i t e . T h e h e a r t o f th is s y s te m i s a D ow ex 50W X 8 c a t io n e x c h a n g e r e s i n c o lu m n on w h ich th e 2 1 -h M g 2 8 p a r e n t i s a d s o rb e d . A 128 (11) i s e lu te d w ith abou t 2 m l of 1 N NaOH in 10-30 s . T h e g e n e ra to r l ife i s w e ll o v e r 1 5 0 m ilk in g s .D u rin g u s e th e p u r i ty o f th e A l28 i n c r e a s e s f ro m 99.95% to > 99.999% .

F o r th i s g e n e r a to r u l t r a - p u r e M g28 i s r e q u i r e d , an d th i s i s o b ta in e d by re m o v in g a s su lp h id e m in u te t r a c e s of Cu64 and C diis n o rm a l ly p r e s e n t in ' 'c o m m e rc ia l" M g2® d e s c r ib e d in th e p re c e d in g s u b -s e c tio n . In c id en ta lly , th e h a l f - l i f e o f su c h u l t r a - p u r e Mg28 h a s b ee n r e - d e te r m in e d to b e 2 0 .8 8 ±0.06 h [49] , w hile th a t fo r Al® (12) h as b een re -d e te rm in e d a s 2.28 ± 0 .0 1 m in P2] .

S cand ium -47

A lso to be announced so o n is th e a v a ila b ili ty [43] of m il l ic u r ie am oun ts of c a r r i e r - f r e e 3 .4 -d Sc47 . T h e p ro c e d u re d ev e lo p e d by R . F .D o e r iñ g and J . D aa n e a t B N L in v o lv e s th e i r r a d ia t io n o f r e a g e n t - g r a d e n a tu r a l C aO , d is s o lu tio n o f th e i r r a d ia te d m a te r i a l , c a r r y in g th e Sc47 on Fe(OH>3 , an d s e p a ra t io n of Sc47 f ro m F e +++v ia a Dowex 50WX 8 c a tio n exchange co lum n . N o g a m m a -e m it t in g im p u r i t ie s h av e b e e n d e te c te d in th i s p ro d u c t s o f a r .

L ith iu m - 6 d e u te r id e

E a r l i e r in th is p a p e r th e u s e of l i t h iu m - 6 d e u te r id e w as m e n tio n e d a s a m e a n s o f g e n e ra t in g u s e fu l f lu x e s o f m o n o - e n e rg e t ic 1 4 -M eV n e u t ro n s ' v ia th e L i6 (n , t)H e4 and H2(t, n)H e4 r e a c t io n s . L ith iu m -6 d e u te r id e w as p r e p a r e d [18] by p a s s in g d e u te r iu m g a s Ç> 99% H2) o v e r m o lte n l i th iu m m e ta l (e n r ic h e d to 95% L ie ) a t 700°C. T h e p ro d u c t i s p r e s s e d in to p e l l e t s u s in g 100 t / in 2 in a d ry a tm o sp h e re . W hile f in a lly -d iv id ed lith iu m h y d rid e i s h ighly r e a c tiv e in m o is t a i r , and can even exp lode, a p r e s s e d p e l le t of Li6D can b e h e a te d to 200°C in a i r b e fo re i t w ill ig n ite , and p e l le ts have b ee n h e a te d to 400°C u n d e r h e liu m w ithou t d ec o m p o s itio n .

A u s e fu l a s s e m b ly w h ich c a n be u se d ro u t in e ly a s a s o u rc e o f 1 4 -MeV n e u tro n s c o n s is ts o f a 0 .5 - in -d ia m . X 0 .5 -c m - th ic k p e l le t of L i6D w ra p p e d

. in a n a lu m in iu m fo il and s e a le d u n d e r v a c u u m in a 1 -m m - w a l l q u a r tz am p o u le . S am p le s to be b o m b a rd e d by f a s t n e u tro n s a r e a tta c h e d to th e f la t s id e of th is am pou le o r ca n be sandw iched b e tw een tw o su c h a m p o u les . Obv io u s ly , o th e r a r r a n g e m e n ts a r e o f c o u r s e f e a s ib le , b e a r in g in m in d th a t , fo r th e m ax im u m e m is s io n of f a s t n e u tro n s , th e o p tim um th ic k n e s s of L i6D i s ab o u t 0 .1 c m and th a t a t l e a s t 90% of th e m a x im u m f a s t n e u tro n f lu x i s a v a ila b le w ith th ic k n e s s e s b e tw e e n 0.04 and 0 .8 0 c m .

(10).(11).(12) SeeFootnote{8).

26 L. G. STANG, JR.

W ith su c h a p e l le t o f L iBD a v a lu e of 1.2X 10~4 w as o b ta in e d 13) fo r th e r a t io : 14 MeV n eu tro n flux p ro d u ced p e r am b ien t th e rm a l n eu tro n flux. T hus in a th e r m a l n e u tro n flux of 1013 n c m -2 s - i th e 1 4 -MeV n e u tro n flux f ro m L i6D w ill be 1 .2 X 109. F o r c o m p a r iso n , th e 14-M eV n e u tro n flux m e a s u re d a t th e s u r fa c e of a s in g le th ic k n e s s ' of fu e l p la te (14> of th e ty p e u se d in th e B ro o k h a v e n G ra p h ite R e s e a r c h R e a c to r w as 5X 108 w hen th e th e r m a l flux w a s 1013 . A lth o u g h th is m a y in d ic a te th a t th e L i6D i s m o r e th a n tw ic e a s good a s Ü235 fo r th e p ro d u c tio n of f a s t n e u t ro n s , i t m u s t b e r e m e m b e r e d th a t th e th ic k n e s s of th e L i6 D u se d w as n e a r ly o p tim u m , w h e re a s th e f a s t f lu x o b ta in ed f ro m th e fu e l p la te cou ld be in c re a s e d by a f a c to r of p e rh a p s 50 o r 60 by u s in g a th ic k e r p la te o f U 235 . O n th e o th e r h an d , in c r e a s in g th e am ount o f U235 can b e done only at th e ex p en se of hav ing to re m o v e p r o p o r t io n a te ly g r e a t e r am o u n ts o f h e a t , up to th e p o in t w h e re th e p ro b le m rb e c o m e s fo rm id a b le . W hen th e 14-M eV n e u tro n f lu x e s p ro d u c e d by L i6D and a BNL' fu e l p la te a r e n o rm a liz e d to th e s a m e h e a t g e n e ra tio n p e r u n it a r e a , i t i s found th a t th e L i6D p ro d u c e s ab o u t 150% o f th e flu x p ro d u c e d b y th e fu e l p l a t e .

An ad v an tag e of th e L i6D s o u rc e o v e r U235 l i e s in th e la c k of r e s id u a l r a d io a c tiv ity w hen th e so u rc e is w ithd raw n fro m th e r e a c to r . T hus a ta rg e t c a n b e a tta c h e d to a L i6D s o u rc e and th e w hole in s e r t e d and w ith d raw n a s a u n it . T h e u s e of U 235 in a s im i la r fa sh io n w ould r e s u l t in a r a d ia t io n and co n tam in a tio n p ro b le m , a lthough th is could be p re v e n te d in the c a s e of l a r g e r XJ235 c b n v é r te r s w hich m ig h t be le f t in p la c e in a r e a c to r w ith a p ro v is io n fo r in s e r t in g and w ith d raw in g a ta rg e t .

T h e f lu x a s 'c lo s e a s one c a n -g e t to a z i rc o n iu m t r i t i d e t a r g e t b e in g b o m b ard ed w ith 20 д а of 600-keV d eu te ro n s in th e B rookhaven Van de G raaff w a s found to b e 8 .3X 108 14-M eV n c m -2 s*1 (15) # n o t a p p re c ia b ly lo w e rth a n th a t p ro d u ced by the L i6D. H ow ever, when com p arin g the Van de G raaff and L i6D m ethods i t m u s t be re m e m b e re d th a t, w hile th e Van de G ra a ff has an advan tage in th a t few èr co n tam in a tin g a c tiv i tie s w ill u su a lly be p ro d u ced in the se co n d a ry ta rg e t , th e u se of L i BD o ffe rs the advan tages, noted e a r l ie r in 'th is p a p e r , of a r e a c to r ov er an a c c e le ra to r .

A C K N O W L E D G E M E N T

I am g r a te f u l to th e I n te rn a t io n a l A to m ic E n e rg y A gency f o r th e in v ita t io n t o s u b m it th is p a p e r . I r e g r e t th a t th e l im i te d t im e a v a ila b le fo r w r i t in g i t h a s p r e v e n te d m e f ro m m a k in g i t m o r e c o m p le te th a n i t i s . In p a r t i c u l a r '! sh o u ld p o in t ou t th a t th e l i t e r a t u r e w as n o t s e a r c h e d and f o r th i s r e a s o n th e R e fe r e n c e s a r e weak: and v e r y in c o m p le te .

BNL-5366R, (c ited [18] ) , actually gives 7 x'lfi"* for the ratio o f 14-M eV /therm al neutrons ob ta ined with I16D and proportionately lower values for the fluxes of 14-MeV neutrons obtained from Uzss and from th e Van de G raaff. However, th e se lo w e rv a lu esa reb ased o n a cross-section o f 30 m b for th e V ^ in , a ) Sc4® m onitoring reac tio n . When the be tte r value o f 18 mb [51] is used instead o f 30, the values c ited in the present paper a ie obtained .

(14), (15) See Footnote (13).


r e f e r e n c e s !16)

I [1] CUMMISKEY, С . , HA MILL, W .H . and WILLIAMS, R .R ., I t . , "C hem ica l Effects o f 8" D ecay from T e ISa to Ilte ” . I . Inorg. N ucl. C h em . 21 (1961) 205-209.

[2] RIESZ, P . and BIGELEISEN, J . , "Solvent Effect on a prim ary carbon bo tope Effect - Dec arboxy la tlon of Trlnitrobenzoate Ion In W ater and ethanol-w ater M ixture", J. Am. C hem . S o c ., (Ц (1959) 6187-9.

[3] BISHOP. W .N .. Unpublished m onthly progress report. Hot Laboratory D ivision, BNL(August, 1 9 6 2 ).[4] YOUNG, G .A . (co m p ile r) . Radiation A pplications and fission product U tiliza tion (A B ibliography o f

Selected Unclassified L iterature), ТШ -3046 (S uppl.2 ), (January, 1959) 187, (1300 references). O ffice o f T echnical Services, US D epartm ent o f C om m erce, Washington, DC.

[5] ROBERTS. R ., R ad iation -in itia ted Polym erization and G raft P olym erization , IAEA; V ienna, Review Series 13 (1961) 43 .

[6] C om pila tion of Abstracts dealing w ith th e Effect o f nuclear Radiation on Polym ers and fiber-fo rm ing M aterials. D ep t. .T ex tile R es., School o f T ex tiles , N . C aro lina S ta te C o l l . . Raleigh, N . C aro lina , USA.

f7] AUSTIN, J .C . , Bibl. on G am m a-R ay Radiogr. 1950 to 1961 in c . BNL 716 (L-326) (M arch , 1962).[8] PRENER, J .S . and WILLIAMS, F .E ., "The Activator Systems in zinc sulfide and halophosphatePhosphors",

J. Electrochem . S oc ., 103 (1956) 342.[9] GREENBERG, J . , SAWITSKY, A .. DUDLEY, H .C ., LEVY, R .N . and RAI, K .R ., Therapy of polycythem ia

Veta with Radioyttrium (Yi0) , J . N ucl. Med. 3 l ( I a n . , 1962) 18-25.[10] FARR, L.E. and YAMAMOTO. L. Y ., "Neutron C apture Therapy of a c e reb e lla r H em angiosarcom a

afte r su rg ical and rad ia tion T rea tm en t" , I . N ucl. M ed, , 2 4 (O c t . , 1961) 253-271 .[11] HARPER, P .V . , "C haracteristic and M anufacture o f Radioisotopes for m ed ica l Purposes a t th e Argonne

C ancer Research H ospital", Argonne Cancer Res. Hosp. Sem iannual Rep. to th e ABC, A C R H -14(Sept., 1960) 44 -49 .

[12] MEALEY, J . , J r .. ARONOW, S . , BROWNELL, G .L . and SWEET, W .H ., L ocalization o f fo ca l in tr a cran ia l Lesions by Scanning of Rays from positron-em itting Isotopes, TID-6210, Mass. Gen. Hosp. (1959) O ffice o f Technical Services, US Dept, of C o m m ., W ash., DC.

[13] BLAU, M . and BENDffi, M .A ., "Radiomercury (Hgi05) labe lled Neohydrin: A new Agent for brain tum or Localization", J. N ucl. M ed ., 3 2 (M a r . , 1962) 83 -93 .

[14] RAYTHEON MANUF. C o .. W altham , M ass., N uclear Reactor D a ta , (D e c ., 1956 ).[15] KOENIG, L .A ., MATTAUCH, J .H .E ., WAPSTRA, A .H . and EVERLING, F ., Consistent Set o f Energies

liberated in nuclear Reactions, N uclear Data Tables, Parts I and П (1 9 6 0 ). N uclear Data P roject, N at. Acad. S c ie .-N at. Res. Council, W ash., DC. (F eb ., 1961). See also: ASHBY, V .J. and CATRON, H .C ., Tables of N uclear Reaction Q V alues, Lawrence Rad. L ab., Univ. o f C a l i f . , Liverm ore, UCRL-5419 (F e b ., 1959).

[16] ROY, J .C . and HAWTON, J .J . , "Table o f estim ated Cross Sections for ( n ,p ) , (n, a ) and (n ,2n ) Reactions in a fission neutron Spectrum ", CRC-1003/AECL-1181, C halk River, O ntario , C anada (D e c ., 1 9 6 0 ).

[17] HUGHES, D .J . , P ile Neutron Research, Addison-W esly Publ. C o . (1953) 98.[18] WEISS, A .J . , TUCKER, W .D . and STANG, L .G ., J r ., "T he Use o f L ith ium -6 D euteride as a Source

of 14 MeV Neutrons in a N uclear R eactor” , BNL-5366R Is co m p le te pap er. Abstr. in T rans. A m erican N ucl. S o c ., 3 2 (D e c .,1 9 6 0 ) 536-537. See Footnote 13.

[19] RICHARDS, P . , "A Survey of th e Production a t Brookhaven N ational Laboratory o f Radioisotopes for m ed ica l Research", Estratto D egli A tti U fficiali D el V° Congresso N ucleare, Rome (June, 1960) .

[20] TUCKER, W .D ., GREENE, M .W ., WEISS, A .J . and MURRENHOFF, A ., M ethods o f Préparation o f som e c a rrie r-free Radioisotopes involving Sorption on A lum ina. BNL-3746 is co m p le te p ap er . Abstr. in T rans. A m er. N ucl. S o c ., 1 1 (June, 1958) 160.

[21] STANG, L .G ., J r ., TUCKER, W .D ., DOERING, R .F ., WEISS, A .J ., GREENE, M .W . and BANKS. H .O „"D evelopm ent o f M ethods for th e Production o f c e r ta in sho rt-lived Radioisotopes” , P roc. 1st UNESCO In t. C o n f . , Paris (1 9 5 7 ) . Also published in : Radioisotopes in Scientific Research, 1 Pergam on Press (1 9 5 8 ). . '

In these References BNL refers to Brookhaven N ational Laboratory, Upton, New York, USA. T he designation BNL- follow edby a number refers to a published report from Brookhaven N ational Laboratory.

28 L. G. STANG, JR.

[22] STANG, L .G ., J r ., TUCKER, W .D ., WEISS, A .J. and BANKS, H .O ., J r ., "Production and Availability of M ga ", BNL-3138. Presented a t i Ann. M tg. o f A m er. N ucl. S o c ., W ash ., D C ., (D e c ., 1956 ).

[23] RUDENKO, N .P . e t SEVASTIANOV, A .I ..« P ro d u c tio n du radioisotope bë ry llium -7 dans un réacteur n ucléaire suivant une réaction nucléaire s e c o n d a ire » . Traduction n" R1216, (2 .2 .1 9 6 1 ) par C entre ¿'É tudes Nucléaires de S a 'c lay de Radiokhim ia, SSSR1 6 (1959) 691-693.

[24] SAADIA AM1EL, Private com m unication .[25] HUGHES, D .J . and SCHWARTZ, R .B ., Neutron Cross Sections, 2nd e d . BNL-325 (July, 19 5 8 ).[26] KOUTS, H .J .C . , Neutron Physics of and with the High Flux Beam Research Reactor, BNL-664 (T-218)

(M arch. 1961).[27] FRIEDLANDER, G . and KENNEDY, J .W ., Nuclear and Radiochemistry, John Wiley and Sons, In c ., N .Y.

(1955) 468.[28] OVERSTREET, .R. and JACOBSON, L ., "Determination o f Gas Half-Lives by the charged-wire Technique",

Radiochem ical Studies: The Fission Products (C .D . C oryell and N. Sugarm an, Eds.) Book 2, Part V, paper 67, M cGraw-Hill Book C o ., (1951) 621-623.

[29] DILLARD, C .R ., ADAMS, R .M ., FINSTON, H . and TURKEVJCH, A ., "D eterm ination o f Gas H alf- Lives by the charged-w ire Technique", Radiochemical Studies: The Fission Products (C .D . C oryell and N . Sugarm an, Eds.) Book 2, Part V, paper 68, M cG raw-Hill Book C o ., (1951) 624-634 .

[30] TUCKER, W .D ., GREENE, M .W . and MURRENHOFF, A .P ., "Die Production von tragerfreiem Tellur-132, Jod-132, Molybdàn -99 und Tachnetium -99m aus neutronenbestrahltem Uran durch fractionierte Sorption an Aluminiumoxyd", Atompraxis 5 8 (M ai, 1962) 163-167.

[31] TUCKER, W .D ., DOERING, R .F ., GREENE, M .W . and STANG, L .G ., J r ., "P rac tica l Methods of M ilking Y 90, T c-99m , and 1-132 from their respective Parents", Trans. Amer. Nucl. S o c ., 3 2 (D e c ., 1960) 451.

[32] WEISS, A .J. and HILLMAN, М., Progr. Rep. Nucl. Engg. D ept., BNL, BNL-731 (S-61) (Jan .-A p r., 1962).[33] DOERING, R .F ., TUCKER, W .D . and STANG, L .G ., J r . . "A D evice for safely m ilk ing ca rrie r-free

Y® from S r ^ ”, BNL-4865. Presented a t Ann. M tg. o f Soc. o f N ucl. M ed., Estes Park, Colorado (June, 1960).

[34] DOERING, R .F ., TUCKER, W .D . and STANG, L .G ., J r ., "A rapid Method for the D etection o f Sr*°

C ontam ination in Y*®", J .Inorg . N ucl. C hem . 15 (1960) 215-221.

[35] DOERING, R .F ., TUCKER, W .D . and STANG, L .G ., J r .. ”A sim p le Process for M ilking Y " from Sr*6” , BNL (F e b .. 1957).

[36] GREENE, M .W ., Progr. Rep. N ucl. Engg D e p t., BNL, BNL-671 (S -58) ( J a n .-A p r . ,1 9 6 1 ) .[37] GREENE, M .W ., Progr. Rep. N ucl. Engg D e p t., BNL, BNL-659 (S -57) (S e p t .-D e e . , 19 6 0 ).[38] GREENE, M. W ., DOERING, R .F . and HILLMAN, М ., "A Review o f M ilking System s", BNL Report

(in press) •[39] RIGHTMIRE, R .A ., Long-lived Alum inum -26 (thesis), Carnegie Inst, o f Techn. , Pittsburgh, Pa. USAEC

Rep. NYO-6633 (June, 1957).

[40] LAURITSEN, T . and AJZENBERG-SELOVE, F . , "Energy Levels o f lig h t N uclei", N uclear D ata Sheets, sets 5 and 6, N at, A cad, o f S c ie ,, N at. Res,1 C ouncil, W ash., DC, (M ay, 1962).

[4 1 ] STANG, L .G ., J r . , "A ctivation Analysis for M edical Research: T he Use o f stable Silver as a T racer" , N at. Mtg of Soc. o f N ucl. M ed., Portland, O reg. (June, 1956).

[42] FINSTON, H .L ., BISHOP, W. N .. and KINSLEY, M .T . , Unpublished m onthly Prog. R ep ., Hot Lab. D iv ., BNL, (August, 1962).

£43] CATALOGUE OF PROCESSED ISOTOPES FROM BNL, (1 9 6 3 ), Hot Lab. D iv ., BNL.[44] INTERNATIONAL ATOMIC ENERGY AGENCY, International Directory o f Radioisotopes, 2nd E d., IAEA,

V ienna (1962).[45] SOMMERVILLE, J .L . (E d .) , The Isotope Index, Scie, Equipm. C o ., Indianapolis, Ind. USA(Jan„ 1962)

. 208.[46] HOT LABORATORY DIVISION, BNL, Instruction sheet for Y® generato r.

[47] GREENE, M .W ., Unpublished m onthly Progr. R ep., Hot Lab. D iv ., BNL (July, 1962).[48] BISHOP, W .N ., Prog. Rep. N ucl. Engg D e p t., BNL, BNL-731 (S -61) (J a n .-A p r .. 1962 ).[49] WEISS, A .J . , Unpublished m onthly Progr. R ep., Hot Lab. D iv .. BNL (Ju ly , 1962 ).[50] HOWARD, F .T . , Cyclotrons and h igh-energy A ccelerators, ORNL-2644 (N o v ., 1958) 311.[51] HILLMAN, М .. "Cross Sections o f 14.5-M eV Neutron Reactions with special Interest in C a4 'F o rm atio n " ,

Nuclear Physics, (in press).


[52] US ARMY QUARTERMASTER CORPS, Radiation Preservation o f Food, PB-151493 ( A u g .. 1957) 4 7 2 . (A vailab le from O ffice o f T ech n ica l Services, US D e p t., o f C o m m ., W ash ., D C .)

[53] ROY. I . e . and HAWTON, I . J . . C an . J. Phys. 39 (1961) 1528-1534.[54] GLICKSTEIN, S .S . and WINTER, R .G ., "N uclear Reactions from Recoil Protons in a Reactor” , Nuclear

Instruments and Methods 9 (1960) 226-228.[55] ROY, J .C . , BRESESTI, M. and HAWTON, J .J . , "On th e Production o f Be in the NRX Reactor by the

B® (p,ot)Be’ , I iT(p ,n )B e’ and Ii6 (d, II)Be1 R eactions", C an . I . Phys. 38 ̂ (1960) 1428-1435.

A useful general reference not spec ifica lly referred to in th e te x t: Special Sources of: Inform ation on Isotopes in Industry, Agriculture, M edicineand Research, Div. of Isot. Development, USAEC ТШ-4563 (3rd Rev.) (Jan ., 1962).

D I S C U S S I O N

G. KIKNADZE: You m e n tio n th e u s e of c i rc u la t in g lo o p s fo r ob ta in ing u l t r a - s h o r t - l iv e d r a d io is o to p e s . Do you h av e any in s ta l la t io n s of th is s o r t in a c tu a l o p e ra tio n a t B ro o k h a v e n ?

L .G . STANG: N o, I sh o u ld p o in t ou t ¡that m y p a p e r w as in te n d e d to be a re v ie w p a p e r , d ea lin g w ith th e w o rk of o th e rs as w e ll a s o u r own w ork a t B ro okhaven . I a lso t r ie d to inc lude so m e id e a s of m y own fo r w o rk w hich I thought m igh t be of fu tu re in te r e s t to th e p a r t ic ip a n ts . T h e se " loops" about w hich you in q u ire r e p r e s e n t one such id ea .

G. KIKNADZE: In co n n e c tio n w ith th is su b je c t o f s p e c ia l m e th o d s o f p ro d u c in g ra d io is o to p e s , I shou ld l ik e to m en tio n th a t s im i la r w ork i s being c a r r ie d out in th e S ov iet U nion on th e ty p e IR T -2 0 0 0 r e a c to r s in T if l i s and R iga . T h e loop fa c ili ty a t T if l is em ploys an alloy of ind ium and g a lliu m w ith a m e ltin g p o in t of 15 .8 °C .T h e f a c ili ty g iv e s n e u tro n - f re e g am m a ra d ia tio n . I shou ld a lso l ik e to r e f e r p a r t ic ip a n ts to o u r a r t i c l e in th e j o u r n a l A tom nay a E n e r g iy a , O c to b e r 1962, p . 342.

C . TA Y LO R : I shou ld l ik e to a s k D r . K ik n ad ze w h e th e r th is f a c i l i ty i s a c tu a lly b e in g u s e d a s a r a d ia t io n s o u rc e .

G. KIKNADZE: Y e s . A s e r i e s of r a d io c h e m ic a l and r a d io - b io lo g ic a l e x p e r im e n ts h a s b e e n c a r r i e d out on i t .

K . FR Ü H A U F : In y o u r o r a l p r e s e n ta t io n you m e n tio n e d m e th o d s f o r th e p ro d u c tio n of B aisim . I w ould l ik e to a s k w h a t w o rk you h a v e done on th is is o to p e , a s w e h av e b e e n w o rk in g on i t to o .

L .G . STANG: M y o r a l p r e s e n ta t io n d e a l t l a r g e ly w ith v a r io u s id e a s w h ich m ig h t b e t r i e d . My r e f e r e n c e r e g a rd in g B a l3? m w as to th e w o rk o f o th e r s . W e h a v e done n o th in g on B a '3’ n> o u r s e lv e s .

P . A LB ER T: Above w hat th e rm a l n eu tro n flux do you th ink it n e c e s s a ry to coo l th e Li6D ta r g e t fo r th e p ro d u c tio n of 14 MeV n e u tro n s?

L .G . STANG: H eat g e n e ra tio n r a t e s fo r L i6D and fo r U235 h av e b ee n c a lc u la te d and c o m p a re d , a s n o te d in r e f e r e n c e 52 to m y p a p e r .

PRODUCTION OF SHORT- LIVED RADIOISOTOPES

P.C . AEBERSOLDUNITED STATES ATOMIC ENERGY COMMISSION, WASH., D .C . AND

A. F. RUPPOAK RIDGE NATIONAL LABORATORY, OAK RIDGE, TENN.,



PRODUCTION OF SHORT-LIVED RADIOISOTOPES. A review is m ade o f th e current lite ra tu re and a bibliography given. Selected references are c ited and com m ent m ade on the general techniques currently em ployed by short-lived radioisotope producers.

A distinction is drawn between the large centrally-local high flux reactors and local reactors for producing short-lived radioisotopes; the com plem entary ro le of the two is pointed out as, for e x am p le , the need for obtaining very high specific activities in special off-site reactors or the need for high-speed transfers and fast processing in local reactors.

The equipm ent and procedures used for irradiating target m aterials to produce short-lived radioisotopes in the three routinely-operated ORNL reactors are described, as well as those for the High Flux Isotope Reactor (HFIR) now under construction a t ORNL, which will have a m axim um flux of 5 x 10** n /cm * s. The use of the HFIR w ill p e rm it production of c erta in short-lived radioisotopes o f unprecedented specific ac tiv ity .

Techniques that have been developed for irradiating samples in various kinds of reactors ranging from the 10“ n /cm * s a ir-co o led , graphite reactor to the high flux (1014 - 1016) w ater-coo led , enriched uranium reactors are described. The requirements for sample irradiations in the various kinds of reactors, such as m a te ria l, m ethod o f sealing , handling, m ethod o f h e a t rem oval, and kinds of sam ple m a te ria ls , a re discussed. Pneum atic transfer tubes are used for irradiations where cooling requirem ents a re not g rea t and fast transfer is desired. Hydraulic tubes are used for irradiation of samples with greater heat generation, although the speed of transfer is not as great as with the pneum atic tubes.

The advantages in using enriched target materials in certain cases are pointed out and several illustrations are given. In some cases, where die target nuclide occurs in low abundance, such as Ca*e in calcium (0.003% ), g rea t advantage can be obtained by using enriched target m ateria ls. This m ay be of im portance to users of lower-flux reactors, since i t could be die only way to get an extra factor of 3-10 in specific activ ity in local irradiations. For exam ple, die very useful radioisotope K*2 could be im proved in specific activ ity from the usual ~10 m c /g in the ordinary low flux (5 x 10u n/cm * s) to about 100 m c /g by using enriched m aterials now av ailab le . This would be most a ttrac tiv e in cases where the expensive ta rge t m a te ria l can be re-used. Good quality short-lived It® (1 2 .5 h) can be m ade in most sm all reactors by irradiating p rac tically stable fission-product I i s , which is re la tive ly cheap and readily availab le .

C hem ical and analy tical problems in producing short-lived isotopes for fast delivery to non-local users are discussed and th e methods and scheduling used a t the ORNL Isotopes D evelopm ent C en ter a re given .

LA PRODUCTION DE RADIOISOTOPES DE COURTE PÉRIODE. Les auteurs passent en revue les récentes publications e t présentent une bibliographie des ouvrages pertinents. Ils c iten t certains ouvrages de référence e t form ulent quelques observations sur les techniques générales actuellem ent appliquées par les fabricants de radioisotopes de courte période.

Ils font une d istinction entre les grands réacteurs à flux de neutrons in tense, insta llés dans des grands cen tres, e t les réacteurs locaux servant à la production de radioisotopes de courte période , e t indiquent le râle com plém entaire que jouent ces deux catégories d'installations: ainsi, on aura recours aux grands réacteurs, m êm e s 'ils sont é loignés, s 'i l s' ag it d 'ob ten ir des radioisotopes d 'une forte a c tiv ité spéc ifique, tandis que l 'o n u tilisera les réacteurs locaux chaque fois qu 'un envoi ou un tra item en t rapide s 'im posera .

Les auteurs décrivent le m atérie l e t les méthodes utilisés pour l'irrad ia tion de m atières cibles aux fins de production de radioisotopes de courte période, dans les trois réacteurs du Laboratoire national d 'O ak Ridge norm alem ent exploités. Ils donnent, d 'autre part, des détails sur le réacteur à flux de neutrons intenses (HFIR), qui y est actuellem ent en construction ( le flux maximum sera de 5*101$ n/cm**s) e t qui perm ettra de fabriquer

31

32 P .C . AEBERSOLD and A .F . RUPP

certa ins radioisotopes de courte période ayan t une ac tiv ité spécifique plus é lev ée que c e lle que l 'o n a pu obtenir jusqu 'ic i.

Le m ém oire expose ensuite les méthodes qui ont é té mises au po in t pour l 'irrad ia tio n d 'échan tillons dans divers types de réacteurs, depuis le réacteur refroidi à l 'a ir e t ralenti au graphite, dont le flux maximum est de 101* n /c m ^ s , jusqu'aux réacteurs à flux intense (10*4 â 10*8) , refroidis à l 'e a u e t a lim entés par de l'u ran ium enrich i. Les auteurs exam inent les problèm es que pose l'irrad ia tion d 'échantillons dans ces divers réacteurs: m atériaux , é tan ch é ité , m anutention, é lim ination de la chaleur e t m atières à em ployer com m e échantillons. Lorsqu'un refroidissem ent poussé n*est pas indispensable e t qu'on a besoin d 'un transfert rapide, on effec tue les irradiations â l 'a id e de tubes pneum atiques. Pour les échantillons dont l 'irrad ia tio n entraihe une plus forte quan tité de chaleur, on a recours à des tubes hydrauliques, b ien que c eu x -c i ne pe rm etten t pas de transfert aussi rap ide que les tubes pneum atiques.

Les auteurs exposent les avantages que présente l 'u tilisa tion , dans certains cas, de m atières cibles en richies e t donnent plusieurs exem ples. Quelquefois, lorsque le nuclé ide c ib le est peu abondant, com m e c 'e s t l e cas de 46C a dans le calc ium (0 , ООЗ^о), i l est très avantageux d 'em ployer des m atières enrichies. C e fa it peu t intéresser no tam m ent les u tilisateurs de réacteurs à fa ib le flux de neutrons, pour lesquels ce serait le seul moyen d 'obtenir, par les irradiations effectuées sur p lace, une activ ité spécifique de 3 à 10 fois plus élevée. Ainsi, grâce à l'em ploi des matières enrichies dont on dispose actuellem ent, l’activité spécifique d e ^ K — radioisotope ex trêm em en t u tile — pourrait ê tre portée d 'environ 10 m c /g , valeur hab itu e llem en t obtenue avec le faible flux de neutrons couramment employé (5 ‘Ю11 n /c m î- s ) , à environ 100 m c/g . C ette méthode serait particu lièrem ent intéressante dans les cas où il est possible d 'u tiliser de nouveau une m atière cib le très coûteuse. Dans la plupart des petits réacteurs, on peut obtenir de l'iode-130 (T ^ = 12,5 h) de bonne qualité en irradiant de l 'io d e-1 2 9 , produit de fission v irtuellem ent s tab le , qui est re la tivem en t bon m arché e t que l 'o n peu t se procurer fac ilem ent.

Les auteurs exam inent enfin les problèmes de chim ie e t d'analyse que pose la production de radioisotopes de courte période destinés â ê tre livrés rapidem ent à des utilisateurs é loignés, ainsi que les méthodes e t les programmes que l'on applique au C entre de production des radioisotopes du Laboratoire national d'Oak Ridge.

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ. Дается обзор современной литературы по общей технологии, обычно используемой предприятиями, производящими короткоживущие радиоизотопы, указывается соответствующая библиография.

Проводится различие между крупными реакторами с интенсивным потоком нейтронов, расположенными на некотором расстоянии от научных центров, и реакторами для производства коротко- жжвущих радиоизотопов, находящимися вблизи потребляющего центра; подчеркивается взаимно дополняющая роль реакторов обоих типов, например потребность в достижении очень высоких удельных активностей на реакторах, расположенных на некотором расстоянии от центров, или же потребность в быстроте доставки и в скорости обработки на реакторах, находящихся вблизи от потребляющего центра.

Описываются оборудование и методы, используемые для облучения материалов мишеней в целях производства короткоживущих радиоизотопов на трех постоянно эксплуатируемых реакторах Окридж- ской национальной лаборатории, а также оборудование и методы, используемые для реактора с интенсивным потоком для производства радиоизотопов (HFIR), который строится в настоящее время в Окриджской национальной лаборатории. Этот реактор должен дать максимальный поток в 5.1018 н/см2•сек. Использование HFIR даст возможность производить некоторые короткоживущие радиоизотопы с еще никогда не достигавшейся удельной активностью.

Описываются технологические методы, которые были выработаны для облучения образцов в реакторах различных типов, начиная с реактора с графитовым замедлителем и воздушным охлаждением, с потоком в 1012н/смг*сек, и кончая реакторами с водяным охлаждением, работающими на обогащенном уране и дающими интенсивный поток нейтронов (1014 — 1015). Обсуждаются требования, предъявляемые к облучению образцов в реакторах различных типов, как,например,в отношении материалов, методов изоляции, способов обращения, способов отвода тепла и видов образцов материалов. Там, где требования охлаждения невелики и желательна быстрота передачи, используется пневмопочта. Для облучения образцов с большим образованием тепла для передачи используется гидравлические трубки, хотя скорость передачи тогда менее значительны, чем при пневмопочте.

Указывается на преимущества использования в некоторых случаях обогащенных материалов для мишеней и приводятся соответствующие примеры. В некоторых случаях, там, где радиоизотопов в мишени очень мало, например Са46 в кальцие (0,003%), большие преимущества представляет ис

PRODUCTION OF SHORT-LIVED RADIOISOTOPES 33

пользование обогащенных материалов мишени. Это может иметь большое значение для экспериментаторов» работающих на реакторах с потоком нейтронов небольшой плотности, так как это может быть единственным способом увеличения в 3 - 10 раз удельной активности при местных облучениях. Например путем использования имеющихся в настоящее время обогащенных материалов можно поднять удельную активность очень полезного радиоизотопа К42 с 10 милликюри/г в обычных потоках небольшой плотности (5»10п н/см2.сек) приблизительно до 100 милликюри/г, что наиболее привлекательно в те'х случаях, когда дорогостоящий материал мишени может быть использован вторично. Коротко- живущий Jl30xopomero качества (12,5 часов) может быть получен в большей части малых реакторов посредством облучения прктически устойчивого продукта деления J 129, который относительно дешев ш который легко достать.

Обсуждаются химические и аналитические проблемы* возникающие при производстве короткоживущих изотопов в целях их быстрой доставки на большие растояния, и указываются методы и установленные сроки, принятые в Центре по выработке радиоизотопов при Окриджской национальной лаборатории.

PRODUCCIÓN DE RADIOISÓTOPOS DE PERIODO CORTO. Los autores exam inan las recientes publicaciones en m ateria de producción de radioisótopos de período corto y presentan una b ib liografía a l respecto. C itan algunas obras de referencia y formulan observaciones sobre las técnicas generales que em plean corrientem ente los productores de radioisótopos de período corto.

Establecen una distinción entre los grandes reactores de flujo elevado, instalados en los centros im portantes, y los reactores locales utilizados para la producción de radioisótopos de período corto; indican e l papel com plem entario que ambos métodos desem peñan; así, se recurrirá a los grandes reacto res, aun cuando se encuentren lejos, cuando se tra ta de obtener radioisótopos de e levada activ idad espec ífica , en tan to que se u tilizarán reactores locales en los casos en que sea necesario un envío o tra tam ien to rápido.

La m em oria describe e l equipo y los procedimientos: em pleados para irradiar m ateria les de blanco y obtener radioisótopos de período corto en los tres reactores que funcionan normalmente en e l Oak Ridge National Laboratory, y los que se em plearán en e l reactor HFIR, de flujo elevado, para la producción de isótopos, que actualm ente se construye en dichos laboratorios, y dará un flujo m áximo de 5 • 1015 n /cm *s. El reactor HFIR perm itirá obtener ciertos radioisótopos de período corto con actividades específicas no alcanzadas hasta e l presente.

Se describen las técnicas desarrolladas para irradiar muestras en diversos tipos de reactores, desde los de 10& n /c m i s , refrigerados por a ire y moderados por g rafito , hasta los reactores de flujo e levado ( lO ^ a 1018 n/cm * s) de uranio enriquecido y refrigerados por agua. La m em oria discute los problemas que plantea la irrad iación de muestras en los diversos tipos de reactores, por e jem p lo , e l m ateria l, e l c ie rre herm ético , la m anipulación, e l m étodo de extracción del calor y las clases de m ateria l que se em plean como muestras. Cuando no resulta indispensable una refrigeración intensa y se desea un transporte rápido se recurre a tubos neum áticos. Para las muestras cuya irradiación entraña e l desprendim iento de una mayor cantidad de calo r, se em plean tubos hidráulicos, aunque la velocidad de transporte que éstos perm iten alcanzar no es tan elevada como en los neum áticas.

La m em oria expoçe las ventajas que en ciertos casos presenta e l em pleo de blancos enriquecidos y da varios ejem plos ilustrativos. En algunos casos, en los que e l núclido blanco es poco abundante como e l 4sCa en e l calc io ( 0 ,0037o) .resulta ventajoso u tilizar como blanco m ateriales enriquecidos. Esto puede ser im portan te para los usuarios de reactores de flujo reducido , porque sería la única m anera de aum entar de 3 a 10 veces ía activ idad específica. Por e jem p lo , em pleando los m ateriales enriquecidos de que ahora se dispone, se podría increm entar la activ idad específica del radioisótopo 42к , que se u tiliza para muchos fines, desde los 10 m c /g que se a lcanzan en los flujos reducidos corrientes (5 • 10u n /c m ís ) hasta unos 100 m c /g . Este m étodo resultaría muy ventajoso en los casos en que se pueda volver a u tiliza r un blanco m uy costoso. En la m ayoría de los reactores pequeños, se puede producir u q de período corto (1 2 ,5 h) irrad iando e l i» l , producto de fisión p rác ticam en te e stab le , que es bastan te bara to y fác il de obtener.

Los autores exam inan por ú ltim o problem as quím icos y analíticos que p lan tea la producción de los radioisótopos de período corto que se han de suministrar rápidamente a usuarios de otras localidades, e indica los métodos y los program as que se ap lican en e l centro de producción de isótopos del Oak Ridge N ational Laboratory.


1. IN TR O D U C TIO N

W hen e n r ic h e d U235 b e c a m e a v a ila b le f o r g e n e r a l r e s e a r c h p u rp o s e s (in 1947), i t r e s u l t e d v e r y q u ic k ly in th e d e v e lo p m e n t o f th e th in A l-U 235 p la te - ty p e of r e a c to r m o d e ra te d and co o led w ith o rd in a ry w a te r . T he f i r s t o f th e s e , th e L IT R (Low In te n s i ty T e s t R e a c to r ) , w a s o r ig in a l ly b u i l t a t O ak R idge a s a h y d rau lic te s t fo r the h ig h e r-p o w ered MTR (M ate ria ls T esting R e a c to r ) , but w as l a t e r c o n v e r te d in to a r e a c to r th a t i s s t i l l in d a ily o p e r a t io n . To m e e t a n ee d fo r im p ro v e d sh ie ld in g te s t s , th e p la te - ty p e r e a c to r w a s a d a p te d by su sp e n d in g a c o r e f ro m a m o v a b le b r id g e c r a n e an d im m e rs in g it in a deep pool of w a te r w hich s e rv e d a s m o d e ra to r , coo lan t, and s h ie ld in g m a te r i a l ; th u s th e "S w im m in g P o o l" r e a c t o r w a s c r e a te d .

T h e s e r e a c t o r s o pened an e n t i r e ly new v i s t a in r e a c to r c o n s tru c t io n and u se , fo r i t w as no lo n g e r n e c e s s a r y to have th e huge and ex p en siv e r e a c to r in s ta lla tio n s , su ch a s th e n a tu ra l-u ra n iu m g ra p h ite o r D 2 0 -m o d e ra te d r e a c to r s , and one cou ld h av e r e a c to r in s ta l la t io n s no m o re e x p e n s iv e and c o m p lic a te d th an th e p a r t ic le a c c e le ra tin g m a c h in e s , w ith w hich m any u n iv e r s i t i e s , in d u s t r ia l la b o ra to r ie s , and r e s e a r c h fo u n d a tio n s had b ee n f a m i l i a r f o r y e a r s .

D u rin g th e fo llow ing y e a r s , p a r t i c u la r ly a f te r e n r ic h e d u ra n iu m w as m a d e a v a i la b le by th e U n ite d S ta te s f o r u s e by o th e r c o u n t r i e s (in 1954), th e in s ta l la t io n of s m a ll e n r ic h e d -u ra n iu m r e a c to r s p ro ce ed ed rap id ly u n til in 1962 th e r e w e re m o re than 150 r e a c to r s b u ilt o r p lanned in 24 c o u n tr ie s . T he r e s e a r c h p ro g ra m m e s th a t have grow n up a round th e se r e a c to r s c e n tre on the u se of the n eu tro n s in d iffra c tio n and ab so rp tio n ex p e rim en ts , sh ie ld ing te s ts , r e a c to r c o n tro l ex p e rim en ts , tra in in g in ex p e rim en ta l n u c lea r physics, an d — of m o st u n iv e rsa l in te re s t — the production of rad io iso to p es .

2 . P U B L IC A T IO N S ON S H O R T -L IV E D R A D IO ISO T O PE PR O D U C TIO N

In go ing th ro u g h th e l i t e r a tu r e , we n o te d th a t r e la t iv e ly l i t t le h a s b ee n pub lished sp e c if ic a lly on the p roduction of s h o r t- liv e d rad io iso to p es , although c o m m e n t i s in c lu d e d in a n u m b e r of p u b lic a t io n s L 1 -15J. S e v e ra l o f th e s e d is c u s s s h o r t - l iv e d r a d io is o to p e s in so m e d e ta i l .

KING e t a l . L14J w orked w ith the f i r s t lo w e r-p o w e r r e a c to r devoted e x c lu s iv e ly to m e d ic a l r e s e a r c h , a lo w -p o w er (5-W A G N -201-M ) r e a c to r th a t h a d a f lu x o f o n ly 2 .5 X 1 08n /cm 2 s . N e v e r th e le s s , m i l l i c u r ie a m o u n ts of r a d io is o to p e s (which th e y l is t) cou ld be p ro d u ce d by s a tu ra tio n ir ra d ia t io n , a lth o u g h th e y p o in t ou t th a t th is i s p r a c t ic a l on ly fo r r e la t iv e ly s h o r t h a lf- l iv e s o f l e s s th a n abou t 12 h . E x te n d ed 2 4 -h o p e ra tio n i s e x p e n s iv e , bu t a few d a y s of c o n tin u o u s o p e ra tio n c a n e a s i ly be a r r a n g e d a t th e s m a l l l a b o r a to r y ; th is we th in k i s an im p o r ta n t p o in t in re c o m m e n d in g p ro d u c tio n of s h o r t - h a l f - l i f e r a d io is o to p e s fo r su c h r e a c to r s . R e fe re n c e i s m ad e to th e f a s t c h e m is try a s so c ia te d w ith s h o r t- liv e d rad io iso to p es and the p o ss ib ilitie s o f u s in g S z i la r d -C h a lm e r s r e a c t io n s fo r e n r ic h m e n t . M en tion i s m a d e of m e d ic a l a p p lic a tio n s , p a r t i c u la r ly C u64 f o r b r a in tu m o u r w o rk , M n56 fo r b lood vo lum e s tu d ie s , and N a24 , K 42, and C l38 in blood s e ru m s tu d ie s . The


a u th o rs reco m m en d the u se of s h o r t- liv e d ra d io iso to p e s in d iag n o stic s tu d ie s on h u m an p a t ie n ts , on th e b a s i s of lo w e r to ta l r a d ia t io n d o sa g e to t i s s u e s .

K N O L L 111, w h ile n o t d is c u s s in g s h o r t - h a l f - l i f e r a d io i s o to p e s s p e c if ic a lly , re v ie w s som e of th e techno logy of rad io iso to p e p ro d u c tio n in E a s t G erm an y .

HAUCK [9 ] re v ie w s th e u se of sm a ll r e a c to r s , em p h asiz in g th e ir p a r t ic u la r v a lu e fo r p ro d u c tio n of s h o r t-h a lf - l i f e ra d io iso to p e s . A r a th e r co m p le te ta b le of ra d io iso to p e s With h a lf - liv e s f ro m 5 m in to 100 d i s given, and p a r t i c u la r m e n tio n i s m a d e of th e n e w e r n e u tro n b u r s t r e a c to r s , su c h a s TR IG A , w h ich g iv e p u ls e d n e u tro n f lu x e s a s h ig h a s 4 X 1 0 1B n /c m 2 s f o r s h o r t p e r io d s . S uch r e a c to r s a r e o f e s p e c ia l i n t e r e s t f o r p ro d u c in g v e r y sh o r t- l iv e d ra d io iso to p e s . H auck c i te s th e ad v a n ta g es of s h o r t- l iv e d r a d io is o to p e s ; he s t a te s th a t r e la t iv e ly l a r g e a m o u n ts o f r a d io a c t iv i ty c a n b e qu ick ly p ro d u ced and th a t i t qu ick ly d is a p p e a rs a f te r the e x p e rim e n t i s o ver, th u s obv ia ting th e w a s te -d isp o sa l p ro b lem .

T e c h n iq u e s f o r f a s t r a d io c h e m is t r y a r e d is c u s s e d by М Е Щ К Е L16J, w ith n u m e ro u s re fe re n c e s , includ ing the im p o rta n t re p o r t of the US N ational R e s e a rc h C ounc il S u b co m m ittee on R a d io c h e m is try [1 7 J . A lthough m o s t of th e f a s t c h e m ic a l s e p a r a t io n s w e re d e s ig n e d fo r a c tiv a tio n a n a ly s i s w ork , m any of th e m a r e re a d ily adap tab le fo r s e p a ra tio n s and p u rifica tio n of ra d io iso to p e s fo r r e s e a r c h .

A s p e c ia l r e p o r t fo r th e US A tom ic E n e rg y C o m m iss io n by SHARP and SCHM ITT [ 18j g iv e s a th o rough d is c u ss io n of the S z ila rd -C h a lm e rs p ro c e s s f o r p ro d u c in g s h o r t - l iv e d r a d io is o to p e s o f h ig h s p e c if ic a c t iv i ty in s m a l l r e a c t o r s . M e th o d s a r e g iv e n fo r 3 8 -m in C l38 , 2 5 -m in 1 128 , 2 .6 -h M n 56,4 .6 -h B r 80, 1 2 -h C u 6 4 , 1 4 - h Z n 6 9 m ( 27-h A s™ , 2 7 - h S n i2 i , and 36-h Br82. I r r a d ia t io n s w ere m ade in a lO -k W TRIGA r e a c to r a t a flux of 6 X 1 0 % /c m 2 s .

V a r io u s t a r g e t m a te r i a l s w e re u se d fo r S z i la r d -C h a lm e r s r e a c t io n s , su c h a s ch lo ro b e n z e n e fo r C l38, КМПО4 fo r M n56 j and p h th a lo cy a n in e s fo r C u 64 an d Z n B3m . F a i r y ie ld s an d good e n r ic h m e n ts by f a c to r s of te n s to s e v e r a l th o u san d w e re ob ta in ed . E x p e r im e n ts to p ro d u ce C l38 by ca p tu r in g r e c o i l s f ro m th in p la s t ic f i lm s c o n ta in in g c h lo r in e w e re a l s o s u c c e s s f u l .

3. TH E CO M PLEM ENTA RY ROLES O F LARGE AND SM ALL REACTORS

In th is S e m in a r , a t te n t io n i s d i r e c te d s p e c if ic a l ly to w a rd r e a c t o r - p ro d u c e d s h o r t - l iv e d ra d io is o to p e s th a t a r e d efined a s th o se fo r w hich th e h a lf- l iv e s a r e re c k o n e d in m in u te s o r h o u rs , ex ten d in g up to th r e e d ay s . W hile a g r e a t d e a l of v e r y good and u se fu l w o rk h a s b een done w ith m a te r ia l w ith h a l f - l iv e s o f m in u te s o r ev e n se c o n d s , we c o n s id e r th a t one h o u r i s abou t th e s h o r te s t h a l f - l i f e d e s i r a b le f o r p r a c t i c a l la b o r a to r y w o rk , ex c lu d in g , o f c o u r s e , a c tiv a tio n a n a ly s is . In T ab le I, we have l is te d in o r d e r m o s t o f th e r a d io is o to p e s p ro d u c e d by o rd in a ry n e u tro n -g a m m a re a c t io n and c a te g o r iz e d by h a lf - l iv e s betw een 1 h and 3 d. The n a tu ra l iso tope abundances of th e t a r g e t a to m s a r e n o te d , a s w e ll a s n e u tro n a b s o rp tio n c r o s s - s e c t i o n s and th e sp e c if ic a c t iv i t ie s p ro d u ced a t h igh and low n e u tro n f lu x e s . F u r th e r r e f e r e n c e w ill be m ade to th e T ab le l a te r in th is d isc u ss io n .

36

TABLE I

S H O R T -L IV E D ISOTOPES, T1/2= 1.5 to 65 h

P. С . AEBERSOLD and A. F. RUPP

zProductisotope

V(b)

Target atom, natural

abundance (%)

Activationcross-section

(b)

Specific activity (m c/g)

Ф - 1011n /c m 2s ф - 10I5n/cm 2 s

56 Ba139 1.42 71.66 0.5 4.27 42 70060 Nd149 . 1.8 5.72 3.7 2.38 23 80018 Ar4l 1.82 99.6 0.53 2.13 2130070 Yb*77 2.0 12.73 5.5 66.3 . 663 00066 Dyl65 2.3 28.18 1000a) 2790 25100 00028 Ni65 2.56 1.16 2.6 0.82 820014 Si31 2.62 3.05 0.11 0.195 195025 Mn56 2.58 100 13.4 390 3 900 00055 Csl34 2.9 100 3 36.7 367 00071 Lu176 3.7 97.4 35b) 318 2 940 00030 Zn71 4 0.61736 85 ГП 4.4 56.9 0.1 1.09 10 90044 Ru® 4.5 18.56 0.7 2.1 2110035 Br8» 4.6 49.48 2.9 29.2 292 00046 Pdu l 5.5 11.81 0.05 0.091 91068 Er171 7.5 14.88 9 13.0 13000058 C e137 8.7 0.193 6.3 0.14 141063 Euiæ 9.3 47.77 1400 7150 59 500 00032 G e77 12 7.67 0.08 0.137 137019 К42 12.5 6.91 1.1 3.17 3170053 jlSO 12.6 50.0C) 24<i) 152 1520 00029 Cu64 12.8 69.1 4.3 75.5 755 00046 pd109 13.6 26.71 10 41 410 00076 Osisi 14 26.4 40 91.2 912 00030 Zn«9 14 18.54 0.1 0.462 462031 Ga72 14.1 34.8 4 37.0 370 00011 Na24 15 100 0.54 38.3 383 000

. 75 Re 188 17 62.93 69 376 3 760 00040 Z r97 17 2.80 ' 0.1 0.05 50064 Gd159 18 24.87 4 10.3 103 00077 Irl»4 19 62.7 130 692 6 920 00059 pr 14 2 19.3 100 10 115 1150 00074 W187 24 28.4 34 85.3 85300080 Hg197m2 25 0.15 3000 36.4 20000033 As76 27 100 5.4 117 1170 00035 Br82 36 49.48 3.1 31.2 312 00056 Ba133 39 0.097 4.1 0.047 47257 La140 40 99.9 8 93.2 9320062 Smls3 47 26 140 394 3 500 00048 Cd« 3 53 29 1.1 4.64 4640054 X e « 3 55.2 26.89 0.2 0.67 6 70039 y90 64 100 1.3 23.7 237 00079 Aul98 64.8 100 96e) 795 797 000

a)Dy!65 cross-section, 5000 b;

b)Smlre cross-section, 4000 b;c)Radioactive fission product, ha lf-life l x l 0 7yr; isotopic abundance from ORNL data, balance is I127;d)l130 cross-section, 18 b;e)Aul98 cross-section, 26 000 b.


T h e r e a c t o r s o p e ra t in g a t th e l a r g e r e s e a r c h an d r a d io is o to p e p r o d u c tio n c e n t r e s su c h a s O R N L h a v e q u ite h ig h f lu x e s , r a n g in g f r o m 1011 to . 5X1015 n /c m 2 s — o r d e r s of m ag n itu d e h ig h e r th a n th e f lu x es in th e s m a ll r e s e a r c h r e a c to r s , w h ich a r e th e p r in c ip a l s u b je c t o f th i s S e m in a r —an d m igh t th e re fo r e no t a p p e a r p e r tin e n t to th e d isc u ss io n . H ow ever, we b e liev e th a t th e tw o k inds of in s ta l la t io n s have som ew hat c o m p le m e n ta ry ro le s , and a ls o th a t th e e x p e r ie n c e w ith th e h ig h e r- f lu x r e a c to r s ca n in so m e w ays be in s t ru c t iv e to th o s e u s in g s m a ll r e s e a r c h r e a c to r s .

T a b le Ы l i s t s s h o r t - l iv e d r a d io is o to p e s ro u tin e ly p ro d u c e d and d i s t r i b u te d b y O R N L . T h e i r r a d i a t i o n s a r e m a d e , th e t a r g e t m a t e r i a l i s p r o c e s s e d , a n a ly s e d , p a c k a g e d , an d sh ip p e d to u s e r s a s f a r a s 3000 m i l e s aw ay, a r r iv in g w ith a sp e c if ic a c tiv i ty often s t i l l h ig h e r th a n th a t w hich can be p ro d u c e d in a lo c a l r e a c to r . It w ill be n o te d th a t T a b le II in c lu d e s m o s t of th e ra d io is o to p e s in T ab le I w ith h a l f - l iv e s lo n g e r th a n 12 h; th e s e have b een found to be qu ite p r a c t ic a l to hand le th is w ay. T h is is p o ss ib le b ecau se th e n e u tro n f lu x (and r e s u l t in g sp e c if ic a c tiv ity ) i s th r e e to fo u r th o u sa n d t im e s a s h ig h in th e h ig h -p o w e r r e a c to r s an d th e r e f o r e th e a c t iv i ty co u ld d e c a y aw ay fo r abou t 12 h a l f - l iv e s b e fo re i t r e a c h e d th e le v e l p ro d u ce d in th e lo w -flu x r e a c to r ; w ith a 12-h h a lf- life , th is would allow a s m uch a s 5 d. W ith d i r e c t a i r t r a n s p o r t and good hand ling , . one ca n sh ip m a te r ia ls a lm o s t a ro u n d th e w o rld in 24 h.

T h is w ou ld s u g g e s t th a t one o f th e m a in a r e a s f o r r a d io is o to p e p r o d u c tio n f o r s m a l l lo c a l r e s e a r c h r e a c t o r s i s in th e h a l f - l i f e r e g io n f ro m m in u te s to abou t 10 h . Of c o u rs e m any s m a ll r e s e a r c h r e a c to r s a r e lo ca ted in a r e a s n o t s e rv e d by l a r g e - s c a l e ra d io iso to p e p r o d u c e rs , and th e lo w e r c o s t an d c o n v e n ie n c e of lo c a l p ro d u c tio n a r e c o n tro l l in g f a c to r s . N e v e r th e le s s , th e a v a ila b il i ty o f a n a ly se d , h ig h - s p e c if ic - a c t iv i ty p ro d u c ts f ro m th e l a r g e r a d io is o to p e - p ro d u c in g s i t e s w ill no dou b t in f lu e n c e f u tu re d e c i s io n s on w h e th e r to b u ild and o p e r a te lo w e r -p o w e r r e a c t o r s f o r r a d io i s o to p e s .

It i s c le a r th a t the p o sitio n of the sm a ll r e a c to r o p e ra to r w ill be enhanced by s p e c ia l iz a tio n in th e p ro d u c tio n and u se of ra d io is o to p e s w ith h a l f - l iv e s o f m in u te s to a few h o u rs .

4 . REACTOR PRODUCTION OF SHORT-LIVED RADIOISOTOPES AT ORNL

R a th e r e f f ic ie n t te c h n iq u e s a r e u s e d f o r p ro d u c tio n , a n a ly s i s , an d sh ipp ing of the f a ir ly s h o r t- liv e d ra d io iso to p e s a t the ORNL Iso to p es C e n te r. T he m a in p ro d u c tio n r e a c to r s a r e th e ORR w ith a f lux of 1.5 X 1014 n /c m 2 s and n u c le a r h e a tin g of 6 W /g in th e h y d ra u lic tube zone, and th e L IT R w ith a f lu x of lX 1 0 13n /c m 2 s an d n u c le a r h e a tin g of 0 .5 W /g in th e p n e u m a tic tu b e zone. N ote th a t w ith th e d if fe re n c e in flux by a fa c to r of 10, we u se two d i f f e r e n t d e v ic e s : th e a i r - o p e r a t e d - a n d - c o o le d p n e u m a tic tu b e a t lo w e r p o w e r an d th e w a te r -o p e ra te d - a n d - c o o le d h y d ra u lic tu b e a t h ig h e r p o w er. T h is i s p r im a r i l y b e c a u s e m o r e c o o lin g i s r e q u i r e d a t th e h ig h f lu x th a n c a n be e a s i ly done w ith a i r . I t i s q u ite f e a s ib le o f c o u r s e to u s e h y d ra u lic tu b e s f o r th e lo w e r - f lu x r e a c to r s , and th e y do h av e th e ad v a n ta g e of e a s y lo a d in g and u n lo ad in g u n d e r w a te r in th e p o o l a s s o c ia te d w ith th e r e a c to r .

TABLE II

SHORT-LIVED ISOTOPES ROUTINELY PRODUCED AT ORNL

38 P .C . AEBERSOLD and A. F. RUPP

Isotope H alf-life Target m aterial Processingmethod Product form Method of

analysis

Sb122 67 h Sb m etal Dissolution SbClg + SbOCl IC, SC

As76 26.6 h As¿03 Distillation HAsQj in HCl sol.

IC, SC

As77 38.8 h GeCfe Distillation HAs02 in HCl sol.

PC

Ba131 11.6 d BaC03 (BafNOg^) Ion Exchange BaCIz yS

Bi210 5.02 d Bi m etal Dissolution Bi(NOg) 3 PC

Br82 35.87 h KBr Ion Exchange KBr in H20 sol. IC, SC

Cdlls 53 h Cd m etal Dissolution Cd (NOg), PC

C a47 4.7 d Ca46 enriched Dissolution C aCl2 IC, SC

La140 40 h Dissolution LaCl, IC, SC

Hgl97m2'197 24 h; 65 h HgO Dissolution H gfN O ^ IC, SC

Mo98 66 h Moq, Dissolution Ammonium molyb- date in NH,OH

PC

Pd109 13.6 h Pd m etal Dissolution PdCl2 PC

K12 12.47 h k 2c o 3 Dissolution KC1 IC, SC

Pt‘42 19.3 h Pt2°3 Ion Exchange PrClg PC

Re186 91 h Re m etal Dissolution HRe04 in HN03 sol.

yS

Ru97 69.6 h Distillation RuCl, yS

Sm153 47 h Sm20 3 Dissolution Sm Cl3 IC, SC

А Г 7.5 Pd m etal Ion Exchange AgN03 PC

Na“ 15.0 h Na2C 03 Dissolution NaCi IC, SC

Cu64 12.8 h Cu m etal Dissolution Cu(N 03)2 IC, SC

Ga72 14.2 h Ga2O s Dissolution GaCl3 IC, SC

Au198 65 h Au m etal Dissolution AuClj- Mixed HC1 + HN03 sol.

1C, SC

Au199 75.6 h Pt Extraction AUCI3 IC. SC

¡130 12,5 h I129 fission Distillation Nal basic Na sulphite sol.

SC, IC

Ir191 19 h Ir m etal Fusion N ^IrC l, PC

WOT 24.0 h w o , Fusion W in KOH sol. IC, SC

y90 64.2 h Fission U Solvent ext. YC13 extraction PC

Notation: IC - ion cham ber SC - scintillation counterPC - proportional counting yS - gam m a scanning


T h e re a r e a ls o p n e u m a tic tu b e s in th e ORR th a t a r e u se d w ith q u ite s m a ll s a m p le s in som ew hat lo w er flux zones. V ery ra p id t r a n s p o r t (50 to 2 5 0 f t/s ) i s p o s s ib le w ith th e pn eu m atic tu b e s , and th e s e a r e u se d to t r a n s p o r t s m a ll s a m p le s d i r e c t ly to c o u n te r s fo r m e a s u r e m e n t o f v e r y s h o r t - l iv e d r a d io is o to p e s fo r r e s e a r c h and a c tiv a tio n a n a ly s is . T he sp e ed of s a m p le m o v e m en t in th e h y d rau lic tu b e s i s c o n s id e rab ly le s s — about 4 f t / s . The c a r r i e r s in th e tu b e s a r e r e f e r r e d to a s " r a b b i ts " ; th e y m a y be m ad e of p la s t ic fo r lo w -p o w e r i r r a d ia t io n s (p o ly e th y len e and T eflo n have b ee n u se d ), b u t i t i s a d v is a b le to u s e 97% M g-3% A l a l lo y . S a m p le s’ a r e u s u a l ly p a c k a g e d in p la s tic , m e ta l fo il, o r p u re q u a r tz and c a r r ie d w ith in th e ra b b its . The LITR p n e u m a tic tu b e r a b b i t s a r e 5 /8 in d ia m . X 2 - 3 /8 in long . T h e to ta l r a b b i t s iz e and w eight i s kep t to a m in im u m in th e pn eu m atic tu b e s to allow b e t te r m ovem en t. The g e n e ra l d es ig n of th e pneum atic tube i s shown sc h em a tic a lly in F ig . 1. Im p o r ta n t p o in ts a r e to k ee p a l l b e n d s sm o o th and s tr e a m lin e d , u se m a te r ia l s w hose s u r fa c e s do no t g a l l in c o n tac t, a llow ad eq u a te c l e a r a n c e s , an d p ro v id e f o r e x h a u s t o f p o s s ib ly c o n ta m in a te d a i r in c a s e th e

F ig .l

UTR Pneum atic Tube System

40 P .C . AEBERSOLD and A. F. RUPP

c a p su le i s ru p tu re d in th e r e a c to r . The ra b b its m ay be u se d aga in and again if th e y have n o t b een i r re v o c a b ly co n tam in a te d by d i r e c t c o n tac t w ith ta rg e t m a te r i a l s . S a m p le s a r e p u t in to an d ta k e n o u t o f th e r e a c t o r th ro u g h a 2 4 -p o s itio n m a g a z in e b u ilt w ith c o n c e n tr ic r in g s w ith 12 h o le s ea ch . F ro m th e sh ie ld e d m a g a z in e , th e i r r a d ia te d s a m p le s ca n be re a d ily d ro p p ed in to a sh ie ld ed c a r r i e r . D ry c o m p re sse d n itro g e n i s u sed fo r pushing the rab b its in to and out of the r e a c to r . C leaned, d r ie d a i r i s a lso u sed when it is n e c e s s a r y to m a in ta in flow f o r co o lin g p u rp o s e s o v e r lo n g e r p e r io d s of i r r a d i a tio n a t th e h ig h e r f lu x e s . E le c tr ic a lly -o p e ra te d so leno id v a lv e s c o n tro l the g a s p r e s s u r e s , an d a u to m a tic c o n t ro ls p e r m i t p r e c i s e t im in g o f s a m p le i r r a d ia t io n s . T he m ag az in e i s sh ie ld e d w ith 5 -3 /4 in of lead , and the r a d ia t io n re a d in g s a t th e s u r fa c e n e v e r ex c ee d 1 m r /h . A u se fu l d ev ice added to th is eq u ip m en t w as a s e n s it iv e m ic ro p h o n e and sound a m p lif ie r a tta c h e d to th e tu b e s , w h ich e n a b le d th e o p e r a to r to h e a r a d is t in c t " c l ic k " w hen th e r a b b i t r e a c h e d i t s p r o p e r p la c e in th e r e a c to r .

T he h y d ra u lic tu b e f a c il i ty u se d in th e ORR is sk e tch e d in F ig . 2. N ote th a t a d e lay ta n k fo r N 16 decay i s p rov ided , and co n tam in ated hy d rau lic tube w a te r c a n b e d iv e r te d to a f i l t e r in g an d io n e x c h a n g e s y s te m in c a s e o f c a p s u le r u p tu re . S u itab le m o n ito r in g d e v ic e s to d e te c t ru p tu re c a n be in c o rp o ra te d in to th e e x h a u s t a i r o r w a te r s t r e a m s u se d fo r tr a n s p o r tin g and coo ling th e s a m p le s .

In o r d e r to e ffe c tiv e ly u ti l iz e th e sp a c e in th e v e ry v a lu ab le h ig h -flu x zo n e (1.5 X 1014n /c m 2 s , 6 W /g h e a tin g ) , a b u n d le o f 4 h y d ra u lic tu b e s i s p ro v id e d . T h re e a r e 1 in d ia m . , an d one i s 1 - 1 /2 in d ia m . ; th e y h a v e a co m m o n r e tu r n l in e 1 in d ia m . T h is s y s te m i s c o m p lic a te d , in th a t i t i s d if f ic u lt to o p e r a te one o f th e tu b e s w ith o u t d is tu rb in g th e s a m p le s in th e o th e r tu b e s . A n o th e r f iv e - tu b e bund le w as in s ta l le d , w ith e a c h tu b e hav ing i t s ow n w a te r r e tu r n l in e ; t h i s w a s found to b e a g r e a t im p r o v e m e n t . In th e o p e ra tio n of h y d ra u lic tu b e s , s a m p le s a r e p la ce d in u n d e rw a te r sa m p le boxes (in the r e a c to r pool) and the ra b b its a r e pushed into the r e a c to r , using th e poo l w a te r c irc u la t in g pum p p r e s s u r e ; o p e ra tin g co n d itio n s a r e a w a te r flow r a te of a p p ro x im a te ly 10 g a l /m in a t 25 p s i. A s p rev io u s ly noted , o p e r a tio n i s sh ifted to the r e a c to r w a te r sy s te m in c a se of a cap su le ru p tu re , so th a t th e co n tam in a te d w a te r can be p ro p e r ly c lean ed and con tained in a c lo sed s y s te m . In rem o v in g a sa m p le , w a te r flow i s r e v e r s e d and th e sa m p le r e tu r n s to th e u n d e rw a te r s ta t io n (u n d er ~9 ft of w a te r ) , w h e re th e sa m p le i s r e t r ie v e d and t r a n s f e r r e d to a sh ie ld e d c a r r i e r u n d e rw a te r . F a c i l i t i e s a r e a ls o p ro v id e d to t r a n s f e r th e r a b b it to a h e a v ily -s h ie ld e d m a n ip u la to r c e l l th a t i s p la c e d o v e r one end of th e r e a c to r poo l. T he r e a c to r s e c tio n of the h y d ra u lic - tu b e d ev ic e i s m ad e of a lu m in iu m and th e r e a c to r pool p a r t s a r e of s ta in le s s s te e l . M icrophones and a m p lif ie r s a r e a lso u se d on th e se tu b e s to ch e ck on ra b b it p o sitio n in g .

W hile th e O RN L a i r - c o o le d g ra p h ite r e a c to r i s n o t u se d a g r e a t d e a l fo r ra d io is o to p e p ro d u c tio n , s in c e th e h ig h e r - f lu x r e a c to r s a r e a v a ila b le , a v e ry s im p le m ethod u se d fo r i r r a d ia t io n s a t lo w er flux (~ 8X 10u n /c m 2 s) in th is r e a c to r m ay be of in te r e s t . A t su c h f lu x e s , e la b o ra te eq u ip m en t is no t n e c e s s a r y fo r good r e s u l t s , and o rg a n ic m a te r i a l s su c h a s lin e n c o rd and p o ly e th y le n e c o n ta in e rs ca n be u se d f o r s h o r t i r r a d ia t io n s . E q u ip m en t fo r th e " s a m p le on a s t r in g " m e th o d w a s in s t a l l e d in one o f th e v e r t i c a l

. REMOVABLE COVER

HYDRAULIC ,RABBIT ,

ALTERNATE STATION INSIDE HOT CELL

RAB8IT TU0E(No.3) RABBIT TUBE (No.A) RABBIT TUBE (No. 2) RABBIT TUBE (No-1)

LATTICE ELEMENT CONTAINING HYDRAULIC TUBES

Fig. 2

ORR Hydraulic Tube System

PROD

UCTIO

N

OF SH

ORT-LIV

ED

RA

DIO

ISOTO

PES

42 P. C . AEBERSOLD and A. F. RUPP

ho le s in the g rap h ite r e a c to r (flux 8 X 10n n /c m 2 s) , w here the n u c le a r heating i s on ly 3 m W /g an d i s th e r e f o r e n o t a p ro b le m . T h e o r ig in a l in s ta l l a t io n w a s a w a te r - c o o le d tu b e , b u t th i s w a s r e p la c e d w ith a i r c o o lin g (F ig . 3),


w hich s im p lif ie d o p e ra tio n and m a in te n a n c e . A tm o sp h e ric a i r is pu lled o v er th e s a m p le s an d th ro u g h th e b o tto m of th e tu b e b y th e n e g a tiv e p r e s s u r e m a in ta in ed by th e r e a c to r cooling sy s te m . On top of the tube i s an a sse m b ly com p o sed of a s lid in g d o o r fo r ra d ia tio n sh ie ld in g and a s ix -p la c e m ag az in e f o r re c e iv in g th e i r r a d ia te d s a m p le s . By ro ta t in g the m ag az in e , any one of the s to ra g e p o sitio n s can be a ligned fo r the in se r t io n o r rem o v a l of sa m p le s ; h ow ever, th e re is no p ro v is io n fo r loading a sam p le d ire c tly fro m the m a g az in e to a s h ie ld e d c a r r i e r . It sh o u ld b e n o te d th a t th e ro ta t in g - m a g a z in e p r in c ip le h a s b ee n su c c e s s fu l ly u se d on m any k inds of i r r a d ia t io n f a c i l i t i e s on r e a c t o r s th ro u g h o u t th e w o rld . D if fe re n t k in d s o f s a m p le s a r e h a n d led in v a r io u s w ays, depending on the d u ra tio n of the ex p o su re . F o r ir ra d ia tio n s up to 16 h, s m a l l p o ly e th y le n e b o tt le s t ie d to a w axed lin e n c o r d a r e s u s pended in th e h o le . If th e i r r a d ia t io n tim e i s on ly a few m in u te s to p e rh a p s an h o u r , th e c o rd i s t ie d d i r e c t ly to th e b o ttle ; o th e rw is e , i t i s t ie d to an a lu m in iu m w ire b a le f itte d onto the bo ttle , so th a t the sam p le can be e a s ily r e t r i e v e d w ith a ho o k if th e c o rd sh o u ld f a i l . In lo n g e r i r r a d i a t i o n s , th e p o ly e th y le n e b o ttle i s h e ld in a p u re a lu m in iu m ca n f it te d w ith a b a le . T he s a m p le s m ay be s ta c k e d in th e ho le and in s e r te d and r e t r ie v e d w ith a hook. W hen a lu m in iu m c a n s a r e u se d , i t i s n e c e s s a r y to a llo w a d e c a y t im e of ab o u t a n h o u r b e fo re th e s a m p le c a n b e re m o v e d f ro m th e s h ie ld .

T h e re i s u n d e r c o n s tru c tio n a t p r e s e n t a t ORNL a r e a c to r (HFIR , th e H igh F lu x Iso to p e R e a c to r ) th a t w ill a c h ie v e th e e x t r a o r d in a r y f lu x of 5X 10I5n /c m ? s and th e r e f o r e s e e m s ev en m o re re m o te f ro m th e s m a l l r e s e a r c h r e a c t o r s th a t a r e th e s u b je c t o f th i s S e m in a r . N e v e r th e le s s , th is r e a c t o r w ill e n a b le su c h a lo n g s te p f o rw a r d in th e p ro d u c tio n o f r a d i o iso to p e s , p a r t ic u la r ly s h o r t- l iv e d n u clid es , th a t it se e m s w orthy of m ention. U se of th is r e a c to r w ill a llow th e p ro d u c tio n of s h o r t- l iv e d ra d io iso to p e s of u n p re c e d e n te d s p e c if ic a c t iv i t ie s , p a r t i c u la r ly f o r th o s e n u c l id e s th a t ca n b e m a d e on ly by th e n e u t ro n -g a m m a r e a c t io n ; in th i s c o n n e c tio n , p le a s e r e f e r to T ab le I, w h e re th e c a lc u la te d v a lu e s a t 10 i5 n /c m 2 s a r e g iven . We no te in p a s s in g th a t a t th e s e e x tre m e ly h igh f lu x es th e se c o n d a ry b u rn u p of p ro d u c t n u c lid e s b ec o m e s im p o rta n t in a few c a s e s w h ere the c ro s s - s e c t io n of th e ra d io iso to p e p ro d u ce d i s f a ir ly la rg e — fo r ex am p le , s e v e r a l h undred b a rn s .

I r r a d ia t io n in the H FIR w ill p re s e n t som e fo rm id ab le p ro b le m s. P r im a r i ly d es ig n ed fo r ir ra d ia t io n of tra n s -p lu to n iu m e lem e n ts , it is com posed of an a n n u la r th in -p la te fu e l e le m e n t of u n u su a l d es ig n to p e rm it th e en o rm o u s h ea t t r a n s f e r of 1 000 000 B T U /ft2h; it is m o d era ted and cooled w ith o rd in a ry w a te r . In s id e th e a n n u la r fu e l p ie c e i s an " i s la n d " o f w a te r in w h ich th e n e u tro n f lu x r e a c h e s a m a x im u m . In th i s is la n d , th e s a m p le s to be i r r a d ia te d fo r p ro d u c tio n of. t r a n s c u r iu m is o to p e s w ill be p la c e d . T he n u c le a r h e a tin g in o r d in a r y m a te r i a l s (n o n -f is s io n a b le ) w ill be a s h ig h a s 50 W /g . U nder th e s e co n d itio n s , h e a t re m o v a l f ro m th e ta rg e t , and t a rg e t m a te r ia l s ta b il i ty a r e p a ra m o u n t.

T h e r e a c to r i s c o o le d by o r d in a r y w a te r a t an o p e ra tin g p r e s s u r e of 900 p s i, so th e in tro d u c tio n of a h y d ra u lic tu b e fo r ra d io iso to p e p ro d u c tio n w ill be one of th e m o s t fo rm id a b le e n g in e e rin g p ro b le m s y e t fac ed in r a d io is o to p e p ro d u c tio n . T h e d e s ig n c a l l s f o r h e a v ie r m a te r i a l s th a n u s u a l to w ith s tan d p r e s s u r e , d e v ic e s to a llow p a r t i a l re m o v a l of tube s e c tio n s when


th e ta n k i s opened d u r in g re fu e ll in g , an d m a x im u m p re c a u tio n s to p re v e n t lo s s o f co o lin g a t an y t im e . T a r g e t m a te r i a l s m u s t be s e le c te d w ith g r e a t c a r e to e n s u re s ta b i l i ty , and th e u s e of u l t r a - p u r e m a te r i a l s i s e s s e n t i a l b e c a u se lo n g e r- l iv e d ra d io a c tiv e im p u r i t ie s w ill be a c c e n tu a te d in sa m p le s th a t have re a c h e d s a tu ra tio n and th en a llow ed to decay .

A s a r e s u l t of th is w ork , d a ta on ta rg e t m a te r ia ls , i r ra d ia t io n m ethods, an d ra d io is o to p e n e u tro n c r o s s - s e c t i o n s w ill b ec o m e a v a ila b le th a t shou ld b e of v a lu e to r a d io is o to p e p r o d u c e r s , in c lu d in g th o s e u s in g th e s m a l l e r r e s e a r c h r e a c t o r s .

5. F A S T HANDLING, PR O C ESSIN G , AND A N ALY SIS-IN T H EPR O D U C TIO N O F S H O R T -L IV E D R A D IO ISO T O PE S

T h e a c tu a l p ro d u c tio n of th e ra d io is o to p e in th e r e a c to r i s on ly a p a r t o f th e p r o b le m . H av ing p ro d u c e d th e s h o r t - l iv e d n u c lid e , th e r a c e to g e t i t in to th e f in a l s y s te m w h e re i t i s to b e u se d s t a r t s th e in s ta n t th e t a r g e t i s rem o v e d f ro m the r e a c to r . E v e ry s te p f ro m th is point on m u st be planned and ex ecu ted w ith the p re c is io n of a w e ll-d r i l le d m il i ta ry un it. No o p era tio n sh o u ld b e m a d e in s e q u e n c e th a t c a n be done e i th e r a h e ad of t im e o r c o n c u r r e n t ly w ith o th e r o p e ra tio n s . T hus, sh ie ld e d c a r r i e r s a r e lo ca ted a t the sa m p le d is c h a rg e s ite , p e rs o n n e l a r e re a d y , and tr a n s p o r ta t io n i s w aiting ; a t th e sh ie ld e d c h e m ic a l c e ll , a l l m a te r ia l s , eq u ip m en t, and p e rs o n n e l a r e r e a d y to go.

W hile t r a n s p o r ta t io n a t ORNL fro m th e r e a c to r s to th e c h e m ic a l c e l l s i s d one b y t r a n s f e r to sh ie ld e d c a r r i e r s an d su b s e q u e n t d is c h a r g e in th e c e lls , i t would be d e s ira b le to have a f a s te r t r a n s f e r , such a s a d ire c t pneum a tic tu b e . C o n s id e ra t io n o f th i s i s r e c o m m e n d e d f o r r a d io is o to p e p r o d u c tio n w o rk to th o s e b u ild in g f a c i l i t i e s w h e re su c h a t r a n s f e r f a c i l i ty i s f e a s ib le . A t p r e s e n t , we u s e su c h t r a n s f e r s y s te m s on ly f o r a c tiv a tio n a n a ly s i s and r e s e a r c h s a m p le s .

T h e s im p le s t , f a s te s t p r o c e s s in g m e th o d i s s im p le d is s o lu tio n of th e ta rg e t m a te r ia l , and one th e re fo re a tte m p ts to do th is in ev e ry ca se po ssib le . T a r g e t s o f e x t r e m e ly p u re e le m e n ta l m a te r i a l , o x id e , o r c a r b o n a te a r e t h e r e f o r e p r e f e r r e d . T h e t a r g e t s a r e d is s o lv e d u s u a l ly in e i th e r H C l o r H N 03, o r w hen n e c e s s a r y a co m b in atio n of both . E x c e s s ac id is v o la tilize d , and th e sa m p le i s m ade up to the re q u ire d s tre n g th a s e s tim a te d f ro m c a lc u la t io n s o r p r io r p r o c e s s in g . H ow ever, f a s t p ro c e s s in g of a m o re co m p lex sy s te m i s so m e tim e s re q u ire d , a s , fo r exam ple , in p ro c e ss in g B r S 2 . K Br is a c o n v e n ie n t t a r g e t m a te r ia l , bu t K42 i s p ro d u c e d in ad d itio n to B r 8 2 . F o r th i s , tw o io n ex c h an g e c o lu m n s in s e r i e s a r e u se d . T he K B r s o lu t io n i s p a s s e d f i r s t th ro u g h a h y d r o g e n - fo rm c a tio n ex c h an g e c o lu m n , th u s r e m oving th e K42 and s u b s titu tin g n o rm a l H, and th e e fflu en t H B r82 i s p a s s e d a s p o ta s s iu m - f o r m e x c h a n g e r , s u b s t i tu t in g n o r m a l К f o r th e h y d ro g e n , g iv in g K B r82 in s l ig h t ly a c id ic w a te r s o lu t io n .

M ore c o m p lic a te d p ro c e d u re s a ls o c a n be done ra p id ly , a s , fo r e x a m p le , th e s e p a r a t io n o f c a r r i e r - f r e e As'1'1 :

Ge(n,T)— s»-Ge77-ji^- As77


A rs e n ic - f r e e g e rm a n iu m oxide is i r ra d ia te d and then d isso lv ed in 12 N HCl and H2O2 to p re v e n t re d u c tio n of A s ^ to As3+ w ith p o ss ib le lo s s of a r s e n ic . T h e g e rm a n iu m i s d i s t i l le d off, h o ld in g th e a r s e n ic b a c k w ith H2O 2 in th e A s 5+ f o rm . T h e r e s id u e of A s 77 i s r e d u c e d in H C l c o n te n t an d d ilu te d to s t r e n g th (3 N H C l).

By f a s t a s s a y te c h n iq u e s , th e s a m p le p ro d u c t s o lu t io n s a r e a n a ly se d , p r in c ip a l ly f o r c o n c e n tra t io n , an d th e sp e c if ic a c t iv i ty i s c a lc u la te d f ro m known ta r g e t w e ig h ts . T he m a in m e th o d s of a n a ly s is a r e g iv e n in T a b le H. T he c a l ib ra te d g am m a ion c h a m b e r i s th e f a s te s t a s s a y m ethod and i s u se d w h e n e v e r p o s s ib le . T h e g a m m a s p e c t r u m i s ta k e n w h e r e v e r p o s s ib le to c h e c k on im p u r i t i e s . A k ey f e a tu r e of th e f a s t h an d lin g p r o c e d u r e i s th a t a s iz a b le sa m p le is h eld fo r fu r th e r a n a ly s is a f te r the m o st e s s e n tia l an a ly se s h av e b e e n m a d e . T h e p r o d u c ts a r e sh ip p e d , an d w h ile th e y a r e e n r o u te , m o re c o m p le te a n a ly tic a l w o rk i s c o m p le te d to d e te c t im p u r i t ie s o r d e t e r m in e w h e th e r s ig n if ic a n t e r r o r s h av e b een m ad e in th e a s s a y s o r in c a lc u la tin g sp e c if ic a c tiv i ty . If v a r ia t io n s a r e found, o r if th e u s e r n e e d s m o re in fo rm a tio n , th e r e s u l t s a r e te le g ra p h e d to h im , o ften a r r iv in g b e fo re th e a c tu a l sh ip m e n t.

6. EN R IC H ED ISO T O PE F O R T A R G E T M A TERIALS

A g ain r e f e r r i n g to T a b le I, w e sh o u ld lik e to c a l l a t te n tio n to a n o th e r f a c to r th a t i s o ften o f im p o r ta n c e — n am e ly , th e iso to p ic e n r ic h m e n t o f th e ta r g e t a to m in c e r ta in e le m e n ts . T h is shou ld be c o n s id e re d w hen th e ab u n dance of th e ta rg e t a to m in an e lem en t is le s s than 50%, p a r tic u la r ly in those c a s e s w h e re th e v a lu a b le t a r g e t m a te r i a l c a n be r e c la im e d an d u s e d . An ex am p le of th is l a t te r p o in t would be th e c a se w h ere th e i r r a d ia te d ta rg e t i s u s e d d i r e c t ly a s a s p e c ia l s o u r c e o f r a d ia t io n , o r in a c h e m ic a l s y s te m w h e re i t i s n o t d ilu te d w ith th e n o r m a l e le m e n t and c a n be c h e m ic a l ly r e c o v e re d .

U se o f i s o to p ic a l ly - e n r ic h e d t a r g e t m a te r i a l co u ld b e o f e x c e p t io n a l in te r e s t to th e u s e r of th e s m a ll r e s e a r c h r e a c to r . O p era tin g a t low p o w er an d w ith th e c o n se q u e n t low flu x , o n e m a y b e w ith in a f a c to r o f 2 to 10 of h av in g th e r e q u i r e d s p e c if ic a c t iv i ty on a s h o r t - l iv e d r a d io is o to p e f o r a n e x p e r im e n t. W hile i t m ay n o t be f e a s ib le to r a i s e th e n e u tro n flux , one ca n ac h ie v e th e s a m e r e s u l t by u s in g an e n r ic h e d t a r g e t in c e r ta in c a s e s w h ere th e t a rg e t n u c lid e o c c u r s in low n a tu ra l abundance . E x a m p le s m ay be no ted in T a b le I f o r so m e o f th e s h o r t - l iv e d is o to p e s u n d e r d is c u s s io n , a s , f o r e x a m p le , Ni65( Si31, Z n 71, С е137, К 42, and Hg197m*; n u m e ro u s o th e r c a s e s e x is t f o r th e lo n g e r - l iv e d is o to p e s .

7. SUMMARY

T h e s m a l l r e s e a r c h r e a c to r h a s a v e r y d e f in ite an d im p o r ta n t r o le to p la y in r a d io is o to p e p ro d u c tio n — p a r t i c u l a r l y f o r th e r a d io i s o to p e s w ith h a l f - l iv e s o f th e o r d e r o f m in u te s to д few h o u r s , and f o r th e so m e w h a t lo n g e r - l iv e d s p e c ie s in th o s e lo c a l i t i e s w h e re c o m m e r c ia l r a d io is o to p e p r e p a ra t io n s f ro m h ig h -flu x r e a c to r s a r e n o t a v a ila b le . P ro d u c tio n eq u ip -

46 P. С . AEBERSOLD and A. F. RUPP

m e n t an d p r o c e d u re s u s e d a t th e l a r g e r r e a c to r s i t e s , su c h a s p n e u m a tic and h y d ra u lic tu b e s fo r i r r a d ia t io n s , f a s t p ro c e s s in g , and a n a ly s is , should be u s e fu l fo r s im i la r w o rk a t th e s m a l le r r e a c to r s . In so m e c a s e s , w h ere flux le v e l i s d e f ic ie n t , i t c a n be c o m p e n sa te d fo r by u s e of e n r ic h e d ta r g e t m a te r ia l s .

R E F E R E N C E S

[1 ] KNOLL, P. , "T he Production of rad ioactive Isotopes", Chem . Tech. 12 (1960) 25.[2 ] COMITATO NAZIONALE RECHERCHE NUCLEARE, International e lectron ic and nuclear Review, V The

N uclear Congress 2 (1960).[3 ] ALLEN, R. A. e t a l . , Radioisotope D ata, AERE-R2938 (2nd e d .) (1961).[4 ] ARLMAN, J. J . , "Production, Preparation and Delivery of rad ioactive Isotopes", A tom energie 2 (1960)

162.[5 ] FISHER, C . , "Laboratory spec ia lized in th e Production of R adioelem ents", Bull. Inform . S ci. T ech .

(Paris) 51 (1961) 17.[ 6] BREZHNEVA, N .E . and OZIRANER, S. N ., R adioactive Isotopes and th e ir Production under neutron

Irrad iation , Review Series IAEA _15 (1961).[7 ] FISHER, C . , Production des R adioélém ents a rtif ic ie ls (F rance), A cta E lectrónica (1959) 1 -9 .[ 8] DIZDAR, Z. , Production of radioactive Isotopes a t the Institute "Boris K idric", V inca. Nova Proizvodnja

_U (1960) 228.[9 ] HAUCK, G ., "Radioisotopes from sm all Reactors” , A tom w irtschaft 6 (1961) 485.

[10 ] OSTERLUNDH, C. G . . "Production of rad ioac tive M aterial in Sw eden", Т ек. Tidskr. 90 (1960) 1031.[11 ] CONSTANT, R ., "T he Production and use of'Radioelem ents in Belgium ", Rass. Intern. E llectronica e

N ucleare , 7th Congr. N ucleare, Rome (1960) 53.[1 2 ] MARCINOWSKI, H. J . , "W orld Isotope P roduction". A tom w irtschaft 6 (1961) 509.[13 ] CASWELL, A ., "Laboratory Production of short-lived Isotopes", Am. J. Roentgenology 87 (1962) 183.[14] KING, E. R. e t a l . , "The Production and m edical Applications of short-lived Radioisotopes", Radiology

71 (1958) 860.E15] BÜCHANAN, J. D. e t a l . , Production o f Radioisotopes for Research (T riga Reactor), G eneral Dynamics

Corp. Pam phlet.[16] MEINKE, W .W ., "Techniques for fast Radiochemistry", Proc. Int. Conf. on Trends A ctivation Analysis

(1961) 36.[1 7 ] KUSKA, Y. and MEINKE, W .W ., Rapid rad iochem ica l Separations, Rep. N A S-NS-3104, N at.,R es.

C ouncil, W ash ., D. C.[1 8 ] SHARP, A. and SCHM ITT, R. A. , Studies of the S z ila rd -C halm ers Processes, Rep. G A -910, O ff. of

T ech . Services, D ept, of C om m erce, W ash., D. C .

D I S C U S S I O N

L . G. E R W A L L (C h a irm a n ) : * Do th e f ig u r e s f o r s p e c if ic a c t iv i ty in T a b le I r e f e r to th e s a tu r a t io n a c tiv i ty ?

P . C . A EBERSO LD : Y es , th e th e o re t ic a l s a tu ra tio n a c tiv ity . It should be n o te d h o w e v e r th a t , in th o s e c a s e s in w h ich th e p ro d u c t r a d io is o to p e h a s a c r o s s - s e c t i o n f o r n e u tro n a b s o rp t io n c o m p a ra b le to o r l a r g e r th a n th e t a r g e t n u c lid e , th e s a tu ra t io n a c tiv i ty w ill be l e s s th a n th a t c a lc u la te d f ro m th e u su a l fo rm u la involv ing only the ta rg e t m a te r ia l , and w ill be rea ch ed s o o n e r . T h is r e s u l t s f ro m " b u rn -u p " o r " b u rn -o u t" o f th e p ro d u c t r a d io iso to p e and th e e ffe c t i s m o re p ro n o u n ced w hen one u s e s v e r y h igh f lu x e s . A s c a n b e s e e n f ro m T a b le I th i s e f fe c t i s v e r y p ro n o u n c e d f o r A u la8.

J . L A L E R E : Y ou s a y th a t th e H F IR r e a c to r w ill g iv e v e r y la r g e sp e c if ic a c tiv i t ie s , c o rre sp o n d in g to th e rm a l n e u tro n f lu x es of the o r d e r of


10l5n /c m 2 s . I w ou ld l ik e to know w h e th e r th i s f lu x i s n o n - p e r tu r b e d o r w h e th e r i t i s p e r tu r b e d by th e p r e s e n c e o f th e i r r a d i a t e d s a m p le s ?

P . C . A EB ER SO LD : If one in tro d u c e s in to a n e u tro n flux a s ig n if ic a n t am oun t of a t a rg e t n u c lid e having a high a b so rp tio n c ro s s - s e c t io n , th a t flux w ill be p e r tu r b e d — be d e p r e s s e d — in th e im m e d ia te v ic in ity . H ow ever, if th e r e a c to r h a s p len ty of e x c e s s re a c tiv ity , the pow er le v e l can be r a is e d to m ake up fo r the d e p re s s io n of re a c tiv ity f ro m a l l th e ta rg e t m a te r ia ls in t r o d u ced in to th e r e a c to r . T he H FIR i s sp e c if ic a lly d e s ig n e d f o r iso to p e p r o d u c tio n an d to h av e a p r a c t i c a l o r u s a b le f lu x of g r e a t e r th a n 1015n /c m 2 s . T he p u rp o se o f th e ’’is la n d " of w a te r in th e c e n tr e o f the r e a c to r c o re — th e n e u tro n t r a p — i s so th a t m an y ta r g e t s ca n be i r r a d ia te d s im u lta n e o u s ly a t th e h ig h e s t flux .

J . HOSTE: Do you have any p ro b le m s w ith the p u rity of y o u r ir ra d ia te d t a r g e t s ? W e h av e e x p e r ie n c e d th a t ev e n w ith s o - c a l le d s p e c tr o s c o p ic a l ly - p u re m a te r ia l s s m a ll im p u r i t ie s ca n g ive r i s e to a la rg e b u ild -u p of r a d io a c tiv e m a te r ia l s .

P . C . A EBERSO LD : Y es , of c o u rs e , im p u r i t ie s in the ta r g e t m a te r ia l a r e a ls o i r r a d ia te d an d m ay p ro d u c e u n d e s ira b le c o n ta m in a tin g a c t iv i t ie s , w hich a r e p a r t ic u la r ly tro u b le so m e if th ey a r e lo n g -liv e d o r have ra d ia tio n s w hich in te r f e r e w ith m e a s u re m e n t of th e d e s i r e d ra d io is o to p e . S o m e tim e s s p e c tro s c o p ic a l ly -p u re o r even c h e m ic a l-g ra d e ta r g e t m a te r ia ls a r e s a t i s f a c to ry , bu t th is ca n b e s t be d e te rm in e d by a c tiv a tio n t e s t s of th e m a te r ia l . Only by e x p e r ie n c e and te s t in g d o es one le a r n to ob ta in the b e s t t a r g e t m a te r i a l f o r e a c h s p e c if ic r a d io is o to p e . A s p o in te d o u t in o u r p a p e r , w hen one u s e s v e r y h ig h f lu x e s in th e ra n g e o f 1014-» 1 0 15n /c m 2 s , th e p u r i ty and s ta b i l i ty o f th e t a r g e t m a te r i a l b e c o m e s e x t r e m e ly im p o r ta n t .

C . T A Y LO R : W ith r e g a r d to th e u s e o f th e s e s p e c t r o s c o p ic a l ly - p u re m a te r ia ls , I should lik e to m en tion th a t we have fo r som e tim e been checking a l l t a r g e t m a te r i a l s by a t r i a l a c tiv a tio n a n a ly s i s . In so m e c a s e s we h av e found lo w e r - g r a d e m a t e r i a l to b e m o r e s u i ta b le f o r i r r a d i a t i o n th a n th e sp e c tro s c o p ic a lly -p u re m a te r ia l , and c o n s id e r it e s s e n t ia l to m ake an ana ly s i s o u r s e lv e s in e v e ry c a s e . A m in u te t r a c e of a su b s ta n c e of h igh n e u tro n c r o s s - s e c t io n m ay not be re g a rd e d a s im p o rta n t when sp e c tro sc o p ic a n a ly s is i s done, and m ay no t be re p o r te d , but i t w ill g ive tro u b le when the su b stan ce is u sed fo r ir ra d ia t io n and it i s fo rtu n a te ly e a sy to d e tec t by a s im p le a c tiv a tio n a n a ly s is .

P . C. A EB ER SO LD : I a g re e e n t i r e ly w ith D r. T a y lo r , and a p p re c ia te h i s m a k in g th e s e a d d e d c o m m e n ts . W hen w e do fin d a p a r t i c u l a r l y good so u rc e o f ta rg e t m a te r ia l f o r p ro d u c in g a sp e c if ic iso to p e th a t i s fre q u e n tly re q u ire d , we s to r e enough to m e e t fu tu re n ee d s o v e r a c o n s id e ra b le p e rio d . The s a m e i s t r u e when it i s n e c e s s a r y to p u rify ta rg e t m a te r ia ls in advance; i t i s w e ll to m ake enough fo r fu tu re n e e d s so th a t th e q u a lity w ill con tinue to be u n ifo rm .

PROJET D’UNE INSTALLATION DE TRAITEMENT CHIMIQUE DE RADIOÉLÉMENTS A

COURTES PÉRIODES

- M. DOUIS ET J. VALADECENTRE D’ÉTUDES NUCLÉAIRES, SACLAY, FRANCE


DESIGN OF A CHEMICAL PROCESSING APPARATUS FOR RADIOISOTOPES OF SHORT HALF-LIFE . I t has appeared to us useful to m ake suggestions to radiochem ists having a t their disposal a sm all reactor (e . g . , 101? п/ c m í s flux) regarding which radioisotopes they can prepare and the m inim um equ ipm ent required .

The paper comprises three m ain parts:1. Possible radioisotopes, which m ay be divided in to two categories:

(a) radioisotopes for m ed ica l usçs, including: N a24, K42, Br82, C u64, As76, Hg1917 and co llo ida l. Au19B ; and

(b) radioisotopes for scien tific or industrial uses, including in addition to the above-nam ed : Sb122 As77, Mn56 and Au198 (chloride).

2. C hem ica l processing, in which two categories of radioisotopes em erge:(a) the category involving simple solution, norm ally requiring either cold dissolution in water or dilute

acid or ho t dissolution in concentrated acids. This category includes: N a24, K42, Br12, Hg197, Sb122 , M n56 and Au198 (chloride).

(b) The category involving com plex separations or transform ations, in which fa ll preparations by Szilard-C halm ers e ffec t, reactions ( n , p ) , (n , y ) , followed by 0 -d ecay or form ation of colloids. The following m a y b e mentioned: C u64, Asîé , As77 and co llo idal AuIa* . and

3. Preparation areas. I t is essential that these radioisotopes be prepared in le ak -tig h t and shielded areasand be grouped according to their affinities.We accordingly suggest an apparatus consisting of 3 cells 2 m in length by 1 m in depth, linked together

by a conveyor and used, e . g . , for the following processes: 1st cell: Introduction of containers, opening and preparation of Na24, к * 2 , and Br82. 2nd cell: Preparation of two out of the following three radioisotopes : C u«* , AsT6 and co llo ida l Au*» ; and 3rd cell: Bringing in to solution o f radioisotopes for various uses and p reparation of Hg197.

PROJET D'UNE INSTALLATION DE TRAITEMENT CHIMIQUE DE RADIOELEMENTS A COURTES PERIODES,I l a paru intéressant de proposer IL des radiochim istes qui ont la possibilité d* u tiliser un p e ti t réacteu r (par exem ple flux de 10*2 n /cm î-s) quels sont les rad ioélém ents qu 'ils peuvent préparer e t quel est le m a té rie l m inim um qui sera nécessaire.

Le m ém oire com prend trois parties principales :1. Les radioélém ents possibles: Ils peuvent ê tre classés en deux catégories:

a) Les radioélém ents à usages m édicaux parm i lesquels nous citonsj le sodium -24, le potassium -42, le b rom e-82, le cu iv re-64 , l*arsenic-76, le m ercure-197 e t l 'o r c o llo ïd a l-198.

b) Les radioélém ents à usages scientifiques ou industriels, en plus de ceux déjà cités: l'an tim oine-122, l*arsenic-77, le manganèse-56, l*or-198 (chlorure).

2. Les traitepients chimiques! Il apparaît deux catégories de radioéléments:a) Les mises en solutions simples qui dem andent la plupart du tem ps, soit une dissolution dans l*eau

ou en ac id e d ilué à froid, so it une dissolution dans des acides concentrés à chaud. Entrent dans cette catégorie: le sodium -24, le potassium -42, le brom e-82, le m ercure-197, l'an tim om e-122 , le m anganèse-56, l'o r-198 (chlorure) •

b) Les séparations ou les transformations com pliquées. C 'e s t le cas des préparations par e ffe t Szilard - C halm ers, des réactions ( n , p ) , (n ,y ) suivies de décroissances B ou de form ation de co llo ïdes. Nous pouvons c ite r: le cu iv re -6 4 , l‘arsen ic-76 , l*arsenic-77, Ieor collo‘ida l-198 .

3. Les enceintes de préparations. Ces radioélém ents doivent â tre préparés dans des encein tes é tanches e tprotégées, e t groupés suivant leurs affinités.

49

50 M. DOUIS e t L VALADE

Aussi nous proposons une insta llation com prenan t trois boîtes de 2 m de long sur 1 m de profondeur reliées entre e lles par un convoyeur, dont les attributions seraient: 1ère b o îte : Introduction des containers, dessertissage e t préparation du sodium -24, potassium -42 e t b rom e-82 ; 2èm e bo tte t Préparation de deux des trois radioélém ents suivant; cuivre-64, arsénic-76, or colloïdal -198; 3ème b o îte : Mise en solution des radioélém ents â usages divers e t préparation du m ercure-197.

ПРОЕКТ УСТАНОВКИ ДЛЯ ХИМИЧЕСКОЙ ОБРАБОТКИ КОРОТКОЖИВУЩИХ РАДИОЭЛЕМЕНТОВ. Представилось интересным показать радиохимикам, имеющим в своем распоряжении небольшой реактор (например, с потоком 101г н/см2/сек), возможности получения ряда радиоэлементов минимальными средствами.

Эта работа состоит из трех основных частей:1. Возможные радиоэлементы ; подразделяются на две категории:а) радиоэлементы для применения в медицине, к которым относятся: натрий-24, калий-42,бром-82,

медь 64, мышьяк-76, ртуть-197 и коллоидальное золото-198;б) радиоэлементы для научного или промышленного применения, к которым, помимо вышеуказанных,

относятся: сурьма-122, мышьяк-77, марганец-56, золото-196 (хлористое).2. Химическая обработка; подразделяется на две группы:а) переведение в истинные растворы, что требует значительного количества времени для рас

творения в воде, разбавленной кислоте на холоду, либо растворения в концентрированных кислотах при нагревании; в эту группу входят: натрий-24, калий-42, бром-82, ртуть-197, сурьма-122, марганец-56 и золото-198 (хлористое);

б) процессы выделения или сложных превращений, куда относятся методы выделения, основанные на эффекте Сциларда-Чалмерса, реакции (п,р), (п, у) с последующим бета-распадом иди образованием коллоидов; сюда входят: медь-64, мышьяк-76, мышьяк-77 и коллоидальное золото-198;

3. Защитные камеры для предварительной обработки, группируются согласно их свойствам. Предлагается установка, состоящая из трех камер длиной 2 и глубиной в 1 м, которые соединены между собой конвейером и играют роль : 1-я камера: введение контейнеров, выемка и приготовление натрия-24, калия-42 и брома-82; 2-я камера: приготовление двух из трех следующих радиоэлементов: медь-64, мышьяк-76 и коллоидальное золото-198; 3-я камера: растворение радиоэлементов для различного применения и приготовление ртути-197.

PROYECTO PARA UNA INSTALACION DE TRATAMIENTO QUIMICO DE RADIOELEMENTOS DE PERIODO CORTO. Los autores consideran conveniente indicar a los radioquímicos que tengan la posibilidad de u tilizar un reactor pequeño (por e jem plo , de un flujo de 10*2 n /cm ^ s ) qué radioelem entos pueden preparar y cuál es e l m ateria l m ínim o que precisarán para e llo .

La m em oria com prende tres partes principales:1. Radioelementos posibles. Estos pueden clasificarse en dos categorías:

(a) Radioelementos para fines médicos, entre los que se citan: el sodio-24, e l potasio-42, el bromo-82, e l cobre-64, e l arsénico-76, e l mercuxio-197 y e l oio-198 coloidal.

(b) Radioelementos para fines científicos o industriales,además de los ya mencionados: e l antim onio-122, e l a rsén ico-77 , e l m anganeso-56 y e l oro-198 (c lo ru ro).

2. T ratam ientos quím icos. Tam bién a este respecto , los radioelem entos se pueden dividir en dos c a te gorías:

(a) La simple disolución, que casi siempre se efectúa en agua o en ácidos diluidos, en frío, o en ácidos concentrados, en calien te . A esta categoría pertenecen: e l sodio-24, e l potasio-42, e l brom o-82, e l m ercurio-197, e l antim onio-122, e l manganeso-56 y e l oro-198 (cloruro).

(b) Las separaciones o las transform aciones com plicadas; pertenecen a esta c lase las preparaciones obtenidas por efecto Szilard-Chalm ers y por reacciones (n ,p ) y (ñ ,y ) seguidas de desintegraciones Во de la,form ación de coloides. Como ejem plos pueden citarse: e l cobre-64, e l arsénico-76, e l arsénico-77, y e l oro-198 coloidal.

3. Recintos de preparación . Estos radioelem entos deben prepararse en recintos estancos y protegidos y agruparse según sus afinidades.Les autores proponen una instalación que comprende tres cajas de 2 m de largo por 1 m de profundidad,

unidas en tre sí por un transportador y cuyas finalidades serían las siguientes; Prim era caja : Introducción de los recipientes, vaciado y preparación del sodio-24, del potasio-42 y del bromo-82; Segunda caja: Preparación de dos de los tres radioelem entos siguientes: cobre-64 , arsénico-76, oro-198 coloidal; T ercera caja: Disolución de los radioelem entos destinados a fines diversos y preparación del m ercurio-197.

PROJET D’UNE INSTALLATION DE TRAITEMENT CHIMIQUE 51

INTRODUCTION

D u ra n t c e s d e r n iè r e s a n n é e s , p lu s ie u r s s t a g ia i r e s de d iv e r s e s n a t io n a l i té s ont s é jo u rn é d an s n o s la b o r a to i r e s . Une q u e s tio n n o u s é ta i t p o sé e f ré q u em m en t: « N o tre pays, ou n o tre in s titu t ou n o tre u n iv e rs i té v ien t d ’av o ir un r é a c t e u r . N ous v o u d r io n s p r é p a r e r t r è s r a p id e m e n t q u e lq u e s r a d io é lé m e n ts , nous h é s ito n s e t nous ne sav o n s p as p a r le sq u e ls c o m m e n c e r . De p lu s , no u s a im e r io n s c o n n a î t r e l ’im p o r ta n c e du m a té r i e l n é c e s s a i r e » .

C om pte tenu des dem andes d es u t i l is a te u r s , a p rè s a v o ir p a s sé en rev u e un ca ta lo g u e de ra d io é lé m e n ts , nous avons pu f ix e r n o tre cho ix s u r une d iz a in e dont la p lu p a r t p eu v en t ê t r e u t i l i s é s en m é d e c in e . P o u r c e r ta in s , la p ré p a ra t io n c o n s is te s im p le m e n t en une m is e en so lu tio n ; p o u r d ’a u t r e s , il e s t n é c e s s a i r e d ’e f fe c tu e r une sé p a ra tio n ch im iq u e et de c o n s tru i re un p e tit a p p a r e i l q u i, é v id e m m e n t, d o it ê t r e p ro té g é e t c o m m a n d é à d is ta n c e .

N ous a l lo n s , au c o u r s d e c e t e x p o sé , e s s a y e r de d é f in i r :1. Q u e ls so n t l e s r a d io é lé m e n ts s u s c e p t ib le s d ’ê t r e c h o i s is .2. Q u e ls t r a i t e m e n ts c h im iq u e s i l s d o iv e n t s u b ir .3. Q u e l m a té r i e l e s t n é c e s s a i r e à l e u r p r é p a r a t io n .

1. L E S R A D IO É L É M E N TS S U S C E P T IB L E S D ’Ê T R E CHOISIS

Un r é a c te u r de r e c h e r c h e s ne fo n c tio n n e p a s to u jo u r s d ’une m a n iè r e ré g u liè re , sa n s a r r ê t , pendant une sem ain e p a r exem ple . Il fonctionne s e u le m e n t q u e lq u es h e u re s p a r jo u r ou d u ra n t d e s p é r io d e s de 24 h e u r e s . C e ttes i tu a t io n v a é l im in e r to u t de su ite d e s r a d io é lé m e n ts c o m m e l ’io d e -1 3 1 ,le p h o sp h o re -3 2 , le s o u f re -3 5 . Il r e s t e ce p e n d a n t q u e lq u e s r a d io é lé m e n ts pouvant ê t r e c h o is is e t qu i, de p lu s , p ré s e n te n t l ’avan tage d ’a v o ir une u t i l i sa tio n m é d ic a le . P a r m i c e u x -c i nous pouvons c i t e r :

L e sod iu m -2 4

P o u r un e i r r a d ia t io n de 1 g de so d iu m p en d a n t 24 h à u n f lu x de 1 0 ^ n /c m 2 , s n o u s o b te n o n s 250 m e . U ne so lu tio n iso to n iq u e c o n tie n t 9% 0

de c h lo ru r e de so d iu m ; i l fa u t donc 3,5 m g de so d iu m p a r m i l l i l i t r e . A la s o r t ie de p ile , nous avons 250 juc /m g, s o it p o u r 3,5 m g, 880 цс /m l . M êm e a p r è s d eux p é r io d e s , c e t te so lu tio n e s t e n c o re u t i l i s a b le .

L e p o ta s s iu m -4 2

P é r io d e 15 hb ê ta : 1 ,3 9 -4 ,1 9 MeV gam m a : 1,37 - 2,76 MeV 23Na (n, y) 24Na 0 ,54 b

E n e rg ie de ray o n n em en t

R éac tio n de fo rm a tio n S ection e ff ica ce

E n e r g ie d e ra y o n n e m e n t:

R é a c tio n d e fo rm a tio n S ec tio n e f f ic a c e

P é r io d e : 12,5 h b ê ta : .2,0 - 3 ,6 M eV

: g a m m a : 0 ,3 2 - 1,51 M eV : « K (n, y) 42k : 0 ,09 b

52 M. DOUIS e t J. VALADE

P o u r une i r r a d ia t io n d e 1 g de p o ta s s iu m p en d a n t 24 h à un f lu x de 1012 n /c m 2 - s nous ob tenons 27 m e . Une so lu tio n iso ton ique co n tien t 12% 0

d e c h lo r u r e d e p o ta s s iu m , s o i t 6 ,3 m g de p o ta s s iu m .p a r m i l l i l i t r e . A la s o r t ie de p ile , nous avons 27 цс/mg, so it p o u r 6,3 m g, 170 цс/ml; la so lu tio n p eu t ê t r e fa c ile m e n t u t i l is é e ju s q u ’à 50 /u c /m l.

L e b ro m e -8 2

P é r io d e 36 h, , bêta 0,45 MeVE n e rg ie de ray o n n em en t: gam m a: ^ ^ ^ ^ M ey

0,83 - 1,04 - 1,32 - 1,475 MeVR é ac tio n de fo rm a tio n : 81B r (n, y) 82B rS ection e ff ic a c e : 1,63 b

P o u r une ir ra d ia tio n de 1 g de b rom e pendant 24 h à un flux de 1012n /cn#*sn o u s o b te n o n s 122 m e . P o u r u s a g e m é d ic a l , i l e s t c o r r e c t d e t e r m i n e r à l a co n c en tra tio n de 20 à 50 m g de b rom e p a r m il l i l i t r e et d ’av o ir une ac tiv ité d e 2 à 5 m e /m l.

L e m e rc u re -1 9 7

P é r io d e : a) 24 h la7Hgb) 65 h isiHg

E n e rg ie de rayonnem ent:

b ê ta : a) С E b) C E

gam m a: a) 0,133 et 0,164 MeV b) 0,078 e t 0,912 MeV

R éac tion de fo rm a tio n : 196Hg (n, y) 197Hg ^ ^ i97Hg

S ection efficace : 4,5 b

P o u r une i r r a d ia t io n de 1 g de m e rc u re pendan t 24 h à 1012 n /c m 2 *s n o u s o b tenons 190 m e . Il e s t in té r e s s a n t de te r m in e r à la c o n c e n tra tio n de 5 m g /m l e t d ’a v o ir une a c tiv i té de l ’o r d re de 1 m c /m l .

L e c u iv r e - 64

P é r io d e : 12,8 hb ê ta f : 0,57 MeV

0+ : 0,65 MeV C E

g am m a : 1,34R é ac tio n de fo rm a tio n : 63Cu (n, y) 64cuS ec tio n e ff ic a c e : 3,12 b

E n e rg ie de ray o n n e m en t:

P o u r que ce ra d io é lé m e n t so it u t i l is a b le en m é d e c in e , i l d o it s u b ir un e n r ic h is s e m e n t d e l ’a c t iv i té s p é c if iq u e p a r l ’e f fe t S z i la r d - C h a lm e r s . On i r r a d ie de la ph ta locyan ine de cu iv re dont la m o lécu le ren fe rm e 1 1 % de cu iv re .

PROJET D'UNE INSTALLATION DE TRAITEMENT CHIMIQUE 53

P o u r 1 g de p h ta lo c y a n in e de c u iv re à 1012 n / c a ? • s p e n d a n t 24 h n o u s o b ten o n s 51,6 m e de c u iv re . L e ren d em en t ch im ique de l ’o p éra tio n é tan t d ’enviro n 50%, n o u s te rm in o n s av e c 25 m e d a n s 10 m l d e so lu tio n p a r e x e m p le . L a so lu tio n f in a le a un e a c t iv i té s p é c if iq u e s u p é r ie u r e à 50 m c /m g .

L ’a r s e n i c - 76

P é r io d e

E n e rg ie de rayonnem en t

R éac tio n de fo rm a tio n S ection e ffica ce

26,5 hb ê ta : 0,36 - 1,76 - 2,41 - 2,97 MeV gam m a: 0,56 - 0,65 - 1,21 - 2,06 MeV 75A s (n, y) 76As 5,4 b

C om m e le c u iv r e - 64, ce ra d io é lé m e n t do it su b ir un e n r ic h is se m e n t p a r l ’e ffe t S z ila rd -C h a lm e rs .

L a c ib le p eu t ê t r e l ’a c id e c a co d y liq u e dont l a m o lé c u le r e n f e r m e 55% d ’a r s e n ic . A vec 1 g d ’a c id e c a co d y liq u e i r r a d i é à un flu x de 1012 n /c m 2 • s p en d an t 24 h no u s o b te n o n s 312 m e d ’a r s e n i c - 76. L e re n d e m e n t ch im iq u e é ta n t de 35%, n o u s te rm in o n s av e c 110 m e d an s 30 m l e n v iro n . L ’a c t iv i té sp é c if iq u e e s t s u p é r ie u r e à 20 m c /m g .

L ’o r - 198 c o llo ïd a l

P é r io d e :

E n e rg ie de ray o n n e m e n t:

R é a c tio n de fo rm a tio n : S ec tio n e f f ic a c e :

2,7 db ê ta : 0 ,29 - 0 ,96 - 1,37 M eV g am m a: 0,41 - 0 ,67 - 1,09 M eV 197Au (n, y) 198Au 96 b

L ’o r-1 9 8 e s t u t i l i s é en m é d e c in e so u s f o rm e c o l lo ïd a le . Il f a u t donc, a p r è s i r r a d ia t io n , t r a n s f o r m e r la c ib le d ’o r m é ta l liq u e en c o llo ïd e . P o u r u n e i r r a d ia t io n de 1 g d ’o r pendan t 24 h à un f lu x de 1012 n /c m 2 • s nous ob te n o n s 1,9 c .L a so lu tion fin a le do it av o ir une c o n c en tra tio n en o r de 3,5 m g / m l. L e ren d e m en t c h im iq u e é tan t de 100%, l ’a c tiv ité s e r a de l ’o rd re de 6 m c /m l. Q u e lq u e s a u t r e s r a d io é lé m e n ts t r è s d e m a n d é s d a n s d i f f é r e n ts d o m a in e s p e u v e n t ê t r e f a b r iq u é s a is é m e n t .

L ’o r -1 9 8

П peut ê t r e l iv r é en so lu tion ch lo rh y d riq u e . On peut te rm in e r à 50 cm /m l. L e s c o n d itio n s d ’i r r a d ia t io n so n t l e s m ê m e s que p o u r l ’o r c o l lo ïd a l .

L ’a n t im o in e - 122

P é r io d e :

E n e r g ie de ra y o n n e m e n t:


2 ,74 db ê ta : 0 ,7 4 - 1 ,4 0 - 1 ,9 7 - C E M eV g am m a: 0 ,56 - 0 ,6 9 - 1,26 - 1 ,14 M eV 121Sb (n, y) i 22Sb

'3 ,9 b


Il e s t l iv r é sous fo rm e de c h lo ru re . L o rs q u ’on p ra tiq u e une co u rte i r r a d ia tio n , ce ra d io é lé m e n t co n tien t m o in s de 5% d ’a n tim o in e -124 (période:60d). P o u r 1 g d ’a n tim o in e i r r a d i é à 1 0 i2 n /c m 2 *s p en d a n t 24 h n o u s o b te n o n s 124 m e . U ne so lu tio n f in a le de 2 à 5 m e /m l e s t t r è s c o r r e c te .

L ’a r s e n i c - 77

P é r io d e :

E n e rg ie de ra y o n n e m e n t:

R é a c tio n de f o rm a tio n

S ec tio n e f f ic a c e

39 hb ê ta : 0 ,7g a m m a : 0 ,086 - 0 ,16 - 0 ,25 - 0 ,53 M eV

7 6 G e(n ,y )7 7 G e* -i4 -r 77A s

e t 77G e

0,006 b1 2 h

54 s

77A s

C e ra d io é lé m e n t do it ê t r e s é p a ré ch im iq u em en t de sa c ib le , le g e rm a n iu m . P o u r 1 g de g e rm a n iu m à 1012 n /c m 2 • s p en d a n t 24 h n o u s o b te n o n s 880 цс d ’a r s e n ic - 7 7 à la s o r t ie de p ile . L e re n d e m e n t ch im iq u e de s é p a r a t io n e s t de 90% e t l a so lu tio n f in a le p eu t c o n te n ir 0,1 m e /m l .

L e m a n g a n è se -5 6

P é r io d e :

E n e rg ie de ray o n n e m e n t:


2 ,6 hb ê ta : 0 ,6 5 - 1 ,0 4 - 2,81 M eV g am m a: 0 ,845 -1 ,8 1 - 2 ,1 3 M eV 55Mn (n,-y)56Mn 13,3 b

I l e s t J.ivré en so lu tio n c h lo rh y d r iq u e . Une i r r a d ia t io n de 24 h (ce q u i éq u iv au t à la s a tu ra tio n ) à un f lu x de 1 0 12 n /c m 2 • s donne p o u r 1 g de m a n g a n è se 3,9 c . L a so lu tio n f in a le n ’a p a s d ’a c t iv i té d é te rm in é e .

2 . T R A ITEM EN TS CHIM IQUES

N o u s c o m m e n c e ro n s p a r d é c r i r e l e s p lu s s im p le s , c ’e s t - à - d i r e l e s « m is e s en so lu tio n » . L e p o id s d e s c ib le s t r a i t é e s e s t donné à t i t r e d ’ex em p le .

L e so d iu m -2 4

L a c ib le e s t le c a rb o n a te de so d iu m N a2C 0 3 . I l fa u t d is s o u d re 250 m g de c a rb o n a te de sod ium dans 29 m l d ’ac id e c h lo rh y d riq u e N / 6 , ce qu i donne im m é d ia te m e n t une so lu tio n iso to n iq u e (9%o en N aC l) e t n e u tre . On v é r if ie le pH q u i d o it ê t r e c o m p r is e n t r e 5 e t 7.

L e p o ta s s iu m -4 2 .

L a c ib le e s t le c a rb o n a te de p o ta s s iu m K2CO3 . O n d is s o u t 500 m g de c a rb o n a te de p o ta s s iu m d a n s 44 m l d ’a c id e c h lo rh y d r iq u e N /7 ce q u i donne u n e so lu tio n iso to n iq u e (1 2 %o en KC1) e t n e u t r e . O n v é r i f ie le pH f in a l .


L e b ro m e -8 2

L a c ib le e s t le b ro m u re d ’am m onium NH¿Br. On d isso u t 1 g de b ro m u re d ’am m onium d an s 12 m l de soude N /4 . On chauffe à éb u llitio n pendant 5 m in p o u r c h a s s e r l ’a m m o n ia c . A p rè s r e f r o id is s e m e n t , on n e u t r a l i s e a v e c d e l ’a c id e c h lo rh y d riq u e N (env iron 3 m l) ju sq u ’à pH= 6 ou 7. IL fau t c o m p lé te r à 20 m l avec de l ’eau . On ob tien t une so lu tion n e u tre iso to n iq u e .

L e m e rc u re -1 9 7

L a c ib le e s t l ’oxyde m e rc u r iq u e H gO . On d is s o u t 250 m g d ’o xyde d e m e r c u r e d an s 5 m l d ’a c id e c h lo rh y d r iq u e 1, 6 6 N en c h a u ffa n t lé g è r e m e n t . On n e u tra l is e avec 4 m l de soude 2N et on a jou te 45 m l d 'e a u . Il fau t v é r if ie r le pH q u i e s t de l ’o r d r e de 2 e t a ju s te r le pH à 4 avec de la soude Ñ /1 0 . On o b tie n t a in s i un e so lu tio n iso to n iq u e d e c h lo r u r e m e r c u r iq u e .

L ’o r-1 9 8

L a c ib le e s t de l ’o r de hau te p u re té (99,9999 %). On d isso u t 500 m g d ’o r d an s 1 0 m l d ’eau r é g a le e t on é v a p o re p r e s q u e à s e c p u is on r e p r e n d p a r 20 m l d ’e a u . On a a in s i u n e so lu tio n d e c h lo ru r e d ’o r (A uC l3).

L ’a n t im o in e - 122

L a c ib le e s t de l ’oxyde d ’an tim o ine Sb2 0 4 . On d isso u t 1 g d ’oxyde d’a n t im o in e d an s 20 m l d ’eau r é g a le . On é v a p o re à 2 m l e t on r e p re n d p a r 18 m l d ’eau .

L e p ro d u it f in a l e s t une so lu tion de c h lo ru re d’an tim oine en m ilieu c h lo r hyd rique n o rm a l env iron .

Le m a n g an èse-5 6 .

L a c ib le e s t de l ’oxyde de m an g an è se Mn30 4. On d is so u t 25 m g d ’oxyde de m a n g an è se d an s 5 m l d ’a c id e c h lo rh y d riq u e c o n c e n tré . On év a p o re à une g o u tte e t on r e p r e n d p a r 10 m l d ’e a u . On o b tie n t une so lu tio n de c h lo ru r e d e m a n g a n è s e en m il ie u c h lo rh y d r iq u e d ’a c t iv i té d e l ’o r d r e d e 5 m c /m l .

P o u r le s ra d io é lé m e n ts qu i vont su iv re , le t r a i te m e n t ch im iq u e e s t p lu s co m p lex e e t i l e s t n é c e s s a i r e de m o n te r un p e tit a p p a re il s p é c ia l en v e r r e .

L ’a r s e n ic - 7 6 (v o ir f ig . 1)

Il su b it un e n r ic h is s e m e n t p a r l ’e ffe t S z i la rd -C h a lm e rs [ l ] .O n d is s o u t 5 g d ’ac id e cacody lique d an s 20 m l d ’eau add itionnée de 10 m l d ’une so lu tion de c h lo ru re f e r r iq u e à 1 m g /m l. On p ré c ip ite l ’hydroxyde f e r r iq u e p a r 20 m l d ’am m oniaque c o n c e n tré e a jo u té s gou tte à gou tte . Il fau t e n su ite f i l t r e r , la v e r e t r e d is s o u d re le p ré c ip ité d an s 20 m l d ’ac id e c h lo rh y d riq u e 1N. On p r é c i p ite une seco n d e fo is l ’h yd ro x y d e f e r r iq u e p a r l ’am m o n iaq u e p o u r é l im in e r la to ta lité de l ’ac id e cacody lique . Il fau t la v e r , re d is s o u d re le p ré c ip ité conte n a n t l ’a r s e n i c - 76 s é p a r é d e l a c ib le , d a n s 50 m l d ’a c id e c h lo rh y d r iq u e

56 M. DOUIS et J. VALADE

N /1 0 que l ’on fa it p a s s e r s u r une colonne de r é s in e Dowex 50 (x 8 - 50 - 100 m esh ); le f e r e s t fix é e t l ’a r s e n ic -7 6 sous fo rm e anionique p a s se au t r a v e r s . O n r a s s e m b le d a n s un é v a p o ra te u r , on a jo u te 5 m l d e so u d e 1N e t 10 m l d ’eau oxygénée (à 110 v o lu m e s), p u is on é v a p o re à s e c . F in a le m e n t on r e p re n d p a r 20 m l d ’a m m o n ia q u e N /5 0 . On o b tie n t une so lu tio n d ’a r s é n ia t e d ’am m onium de 3 m c /m l e n v iro n et d ’a c tiv ité spécifique su p é rie u re à 20 m c/m l.

L ’o p é ra tio n d u re six h e u re s .

L e c m v re -6 4 (v o ir f ig . 1)

C e ra d io é lé m e n t su b it, lu i a u s s i , un e n r ic h is s e m e n t p a r l ’e ffe t S z ila rd - C h a lm e rs [2]. On d is s o u t 5 g de ph ta lo cy an in e de c u iv re dans 15 m l d ’ac id e su lfu r iq u e c o n c e n tré ; on a g i te p en d an t 15 m in e t on r e p r é c ip i te l a p h ta lo cy an in e p a r 100 m l d ’e a u . On f i l t r e , on d ilu e à 2000 m l avec de l ’eau e t on f a i t p a s s e r l a so lu tio n s u r un e co lo n n e d e r é s in e D ow ex 50. L e c u i v r e - 64 s é p a r é d e la c ib le s e f ix e ta n d is que le s io n s SO^" so n t é l im in é s . On é lu e le c u iv re avec 150 m l d ’a c id e c h lo rh y d riq u e 6 N, on év ap o re à une gou tte e t on re p re n d p a r 20 m l d ’eau . L a so lu tion fin a le re n fe rm e env iron 2 m c /m l avec une a c t iv i té ’Spécifique s u p é r ie u re à 50 m c /m g . L ’o p éra tio n du re cinq h e u re s .

L ’a r s e n ic - 77

I l do it ê t r e s é p a ré de l a c ib le d ’oxyde de g e rm a n iu m (GeOçKOn d isso u t1 g d ’oxyde d e g e rm a n iu m d a n s 50 m l de so u d e 1N a d d itio n n é e d e 0 ,5 m l d ’ea u oxygénée à 110 v o lu m e s . L a d isso lu tio n se f a i t à f ro id en a g ita n t p en d an t 30 m in . On a jo u te a lo r s 50 m l d ’ac id e c h lo rh y d r iq u e c o n c e n tré en r e f ro id is s a n t le c h lo ru re de sod ium p ré c ip ité . On f i l t r e s u r v e r r e f r i t té num éro 4 s a n s d é p re s s io n , pu is on ag ite le f i l t r a t pendant 45 m in avec 50 m l de t é t r a c h lo r u r e de c a rb o n e . On s é p a r e le s deux p h a s e s . L a co u ch e m in é r a le q u i c o n tie n t l ’a r s e n i c - 77 e s t é v a p o ré e à 1 m l. On a jo u te a l o r s 1 m l d ’a m m o n ia q u e c o n c e n tré e e t 0 ,5 m l d ’e a u o x y g én é e . D e no u v eau , i l fa u t é v a p o r e r à s e c , p u is on r e p r e n d p a r 10 m l d ’a m m o n ia q u e N /5 0 . L a so lu tio n f in a le c o n tie n t l ’a r s e n i c - 77 so u s fo rm e d ’a r s é n ia te d ’am m o n iu m sa n s e n tra în e u r avec une a c tiv i té de l ’o rd re de 0,1 m c /m l. L ’o p é ra tio n d u re s ix h e u re s . Le g e r m a n iu m - 71 q u i se tro u v e d an s la p h ase o rg an iq u e peu t ê t r e ré c u p é ré (on e f fe c tu e u n e e x tra c t io n p a r de l ’eau à chaud , l e 'n G e p a s s e d a n s l a p h a s e a q u e u se ) .

L ’o r -1 9 8 c o l lo ïd a l (v o ir f ig . 1)

C e r a d io é lé m e n t d o it s u b ir une t r a n s f o r m a t io n de so n é ta t p h y s iq u e : p a s s a g e de l ’é ta t m é ta lliq u e à l ’é ta t c o llo ïd a l. On d is s o u t une f e u il le d e 5 0 0 m g d ’o r de h a u te p u re té d an s 4 m l d ’eau ré g a le à chaud . On é v a p o re à se c so u s un v ide de 110 m m de m e rc u re . On re p re n d p a r 50 m l d ’eau et 12,5 m l de soude 1N p o u r f o rm e r le c h lo ra u ra te de sod ium . On f i l t r e et on fa it to m b e r l a so lu tio n g o u tte à gou tte d an s une so lu tio n r é d u c tr i c e c o n te n a n t 20 m l de g é la tin e à 20%, 1,5 m l d ’un g e rm e in a c tif d ’o r co llo ïd a l et de g lu co se , a in s i q u e 48 m l d ’e a u . C e tte o p é ra tio n s ’e f fe c tu e à 70° en a g i ta n t p a r p u ls a tio n . O n r in c e l ’é v a p o r a te u r av ec 15 m l d ’eau a d d itio n n é e de 1 m l de so u d e 1N.


Figu

re

1

Sché

mas

de

prin

cipe

de

la pr

épar

atio

n du

^Cu,

76

As,

198Au

co

lloïd

al.

58 M. DOUIS e t I. VALADE

L a so lu tio n f in a le c o n tie n t e n v iro n 3,5 m g d ’o r p a r m l av ec une a c t iv i té de l ’o r d r e de 6 m c /m l . L ’o p é ra tio n d u re deux h e u r e s e t d e m ie .

3. L e s e n c e in te s de p r é p a ra t io n (v o ir f ig u re 2)

L e s r a d io é lé m e n ts don t n o u s v e n o n s de p a r l e r d o iv e n t ê t r e p r é p a r é s d a n s d e s b o îte s é ta n c h e s , v e n t i lé e s e t p ro té g é e s p a r 5 cm de p lo m b . L e s d iv e rs e s o p é ra tio n s son t e ffe c tu é e s avec d e s a p p a re ils sp é c ia le m e n t é tu d ié s p o u r la m a n ip u la tio n à d is ta n c e .

Figure 2

Schéma de l'installation complète.

N ous p ro p o so n s d ’u t i l i s e r t r o i s u n ité s de t r a v a i l r e l i é e s e n t r e e l le s p a r un co n v o y eu r. Il e s t p o ss ib le d ’in s ta l le r une u n ité ou deux, s i to u s le s ra d io é lé m e n ts c i té s n ’in té r e s s e n t p as l ’u t i l i s a te u r .

Il e s t p ré fé ra b le de g ro u p e r c e r ta in s ra d io é lé m e n ts en fonction de le u rs a f f in i té s . P a r e x e m p le , d a n s la p r e m iè r e b o îte d iv is é e en d eux z o n e s on p e u t p o s i t io n n e r le s d is p o s i t i f s :a) d ’in tro d u c tio n d e s p ro d u its i r r a d i é s (fig . 2 - 1 ),

d e d e s s e r t i s s a g e (fig . 2 - 2 ) ou de d é v is s a g e d e s c o n ta in e r s (fig . 2 - 4), le r é c ip ie n t d ’é v a c u a tio n d e s d é c h e ts s o lid e s (fig . 2 - 3 ) .

b) de p ré p a ra tio n d es ra d io é lé m e n ts sod iu m -2 4 , p o ta ss iu m -4 2 e t b ro m e-8 2 c o m p re n a n t le m a té r i e l su iv a n t:un a p p a r e i l d e d is s o lu tio n (fig . 2 - 1 1 ), un a g i ta te u r m a g n é tiq u e (fig . 2 - 1 2 ),


un p o r te - é l e c t r o d e av e c un r in c e - é le c t r o d e (fig . 2 - 8 e t f ig . 3), un r â t e l i e r de p ip e t te s e t un r in c e - p ip e t t e (fig . 2 - 1 0 ), un r é s e r v o i r à ea u d is t i l l é e (fig . 2 - 9 ), d e s a r r i v é e s de r é a c t i f s (fig . 2 - 7).

Figure 3

Porte-électrode avec rince-électrode.

D an s la s e c o n d e b o îte on p eu t in s t a l l e r d eu x d e s t r o i s e n s e m b le s de p r é p a ra t io n s u iv a n ts : c u iv re -6 4 , a r s e n ic - 7 6 , o r -1 9 8 c o l lo ïd a l .

A c e t e f fe t le m a té r i e l su iv a n t s e r a n é c e s s a i r e ,a) P o u r le c u iv re -6 4

un é ta u e t un e p in c e à d é v i s s e r (fig . 2 - 4),un p r é c ip i ta te u r ( f ig - 2 - 29),un f la c o n de d ilu tio n (fig . 2 - 14),u n e co lo n n e de r é s in e (fig . 2 - 16),un é v a p o r a te u r (fig . 2 - 17),t r o i s b o u le s à s ip h o n e r (fig . 2 - 1 3 ) ,d eu x p ip e t te s e t un r in c e - p ip e t t e .

60 M. DOUIS et J. VALADE

b) P o u r l ’a r s e n i c - 76u n é ta u e t u n e p in c e à d é v i s s e r (fig . 2 - 4 ),un p r é c ip i ta te u r (fig . 2 - 29),u n e c o lo n n e de r é s in e (fig . 2 - 16),un é v a p o r a te u r (fig . 2 - 1 7 ) ,d eu x b o u le s à s ip h o n n e r (fig . 2 - 13),deux p ip e t te s e t un r in c e - p ip e t t e .

c) P o u r l ’o r -1 9 8 c o llo ïd a lun é ta u e t u n e p in c e à d é v i s s e r (fig . 2 - 4 )„ un é v a p o r a te u r (fig . 2 - 18),un f la c o n av e c a g i ta t io n p a r p u ls a tio n ( fig .-2 - 2 0 ), d eux b o u le s à s ip h o n n e r (fig . 2 - 13), u n e b u r e t t e de 25 m l (fig . 2 - 2 1 ) .

D an s l a t r o i s iè m e b o îte d iv is é e en deux z o n e s , on p e u t in s t a l l e r :a) P o u r la p r é p a r a t io n du m e rc u re -1 9 7

un é ta u e t un e p in c e à d é v i s s e r (fig . 2 - 4 ), un a p p a r e i l d e d is s o lu tio n (fig . 2 - 1 1 ), un a g i ta te u r m a g n é tiq u e (fig . 2 - 1 2 ),un p o r te - é l e c t r o d e e t so n r in c e - é le c t r o d e (fig . 2 - 8 e t f ig . 3 ),un r â t e l i e r d e p ip e t te s e t un r in c e p ip e tte (fig . 2 - 1 0 ),un r é s e r v o i r d ’eau d is t i l l é e (fig . 2 - 9 ), d e s e n t r é e s de r é a c t i f s (fig . 2 - 7 ) .

b) P o u r la p r é p a ra t io n de l ’a n t im o in e -122, du m a n g a n è se -5 6 , de l ’o r-1 9 8 e t de l ’a r s e n i c - 77un é tau e t une p in c e à d é v i s s e r (fig . 2 - 4),un a p p a r e i l de d is s o lu tio n (fig . 2 - 1 1 ),un a g i ta te u r m ag n é tiq u e (fig . 2 - 1 2 ),un a p p a re i l de f i l t r a t io n (fig . 2 - 27),un r â t e l i e r de p ip e tte e t un r in c e -p ip e t te (fig . 2 - 1 0 ),un r é s e r v o i r d ’eau d is t i l lé e (fig . 2 - 9),une am p o u le à d é c a n te r (fig . 2 - 28),d e s e n t r é e s de r é a c t i f s (fig . 2 - 7).

D é ta ils du m a té r ie l u t i l is é

L e m a té r ie l u t i l i s é p o u r la r é a l is a t io n de c e t e n sem b le a é té s p é c ia le m e n t é tu d ié p o u r l ’é q u ip em e n t du nouveau la b o ra to i r e d es r a d io é lé m e n ts à S ac lay qu i e s t e n t ré en fo n c tio n n em e n t fin 1961.

Il s e r a i t fa s tid ie u x de d é c r i r e dans le d é ta il to u s le s a p p a re ils u ti l is é s ; l e s le c te u r s p eu v e n t s e r a p p o r te r au B u lle t in d ’in fo rm a tio n s s c ie n t if iq u e s e t te c h n iq u e s du C o m m is s a r ia t à l ’é n e rg ie a to m iq u e [4].

N ous d é c r i r o n s s im p le m e n t le s é lé m e n ts e s s e n t i e l s .

B o î t e é t a n c h e

L ’u n ité de t r a v a i l e s t la b o îte é ta n c h e . C ’e s t un p a ra llé lé p ip è d e a y a n t un e h a u te u r de 2 , une l a r g e u r de 0,9 m e t une lo n g u e u r de 2 m .

L ’o s s a tu r e e s t en p ro f ilé « o m ég a » en a c ie r soudé p e rm e tta n t de f ix e r d e s p an n e au x en « p le x ig la s s » d e 8 m m d ’é p a is s e u r p a r l ’in te r m é d ia i r e de


s e r r e - jo in t s . A 900 m m du so l, d e s c o r n iè re s su p p o rte n t un p lan de t r a v a i l en m a tiè re p la s tiq u e . L a b o îte e s t m un ie de ro u le tte s ; en p o sitio n défin itiv e e l le e s t s ta b il i s é e p a r d es v é r in s m é ca n iq u es .

Protection

D es p o te a u x d ’an g le en p lo m b , r e l i é s p a r d e s c o r n iè r e s m é ta l l iq u e s , s e rv e n t d ’in f r a s t r u c tu r e à l ’a s se m b la g e de b r iq u e s de p lom b à c h e v ro n s de10 cm s u r 10 e t 5 cm d ’é p a is s e u r . On pose ég a le m en t s u r c e s po taux un to it m é ta l l iq u e b lin d é . D es h u b lo ts d e v e r r e s au p lo m b , a in s i qu e d e s r o tu le s p o u r le p a s s a g e d es p in c e s à d is ta n c e v ien n en t s ’e n c a s t r e r dans le m u r s u r la fa c e de t r a v a i l .

Ventilation

a) V en tila tio n de la b o îte é tan ch eE lle e s t a s s u ré e p a r des tu rb in e s à m a rc h e continue (fig. 2 - 24), donnant

un ren o u v e lle m e n t d ’a i r de l ’o r d re de 50 fo is p a r h e u re avec une d é p re ss io n de 5 m m d ’eau .

E n t r e l a b o îte e t l a tu r b in e , n o u s d is p o s o n s d e s f i l t r e s (fig . 2 - 25).b) V e n ti la t io n de l a v e r r e r i e

D ans le s a p p a re ils d e s tin é s à des ra d io é lé m e n ts te ls que l ’o r - 198 co llo id a l, le c u iv re -6 4 , l ’a r s e n i c - 76, l a v e r r e r i e e s t r e l i é e à un e r a m p e à d é p r e s s io n p o u r r é d u ir e l a c o n ta m in a tio n de l ’in té r i e u r de la b o îte . Une d é - p re ss io n ^d e l ’o rd re de - 2 0 m m d ’eau e s t r é a l is é e p a r un b loc m o te u r d ’a s p ir a t e u r m é n a g e r (fig . 2 - 26). I l fa u t d is p o s e r u n p iè g e a p p r o p r ié e n t r e la v e r r e r i e e t l e m o te u r ( f ig - 2 - 23).

L ’e n s e m b le de ce m a té r i e l e s t p o sé s u r le to i t d e l ’e n c e in te .

Pupitres de commande

Il e s t ju d ic ie u x de s é p a r e r le s co m m an d e s é le c tr iq u e s d e s co m m an d es d ’eau ou de g a z . N ous p ro p o so n s d eux ty p e s de p u p itre : l ’un d ev a n t le m u r de p lom b à 70 cm du so l p o u r y in c o rp o re r le s in te r ru p te u r s , v oyan ts lu m ineux, r e la is , e t c . , l ’a u t re à 2 m du so l, to u jo u rs s u r le m u r de plom b, pour d is p o s e r le s c o m m a n d e s d e s f lu id e s liq u id e s e t g a z e u x e t p o u r e n c a s t r e r le s c a d ra n s .

Moyens d’accès

Nous p ro p o so n s deux a c c è s p a r l ’in te rm é d ia ire d’un sa s (fig- 2 - 6 e t 2 - 30), p u is un c o n v o y e u r à b an d e du type po ly v in y le - f ib r e s de v e r r e g l is s a n t s u r un ch em in de p la s tiq u e . Le m o te u r de ce co nvoyeu r se tro u v e à l ’e x té r ie u r so u s le s a s (fig . 2 - 30).

L a jonction e n tre deux b o îte s e s t r é a lis é e p a r un s a s de lia iso n ra c c o rd é p a r d es so u ffle ts en v iny le .

Осо

s

Figure 4

Appareil de dissolution.

Figure 5

Appareil de précipitation.

[. DOUIS

et J.

VA

LAD

E


Figu

re

6 Fi

gure

7

App

arei

l de

filtr

atio

n.

Eva

pora

teur

.


Figure 8

Vue d ’ensemble de l'installation montée.

Eclairage

Il se fa it p a r des tu b es f lu o re sc e n ts po sés s u r le to it de la bo îte étanche. A insi le changem ent de tube peut se fa ire sans o u v r ir l ’encein te .

Verrerie

P o u r le s d if fé re n ts ra d io é lé m e n ts c i té s , nous e s sa y o n s de s ta n d a rd is e r au m a x im u m la v e r r e r i e . V o ir l e s f ig u re s d e s a p p a r e i l s de d is s o lu t io n (fig . 4) de p ré c ip ita tio n (fig . 5), de f i l t r a t io n (fig . 6 ) e t d ’é v a p o ra tio n (fig . 7).

CONCLUSION

P o u r a v o ir une id é e co m p lè te de c e tte in s ta lla tio n , i l r e s te m a in te n an t à é v a lu e r l ’e n s e m b le du m a té r ie l . C e c i e s t r e la t iv e m e n t f a c i le c a r to u t le m a té r i e l c i té s e tro u v e en v e n te en F r a n c e d a n s l e s f i r m e s p r iv é e s .

P ro te c t io n (b r iq u e s de p lom b, p o teau x d ’a n g le s , to it) F 52 000B o îte s é ta n c h e s ( t ro i s b o îte s c o m p lè te s av ec s u r fa c e de t r a v a i l ) 27 000P in c e s e t r o tu le s de p a s s a g e (douze) 11 000H u b lo ts en v e r r e au p lo m b (s ix h u b lo ts de 240 m m de d ia m è tre ) 10 000P u p i t r e de co m m an d e 2 000V e n t ila tio n 5 000


E v a c u a tio n d e s d é c h e ts (p o u b e lle s en p lom b) 9 000D e s s e r t i s s e u s e 8 000C on v o y eu r 4 000M a té r ie l é le c tr iq u e 8 000V e r r e r i e 5 000D iv e rs 20 000

F 161000

L e p o id s de l ’in s ta l la t io n c o m p lè te e s t de 30 to n n e s . I l f a u d ra p r é v o ir une c h a rg e au so l c o r re sp o n d a n te , s i l ’on v eu t in s t a l l e r c e t e n se m b le dans un la b o ra to i r e (v o ir la vue d ’e n se m b le de l ’in s ta l la t io n m o n té e à la f ig . 8 ).

R É F É R E N C E S

[1] LAURENT, H. e t SIMONIN, P . , J. phys. e t du radium 14 (1953) 294-298.[2] DOUIS, M. e t VALADE, J. , Rapport CEA n°2072 (1961).[3] HENRY, R. , HERCZEG, C . e t FISHER, C . , Intern J. Appl. Radiation and Isotopes 2, 2 (1957) 136.[4] DOUIS, M ., Equipement du bâtim ent de production des radioélém ents, Bulletin d'informations scientifiques

e t techniques du CEA n°51 (1961).

D I S C U S S I O N

C. T A Y LO R : I w ould l ik e to a s k w hat p h a r m a c e u t ic a l c o n t ro ls youw ould re c o m m e n d on th e s e s h o r t- l iv e d is o to p e s . One fe e ls th e y shou ld be te s te d fo r s te r i l i ty , e t c . , and th is is a d ifficu lt p ro b lem b ecau se of the sh o r t t im e a v a ila b le . Do you re c o m m e n d c a r ry in g out su c h t e s t s on th e se s h o r t liv e d iso to p e s fo r m e d ic a l u se ?

M . DOUIS: R a d io iso to p e s in te n d ed fo r m e d ic a l u se shou ld , of c o u r s e , b e su b je c te d to p h a r m a c e u tic a l c o n tro ls , bu t w hen th e y h av e a v e r y s h o r t h a lf - l if e , a s in th e p r e s e n t c a s e , i t is c le a r ly no t p o s s ib le to t e s t th e m b io lo g ic a l ly , fo r in s ta n c e , b e fo re su pp ly ing th e m to th e u s e r s . T o o v e rc o m e th is d ifficu lty , a n u m b e r of t e s t s shou ld be c a r r i e d out b e fo re th e iso to p e s a r e f i r s t p la c e d on th e m a rk e t , fo r in s ta n c e c h e m ic a l t e s t s ( e .g . to d e t e r m in e th e v a le n c y of th e iso to p e ) , p h y s ic a l t e s t s (fo r th e h a l f - l i f e ) and b io lo g ic a l te s t s ( s te r i l i ty , ab sence of p y ro g en s , e tc . ) . Once a m a rk e tin g lic en c e h a s b ee n is s u e d by th e P h a r m a c e u t ic a l C o n tro l B o a rd , no c h a n g e s sh o u ld b e m a d e in th e m e th o d s o f p r e p a r a t io n o r in th e e q u ip m e n t. T h e ro u t in e ou tput shou ld th e n be s y s te m a tic a lly sa m p le d and th e s a m p le s te s te d w ithin a m a tte r of d ay s .

T h is i s th e p r o c e d u re we fo llow in th e R a d io is o to p e s D e p a r tm e n t a t S a c la y , and i t h a s no t p r e s e n te d u s w ith any d if f ic u lt ie s . T h e r e h a s b ee n no t ro u b le w ith iso to p e s su p p lied w ithou t a s t e r i l i t y t e s t .

THE PRODUCTION AND DISTRIBUTION OF SHORT-LIVED RADIOISOTOPES IN THE

UNITED KINGDOM

C. TAYLOR, R. WEST AND M. WHITING ATOMIC ENERGY RESEARCH ESTABLISHMENT, HARWELL, ENGLAND


THE PRODUCTION AND DISTRIBUTION OF SHORT-LIVED RADIOISOTOPES IN THE UNITED KINGDOM. M aterials irrad ia ted for short periods must be loaded and unloaded w hile the reacto r is operating . Devices are described for accom plish ing this with g raph ite -m odera ted (BEPO) and heavy -w ater m oderated (DIDO) reactors. Problems of nuclear h eating and reac tiv ity changes a re discussed.

A review is given o f the distribution o f short-lived radioisotopes produced in the research reactors a t Harwell. Table 1П shows the number of deliveries made during the past ten years and gives the distances over which they have been despatched.

PRODUCTION ET DISTRIBUTION DES RADIOISOTOPES A COURTE PÉRIODE DANS LE ROYAUME-UNI. Les matières irradiées pendant un bref laps de temps doivent être chargées e t déchargées pendant le fonctionne* ment du réacteur. Le m ém oire décrit des appareils perm ettant de pratiquer de telles irradiations dans un réacteur ralenti au graphite (BEPO) e t un réacteur ralenti à l’eau lourde (DIDO). On passe en revue'les problèmes d 'échauffem ent nucléaire e t de m odification de la réactiv ité .

On com m ente la distribution des radioisotopes â courte période produits dans les réacteurs de recherche de H arw ell. Le tab leau 111 indique le nom bre de livraisons effectuées au cours des dix dernières années e t les distances auxquelles les radioisotopes ont é té envoyés.

ПРОИЗВОДСТВО К0Р0ТК03И&У11ИХ ИЗОТОПОВ В СОЕДИНЕННОМ КОРОЛЕВСТВЕ И ИХ РАССЫЛКА. Отмечается, что облученные в течение короткого времени материалы следует загружать и разгружать во время работы реактора. Описываются приспособления, необходимые для выполнения этой работы на реакторе с графитовым замедлителем (ВЕРО) и тяхеловодном реакторе (DIDO). Обсуждаются проблемы ядерного наг рева и изменений реактивности.

Дается обзор рассьйпси короткоживущих изотопов, получаемых на исследовательских реакторах в Харуэлле. Приводятся данные о количестве поставок, произведенных в течение прошедших десяти лет* и расстояния, на которые производится рассылка.

PRODUCCIÓN Y DISTRIBUCION DE RADIOISOTOPOS DE PERÍODOCORTO EN EL REINO UNIDO. En la memoria se estudian la producción y distribución de radioisótopos de período corto en e l Reino Unido. Los m ateriales irradiados por períodos cortos deben cargarse y descargarse mientras e l reactor está funcionando. Se describen los dispositivos utilizados para llevar a cabo estas operaciones en los reactores moderados con grafito (BEPO) y con agua pesada (D ID O ). Se exam inan los problem as planteados por e l ca len tam ie n to nuclear y por las variaciones de reactiv idad .

Se expone la distribución de los radioisótopos de período corto producidos en los reactores de investigación de Harwell. En e l cuadro Ш se indica e l núm ero de entregas en los últim os d iez años y las distancias a que se han enviado los m ateriales.

S h o r t- l iv e d r a d io is o to p e s p r e s e n t th e p r o d u c e r w ith p ro b le m s a t th e r e a c to r , in th e p r o c e s s in g la b o ra to r y , and in d is t r ib u t io n . T h e f i r s t and th i r d of th e s e a r e d is c u s s e d in th i s p a p e r .

1. PRO D U C TIO N

Iso to p e p ro d u c tio n began a t H arw ell in S ep tem b er 1947, in the g ra p h ite m o d e ra te d r e a c to r G L E E P . S am ples w e re i r ra d ia te d in a .h o rizo n ta l channel

67

68 С . TAYLOR et al.

ru n n in g th ro u g h th e c e n tr e of th e r e a c to r c o re . T hey w e re h e ld in a t r a in of g ra p h ite b lo c k s w h ich cou ld b e p u sh e d out in to a tu n n e l- l ik e le a d sh ie ld m oun ted b e s id e th e r e a c to r . H andling tongs w e re u se d to t r a n s f e r sa m p le s f ro m th e t r a in to t r a n s p o r t c o n ta in e rs .

An im p ro v e d v e r s io n of th is a r ra n g e m e n t w as l a t e r u se d w ith th e m o re p o w e rfu l r e a c t o r B E P O w hen i t c a m e in to u s e in M a rc h 1949 (F ig . 1). A m a s s iv e sh ie ld in g tu n n e l w as m oun ted on a m oving p la tfo rm w hich cou ld be a lig n ed w ith any one of f iv e h o r iz o n ta l iso to p e c h a n n e ls , e a c h f i t te d w ith a t r a i n of g ra p h i te b lo c k s s im i la r to th o s e in G L E E P . In th is c a s e a fu lly - s h ie ld e d u n lo a d in g s ta t io n w as in c lu d e d a s p a r t of th e tu n n e l. S a m p le s to b e re m o v e d w e re b ro u g h t u n d e r th is s ta tio n , l if te d f ro m th e g ra p h ite t r a in by a i r su c tio n , and a llo w ed to f a l l th ro u g h a f le x ib le tu b e in to a t r a n s p o r t c o n ta in e r on th e f lo o r of th e r e a c to r h a ll.

F ig .l

Tunnel-type isotope unloading equipment originally installed at BEPO.The tunnel is aligned with the centremost of the five channels used for isotope production. The pipes beneath the unloader are for the reactor

control rods.

B oth th e s e in s ta l la t io n s w e re d es ig n ed to b e un loaded only when th e r e - a c to r w as n o t o p e ra tin g . A t th e t im e they w e re b u ilt th e dem and fo r r a d io is o to p e s w as m u c h s m a l le r th a n i t i s now, and cou ld b e m e t by w eek ly u n lo ad in g s done d u rin g th e r e g u la r r e a c to r shu t-dow n p e r io d s . As the dem and g rew i t b e c a m e c le a r th a t a d ev ice w hich could be un loaded a t any tim e w as

SHORT-LIVED RADIOISOTOPES IN THE UNITED KINGDOM 69

d e s i r a b le , e s p e c ia l ly fo r th e s h o r te r - l iv e d is o to p e s . A s w ell a s re d u c in g th e am ount of w ork to b e done du rin g th e sh o r t shut-dow n p e r io d s , and m aking p o s s ib le a b e t te r supp ly s e rv ic e to u s e r s , such a fa c ili ty w ould allow m uch b e t t e r u s e to b e m a d e of th e i r r a d ia t io n sp a c e in th e r e a c to r . F o r s h o r t l iv e d is o to p e s i t w ou ld a ls o r e d u c e th e p o s s ib i l i ty of b u ild in g up u n w an te d lo n g - l iv e d a c t iv i t ie s by u n n e c e s s a r i ly lo n g i r r a d ia t io n .

A sa m p le -c h a n g e r w o rk ing on th e e n d le s s b e lt p r in c ip le w as developed to m e e t th is n eed . It h a s been ou tstand ing ly su c c e ss fu l and h a s shown i ts e lf to b e a th o ro u g h ly s a t is f a c to ry w ay of m an ag in g an iso to p e p ro g ra m m e in a la r g e g ra p h ite -m o d e ra te d r e a c to r . F iv e of th e s e u n its have b ee n in s ta l le d in B E P O , r e p la c in g th e tu n n e l eq u ip m en t.

T h e g e n e ra l a r r a n g e m e n t of one of th e s e u n its i s show n in F ig . 2. T he b e l t , w h ich i s a f le x ib le ch a in of s a m p le h o ld e r s , p a s s e s r ig h t a c r o s s th e r e a c to r c o re in a 1 0 X 1 0 -c m s q u a re channel. I t h o ld s 300 sa m p le s in s ta n d a rd , 3 0 -cm 3a lu m in iu m c a n s , s e t a t 5 -c m sp a c in g . T he c a n s s ta n d v e r t i ca lly in th e b e lt se g m en ts , w hich a r e m ade up of g rap h ite cups in m a g n esiu m - z irc o n iu m su p p o rt b o x es w hich a lso ac t a s h inge p la te s link ing th e se g m en ts to g e th e r .

F ig .2

General arrangement of endless belt-type irradiation equipm ent now used in ВЕЮ.


T he o p e ra tin g head on th e p ile fac e c a r r i e s the w inding handle and d riv e m e c h a n ism fo r th e b e lt , to g e th e r w ith f a c i l i t i e s fo r lo ad in g , un lo ad in g and v iew in g (F ig . 3). Г is sh ie ld e d by 17 cm of le a d .

DRAWER SAMPLFSCONTROL

{ VIE' PERIF

Fig. 3

D etail of control head for belt-type irradiation equipment

A sa m p le i s lo a d ed by d ropp ing it in to a s lid in g d ra w e r and th e n m oving i t o v e r the se le c te d sa m p le h o ld e r, w hich h as p rev io u sly been wound out into the o p e ra tin g head . To un load one fo llow s th e r e v e r s e p ro c e d u re , the sam ple b e in g pushed up f ro m th e sa m p le h o ld e r w ith a p lu n g e r. It e n te r s the slid ing d ra w e r , w hich is th e n m oved o v e r to a d is c h a rg e p o r t lead in g down th ro u g h a flex ib le tube to a t r a n s p o r t co n ta in e r p laced on the f lo o r b es id e the re a c to r . A c tiv e s a m p le s a r e s o m e tim e s re lo a d e d in to th e r e a c to r by b low ing th e m p n eu m a tic a lly in to th e lo ad in g p o r t of a b e lt un it th ro u g h a s im ila r len g th of f lex ib le tub ing .

T h e se f le x ib le tu b e s a r e u n sh ie ld e d . A lthough m any sa m p le s ex ceed a c u r ie in a c tiv i ty a t th e t im e of un lo ad th is h a s no t b ee n found to c o n tr ib u te s ig n ific a n tly to th e d o se re c e iv e d by th e o p e r a to rs , b e c a u se th e t im e of e x p o s u re i s v e ry sh o r t.

If a s a m p le i s w ound d i r e c t ly f ro m th e c e n t r e of th e r e a c t o r in to th e o p e ra tin g h e a d , and u n lo a d e d , th e 2. 3 -m in A l28 a c tiv i ty of th e a lu m in iu m s a m p le c a n s w ill p r e s e n t an ad d ed sh ie ld in g p ro b le m . T h is a c tiv i ty m a y am ount to a m ax im um of 4 с of Al28 p e r can. It is u su a lly d ea lt with by w ind


ing a group of sa m p le s out into the b io lo g ica l sh ie ld of th e r e a c to r and allow ing th e m to cool off fo r a few m in u tes b e fo re b rin g in g them into the op era tin g h ead fo r unloading.

T he u til i ty of th e s e u n its i s w ell i l lu s t r a te d by th e e a s e w ith w hich they allow gold g r a in s fo r m e d ic a l u se to b e a c tiv a te d . T he a v e ra g e i r r a d ia t io n p e r io d fo r th e g ra in s is about fo u r h o u r s p e r sa m p le . By u s in g a b e l t u n it one can e a s ily ac tiv a te and d esp atch a se t of g ra in s on the sam e day an o rd e r i s r e c e iv e d , th e i r r a d ia t io n p e r io d b e in g ch o se n to g ive w h a te v e r a c tiv i ty th e u s e r r e q u i r e s . M o re th a n 10 000 b a tc h e s of g r a in s h a v e so f a r b ee n a c tiv a te d in th is w ay.

In la te 1957 th e h igh-flux r e a c to r DIDO b e c a m e o p e ra tio n a l at H arw ell, o ffe rin g a m ax im um th e rm a l flux of 1014 n c m -2 s - i . T h is m ay be co m p ared w ith 10^2n c m -2 s - i in B E P O and 2. 5X101° n cm -2 s - i in G L E E P . DIDO is a r e a c to r of the h e a v y -w a te r en ric h ed u ran iu m type, and the re la tiv e ly sm a ll s iz e of i t s c o re , in co m p a riso n to B E P O 's , m a k es it m uch m o re d ifficu lt to ex p lo it fo r iso to p e p ro d u c tio n . It w as f i r s t u se d fo r p ro d u c in g lo n g e r- liv e d iso to p e s in r ig s lo a d ed in to v e r t ic a l ch an n els p a s s in g c lo se to th e c o re , bu t th e s e r i g s w e r e of l i t t l e u s e f o r p ro d u c in g s h o r t - l iv e d m a t e r i a l s a s th e y c o u ld o n ly b e u n lo a d e d d u r in g sh u t-d o w n p e r io d s , w h ich a r e a t th r e e - w e e k in te r v a ls . It w as d ec id e d to in s ta l l a s a m p le c h a n g e r ana logous to a B E PO b e l t u n it in one of th e h o r iz o n ta l b e a m h o le s ex ten d in g th ro u g h th e g ra p h ite r e f le c to r up to the w all of the h e a v y -w a te r tank . U nlike BEPO , th e availab le channels in DIDO did not p a s s r ig h t th ro u g h the r e a c to r and so w ere not w ell s u ite d to a b e l t ty p e of e q u ip m en t. It w as h o w e v e r d e c id e d to a im fo r th e h ig h ly -fL ex ib le ty p e of s e r v ic e o b ta in e d w ith a b e l t u n it , and a ls o to m a k e th e fu l le s t p o s s ib le u s e of th e h ig h -flu x end of th e ch an n el. T he equ ipm en t w hich w as f in a lly evo lved i s show n in F ig . 4.

T h e u n it c o n s is ts of te n c y l in d r ic a l m a g a z in e s m oun ted one b eh in d th e o th e r on a c e n t r a l sh a f t. A k e y in g m e c h a n is m a llo w s th e m to b e r o ta te d independen tly . E ach m ag az in e h as seven c h a m b e rs to accom m odate s ta n d a rd 30-cm 3 iso to p e ca n s , and h a s an ad d itio n a l em p ty c h a m b e r w hich i s u se d to fo rm a s tra ig h t- th ro u g h t r a n s p o r t p a s sa g e . The ca n s lie h o rizo n ta lly . A fter a p p ro p r ia te a lig n m e n t of th e m a g a z in e s , by u s in g th e e x te r n a l c o n tro ls , a s a m p le i s b low n by c a rb o n d io x id e th ro u g h th e t r a n s p o r t p a s s a g e in to th e chosen ir ra d ia tio n position . It is subsequen tly re tu rn e d by the sam e p assag e fo r unloading.

On r e tu r n th e sa m p le i s held fo r a sh o r t t im e in the b io lo g ica l sh ie ld of th e r e a c to r to allow th e Al28 of th e can m a te r ia l to d ecay . F in a l d is c h a rg e i s dow nw ards th ro u g h a len g th of f lex ib le tube in to a - tra n s p o r t c o n ta in e r, as a t B E PO . As any a i r tr a p p e d in th e u n it w ould b u ild u p a s ig n ific an t am ount o f a rg o n -4 1 , th e w hole a s s e m b ly i s s e a le d and i s p u rg e d w ith C 0 2 b e fo re u s e . T h is i s v e n te d in to th e m a in r e a c to r p u rg e s y s te m .

F o u r of th e s e u n i ts h a v e now b e e n in s ta l l e d in DIDO. T h e i r h ig h e s t th e r m a l flu x , o c c u r r in g in th e m a g a z in e c lo s e s t to th e r e a c to r ta n k , i s 5 X 101 2 n c m _2s ■*. T h is i s r a th e r l e s s th a n o c c u rs e lse w h e re in the r e f le c to r , th e re d u c tio n b e in g due to n e u tro n a b so rp tio n in th e s t r u c tu re of th e sa m p le - changing m e ch a n ism .

N u c le a r h e a tin g in th is s t r u c tu re g iv e s r i s e to a m ax im um te m p e ra tu re of 135°C a t th e fo rw a rd sa m p le p o s itio n s , co m p ared to th e am b ien t g rap h ite r e f l e c to r t e m p e r a tu r e of 90°C. T h is m a k e s i t n e c e s s a r y to c o n s id e r th e


Fig. 4

M agazine-type irradiation equipm ent installed in DIDO

e ffe c ts of te m p e r a tu re upon so m e sa m p le m a te r ia ls . N u c le a r h ea tin g in th e s a m p le s th e m s e lv e s i s v e ry s lig h t and d o es no t s e t any l im it to th e am ount o f m a te r ia l th a t can b e i r r a d ia te d in a s ta n d a rd can .

W hile th e m a g a z in e u n its com bine a l l th e f e a tu re s e s s e n t ia l fo r a ra p id and eco n o m ic supp ly of s h o r t- l iv e d ra d io iso to p e s , so m e r i s k w as c e r ta in ly a c ce p te d in in s ta l l in g such com plex p ie c e s of m a c h in e ry in a re g io n of high n e u tro n flu x . If one of th e m sh o u ld f a i l i t cou ld b e r e p a i r e d on ly b y w ith d ra w in g th e w hole u n it f ro m th e r e a c to r and ta k in g i t to a l a r g e r e m o te - hand ling c e ll . In o v e r fo u r y e a r s continuous u se it h a s how ever b een n e c e s s a r y to r e m o v e on ly one ou t of th e fo u r u n its , th e r e m a in in g th r e e h av in g g iv en e x c e l le n t s e r v ic e .

T h e on ly c r i t i c i s m th a t can b e le v e lle d a g a in s t th e s e u n its i s th e i r in a b ility to ho ld m o re th a n one s a m p le a t a t im e in th e in te rm e d ia te p o s itio n p ro v id e d fo r A l28 d ecay . T h is slo w s down un loading , a s a coo ling p e r io d of se v e red m in u te s i s r e q u ir e d fo r each sa m p le .

V ery m uch h ig h e r f lu x es th a n can b e ob ta ined in th e m ag az in e u n its a r e a v a ila b le c lo s e r to th e r e a c to r c o r e , w h e re th e c e n tr a l flux r i s e s to about 10l4n c m -2 s - l . T he dem and fo r s h o r t- l iv e d i r r a d ia t io n s in th is re g io n of DIDO h a s how ever been slow to grow , and u n til re c e n tly w as h a rd ly su ffic ien t to ju s t ify th e u s e of one of th e e x p e n s iv e in - c o r e ch a n n e ls fo r th is p u rp o se a lo n e . A l im ite d s e rv ic e , fo r v e ry s m a ll s a m p le s only , h a s n e v e r th e le s s


b ee n m a in ta in e d by m ak in g u s e of th e 7. 5 -m m tu b e s th a t a r e f it te d to so m e of th e fu e l e le m e n ts , ru n n in g f ro m th e b a s e of th e e le m e n t up to th e to p of i t s sh ie ld p lug . T hey a r e c lo se d a t th e lo w e r end and d ip d i r e c t ly in to th e h ea v y w a te r in th e r e a c to r ta n k . T h e se "g u id e tu b e s " w e re o r ig in a lly in s ta l le d fo r m ak in g n eu tro n flux m e a s u re m e n ts in the c o re , and th e ir u se fo r iso to p e p ro d u c tio n i s so m e th in g of a m a k e - s h if t a r r a n g e m e n t . T h ey h av e h o w e v e r g iv en v e ry v a lu a b le s e rv ic e and th e e x p e r ie n c e g a in ed w ith th e m h a s b ee n u se fu l in d es ig n in g th e m o re s p e c ia liz e d eq u ip m en t now b e in g deve loped .

F o r i r r a d ia t io n s in a guide tu b e , sa m p le s a r e s e a le d in to s m a ll q u a r tz am p o u les m oun ted in a lum in ium h o ld e rs . A s tr in g of fo u r h o ld e rs is h inged to g e th e r w ith a lu m in iu m lin k s and a t ta c h e d th ro u g h a le n g th of a lu m in iu m c h a in to a s t e e l r o d w h ich p a s s e s th ro u g h th e to p b io lo g ic a l s h ie ld of th e r e a c to r .

T he g e n e ra l a r ra n g e m e n t of th e handling equ ipm ent fo r th e se ir ra d ia tio n s is show n in F ig . 5. A m in ia tu re le a d - s h ie ld e d c e ll i s p la c e d on th e r e a c to r to p p la te o v e r th e fu e l e le m e n t c a r r y in g th e s a m p le s , and th e s te e l ro d i s d ra w n up th ro u g h th e c e l l u n ti l th e to p of th e a lu m in iu m c h a in r e a c h e s a w inding d ru m . T h is i s in two p a r t s w hich ca n b e d r iv e n to g e th e r to fo rm a c la m p , g r ip p in g th e a lu m in iu m ch a in , th e to p of w h ich i s th e n s h e a r e d off f ro m th e end of th e sh ie ld ro d . T he ch a in i s now w ound onto th e d ru m u n til

Fig. 5

Handling equipm ent for high-flux irradiations in DIDO or PLUTO guide tubes *


th e sa m p le s have b ee n d raw n up in to th e r e a c to r top sh ie ld , w here they a re le f t fo r s e v e r a l m in u te s to allow so m e d ec ay of th e in e v ita b le Al28 a c tiv ity , w hich in th is c a s e am oun ts to a to ta l of about 60 c . T he cha in is nex t wound up u n til th e s a m p le s e n te r th e c e ll, w h ere th ey can be guided by two s im p le h an d lin g to n g s . A t th is s ta g e th e lo w e r e n try p o r t of th e c e ll i s c lo se d so th a t th e s a m p le s cannot fa ll b ac k in to th e r e a c to r . They a re then wound back off the d ru m and low ered one at a tim e in to a slid ing d raw er ca rry in g a s h e a r in g edge a t i t s u p p e r fa c e . W hen th e d ra w e r i s s lid out th e s h e a r c u ts th e lin k su p p o rtin g th e lo w e rm o s t sa m p le and it is f re e to d rop into a t r a n s p o r t c o n ta in e r p la c e d a g a in s t th e s id e of th e un it. A ll th e sa m p le s on one cha in m u s t b e un loaded a t th e sa m e tim e . R e load ing i s done by lo w e rin g a c o m p le te ly new s e t of sa m p le s in to th e h and ling c e ll.

N u c le a r h ea tin g [1, 2] in th e sa m p le s is se ldom tro u b le so m e in th e se i r r a d ia tio n s a s th e q u an titie s th a t can be i r ra d ia te d in each sam p le h o ld e r a re v e ry s m a ll (the u su a l vo lu m e of th e in n e r q u a r tz c a p su le is only 0 .1 5 cm 3). A t a r e a c to r p o w e r of 10MW th e r e a c to r g a m m a ra d ia tio n , w hich in m o s t

45 mm

ALUMINIUM GUIDE TUBE

ALUMINIUM SAMPLE HOLDER

SAMPLE 0.15 cm3

AIR GAP 0.75mm (diametral clearance 1.5mm)

9.5mm O.D.

7.0mm I.D .

Fig. 6

Conditions for heat transfer in guide-tube irradiation facility


s u b s ta n c e s i s th e p re d o m in a tin g s o u rc e of n u c le a r h e a t, g e n e r a te s abou t2. 5 W /g of m a te r i a l in a s a m p le i r r a d ia te d a t c o r e c e n tr e . T o th is m u s t be added a f u r th e r 3. 5 W g e n e ra te d in th e a lum in ium and q u a r tz of th e s a m p le h o ld e r. As sa m p le s se ldom exceed lg in w eight th e to ta l n u c lea r hea ting p e r sam p le i s th u s u su a lly le s s than 6W.

T h is am ount of h ea t can e a s ily b e conducted aw ay fro m the guide tu b e s , w hich dip d ir e c tly in to th e r e a c to r D2O and a r e r a te d to d is s ip a te 2 0 W /cm 2

of th e ir o u te r su rfa c e (Fig. 6 ), co rresp o n d in g to about 60W/cm of th e ir length, o r 300W p e r sam p le . H ow ever, hea t t r a n s f e r a c ro s s the a i r gap betw een the s a m p le h o ld e r and th é in s id e of th e gu ide tu b e m ig h t s t i l l b e a l im itin g f a c to r . E x p e r im e n ts h av e b e e n done a t H a rw e ll to m e a s u r e th is ; th e y show th a t a s m uch a s 20W can b e p a s s e d a c r o s s th is gap w ithout r a is in g th e te m p e r a tu re of th e sa m p le h o ld e r above 350°C. So f a r , no th e rm a l d am age h as b een o b se rv e d in any sam p le .

T h is type of fa c ility is now being u se d to the l im it of i t s cap ac ity . Only one guide is f itte d to each fu e l e lem en t, and th o se in the h ig h est f lu x es, n e a r th e c e n tr e of th e c o re , a r e in c o n s ta n t dem and . A c lu s te r of s ix tu b e s h a s r e c e n tly b ee n in s ta l le d in a hollow fu e l e lem e n t, bu t a s th e n u m b e r of s a m p le s to b e hand led b ec o m e s g r e a te r th e lim ita tio n s of the handling equipm ent b ec o m e in c re a s in g ly a p p a re n t. It i s p a r t ic u la r ly in a d eq u a te fo r rra n a g in g s h o r t - t e r m i r r a d ia t io n s , a s a s in g le s a m p le ca n n o t b e r e c o v e r e d w ith o u t b re a k in g up th e w hole s t r in g of w hich i t f o rm s a p a r t . T he u s e of a s in g le g u id e tu b e f o r a s in g le s a m p le w ould of c o u r s e b e f e a s ib le , b u t w a s te fu l .

New eq u ip m en t i s u n d e r d e s ig n to c a te r fo r th e i r r a d ia t io n of up to 72 s a m p le s , s im u lta n e o u s ly , any o r a l l of th e m b e in g re m o v a b le a t any t im e . Som e of th e f a c to r s to b e c o n s id e re d m ay. b e of in te r e s t .

T he eq u ip m en t w ill f i t in to th e 5 0 -m m d ia m . a x ia l ho le in a ho llow fu e l e le m e n t, and w ill b e w o rk e d p n e u m a tic a lly . In s id e th e f i s s i l e p a r t o f th e fu e l e le m e n t w ill b e a c l u s te r of s ix s a m p le tu b e s , e a c h of 1 1 -m m in s id e d i a m . , e a c h h o ld in g tw e lv e s a m p le s . T h e s a m p le s w ill n o t b e l in k e d t o g e th e r .

A bove th e c lu s te r i s a s e le c to r m e c h a n ism w hich c o n n e c ts any sa m p le tube to a p ipe le a d in g to a s to ra g e s ta tio n lo c a te d u n d e r th e top sh ie ld of th e r e a c to r . A ll th e s a m p le s in th e tu b e w ill b e b low n o u t to g e th e r in to th i s s to re , w h e re th e y w ill b e h e ld fo r th e Al28 a c tiv ity to decay . T hey w ill th en b e so r te d and sa m p le s re m o v e d as r e q u ire d . A fte r new sa m p le s have been added th e w hole b a tc h w ill b e blow n b ack in to th e r e a c to r .

The la r g e r d ia m e te r of the guide tu b es in th is fa c ility w ill allow sam p les up to 3 cm 3 to be i r ra d ia te d , p ro v id ed th ey can be con tained d ire c tly in a lu m in ium c a r r i e r s , o r up to 1 cm 3 if an in n e r q u a r tz cap su le is re q u ire d . Nuc le a r h e a tin g m ay be a l im it in g f a c to r in s a m p le s of th e s e s iz e s . A m a x im u m t e m p e r a tu r e of 300°C a t th e s u r f a c e of any s a m p le h o ld e r h a s b e e n ta k e n f o r th e d e s ig n s tu d y , a lthough th is i s n o t n e c e s s a r i ly an u p p e r l im i t f o r p i le s a fe ty , o r in d e e d f o r s a m p le s a fe ty . T h e d ia m e t r ic a l c l e a r a n c e b e tw e e n gu ide tu b e and s a m p le h o ld e r i s ta k e n to b e 0 . 8 m m , an d i t i s a s su m e d th a t th e a i r in th e sy s te m is r e p la c e d by h e liu m in o r d e r to im p ro v e h e a t t r a n s f e r . I t h a s b e e n show n th a t u n d e r th e s e c o n d itio n s a s m u c h a s 160W m a y b e d is s ip a te d w ith o u t e x c e e d in g th e d e s ig n t e m p e r a t u r e . T h e s a m p le h o ld e r and q u a r tz am pou le w ould c o n tr ib u te about 15W to w a rd s th is , le a v in g 145W fo r th e sa m p le m a te r ia l .


TABLE I

N U C LEA R H EATIN G IN CYLINDRICAL SA M PLES IRRADIATED AT CORE C EN TR E IN DIDO

S am ple s iz e 20X 8-m m d iam .S am ple vo lum e: 1 cm 3

R e a c to r p o w er : 10 MW

Samplem ateria l

Heating(W)

Samplem ateria l

Heating(W)

Alum inium 7 Nickel 24

Antimony 17 Platinum 60

Bismuth ' 25 Silicon 6

Calcium 4 Sodium ' 2 .5

Chromium 18 Tin 16

Iron 20 Tungsten 70

T ab le I show s th e ca lc u la te d n u c le a r h ea tin g in a nu m b er of ty p ic a l ta rg e t m a te r i a l s w hen i r r a d ia te d a t DIDO c o re c e n tr e , th e s a m p le v o lu m e b e in g ta k e n a s 1 c m 3. In m o s t c a s e s th e h e a tin g i s w e ll b e lo w th e d e s ig n l im i t , bu t th e u se of a s ta t ic h e liu m a tm o sp h e re , w hich im p ro v e s the h ea t t r a n s f e r f iv e -fo ld co m p ared to a i r , is ev iden tly w orth w hile .

A n o th e r f a c to r w h ich m ay l im i t th e c a p a c ity of th is u n it i s th e su d d en change in r e a c t iv i ty w hich o c c u rs w hen a s t r in g of sa m p le s is blow n out of th e r e a c to r in to th e s to ra g e s ta tio n . A m ax im u m of +0 . 1% d k /k i s allow ed fo r su c h ch a n g e s , and i t can b e show n th a t fo r a s t r in g of tw e lv e id e n tic a l s a m p le s th is c o r r e s p o n d s to a m a x im u m a b s o rp tio n a r e a p e r s a m p le of0 . 2 cm?, if th e eq u ip m en t i s lo c a te d in a fu e l e lem e n t n e a r th e c e n tre of th e

TABLE II

TO TA L ABSORPTIO N CROSS-SECTION F O R TH ER M A L NEUTRONS O F 1 -c m 3 SAM PLES

Samplem ateria l

(c m 2)Samplem ateria l

(cm 2)

Aluminium 0.014 Nickel 0.42

Antimony 0.18 Platinum 0.58

Bismuth 0.001 Silicon 0.01

C alcium 0.01 Sodium 0.01

Chromium 0.24 Tin 0.02

Iron 0.21 Tungsten 1.2


TABLE u i

D ELIV ER Y O F SH O R T-LIV ED RADIOISOTOPES PRODUCED IN H A R W ELL REA CTO RS 1951-61 , SHOWING DISTANCES

FRO M H A RW ELL TO USER

Radioisotope

H alf-life

(h)

No. of samples delivered in

United Kingdom

No. of samples delivered overseas

0-100 km 101-700 km 0-1000 km 1001-5000 km >5000 km

Cl38 0 .5 10 2 2 - -

. A41 2.0 45 19 22 3 -

Dy165 2 .3 25 - 1 1 -

Mn56 2.6 102 2 10 - -

Si31 2.6 240 6 6 4 1

K r85 4 .4 . 5 4 1 5 -

K42 12 .5 3800 1680 650 200 30

C u64 13.0 875 285 44 5 3

G a71 14.1 148 5 5 - -

Na24 15.0 4650 1320 1200 240 120

Р г14г 19.2 20 1 7 4 8

As76 26 .5 110 99 87 4 3

Ho166 27 .0 17 - 1 4 1

Br82 36.0 2445 432 264 160 13

La140 4 0 .2 170 43 48 9 -

Sm153 46 .2 23 3 4 13 2

Y “ 64.2 1212 648 240 312 168

A u198 64.8 6044 1962 2428 748 621

c o re , o r 0. 5 c m 2 i f i t i s n e a r th e c o re b o u n d a ry . T a b le II show s th e to ta l a b s o rp tio n a r e a s fo r a n u m b e r of 1 c m 3 s a m p le s . F o r so m e m a te r i a l s i t is w ell above 0 . 2 cm 2, and th e am ount ir ra d ia te d would have to be r e s t r ic te d to l e s s th a n 1 cmS. A lte rn a tiv e ly , if th e r e i s good r e a s o n fo r i r r a d ia t in g a fu ll am p o u le of su c h a m a te r ia l , a d e ta ile d c a lc u la t io n m a y b e m a d e of th e r e a c tiv i ty change due to a ll 1 2 s a m p le s , u s in g a p p ro p r ia te w eighting f a c to rs f o r e a c h s a m p le p o s it io n . In m a n y c a s e s i t w ill b e found th a t t h e r e a r e enough lo w -a b so rp tio n sa m p le s in th e b a tch to allow a t le a s t one la rg e sam p le of h igh c r o s s - s e c t io n to be i r ra d ia te d w ith safe ty .

2. DISTRIBUTION

D u rin g th e p a s t te n y e a r s o v e r 34 000 s a m p le s of s h o r t - l iv e d r a d io iso to p e s (h a lf - life l e s s th a n th r e e d ay s) h av e b ee n d esp a tc h e d d ir e c tly f ro m


th e H arw e ll r e a c to r s to u s e r s in o th e r la b o ra to r ie s (T ab le III). E ig h t th o u sand of th e s e w e re se n t o v e rs e a s . In addition , a la rg e nu m b er of d e l iv e r ie s of p ro c e s s e d iso to p e s of sh o r t life have been m ade th rough o u r rad io c h em ica l la b o ra to r ie s a t A m ersh am ,

G old-198 (65 h) and so d iu m -2 4 (15 h) a r e am ong th e iso to p e s th a t have b een supp lied f ro m H arw ell to A u s tra lia . T h ese iso to p es s e rv e to i l lu s tr a te th e f a c to r s a f fe c tin g th e lo n g - d is ta n c e d e l iv e r y of s h o r t - l iv e d m a te r i a l s . In both c a s e s qu ite a m o d e ra te n eu tro n flux w ill p ro d u ce a sa tu ra tio n ac tiv ity m an y t im e s g r e a te r th a n is u su a lly r e q u ir e d , and i t i s p o s s ib le to d e sp a tc h th e sa m p le w ith enough e x tra ac tiv ity to m ake up fo r th a t lo s t by decay d u ring th e jo u rn e y . W h e th e r th i s i s in f a c t p r a c t ic a b le d ep e n d s on th e r a d ia t io n e n e rg y of th e iso to p e , a s th is d e te rm in e s th e e x t r a w eigh t of sh ie ld in g r e q u ire d in th e t r a n s p o r t c o n ta in e r . If a 10 0 -m c b a tc h of Au198 i s d esp a tc h ed a t 400 m e , in o r d e r to co m p en sa te fo r d ecay o v e r tw o h a l f - l iv e s , th e a d d itio n a l w eigh t of th e th ic k e r sh ie ld in g c o n ta in e r w ould b e about 1. 5 kg. T he c o r re s p o n d in g f ig u re f o r N a 24 i s a lm o s t 100 kg , m a k in g i t u n e c o n o m ic to sh ip th is iso to p e o v e r s e a s ex c ep t in v e ry s m a ll q u a n titie s . M any c u r ie s of Au198 a r e how ever d e liv e re d r e g u la r ly o v er g re a t d is ta n c e s , a t qu ite m o d e ra te co s t.

At H arw ell, s a m p le s a r e r e g u la r ly un loaded fro m the r e a c to r , packed, and s ta r te d on th e i r jo u rn ey in l e s s th an 45 m in . T he n e a r e s t in te rn a tio n a l a i rp o r t can b e re a c h e d by ro a d in a f u r th e r 90 m in . An u n n e c e s s a ry delay , fro m th e p r o d u c e r 1 s po in t of view , is th e a ir l in e ru lin g th a t an iso tope p ac k age m u s t b e a t th e a i r p o r t a t l e a s t 90 m in b e fo re th e a i r c r a f t le a v e s . A no th e r h o u r sh o u ld b e a llo w ed fo r c le a r in g th e p a c k a g e th ro u g h c u s to m s a t th e a i r p o r t of a r r iv a l , and a f u r th e r h o u r f o r d e l iv e r in g i t to th e u s e r . In a ll, about s ix h o u rs of th e jo u rn ey m u s t be sp en t on th e ground . At p re s e n t fligh t sp e ed s th is i s eq u iv a len t to an a i r jo u rn ey of 5000 km : th u s fo r f lig h ts up to th is d is ta n c e th e package spends as m uch tim e on th e ground a s i t does in th e a i r , and th e a c tu a l f ly in g d is ta n c e f ro m p r o d u c e r to u s e r i s n o t of m u c h s ig n if ic a n c e .

R E F E R E N C E S

[1] ANDERSON, A.R. and WAITE, R .J . . Energy Absorption from Reactor Radiation in the heavy-water moderated Reactors DIDO and PLUTO, AERE Rep. C/R 2713 (1961).

[2] CONNOLLY, J.W . and NICHOLSON, K .P . . Energy Absorption by Materials exposed to Radiation in HIFAR, AAEC Rep. TM 109 (1961).

D I S C U S S I O N

K. HEYDORN: I w ould lik e to a sk w h e th e r you ex p ec t any p ro b le m sw ith r e s p e c t to th e re a c tiv ity when you blow out sa m p le s lo ca ted in the ce n tre of a fuel e lem en t d u rin g r e a c to r opera tion .

C. TAYLOR: We a r e n o t y e t u sin g a pn eu m atic sy s te m to m ove s a m p le s in a r e g io n w h e re r e a c t iv i ty e f fe c ts cou ld be im p o r ta n t . T h e e f fe c ts ex p e c ted w hen w e in s ta l l o u r new p n eu m atic s y s te m in DIDO a r e d is c u s s e d in th e p a p e r : i t w ill b e n e c e s s a r y to s e t a l im i t to th e a b s o rp tio n c r o s s - s e c t io n of e a c h b a tc h o f s a m p le s , b u t th is l im ita t io n w ill n o t b e o n e ro u s .


T h e m a in d ifficu lty in b low ing out sa m p le s f ro m th e c o re a r i s e s if one u s e s a lu m in iu m f o r th e c a p s u le , a s one th e n g e ts a t e r r i f i c b u r s t o f r a d ia t io n f ro m th e s o r t in g s ta tio n . We sh a ll no doubt h av e to change o v e r to a m a g n e s iu m a llo y w h ich w ill g ive so m e f ifty t im e s l e s s t ro u b le in th i s r e s p e c t .

L . G. STANG: Do you find th a t im p u r i t ie s in th e a lu m in iu m you u sea s c o n ta in e r and s t r u c tu r a l m a te r ia l g ive r i s e to o b je c tio n a b le a m o u n ts of a c t iv i ty — v ia th e (n,-y) r e a c tio n ?

C. TAYLOR: No, we u se h ig h -p u rity a lum in ium and do not get tro u b leof th a t s o r t , w ith th e p o ss ib le excep tion of sodium con tam ination .

L . G. STANG: We h av e in fa c t found a t B ro o k h av en th a t w e g e t N a i4

a s a com m on con tam inan t on a g re a t m any th in g s th a t a r e ir ra d ia te d . T h ere a r e p re su m a b ly two re a s o n s fo r th is : (1) th e NaCl in th e p e rsp ira tio n on the h ands w hich have h e ld th e ta rg e t p r io r to i r ra d ia tio n ; and (2) N aCl p a r t ic le s in th e a i r , a r i s i n g f ro m th e o c e a n w h ich i s o n ly ab o u t e ig h t m i l e s aw ay .

R. TO LM IE: Do you m ake r e g u la r u se of co b a lt w ire o r so m e o th e rta g to d e te rm in e th e in te g ra te d n e u tro n flux?

C. TAYLOR: Y es. We in c lu d e a sm a ll p ie ce of coba lt w ire in ev e rysa m p le h o ld e r u se d fo r o u r h ig h -flu x i r ra d ia t io n s .

W. GEBAUHR: A re t h e r e any r e s u l t s sh o w in g th e n e u tro n e n e rg yd is t r ib u t io n o f th e flu x f o r n , p r e a c t io n s , e tc . ?

C. TAYLOR: We have no such r e s u l t s . In p ra c t ic e it does not se e mn e c e s s a r y to know th e s p e c tr u m in d e ta i l . We e x p r e s s o u r f a s t f lu x e s in t e r m s of an "e q u iv a len t f is s io n flux", sp ec ify in g th e th re sh o ld d e te c to r Used and th e c r o s s - s e c t io n a ssu m ed .

P . TEM PU S: In T a b le I you h av e g iven f ig u re s f o r s a m p le v o lu m e sof 1 cm 1, Is th is sa m p le in so lid b lock fo rm , o r is i t a pow der? I th ink th is h a s so m e e f fe c t on th e h e a t t r a n s f e r f ro m th e s a m p le to th e tu b e s and th e r e a c to r .

C. TAYLOR: T he f ig u re s app ly to w h a te v e r fo rm w as th e m o s t conv e n ie n t fo r g e ttin g th e s u b s ta n c e in to th e v o lu m e of 1 c m 3 — it w ou ld b e a p o w d e r in m a n y c a s e s . W e h a v e n o t c o n s id e r e d th e h e a t t r a n s f e r in s id e th e sa m p le i ts e lf ; we ju s t c a lc u la te d th e te m p e r a tu re r i s e in th e a lum in ium sa m p le c a r r i e r . In s id e th e c a r r i e r i s th e q u a r tz , w h ich w ill b e a t a m uch h ig h e r t e m p e r a t u r e th a n th e a lu m in iu m , and in s id e th e q u a r tz t h e r e i s a sa m p le , w hich w ill be at a s t i l l h ig h e r te m p e r a tu re . T he r e a s o n fo r th e s e c a lc u la t io n s , h o w ev e r, i s p r im a r i l y one of r e a c to r sa fe ty . It i s a s s u m e d th a t if th e a lum in ium ho lds, i t does not m a tte r w hat happens to the sam p le — if i t m e lts o r if any o th e r such u n d e s ira b le e ffec t o c c u rs , th a t sp e lls tro u b le f o r th e iso to p e m an , not fo r the r e a c to r m an.

L . G. STANG: W ell, in th i s c o n n e c tio n I th in k a t te n t io n sh o u ld b ec a l le d to th e f a c t th a t in th e c a s e of t a r g e t s m a d e f ro m m a te r i a l o f h ig h c r o s s - s e c t io n , e . g . L i6 o r L i6Mg a lloy , th e sa m p le g e o m e try i s im p o rta n t and i t i s n e c e s s a r y to u se a v e ry th in fo il in o r d e r to avoid in te rn a l flux d e p r e s s io n w ith in th e sa m p le . T h e r e f o r e in su c h a case , i t i s im p o r ta n t th a t th e s a m p le d o e s n o t m e lt dow n in to a sh a p e o th e r th a n th a t o f a th in fo il .

C. TAYLOR: A g reed . T h e re m ay b e a sa fe ty p ro b le m too w ith th ism a te r ia l , a s w hen i t i s m e lte d i t r e a c t s w ith q u a r tz and so m a y r u p tu r e a q u a r tz c a p su le in te n d e d to c o n ta in it.

P . T E M PU S : D id you m a k e any p r a c t i c a l h e a t - t r a n s f e r m e a s u r e m e n ts d u r in g i r r a d ia t io n s in th e DIDO r e a c to r ?

80<

С . TAYLOR et al.

C. TAYLOR: No h e a t - t r a n s f e r m e a s u re m e n ts w e re m ad e d u rin g i r r a d ia tio n s , b u t th e a s se m b ly show n in F ig . 4, w hich w as b u ilt in th e la b o ra to r y , h a s b ee n ru n w ith d if fe re n t am oun ts of p o w er fed e le c t r ic a l ly in to th e s a m p le s , and a s tu d y h a s b e e n m a d e o f th e t e m p e r a t u r e s r e a c h e d on th e q u a r tz and on th e a lum in ium u n d er th e se cond itions. We do not th ink it h e lp fu l to s tudy th is in s id e th e r e a c to r b e c a u se although th e n u c le a r h ea tin g can b e q u ite e a s i ly c a lc u la te d , th e a c tu a l t e m p e r a tu r e r i s e d e p e n d s on m a n y f a c to r s and i t i s b e s t to m e a s u r e i t e x p e r im e n ta l ly .

P . A L B E R T : I w ould l ik e to go b a c k to th e q u e s tio n of th e so d iu min th e a lu m in iu m . Did you m e a s u re th e sod ium in y o u r a lum in ium i r r a d i a tio n tu b e s?

C. TA YLO R: Y e s , b u t I can n o t g ive an e x a c t a n s w e r a s I h av e no tgot th e la te s t f ig u re s on th is . I had v a r io u s p ie c e s of a lum in ium ir ra d ia te d , so m e w ra p p e d in c a d m iu m and so m e no t, in o r d e r to s e e i f i t w as a f a s t - n e u tro n r e a c tio n o r a s lo w -n e u tro n re a c tio n ; I found r a th e r to m y s u r p r i s e th a t in B E P O (the r e a c to r I w as w o rk in g w ith) p ra c t ic a l ly no Na24 w as p r o d u c e d in th e s a m p le e n c lo s e d in c a d m iu m . In o th e r w o rd s , i t i s l a r g e ly so d iu m im p u r i ty w h ich i s g iv in g th e t r o u b le .

P . A L B ER T: I am r a th e r s u r p r i s e d . I have w orked q u ite a lo t w itha lu m in iu m , e s p e c ia l ly p u r e a lu m in iu m , of w h ich th e so d iu m c o n te n t w a s d e f in ite ly l e s s th a n about 4 ppm . If you i r r a d ia te a lu m in iu m , fo r in s ta n c e in B E P O , you w ill g e t a so d iu m a c tiv ity c o r re s p o n d in g to abou t 80 ppm of sod ium (by c o m p a riso n w ith a sod ium sa m p le i r r a d ia te d fo r th e sa m e tim e ) . F o r a 2 5 -g tu b e you th u s h av e a sod ium a c tiv ity c o rre sp o n d in g to th e i r r a d ia tio n of 1. 5 -2 m g of so d iu m . T h is a c tiv i ty i s due to th e (n, a) r e a c t io n .

We have s tu d ied th e p ro d u c tio n of Na24 th ro u g h th e Al*' (n, a) N a24 r e a c tio n u s in g p u re a lu m in iu m co n ta in in g l e s s th a n 0. 2 ppm of N a. We found a m a rk e d e ffe c t d ep en d in g on w h e re a b o u ts in th e r e a c to r i r r a d ia t io n ta k e s p la c e : th e r a te of p ro d u c tio n d e c r e a s e s u n ifo rm ly a s th e d is ta n c e f ro m th e r e a c to r c o re is in c re a se d . In th e ax ia l channel of ZOE (F o n ten ay -au x -R o ses, F r a n c e ) , th e q u a n tity of N a 24 p ro d u c e d b y (n, a ) i s su c h th a t th e a c t iv i ty m e a su re d fo r 1 g of alum in ium is equ ivalen t to th a t fo r 60 ¡¿g of n a tu ra l so d iu m i r r a d ia te d in th e s a m e p o s itio n . On th e o th e r hand , in a g iven p o s itio n w ith in th e g ra p h ite r e f le c to r , th e N a24 ac tiv ity w ill be equ ivalen t to le s s than0 . 2 ppm of n a tu ra l sod ium .

C. TAYLOR: We n o tic e d th a t th e N a24 a c tiv i ty p ro d u c e d in s a m p le sof a lu m in iu m of id e n t ic a l w eig h t m a y d if fe r c o n s id e ra b ly , p ro b a b ly ow ing to a v a r ia b le co n tam in a tio n w ith N a123. We checked by ir ra d ia t in g alum inium s a m p le s w ra p p ed in cad m iu m and found th a t th e N a2 3(n, 7 ) N a24 r e a c tio n can c o n tr ib u te a s m u c h a c t iv i ty a s th e A l21 (n, a) N a 24 r e a c t io n , b u t th a t th e am o u n t v a r i e s f ro m s a m p le to s a m p le . A s M r . A lb e r t p o in ts o u t, p u r e a lu m in iu m w ould no t b e e x p e c ted to c o n ta in enough so d iu m to g ive th is r e s u l t , and M r. S ta n g 's s u g g e s tio n th a t p e r s p i r a t io n f ro m th e f in g e r s c a n c a u se co n tam in a tio n w ith sod ium m ay w ell be th e exp lana tion . We have not looked a t th is p ro b le m fo r s e v e ra l y e a r s , bu t w ill ta k e it up again .

P . A L B E R T : I th in k i t m u s t b e a q u e s tio n of c h o o s in g th e p r o p e ra lu m in iu m q u a lity .

B . R IB E R P E T E R S E N : H ave you i r r a d ia te d o rg a n ic s u b s ta n c e s iny o u r q u a r tz am p o u les and, if so , w hat p r e s s u r e r i s e do you allow in th e m ?


C. TAYLOR: I t i s d if fic u lt to know w hat p r e s s u r e one h a s got in th eam p o u les and we have a lo t of a rg u m e n t about w hat we can i r r a d ia te in th em . W e h av e a c h e m is t who h a s s tu d ie d th is , and he d e c id e s w hat w e c a n i r r a d ia te . I b e l ie v e h e t r i e s to c a lc u la te w hat th e p r e s s u r e w ill b e , and i f th e e s t im a te d p r e s s u r e r i s e i s m o re th a n 5 a tm h e s a y s we m u s t no t i r r a d ia te . H ow ever, he tíim se lf h a s po in ted out th a t th e re is a g re a t la ck of in fo rm ation in th is f ie ld : one g e ts d is s o c ia tio n of th e s e s u b s ta n c e s f ro m th e e p i th e rm a l n eu tro n ra n g e , and th e re is not enough in fo rm atio n av a ilab le a b o u t 'th e 'sp e c tru m in th a t ra n g e .

B . R IB E R P E T E R S E N : H ave you m a d e any e x p e r im e n ta l c h e c k s onth e s tr e n g th of th e am p o u les?

C. TAYLOR: I have not m ade any e x p e r im e n ta l ch e ck s . I know th a tsom ebody a t H a rw e ll h a s b ee n i r r a d ia t in g a i r s a m p le s a t 50 a tm and m o r e in q u a r tz am pou les of 1 cm a w ithout g e tting any b re a k a g e s . I have not h e a rd of any t ro u b le w ith s a m p le s w hich w e re c a lc u la te d to g ive l e s s th a n 5 a tm .

I w ould l ik e to m a k e a g e n e ra l co m m en t a t th is p o in t. In sw im m in g - p o o l r e a c t o r s one m a y e i th e r s e a l th e in d iv id u a l s a m p le s c o m p le te ly an d h an d le th e m in d iv id u a lly in th e w a te r of th e poo l, o r one m a y u s e s a m p le s c lo s e d on ly b y s c r e w - c a p s and i r r a d i a t e th e m in l a r g e r w a te r -p r o o f c a r t r id g e s lo w e re d in to th e r e a c to r p oo l. T h e se c o n d m e th o d i s q u ite s a t i s fa c to ry if only a few ir r a d ia t io n s a r e to b e hand led , bu t i t b ec o m e s v e ry in conven ien t when m any s h o r t-p e r io d i r ra d ia t io n s m u st be done. I would su g g e s t, on th e b a s is of m y ex p e rien c e , th a t th e tim e sp en t in develop ing f a c i l i t i e s fo r se a lin g c a p su le s p ro p e r ly and fo r hand ling th e m u n d e r w a te r is w ell w o rth w h ile and th a t i t w ill b e r e p a id by th e tim e sa v ed l a te r d u r in g o p e r a t io n s .

B . R IB ER P ET E R S E N : We have m ad e am p o u les a l i t t l e b ig g e r th a ny o u rs , w ith a w all th ic k n e s s of about one m il l im e tr e ; w e t r i e d about 1 0 0 of th e m fo r s tre n g th , and th e y exp loded b e tw een 20 a tm and, I th in k , 160 a tm .

M. DOUIS: Som e u s e r s of ra d io iso to p e s would like to i r ra d ia te chem ic a l com pounds in so lu tio n , b u t th e r e a c to r p eo p le do n o t lik e i t . C ould we h a v e th e v ie w of H a rw e ll a s to th e i r r a d i a t i o n o f c o m p o u n d s in so lu t io n ?

C. TAYLOR: We find in p a r t ic u la r th a t we g e t r e q u e s ts f ro m peop lewho w ant to do ac tiv a tio n a n a ly s is , and who w ould lik e to i r r a d ia te so lu tio n s co n ta in in g v e ry s m a ll q u a n titie s . E a c h of th e s e p r o p o s a ls is su b m itte d to o u r r e a c to r c h e m is t fo r h is opinion. I th ink I am r ig h t in say in g th a t aqueous so lu tio n s con tain ing v e ry sm a ll am ounts of o rd in a ry su b stan ce s m ay be i r r a d ia te d p ro v id e d th e c a lc u la tio n show s th a t th e p r e s s u r e w ill no t r i s e above5 a tm w hen th ey a r e seeded in to a q u a r tz am poule. We have e s ta b lish e d a l i s t of th e q u an titie s and co n c e n tra tio n s accep tab le fo r ir ra d ia tio n , but a r e alw ays p re p a re d to S tre tc h th e p o in t if th e re i s good re a s o n fo r doing so . I m y se lf am co n v in ce d th a t th e le v e ls co u ld b e r a i s e d and th a t m a n y m o r e s a m p le s cou ld a c tu a lly be a c c e p te d . I t w ould b e v e r y u se fu l if som ebody w ould ta k e th e t im e and tro u b le to do a b ig s e r ie s of t e s t s and to p ro d u ce so m e r e l ia b le q u an tita tiv e ev idence r e g a rd in g gas evolu tion , p r e s s u r e r i s e , e t c . , so a s to r e a s s u r e th e r e a c to r o p e ra to rs .

M. DOUÏS: It s e e m s f ro m w hat you say th a t, in p r in c ip le , a s a gene r a l ru le , th e f ig u re of 5 a tm i s th e lim itin g p r e s s u r e fo r y o u r i r ra d ia t io n s . How w as th is f ig u re a r r iv e d at?


C. TAYLOR: I t is an a r b i t r a r y f ig u re . It i s a f ig u re a s su m e d to bere a s o n a b le . I have b een q u es tio n in g it r e c e n tly b e c a u se I w as in te re s te d in i r r a d ia t in g xenon a t m uch h ig h e r p r e s s u r e s fo r p ro d u c tio n of io d in e-1 2 5 . I w anted to go up to 100 a tm in a s te e l p r e s s u r e v e s s e l and, as I have a lre ad y m en tio n ed , in th e c o u r s e of m y in q u ir ie s I found to m y s u r p r i s e th a t so m e body w a s i r r a d ia t in g a t 50 a tm in a q u a r tz am p o u le —th o u g h a d m itte d ly i t w as a v e ry s m a ll q u a r tz am p o u le and of c o u r s e i t i s m uch e a s ie r to r e ta in a h ig h e r p r e s s u r e in a v e s s e l of v e ry s m a ll d ia m e te r .

In m an y r e a c to r s , of c o u rs e , peo p le ru n e n g in e e rin g lo o p s w ith v e ry h igh p r e s s u r e s indeed in th e p ip ing , but th is s e e m s to m e to be s im p le r than i r ra d ia t in g se a le d c y lin d e rs . One fe e ls th a t a se a le d cy lin d e r is m o re lia b le to fa i l th an a p r e s s u r e p ipe , w hich e n te r s and le a v e s th e r e a c to r and h as a ll th e co n n ectio n s o u ts id e it.

W. BO C K-W ER TH M A N N : I shou ld l ik e to com e b a c k o n ce m o r e toth e u n u su a l so d iu m co n ten t of y o u r a lu m in iu m . Did you r e f e r y o u r sod ium m e a s u re m e n ts to sod ium s ta n d a rd s w hich had been ir ra d ia te d w ith and w ith o u t c a d m iu m s h ie ld in g ? If n o t, you w ou ld g e t a w ro n g v a lu e b e c a u s e th e c a d m iu m s h ie ld in g t a k e s off th e r e s o n a n c e c a p tu r e .

C. TAYLOR: No. It w ill ta k e th e re s o n a n c e n e u tro n s and w ill a lsota k e aw ay th e th e rm a l n eu tro n s; su re ly it w ill c o n s id e rab ly red u c e th e a c tiv ity p ro d u ced in sodium by th e (n, 7 ) rea c tio n ?

W. BO C K-W ERTHM ANN: No. If you r e f e r to s ta n d a rd s w hich a r en o t sh ie ld e d w ith cadm ium , th en you r e f e r to s ta n d a rd s w hich have two a c t i v itie s : one p ro d u ced by th e rm a l n eu tro n s , the o th e r p roduced by e p ith e rm a l n e u tro n s in th e m id d le e n e rg y re g io n , so th a t you h av e no p ro p o r tio n a li ty . T h is cou ld r e s u l t in w ro n g v a lu e s fo r th e so d iu m co n ten t.

C. TAYLOR: Y es, I se e . It is p o ss ib le . We w ere only doing a roughch eck , and I h av e n o t got any p r o p e r r e s u l t s . A ll I am conv inced of i s th a t we a r e g e ttin g m o re N a ?4 p ro d u ced by th is th e rm a l-n e u tro n ac tiv a tio n th an I expected .

P . A EBERSO LD : W ith r e g a r d to th is p o in t, I m y s e lf c o n s id e r i t tob e d e s i r a b le to u s e 96% m a g n e s iu m a lu m in iu m a llo y fo r h ig h -f lu x r e a c to r i r r a d ia t io n s .

C. T A Y LO R : B u t I th in k y o u w ill g e t so m e N a 24 f ro m th a t a ls o ?P . C. A E B E R S O L D : Y e s , b u t m u c h l e s s .C. TAYLOR: So th e m a in advan tage i s th a t you do no t g e t any of th e

a lu m in iu m a c tiv ity — o r v e ry l i t t le of it?P . C. AEBERSOLD: Y es.

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ НА РЕАКТОРЕ ВВР-М

И.А. КОНДУРОВ и Д.А. ЯЩИН ФИЗИКО-ТЕХНИЧЕСКИЙ ИНСТИТУТ им". А.ф. ИОФФЕ АН. СССР

СССР


PRODUCTION OF SHORT-LIVED ISOTOPES IN THE VVR-M REACTOR. T he paper discusses the production o f short-lived isotopes in the W R -M reactor, from the loading of the sam ple for irrad ia tion to its ex trac tion from the ho t cham bers.

The m echanism developed a t the P hysico-T echnical Institu te for handling the containers with the irradiated samples can be used in a ll existing and projected reactors with eccentric upper shielding covers. The irradiated samples are extracted with the a id of an unloading box designed and constructed to suit conditions in the W R -M reactor.

A long with the standard method of producing radioisotopes, various experim ental facilities for carrying out research on short-lived isotopes are described. In particu lar, a description is given of special equipm ent for research on F20 (T i = 10.7 s) and Mn56 (T ^ = 2 .5 h) and of apparatus for studying radioactive isotopes with a h a lf- l ife of 0. 01 s or less; other procedures em ployed in the horizon ta l and v e rtica l channels of die W R -M reactor for studying short-lived isotopes are a b o described.

PRODUCTION DE RADIOISOTOPES DE COURTE PERIODE' DANS LE REACTEUR VVR-M. Les auteurs exam inent le système de fabrication de radioisotopes de courte période dans le réacteur W R -M , depuis l'in tro duction de l'échantillon aux fins d 'irradiation jusqu'à sa sortie des chambres chaudes.

Le mécanism e mis au point à l'Institu t physico-technique pour la m anutention des récipients contenant les échantillons à irradier peut être appliqué à tous les réacteurs en fonctionnement ou en projet qui comportent des couvercles excentriques dans la partie supérieure de l 'éc ra n de protection. L 'ex traction des échantillons irradiés se fa it à l 'a id e d 'une bofte de déchargem ent spéc ia lem en t conçue pour le réacteu r VVR-M.

Outre la m éthode standard de production des radioisotopes, les auteurs exam inen t certains dispositifs expérim entaux perm ettan t d 'e ffec tuer des recherches physiques sur les radioisotopes de courte période. Ils décrivent notam m ent un dispositif spécial pour l 'é tu d e de 20F (T j = 10, 7 s) e t « М п ( Т | = 2 ,5 h) e t des appareils destinés à l 'é tu d e de radioisotopes dont la période est ég a le ou inférieure à 0 ,01 s. Ils exposent en outre certa ines autres m éthodes em ployées pour l 'é tu d e des isotopes de courte période dans les canaux horizontaux e t verticaux du réacteur VVR-M.

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ НА РЕАКТОРЕ ВВР-М. Рассматривается схема получения короткоживущих радиоизотопов на реакторе ВВР-М от загрузки образца на облучение до выдачи его из горячих камер.

Разработанный в Ф1И механизм для перегрузки контейнеров с облучаемыми образцами может быть применен на всех действующих и проектируемых реакторах с эксцентричными верхними защитными крышками. Выгрузка облученных образцов производится через разгрузочный бокс, спроектированный и изготовленный с учетом условий работы реактора ВВР-М.

Кроме стандартной схемы производства радиоизотопов, рассматривается некоторое экспериментальные устройства для проведения Физических исследований с короткохивущими изотопами. В частности, приводится описание специальной аппаратуры для исследования F2°(T¿ - 10,7сек.), Mn56(T¿ « 2 ,5 часа), установки для изучения радиоактивных изотопов с периодами полураспада ь 0,01 сек и других методик, применяемых на горизонтальных и вертикальных каналах реактора ВВР-М для изучения короткоживущих изотопов.

PRODUCCIÓN DE RADIOISÓTOPOS DE PERIODO CORTO EN EL REACTOR W R -M . Los autores examinan e l esquema de producción de radioisótopos de período corto en e l reactor W R -M , desde la introducción de las muestras para su irradiación hasta su extracción de las cámaras de elevada actividad.

83

84 И.А. КОНДУРОВ и Д. А . ЯШИН

El m ecanism o ideado en e l Instituto de Física técn ica para la carga y descarga de los recip ientes que contienen las muestras puede utilizarse en todos los reactores provistos en su parte superior de tapas de blindaje excéntricas. La muestras irradiadas se extraen m ediante una caja de descarga, proyectada y construida para e l reactor W R -M .

Además del método corriente de producción de radioisótopos, se exam inan algunas instalaciones experim entales para efectuar investigaciones físicas con isótopos de período corto. En p articu lar, se describen los aparatos especiales para efectuar investigaciones con » F (T^ = I 0 ,7 s ) , 56 Mn (T i = 2 , 5 h ) , la instalación para estudiar los isótopos radiactivos de período > 0,01 st y otros métodos utilizados en los canales horizontales y verticales del reactor W R -M para trabajar con isótopos de período corto.

ВВЕДЕНИЕ

Короткоживущие изотопы являются менее исследованной областью по сравнению с изотопами, периоды полураспада которых от нескольких часов и больше. Это объясняется тем, что исследования короткоживущих изотопов требуют выполнения двух условий: наличия высоких потоков тепловых нейтронов и создания устройств для быстрой транспортировки изотопа из места облучения к измерительной аппаратуре .

При проектировании реактора ВВР-М задача исследований на нем короткоживущих изотопов являлась частью программы научных исследований. Основные усилия были направлены на создание такой активной зоны, которая позволила бы получить ряд каналов с высоким потоком тепловых нейтронов.

В результате в вертикальных каналах реактора приготовление короткоживущих изотопов может проводиться в потоках до 3"1014 н/см2 -сек. Система транспортировки облученного изотопа из вертикальных каналов потребителю позволяет производить в этих каналах изотопы с периодами полураспада более 10 мин. Для исследований изотопов с меньшими периодами полураспада (до сотых долей секунды) в Физико-Техническом институте АН СССР изготовлены экспериментальные устройства, работающие на горизонтальных каналах реактора. Эти установки позволяют быстро транспортировать облученный изотоп из места облучения к измерительной аппаратуре. В зависимости от характера экспериментальной установки получение короткоживущих изотопов в горизонтальных каналах проводится в потоках тепловых нейтронов от 10s до 9*10г3 н/см2>сек.

ИСПОЛЬЗОВАНИЕ ВЕРТИКАЛЬНЫХ КАНАЛОВ РЕАКТОРА

Произвадство изотопов на реакторе ВВР-М ведется в экспериментальных каналах, расположенных как непосредственно в активной зоне, так и в бериллиевом отражателе (рис.1). В активной зоне реактора имеется водная полость с экспериментальным каналом. При загрузке активной зоны водная полость может быть создана в различных местах, поэтому на рисунке она не показана .

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ 85

П лан эк с п е р и м ен т а л ь н ы х к а н а л о в р е а к т о р а :1 - к ан а л ы те п л о в о й ко л о н н ы ; 2 - к а н а л д л я защ итной п р о б к и , ф 6 8 ;3 - кан ал ы п е р е д а ч и о б р а зц о в в г о р я ч и е л а б о р а т о р и и ; 4 - - к а н а лд ^ я защ и тной п р о б к и , Ф 6 0 ; 5 - кан ал ы д л я защ итны х п р о б о к , Ф 4 0 ;6 - к ан ал ы п ер в о й груп пы д л я п о л у ч е н и ея и з о т о п о в ; 7 - э к с п е р и м ен тальн ы й к а н а л , 0 6 2 ; 8 - эк с п ер и м ен таль н ы й к а н а л , 0 1 0 0 ;9 - к а н а л д л я защ итной п р о б к и , Ф 4 0 ; 10 - эк сп е р и м ен тал ь н ы е каналыФ 4 0 , три к а н а л а ; 11 - к а н а л д л я защ итной п р о б к и , Ф 4 0 ; 12 -каналыв т о р о й трупы д л я п о лу ч ен и я и з о т о п о в , четы р е к а н а л а ; 13 - кан алы д л я защ итны х п р о б о к , Ф 4 0 , три к а н а л а .

Поток тепловых нейтронов в канале водной полости составляет 3 " 1 0 1 4 н /с м 2 - с е к .*

Для производства изотопов в бериллиевом отражателе расположены 10 экспериментальных каналов. Потоки тепловых ней -

* Все потоки тепловых нейтронов приводятся для номинальной мощности реактора 10 Мвт.

86 И.А. КОНДУРОВ и Д .А . ЯШИН

тронов в каналах бериллиевого отражателя лежат в пределах от 6-1013 н/см2-сек до 1,4-1014 н/см2-сек. Для удобства обслуживания большинство экспериментальных каналов сухие. Каналы закрываются сверху защитными пробками для снижения фона под защитными крышками при работе реактора.

По данным опытов, проведенных на критическом стенде ВВР-М, одной из важных особенностей каналов в бериллиевом отражателе является то, что помещение в них образцов с большим сечением захвата тепловых нейтронов не сказывается заметно на реактивность реактора. Так, помещение кадмиевого цилиндра диаметром 110 мм, высотой 600 мм при толщине стенки 1 мм привело к изменение реактивности всего лишь на 0,2%. Это говорит о том, что для проведения работ по облучению материалов в экспериментальных каналах реактора не требуется большого запаса реактивности.

Цикл облучения образца в каналах реактора и его дальнейшей транспортировки потребителю представлен на рис.2. Загрузка контейнеров с образцами в экспериментальные каналы (1) реактора и разгрузка после облучения в горячие камеры производится загрузочным устройством, которое установлено на верхней малой защитной крышке (2) реактора. Малая крышка расположена эксцентрично относительно большой крышки (3), поэтому при их вращении имеется возможность обслуживания загрузочным устройством всех экспериментальных каналов.

Для загрузки контейнера в экспериментальный канал проходное отверстие в малой защитной крышке совмещается с нужным каналом. Через загрузочное устройство контейнер помещается в канал предварительной загрузки (4), расположенный в малой защитной крышке. Дальнейшая перегрузка в экспериментальный канал производится с помощью электромагнитного захвата (5), подвешенного на гибком кабеле, и поворотного барабана (6) загрузочного устройства. Перемещение электромагнитного захвата осуществляется с помощью лебедки. На время загрузки контейнера в экспериментальный канал защитная пробка из этого канала помещается в загрузочное устройство.

После окончания экспозиции облученный контейнер с помощью лебедки опускается через канал транспортировки (7) и наклонный канал (8) в горячую камеру № 1. Здесь контейнер вскрывается либо манипулятором (9), либо винтовертом (10), либо разрезается на станке (11). Использованные контейнеры помещаются в хранили- лище (12) и после достаточной выдержки отправляются в могильник. Облученный изотоп перекладывается в чистый алюминиевый пенал и на транспортной тележке (13) отправляется в горячую камеру Н§ 4, Отсюда он подается в разгрузочный бокс, где помещается в транспортный контейнер (14). Транспортный контейнер заранее устанавливается на откатную платформу и подкатывается в рабочее положение. После открытия защитного шибера (16) пенал с облученным изотопом на тележке (17) вдвигается в разгрузочный бокс. Операции по перегрузке изотопа в транспортный контейнер производятся манипулятором (18) .


иииии—— Н ш | Н¡Й Р5̂ ï * ^и ^ т . j - J и м у л Я к Я

В .... }ЩВ9 .. • JfljBЩ: ' м Ш Ш

■ь. wf'щШг'-® т | ■ ЩЯШ

:

Р и о .2

С хем а п р и г о т о в л е н и я и з о т о п о в в в е р т и к а л ь н ы х к а н а л а х р е а к т о р а и и х в ы д а ч и :1 - э к с п е р и м е н т а л ь н ы е к а н а л ы ;2 - м а л а я за щ и т н а я кры ш ка;3 - б о л ьш ая за щ и т н а я кры ш ка;4 - к а н а л п р е д в а р и т е л ь н о й з а г р у з к и ;5 - э л е к т р о м а г н и т н ы й з а х в а т ;6 - п о в о р о тн ы й б а р а б а н ;7 - к а н а л т р а н с п о р т и р о в к и ;8 - н аклон н ы й к а н а л ;

м а н и п у л я т о р ;9101 11213

в и н т о в е р т ; с т а н о к ; хран и л и щ е ;т р а н с п о р т н а я т е л е х к а ;

14 - т р а н с п о р т н ы й к о н т е й н е р ;15 - о т к а т н а я п л а т ф о р м а ;16 - защ итны й п ш бер ;17 - т е л е ж к а ;18 - м а н и п у л я т о р .

В том случае, если период полураспада облучаемого изотопа составляет несколько минут, рассмотренная схема транспортировки потребителю неприемлема, так как полное время от выгрузки облученного изотопа из канала реактора до перегрузки его в транспортный контейнер составляет 15-Ü0 мин. Эти изотопы могут выдаваться потребителю через верхние крышки реактора. В этом случае облученный образец извлекается из. канала реактора электромагнитным захатом загрузочного устройства и помещается в канал предварительной загрузки. Дальнейшая перегрузка в транспортный контейнер производится удлиненными захватами. Полное время перегрузки изотопа в транспортный контейнер при этом составляет 3-5 мин.

88 И.А. КОНДУРОВ и Д.А. ЯШИН

Несложное приспособление, изображенное на рис.З, позволяет в некоторых случаях работать с короткоживущими изотопами большой

Р и с .З

С хем а п р и сп о с о б л е н и я д л я б ы стр о го перем ещ ения о б р а зц а и з а к т и в н о й зоны в тепловую н о ло н н у :

1 - о б р а з е ц ; 2 - ж е л о б ; 3 - в о р о н к а ; 4 - т е п л о в а я к о л о н н а ; 5 - изм е р и те л ь н о е у с т р о й с т в о .

активности - свыше 1000 кюри. На рисунке приведена схема опыта, в котором требовалось образец, облученный в водной полости активной зоны реактора, перенести к измерительному устройству.Зз::ду большой активности образца, измерения проводились в тепловой колонне, которая использовалась как защита. Работа проводилась следующим образом. Образец в контейнере из чистого алюминия опускался в водную полость на капроновой нити толщиной 0,8-1,0мм. Свободный конец нити продевался сквозь кольцо под воронкой (3) и протягивался на расстояние 10 м в помещение, имеющее хорошую защиту от излучения и толстое смотровое стекло. После окончания облучения контейнер с помощью нити вытягивался из активной зоны по желобу (‘¿), скользил к воронке (3) и через нее опускался к измерительному устройству (bj. Вся операция занимала не более 3-4 мин.


ИСПОЛЬЗОВАНИЕ ГОРИЗОНТАЛЬНЫХ КАНАЛОВ РЕАКТОРА

Ряд горизонтальных каналов реактора ФТИ оборудован установками, позволяющими получать и исследовать короткоживущие радиоактивные изотопы. Эти устройства обеспечивают облучение образцов в нейтронном потоке и быструю доставку их к измерительной аппаратуре.

Маятниковая почта,разработанная В.В. Даниловым, И.А. Конду- ровым и Р.Д. Шахетом, схематически изображена на рис.4. Она предназначена для работы с наиболее короткоживущими изотопами - с

Р и о .4

М аятн и ков ая п о ч т а :1 - о б р а з е ц ; 2 и 3 ■ э л е к тр о м а г н и т ы ; 4 - ФУУ; D - с в и н е ц ; tí - т р а - фин с б о р о м .

временами жизни до сотых долей секунды. Исследуемый образец (1) в виде фольги или спрессованного порошка в плексигласовой коробке укрепляется на конце пружинного маятника. Когда маятник находится в правом (на рисунке] положении, образец облучается в нейтронном потоке 109 н/см2»сек из горизонтального канала реактора. При переходе маятника в другое крайнее положение образец перемещается в защиту и располагается перед кристаллами сцинтилляцион- ного спектрометра.Маятник удерживается в крайних положениях с помощью электромагнитов (2) и (3). Если маятник находится в левом положении, то для перевода его в правое достаточно изменить направление тока в обмотке электромагнита(3).Ток другого электромагнита остается при этом неизменным. Освободившийся маятник

90 И.А. КОНДУРОВ и Д. А . ЯШИН

движется вправо. Инерции маятника достаточно для того, чтобы подойти к электромагниту (2) на расстояние порядка 5 мм, где ухе начинает сказываться сила притяжения электромагнита. Ввиду того, что маятник подходит к магниту с нулевой скоростью и притягивается с малого расстояния, сила удара при остановке оказывается очень незначительной.

Весь процесс перемещения образца на расстояние 40 см занимает 0,04 сек. Время пребывания образца под облучением и на измерении зависит от времени жизни исследуемого изотопа: облучение длится около двух, а измерение - около четырех периодов полураспада. Программа работы маятниковой почты задается шаговым искателем, который управляет переключающими реле и запускает электронную аппаратуру для регистрации излучений. На описанной установке исследовалось \_излУчение короткоживущих изотопов:

Hfi7em (19 сек), w x83m (5 í5 сек), Inll4m (2,5 сек),

Yb177m (6 сек), Yb17Sm (0,06 сек) и др.

На рис.5 приведена схема установки, на которой В.М. Лобашо- вым и В.А. Назаренко было проведено исследование поляризационной корреляции при Р-распаде FatJ L1J * Радиоактивный F2U с периодом полураспада 10,7 сек. получался в горизонтальном канале реактора вблизи бериллиевого отражателя ('поток нейтронов ~ 3 ‘1013) и передавался по полиэтиленовой трубке в измерительную установку. Принцип работы всей системы состоит в следующем. Газообразный водород из боллона (1) через вентиль (2) после предварительной очистки в холодильнике (3) поступал по трубке в полиэтиленовый сосуд (5) с пористой перегородкой. В сосуде был налит жидкий фторзамещенный углеводород, содержащий (CnF 2n)• При прохождении через жидкость водород захватывал "горячие" атомы фтора, возникающие в момент (n,Y) реакции, и уносил их по выходной трубке в полиэтиленовую коробочку (6J, где находилась охлаждаемая сухим льдом медная фольга толщиной около 10 мк. Молекулы HF оседали на меди, образуя тем самым источник радиоактивного F20. Водород же после очистки в холодильнике (7) и в стакане с водой (8) выходил в атмосферу. Стальная пробка (4) длиной 1,2 м с изогнутой щелью служила для защиты от быстрых нейтронов из горизонтального канала.Эта же пробка с двумя полиэтиленовыми трубками была использована для получения радиоактивного Мпьа (Т^ = 2,6 час). В этом случае образец MnS5, помещенный в полиэтиленовую капсулу, перемещался вдоль трубки с помощью стального тросика. Время перемещения образца 10-20 сек.

"Почта", изображенная на рис.6, является частью кристалл- диффракционного гамма-спектрометра, описанного О.И. Сумбаевым иА.И. Смирновым [2]. Спектрометр предназначен для исследования Y-лучей, возникающих в момент (п,\) реакции. При этом исследуемый образец находится в горизонтальном канале непосредственно около активной зоны. Условия фокусировки прибора позволяют перемещать

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ

Р и с .5

С хем а у с т а н о в к и д л я р аб оты с короткож ивущ им F * 0 :1 - б ал л о н с в о д о р о д о м ; И - в е н т и л ь ; 3 - х о л о д и л ь н и к ; 4 - с т а л ь н а я п р о б н а ; 5 - с о с у д с п о р и сто й п е р е г о р о д к о й ; 6 - 'и с т о ч н и к F2U;7 - х о л о д и л ь н и к ; 8 с т а к а н о в о д о й .

Р и с . 6

"П о ч та" кр и ста л л -д и ф ф р аж ц и о н н о го г а м м а -с п е к т р о м е т р а :1 - о б р а з е ц ; 2 - ц и л и н д р ; 3 - ш то к ; 4 - борный ф и л ь т р ; 5 -к о л л и м а т о р .

92 И. А. КОНДУРОВ и Д. А. ЯШИН

источник гамма-лучей вдоль канала на значительные расстояния. Эта особенность прибора позволяет исследовать гамма-излучение короткоживущих изотопов без выключенния реактора путем попеременного помещения образца то в зону с большим нейтронным потоком (~10i3 н/сма сек), то к коллиматору, где нейтронный поток падает более, чем в 1000 раз и все гамма-излучение определяется только наведенной радиоактивностью образца.

Устройство почты ясно из рис.6. Образец (1), находящийся в цилиндре (2), может перемещаться по трубе с помощью штока (3). Движение штоку передается стальным тросиком. Тросик намотан на барабан и может перемещать образец на расстояние 0,6 м. Барабан приводится во вращение реверсивным двигателем с дистанционным управлением (6). Время полного перемещения образца около 10 сек.

Два горизонтальных канала реактора предназначены для исследования короткоживущих изотопов с помощью пневмопочт. Одна из пневмопочт за время порядка 0,5 сек доставляет образец из начала горизонтального канала (поток 6-1013 н/см2 сек) внутрь тороидального Э-опектрометра. Эта установка позволяет исследовать S-спектры и спектры конверсионных электронов короткоживущих изотопов.

Вторая пневмопочта, предначенная для работы с магнитным гамма-спектрометром по электронам отдачи, обеспечивает облучение одного образца и одновременное измерение другого. По прошествии времени порядка периода полураспада образцы меняются местами. Полное время транспортировки около 10 сек.

Авторы благодарны Д.М. Каминкеру и К.А. Коноплеву за помощь в составлении доклада и Ю.Г. Косьянковскому за оформление иллюстраций .

ЛИТЕРАТУРА

[1] ЛОБАШОВ В.М., НАЗАРЕНКО В.А., ЖЭТФ, 42, 2 (1962) 370.[2] СУМБАЕВ О.И., СМИРНОВ А.И., Nucl. Instr.'and Method ( в печати).

HANDLING AND SEPARATION OF SHORT-LIVEDRADIOISOTOPES FROM RESEARCH REACTORS

W. W. MEINKE UNIVERSITY OF MICHIGAN, ANN ARBOR, M IC H .,



HANDLING AND SEPARATION OF SHORT-LIVED RADIOISOTOPES FROM RESEARCH REACTORS. The use of radioisotopes has often been lim ited to those with half-lives greater than a day because of the remoteness of the supplying reactor. This encouraged a leisurely approach to processing and utilization, and in turn fostered a reluctance on the part of the user to even consider the potentialities of many shorter-lived isotopes.

With the availab ility of research reactors throughout the world this re liance on distant isotope producers can be served, and a t the sam e tim e m any new fields of experim entation with short-lived isotopes can be exp lo ited . To accom plish this, how ever, requires a new approach to tracer production.

For alm ost five years the programm e with the University of Michigan research reactor has involved die handling, processing, and m easuring of short-lived isotopes. Routine work is done with isotopes with h a lf- lives not only of hours, but even of minutes. While much effort has been d irected towards the field of a c t ivation analysis, the equ ipm en t, techniques and procedures used a re ap p lic ab le to m any o ther areas.

To exploit short-lived isotopes i t is not essential to have large stocks of isotopes, nor three-shift reactor operation, nor elaborate processing facilities. Indeed, simple positive-action tongs and straight-forward procedures usually prove more satisfactory than elaborate rem ote manipulations.

The heart of the system is the reacto r pneum atic-tube fa c ility which delivers sam ples to a hood in a laboratory adjoining the reactor w ithin three seconds after irradiation . Dissolution and rapid rad iochem ical separations can then be perform ed d irec tly on the sam ple w ithout further transfer.

Separation procedures adaptable to this short-tim e scale (few minutes) include not only solvent extraction, anion exchange and p rec ip ita tio n , bu t also new types, such as iso topic exchange and a m alg am exchange. Many new techniques, such as extensions of e lectrom igration and paper chromatography, thin layer chrom atography, gas chromatography, selective d istillation, selective reduction, e t c . , also add to the variety of separation possibilities to be explored.

The local research reactor, whether i t is in a university in the United States, or in a developing country, thus opens a whole new era of tracer possibilities.

MANIPULATION ET SEPARATION DES RADIOISOTOPES A COURTE PERIODE PRODUITS DANS DES REACTEURS DE RECHERCHE. L'emploi des radioisotopes a souvent été lim ité aux radioisotopes dont la période est supérieure à un jour, é tan t donné l'é lo ig n em e n t du réacteu r qui les produit. C ec i explique un certa in m anque d 'in té rê t à l’égard du tra item en t e t de l'u tilisa tio n de ces radioisotopes, e t par suite une certa ine ré ticence de la part du consomm ateur à envisager m êm e les possibilités d 'em ploi de nombreux radioisotopes à courte période.

Com m e i l existe m ain tenan t de nombreux réacteurs de recherche dans le monde, les laboratoires ne dépendent plus de producteurs de radioisotopes éloignés; en outre, les radioisotopes à courte période couvrent de nombreux champs d 'expérim entation nouveaux. Il im porte, cependant, à cette fin de considérer la production des radioindicateurs sous un angle nouveau.

Depuis près de cinq années, le programm e exécuté au m oyen du réacteur de recherche de l'Université du M ichigan com porte la m anipulation , le tra item en t e t la m esure de radioisotopes à courte période. Les chercheurs de l'U niversité em ploient couram m ent des radioisotopes dont les périodes ne dépassent pas plusieurs heures, voire quelques minutes. Les traveaux entrepris jusqu'à présent avaient tra it principalem ent à l'analyse par activation , mais le m a té ria l, les méthodes e t les techniques utilisés.peuvent s’appliquer à de nombreux autres domaines.

Pour u tiliser les radioisotopes à courte période, il n 'e s t pas nécessaire de prévoir un roulem ent de trois équipes pour le réacteur; il n 'e s t pas lion plus indispensable de disposer de stocks importants de radioisotopes, ni d ’installations de tra item en t perfectionnées.En fa it, de simples pinces, utilisées de la m anière courante, donnent généralem ent de m eilleurs résultats que de com plexes m anipulations télécom m andées.

93

94 W.W. MEINKE

L'essentiel du système utilisé est l’installation à tubes pneumatiques du réacteur qui am ène les échantillons dans la h o tte d’un laborato ire proche du réacteur dans les trois secondes qui suivent l 'irrad ia tio n . La dissolution e t les séparations radiochimiques rapides peuvent alors être effectuées d irectem ent sur l'échantillon sans q u 'il soit nécessaire de le transporter â nouveau.

Pendant la courte période dont on dispose (quelques m inutes), la séparation peut se faire non seulement par ex traction par solvant, par échange d*anions e t par préc ip ita tion , mais aussi par de nouvelles méthodes telles que l’échange isotopique e t 1*échange par am algam e. De nombreuses techniques nouvelles employées dans divers domaines — électrom igration e t chrom atographie sur papier, chrom atographie en couche m ince, chromatographie en phase gazeuse, distillation sélective, réduction sélective, etc. — viennent encore ajouter à la variété des possibilités de séparation qui n’ont pas encore été explorées.

La présence d’un réacteur de recherche sur p lac e , que ce soit dans une université des Etats-Unis ou dans un pays en voie de développement, ouvre donc une ère entièrem ent nouvelle aux possibilités d’applications des radioindicateurs.

ПОЛУЧЕНИЕ И ОТДЕЛЕНИЕ КОРОТКОЖИВУЩИХ ИЗОТОПОВ В ИССЛЕДОВАТЕЛЬСКИХ РЕАКТОРАХ* Применение изотопов иэ-эа удаленности от снабжавшего реактора часто ограничивалось теми, которые имеет период полураспада больше одного дня. Это тормозило исследования в области производства и применения радиоизотопов вообще и в то же время мешало потребителе точно оценить возможности многих короткоживущих изотопов.

В связи с наличием во всем мире исследовательских реакторов эта зависимость от места производства изотопов может представлять собой известную трудность, но в то же время она дает возможность проводить ряд новых экспериментов с короткоживущими изотопами. Для этого требуется вплотную подойти к вопросам производства меченых атомов.

Почти в течение пяти лет программа работы ка исследовательском реакторе Мичиганского университета включала обработку, переработку и измерение короткоживущих изотопов. Обычно пользовались изотопами, продолжительность полураспада которых равнялась часам и даже минутам. Хотя в данном случае главные усилия были направлены на исследования в области активационного анализа, использовавшееся оборудование и методика могут быть применены и для других исследований.

Для получения короткоживущих изотопов не обязательно иметь совершенное оборудование, большие запасы изотопов или поддерживать трехсменную работу реактора. При уверенном обращении с простыми манипуляторами можно получить лучшие результаты, чем дистанционным управлением.

Основой системы, описываемой в докладе, является приспособление в виде пневматической трубы, которая доставляет образцы в вытяжной колпак лаборатории, примыкающей к реактору, в течение трех секунд после облучения. Растворение и быстрое отделение радиохимическим способом может производиться без дальнейшего перемещения образца.

Методы отделения, легко приспосабливаемые для кратковременной шкалы (несколько минут), включают не только селективную экстракцию, анионный обмен и осаждение, но и такие новые методики, как изотопный обмен и амальгамный обмен. Появление таких методик, как электромиграция и хроматография на бумаге, тонкослойная хроматография, газовая хроматография, селективная дестилляция, селективное восстановление и т.д. также расширяет возможности способа отделения, которые должны быть изучены.

Местный исследовательский реактор, будь то в университете в Соединенных Штатах иди в какой- либо развивающейся стране мира, открывает, таким образом, новую эру в использовании возможностей меченных атомов.

MANIPULACION Y SEPARACION DE RADIOISOTOPOS DE PERIODO CORTO OBTENIDOS EN REACTORES DE INVESTIGACIÓN. Hasta hace algunos aflos, los radioisótopos de período in terior no se em pleaban con m ucha frecuencia porque los reactores destinados a produciros solían encontrarse a gran distancia del lugar de su u tilizac ión . Debido a este hecho , no se dedicaron mayores esfuerzos a l estudio de su obtención y sus posibles em pleos, lo que, a su vez, hizo que los usuarios no pensaran siquiera en las posibilidades que algunos de ellos ofrecen.

Como hoy se dispone en casi todo e l mundo de reactores de investigación, no se depende ya de productores situados a gran distancia y, así, se abren muchos campos nuevos de experim entación con isótopos de período corto. No obstante, para conseguirlo es preciso enfocar de modo distinto la producción de indicadores.

Durante casi cinco años, e l program m a del reactor de investigación de la Universidad de M ichigan ha incluido la manipulación, purificación y medición de isótopos de período corto. Hoy se trabaja corrientemente en aquel laboratorio con isótopos cuyos períodos no son sólo de horas, sino incluso de m inutos. Muchos de

HANDLING AND SEPARATION OF SHORT-LIVED RADIOISOTOPES 95

los trabajos guardan re lac ión con e l análisis por activ ac ió n , pero e l equipo, las técn icas y procedim ientos em pleados son tam bién ap licab les en muchos otros cam pos.

Para provechar los isótopos de período corto, no es esencial disponer de grandes reservas de radioelementos ni trabajar en tres turnos en e l reactor, así como tampoco son necesarias instalaciones complicades. En general, es más satisfactorio u tilizar dispositivos sencillos, como pinzas de acción directa , en vez de em plear com plicados mecanismos de m anipulación a distancia.

El dispositivo c lave del sistem a es la instalación de transporte neum ático del reac to r, que en e l plazo de 3 s lleva las muestras a la vitrina de un laboratorio contiguo a l reactor. Esto perm ite disolver directam ente la muestra y proceder rápidam ente a las separaciones radioquím icas, sin necesidad de transportarla a otro sitio.

Los procedim ientos de separación u tilizab les en períodos de tiem po tan cortos (algunos minutos) son no solam ente la extracción con disolventes, e l intercam bio iónico y la p recip itación , sino tam bién métodos nuevos como el intercam bio isotópico y e l intercam bio entre am algam as. Muchas otras técnicas nuevas como la e lectrom igración y la crom atografía sobre papel, la crom atografía en capas delgadas o en fase gaseosa, la destilación y la reducción selectivas, e t c . , ofrecen toda una serie de posibilidades de separación que m erecen ser exploradas.

Así, e l reactor de investigación , tan to si está situado en una Universidad estadounidense com o en e l país más le jano en vías de desarro llo , abre un vasto cam po de ap licaciones a los indicadores rad iactivos.

1. INTRODUCTION

W e h av e h e a rd th is m o rn in g abou t th e p ro d u c tio n of r a d io is o to p e s in som e of the la rg e r e a c to r c e n tre s . I would now like to m ention o u r experience w ith a u n iv e r s i ty r e s e a r c h r e a c to r s im i la r to th o s e a v a ila b le , o r so o n to be a v a ila b le in o v e r 50 lo c a tio n s th ro u g h o u t th e w o rld . O ur g ro u p h a s had m o re th a n fo u r y e a r s ’ e x p e r ie n c e w ith th is type of r e a c to r and m o s t of o u r w ork h as been w ith s h o r t h a lf- liv e d ra d io iso to p e s . A dm itted ly m uch of o u r w ork has been s lan ted to w ard s ac tiv a tio n an a ly s is but the p ra c tic a l experience we have gained and th e te ch n iq u e s we have developed a r e equa lly ap p licab le to rad io iso to p e p ro d u c tio n .

T ra d i t io n a l ly , s c ie n t i s t s h av e s e le c te d lo n g - liv e d r a d io is o to p e s fo r r a d ia t io n s o u r c e s and t r a c e r e x p e r im e n ts . In a few s p e c ia l c a s e s , su ch a s th e e a r ly w ork on 2 0 .4 -m in C 11 [1] , ingen ious te ch n iq u e s w ere d ev ised fo r th is s in g u la r t r a c e r of the im p o rta n t e lem en t ca rb o n . A lthough ex ce llen t w ork w as done w ith th is C11 t r a c e r , d is c o v e ry of th e lo n g -liv e d c a r b o n - 14 [2 ] h a s a lm o s t e lim in a te d the u se of th e s h o r te r - l iv e d iso to p e .

O ccasio n a lly n u c le a r p h y s ic is ts and c h e m is ts have b e s tir re d th e m se lv es w ith c e r ta in " s h o r t - c u t " te c h n iq u e s to o b ta in a sp e c if ic s h o r t- l iv e d r a d io iso to p e c le a n enough fo r n u c le a r c h a r a c te r iz a t io n . H ow ever, th e s e p r o c e d u re s a r e often only e ffec tiv e u n d e r c e r ta in id e a l cond itions when the ta rg e t (o r m a tr ix ) m a te r i a l can be c a re fu l ly s e le c te d , and a r e th u s no t a lw a y s g e n e ra lly ap p lica b le . (P ro c e d u re s of th is type have been co llec ted and c r o s s - r e f e r e n c e d in a r a d io c h e m ic a l te c h n iq u e s m o n o g ra p h by KUSAKA an d M EIN K E [3] . )

M uch of th e r a d io c h e m ic a l s e p a r a t io n in fo rm a tio n a v a ila b le in th e l i t e r a tu r e e m p h a s iz e s s e p a ra tio n s of lo n g -liv ed ra d io iso to p e s . T h is a p p e a rs to have b een a c a r r y - o v e r fro m th e e a r ly d ay s of W orld W ar II when r a d io c h e m ic a l p ro c e d u re s fo r f is s io n p ro d u c ts and o th e r ra d io iso to p e s had to be dev e lo p e d ra p id ly . P ro c e d u r e s w e re o ften on ly s lig h tly m o d ifie d v e r s io n s of leng thy c la s s ic a l a n a ly tic a l m e th o d s. S ince th e re w as no tim e to ev a lu a te each of s e v e ra l dozen s te p s in a sp e c if ic p ro c e d u re , if a given lengthy p ro c e d u re gave s a t is f a c to r y r e s u l t s , i ts u se w as continued in fu tu re s e p a ra tio n s .

96 W.W. MEINKE

S e p a ra tio n s in th e s e e a r l i e r d a y s of r a d io c h e m is tr y w e re lim ite d p r i m a r i ly to p re c ip ita tio n and c e r ta in c la s s ic a l a r e a s of d is t illa tio n and so lvent ex tra c tio n , which in g e n e ra l tended to be r a th e r lengthy.

T h e b e s t e x a m p le s a r e found in C O R Y E L L and SUGARM AN’s m o n u m e n ta l c o m p ila tio n [4] o f th e w a r - t im e r a d io c h e m ic a l s e p a r a t io n s p r o g ra m m e . M any new ra p id te c h n iq u e s and s p e c ia l r e a g e n ts have b ee n d e v e lo p ed in th e 1 1 y e a r s s in c e th is book a p p e a re d , a s can be s e e n by p e r u s a l of th e s e r i e s of m o n o g rap h s on th e " R a d io c h e m is try of th e E le m e n ts " [5] , y e t q u ite o ften s e p a ra t io n s a r e s t i l l m ade by th e old m e th o d s .

A t m any of th e l a r g e r a to m ic e n e rg y in s ta l la t io n s w h ere ro u tin e r a d io c h e m ic a l d e te r m in a t io n s a r e f re q u e n tly m a d e , te c h n ic ia n s w ith y e a r s of ex p e r ie n c e w ith old m ethods a re re lu c ta n t to t r y new tech n iq u es even though th ey a p p e a r to sav e tim e . T h is tendency in th e w e ll-e s ta b lish e d la b o ra to r ie s to e m p h a s iz e th e lo n g e r - l iv e d r a d io is o to p e s le a v e s a w id e -o p e n f ie ld fo r g roups w orking with r e s e a rc h r e a c to r s w hether they a re in new ly-estab lished national fa c ili t ie s o r in u n iv e rs i tie s .

2. D E F IN IT IO N O F SHORT H A L F -L IF E

W hen s c ie n t i s t s ta lk ab o u t u s in g s h o r t - l iv e d r a d io is o to p e s th e y a r e u s u a lly r e f e r r i n g to is o to p e s w ith h a l f - l iv e s o f a few h o u r s o r so . T he in fo rm a tio n s h e e t a t ta c h e d to th e a n n o u n c em en t of th is S e m in a r sh o w s f iv e is o to p e s h av in g h a l f - l iv e s g r e a te r th a n 1 d, fo u r is o to p e s w ith h a l f - l iv e s o f 8 - 24 h, fo u r is o to p e s b e tw e e n 1 - 8 h, and on ly one iso to p e ( C l 38 ) w ith a h a l f - l i f e o f l e s s th a n 1 h .

W hile ad m itte d ly th e r e a r e te c h n ic a l d if f ic u lt ie s in u s in g t r a c e r s w ith h a l f - l iv e s o f l e s s th a n 1 h, s i tu a tio n s o ften o c c u r in w hich h a l f - l iv e s of a few m in u te s ca n p ro v e to be a m a jo r a d v a n ta g e . I th e r e f o r e fe e l it to be e s s e n t i a l to b ro a d e n th e s p e c tru m of u s a b le h a l f - l iv e s in r a d io is o to p e s to in c lu d e th o s e of a few m in u te s .

O u r w o rk a t th e U n iv e r s i ty of M ich ig an h a s b ee n p r im a r i l y w ith h a lf - liv e s of th e o r d e r of m in u te s . T he 2 .3 -m in A gi°8 h a s th e s h o r te s t a c tiv ity th a t we have been ab le to s e p a ra te ra d io c h e m ic a lly , a lthough o u r a p p a ra tu s h a s b ee n u se d w ith o u t r a d io c h e m ic a l s e p a ra t io n to c h a r a c t e r i z e is o to p e s dow n to a 1 4 -s h a l f - l i f e [6 ] .

3. ADVANTAGES O F SHORT H A L F -L IF E

M uch of o u r e x p e r ie n c e a t th e U n iv e rs ity of M ich igan w ith s h o r t- l iv e d ra d io is o to p e s h a s b ee n in co n n ec tio n w ith a c tiv a tio n a n a ly s is , a lthough the f a c ili t ie s and tech n iq u es developed fo r th is p ro g ra m m e a re equally applicab le to o th e r rad io iso to p e u s e s .

O ur f i r s t w o rk w ith s h o r t- l iv e d ra d io iso to p e s and rap id ra d io c h e m ic a l s e p a ra tio n s w as a t B e rk e le y in con junction w ith a p ro g ra m m e of the c h a ra c te r i z a t io n of s e v e r a l new c o l la t e r a l s e r i e s of a lp h a -e m itt in g ra d io iso to p e c h a in s [7, 8 ] . A s m o re e n e rg y w as u til iz e d in th e c y c lo tro n b o m b ard m en t, s h o r t e r and s h o r t e r h a l f - l iv e d r a d io is o to p e s of a g iv e n e le m e n t, su c h a s


u ran iu m and p ro ta c tin iu m , w ere fo rm e d . T hus, w hile o u r w ork s ta r te d w ith1. 5 -d Pa229 j th e n ex t iso to p e c h a r a c te r iz e d w as 22 -h P a 228 , th en 3 8 -m in P a 22? , and la te r 1. 8 -m in P a 22̂ . At th a t tim e we found tha t, by using c e r ta in m a n ip u la to ry t r ic k s , th e s a m e type of so lv e n t e x t ra c tio n p ro c e d u re w hich gave c le a n s e p a ra tio n s fo r th e lo n g e r- l iv e d p ro ta c tin iu m iso to p e s could be a p p lie d in th e s e p a ra t io n o f th e 1. 8 - m in Pa226 . In r a p id p r o c e d u r e s th e i r r a d ia te d t a r g e t c r y s ta l s (d e liv e re d by a p n e u m a tic sy s te m ) cou ld be d i s so lved and e x tra c te d in a funnel lined w ith w et f i l te r p a p e r w hich would p a s s the aqueous la y e r but re ta in the o rg an ic one [9] .

W hen we beg an to d ev e lo p a p r o g ra m m e of a c tiv a tio n a n a ly s i s a t th e U n iv ers ity of M ichigan it th e re fo re seem ed n a tu ra l to t r y to exploit the sh o r tliv ed ra d io iso to p e s . It is t r u e th a t th e re a re c e r ta in ty p e s of t r a c e r e x p e r im e n ts w hich r e q u i r e m a n y hours- o r d a y s , and th u s c a ll f o r r a d io is o to p e s w ith long h a l f - l iv e s . B ut th e r e a r e a l a r g e n u m b e r of t r a c e r a p p l ic a tio n s in w hich th e h a l f - l if e of th e iso to p e is im m a te r ia l o r fo r w hich, a s in a c t i va tio n a n a ly s is , s h o r t- l iv e d iso to p e s can s h o r te n th e tim e of a n a ly s is co n s id e ra b ly .

T he s h o r t- l iv e d iso to p e i s ad v a n ta g eo u s in o th e r s i tu a tio n s a s i t soon d ecay s out, leav ing no re s id u a l ac tiv ity to con tam inate the en d -p ro d u c t. T h is is p a r t ic u la r ly im p o r ta n t in in d u s try w h ere th e e n d -p ro d u c t is d e s tin e d fo r u se by o r n e a r a c o n s u m e r .

To ex p lo it s h o r t- l iv e d iso to p e s it is on ly n e c e s s a r y to h av e a r e a c to r o r som e so u rc e of n u c le a r ac tiv a tio n in the n e a r v ic in ity . A num ber of y e a rs ago a s ta te m e n t th a t "the iso to p es would a ll be dead by the tim e they reached u s" would be a valid argum ent aga in st the use of sh o r t- liv e d iso to p es. Today, h o w ev er, an e q u a lly v a lid s u b s t i tu te fo r th is s ta te m e n t is th a t fo r th e i n s ta lla tio n with a r e s e a r c h r e a c to r , such a s we a r e d e sc rib in g in o u r S em in a r th is w eek, a w hole new sp e c tru m of r e s e a r c h p o te n tia l is a v a ila b le . To e x p lo it s h o r t- liv e d iso to p es it is not e s s e n tia l to have la rg e s to c k s of iso to p es, n o r t h r e e - s h i f t r e a c t o r o p e ra t io n , n o r e la b o r a te p r o c e s s in g f a c i l i t i e s .

4 . E Q U IP M E N T R E Q U IR ED

T he h e a r t of o u r s y s te m a t th e U n iv e rs i ty of M ich ig an i s th e r e a c to r - pn eu m atic tube fa c ility [1 0 ] , w hich d e l iv e rs sa m p le s to a hood in a la b o ra to ry ad jo in ing the r e a c to r w ithin th re e seconds a f te r ir ra d ia tio n . E x p erien ce a t B e rk e le y had show n th e im p o rta n c e of a pn eu m atic tube to b rin g sa m p le s f ro m th e s o u r c e of i r r a d ia t io n to th e r a d io c h e m ic a l s e p a r a t io n a r e a . In p la n n in g th e F o rd N u c le a r R e a c to r a t M ich igan , we th e r e f o r e in s i s te d on th e in s ta l la t io n of fo u r p n e u m a tic tu b e s a lo n g s id e th e c o r e . T h e s e tu b e s have b eco m e the "w ork h o r s e s " of the M ichigan R e a c to r . D uring fo u r y e a r s o f o p e ra tio n a t th e fu ll p o w er of 1 MW th e r e s e a r c h g ro u p a lone h a s m a d e m o r e th a n 3000 i r r a d ia t io n s in th e s e p n e u m a tic tu b e s .

It i s a fa c t th a t so m e e a r l i e r r e a c to r s p o s s e s s e d p n e u m a tic tu b e s but th e y o ften te rm in a te d so m e w h e re o u ts id e th e sh ie ld in g in an a r e a r e m o te fro m the hood sp ace fo r rad io c h e m ic a l p ro c e ss in g . We b rough t th e te rm in a ls of th e p n e u m a tic tu b e s d i r e c t ly in to th e hoods so th a t th e s a m p le cou ld be

98 W.W. MEINKE

sucked fro m th e r e a c to r position next to the c o re d ire c tly into a rad io iso tope hood fo r p ro c e ss in g .

D u rin g th e p a s t s e v e r a l y e a r s , in v is i t in g m any la b o ra to r ie s w hich had c o m p le te d , o r w e re b u ild ing , r e a c to r f a c i l i t i e s , I w as s u r p r i s e d to s e e th a t m any of them s t i l l did not p o s se s s adequate p n eu m atic -tu b e fa c ili t ie s . F u r th e r m o re , s e v e r a l o f th o s e th a t do h av e su c h f a c i l i t i e s u se v e r y bu lky ra b b its a n d /o r te r m in a te th e i r r a b b its a t so m e p la c e o th e r th a n in a hood, so th a t m a n u a l t r a n s f e r s a r e s t i l l r e q u ire d w hen any c h e m ic a l p r o c e s s in g i s to be done.

L e t m e u rg e any g ro u p s w hich m igh t fa l l in to th e s e c a te g o r ie s to co n s id e r s e r io u s ly th e in s ta lla tio n of a p n eu m atic - tu b e fa c ility s im ila r to o u rs . I t is a ty p ic a l US " d e p a r tm e n t- s to r e " ty p e and w as b u ilt fiv e y e a r s ago by th e A irm a t ic C o rp o ra tio n * f o r abou t $ 22 000. I t in c lu d e s fo u r i r r a d ia t io n s ta t io n s a t th e r e a c to r and s ix te rm in a ls o u ts id e the r e a c to r , to g e th e r w ith tim in g m e c h a n ism s fo r au tom atic and m anual o p era tio n , a s w ell as p ro v is io n f o r c o n n e c tin g d if fe re n t o u ts id e te r m in a ls w ith s p e c if ic in s id e t e r m in a ls , and th e b lo w e r to p ro v id e th e v ac u u m f o r th e s y s te m .

P ro b a b ly a m in im a l sy s te m p ro v id in g two pn eu m atic tu b e s w ithout th is v e r s a t i l i ty cou ld be in s ta l le d now fo r $ 10 000 - $ 15 000, w hich is a s m a ll sum of m oney when co m p ared with the to ta l co s t of any r e a c to r fa c ility . The a b ility to in s e r t and r e t r ie v e a la rg e n u m b e r of s a m p le s e a s i ly and ra p id ly m a k e s such a f a c ili ty in d isp e n sa b le and I am s u re th a t you w ill find , a s we a t M ichigan have found, e sp e c ia lly in the e a r ly ,s ta g e s of r e a c to r u tiliza tio n , th a t th e pn eu m atic tu b e s w ill be u sed m uch m o re than a ll th e o th e r fa c ili t ie s of the r e a c to r com bined .

If th e s e p n e u m a tic - tu b e f a c i l i t i e s a p p e a r to be too ex p e n s iv e , i t should be p o ss ib le to fa b r ic a te a le s s e la b o ra te sy s te m locally ,- s im ila r to th e bunny s y s te m w hich w e h av e u se d fo r a n u m b e r of y e a r s to c a r r y s a m p le s f ro m th e rad io c h e m ic a l hood 100 ft down the h a ll to the d e te c to rs [10] . T h is sy stem w as a ls o m o d ified to c a r r y s a m p le s f ro m th e n e u tro n g e n e r a to r to th e d e t e c t o r s [11] . Such s y s te m s c a n be f a b r ic a te d w ith m in im a l su p p lie s and c a n s e r v e th e s a m e fu n c tio n a s th e m o r e e la b o ra te a u to m a t ic a lly - t im e d sy s te m . (One ad d itio n a l fa c ility w orth c o n s id e ra tio n is a pneum atic tube into a th e rm a l co lum n such a s h as been in s ta lle d a t th e T ex a s A and M r e a c to r . )

F o r m o s t w o rk w ith s h o r t - l iv e d r a d io is o to p e s i t i s a ls o d e s i r a b le to h a v e so m e r a p id - m e a s u r in g e q u ip m en t. If ra d io c h e m ic a l s e p a r a t io n s ca n b e m a d e c le a n enough, m e a s u re m e n t of g r o s s d ec ay m ig h t be s a t is f a c to ry . C ounts can be m ade m anually , o r continuous re c o rd in g can be ob ta ined w ith th e m in im a l lo s s of d a ta by th e u se of one of the new p r in tin g s c a le r s , such a s th o s e in th e RID L D e s ig n e r S e r ie s . It: i s , h o w ev er, often m uch s im p le r to u s e so m e ty p e of m u ltic h a n n e l p u lse h e ig h t a n a ly s e r w ith g a m m a s c in ti l la t io n d e te c to rs to m e a su re the sh o r t- liv e d t r a c e r with an a sso c ia ted check of p u r ity .

W h e re th is i s n e c e s s a r y it i s of d e fin ite in te r e s t to h av e m u ltic h a n n e l eq u ip m en t w hich can r e c o rd in fo rm a tio n ra p id ly and co n tin u o u sly . S tandard r e c o r d e r s p r in t 1 - 4 c h a n n e ls p e r se c o n d . A 1 0 0 -c h a n n e l a n a ly s e r w ould th u s b e d ea d f o r 25 - 100 s w h ile p r in tin g ou t, and v a lu a b le d a ta i s lo s t . A

* Airmatic Corporation, 441, Market Street, Saddle Brook, Rochelle Park, New Jersey.


nu m b er of y e a r s ago we solved th is p ro b lem by having a 1 0 0 -ch an n el a n a ly se r w ith tw o m e m o r ie s c o n s tru c te d by th e R a d ia tio n I n s t r u m e n t D ev e lo p m e n t L a b o ra to ry (RIDL) [10] . D u rin g m e a s u re m e n t one m e m o ry r e c o r d s w hile th e o th e r is p r in tin g ou t; th en upon a given s ig n a l th e i r fu n c tio n s r e v e r s e . W ith th is equipm ent we w ere (and s t i l l a re ) ab le to obtain continuous rec o rd in g of s p e c tra of sh o r t- liv e d rad io iso to p es .

A vailab le m o re re c e n tly айе m u ltichannel a n a ly se rs , like th e 400-channel RID L M odel 3 4 - 1 2 , w hich can be s p li t in to h a lv es o r q u a r te r s so th a t s u c c e s s iv e s p e c t r a c a n be re c o rd e d by sh if tin g f ro m one q u a d ra n t to th e n ex t. U n fo r tu n a te ly no a u to m a tic sw itc h in g a r r a n g e m e n ts a r e c o m m e r c ia l ly av a ila b le fo r th is function at the p re s e n t tim e , but we have c o n s tru c te d such an a u to m a tic d e v ic e w ith w hich we ca n ta k e fo u r c o n s e c u tiv e s p e c t r a w ith d e la y s of on ly f ra c t io n s of a se co n d b e tw e en th e m e a s u r e m e n ts .

E ven m o re r e c e n tly m ag n etic tap e re a d -o u ts have been m ade av a ilab le in to w hich th e e n t i r e m e m o ry of a 4 0 0 -ch a n n e l a n a ly s e r can be dûm ped in abou t 5 s , a f te r w hich th e a n a ly s e r is r e a d y f o r m o r e in fo rm a tio n . O th e r r e s e a r c h g ro u p s [12] h av e d e v e lo p e d in s t r u m e n ts w h ich c a n du m p onto ta p e in a f ra c tio n of a second so th a t in the fu tu re we can look fo rw a rd to s y s te m s w hich can m ake co n tin u o u s m e a s u r e m e n ts of s p e c t r a o f s h o r t liv e d ra d io is o to p e s a t afi'y d e s i r e d in te r v a ls .

5. TECH N IQ U ES AND RA DIOCHEM ICAL SEPA RA TIO N S

M any ap p lica tio n s of sh o r t- liv e d rad io iso to p es re q u ire no p o s t- ir ra d ia tio n handling o r m á n ip u la tio n . A ll w ork on the sa m p le s is done p r io r to ir ra d ia tio n . E x a m p le s of su c h a p p l ic a tio n s w ould be r a d ia t io n s o u r c e s o f s h o r t - l iv e d iso to p e s , a s w ell a s n o n -d e s tru c tiv e a c tiv a tio n a n a ly s is . One m igh t ex p ec t is o to p e s w ith h a l f - l iv e s of l e s s th a n one h o u r to b e u s e d in c e r t a in m e d ic a l i r r a d ia t io n p ro c e d u re s , w h ere s tro n tiu m a p p lic a to rs and coba lt n ee d le s a re now u se d . H o sp ita ls w hich o p e ra te in th e v ic in ity of a r e a c to r should su re ly r e - e v a lu a te the p o s s ib le u se of s h o r t- l iv e d iso to p e s to re p la c e som e of th e m o re c o n ta m in a tio n -p ro n e s ta n d a rd te c h n iq u e s . L e t m e s ta te h e r e th a t I believe th is to be one of the m a jo r co n tribu tions of the sm a ll r e a c to r c e n tre s — to p io n e e r in new u s e s fo r s h o r t - l i f e ra d io is o to p e s . S c ie n tis ts and d o c to rs in c o u n trie s which have la rg e iso tope p ro g ra m m e s a re so sa tis f ie d with th e ir Co6° , S r 90 j lia i ' p32 t e tc . th a t th ey r a r e ly need o th e r iso to p e s . H ow ever, the r e s e a r c h r e a c to r c e n tr e p r e s e n ts a unique o p p o rtu n ity to t r y som eth ing new — a s i s in d ic a te d in s e v e r a l o f th e p a p e r s p r e s e n te d a t th is S e m in a r .

In an o th e r a re a , th a t of n o n -d e s tru c tiv e a c tiv a tio n a n a ly s is , th e sam p le i s i r r a d ia te d and th e ra d io iso to p e s induced in th e sa m p le a r e m e a s u re d by g a m m a - ra y s p e c tro m e try a f te r i r r a d ia t io n w ithout d is s o lu tio n o r c h e m ic a l se p a ra tio n . T h ese techn iques a re in w id e-sp rea d use around n u c lea r re a c to rs b e c a u s e of th e i r s im p lic i ty . U n fo rtu n a te ly th e i r u se is l im ite d to o p tim um e lem e n ts and m a tr ic e s , and w id er accep tan ce of th e rap id ac tiva tion ana lysis techn ique r e q u ir e s som e type of fa s t rad io c h em ica l se p a ra tio n .

5 .1 D isso lu tion

Since som e type of rad io c h em ica l m anipu la tion is u sua lly req u ired befo re s h o r t- l iv e d iso to p e s can be u se d , th e d e s ig n of d is s o lu tio n and p ro c e s s in g

100 W.W. MEINKE

s te p s i s a key f a c to r . S tan d a rd a n a ly tic a l d is so lu tio n p ro c e d u re s w hich a re o ften tra d itio n a lly ted io u s and tim e-co n su m in g a re from co n s id e ra tio n e l im in a te d im m e d ia te ly . W e h av e found th a t fu s io n s in n ic k e l c r u c ib le s w ith m a te r i a l s su ch a s so d iu m p e ro x id e fo r ro c k s a m p le s , and a c id ic o r b a s ic le a c h e s fo r b io lo g ica l sa m p le s , p e rm it the d isso lu tio n of such sam ples within a m in u te o r s o . T h is le a v e s m a n y m in u te s a v a ila b le fo r su b s e q u e n t d e c o n ta m in a tio n s te p s , ev e n w ith q u ite s h o r t h a l f - l iv e s .

5 .2 R a d io c h e m ic a l s e p a r a t io n

If th e re is need fo r subsequent p u rifica tio n , sp e c ia l rad iochem ica l p roced u r e s m u s t be ap p lied fo r th e d is s o lv e d s a m p le . H e re ag a in th e c l a s s i c a l a n a ly s t who is in te r e s te d in a y ie ld of 1 0 0 % h a s t r a d i t io n a l ly ta k e n len g th y and te d io u s s te p s . F o r tu n a te ly , in r a d io c h e m is t r y th is q u a n t ita tiv e y ie ld i s no t r e q u ir e d s in c e th e r e a r e w ays o f d e te rm in in g th e y ie ld w ith e i th e r t r a c e r s o r c a r r i e r s . M any q u alita tiv e te s ts which give good decontam ination , but w hich a re not qu ite quan tita tive , a r e ex ce llen t fo r the pu rp o se .

A t th e U n iv e r s i ty of M ich ig an we h av e had m a n y y e a r s e x p e r ie n c e in d e v is in g s h o r t r a d io c h e m ic a l p ro c e d u re s . F ro m th e w ork of SUNDERMAN [13, 14] and DeVOE [15] in th e ev a lu a tio n of th e ra d io c h e m ic a l se p a ra tio n s of a n u m b e r of e le m e n ts , and m o re re c e n tly f ro m th e w ork of SUNDERMAN and c o -w o rk e rs [16] , it a p p e a rs th a t m o st ty p es of rad io c h em ica l se p ara tio n s te p s can be c o m p le ted su c c e s s fu l ly w ith in 15 m in . D iffe re n t ty p e s of p r o c e d u r e s , su c h a s io n ex c h an g e and so lv e n t e x t ra c t io n , o f ten s e r v e to d e co n tam in a te fro m d iffe re n t e le m e n ts . T hus by a p ro p e r com bination of o p tim u m r a d io c h e m ic a l s e p a r a t io n s te p s it shou ld be p o s s ib le to c o m p le te a rad io c h e m ic a l s e p a ra tio n w ithin o n e-h a lf to one hou r w ithout the m any ted ious d ig e s tio n s and re -p re c ip i ta t io n s trad itio n a lly used .

O th e rs in o u r g ro u p have ta k e n a n o th e r ap p ro a ch and have sp e c if ic a lly s tu d ie d th e s e p a ra tio n and u se of c e r ta in s h o r t- l iv e d ra d io iso to p e s such as th e 2 . 3 - m i n s i lv e r , th e 3 . 8 - m in v a n a d iu m , e tc . F o r ea ch ra d io is o to p e w ith a h a l f - l i f e g r e a t e r th a n tw o m in u te s , w hich we have s tu d ied , we have b e e n ab le to d e v e lo p p r o c e d u re s w hich g ive s a t is f a c to r y s e p a r a t io n . T he in d iv id u a l p r o c e d u re s a r e l is te d below , but th e g e n e ra liz a tio n we can m ake f ro m o u r e x p e rien c e is m o re im p o rta n t than any one of th e se e f fo rts -n a m e ly th a t i t i s d e f in ite ly p o s s ib le to m ak e s e p a ra t io n s ro u tin e ly on a l l ty p e s of s a m p le s on t im e s c a le s of a few m in u te s .

A few co m m en ts on the d iffe ren t ty p es of s e p a ra tio n s which a re ava ilab le m ig h t be in o r d e r h e r e . T he old tr a d i t io n a l p re c ip ita t io n and c la s s ic a l e x t r a c t io n p ro c e d u re s w hich p r e t ty w ell c o v e re d th e fie ld in th e e a r ly 1940’s have given way to a m uch m o re h ighly-developed sy stem of o rganic ex trac tio n r e a g e n ts , ion ex ch an g e r e s in s and c h ro m a to g ra p h y m a te r ia ls . A p p lica tio n of e le c t r ic and c e n tr ifu g a l fo rc e s to th e se m ed ia fu rn is h e s o th e r in te re s tin g e ffe c ts . F u r th e rm o re , c e r ta in new se p a ra tio n p ro c e d u re s , such as the s ilv e r e x c h a n g e [13] and a m a lg a m ex c h an g e p r o c e d u re s [17 - 19] , d ev e lo p e d in o u r la b o ra to r ie s , com bine speed w ith high deco n tam in a tio n s and good y ie ld s .

In g e n e r a l , p r e c ip i ta t io n a p p e a r s to be one of th e s lo w e r p r o c e d u re s , in add ition to g iv ing co n s id e ra b le con tam ination th rough occlusion , e tc . — we th e r e f o r e t r y to av o id i t . S o lv en t e x t ra c t io n , on th e o th e r h an d , w ith i t s c le a n s e p a ra t io n of p h a s e s and a g e n e ra l ly ra p id a p p ro a c h to e q u ilib r iu m ,


i s w idely u se d fo r r a d io c h e m is try . One d ifficu lty in so lv e n t e x tra c tio n th a t i s found p a r t i c u la r ly in f is s io n p ro d u c t s e p a ra tio n , is th e te n d e n c y f o r e l e m e n ta l f is s io n p ro d u c t io d in e to fo llow th e o rg a n ic so lv e n t th ro u g h o u t th e p r o c e d u re . An a d d itio n a l s e p a r a t io n s te p m u s t th u s b e u se d f o r c o m p le te d e c o n ta m in a tio n .

T h e s i l v e r ex ch an g e and am a lg a m ex ch an g e p r o c e d u re s ex ten d th e a d v an tag e s of so lven t e x tra c tio n by having two p h a se s of v e ry d iffe re n t d en s ity w hich s e p a ra te v e ry c lea n ly a t the end of the se p a ra tio n .

New tech n iq u es being used in o th e r fie ld s a re su re ly a lso w orth exploring . I t i s d is h e a r te n in g to s e e so m a n y r a d io c h e m is ts s t i l l u s in g o ld , t im e - co n su m in g p r o c e d u r e s , bu t p e r h a p s a g r a d u a l p r o c e s s o f e d u c a t io n w ill convince them of the advantages of the new er tech n iq u es. G en e ra l d isc u ss io n s of th e s e tech n iq u es fo r fa s t ra d io c h e m is try have been co v e red in co n fe ren ce p r e s e n ta t io n [20] , and a lso in th e m o n o g rap h by KUSAKA and M EINK E on R ap id ra d io c h e m ic a l S e p a ra tio n s [3]

TABLE I

T Y P IC A L SH O R T-LIV ED RADIOISOTOPES SEPA R A TED RADIOCHEM ICALLY

Isotope H alf-Life Separation method Reference

Ag1M 2 .3 m in Chloride precipitation or AgCl exchange

[21, 22]

Co®m 10 .5 m in "Oxine" extraction plus reduction to m etal

[23]

C u“ 5 .2 m in Zinc dibenzyl-dithiocarbam ateextraction

[24]

RhM<m 4 .4 min Pyridine extraction [25]

Se7*111 3 .9 min Diisobutyl ketone extraction

[26]

T isl S. 8 min Cupferron extraction [27]V 52 3 .8 min Cupferron extraction [28]

T he s h o r t- liv e d rad io iço to p e s lis te d in T ab le I have been se p a ra te d and handled in conjunction with o u r p ro g ra m m e s of ac tiva tion an a ly s is and n u c lea r c h e m is try a t the U n iv ers ity of M ichigan. T h is l i s t is m ean t to be r e p re s e n ta t iv e r a th e r th an e x h a u s tiv e , s in c e it co n ta in s on ly is o to p e s w hich we h av e had so m e in te r e s t in . T he l i s t d o e s , h o w ev e r, i l l u s t r a te th e fe a s ib i l i ty of h and ling sy s te m s con ta in ing th e s e iso to p e s ra d io c h e m ic a lly . D e ta ils o f th e r a d io c h e m ic a l p r o c e d u re s ca n b e found in th e r e f e r e n c e s l i s te d w ith th e T a b le .

102 W.W. MEINKE

6 . SUMM ARY

O u r e x p e r ie n c e a t B e rk e le y , and now a t M ich igan , h a s p ro v e d th a t i t im p o s s ib le to w ork w ith s h o r t- l iv e d r a d io is o to p e s . W ith ra p id p n e u m a tic - tube s y s te m s to b rin g the sam p le fro m the r e a c to r to hoods in the c h e m is try a r e a , and w ith a u x i l ia ry ra p id t r a n s f e r s y s te m s to t r a n s p o r t s e p a r a te d s a m p le s f ro m th e p ro c e s s in g a r e a to th e m e a s u re m e n t a r e a , th e lim itin g fa c to r h as becom e th e p ro c e s s in g s te p s . O ur s tu d ie s of th is p ro c e s s in g have show n th a t i t is f e a s ib le to o b ta in p u re r a d io is o to p e s f ro m m a n y s a m p le s in a m a t t e r of m in u te s .

R E F E R E N C E S

[1] CALVIN, М ., HELDELBERGER, C . , REID, J .C ., TOLBERT, В. M. and YANKWICH, P .E ., Isotopic Caibon. John Wiley and Sons, N. Y. (1949) 2.

P ] CALVIN, М ., HEIDELBERGER, C . , REID, J .C . , TOLBERT, В. M. and YANKWICH, P .E ., Isotopic Caibon, John Wiley and Sons, N.Y. (1949) 5.

[3] KUSAKA, Y. and MEINKE, W .W ., Rapid rad iochem ica l Separations, N uclear Science Series Report NAS-NS-3104, Off. of T echn. S e rv ., D ept, of C o m m ., W ash., D .C . (D e c ., 1961).

[4] CORYELL, C .D . and SUGARMAN, N ., Radiochemical Studies, McGraw- Hill Book C o ., In c ., New York (1951).

[5] MONOGRAPHS on RADIOCHEMISTRY of the ELEMENTS, N uclear Science Series Repts NAS-NS-3001- 3060 and N A S-N S-3101-3109 , inc l. , Off. o f T echn. S e rv ., D ept, of C o m m ., W ash ., D .C .

[6] WAHLGREN, M. A. and MEINKE, W .W ., "Isom eric State of P la tinum -199", Phys. Rev. 115 (1959) 191.[7] MEINKE, W .W ., GHIORSO, A. and SEABORG, G. T . , "A rtific ial Chains c o lla teral to th e h eav y rad io

a c tiv e Fam ilies” , Phys. Rev. 81 (1951) 782.[8] MEINKE, W .W ., GHIORSO, A. and SEABORG. G .T . , "Further Work on heavy co lla te ra l rad ioactive

C hains", Phys. Rev. 85 (1952) 429.[9] MEINKE, W .W ., "Rapid Separations of Protactinium and Uranium Radioisotopes from Cyclotron bombarded

Thorium N itrate", J. Chem. Phys. 20(1952) 754.[10] MEINKE, W .W ., "P neum atic Tubes Speed A ctivation A nalysis", N ucleonics 17 9 (1959) 86.[11] MEINKE, W .W . and SHIDELER, R. W ., "A ctivation Analysis: New Generators and Techniques m ake it

Routine'*, Nucleonics 20 3 (1962) 60.[12] WAINERDI, R .E ., Texas A and M C ollege, College Station, Texas, private com m unication.[13] SUNDERMAN, D .N . and MEINKE, W .W ., "Evaluation of radiochem ical Separation Procedures. Barium,

Strontium, C alcium ; Silver, Silver by isotopic Exchange; Iron and Lanthanum Hydroxides as Scavengers", Anal. Chem . 29 (1957) 1578.

[14] SUNDERMAN, D. N ., ACKERMANN, I.B . and MEINKE, W .W ., "Radiochemical Separations of Indium ", Anal. Chem . 31 (1959) 40.

[15] DeVOE, J.R- and MEINKE, W .W ., "Radiochemical Separations of Cadm ium", Anal. Chem .^1(1959) 1428.[16] TOWNLEY, C .W . , ELLEMAN, T .S . and SUNDERMAN, D .N . , "R adiochem ical Separation Techniques"

for sho rt-lived Fission Products", Trans. Amer. Nucl. Soc. 5 1 (1962) 194.[17] DeVOE, J. R ., KIM, С. K. and MEINKE, W .W ., "R adiochem ical Separations by A m algam Exchange",

T a lan ta 3 (1960) 298.[18] DeVOE, J .R . , NASS, H .W . and MEINKE, W .W . , " Radiochemical Separation of Cadm ium by Am algam

Exchange” , Anal. Chem . 33 (1961) 1713.[19] RUCH, R .R ., DeVOE, J.R. and MEINKE, W .W ., "R adiochem ical Separation o f Indium by A m algam

Exchange", T a lan ta _9(1962) 33.[20] MEINKE, W .W ., "Techniques for-fast Radiochemistry", Proc. Int. Conf. on Mod. Trends in Activation

Analysis, C ollege Station, Texas (1961) 36.[21] MEINKE, W .W ., USAEC Rept. AECU-3887 (N ov .. 1958).[22] SCHINDEWOLF, U. and WAHLGREN, М ., "The Rhodium, Silver and Indium Content of some chondritic

M eteorites” , G éochim . e t Cosmochim. Acta 18 (1960) 36.[23] KAISER, D. G. and MEINKE, W .W ., "A ctivation Analysis o f tra ce C obalt in Tissue using 10 .5 m inute

C obalt-60m ", T a lan ta 3 (1960) 255.


[24] H0GDAHL, O . , Univ. of M ich. AEC Nucl. Chem . Progr. Rept. 11 (in press).[25] STEELE, E. L. and MEINKE, W. W ., "D eterm ination of Rhodium by therm al neutron A ctivation Analysis

using gam m a-ray Spectrom etry", Analyt. Chim . Acta 26 (1962) 269.[26] KURDDA, R ., Univ. of M ich. AEC Nucl. Chem . Progr. Rept. 11 (in press).[27] KIM, С .K. and MEINKE, W .W ., "T herm al neutron A ctivation Analysis o f T itan ium using 5 .8 -m in u te

T itanium -51 and rapid radiochem ical Separations” , Talanta .(subm itted).[28] MEINKE. W .W ., "A ctiva tion Analysis u tiliz in g fast rad io ch em ica l Separations and portab le neutron

G eneratois", Radioisotopes in the Physical Sciences and Industry, Conf. P ro c ., Copenhagen (1960), IAEA, Vienna, 11(1962) 277.

D I S C U S S I O N

C. TA Y L O R (C h a irm a n ): C ould you s a y so m e th in g on th e m e r i t s o f th e a c c e le ra to r - ty p e n eu tro n g e n e ra to rs th a t a r e now av a ilab le as co m p ared w ith s m a ll n u c le a r r e a c to r s ? In w hat a r e a s w ill th e y be u se fu l, and do you th in k th e y w ill ta k e th e p la c e of s m a ll r e a c to r s in s m a ll c e n tr e s ?

W. W . M EINKE: I am v e ry e n th u s ia s tic about th e n e u tro n g e n e r a to r s . F o r two y e a r s we w orked w ith one of th e e a r ly o n es p ro d u ce d by the T e x a s N u c le a r C om pany and we fee l th a t they have now rea ch ed a point w here they co n s titu te a good ro u tin e la b o ra to ry too l. A ctua lly in the U nited S ta te s about 50 l a b o r a to r ie s a t th e m o m e n t h av e th e s e n e u tro n g e n e r a to r s . T h e r e h a s b ee n r a p id d ev e lo p m e n t in th is f ie ld in th e p a s t y e a r o r so . In F r a n c e th e Sam es Com pany p ro d u ces a s im ila r neu tron g e n e ra to r and I believe in England th e r e i s a n e u tro n g e n e r a to r th a t g iv e s 47r -n e u tro n f lu x e s of th e o r d e r of5 Х Ш 0 o r 10u fa s t n eu tro n s . Reduced to nt|,/cm 2 s tha t is getting n e a r 109 . T h is is s u re ly a s high a s w ith som e of th e e a r ly package r e a c to r s th a t w ere a v a ila b le s e v e r a l y e a r s ago. In o u r e v a lu a tio n of th e n e u tro n g e n e r a to r we w e re ab le to g e t f lu x e s , and th e r e f o r e a c t iv i t ie s , ab o u t a th o u sa n d t im e s le s s than in the pn eu m atic tu b e s of a ty p ic a l r e s e a r c h r e a c to r , such as o u rs a t M ich ig an . V . P . G uinn of G e n e ra l A to m ic s a ls o h a s so m e in te r e s t in g s ta t i s t ic s on w ork done w ith n eu tro n g e n e ra to r s . T h e se n e u tro n g e n e ra to r s a p p e a r to be of m o s t u se fo r the p re p a ra tio n of rad io iso to p es w ith a h a lf- life le s s than one hou r.

I shou ld sa y one of th e d isa d v a n ta g e s a t the m o m e n t i s th a t th e t a r g e t l i f e t im e i s on ly a few h o u r s . H o w ev er, th e r e is a lo t of w o rk g o ing on in te rm s of g e n e ra to r ta rg e t d es ign . The big advantage of the neu tron g e n e ra to r is i ts low co s t ($ 20 0 0 0 ).

I fe e l th a t th e re is a p la c e fo r the r e a c to r and fo r the n eu tro n g e n e ra to r , and ev e n f o r th e is o to p ic s o u rc e , though i t h a s not b ee n m e n tio n e d y e t a t th is S e m in a r .

J . L A L E R E : I sh o u ld l ik e to know w h e th e r M ic h ig a n U n iv e r s i ty h a s a h o sp ita l u s in g s h o r t- l iv e d ra d io iso to p e s fo r m e d ic a l tr e a tm e n t and, if so , a t w hat d is ta n c e f ro m th e r e a c to r .

W. W. M EINKE: We have a la rg e u n iv e rs i ty h o sp ita l, w hich m ak es u se o f so m e 50 с o f I131 and 25 с o f P32 a n n u a lly , b u t th e h o s p i ta l s ta f f h av e no t m a d e u s e of th e s h o r t - l iv e d ra d io is o to p e s a s y e t . In m y v iew , th is is a l in e of ad v a n ce w h e re m a n y of th e c e n t r e s th a t a r e ju s t g e ttin g r e a c to r s ca n b e in th e fo re f ro n t. I am a f ra id th a t m a n y of o u r m e d ic a l peop le in th e U n ited S ta te s a r e so s a t is f ie d w ith w h a t th e y a r e u s in g th a t th e y h a v e no t t r ie d to m ake u se of so m e of the n ew e r is o to p e s . In th is connection I should lik e to r e f e r you to th e p a p e r en titled "A pplica tions of f lu o r in e -18 in b io log ical

104

s tu d ie s w ith s p e c ia l r e f e re n c e to bone and th y ro id physio logy" by M. A n b ar ( th e s e P ro c e e d in g s ) , w h ich I th in k d e s c r ib e s an e x c e l le n t m e d ic a l u s e of a s h o r t - l iv e d is o to p e .

H. SORANTIN: W hat ex p e rien c e have you had w ith polyethylene capsu les and ra f ib its ? We have found at S e ib e rsd o rf th a t th e re a re im p u r it ie s in po ly e th y len e w hich g ive s h o r t- l iv e d iso to p es a f te r i r ra d ia t io n . It depends on the m a n u fa c tu re rs w hat p u r ity one g e ts .

W. W . M EINKE: Y es . O ur s a m p le s a r e se a le d in m e d ic a l-g ra d e p o ly e th y le n e tu b in g (o b ta in a b le in th e U n ited S ta te s f ro m C la y -A d a m s) , w hich i s the p u re s t m a te r ia l th a t we could find. H ow ever, the leve l of t r a c e con tam in a tio n f ro m i r r a d ia t io n a t f lu x e s of a ro u n d 1 0 12 n / c m 2 s i s su c h th a t even th is m a te r ia l i s s t i l l no t p u re enough fo r u s to ta k e a sa m p le d i r e c t ly f ro m th e r e a c to r to o u r m e a su re m e n t equ ipm en t. We have to t r a n s f e r the sam ple to a c le a n c o n ta in e r b e fo re m 'aking m e a s u re m e n ts .

T h e a p p lic a tio n of s h o r t- l iv e d ra d io is o to p e s to a c tiv a tio n a n a ly s is , to t r a c e r e x p e r im e n ts , o r to iso to p e s o u rc e s w ill open up m an y new av en u es of r e s e a r c h . W ith tech n iq u es av a ilab le fo r such rap id p re p a ra tio n of iso topes in a p u re fo rm it now rem a in s fo r the ingenuity of the e x p e rim en te r to develop w ays to u til iz e th e se iso to p es.

PRODUCTION OF SHORT-LIVED RADIONUCLIDES AT THE HAHN-MEITNER INSTITUTE IN WEST BERLIN

F. W. FELIX, D. PIRRWITZ AND E. SZABO DE BUCS HAHN - MEITNER-INS TI TUT FUR KERN FORSC HUNG,

BERLIN, FEDERAL REPUBLIC OF GERMANY


PRODUCTION OF SHORT-LIVED RADIONUCLIDES AT THE HAHN-MEITNER INSTITUTE IN WEST BERLIN. The H ahn-M eitner Institute for Nuclear Research has produced short-lived radionuclides for m edical and sc ien tific purposes in the West Berlin a rea since 1960. Production now covers, th e nuclides com m only used in m ed ical applications, such as N a2s, K*z and Au^98, and other outstanding nuclides such as Cu*<, 2.пв9ш and Fi8; Na24 and K*2are produced by neutron irrad iation of the chlorides and, a fter calib ra tio n , distributed as solid m aterial; Au198 is irradiated in m etallic form, which is suitable for im plantation in cancer therapy; FM is produced by the reaction 0*6 ( t ,n ) and irrad iation of LÍNO3. T he separation of F*8 by ion exchange showed b e tte r results than those usually given in the lite ra tu re . For th e production o f C u64 and Znssm special e lectro ly tic methods have been developed to ex trac t the radionuclides produced by a S z ila rd - C halm ers reac tio n on the phthalocyanines. Both nuclides have found ap p lica tio n in m ed ica l diagnostics.

In the paper details a re given of irradiation facilities and techniques, production methods and apparatus, essay and calibration o f the radionuclides produced and production capacity .

PRODUCTION DE RADIONUCLIDES A COURTE PÉRIODE A L'INSTITUT HAHN-MEITNER DE BERLIN- OUEST. Depuis 1960, l 'In stitu t de recherches nucléaires H ahn-M eitner produit des radionucléides à courte période à usage m éd ical e t scien tifique pour la région de B erlin-O uest. L 'Institu t p répare m a in ten an t des nucléides utilisés couram m ent en m édecine tels que *SNa,-**K et 198Au, ainsi que quelques autres nucléides moins usuels com m e ^ C u , eem zn e t « F . Le sodium -24 e t le potassium -42 sont produits par irradiation neu- tronique des chlorures e t distribués sous forme solide après étalonnage. L 'or-198 est irradié sous form e m éta llique, utilisable pour les im plantations dans le tra item en t du cancer. Le fluor-18 est produit par la réaction WO ( t , n) e t par irradiation de LÍNO3. La séparation de “ F par échange d 'ions a donné de m eilleurs résultats que ceux qui sont hab itue llem en t mentionnés dans les publications spécialisées. Pour la production de MC u e t d e* 9mZn, le i auteurs ont mis au po in t des méthodes électro ly tiques spéciales qui p e rm etten t d 'ex tra ire les radionucléides produits par une réaction Szilard-Chalm ers sur les phtalocyanines. Les deux nucléides ont pu ê tre utilisés pour le diagnostic m édical.

Le m ém oire donne des renseignem ents dé ta illé s sur les installations e t les procédés d 'irrad ia tio n , les méthodes e t appareils de production, l'analyse e t l'é ta lonnage des radionucléides produits e t la cap a c ité de production.

ПРОИЗВОДСТВО КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ В ИНСТИТУТЕ ХАНА-МАЙТНЕРА В ЗАПАДНОМ БЕРЛИНЕ. Начиная с I960 года Институт по йдерным исследованиям Хана-Майтнера производит хороткоживуцие радиоизотопы для медицинских и научных целей для района Западного Берлина. В настоящее время производятся изотопы, применяемые обычно в медицине, такие, как Na25, К42, Au198, а также некоторые менее распространенные, как Cue4, Zne0m и Fie. Na24 и К 42 были получены в результате нейтронного облучения хлоридов и разосланы после калибровки в виде твердых веществ. Au1®8, облученный в форме металла, употребляется для имплантации при лечении рака. Fie получается в результате реакции О1® (t, п) и облучения LiNOa• Отделение F 16 при помощи ионного обмена дало лучшие результаты, чем описываемые обычно в литературе методы. Д ля производства Си®-* и Zn®*™ был разработан специальный метод электролиза для экстрагирования изотопов, полученных при помощи реакции Сцилард-Хальмерса с фталоцианинами. Оба эти изотопа находят применение в медицинской диагностике.

Приводятся подробные данные относительно оборудования и техники облучения, способов производства и аппаратуры, калибровки полученных изотопов и производительной способности.

105

106 F. W. FELIX et al.

PRODUCCION DE RADIONUCLIDOS DE PERIODO CORTO EN EL INSTITUTO HAHN-MEITNER DE BERLIN OCCIDENTAL. En 1960, e l Instituto Hahn-M eitner de investigaciones nucleares, situado en Berlin occidental, em pezó a producir radionúclidos de período corto para fines médicos y científicos. La producción actual com prende núclidos utilizados con frecuencia en m edicina tales como e l 25Na, 42K, u s a u , así como e l MCu, 69mZ y 18F. El 24Na y e l se obtienen por irradiación neutrónica de los cloruros y , una vez calibrados, se sum inistran en forma de sólidos. El i 98 Au se obtiene por irradiación del m etal y puede em plearse d irectam en te para im plantaciones en e l tra tam ien to del cáncer. El 18F se obtiene por la reacción 160 ( t, n) y por irrad iac ión del LiNOs. La separación del 18 F por in tercam bio iónico dio resultados más favorables que los que se citan generalm ente en la bibliografía. En la producción de ®*Cu y e®m Zn, se han perfeccionado métodos electrolíticos especiales para extraer los radionúclidos obtenidos por una reacción de Szilard-Chalmers aplicada a ftalocianinas. Ambos núclidos han encontrado aplicaciones en el diagnóstico médico.

La m em oria da de ta lles sobre las instalaciones de irrad iación y las técnicas em pleadas, los métodos de producción y los aparatos, e l análisis y la calib ración de los radionúclidos obtenidos, así com o sobre la capadidad de producción del c itado Instituto.

1. INTR O D U CTIO N

The H ah n -M eitn e r In s titu te fo r N u c le a r R e s e a rc h (HMI) w as founded in 1957 an d in a u g u ra te d in 1959. A s th e In s itu te h as th e only r e a c to r in W est B e r l in it w as p la n n ed to e s ta b l is h a s e r v ic e p ro v id in g in s t i tu te s , h o sp ita ls an d o th e r la b o ra to r ie s w ith s h o r t- l iv e d ra d io n u c lid e s . The p roduction s t a r t e d on a s m a l l b a s is w ith a g ro u p of two s c ie n t is ts and th r e e o r fo u r te c h n ic ia n s . R a d io n u c lid es have b ee n d e l iv e re d r e g u la r ly s in c e 1961, a s T ab le I show s

TABLE I

D E L IV E R IE S O F RADIONUCLIDES BY THE HAHN-M EITNER INSTITU TE(m e)

Period Na24 Ke Cu“ Au1>s

January - June, 1961 9 .6 10.4 - -

June - D ecem ber, 1961 - - 14 -

January - June, 1962 1.0 1.0 8 .9 2032

T h e ch o ic e of ra d io n u c lid e s fo r p ro d u c tio n is m a d e p a r t ly a c c o rd in g to th e a v a ila b le f a c i l i t i e s and p a r t ly in c o -o p e ra tio n w ith th e in te re s te d la b o ra to r ie s . T h e m a x im u m p ro d u c tio n c a p a c ity h a s no t y e t b ee n r e a c h e d an d ex p a n s io n is to be e x p e c te d in th e n e a r fu tu re .

2. F A C IL IT IE S F O R NUCLIDE PRO DU CTIO N

A ll i r r a d ia t io n s a r e p e r f o rm e d in th e BER ho m o g en eo u s w a te r b o i le r r e a c to r c o n s tru c te d by A to m ic s In te rn a t io n a l , C anoga P a rk , USA. T he r e a c to r h a s a m a x im u m p o w er of 50 kW an d a m a x im u m th e r m a l f lu x of1 .3 X ^ 1 0 i2 n c m -2 s "1 . T h e s a m p le s a r e i r r a d i a t e d m a in ly in th e c e n t r a l c h a n n e l and in a c h a n n e l p a s s in g th e c o re ta n g e n tia lly . R e m o te -c o n tro lle d sa m p le c h a n g e rs a r e p ro v id e d fo r load ing and unloading ; bo th ch an n els have b e e n d e s ig n e d an d b u ilt a t th e HMI by M r . G. Ja c o b (R e a c to r P h y s ic s D ep a r tm e n t) . F ig u re 1 show s s c h e m a tic a lly th e c e n tr a l c h a n n e l a r ra n g e m e n t .

a 98

0

Fig-1

Irradiation fac ility for the BER C entral Channel

SHO

RT-LIVED

RA

DIO

NU

CLIDES

AT THE

HA

HN

-MEITN

ER IN

STITUTE

107

108 F. W. FELIX et al.

I t c o n s is t s of th r e e m a in p a r t s : th e h e a v y c o n c r e te s h ie ld o u ts id e th e r e a c to r fo r th e sa m p le t r a n s p o r t sy s te m , th e lo a d -u n lo ad m e ch a n ism , and the p a r t in s id e th e r e a c to r w ith sh ie ld in g and m o d e ra tin g m a te r ia l su rro u n d in g th e s a m p le t r a n s p o r t tu b e . A to ta l of fo u r s a m p le s ca n a r b i t r a r i l y b e e x changed by re m o te c o n tro l o r m a n u a lly in c a s e of c u r r e n t fa i lu re . A ll m o v ab le p a r ts can be r e p la c e d w ithout d ifficu lty . As m o d era tin g m a te r ia l fo r the p a r t in s id e th e c e n t r a l c h a n n e l, p o ly e th y le n e h a s b e e n u s e d s u c c e s s fu l ly . A s th e p o ly e th y le n e a c ts o n ly a s a f i l l in g m a te r i a l an d h a s no m e c h a n ic a l fu n c tio n s , i t w as a s s u m e d th a t r e p la c e m e n t w ould be n e c e s s a r y only a f te r so m e 1018 n c m -2 to ta l n e u tro n d o se . H o w ev er, e x p e r ie n c e sh o w s th a t it w il l h a v e a n ev e n lo n g e r l i f e t im e .

The sa m p le s a r e i r ra d ia te d in s ta n d a rd alum in ium c o n ta in e rs , developed a t th e R 1 r e a c to r , AB A to m e n erg i, S tockho lm (Sw eden). T he s a m p le s a r e u s u a lly t r a n s p o r te d by a r e m o te - c o n tr o l le d p n eu m atic s y s te m in to a s m a ll c e l l of 5 cm le a d eq u iv a len t and equipped w ith b a l l- jo in t m a n ip u la to rs . T his f a c ili ty h as a lre a d y b een d e sc r ib e d in d e ta il [1]. L ow er a c tiv itie s a re handled in tw o fu lly -eq u ip p e d ra d io c h e m ic a l la b o ra to r ie s .

3. TH E PRODUCTION PROGRAMME

It is o b v io u s th a t th e p r o g ra m m e of p ro d u c tio n h a s to b e a r a th e r r e s t r ic te d one, if the i r ra d ia t io n fa c ili ty c o n s is ts of a s m a ll r e s e a r c h r e a c to r . A t th e HMI an a r b i t r a r y u p p e r l im it fo r th e h a lf - lif e of p ro d u ce d n u c lid es is f ix e d a t 24 h. N e v e r th e le s s , ex c ep tio n s fo r s p e c ia l c a s e s a r e m ad e , a s fo r e x a m p le , fo r Au 198 (see below ).

Up to th e p r e s e n t t im e th e p ro d u c tio n s e r v ic e a t th e HM I c o n s is ts in sa m p le p re p a ra tio n , i r r a d ia t io n and c h e m ic a l tr e a tm e n t a f te r i r ra d ia t io n in s p e c ia l c a s e s and r e la t iv e c a lib ra t io n . P re p a ra tio n of s te r i l iz e d o r iso to n ic so lu tio n s , s y n th e s is of la b e lle d com pounds and ab so lu te m e a s u re m e n ts a r e ex c lu d e d .

4 . TECHNIQUES F O R S P E C IA L RADIONUCLIDES

4 . 1. N a 24

N a 2 4 is p ro d u c e d fo r th o se c u s to m e rs who a r e in te r e s te d only in s m a ll a m o u n ts of a c tiv i ty fo r t r a c e r w o rk . It i s p ro d u c e d in th e u s u a l w ay by i r r a d ia t io n of N aC l o r N a2 C 0 3 .

4 .2 . K42

T h e s a m e a s fo r N a 2 4 . --

4. 3 . Au 198

A s p e c ia l v e r t i c a l c h a n n e l in th e r e a c to r is r e s e r v e d fo r a c tiv a tio n of go ld se e d s fo r th e n u c le a r m e d ic in e d ep a rtm en t of th e Rudolf V irchow h o sp ita l , B e rlin . A s to c k of se e d s is i r ra d ia te d continuously in the r e a c to r and on

SHORT-LIVED RADIONUCLIDES AT THE HAHN - MEITNER INSTITUTE 109

r e q u e s t in d iv id u a l s e e d s a r e w ith d raw n , c a l ib ra te d and d e l iv e re d in a s h o r t t im e . T he ro u tin e r e a c to r c y c le in d u c e s in th e s e e d s (about 23 m il l ig r a m s p e r se e d ) su f f ic ie n t a c c u m u la te d a c tiv i ty fo r m e d ic a l a p p l ic a tio n s , i. e . 18 m i l l i c u r i e s p e r s e e d m o r e o r l e s s in d e p e n d e n tly of th e d ay of th e w e e k .

4 .4 . C u 6 4

4. 4 . 1. S z i la r d - C h a lm e r s s e p a r a t io n

C o p p e r-6 4 i s n o rm a lly p ro d u c e d fo r m e d ic a l d ia g n o s is by th e S z ila rd - C h a lm e r s p r o c e s s on C u -p h th a lo c y a n in e (C uP C ) [2, 3, 4, 5]. C o m m e r c ia l C u P C is p u r if ie d by r e p e a te d a lc o h o l e x t ra c t io n an d c r y s ta l l i z a t io n out of c o n c e n tra te d s u lp h u r ic a c id . F r e e Cu is d e te rm in e d c o lo r im e t r ic a l ly w ith b e n z id in e . T he ro u tin e p r o c e d u r e fo r < 10 m e Cu64 f i. e . f o r d e l iv e r y of1 -4 m e C u 6 4 , i s a s fo llo w s :

I r r a d ia t io n of 20 g C uP C p o w d e r in tw o p o r t io n s fo r 1015 n c m -2 e x t r a c t io n in a s im p le a p p a ra tu s , F ig . 2, m oun ted in a sh ie ld e d c e l l and co m -

SZILARD-CHALMERS separation o f C u-64

p le te ly h an d led by b a l l - jo in t m a n ip u la to rs . T he C u 6 4 i s e x t ra c te d fo r 2h in 4 N b o ilin g H2 SO4 to g e th e r w ith 1 m l o c ta n o l a s w e ttin g a g e n t. F i l t r a t io n and r in s in g w ith d is t i l le d w a te r on a G 3 B üchner type funnel. A s m a ll p a r t of th e 3 3 0 -m l f i l t r a t e is u se d fo r d e te rm in a tio n of th e sp e c if ic a c tiv i ty and th e r a d io c h e m ic a l p u r ity .

4 . 4. 2. New p u r if ic a tio n m eth o d fo r th e S z ila rd -C h a lm e rs e x tra c t

F o r th e c o n c e n tra tio n of th e C u 6 4 and th e e l im in a tio n o f o rg an ic ra d io - ly t i c a l d e c o m p o s itio n p ro d u c ts an e le c t r o ly t ic a l p ro c e d u re h a s b e e n in t r o d uced :

110 F. W. FELIX e t al.

T he m a in p a r t of th e f i l t r a t e is t r a n s f e r r e d in to a b e a k e r and e l e c t r o ly s e d o v e rn ig h t fo r 16 h a t 80°C (anode: f i s h e r - ty p e p la tin u m n e t; ca th o d e : p la tin u m w ire , v o ltag e : 2 V). The b èa k e r is p laced in a heavy s te e l con ta ine r, ac tin g p a r t ly a s a ra d ia tio n sh ie ld and p a r t ly a s a th e rm o s ta t .

T h e Cu64 is d is s o lv e d in a v e r y s m a ll am o u n t of HNO3. T he c u s to m e r e v a p o ra te s th is so lu tio n to d ry n e s s and t r a n s f o r m s th e r e s id u e in to a fo rm su ita b le fo r m e d ic a l ap p lic a tio n .

U su a l d a ta : y d o se a f t e r i r r a d ia t io n :T o ta l Cu c o n te n t:S z i la r d C h a lm e rs y ie ld : F r e e C u++ a f te r e x t r a c t io n : Cu64 e n r ic h m e n t :

1 0 0 m r / h a t 1 0 c m 2 2 0 0 m g

50%2 - 8 m g 500 - 1000

Y ie ld f ro m e l e c t r o l y s i s : 50 - 80%.

To sh o rte n th e p ro c e d u re tim e a flow e le c tro ly s is techn ique is u n d er developm en t.

4. 5. Zn69m

Z in c-6 9 m w ill be u se d fo r p u rp o se s s im ila r to Cu**4 ; it is a lso p roduced b y a S z i la r d - C h a lm e r s p r o c e s s . A s no c o m m e r c ia l Zn p h th a lo c y a n in e is a v a ila b le , ZnPC is sy n th e s iz e d f ro m p h th a lic ac id d in it r i le and Z n[2], F r e e Zn is d e te rm in e d c o lo r im e tr ic a lly by zincone .

T h e i r r a d ia t io n , e x tra c tio n and e le c t ro ly s i s p r o c e d u re s a r e th e s a m e a s fo r Cu64 , but ro u tin e p ro d u c tio n is no t y e t u n d e r ta k e n .

4 .6 . F18

F o r b io lo g ic a l t r a c e r s tu d ie s g a s e o u s la b e lle d H F is n eed ed . F o r th is p u rp o se a c o -p re c ip ita tio n m ethod se e m s m o st convenient [6 , 7 ] .E ight g ram s of LÍNO3 a r e m e lte d in a q u a r tz v ia l and coo led to ge t m ax im um su rfa c e and m in im u m th ic k n e s s . A f te r i r r a d ia t io n F 18 i s c o - p r e c ip i ta te d w ith B a S 0 4

out of 5 0 -m l so lu tio n w ith 8 . 5 -m l 0.1 N (NH4)2S04 and 9 m l 0.1 N Ba(N03>2. T h e s o lid p ro d u c t i s d e l iv e re d an d th e c u s to m e r d ev e lo p s H FI8 by add ing C aF 2 c a r r i e r a n d H 2 S 0 4 .

Y ie ld s : T o ta l th e r m a l n e u tro n d o se :■ ' T o ta l F18 p ro d u c e d :

C o - p r e c ip i ta t io n y ie ld :

5 . C A L IB R A T IO N O F T H E R A D IO N U C LID ES P R O D U C E D

The ra d io n u c lid e s p ro d u ced a r e u su a lly m e a su re d w ith a c a lib ra te d io n iz a tio n c h a m b e r co n n e c te d to a v ib ra t in g r e e d e le c t r o m e te r . W h ere l e s s a c c u r a c y is r e q u i r e d , th e a c tiv i ty is c a lc u la te d f ro m th e i r r a d ia t io n d a ta . T h e r a d io c h e m ic a l p u r i ty i s d e te r m in e d by fo llo w in g th e h a l f - l i f e an d by s in g le o r m u lt ic h a n n e l p u ls e h e ig h t a n a ly s i s .

7 X 1015 n cm -2 2 . 9 - 4 /¿c /g L ÍN O 3

45 - 58%

SHORT-LIVED RADIONUCLIDES AT THE HAHN-MEITNER INSTITUTE 111

6 . F IN A N C IA L A S P E C T

A s th e HMI is a g o v e rn m e n t in s t i tu te , i t is n e c e s s a r y fo r c u s to m e rs to fo llow a p r ic e ta r i f f fo r ra d io n u c lid e s . A p r e l im in a r y t a r i f f h as b ee n e s ta b lis h e d th is y e a r [8 ] in ac co rd an c e w ith w hich som e rad io n u c lid e s p roduced by s im p le i r r a d ia t io n , w ithout any c h e m ic a l a f te r - t r e a tm e n t , a r e d e l iv e re d a t f ix e d p r i c e s . F o r e x a m p le , th e c o s t of Na24 is 30 DM fo r th e f i r s t 10 m e and 3 DM fo r each ad d itio n a l m e . T h ese fixed p r ic e s a r e som ew hat below the u s u a l E u ro p e a n c o m m e rc ia l p r i c e s . A s th e HMI o f fe rs th e s e ra d io n u c lid e s w ith no a f t e r - t r e a tm e n t , th is is r e a s o n a b le . P r i c e s f o r r a d io n u c lid é è d e m anding s p e c ia l t r e a tm e n t a r e c a lc u la te d on an in d iv id u a l b a s is , tak in g into accoun t th e c o s ts of m a te r ia l , lab o u r and o v e rh e ad s . As ex p e rien c e is gained th e s e p r ic e s w ill a lso be t ra n s fo rm e d into fixed ones.

The p r ic e s a r e re d u c e d fo r public sc ie n tif ic in s t itu te s and h o sp ita ls and even m o re so fo r b a s ic r e s e a r c h p u rp o se s a t the B e rlin u n iv e rs i t ie s .

A C K N O W L E D G E M E N T S

T he a u th o rs a r e g r a te fu l to M r. S. A lex and M r. W. W in ze r fo r sk ilfu l te c h n ic a l a s s is ta n c e in a l l th e e x p e r im e n ta l w ork .

R E F E R E N C E S

[1] FELIX, F . , "PrSparatelager’', Atomwirtschaft 4(1959) 115.[2] HERR, W. und GOTTE, H . Gewinnung eines praktisch trâgerfreien Radiokupferprâparates” , Z .N aturf.5a

(1950) 629.[3] PAYNE, B .R ., SCARGILL, P. and COOK, G . , "The Szilard-Chalmere Reaction in m etal Phthalocyanines",

Radioisotopes in Scientific Research II ( 1958) 154.[4] SHARP, R. A. and SCHM ITT, R . , Studies o f th e S zilard -C halm ers Processes, GA-910 (1959).[5] APERS, D. I. and CAPRON, P . , C hem ica l Consequences o f nuc lear Recoil in Solids, C EN T/32 Prague

(1960). ' .[6] MÜNZE, R.,, "D ie Isolierung k le inster Fluoridm engen durch M itfâ llung", K ernenergie 3 (1960) 429.[7] MÜNZE, R. und BARANIAK, L ., "Die Herstellung des trâgerfreien N aB F", K em energie 3(1960) 989.[8] V orlâufige Entgeldordnung des Sektors K em chem ie im HMI. A m tsb latt für Berlin Hi (1962) 221.

D I S C U S S I O N

H. SORANTIN: I u n d e r s ta n d th a t in th e p r e p a ra t io n of A u i9 8 you a r e k eep ing a s to c k of Au s e e d s p e rm a n e n tly i r r a d ia te d : d id you d e te rm in e th e r a t io of A u 198 to A u 199 ?

F . F E L IX : No. T he f lu x is to o low to p ro d u ce a m e a s u ra b le am ount of A u i9 9 .

B. R . PA Y N E (IA EA ): C o u ld you q u o te th e e n r ic h m e n t f a c to r f o r th e co p p e r ph th a lo cy an in e u n d e r th e ir ra d ia t io n condition? By e n ric h m en t fa c to r I m e a n th e r a t i o of th e s p e c if ic a c t iv i ty of th e f in a l p r o d u c t to th a t of th e in i t i a l m a t e r i a l b e fo re s e p a r a t io n .

F . F E L IX :, T h e i r r a d ia t io n f lu x is 1 0 n an d th e e n r ic h m e n t f a c to r i s ab o u t 500 to 1000.

112 F. W. FELIX e t al.

B. R . PA Y N E : How long a n i r r a d ia t io n ?F . F E L IX : I th in k , 6 h .B. R . PA Y N E: I b e lie v e you w ill g e t a m u ch h ig h e r e n r ic h m e n t f a c to r

u n d er s im ila r i r ra d ia t io n conditions if you u se a m ild e r m ethod of e x tra c tio n . You w ill f in d th e s e p a r a b le y ie ld to b e ab o u t 55% if you s im p ly r e - f l u x th e i r r a d ia te d m a te r ia l fo r 2 h b e fo reh a n d w ith 4 N su lp h u ric ac id . Y our m a x im um e n ric h m e n t f a c to r , if I r e m e m b e r c o r re c tly , shou ld then be som eth ing lik e 2 0 0 0 .

M . DOUIS: You m en tio n th e u se of N aC l a s à ta rg e t fo r th e p re p a ra tio n of sod iu m -2 4 . Do you not th ink th a t seco n d a ry re a c tio n s on the ch lo rin e , (n, p) o r (n, a) r e a c tio n s , m igh t p ro d u ce o th e r ra d io iso to p e s w ith lo n g e r h a lf- liv e s , su ch a s c h lo r in e - 36 o r p h o sp h o ru s-3 2 ?

F . F E L IX : T he h o sp ita l w here we w ork p r e f e r s to u se sodium ca rb o n ate f o r p ro d u c in g Na24 , b u t s o m e tim e s c u s to m e rs sp e c ify N aC l. As th e i r r a d ia t io n t im e is v e r y s h o r t no d is tu rb in g a m o u n ts of P32 a r e p ro d u c e d .

C. TAYLOR (C hairm an): I w as in te re s te d to h e a r th a t you keep a s to ck of go ld se e d s in th e r e a c to r . T h is m e an s th a t you w ill be supplying th e sam e s tr e n g th of s e e d to e v e ry u s e r . We find th a t d if fe re n t h o s p ita ls dem and d iff e r e n t se e d s tre n g th s and so we c a r r y out s e p a r a te ir ra d ia t io n s . И we could p e r s u a d e th e m a l l to u s e th e s a m e s tr e n g th , i t w ou ld s a v e an aw fu l lo t of b o th e r .

F . F E L IX : We h av e on ly one h o s p i ta l to su p p ly .

THE SCOTTISH RESEARCH REACTOR CENTRE AND ITS FACILITIES FOR THE PRODUCTION AND

EXPLOITATION OF SHORT-LIVED RADIOISOTOPES

A. WARDTHE ROYAL COLLEGE OF SCIENCE AND TECHNOLOGY, GLASGOW, SCOTLAND


THE SCOTTISH RESEARCH REACTOR CENTRE AND ITS FACILITIES FOR THE PRODUCTION AND EXPLOITATION OF SHORT-LIVED RADIOISOTOPES. The Scottish Research Reactor C entre is now under construction and w ill be com pleted and in operation by the summer of 1963. The reactor is 100 kW of the tank type with water cooling and w a ter/g raph ite m oderation using enriched U 235 fuel. The experim ental facilities include a large therm al colum n, a large shield experim ent water tank and a radioisotope production fac ility with transfer rabbit tubes. There a re e ffec tive ly three through tubes in the cen tra l core; one through tube in the therm al co lum n, several sm all cen tra l vertica l stringers and one six -inch square v e rtica l stringer penetrating to the centre of the core. Many horizontal stringers pass through the therm al colum n, the centra l one penetrating to within one inch of a fuel tank.

The reactor facilities are supported by a wide variety of ad jacent sm all laboratories. These include hot source handling and preparation facilities , changing rooms, e lec trica l and m echanical workshops, darkrooms, m icrocurie laboratories, an im al house, biological and chem ical laboratories, low-background counting room, lecture theatre and a library.

I t is expected th a t the research w ill extend over m any scien tific and technological disciplines; a good proportion of the work w ill involve short-lived radioisotopes and typ ica l projects are described.

LE RÉACTEUR DE RECHERCHE ECOSSAIS ET SES INSTALLATIONS POUR LA PRODUCTION ET L'EXPLOITATION DES RADIOISOTOPES A COURTE PERIODE. Le réacteur de recherche écossais ac tu e llem en t en construction sera term iné e t entrera en service pendant l 'é té 1963. I l s 'ag it d*un réacteur-piscine de lOOkW à u ranium -235 en rich i, refro id i à l 'e a u e ti ra len ti à l 'e a u e t au g raphite . Les insta llations expérim entales com prennent une grande colonne therm ique , un grand réservoir d 'e a u b lin d é pour les expériences , e t une insta llation de production de radioisotopes m unie de tubes de transfert à fonctionnem ent pneum atique. Trois tubes traversent le cœur cen tra l, un autre traverse la colonne therm ique. 11 existe eniin plusieurs petites g o u ttières verticales centrales e t une gou ttière vertica le à section carrée de 15 cm de cS té , qui pénètre jusqu'au centre du cœ ur. De nombreuses gouttières horizontales traversent la colonne therm ique, la gouttière centrale pénétrant jusqu'à 2 ,5 cm d 'un réservoir de combustible.

Le réacteur est doté de tou te une série de petits laboratoires ad jacen ts: installations de m anutention e t de préparation de sources de hau te a c tiv ité , vestiaires, a te liers d 'é le c tr ic ité e t de m écanique, cham bres noires, laboratoires pour activ ités de 1*order du m icrocurie, salle pour anim aux, laboratoires de bio logie e t de ch im ie , sa lle de com ptage à fa ib le bruit de fond»am phithéâtre e t b ibliothèque.

On pense que les recherches s 'é tendron t à de nombreuses disciplines scientifiques e t technologiques; une grande partie du trav a il portera sur les radioisotopes à courte période; l'au teu r décrit quelques projects caractéristiques.

ШОТЛАНДСКИЙ ИССЛЕДОВАТЕЛЬСКИЙ РЕАКТОРНЫЙ ЦЕНТР И ЕГО ТЕХНИЧЕСКИЕ СРЕДСТВА ДЛЯ ПРОИЗВОДСТВА И ИСПОЛЬЗОВАНИЯ КОРОТКОЯИВУШХ РАДИОИЗОТОПОВ. В настоящее время ведется строительство Шотландского исследовательского реакторного центра, который вступит в строй к весне 1963 года. Установка представляет собой реактор бакового типа мощностью 100 квт с водяным охлаждением и водографитовым замедлителем при использовании обогащенного топлива (уран299). Экспериментальное техническое оборудование включает большую тепловую колонну., большой водяной бак с защитой, а также установку для производства радиоизотопов с пневматическим транспортером. В центре активной зоны имеются три сквозные трубы; имеется также одна сквозная труба в тепловой колонне,а также несколько небольших центральных вертикальных стрингеров и один вертикальный стрингер сечением в дкймов, доходящие до центра активной зоны реактора. Много горизонтальных стрингеров проходит через тепловую колонну, причем центральный стрингер проходит на расстоянии одного дкйма от топливного бака.

113

114 A. WARD

В дополнение к реакторному техническому оборудование имеется множество небольших лабораторий. Эти лаборатории включают оборудование для получения горячих источников и работы с ними, а также комнату для переодевания, электрические и механические мастерскиеj темные комнаты, лаборатории для работы с микрокюриевыми количествами, помещение для животных, биологическую и химическую лаборатории, счетную комнату с низким уровнем фона, лекционный зал и библиотеку.

Предполагается, что исследования будут касаться многих научных и технических дисциплин: большая часть работы будет связана с использованием короткоживущих радиоизотопов. Описываются типовые проекты.

EL CENTRO DEL REACTOR DE INVESTIGACION DE ESCOCIA Y SUS INSTALACIONES PARA LA PRODUCCION Y EMPLEO DE RADIOISOTOPOS DE PERIODO CORTO. El centro de l reactor de investigación de Escocia se encuentra en construcción, calculándose que entrará en servicio en e l verano de 1963. El reactor de tipo tanque tiene una potencia de 100 kW, es refrigerado por agua y moderado por agua y grafito; e l com bustib le es uranio enriquecido e n e l isótopo s ssu . Las instalaciones experim entales consisten en una gran colum na té rm ic a , con tanque de agua b lindado de grandes dim ensiones y una insta lación de producción de radioisótopos con tuberías de transporte neum ático. El cuerpo central es atravesado por tres tubos, la columna té rm ica , por uno; adem ás, existen varios pequeños dispositivos centrales de acceso vertical y otro dispositivo de acceso de sección cuadrada , de 6 pu lgadas, que penetra ve rtic a lm e n te hasta e l cen tro de l cuerpo del reacto r. Muchos otros dispositivos de acceso horizontal atraviesan la colum na té rm ica , y e l del centro del cuerpo penetra hasta 1 pulgada de los tanques de com bustible.

El cen tro com prenderá un gran núm ero de locales auxiliares en los que se insta larán dispositivos para m anejar y preparar fuentes de a lta a c tiv id ad , vestuarios, ta lleres e léctricos y m ecánicos, cuartos oscuros, laboratorios para trabajar con actividades del orden del m icrocurie, criaderos de anim ales, laboratorios b iológicos y quím icos, lo c a l de recuen to de b a ja activ idad de fondo, sala de conferencias y b ib lio teca .

Se espera que las investigaciones abarquen muchos cam pos científicos y tecnológicos. Gran pa rte de los trabajos se e fectuarán con ayuda de radioisótopos de período corto. La m em oria describe algunos de los proyectos más característicos.

1 . IN TR O D U C TIO N

1 .1 . T he S co ttish R e s e a rc h R e a c to r C e n tre* h a s been des igned to m ee t the n ee d s of S co tland f o r education , r e s e a r c h and developm ent.1 .2 . In m any w ays the C e n tre is unique in covering such a wide field; p hysic i s ts , c h e m is ts , m e ta l lu rg is ts , b io lo g ica l and m e d ica l, and o th e r r e s e a r c h and dev e lo p m en t w o rk e rs w ill u se the C e n tre fo r a w ide v a r ie ty of p ro je c ts .1. 3. F o r th is r e a s o n th e C e n tre m ay be p a r t ic u la r ly in te r e s t in g to th o se in o th e r c o u n tr ie s who w ish to have a v e r s a t i le and econom ic m e an s of c a r r y ing out such r e s e a r c h and developm ent p ro je c ts .

2. SITING

2 .1 . T h e ch o ice of a re a lly su ita b le s ite is the f i r s t c o n s id e ra tio n . In S co tla n d ,o n e th i r d of th e p o p u la tio n of o v e r f iv e m il lio n l iv e in one p e r c e n t of th e a r e a in a h e a v ily - in d u s tr ia liz e d reg io n ex tending fo r about 30 km around G lasgow .2. 2. L u ck ily s im i la r c o n s id e ra tio n had a l re a d y le d to th e e s ta b lish m e n t of the N a tio n a l E n g in e e rin g L a b o ra to ry a t E a s t K ilb rid e , 15 km e a s t of G lasgow , to w a rd s E d in b u rg h , a n o th e r m a jo r c e n tr e of ed u c a tio n , r e s e a r c h an d in

* T he D irector o f th e Scottish Reactor C en tre is Dr. H. Wilson and i t is expected th a t the C entre will b e in operation by June* 1963.

THE SCOTTISH RESEARCH REACTOR CENTRE 115

d u s tr ia l a c tiv ity . Room w as a v a ila b le w ithin the la rg e g ro u n d s of th e N ational E n g in e e r in g L a b o ra to ry f o r th e co m p le te in s ta lla tio n of th e R e a c to r C e n tre .2. 3. T h e in s t itu tio n s c o n c e rn e d w ith o p e ra tin g th e C e n tre a r e th e fo u r t r a d it io n a l S c o tt i s h U n iv e r s i t ie s of G lasg o w , E d in b u rg h , S t. A n d re w s an d A b erd een and th e R oyal C o llege of S cience and T echnology in G lasgow , w hich h a s r e c e n t ly b ee n g ra n te d U n iv e rs i ty s ta tu s . E d in b u rg h , S t. A n d re w s and A b e rd e e n a r e a b o u t 50, 150 an d 250 k m f ro m E a s t K ilb r id e w ith is o to p e t r a n s f e r t im e s by f a s t c a r of about one h o u r, two h o u rs and fo u r h o u rs r e s p e c tiv e ly . In th e c a s e of A b e rd e e n th e e x is te n c e of a i r p o r t s , a t R e n fre w , n e a r G lasgow , and D yee, n e a r A b erd een , re d u c e s the t r a n s f e r tim e to about tw o h o u r s a llo w in g f o r c a r t r a n s p o r t to an d f ro m a i r p o r t s . T h e t r a n s f e r t im e to G lasg o w i s a b o u t h a lf a n h o u r .2 .4 . T h e se t r a n s f e r t im e s a r e one re a so n fo r hav ing a com ple te ly se lf co n ta in ed R e a c to r C e n tre w ith f a c il i t ie s fo r the explo ita tion of sh o r t- liv e d r a d io iso to p es a s w ell a s handling and p ro c e ss in g equipm ent.

3. BUILDINGS

3 .1 . F ig u re 1 show s a p lan view of the two build ings co m p ris in g the R e ac to r C e n tre . T h e two b u ild in g s a r e jo in ed by a s h o r t en c lo se d c o r r id o r r e f e r r e d to a s th e L in k .

The Scottish Research Reactor Centre

116 A. WARD

3 .2 . T h e R e a c to r i t s e l f i s s i tu a te d in th e c e n t r e o f th e R e a c to r H a ll and p n e u m a tic t r a n s f e r tu b e s ( ra b b it tu b e s) ru n f ro m th e c e n t r a l re g io n of the r e a c to r c o re to two Hot L a b o ra to r ie s in th e sa m e bu ild ing . M a te r ia l i r r a d i a te d in th e r e a c to r ca n be t r a n s f e r r e d a u to m a tic a lly to th e s e H ot L a b o r a to r i e s th ro u g h th e ra b b it tu b e s in about ha lf a second . T he Hot L a b o ra to r ie s a r e d es ig n ed to h and le and p ro c e s s m a te r ia l w ith a c tiv ity le v e ls up to about 1 0 0 m e of g a m m a r a d ia t io n , w h ich is a ro u n d th e m a x im u m a c t iv i t ie s e n c o u n te re d in th e i r r a d ia t io n of o n e - g r a m s a m p le s of m o s t e le m e n ts in th e m a x im u m th e r m a l n e u tro n flu x of 1 0 1 '2 n / c m 2 s .

One of the Hot L a b o ra to r ie s is m ain ly co n c ern ed w ith ch e m ic a l p r o c e s sing and the o th e r w ith m ach in ing so lid s a m p le s .3 .3 . A t th e o th e r end of the L ink c o r r id o r , aw ay f ro m the bu ild ing co n ta in in g th e R e a c to r H a ll an d th e H ot L a b o r a to r ie s , C hang ing R o o m s le a d in to th e seco n d bu ild in g w hich c o m p le te s th e R e a c to r C e n tre . T h is bu ild ing h a s tw o w in g s , one w ing c o n ta in s th e a d m in is t r a t io n o f f ic e s , l e c tu r e th e a t r e , co n fe re n c e ro o m and l ib r a r y and is co m p le te ly f r e e a t a l l t im e s f ro m r a d i a tio n s o u r c e s . T h e o th e r w ing co n ta in s a v a r ie ty of la b o ra to r ie s opening off a c e n t r a l c o r r id o r . T h e s e la b o r a to r ie s in c lu d e an e le c t r i c a l w o rk sh o p , a m e c h a n ic a l w o rk sh o p , d a r k - ro o m s , c h e m ic a l an d b io lo g ic a l la b o ra to r ie s , a n im a l h o u se , lo w - le v e l coun ting ro o m , and g e n e ra l-p u rp o s e la b o ra to r ie s . A ll of th e s e ro o m s a r e equ ipped in a m a n n e r s im i la r to th o se found e l s e w h e re , f o r ex am p le in u n iv e r s i t ie s , and a r e in te n d ed f o r h an d lin g and e x p lo itin g ra d io a c tiv e m a te r ia l in th e ra n g e up to about 1 m e of gam m a r a d i a tio n .

4. TH E REA CTOR

4 .1 . T he r e a c to r s e le c te d fo r the C e n tre is th e 100-kW U niversity Teaching and R e se a rc h r e a c to r (UTR 100) des igned by A dvanced Technology L a b o ra to r ie s (ATL), a D iv ision of A m erican S tandard .4 .2 . F ig u re 2 show s a s im p lif ied sk e tch of the r e a c to r . The m o st o u ts tan d ing f e a tu re i s th e a r r a n g e m e n t of th e fu e l in tw o r e c ta n g u la r ta n k s th ro u g h w hich w a te r is fo rc e d a s coolan t, se p a ra te d by 45 cm of g rap h ite a s m o d e ra to r and su rro u n d e d by a t le a s t 30 cm of g ra p h ite a s r e f le c to r . Two th e rm a l co lum ns of g ra p h ite ex tend h o r iz o n ta lly f ro m opposite s id e s of the re f le c to r . T h e s m a l le r of th e s e ends in a la rg e pool of w a te r 1 . 5 m X 1 . 8 . m X 4 . 8 . m deep . T he l a r g e r th e rm a l colum n ex tends fo r 1 . 5 m and p ro v id es a b a re face1. 2 m X 1 .2 m beh ind a re m o v a b le c o n c re te sh ie ld in g d o o r. T h e sh ie ld in g a ro u n d th e r e a c to r i s e s s e n t ia l ly m o n o lith ic c o n c r e te w ith re m o v a b le to p c lo s u r e s .4 . 3. N u m ero u s th ro u g h -h o le s p ie rc e th e r e a c to r both h o rizo n ta lly and v e r t ic a l ly . Tw o of th e s e (10 c m X 10 cm ) p a s s h o r iz o n ta lly th ro u g h th e c e n tr e of th e c o re and a s im i la r ho le p a s s e s h o r iz o n ta lly a c r o s s th e la rg e th e rm a l co lu m n , 30 cm f ro m th e ju n c tio n w ith th e r e f le c to r . A l a r g e v e r t i c a l h o le (15 cm X 15 cm ) ru n s down f ro m th e top of th e r e a c to r to in te r s e c t one of th e h o r iz o n ta l th ro u g h -tu b e s in th e c e n tr e of th e c o r e . F o u r s m a l le r h o le s g rouped a ro u n d th is la rg e cen trad ho le a lso ru n down in to the c e n tra l reg io n of th e c o r e . A to ta l of 15 h o r iz o n ta l h o le s , e a c h 10 c m X 10 c m , ru n th e e n t i r e le n g th of th e th e rm a l co lu m n , th e c e n t r a l h o le co n tin u in g th ro u g h a


Fig. 2

The UTR 100 Reactor (SRRC)

le a d g a m m a s h ie ld 1 . 2 m X 1 . 2 m X 10 c m th ic k , on to w ith in 2. 5 c m of g ra p h ite aw ay f ro m a fu e l ta n k .4 . 4 . A ll of th e s e h o le s in th e r e a c to r a r e n o rm a lly f i l le d w ith re m o v a b le g ra p h ite p lugs in the c o re and w ide c o n c re te p lugs in the sh ie ld , a l l of which a r e re a d ily rem o v ed fo r a c c e s s .4 . 5. A n e n la rg e d d ra w in g of th e c o r e i s show n in F ig . 3, w h ich in c lu d e s d e ta ü s of th e fo u r id e n tic a l c o n tro l ro d s of B o ra l , w h ich a r e a c tu a lly fo u r f la t p la te s w hich ru n down lik e b lin d s on th e o u ts id e of th e fu e l ta n k s . One of th e s e c o n tro l ro d s is u s e d f o r a u to m a tic p o w er c o n tro l em p lo y in g f e e d b ac k f ro m a n e u tro n d e te c to r . T h e r a t e of flow of c o o la n t w a te r and th e w a te r t e m p e r a tu r e can bo th be v a r ie d in d e p en d e n tly of e a c h o th e r and th e r e a c to r p o w e r le v e l .4 . 6 . T he th e rm a l n eu tro n f lu x es in the g rap h ite a r e shown in F ig . 4, to g e th er w ith so m e v a lu e s f o r c a d m iu m r a t i o s . I t c a n b e s e e n th a t th e f lu x v a lu e s a r e v e r y h ig h ( 1 0 i2 n /c m 2 s) and u n ifo rm in th e c e n t r a l re g io n of th e c o re , an d ev en a t th e e x tre m e en d s of th e tw o th e r m a l co lu m n s th e n e u tro n f lu x v a lu e s a r e a ro u n d 1 0 a n /c m * s .4 . 7. A s u m m a ry of th e c h a r a c t e r i s t i c s of th e UTR 100 i s given in T ab le I .

5. RADIOISOTOPE PRODUCTION

5 .1 . A ll of th e h o le s w h ich p ie r c e th e r e a c to r ca n in f a c t be u s e d f o r th e p ro d u ctio n of rad io iso to p e s , bu t th e m o s t convenien t a rra n g e m e n t c o n s is ts of th e c a v it ie s in th e c o re w hich te rm in a te the ra b b it tu b e s . A s in g le tube w ith

118 A. WARD

Fig. 3

The core of the UTR 100 (SRRC)

an in te r n a l d ia m e te r of ab o u t 6 cm ru n s f ro m the c h e m ic a l p ro c e s s in g Hot L a b to a s in g le c a v ity r ig h t up a g a in s t th e end of a fu e l ta n k w h e re th e r e is a r e a s o n a b le h ig h e n e rg y n e u tro n com ponen t.

T he o th e r r a b b it - tu b e sy s te m h a s two send ing s ta tio n s , one in each Hot L ab , and th e tw o b ra n c h e s of th e r a b b it tu b e s co m e to g e th e r and th e n t e r m in a te in a cy lin d e r of g ra p h ite (22.5 cm d ia m .) w hich h as s ix c a v itie s . The g ra p h ite c y lin d e r l ie s in th e c e n tr a l reg io n of the c o re w ith i ts ax is h o r iz o n t a l an d e a c h c a v ity c a n be r o ta te d in tu r n in to th e re c e iv in g p o s it io n . T h e in s id e d ia m e te r of th e ra b b it tu b e s and s ix c a v itie s in th is sy s te m is a lm o s t4 cm .5. 2. T h e p r o c e d u re d u r in g i r r a d ia t io n s w ill b e to lo a d th e m a te r i a l to be i r r a d i a t e d in to a r a b b i t in one o r o th e r of th e H ot L a b s . T h e s e n d e r th e n r e q u e s ts by te lep h o n e the r e a c to r o p e ra to r a t th e c o n tro l co n su le , w hich is m oun ted in a ro o m w hich p ro je c ts o v e r the R e a c to r H all, to send the loaded r a b b i t in to one of th e c a v i t ie s in th e c o r e . T h e o p e r a to r h a s an a u to m a tic t i m e r on th e c o n s u le an d w ill p re v io u s ly h av e s e t th e r e a c to r c o n t ro ls so th a t any re a c tiv ity effec t of the sam ple w ill not throw the re a c to r out of au to m a tic c o n tro l . A t th e end of th e s e le c te d i r r a d ia t io n p e r io d th e e le c tro n ic t im e r on th e co n su le w ill au to m a tic a lly e je c t the ra b b it out of the c o re back along th e ra b b it tu b e s to the Hot L ab it o r ig in a lly cam e fro m , o r to the o th e r Hot L ab . T he n eu tro n flux du rin g ir ra d ia tio n is c h a r t- re c o rd e d au tom atica lly on th e c o n tro l consu le and the au tom atic co n tro l ho lds the flux constan t, p e r m ittin g v a lu es of induced ac tiv ity to be ca lcu la ted and rep e a te d w ith accu racy .5. 3. O n a r r i v a l in th e H ot L ab th e r a b b i t tu b e te rm in a te s in a le a d - l in e d

TABLE I


C H A R A C T E R IST IC S O F U T R -100

M axim um continuous power leve l 100 kW

C ritic a l mass ~ 3. 0 kg U235

G eom etry Two 6 i n x 20 in slabs separated by 18 in o f g raph ite and re flec tedby 12 in o f graphite

M oderator-coolant Light w ater

Excess keff 1.5% Д к Д

Prom pt-neutron life tim e 1 . 3 5 х ю Л

Fuel e lem entsNumber of fu e l-e le m e n t ássem blies 12

Number o f fuel p lates per assem bly 12

F u e l-p la te dimensions 26 in X 3 in X 0. 080 in■Enrichment 90% (appr. ) U 235

U 235 per p la te 23 gWater gap 0 .4 0 inC ladding 20 rails o f a lum in iumF ue l-con ta in ing m atrix U 0 2 + A1

ReflectorM aterial G raphiteDimensions 4 4 in X 56 in X 48 in

C ontrol rodsN umber 4Worth

One rod ~ 1. 0% A k /kFour rods ~ 4 . 8% Д к A

SpeedW ithdrawal ra te ~ 3 in /m inScram (tim e for com ple te insertion) ~ 0 . 5 s

C ontro l e lem entsM aterial BoralS ize 9 in x 23 in X 1 /8 in

R eactiv ity input ratesOne rod ~ è 0 .0022% Д к Д s (av. )Four rods ~ ± 0. 01% Д к Д s (av . )

R eactiv ity effects1°}o change in fuel loading ~ ± 0.3% Д к ДN egative tem pera tu re coeffic ien t 0.007% Д к Д per “СN egative void (m oderator) coeffic ien t 0 . 1 7 % -Д к Д per % voidRem oval of w ater from core tank -ЗО^о Д к Д (ap p r.)

Process waterPurity 0.5 ppm to ta l solids,

1 m icrom ho conductiv ityFlow

S tart-up 10 gpmOperating 4 -7 5 gpm (adjustable)T em perature 75e F m in , 180°F m ax (adjustable)

120 A. WARD

THERMAL COLUMN

NOTES: x - Point where indicated value of cadm ium ratio was measured. Cadm ium ratio measured with 0. 002-in gold foils. Contour lines are isoflux lines. Values indicated are therm al-flux levels (n /c m 2 s) a t a reactor power level of 100 kW.

VERTICAL CENTREPLANE

Fig-4.

Approximate neutron flux distributions in the UTR 100

e n c lo s u re w hich i s f i t te d w ith sw iv e llin g re m o te tongs f o r h and ling and w ill p ro b a b ly be su rv e y e d by a te le v is io n c a m e ra w hose fo cu s and d ire c tio n a r e e le c tro n ic a lly c o n tro lle d f ro m o u tsid e th e e n c lo su re . T he sy s te m is flex ib le a s th e le a d w a lls of th e e n c lo s u re a r e m ade of in te r le a f in g b r ic k s , and th e c lo se d c ircu it, te le v is io n c a m e ra and c o n tro ls a r e sm a ll, lig h t and p o r ta b le . F u m e cu p b o a rd fa c i l i t ie s and v e ry la rg e v en tila ted glove boxes a r e ava ilab le in th e Hot L ab s , w hich can be com bined w h ere n e c e s s a ry w ith the le ad -lin e d e n c lo su re and te le v is io n c a m e ra .

5 .4 . T he f in a l p ro d u c t of th e se Hot L abs should be a p ro c e s se d , ch em ica lly and p h y s ic a lly , ra d io a c tiv e sa m p le loaded in to a p o r ta b le sh ie ld ed co n ta in e r f o r t r a n s p o r t e i th e r o u ts id e th e C e n tre o r th ro u g h th e L ink in to th e la b o r a to r i e s beyond .

5 . 5 . In th e s e la b o r a to r ie s , a s I h av e m e n tio n e d p re v io u s ly , th e f a c i l i t i e s e x is t fo r a w ide v a r ie ty of e x p e r im e n ts involv ing s h o r t- l iv e d ra d io iso to p e s .


P R O JE C T S

Q u ite g e n e ra lly , th e p e c u l ia r v a lu e of s h o r t- l iv e d ra d io iso to p e s i s th a t th ey can be p ro d u ce d w ith re la t iv e ly h igh a c t iv i t ie s in s h o r t t im e s and a f te r th e i r e x p lo ita tio n in p a r t i c u la r a p p lic a tio n s th e i r a c tiv i ty d ie s aw ay ra p id ly and th ey soon p re s e n t no p ro b le m of con tinued ra d ia tio n dam ag e o r d isp o sa l of ra d io a c tiv e w a s te .

T h e s e a r e u s u a l ly th e c h a r a c t e r i s t i c s th a t a r e r e q u i r e d in r e s e a r c h p r o b le m s of q u ite d i f f e r e n t ty p e s e x te n d in g o v e r v a r i e d f i e ld s .

P r o je c ts invo lv ing s h o r t- l iv e d ra d io iso to p e s w hich have b een su g g ested inc lude:(1) S tu d ies of effluen t d isp o s a l in e s tu a r ie s , u s in g m o d e ls .(2) M e a su re m e n ts of w e a r in d if fe re n t m a te r ia ls .(3) A c tiv a tio n a n a ly s is w ith p a r t i c u la r r e f e r e n c e to a p o s s ib le c o r r e la t io n

b e tw e en t r a c e e le m e n ts an d s to m a c h c a n c e r .(4) T r a c e r e x p e r im e n ts in p la n ts and a n im a ls .(5) M ed ica l ap p lica tio n s fo r m etab o lic m e a su re m e n ts , d iag n o sis and therapy .

T h e se p ro je c ts have been s e le c te d to i l lu s t r a te the w ide v a r ie ty of p ro b lem s'.

I h av e a l re a d y d raw n y o u r a t te n tio n to th e fa c t th a t in th e re g io n of th e ra d io iso to p e p ro d u c tio n f a c ility , th e flux d is tr ib u t io n s a r e v e ry u n ifo rm and th is , coupled w ith au to m atic c o n tro l of the r e a c to r du ring ir ra d ia t io n s , w hich a r e p r e c i s e ly t im e d , w il l g r e a t ly f a c i l i t a t e th e p ro d u c tio n of a c c u r a t e ly - know n a m o u n ts of a c t iv i ty in r e p e a te d i r r a d i a t i o n s .

T h e s e a r e th e ty p e s o f f a c to r s w h ich in p r a c t ic ë w ill b e im p o r ta n t in th e e x p lo ita tio n of s h o r t - l iv e d r a d io is o to p e s in th is r e a c to r .

I w o u ld l ik e to d ra w y o u r a t te n t io n to a n e a r l i e r p a p e r p r e s e n te d byS . C . CU R RA N [1] a t th e S e v en th M e e tin g of th e B r i t i s h N u c le a r E n e r g y S o c ie ty on 27 S e p te m b e r , 1962, w hich d e s c r ib e s th e S c o ttish R e s e a rc h R e a c to r C e n tre f ro m th e p o in t of view of education in n u c le a r en e rg y . T ec h n ic a l d e ta i l s o f th e r e a c to r in th is e a r l i e r p a p e r d if fe r s lig h tly f ro m th o s e g iven h e re b ec au se th e g roup co n c ern ed have taken the opportun ity of accep ting con tinued im p ro v e m en ts in des ig n by A T L.

T h e te c h n ic a l d e ta i ls g iv en in th e p r e s e n t p a p e r s u p e rs e d e any given p re v io u s ly and a r e a lm o s t c e r ta in ly f in a l .


I w ou ld l ik e to ta k e th is o p p o rtu n ity of e x p r e s s in g th e a p p r e c ia t io n of the g roup f ro m a l l the U n iv e rs it ie s co n c ern ed w ith the R e a c to r C e n tre u n d er th e c h a irm a n s h ip of D r .S .C .C u r r a n , f o r th e p a t ie n c e , u n d e rs ta n d in g an d sk il le d te c h n ic a l c o -o p e ra tio n re c e iv e d fro m A dvanced T echnology L a b o ra to r ie s who d e s ig n e d th e r e a c to r and th e M in is try of W o rk s in London who d e s ig n e d th e R e a c to r C e n tre .

R E F E R E N C E

[1] CORRAN, S .C ., "A University Reactor C entre", J. Brit. Nucl. Energy Soc. . 1 (1962) 178.

122 A. WARD

D I S C U S S I O N

P . BUSSIERE: You say th a t you a r e ab le to hold the flux of y o u r r e a c to r c o n s ta n t, so th a t you can r e p e a t a c tiv a tio n s a c c u ra te ly . I w ould lik e to a s k w h a t a c c u ra c y you o b ta in and d u r in g w hat p e r io d of t im e ?

A . WARD: You u n d e rs ta n d of c o u r s e th a t th is r e a c to r i s b e in g c o n s t r u c t e d . If I r e c a l l c o r r e c t ly , th e e x p e c te d v a r ia t io n s in th e p o w e r le v e l a r e a b o u t 1 o r 2%.

W . W . M EIN K E: O u r e x p e r ie n c e a t M ich ig an h a s b e e n th a t th e a c tu a l n e u tro n flux a t a p a r t i c u la r s a m p le can v a ry a s m uch a s ± 5% o v e r p e r io d s of w eek s w h ile th e p o w er le v e l r e m a in s a t a " c o n s ta n t" v a lu e . Som e of th is v a r ia t io n can be ex p la in e d by o c c a s io n a l ch a n g e s in th e c o r e co n fig u ra tio n . H o w ev er, even w ith in th e sa m e day and w ith in th e s a m e h o u r w e have found v a r ia t io n s of a s m u ch a s s e v e ra l p e rc e n t f o r " c o n s ta n t" p o w er le v e ls .

A . W ARD: T h e s e r e s u l t s w h ich you h a v e q u o te d a r e v e r y in te r e s t in g , th o u g h v a r ia t io n s of th is o r d e r w ould n o t in f a c t w o r ry u s .

C . TA Y LO R: (C h a irm a n ): D r . M einke, a r e you b o th e re d by a v a r ia t io n of 5% ?

W . W . M EIN K E: N o. W e w ould m o n ito r e a c h t im e of c o u r s e . T h e a u th o r s o f s o m e of th e p a p e r s p r e s e n te d h e r e m a in ta in th a t th e y w e r e a b le to k e e p th e f lu x c o n s ta n t to w ith in 1%, b u t I f in d th i s r a t h e r s u r p r i s in g .

C . T A Y L O R : I t i s im p o r ta n t n o t to p r e s s th i s d e m a n d f o r c o n s ta n c y to o f a r , i s n ’t i t? T h e e x p e n se b e c o m e s t e r r i f i c .

W . W . M EIN K E: T h a t i s c o r r e c t , and o u r r e a c to r i s c e r ta in ly s a t i s f a c to r y f o r u s a s lo n g a s w e m o n ito r e a c h t im e .

EXPERIENCES WITH THE IRRADIATION OF AMMONIUM BROMIDE

K. HEYDORNISOTOPE DIVISION, RESEARCH ESTABLISHMENT RIS0,

ROSKILDE, DENMARK


EXPERIENCES WITH THE IRRADIATION OF AMMONIUM BROMIDE. Irradiation of am m onium bromide with slow neutrons is a routine method for d ie production of Br82 for many purposes.

While the m ajority of our irradiations a re carried out in a therm al colum n, i t was found desirable in some cases to increase the specific activ ity by irrad iating in positions close to the reactor core.

During one such irrad iation , rupture o f the irradiation can occurred, resulting in severe contam ination of the irrad iation tube and also of the air in the reactor h a ll. Rupture of the irrad iation cans requires 8 -10 atm ospheres gas pressure, corresponding to a high degree of decom position of the ta rg e t m a te ria l.

An investigation o f am m onium brom ide irradiations showed that evolution of Nz > H2 , HBr and Br2 had taken p lac e , and two series of experim ental irradiations were carried out in order to obtain quan tita tive in form ation on the amounts o f gases evolved.

Electron irradiations, carried out using a linear acce le ra to r, gave a G(H2) value of 0 .51 ; this figure is considered v a lid also for reacto r gam m a rad ia tion , and approx im ate ly so for therm al neutrons. Reactor irradiations in d ica ted l i t t le in fluence from fast neutrons.

Hydrogen formation up to 200 cm3 /g was observed, corresponding to a radiation decomposition of appro»* m ately 47%.

EXPERIENCES D'IRRADIATION DE BROMURE D'AMMONIUM. L 'irradiation du bromure d 'am m onium par des neutrons lents est une m éthode courante qui p e rm et d 'o b ten ir du b rom ure-82 à des fins diverses.

Alors que la plupart de ces irradiations s'effectue dans la colonne therm ique, i l a é té jugé souhaitable dans certains cas, pour accro ître l 'a c tiv ité spécifique, de pratiquer l'irrad ia tio n près du cœ ur de réacteu r.

Au cours d 'une de ces irradiations, la gaine contenant la m atière à irradier s 'est rom pue, ce qui a eu pour e ffe t une con tam ination grave du can a l d 'irrad ia tio n e t aussi de l 'a i r dans la sa lle du réacteu r. Pour qu*il y a it rupture, i l faut que la pression des gaz soit de 8 à 10 a tm , ce qui correspond à un taux de décomposition é lévé de la m atière étudiée.

Il ressort d 'u n e étude d 'irrad ia tions du brom ure d 'am m onium q u 'i l y a eu évolution de N z» H2 , HBr e t Br2 ; on a procédé à deux séries d 'irradiations expérim entales en vue de recueillir des données quantitatives sur les gaz dégagés.

Des irradiations par des é lectrons, faites à l 'a id e d 'un accé léra teu r lin éa ire , ont donné une valeur de G (H s) ég a le à 0 ,51 ; on estim e que ce chiffre est ég alem en t va lab le dans le cas d 'une Irrad iation par des rayons gam m a produits dans le réacteur e t qu 'il s'applique aussi approximativement dans le cas d'une irradiation par des neutrons therm iques. I l ressort des irradiations e ffectuées dans le réacteu r que le rô le des neutrons rapides e st m in im e.

On a observé la formation d'hydrogène jusqu'à concurrence de 200 cm3 /g , correspondant à une décomposition sous l'e ffe t des rayonnements (environ 47%).

ОПЫТЫ С ОБЛУЧЕНИЕМ БРОМИДА АММОНИЯ. Облучение бромида аммония медленными нейтронами является обычным способом получения Вг82, используемого для многих целей.

Так как в большинстве случаев такое облучение осуществлялось в нашей тепловой колонне, бмяо решено в ряде случаев увеличить удельную активность путем облучения в участках, расположенных близко к активной зоне реактора.

Во время одного такого периода облучения произошел разрыв оболочки, приведший к серьезному загрязнению облучаемого контейнера, а также воздуха в зале реактора. Для разрыва оболочки требуется величина давления газа в 8 - 10 атмосфер, соответствующая высокой степени разрушения материала мишени.

123

124 К. HEYDORN

Исследование облучений бромида аммония показало, что имело место выделение Н2 , Н 2> НВг и Вг2 . Было проведено две серии экспериментальных облучений для того, чтобы получить достаточную информацию о количестве выделяемых газов.

Электронные облучения, проводившиеся с использованием линейного ускорителя, дали значение G(H2)« равное 0,51¡ эта цифра считается действительной также для гамма-излучения, образующегося в реакторе, и будет приблизительно такой же для тепловых нейтронов. Облучения в реакторе показали незначительное воздействие со стороны быстрых нейтронов.

Наблюдалось образование водорода в пределах до 200 смэ/г, что соответствует разложению под действием излучения приблизительно на 47$.

EXPERIENCIAS SOBRE LA IRRADIACION DE BROMURO DE AMONIO. La irrad iación del brom uro de am onio con neutrones lentos constituye un m étodo corrien te de ob tención de 82 Br para m uchos fines.

Aunque la m ayoría de esas irradiaciones se efectúan en la colum na té rm ica , los autores consideraron conveniente increm entar en algunos casos la actividad específica irradiando en posiciones próximas a l cuerpo del reactor.

Durante una de estas irradiaciones, reventó e l rec ip ien te de irrad iac ión , provocando una grave contam inación del canal de irradiación y tam bién de la atmósfera en la sala del reactor. La ruptura de los re c ipientes de irrad iac ión requ iere una presión gaseosa de 8 a 10 a tm ósferas, lo que corresponde a un elevado grado de descom posición del m a te ria l de l b lanco.

El estudio de las irradiaciones del bromuro de am onio reveló que se habían desprendido N2 » Нг , НВг y Br2 ;se llevaron a cabo dos series de irradiaciones experim entales a fin de obtener datos cuantitativos sobre e l volum en de gases desprendidos.

Las irradiaciones e lectrón icas , efectuadas con un acelerador l in e a l, dieron un valor G ( l^ ) de 0 ,51 ; •se estim a que esta cifra es válida también para los rayos gamma producidos en reactores y, de un modo aproximado, para los neutrones térmicos.

Se observó e l desprendim iento de hasta 200 cm3 de hidrógeno por gram o de NH4Br, lo que corresponde a una radiodescomposición del orden de 47 por ciento.

INTR OD U CTIO N

In th e l a s t few y e a r s ra d io a c t iv e b ro m in e h a s found in c re a s in g u s e in D en m a rk a s a t r a c e r in m e d ic a l r e s e a r c h a s w ell a s fo r in d u s tr ia l ap p lic a tio n .

T h e u s e of b r o m in e - 82 in l a r g e - s c a l e in v e s t ig a t io n s of flow p a t te r n s f ro m d iffe re n t lo c a tio n s of sew age o u tle ts in to th e se a re q u ire s co n s id erab le am o u n ts of a c tiv i ty , and th is a p p lic a tio n h a s g iv en r i s e to a p ro d u c tio n of 4 -5 с of b ro m in e -8 2 p e r w eek .

P ro d u c tio n of b r o m in e - 82

B ro m in e -8 2 i s in v a r ia b ly p ro d u ce d by n e u tro n ir ra d ia t io n of b ro m in e - co n ta in in g com pounds, fo llow ed by a cooling p erio d of about one day to allow f o r d ec ay of b r o m in e - 80.

A s p e c if ic a c tiv i ty of 7 m c / g of b ro m in e p e r h o u r of i r r a d ia t io n a t af lu x of 1 0 12 n /c m ^ s i s d i r e c t ly o b ta in ed , b u t by s u ita b le ch o ic e of t a r g e tm a te r ia l th e S z ila rd -C h a lm e rs r e a c tio n can be u til iz e d to in c re a s e th e s p e c ific a c tiv i ty by one o r tw o o r d e r s of m agn itude.

T h e y ie ld f ro m th e s e r e a c t io n s , h o w ev er, is o ften a s low a s 50%, andfo r m any in d u s t r ia l ap p lica tio n s a su ffic ien t sp e c if ic ac tiv ity can be ob ta ined by a s im p le ac tiv a tio n of in o rg an ic b ro m id e s .

A m m o n iu m b ro m id e , p o ta s s iu m b ro m id e , and b a r iu m b r o m id e h av e b e e n u se d fo r su ch i r r a d ia t io n s , bu t am m onium b ro m id e i s o ften p r e f e r r e d ,

EXPERIENCES WITH THE IRRADIATION OF AMMONIUM BROMIDE 125

b e c a u s e th e a m m o n iu m -io n d o e s n o t g iv e r i s e to c o n ta m in a tin g a c t iv i t ie s b y n e u tro n c a p tu r e .

I r r a d i a t io n s in D (a n ish ) R (e a c to r) 2

T h e m a jo r i ty of am m o n iu m b ro m id e i r r a d ia t io n s fo r th e p ro d u c tio n of b r o m in e -8 2 i s c a r r i e d o u t in a p n e u m a tic - tu b e s y s te m e x te n d in g in to th e th e r m a l co lu m n of DR2 [1 ].

A m ax im u m of 16 g of am m onium b ro m id e ANALAR g ra d e is i r r a d ia te d to a sp e c if ic ac tiv ity of 90 m c /g b ro m in e a t p ile -o u t in a h e a t- s e a le d , doub lew a ll b ag m a d e f ro m -0. 1 m m polyv iny l a lco h o l s h e e t. T h is w ra p p in g m a k e s th e i r r a d ia te d m a te r i a l e a s y to h an d le , and th e p o ly v in y l a lc o h o l en v e lo p e i s r e a d i ly d is s o lv e d in w a te r to g e th e r w ith th e am m o n iu m b r o m id e a t th e t im e of a p p lic a tio n .

In so m e c a s e s i t h a s b een n e c e s s a ry to p ro d u ce Br82 in h ig h e r sp e c if ic a c t iv i t ie s , and a n u m b e r of i r r a d ia t io n s h av e b ee n c a r r i e d out in p o s it io n s c lo s e to th e r e a c t o r c o r e . A m m o n iu m b ro m id e i s i r r a d i a t e d d i r e c t ly in s ta n d a r d a lu m in iu m c a n s su sp e n d e d in th e w a te r - f i l l e d i r r a d ia t io n tu b e s , and th e c a n s a r e le a k - te s te d by th e e th y len e g ly c o l m ethod b e fo re in s e r t io n .

In one c a s e a m in o r le a k d ev e lo p ed d u r in g i r r a d ia t io n , and in a n o th e r th e can lid b lew off w hen b e in g opened by th e c u s to m e r . F in a lly an i r r a d ia t io n c a n r u p tu re d d u r in g i r r a d ia t io n , c a u s in g s e v e r e c o n ta m in a tio n of th e i r r a d ia t io n tu b e and a ls o of th e a i r in th e r e a c to r h a ll .

An in v e s tig a tio n of a v a ila b le i r r a d i a t e d am m o n iu m b ro m id e s a m p le s w as , th e re fo r e , in it ia te d in c lo se c o -o p e ra tio n w ith th e an a ly tic a l and o th e r g ro u p s of th e C h e m is t ry D e p a rtm e n t a t th e R is0 R e s e a r c h E s ta b lis h m e n t.

P r e l im in a r y in v e s tig a tio n s of i r r a d ia te d am m o n iu m b ro m id e

W here p o s s ib le , a n a ly s is w as c a r r i e d out on th e g a s in th e i r r a d ia t io n c a n s a s w e ll a s on th e so lid am m o n iu m b ro m id e , u t i l iz in g m a s s s p e c t r o m e t r y in c o m b in a tio n w ith c o n v e n tio n a l a n a ly t ic a l te c h n iq u e s

T h e a n a ly tic a l r e s u l t s , to g e th e r w ith o th e r o b s e rv a t io n s of th e g r o s s e f fe c ts o f th e i r r a d ia t io n , gave a q u a lita tiv e p ic tu re of th e ra d ia tio n d ec o m p o s it io n of am m o n iu m b ro m id e and th e d is t r ib u t io n of d ec o m p o s itio n p ro d u c ts .

I t w a s found th a t i r r a d i a t i o n g a v e r i s e to th e f o rm a tio n o f h y d ro g e n , n itro g e n , h y d ro g en b ro m id e , and f r e e b ro m in e , c o rre sp o n d in g to a n e t d e c o m p o s it io n r e a c t io n e q u iv a le n t to a c o m b in a tio n of th e tw o r e a c t io n s

2 NH4 B r -» N 2 + 4 H 2 + B r 2 - 5. 61 eV ,2N H 4B r -> N 2 + 3H 2 + 2 H B r - 4 . 90 e V .

T h e p r im a r y g a s e v o lv ed d u r in g i r r a d ia t io n c o n ta in s on ly p a r t o f th e d e c o m p o s i tio n p r o d u c ts . A fte r c o m p le tio n o f i r r a d ia t io n , s e c o n d a ry g a s i s s lo w ly l ib e r a te d f ro m th e am m o n iu m b ro m id e c r y s ta l s , and f in a lly p a r t o f th e g a s r e m a in s a s i n t e r s t i t i a l g a s in th e c r y s t a l s f o r e v e n m o r e th a n on e y e a r a f te r i r r a d ia t io n . T h e in te r s t i t i a l g a s i s l ib e r a te d by d is s o lu tio n o f th e c r y s ta l s o r by su b lim a tio n .

126 К. HEYDORN

A lth o u g h n o n e of th e g a s e s r e a c t c h e m ic a l ly w ith th e a lu m in iu m ca n w hen d ry , so m e c o r r o s io n w as o b s e rv e d in m o s t c a s e s . T h e a t ta c k w as c h ie f ly found in th e b o tto m of th e can and a p p e a re d p a r t l y a s p itt in g ; th is c o r ro s io n cou ld be a ttr ib u te d to the p re s e n c e of v e ry sm a ll am ounts of w a te r .

T h e te n d e n c y of th e g a s e s to e s c a p e f ro m th e c r y s t a l s s e e m e d to i n c r e a s e in the su c ce ss io n : N2 , H 2, H B r, and B r2 ; th e in te r s t i t i a l g as , th e r e f o re , te n d s to b e c o m e e n r ic h e d in n itro g e n in c o n t r a s t to th e p r im a r y and s e c o n d a ry g a s e s .

T h e to ta l d e g r e e of d e c o m p o s i tio n a t ta in e d in an i r r a d ia t io n o f 100 h w a s e s t im a te d a t ab o u t 2 0 %.

R a d ia tio n d e c o m p o s i t io n o f am m o n iu m b ro m id e

In o r d e r to p ro v id e q u a n t i ta t iv e in fo rm a tio n on th e d e c o m p o s i t io n of a m m o n iu m b r o m id e d u r in g r e a c t o r i r r a d i a t i o n u n d e r v a ry in g c o n d itio n s , tw o s e r i e s of i r r a d i a t i o n s w e re p e r f o rm e d .

One s e r i e s w as c a r r ie d out u s in g th e l in e a r e le c tro n a c c e le ra to r a t the R is0 R e s e a r c h E s ta b lis h m e n t, em p lo y in g d o s e - r a t e s o f th e s a m e o r d e r of m ag n itu d e a s th o se e n c o u n te re d d u rin g r e a c to r ir ra d ia t io n . W hen th e e le c tro n e n e rg y i s k ep t below th e b ind ing en erg y p e r nucleon in th e ta rg e t a tom s, a l l e n e rg y t r a n s f e r ta k e s p la c e v ia e le c tro n in te ra c t io n , and th e ra d ia t io n e f fe c t m a y be c o n s id e re d e q u iv a le n t to th e e ffe c t o f r e a c to r r a d ia t io n l e s s n u c le a r r e c o i l f ro m in te ra c t io n w ith n e u tro n s .

T h e se c o n d s e r i e s w a s c a r r i e d ou t in DR2, u s in g th e s a m e f a c i l i t i e s a s p re v io u s ly d e s c r ib e d . S ev era l com binations of th e rm a l flux, fa s t neu tron f lu x and 7 - ra d ia t io n w e re u se d fo r th e i r r a d ia t io n s , in o r d e r to get an in d ic a tio n o f th e s e p a r a te c o n tr ib u t io n s to th e to ta l r a d ia t io n d e c o m p o s i t io n .

A ll i r r a d i a t i o n s w e r e c a r r i e d o u t w ith B . D. H. A N A LA R a m m o n iu m b ro m id e , d r ie d in vacu o o v e r p h o sp h o ru s pen tox ide. I r r a d ia t io n t im e s fro m a few h o u rs to a few d ay s w e re u se d in bo th s e r ie s .

IR R A D IA TIO N S USING T H E L IN E A R A C C E L E R A T O R

S am p le s of am m o n iu m b ro m id e ra n g in g f ro m 0 . 2 - 1 . 0 g w e re w eighed in to a lu m in iu m c a n s w ith a v o lu m e of abou t 1 2 cm? and a w a ll th ic k n e s s of1 m m , c lo sed w ith E d w ard s 1/4 in d iap h rag m v a lv es , u sing K e l-F d iaph ragm s and s i l ic o n e r u b b e r О - r in g s . A fte r e v a c u a tio n , th e c a n s w e re f i l le d w ith h e liu m a t an a c c u ra te ly -k n o w n p r e s s u r e of abou t 400 m m of m e rc u ry .

T h e u s e of a know n a m o u n t o f h e l iu m , b e lo w a tm o s p h e r ic p r e s s u r e , p e r m i ts an a c c u ra te d e te rm in a tio n of th e q u a n titie s of g a s e s evo lved d u rin g i r r a d ia t io n , e v e n i f th e i r r a d i a t i o n c a n i s n o t a b s o lu te ly le a k - t ig h t . T h e n i t ro g e n and h y d ro g e n a r e m e a s u r e d r e la t iv e to h e l iu m , and th e s e r a t i o s a r e r e la t iv e ly in s e n s i t iv e to le a k a g e . L ea k ag e b e fo re i r r a d ia t io n w ill only in tro d u c e a tm o s p h e r ic a i r in to th e c a n , and le a k a g e a f te r i r r a d i a t i o n w ill n o t change th e r a t i o s b e tw een th e g a s e s , u n le s s th e le ak a g e is . so s m a ll th a t th e d if fe r e n c e in d if fu s io n r a t e i s im p o r ta n t , an d in th i s c a s e th e o v e r a l l lo s s i s in s ig n if ic a n t . O nly le a k a g e d u r in g i r r a d ia t io n w ill in f lu e n c e th e s e r a t i o s , te n d in g to g iv e an o v e r - e s t im a te of ev o lv ed g a s .


T h e i r r a d ia t io n c a n s w e re m o u n ted in a w a te r -c o o le d a s s e m b ly f i t te d to th e c o n v e y o r b e l t b e lo w th e e le c t r o n - b e a m w indow o f th e a c c e l e r a to r . T he co nveyo r b e lt w as s e t to m ove to and f ro a t r ig h t an g les to th e scann ing e le c tro n b ea m , so a s to e n s u re s im u lta n e o u s and u n ifo rm i r r a d ia t io n of a ll sa m p le s . T he v a lv e s w ere p ro te c te d ag a in s t ra d ia tio n f ro m se co n d a ry e le c tro n s by sh ie ld in g w ith 5 m m of le ad sh e e t.

I r ra d ia tio n took p la ce w ith 7. 5 MeV e le c tro n s a t a d o s e - ra te of 5. 5 M rad p e r p a s s a g e , c o r re s p o n d in g to a m e a n d o s e - r a t e o f ab o u t 1. 5X 10й r a d /h . T h e te m p e r a tu re of th e coo ling w a te r d u rin g i r ra d ia t io n d id not exceed 22°C.

A n a ly s is of th e i r r a d ia te d sa m p le s

W hen i r r a d ia t io n w as co m p le te th e i r r a d ia t io n can w as connected to the g as sa m p lin g sy s te m a t A in F ig . 1, u sin g vacuum jo in ts w ith s ilico n e ru b b e r О - r in g s . T h e s y s te m w a s e v a c u a te d a t B , w ith s to p - c o c k 3 c lo s e d , to a

TO VACUUMв

Gas sampling system

p r e s s u r e of abou t 2 0 m m of m e r c u r y , and only a f te r c lo s in g s to p -c o c k s 2

and 5 w e re th e tw o p a r t s o f th e s y s te m a llow ed to c o m m u n ic a te by opening s to p -c o c k 3.

A fte r p r e s s u r e eq u ilib ra tio n , n ee d le -v a lv e 1 is c lo sed and th e d iap h rag m v a lv e in th e i r r a d ia t io n c a n i s opened . T he p r im a r y g a s in th e can i s now p a s se d slow ly in to th e sy s te m th ro u g h n e e d le -v a lv e 1, th e H B r and Вгг being a b s o rb e d in 0 .1 N NaOH in th e w a sh -b o ttle , th e N2 , H2 , and He p a s s in g on to th e g a s -p ip e tte .

W hen e q u ilib r iu m is o b ta in ed th e p r e s s u r e i s r e c o rd e d and th e i r r a d i a t io n can v a lv e c lo se d . A fte r c lo s in g s to p -c o c k s 3 and 4 th e s y s te m can be d is a s s e m b le d and a n a ly s is o f th e p r im a r y g as can be c a r r i e d ou t.

An a liq u o t o f th e so lu t io n in th e w a s h - b o tt le w a s a n a ly s e d f o r B r2 by th e a d d itio n of N a l and t i t r a t io n w ith N /1 0 0 И агЗгО з so lu tio n . T h e r e s t of th e sa m p le w as t r e a te d w ith SO2 to r e d u c e Вгг to B r “, and to ta l B r w as d e te r m in e d tu r b id im e t r i c a l ly b y th e a d d itio n o f AgN 0 3 a f t e r a c id ify in g a n d r e m o v a l o f e x c e s s SO2 .

128 K. HEYDORN

T h e g a s in th e g a s - p ip e t te w a s a n a ly s e d f o r H e, H 2, N2 , 0 2, and A r b y m a s s s p e c t r o m e te r . T h e r e c o v e r y of h e l iu m w a s , in m o s t c a s e s , in e x c e s s of 90%, even when th e p r e s s u r e in th e i r ra d ia tio n can exceeded 2 atm and a n a ly s is w as m ade m o re th a n 3 d a f te r ir ra d ia t io n . T he evolved q u an tit ie s of h yd rogen a r e d e te rm in e d d ire c tly by the H 2: He r a t io s in the sam p les , b u t th e am oun ts of n itro g e n a r e d e te rm in e d only a f te r c o r re c tio n fo r a tm o sp h e r ic a i r in th e sa m p le . T h e n itro g e n evo lu tion is , th e re fo r e , l e s s a c c u r a te ly d e te rm in e d th a n th e h y d ro g en evo lu tion .

T h e c lo se d i r r a d ia t io n can s t i l l co n ta in s a known am ount of h e liu m and, a f te r 1 - 2 d, s e c o n d a ry g a s i s d e te rm in e d r e la t iv e to h e liu m by m a s s - s p e c tro m e try on a sa m p le d raw n d ire c tly f ro m th e can . Only H2 and N2 can b e d e te rm in e d , s in c e th e m a s s s p e c tr o m e te r is u nab le to m e a s u re H B r and B r2 .

A ll r e s u l t s f ro m th e a n a ly s i s o f p r im a r y an d s e c o n d a ry g a s a r e e x p r e s s e d in m il l ig ra m s o r cubic c e n tim e te rs p e r g ra m of o r ig in a l am m onium .b ro m id e in th e ir ra d ia t io n can .

F in a lly th e can w as opened and th e so lid am m o n iu m b ro m id e w as a n a ly s e d s e p a r a te ly fo r B r 2, H B r, and in te r s t i t i a l g as .

A w eighed sa m p le of am m o n iu m b ro m id e w as r a p id ly t r a n s f e r r e d to a 10% N al so lu tipn ; B r 2 w as d e te rm in e d by t i t r a t io n w ith N /100 N a2 S 20 3 s o lu tion .

A n o th e r s a m p le w a s d is s o lv e d in w a te r , and B r 2 w a s re m o v e d b y r e p e a te d e x t r a c t io n s w ith c h lo ro fo rm . H B r w a s d e te r m in e d in th e a q u e o u s so lu tio n by t i t r a t io n w ith N / Í 0 0 NaOH, u s in g m e th y l o ra n g e a s an in d ic a to r .

T h e r e s t of th e am m o n iu m b ro m id e w as w eig h ed in to a p ip e tte , w h ich w as f il le d w ith an a c c u ra te ly -k n o w n am ount of h e liu m a t a p r e s s u r e of about 250 m m of m e rc u ry . T h e sa m p le w as h e a te d to co m p le te su b lim a tio n , and a f te r coo ling th e to ta l am ount of in te r s t i t i a l gas w as d e te rm in e d by p r e s s u r e m e a s u r e m e n t , u s in g C 0 2 a s a b u f fe r b e tw e en th e p ip e tte and th e m e r c u r y m a n o m e te r .

A fte r p r e s s u r e m e a su re m e n t, th e in te r s t i t i a l gas w as ana ly sed by m a ss s p e c t r o m e te r to d e te rm in e th e ev o lv ed q u a n ti t ie s of H2 and N2 r e la t iv e to h e liu m . A s a m p le of u n ir r a d ia te d am m o n iu m b ro m id e gave a b la n k v a lu e of 0. 004 cm 3 H2 /g .

A ll r e s u l t s f ro m th e a n a ly s is of th e so lid am m onium b ro m id e had to b e e x p re s s e d in m il l ig r a m s o r cub ic c e n tim e te rs p e r g ra m of i r r a d ia te d s a m p le . O nly a f te r co m p le te a n a ly s is can th e r e s u l t s b e co n v e r te d to u n its p e r g ra m of o r ig in a l am m onium b ro m id e in th e i r r a d ia t io n can . In m o s t c a s e s , h o w ev e r, th e d if fe re n c e i s w ith in th e e x p e r im e n ta l e r r o r .

D o s im e try

T h e r a d ia t io n d o se d e l iv e r e d to th e a m m o n iu m b ro m id e p e r p a s s a g e vm der th e s c a n n in g e le c t r o n b e a m is d e te rm in e d by a r ig id PV C fo il d o s i m e te r p la c e d in an e x t r a i r r a d ia t io n can .

PV C w ith o u t p la s t ic iz e r and s ta b i l i z e r g iv e s off H C l p ro p o r tio n a lly to th é a b s o rb e d r a d ia t io n d o se . T h e r e s u l t in g d o u b le b o n d s a r e c o n ju g a te d w hen s u b je c te d to a h e a t t r e a tm e n t o f f h a t 80°C, an d th e a b s o rp t io n a t 395 т ц i s a l in e a r fu nction of th e ra d ia tio n d o se . T he PVC fo il d o s im e te rs h av e b ee n c a l ib ra te d by c o m p a riso n w ith a w a te r c a lo r im e te r .


T h e a b s o lu te r a d ia t io n d o se p e r p a s s a g e w a s d e te r m in e d a t 5. 5 M ra d w ith an e r r o r n o t e x c e e d in g 1 0 %.

T h e n u m b e r o í p a s s a g e s p e r ta in in g to e a c h i r r a d i a t i o n w a s r e c o r d e d b y a m e c h a n ic a l c o u n te r . T h e r e la t iv e d o s e s d e l iv e re d to th e s a m p le s d e pend only on th e s ta b ili ty of th e a c c e le ra to r and a r e b e liev e d to b e t r u e w ith in 1 - 2%.

R e s u lts

Quantities of decomposition products

A su m m a ry i s g iven in T ab le I of a l l h y d ro g en d e te rm in a tio n s c a r r ie d out on th e i r r a d ia te d am m o n iu m b ro m id e s a m p le s .

t a b l e I

HYDROGEN GAS FR O M A C C EL E R A T O R -IR R A D IA T E D AMMONIUM BROM IDE

Radiationdose

(M rad) prim ary

H, cm 3 STP/

secondary

g in

in te rstitia l gas*

H , cm* STP/g original NH4Br

220 0 .0 8 0.01 2 .2 3 2 .32

550 0 .2 4 0 .05 6.17 6.46

1100 0 .59 1.87 11.26 13.66

4400 3 8 .5 13 .3 1.1 52.8

5500 59 .0 6.1 3 .8 68 .4

7700 7 9 .0 4 .4 1 .3 84 .5

11000 90 .2 5 .7 0.2 96.1

* per g ram o f Irradiated sam ple.

A co m p le te m a te r ia l b a lan c e could only be w orked out fo r s a m p le s w ith r a d ia tio n d o s e s up to 1100 M rad . T ab le II g iv e s th e d is t r ib u t io n of a l l d e c o m p o s itio n p ro d u c ts f ro m th e 1100 M rad sa m p le and th e s e d a ta , to g e th e r w ith s im i la r d a ta fo r th e 220 and 550 M rad sa m p le s , w e r e u s e d f o r th e ca lc u la tio n of th e H2 : N 2 r a t io fo r th e decom position re a c tio n

An a v e ra g e v a lu e of H2 : N2 = 3. 84 (v o l./v o l. ) w as found, co rre sp o n d in g to a B r 2 : H B r r a t i o of 5. 20 (w t./w t. ). T h e d is t r ib u t io n of d e c o m p o s itio n p ro d u c ts c a lc u la te d f ro m th e s e v a lu e s i s g iv e n in th e l a s t l in e in T a b le II f o r th e 1100 M ra d sa m p le .

W ith in c r e a s in g r a d ia t io n d o s e a d e c r e a s in g p e r c e n ta g e of th e o th e r d e c o m p o s itio n p ro d u c ts , a s c o m p a re d w ith h y d ro g en , i s found and i t i s no t u n re a s o n a b le to a s s u m e th a t b o th H B r, B r 2 and N2 w ill r e a c t w ith th e a lu m in iu m can u n d e r th e in f lu e n ce of e le c tro n i r r a d ia t io n . T h is i s su p p o rte d

130 К. HEYDORN

TABLE Ц

RADIATION DECOM POSITION PRODUCTS FROM A C C E L E R A T O R -IR R A D IA T E D AMMONIUM BROMIDE

Radiation dose 1100 Mrad Sample Weight 1 g

HBr Br2 Ni H2(mg) (mg) cm 3 STP cm ’ STP

Prim ary gas 0 .5 0.0 0.8 0 .59

Secondary gas - - 0.0 1.87

In terstitia l gas - - 2 .9 11.26

Solid NH4Br 3 .3 18.7 - -

Total 3 .8 18.7 3.7 13.72

C alculated* 4 .1 21 .4 3 .6 -

* Using H2 as reference and H2:N2 = 3 .8 4 .

by th e f a c t th a t , ev e n w ith th e h ig h e s t r a d ia t io n d o s e s , on ly v e r y s m a l l a m o u n ts o f b ro m in e w e r e found in th e p r im a r y g a s .

U n d er th e a s su m p tio n th a t th e H2 : N2 r a t io i s in d ep en d en t of r a d ia t io n d o se , th e in t e r s t i t i a l h y d ro g en c o n ten t p e r g ra m sa m p le can b e c o r r e c te d to h y d ro g en co n ten t p e r g ra m o r ig in a l N H ^B r, and th e to ta l h y d ro g en p r o du c tio n ca n b e c a lc u la te d . T h is is given in th e la s t co lum n of T ab le I, and th e to ta l h y d ro g e n p ro d u c e d a s a fu n c tio n of r a d ia tio n d o se i s r e p r e s e n te d g ra p h ic a lly in F ig . 2.

T he G -v a lu e fo r h yd rogen fo rm a tio n is ca lc u la ted a t 0 .51 m ol. Н2/ЮО eV, and th e in it ia l G -v a lu e fo r NH4B r d ecom position is 0. 27.

Distribution of decomposition products

T h e d is t r ib u t io n of d ec o m p o s itio n p ro d u c ts b e tw e en p r im a ry , s e c o n d a ry , and in te r s t i t i a l g as i s not only dependent on th e ra d ia tio n dose but a lso on th e p r e s s u r e in th e ir ra d ia t io n can and th e tim e in te rv a ls in the an a ly s is .

H o w ev er, so m e g e n e ra l te n d e n c ie s can be o b se rv e d in th e d is tr ib u tio n o f d e c o m p o s i tio n p ro d u c ts in th e so lid p h a s e and T a b le III g iv e s a s u rv e y o f th e a n a ly t ic a l r e s u l t s .

I t a p p e a r s f ro m th e T a b le s th a t , fo r s m a ll d o s e s , th e m a jo r i ty of a l l d e c o m p o s itio n p ro d u c ts i s r e ta in e d by th e c r y s ta l s and th e H 2 : N2 r a t i o in th e i n t e r s t i t i a l g a s i s c lo s e to 3. 84; h o w e v e r, a lw a y s s l ig h t ly s m a l l e r .

W ith l a r g e r r a d ia tio n d o se s th e ca p a b ility of th e c r y s ta l s to r e ta in d e co m p o sitio n p ro d u c ts i s c o n s id e ra b ly red u c e d ; m o re hyd ro g en i s l ib e ra te d th a n i s a c tu a lly b e in g p ro d u c e d and th e r e i s in c re a s in g n itro g e n co n ten t in th e in te r s t i t i a l g as . L ik ew ise , th e B r2 con ten t d e c re a s e s , w h e re a s th e H B r re m a in s n e a r ly unchanged .


0 2000 4000 6000 8000 10000 Mrad

Fig.2

Hydrogen formation from accelerator-irradiated ammonium bromide

REACTOR IRRADIATION

A m m o n iu m b r o m id e s a m p le s o f 0 ,5 g w e r e w e ig h e d in to a lu m in iu m ir ra d ia t io n ca n s w ith a vo lum e of 33 cm3 and a w all th ic k n e s s of 2 m m . The ca n s w e re ev a cu a te d and f ille d w ith h e liu m a t an ас с u r a t e ly - kno wn p r e s s u r e of about 540 m m of m e rc u ry . C ans w e re c lo sed by a r g o n -a rc w elding w hile im m e rs e d in w a te r and f in a lly th e y w e re te s te d w ith a h e liu m le a k d e te c to r .

T h e i r r a d ia t io n c a n s w e re su sp e n d ed in th e s a m e w a te r - f i l le d i r r a d i a t io n tu b e s , a s p re v io u s ly u s e d f o r th e i r r a d i a t i o n of a m m o n iu m b ro m id e , an d th e o r d in a r y h a n d lin g e q u ip m e n t co u ld b e u t i l iz e d .

I r ra d ia tio n w as c a r r ie d out in a th e rm a l n eu tro n flux of about 10lSn /c m 2s an d 7 - r a d ia t io n d o s e - r a t e s o f 107 -1 0 ® r/h . T h e t e m p e r a t u r e o f th e w a te r s u r ro u n d in g th e s a m p le w a s ab o u t 30°C.

A fte r co m p le tio n of th e i r r a d ia t io n th e s a m p le s w e re coo led fo r s e v e r a l w e e k s in o r d e r to r e d u c e th e a c tiv i ty to a le v e l p e r m i t t in g a n a ly s is by th e s a m e p r o c e d u r e s a s a d o p te d f o r th e a c c e l e r a t o r - i r r a d i a t e d s a m p le s .

132 К. HEYDORN

TABLE Ш

DECO M PO SITIO N PRO D U CTS Ш SOLID IRRADIATED AMMONIUM BROM IDE

Radiationdose

(Mrad)Colour

Br as HBr

( mg /g )Bi as Br¡ (m g /g )

Hjcm 3 STP/g

220 lightyellow 1.3 2 .3 2 .23 3 .40

550 yellow 3 .6 10.4 6.17 3.56

1100 carrot 3 .3 18.7 11.26 3.83

4400 yellow 4 16 1.1 0.72

5500lightyellow

2 11 3 .8 0.87

7700whitishyellow

4 7 1 .3 0 .23

11000 w hite 3 5 0.2 0.24

A n a ly s is o f th e i r r a d i a t e d s a m p le s

A fte r coo ling , th e ir ra d ia t io n ca n s w e re pu n ctu red , u s in g a hollow s te e l n e e d le c o n n e c te d to th e g a s s a m p lin g s y s te m a t A in F ig . 1. A s i l ic o n e g re a s e d ru b b e r s to p p e r w as u se d a s w a sh e r betw een th e n ee d le and th e can , and th e sa m e sa m p lin g p ro c e d u re a s d e s c r ib e d p rev io u s ly could be fo llow ed.

A f te r p r im a r y g a s p r e s s u r e e q u i l ib ra t io n and c lo s in g of s to p -c o c k s 3 an d 4 , th e r e s t o f th e g a s in th e cam i s p a s s e d th ro u g h th e w a s h -b o t t le by open ing n e e d le -v a lv e 2. T he s y s te m is th e n d is a s se m b le d , and a n a ly s is of th e p r im a r y g a s ca n b e c a r r i e d out a s p re v io u s ly d e s c r ib e d .

Im m e d ia te ly a f te r co m p le tio n of th e p r im a ry g as sa m p lin g th e i r r a d i a t io n c a n i s c u t r ig h t th ro u g h and p a r t o f th e s o lid a m m o n iu m b r o m id e i s w eighed in to a p ip e tte con ta in ing a known am ount of a i r a t am b ien t te m p e r a t u r e an d p r e s s u r e . A fte r a c o u p le of d a y s s e c o n d a ry g a s i s d e te r m in e d r e l a t i v e to a i r b y m a s s - s p e c t r o m e t r y .

T he r e s t o f th e so lid am m onium b ro m id e is d isso lv ed in w a te r and an aly s e d f o r B r 2 and H B r a s d e s c r ib e d p re v io u s ly .

F o r d e te r m in a t io n of i n t e r s t i t i a l g a s , th e g a s in th e p ip e t te w a s e x ch a n g ed w ith h e liu m a t an a c c u ra te ly -k n o w n p r e s s u r e of ab o u t 250 m m of m e r c u r y an d th e q u an tity and c o m p o s itio n of th e l ib e r a te d g a s d e te rm in e d a s p r e v io u s ly d e s c r ib e d .


D o s im e try

T h e e n e rg y a b s o rb e d by th e am m o n iu m b ro m id e d u r in g r e a c to r i r r a d ia t io n i s d e te r m in e d by th e in te g r a te d th e r m a l n e u tro n flu x , f a s t n e u tro n f lu x and 7 - f lu x .

E ac h i r r a d ia t io n w as equ ipped w ith n e u tro n d o se m o n ito rs , co b a lt w ire fo r th e rm a l n e u tro n s and n ic k e l w ire fo r fa s t n e u tro n s , th u s giving ind iv idual v a lu e s fo r th e s e p a ra m e te r s .

T h e 7 - f lu x cou ld n o t b e m e a s u re d fo r th e in d iv id u a l s a m p le s b u t had to b e e s t im a te d f ro m p re v io u s c a lo r im e tr ic m e a s u re m e n ts of 7 -h e a tin g in a lu m in iu m . T h e s e v a lu e s w e re c o r r e c te d f o r d if fe r e n c e s in s a m p le lo c a tio n and th e rm a l n eu tro n flux , but th e re su lt in g e s tim a te s m ay not be too re lia b le .

T h e rm a l n e u tro n s im p a r t e n e rg y to m a t te r on ly w hen c a p tu re d and th e r e s u l t in g co m p o u n d n u c le u s e m its p r o m p t 7 - r a d ia t io n fo llo w e d b y r a d i o iso to p e d ec ay . P a r t of th e e n e rg y d is s ip a tio n i s th u s d e la y e d a c c o rd in g to th e h a l f - l i f e of th e ra d io n u c lid e s fo rm e d . S ince in v e s tig a tio n s of i r r a d ia te d am m onium b ro m id e a r e postponed u n til a lm o s t com ple te decay of b ro m in e -82, th e to ta l e n e rg y d is s ip a t io n f ro m ra d io is o to p e d e c a y h a s b e e n in c lu d e d in th e c a lc u la t io n o f r a d ia t io n d o se f ro m th e r m a l n e u tro n s .

G am m a r a d ia t io n t r a n s f e r s e n e rg y to m a t t e r by e le c t r o n in te r a c t io n , an d th e e n e rg y a b s o rp tio n v a r i e s on ly l i t t l e f ro m s u b s ta n c e to s u b s ta n c e . W h e re n o know ledge of th e 7 - s p e c t r u m i s a v a ila b le , th e e n e rg y a b s o rp tio n p e r g r a m of am m o n iu m b ro m id e h a s b e e n s e t eq u a l to th a t o f a lu m in iu m .

C o n tra ry to th e p re c e d in g p r o c e s s e s , th e s low ing down of f a s t n eu tro n s c o n fe rs en e rg y d ire c tly on th e n u c le i, e sp e c ia lly th e lig h t ones. In th e ca lc u la tio n of e n e rg y a b so rp tio n f ro m f a s t n e u tro n s , th e in te ra c t io n w ith b ro m in e n u c le i h a s b ee n d is re g a rd e d .

T a b le IV l i s t s th e 7 - and n e u tro n f lu x e s f o r e a c h i r r a d ia t io n to g e th e r w ith th e c a lc u la te d r a d ia t io n d o s e s in M rad .

R e s u lts

A s u m m a ry i s p r e s e n te d in T a b le V of a l l h y d ro g e n d e te rm in a tio n s c a r r i e d out on th e r e a c to r - i r r a d i a t e d s a m p le s .

A c o m p le te m a te r ia l b a la n c e cou ld on ly b e e s ta b l is h e d f o r s a m p le 1S2. T h is s a m p le g iv e s a H 2 : N 2 r a t i o o f 3. 75 an d th i s v a lu e h a s b e e n u s e d f o r th e c o r r e c t io n of s e c o n d a ry and in t e r s t i t i a l h y d ro g e n p e r g r a m i r r a d ia te d sa m p le to h y d ro g en p e r gpam o r ig in a l am m o n iu m b ro m id e fo r a l l s a m p le s .

T h e to ta l, h y d ro g e n fo rm a tio n p e r g ra m is s ta te d in th e l a s t co lu m n in T a b le V and th e th r e e g ro u p s of r e s u l t s a r e p lo tted to g e th e r a g a in s t th e to ta l c a lc u la te d ra d ia tio n d o se in F ig . 3.

C o n c e rn in g th e d is t r ib u t io n of d e c o m p o s i tio n p ro d u c ts in th e r e a c t o r i r r a d ia t io n s th e s a m e g e n e ra l te n d e n c ie s w e re o b se rv e d a s in the ' a c c e le r a to r i r r a d ia t io n s . G e n e ra lly , a l a r g e r p a r t of th e f r e e b ro m in e w as found, s in c e th e a n a ly s is o f th e so lid am m o n iu m b ro m id e w a s c a r r i e d ou t b e fo re r e l e a s e s of s e c o n d a ry g a s . B ro m in e c o n te n ts up to 95 m g /g of am m o n iu m b ro m id e s a m p le w e r e r e c o r d e d , b u t d e ta i le d r e s u l t s a r e n o t g iv e n in th is p a p e r .

TABLE IV

Irrad iation(No)

Irrad iationtim e(h)

Irrad iation conditions R adiation dose

y -h e a tin g m W /g' Al

th e rm a l fluxPF*

fast flux PF*

y -dose (M rad)

th e rm a l dose (M rad)

fast dose (M rad)

to ta l dose (M rad)

1S1 4 8 .0 45 109 4 .8 780 1120 70 1970

‘¿Si 100.0 40 90 3 .7 1480 1930 120 3530

1S2 5 .0 330 161 2 4 .3 610 170 40 820

2S2 10.0 310 141 1 9 .8 1140 310 60 1510

3S2 20.0 360 189 3 2 .0 2600 810 210 3680

1S4 70 .0 115 7G 4 .7 3300 1140 100 4600

2S4 140 .0 150 123 C. 5 7740 3700 290 11730

* P P (p íle factor) = 10u n /c m 2s.

TABLE V

HYDROGEN GAS FRO M R EA C TO R -IR R A D IA TED AMMONIUM BROM IDE

EXPERIENCES WITH THE IRRADIATION ОТ AMMONIUM BROMIDE 135

Irradiation(No)

prim ary

H2 cm 3 STP/g

secondary*

in

in terstitia l gas*

H2 cm 3 STP/g original NH4Br

1S1 10.54 0 .28 11.22 22.0

2S1 8 .42 32 .4 0 .62 40 .3

1S2 1 .38 5. 75 9.17 26.24

2S2 22.8 2 .73 4 .! « .30.0

3S2 68.1 3.07 0. 85 71.5

1S4 89.2 3.01 0.71 92.5

2S4 198 2.60 0 .05 200

* per gram of irradiated sam ple.

I n te r p r e ta t io n of r e s u l t s

T h e r e s u l t s a s show n in F ig . 3 ex h ib it a l in e a r d ep e n d en c e on to ta l r a d ia tio n d o se in a l l t h r e e s e r i e s , in s p i te of c o n s id e r a b le v a r ia t io n s in th e c o m p o s itio n o f th e c a lc u la te d d o se b e tw een th e s e r i e s . T a b le VI g iv e s th e a v e ra g e c o m p o s itio n o f th e d o s e s to g e th e r w ith th e G(H2 ) v a lu e s , and th e G (-N H 4 B r) v a lu e s b a s e d on a H 2: N2 r a t i o o f 3. 75.

T h e o b s e rv e d G(H 2 ) v a lu e s c a n b e e x p r e s s e d a s a l in e a r c o m b in a tio n of G -v a lu e s fo r th e rm a l n e u tro n s , f a s t n e u tro n s , and 7 - ra d ia t io n , th e th r e e r e s u l t in g e q u a tio n s b e in g su f f ic ie n t to d e te rm in e th e s e f ig u re s . U n fo r tu n a te ly , th e G -v a lu e f o r f a s t n e u tro n s a p p e a r s n e g a tiv e , th u s d e m o n s tr a tin g la c k of c o m p a tib ili ty b e tw e e n th e s e r i e s .

S in ce аП m e a s u r e m e n ts o f th e r m a l n e u tro n f lu x an d f a s t f lu x f o r th e in d iv id u a l s a m p le s w e re c a r r i e d ou t a t on e t im e , th e c o r re s p o n d in g d o s e s

sh o u ld b e c o n s is te n t . T h e 7 - d o s e s , h o w e v e r , w e r e b a s e d on tw o s e t s of m e a s u r e m e n ts , one b e in g u s e d f o r th e S2 and S4 i r r a d ia t io n s and a n o th e r f o r S I. I t i s no t u n re a s o n a b le to b e lie v e th a t th e y m ay h av e d if fe re n t c a l i b ra t io n e r r o r s .

T h e in tro d u c tio n of th is new v a r ia b le m a k e s th e e q u a tio n s in d e f in ite , b u t th e s im p le s ta te m e n t th a t sill G -v a lu e s m u s t b e p o s itiv e l im its th e ra n g e to G therm al ~ ^“0. 9 and Gfast 0 . 2 .

T h e se f ig u re s a r e only in c lu d ed to in d ic a te th e p ro b a b le o r d e r of m a g n itu d e and m u s t no t be ta k e n fo r a c tu a l d e te rm in a tio n s .

DISCUSSION

T h e r a d ia t io n d e c o m p o s i tio n o f am m o n iu m b ro m id e , to g e th e r w ith a n u m b e r of o th e r .c o m p o u n d s , h a s r e c e n t ly b e e n in v e s t ig a te d b y T A Y L O R

136 К. HEYDORN

О 2000 4000 6000 8000 ЮООО Mrad

Fig.3

Hydrogen formation from reactor-irradiated ammonium bromide

%

TABLE VI

Series SI S2 S4* A ccelerator

T herm al/fast 16 4 .4 11 -

у -dose (%) 41 74 73 100

G (H2) 0 .49 0.85 0.87 0.51

G (-N H 4Br) 0 .26 0.45 0 .46 0.27

* Om itting 2S4 because it is beyond the linear part o f the graph.


and ROGERS [2] f ro m a lm o s t th e s a m e p o in t o f v iew a s in th is w o rk . T h e r a d ia t io n d o s e s w e r e c o n s id e r a b ly s m a l l e r an d no r e a l d e te r m in a t io n o f G -v a lu e s w as a tte m p te d . I t w as found th a t th e f a s t n e u tro n flux co n trib u ted s ig n if ic a n tly to th e to ta l d ec o m p o sitio n .

A re c a lc u la t io n of th e e x p e rim en ted v a lu e s of T a y lo r and R o g e rs in d ic a te s th a t th e i r r e s u l t s , w ith a s in g le ex cep tio n , f a l l b e tw e en th e tw o l in e s in F ig . 3, w h ich m e a n s th a t t h e r e i s r e a s o n a b le a g r e e m e n t in th e r e g io n below 5-600 M rad . T he r e s u l t s of th e p r e s e n t w ork , h o w ev er, do not show any a p p re c ia b le in f lu e n c e of f a s t n e u tro n s , a s in d ic a te d by th e sm o o th n e s s w ith w h ich th e S2 and S4 s e r i e s lin k up . T h e g e n e ra l ly h ig h e r p e rc e n ta g e of 7 -d o s e in o u r e x p e r im e n ts , h o w ev e r, te n d s to o b s c u re th e e ffe c t of f a s t n e u tro n s .

No G -v a lu e fo r f a s t n e u tro n s can be a s s ig n e d f ro m th e p r e s e n t e x p e r im e n ts , b u t i t i s u n lik e ly to b e m u c h h ig h e r th a n f o r th e r m a l n e u t ro n s and 7 - r a d ia t io n .

T he G -v a lu e fo r 7 - ra d ia t io n i s c o n s id e re d equal to th e v a lue d e te rm in e d by e le c tro n ir ra d ia t io n , i. e. G(H2 ) = 0. 51± 0. 05 m ol. Н2/ЮО eV.

T h e G -v a lu e f o r th e r m a l n e u t ro n s m u s t b e g r e a t e r th a n , o r eq u a l to , th e G -v a lu e fo r 7 - ra d ia t io n . T he e n e rg y a b so rp tio n re s u lt in g f ro m th e rm a l n e u tro n c a p tu r e i s t r a n s f e r r e d a lm o s t e x c lu s iv e ly b y 0 - p a r t i c l e s an d 7 - ra d ia tio n , th e n u c le a r r e c o i l e n e rg y b e in g n e g lig ib le in c o m p a riso n .- H ow e v e r , th e r e l e a s e on o n e m o le c u le of h y d ro g e n f ro m a m m o n iu m b r o m id e r e q u i r e s on ly 1 .4 eV , so th e G -v a lu e fo r n u c le a r r e c o i l m a y a p p ro a c h 70. T h e r e c o i l e n e rg y i s l e s s th a n 2° / о о of th e to ta l th e r m a l n e u tro n d o se and th e co n trib u tio n to th e to ta l G -v a lu e i s , th e re fo r e , d e fin ite ly l e s s th an 0 .1 4 . C onsequen tly , th e G -v a lu e fo r th e rm a l n e u tro n s can b e e x p re s s e d a s G(H2) =0. 58 ± 0 .1 2 .

CONCLUSION

T h e r a d ia t io n d e c o m p o s itio n o f am m o n iu m b ro m id e h a s b e e n in v e s t i g ated u s in g n o rm a l iso to p e p ro d u c tio n fa c i l i t ie s in DR2 and a l in e a r e le c tro n a c c e le r a to r . R e s u l ts f ro m a c c e le r a to r i r r a d ia t io n s g ive a GCH2) v a lu e fo r e l e c t r o n an d 7 - r a d ia t io n o f 0. 51 an d a G ( -N H J 3 r ) v a lu e of 0. 27. R e a c to r i r ra d ia t io n s in d ic a te d l i t t le in flu en ce f ro m f a s t n e u tro n s bu t no d efin ite conc lu s io n s c o u ld b e d ra w n b e c a u s e of d o u b tfu l 7 - r a d ia t io n m e a s u r e m e n ts .

H ydrogen fo rm a tio n v a r ie d l in e a r ly w ith to ta l ab so rb e d dose up to about 6 ÔÔÛ M rad , bo th fo r r e a c to r - i r r a d ia te d and a c c e le r a to r - i r r a d ia te d am m onium b ro m id e .


I sh o u ld l ik e to acknow ledge th e e n c o u ra g in g h e lp and u s e fu l ad v ice g iv en to m e b y D r. K. A. S in g e r and M r. E lf in n L a r s e n and I am in d e b te d to M r. H. B okelund and M r. A. V in th e r, o f th e M a ss S p e c tro m e try G roup , f o r p e r fo rm in g th e n u m e ro u s g a s a n a ly s e s , an d to M r. H. T h e i lg a a rd fo r th e o th e r a n a ly tic a l d e te rm in a tio n s .

138 К. HEYDORN

R E F E R E N C E S

[1] HEYDORN, К ., Ingeni0ten Int. Ed. 4 (1960) 78.[2] TAYLOR. K .J. and ROGERS, G .T ., AERE-R 3409 (1962).

D I S C U S S I O N S

C. TAYLOR (C h airm an ): T h is p a p e r i l l u s t r a te s th e com plex ity of th er a d ia t io n -c h e m ic a l p r o c e s s e s o c c u r r in g in r e a c to r ir ra d ia t io n , and show s how d if f ic u lt i t i s , ow ing to g a s ev o lu tio n , to f in d a q u a n t ita tiv e b a s i s fo r d e c is io n s re g a rd in g th e sa fe ty of s a m p le s su b m itte d fo r ir ra d ia t io n . W hat c o n c lu s io n s h a v e you re a c h e d abou t th e co n d itio n s u n d e r w hich am m o n iu m b ro m id e m a y b e i r r a d ia te d sa fe ly ?

K. HEYDORN: F o r ir ra d ia t io n of so lid NH4B r u n d e r given ir ra d ia tio nco n d itio n s, th e f ig u re s in the p a p e r w ill p e rm it a good e s tim a te of the fo rm a tio n of g a s e s by r a d ia t io n d ec o m p o sitio n , and th e m a x im u m p r e s s u r e in an i r r a d ia t io n can i s e a s i ly c a lc u la te d .

H ow ever, ir ra d ia t io n cond itions a r e U sually not v e ry w ell known, e s p e c ia lly w ith r e g a rd to 7 - ra d ia t io n , and the e s tim a te d gas p r e s s u re m ay th e re fo re be of l i t t le va lue .

T he sa fe p ro c e d u re i s to d e te rm in e th e to ta l gas fo rm a tio n f ro m NH4B r by a sh o r t te s t - i r r a d ia t io n in th e fa c ility co n cern ed . The g rap h s in th e p ap e r show th a t th e g a s fo rm a tio n i s a l in e a r fu n c tio n o f r a d ia t io n d o se , i . e . of i r ra d ia t io n tim e , and a s in g le d e te rm in a tio n is , th e re fo re , su ffic ien t. Howe v e r , i t m u s t b e r e m e m b e re d th a t in s h o r t- t im e i r r a d ia t io n s th e m a in p a r t o f th e g a s e s r e m a in s in th e s o lid p h a s e , and n e g le c t of th e i n te r s t i t i a l g a s m a y le a d to a v e r y s e r io u s u n d e r e s t im a tio n of th e g a s p r e s s u r e in a f u l l t im e i r r a d ia t io n .

C. TAYLOR: W hat d id you dec ide? H ave you dec ided upon a co n ta in e rand a quan tity?

K. H EYD O RN : W e h a v e n o t d e c id e d an y th in g so f a r . I go t th e l a s tr e s u l t s only a few days ago, so we have not y e t had tim e to m ake a d ec is io n . T h is is up to th e sa fe ty c o m m itte e of th e D an ish r e a c to r DR2 and th e y have n o t y è t r e c e iv e d th e r e s u l t s .

C. TAYLOR: H ave you c o n s id e re d i r r a d ia t in g in a v en ted c o n ta in e r?K. HEYDORN: It i s v e r y u n p le a s a n t w ith open c o n ta in e rs b e c a u s e of

th e r e le a s e Of f r e e b ro m in e and h yd rogen b ro m id e , w hich would con tam inate th e a i r to a v e ry u n p le a sa n t ex ten t.

G. COURTOIS: A lthough I u n d e rs ta n d th a t M r. H eydorn has not c a r r ie do u t i r r a d ia t io n of NH4 B r in so lu tio n , I w ould l ik e to m e n tio n th a t a t S ac lay we have now b een ir ra d ia t in g NH4B r in so lu tion fo r ov er a y e a r . The advanta g e s o f th is a r e th a t one ca n av o id th e S z i la rd e f fe c t ( s in c e th e NH4B r i s d ec o m p o sed ) and one can a lso avo id th e r e le a s e of oxygen due to r a d io ly s is of th e w a te r (s in c e th e B r in te r c e p ts th e f re e r a d ic a ls ) . I am in te r e s te d in th i s q u e s tio n , and if any o n e e l s e h a s p e r f o rm e d i r r a d ia t io n s of NH4 B r in so lu t io n I w ou ld b e v e r y h ap p y to d is c u s s i t w ith h im .

I w ould now lik e to a s k M r. H eydorn w h e th e r , in h is d o se c a lc u la tio n s , h e h a s ta k e n in to a c co u n t th e s h o r t - l iv e d is o to p e s p ro d u c e d in th e r e a c to r , f o r in s ta n c e 1 8 -m in B r 80 and N 1̂ .


K. HEYDO RN: O u r d o s e c a lc u la t io n s w e r e c a r r i e d ou t ta lc ing in toac co u n t a l l r a d io a c t iv e d ec ay f ro m a l l r a d io is o to p e s p ro d u c e d by th e i r r a d ia tio n of ТТЩВг, e . g. th e s h o r t- l iv e d b ro m in e iso to p e s a s w ell a s th e 36 -h b r o m in e - 82. T h e d e c a y in n i t r o g e n - 16 i s in c lu d e d in o u r c a lc u la t io n s of c a p tu re -g a m m a r a d ia t io n d o se , b e c a u s e i t i s so s h o r t- l iv e d . A s c o n c e rn s th e n u c le a r r e c o i l , w e m a d e a m a x im u m e s t im a te , w h ich tu r n e d ou t to b e l e s s th a n 0 . 2% of th e to ta l th e r m a l n e u tro n d o se , so th a t e v e n w ith a v e r y la r g e G—v a lu e fo r n u c le a r r e c o i l th e e ffec t on th e to ta l G -v a lu e fo r -th erm a l n e u tro n s w ould b e v e ry sm a ll .

L . G. ER W A LL: F o r th e p ro d u c e r of r a d io is o to p e s th e r a d ia t io n d e c o m p o s itio n of N H 4 B r i s , o f c o u r s e , o f g r e a t im p o r ta n c e . F o r th e u s e r , how ever, th e c h e m ic a l s ta te of th e B r 82 i s of p r im a ry in te r e s t . R ecen t p r e l im in a ry e x p e r im e n ts (L a r s G. E rw a ll, T . E r ik s s o n , unpub lished ) in d ic a te th a t a s m u c h a s 90% of th e B r 82 c a n b e p r e s e n t a s e l e m ta r y B r . F o r th is re a s o n we now p re p a re o u r B r82 t r a c e r so lu tio n s by d isso lv in g th e ir ra d ia te d N H 4 B r in a N a 2 S 2 0 3 so lu tio n , to re d u c e B r in to B r ' . H ave any s tu d ie s of th e s ta te of th e ra d io a c tiv e B r b ee n p e r fo rm e d in connection w ith th e r a d ia tio n d ec o m p o s itio n s tu d ie s you have r e f e r r e d to in y o u r p a p e r?

K. HEYJDORN: T h e c h e m ic a l s ta te o f r a d io a c t iv e B r 82 h a s n o t b e e nin c lu d e d in o u r s tu d ie s , b u t I a g r e e w ith M r . E r w a l l th a t a l a r g e p a r t i s u n d o u b te d ly p r e s e n t a s e le m e n ta ry b ro m in e , and th a t d is s o lu tio n o f i r r a d ia te d NH4B r sh o u ld ta k e p la c e in a re d u c in g m e d iu m .

I h o p e w e s h a l l b e a b le to c o n tin u e th e in v e s t ig a t io n o f th e r a d ia t io n d e c o m p o s itio n of NH4B r in c o -o p e ra t io n w ith o u r ra d ia t io n c h e m is ts , who a r e in te r e s te d in stu d y in g th is c a s e f ro m a m o re fu n d am e n ta l p o in t of view .

CONTRIBUTION A L ’ÉTUDE DE LA PRÉPARATION DU TELLURE-132 ET DE L ’IODE-132

R. STIENNON-BOVY ET G. HAEGEMAN-GELADI CENTRE D'ÉTUDE DE L'ÉNERGIE NUCLÉAIRE, MOL, BELGIQUE


PREPARATION OF TELLURIUM-132 AND IODINE-132. By means of synoptic tables the authors of the paper reca ll the methods described in the lite ra tu re for isolating tellurinm -132 from irradiated uranium and fission products and for separating iodine-132 from tellu rium -132 . They specify the conditions in which the tellurium -132 and the iodine-132 have to be obtained and give experim ental details on how these conditions can be a tta in ed using a lum ina chrom atography both for iso la ting the te llu rium -132 and for separating the iodine-132 therefrom (e ffec t of the am ount of entraining agent and of tem perature , to lerance of im purities, e tc ) .

The authors have also studied the com position and s tab ility of entrain ing ag en t-free solutions of te l- lu rium -132 and iod ine-132 and com pare d ifferent methods of calib ra ting both solutions.

A descrip tion is given of the c e l l in tended for th e production o f 500 m e of te llu riu m -1 3 2 per run.Shielding, which can be used for transport and storage purposes and during use óf the chrom atography

colum nsiloaded witji rad ioactive substances, is also described.The authors have labe lled serum album in with iodine-132 using the V eall m ethod; the preparation of

iodine-132 and the labelling of proteins can easily be carried out by the user him self within a tim e compatible with the ha lf-life of the isotope.

CONTRIBUTION A L'ETUDE DE LA PREPARATION DU TELLURE-132 ET DE L'IODE-132. Les auteurs rappellen t par des tab leaux synoptiques les m éthodes décrites dans la litté ra tu re pour iso ler le te llu re -1 3 2 de lf uranium irradié e t des produits de fission e t pour séparer l'iode-132 du tellure-132. Ils précisent les conditions dans lesquelles le tellure-132 e t l*iode-132 doivent être obtenus e t donnent des détails expérimentaux qui p e rm e tten t d 'a tte in d re ces conditions en app liquan t la chrom atographie sur a lum ine aussi b ien pour isoler le tellure-132 que pour en séparer l'iode-132 (influence de la quantité d 'entraînenr, de la tem pérature, to lérance pour les im puretés).

Les auteurs ont étudié égalem ent la composition e t la stabilité des solutions sans entraîneur de tellure-132 e t celles d 'iode-132 e t com parent différentes méthodes pour étalonner les solutions de te llu re-132 e t celles d 'iode-132 .

La ce llu le prévue pour la production de 500 m e de te llu re-132 par cam pagne est décrite .Les auteurs décrivent une pro tection biologique pouvant servir à la fois au transport, au stockage e t à

l*utilisation des colonnes de chrom atographie chargées de substances radioactives.Us ont marqué l'album ine de sérum avec de l'iode-132 en appliquant la méthode de Veall; la préparation

de l liode-132 e t le m arquage des protéines peuvent ê tre a isém ent réalisés par l'u tilisa teu r lu i-m êm e dans un tem ps com patib le avec la période de l'iso tope .

ВКЛАД В ИЗУЧЕНИЕ ПРОБЛЕМЫ ИЗГОТОВЛЕНИЯ ТЕЛЛУРА-132 И ЙОДА-132. Приводя синоптические таблицы, авторы возвращаются к описанным в литературе методам изоляции теллура-132 от облученного урана и расщепляющихся материалов и отделения йода-132 от теллура-132. Они уточняет условия получения теллура-132 и Йода-132 и подробно излагают опыты, в которых применение хромотографии на глиноземе позволяло не только изолировать теллур-132, но и выделять йод-132(воздействие количества носителя, температуры, допуска примесей и т.д.).

Авторы исследуют такхе состав и устойчивость без носителей растворов теллура-132 и йода-132 и сравнивают различные методы эталонирования данных растворов.

Описывается камера для получения 500 милликюри теллура-132 по кампаниям, а такхе биологическая защита, которая мохет быть одновременно использована при транспортировке, хранении на складах и применении хромотографических колонок с радиоактивными веществами.

По методу Велла проведено мечение сыворотки белка йодом-132; изготовление йода-132 и мечение протеина мохет быть легко исполнено самим потребителем за время, сравнимое с периодом хизни изотопа.

141

142 R. STIENNON-BOVYetG. HAEGEMAN-GELADI

CONTRIBUCIÓN AL ESTUDIO DE LA PREPARACIÓN DEL TELURO-132 У DEL YODO-132. Los autores ilustran con cuadros sinópticos los métodos descritos en la b ib liografía para a islar e l te lu ro-132 de l uranio irrad iado y de los productos de fisión, y para separar e l yodo-132 del te lu ro -132 . D efinen las condiciones de obtención del te luro-132 y del yodo-132 y describen detalles experim entales que perm iten alcanzar estas condiciones ap licando la crom atografía sobre a lúm ina tan to para aislar e l te lu ro -132 com o para separarlo del yodo-132 (influencia de la cantidad de portador, de la tem peratura, tolerancia para las im purezas, e tc .) .

Por otra parte, los autores han estudiado la composición y la estabilidad de las soluciones del teluro-132 y del yodo-132, ambos libres de portador, y comparan diversos métodos para calibrarlas. La m em oria describe una celda diseñada para producir 600 me de telurio-132 en cada operación. Describe tam bién una protección biológica que puede servir para e l transporte, e l alm acenam iento y la u tilización de las columnas de croma** tografía cargadas de sustancias radiactivas*

Los autores han marcado seroalbúmina con yodo-142 aplicando e l método de Veall; e l propio experimentador puede fácilm ente preparar e l yodo-132 y m arcar las proteínas en un tiem po com patible con e l período del isótopo.

1. INTRODUCTION

N ous av o n s d é jà m is en é v id en c e l e s a v a n ta g e s que p r é s e n te l 'u t i l i s a tio n d e l 'io d e - 1 3 2 (2 ,4 h) e t la p o s s ib i l i té d 'u t i l i s e r c e t is o to p e m a lg r é sa v ie c o u r te lo in d ' u n c e n tre de p ro d u c tio n de ra d io iso to p e s en le s é p a ra n t d e son p a re n t , le t e l l u r e - 132 (77 h), au m o m en t où l ' o n so u h a ite l 'u t i l i s e r [11. D e n o m b re u s e s p u b lic a t io n s té m o ig n e n t de l 'e m p l o i t r è s l a r g e de 1 ' io d e -1 3 2 .p o u r d e s a p p l ic a tio n s m é d ic a le s n o ta m m e n t [2].

N ous avons é ta b li deux n o m o g ram m es qui p e rm e tte n t, e n t re a u t re s , de d é te rm in e r l 'a c t iv i t é A du te llu re -1 3 2 dont i l fau t d isp o se r s i pendent n jo u rs , m oyennan t m sé p a ra tio n s p a r jo u r , on veu t s 'a s s u r e r , so it chaque jo u r une a c tiv i té d ' i o d e - 132 au m o in s ég a le à une a c tiv ité donnée a, so it chaque jo u r u n e c e r ta in e a c t iv i té d ' i o d e - 132 qu i, au to ta l , r e p r é s e n te u n e a c t iv i té d o n n é e s [3].

C e m é m o ir e c o n s ti tu e u n e c o n tr ib u tio n à l 'é t u d e de la s é p a r a t io n du te llu re -1 3 2 d es a u tre s p ro d u its de f is s io n des a to m es lo u rd s , 1 'u ran ium -235 n o ta m m e n t, e t à 1' é tude de l a s é p a ra tio n de 1' io d e - 132 du te l lu r e - 1 3 2 . L a f is s io n de 23E>u donne n a is s a n c e au x p ro d u its de f is s io n su iv a n ts [4]:

i32sb _____► ̂ 1*̂ 1 ____ *■(1.9 m in) (77 h) (2,4 h) (stable)

132Xe (12 J)

1311 *4% !(8.05 j) ^ +i3iXe

(stable)

D es c o n d itio n s d 'i r r a d i a t i o n e t d e d é s a c t iv a t io n de l 'u r a n iu m * d é p e n d ra la co n tam in a tio n du te l lu re -1 3 2 p a r le s a u t re s te l lu r e s ra d io a c tifs ; de ce tteco n tam in atio n e t de la d u ré e qui s 'é c o u le r a e n tre deux sé p a ra tio n s de l 'io d ee t du t e l l u r e d é p e n d ra l a c o n ta m in a tio n de l ' i o d é - 132 p a r l e s a u t r e s i s o

1 3 1 Т е (30 h)

is iT e -(24,8 m in)

* Les périodes radioactives des parents des tellures é tan t courtes, nous pouvons pratiquem ent ne pasfaire de d istinction entre désactivation de l'u ran ium e t évolution propre des tellures.

PRÉPARATION DU TELLURE-132 ET DE L*IODE-132 143

to p e s r a d io a c t i f s d e l ' i o d e . P ra t iq u e m e n t , s e u l le t e l l u r e - 131 e t p a r l à l 'io d e -1 3 1 do iven t ê t r e c o n s id é ré s com m e co n tam in an t du te l lu re -1 3 2 e t de l ' i o d e - 132.

L a con tam ination de l 'a c t iv i t é de l 'io d e -1 3 2 p a r 1' a c tiv ité de l 'io d e -1 3 1 s 'e x p r im e en pou r cen t p a r la re la tio n su ivan te :

АШ1 /А "*1 = R • S (1)

avec

1 ^ ( 1 - e " 4 T) e 'M 1

R -----------------------------»г 1( 1 - е " лч т) e " M

X ^ - X j ) e - KT-e -KrS = 10-2------------------------------------- ,

^2(^2 " ^ 1) e - ^ 1- e -^ 2T

r*: re n d e m e n t de f is s io n du 132 T e , r*i: re n d e m e n t d e f is s io n du i? iT e (30 h),Xj: c o n s ta n te r a d io a c tiv e d u 132T e,X2 : con stan te rad io a c tiv e du 132I,X'j: c o n s ta n te ra d io a c t iv e d u i3 iT e (30 h),X'2 : c o n s ta n te ra d io a c t iv e du 131I,T : te m p s d 1 i r r a d ia t io n , t : te m p s d e d é s a c tiv a tio n ,t : tem ps qui s 'é c o u le en tre deux sép ara tio n s de l 'io d e du te llu re (c e lle s-c i

sont su p p o sées to ta le s).L a f ig u re 1 d onne l a v a l e u r d e S, c ' e s t l e r a p p o r t d e s a c t iv i té s d e s

io d es-1 3 1 e t -132 ex p rim é en p o u r ce n t qui s e re fo rm e n t pendant le te m p s т à p a r t i r d 'a c t iv i té s é g a le s de te llu re s -1 3 1 e t -132 a p rè s une sé p a ra tio n c o m -

r (h )

Figure 1

Valeur de S en fonction d e r .

144 R. STIENNON-BOVY et G. HAEGEMAN-GELADI

p lè te . L a f ig u re 2 donne la v a le u r de R qui e s t l e r a p p o r t d e s a c tiv i té s d es t e l l u r e s - 131 e t -132 p r é s e n te s quand de l 'u r a n iu m - 2 3 5 e s t i r r a d ié e t d é s a c tiv é pendan t r e s p e c t iv e m e n t T e t t h e u re s . E n ap p liq u an t la fo rm u le (1), on tro u v e p a r exem ple que lo rsq u e d 'u n e s o u rc e de t e l l u r e - 132, e l le -m ê m e is o lé e d 'u r a n iu m - 235 i r r a d ié pendant se p t jo u rs e t d é sa c tiv é pendant q u a tre jo u r s , on e x t r a i t l ' i o d e - 132 a lo r s q u 'u n e ¡sépara tion d 'io d e -1 3 2 a é té fa ite douze h e u re s au p a rav an t, l 'a c t iv i t é de l 'io d e -1 3 1 qui accom pagne l 'a c t iv i t é d e l ' i o d e - 132 c o r r e s p o n d à 0, 1% d e c e l l e - c i . L a p a r t i e du n o m o g ra m m e r e la t iv e au t e l l u r e - 132 p e rm e t de d é te rm in e r l 'a c t i v i t é e x p r im é e en m e de ce te l lu r e p ré s e n t dans 1 g d 'u ra n iu m n a tu re l i r r a d ié dans un flux lO ^ /c n & s pendan t T h e u re s e t d ésa c tiv é pendant t h e u re s .

132 ,. 131T.

Г I

Г— «00

— 200

— 100

— 50

F" 10

— 1

— 0,1

0Д1

r - 10

— 100- - 4— 200 10 —I

- 3 1— 10

- 2 ï— 400 10 —

1o‘ 1 J

I— 10

Figure 2

- S0

- 100

- 200 <00

— 200

— 100

- 60

- 20 10

NomogrammePour obtenir R il faut:a) aligner les valeurs fixées pour T e t t pour obtenir un point sur les échelles A relatives au u*Te e t au 131Te; b) aligner les points trouvés sur les échelles A pour obtenir la valeur R.

P a r l a f ig u re 3 n o u s r a p p e lo n s q u ' i l fa u t p ra t iq u e m e n t d o u ze h e u r e s p o u r q u e l 'é q u i l i b r e r a d io a c t i f s o it a t te in t lo r s q u e l ' i o d e - 132 e s t s é p a r é d e so n p a r e n t .

2. P R É P A R A T IO N DU T E L L U R E -132

2 .1 . V ue d 'e n s e m b le d e s m é th o d e s de p r é p a r a t io n

L e s m é th o d e s de s é p a ra tio n du te l lu re -1 3 2 de l 'u r a n iu m e t d e s a u t r e s p r o d u i ts d e f i s s io n a c tu e l le m e n t c o n n u e s so n t d é c r i t e s au ta b le a u I.

PRÉPARATION DU TELLURE-132 ET DE L'IODE-132 145

TEMPS (h)

Figure 3

Variation,en fonction du temps>du rapport des activités de l'iode-132 et du tellure-132 (la séparation est supposée complète au temps 0).

TABLEAU I

M ÉTH OD ES DE SÉPA RA TIO N DU T E L L U R E -132

Principe Entraîneur Rendement chim ique Contam inant

Précip itation de TeO¡ [5] x 80% -

Précip itation de T e [6] X - -

Chrom atographie sur A l*Oj[7.8] - 83% 8 * Mo ( 67 h) <0,1%

V olatilisation de H2T e [9] X >90%

id. - =<10%UTSb(93h) <0,01%

L o rs q u e le te l lu r e - 1 3 2 e s t u t i l i s é c o m m e g é n é r a te u r d 'io d e - 1 3 2 , i l n e d o it p a s ê t r e n é c e s s a i r e m e n t i s o lé s a n s e n t r a în e u r n i so u s f o r m e d e h a u te s a c tiv i té s sp é c if iq u e s ; le s im p u re té s é v e n tu e lle s du te l lu r e son t to lé r a b le s dans la m e s u re où e l le s n 'a c c o m p a g n e n t p a s l 'io d e -1 3 2 dans le p ro c e s s u s de sé p a ra tio n de c e lu i-c i .

I l e s t c l a i r que l e s m é th o d e s p a r p r é c ip i ta t io n so n t lo n g u e s e t f a s t i d ie u s e s d 'a u ta n t p lu s que la m a n ip u la tio n e s t té lé c o m m a n d é e . L a m é th o d e a n g la is e (p ré c ip i ta t io n du T e) e s t p lu s s im p le d an s la m e s u re où la d éc o n ta m in a tio n du te l lu r e se fa it en p ré c ip ita n t c e lu i-c i p lu s ie u rs fo is m a is avec le m ê m e agen t r é d u c te u r a lo r s que d an s la m éth o d e a m é r ic a in e (p ré c ip i ta t io n de TeO^) p lu s ie u r s r é a c t i f s de p ré c ip ita t io n son t em p lo y és .

L a s é p a ra tio n du te l lu r e p a r c h ro m a to g ra p h ie s u r a lu m in e ne r e q u ie r t p as la p ré se n c e d 'e n t r a în e u r , la m an ipu la tion e s t s im p le , rap id e et s 'a d a p te b ien à la té léco m m an d e ; de p lu s , 1 ' a lum ine r é s i s te b ien aux e ffe ts d es r a d ia t io n s . P a r c e tte m é th o d e , on o b tie n t é g a le m en t du m o ly b d è n e -99 s a n s e n t r a în e u r , en so lu tio n a m m o n ia c a le , acco m p ag n é d ' i o d e - 131, que l 'o n p eu t a is é m e n t é l im in e r .

146 R. STIÈNNON-BOVY et G. HAEGEMAN-GELADI

c*'^^46.04h)% o •(s? h) - ¿ a

Ъ9Те(2,12-lOS a)

»"R u(stable)

[4]

L e m o ly b d è n e -99 e s t le se u l i'so tope ra d io a c t i f du m o lybdène p ra tiq u e m e n t u til isa b le ; i l peut non seu lem en t s e r v i r com m e tr a c e u r iso topique m a is au ss i com m e g é n é ra te u r de te ch n é tiu m [8 ].

L a p r é p a ra t io n du te l lu r e - 1 3 2 p a r v o la t i l i s a t io n e s t a s tu c ie u s e , e l le e s t c o m p é ti tiv e de la p r é p a ra t io n p a r c h ro m a to g ra p h ie s u r a lu m in e s i la d é c o n ta m in a tio n e s t b o n n e .

2 . 2 . R é s u l ta ts e x p é r im e n ta u x

L e s c ib le s d 'u ra n iu m (l^Og), enveloppées dans une feu ille d 'a lu m in iu m , so n t d is s o u te s à f ro id av ec de l 'a c i d e c h lo rh y d riq u e e t de l 'a c i d e n itr iq u e . L a so lu tio n ac id e e s t d iluée ju s q u 'à ce que le pH atte igne la v a le u r 1; ensu ite on l a f a i t p a s s e r s u r vrne co lo n n e d e 20 g d 'a lu m in e (W oelm n° 10137) qui a 25 m m de d ia m è t r e , l 'a l u m in e r e p o s e s u r un v e r r e f r i t t é G3; s e u ls le te l lu r e e t le m olybdène son t f ix és p a r l 'a lu m in e . La fixation du te l lu re n 'e s t p a s a ffec tée p a r la v i te s s e de p a s sa g e s u r 1 ' a lum ine , 10 % du te l lu re in it ia le m e n t p r é s e n t en so lu tio n n e so n t p a s f ix é s p a r l 'a l u m in e . L a co lo n n e e s t la v é e à 1 ' eau e t le m o lybdène e s t é lu é p a r 1 ' am m on iaque , p lu s ra p id e m e n t p a r NH4OH conc. que p a r NH4OH 2N; i l fau t 100 m l de NH^OH conc. au lie u d e 150 m l d e NH4OH 2N. P ra t iq u e m e n t , no u s é lu o n s p a r NH4OH 2N p o u r é c o n o m ise r du r é a c t i f e t p o u r r é d u ir e la te n e u r en a lu m in e d an s la so lu tion ;

F ig u e 4

Elution des molybdènes e t des tellures d'une colonne d'alum ine de 20 g.

PRÉPARATION DU TELLURE-132 ET DE L*IODE-132 147

de p lu s , s i le m olybdène do it ê t r e ré c u p é ré com m e il fau t é l im in e r l 'a m m o n ia q u e , i l y a in té r ê t à ce que s a c o n c e n tra tio n so it fa ib le . P o u r un m ê m e v o lu m e d 'é lu a n t la c o u rb e d 'é lu t io n a t te in t son m a x im u m que le m o lybdène so it avec ou s a n s e n tra în e u r ; la fin de 1 ' é lu tio n e s t cependan t m o in s ra p id e quand i l n 'y a p a s d 'è n t r a în e u r . L a f ig u re 4 m o n tre 1' é lu tio n du m olybdène s a n s e n t r a în e u r p a r une so lu tio n NH4OH 2N, l a v i t e s s e d 'é lu t io n é ta n t d e 200 m l/h . L e m o lybdène s ' é lu e en m ê m e te m p s que 1' iode, i l e s t donc to u jo u rs p ra tiq u em e n t con tam iné p a r de l 'io d e -1 3 1 . Nous avons é tud ié 1 'élu tion de t e l lu r e p a r d e s so lu tio n s d 'h y d ro x y d e sod iq u e 3, 2 e t 1N en p r é s e n c e ou non d 'e n t r a î n e u r ; lo r s q u e la c o n c e n tra t io n de 1 ' é lu a n t d im in u e , l a f in de 1 'é lu tio n e s t m o in s r a p id e . P o u r une m ê m e c o n c e n tra tio n d 'h y d ro x y d e s o d ique e t en p ré s e n c e de te l lu r e e n tra în e u r 1 ' é lu tio n s e te rm in e p lu s r a p id e m e n t. N ous é lu o n s p ra t iq u e m e n t le t e l l u r e a v e c N aO H 3N; 55 à 60% du t e l l u r e p r é s e n t so n t é lu é s e n t r e le 10e e t le 30e m l. N ous n 'a jo u to n s p a s du t e l l u r e e n t r a în e u r , c a r s a p r é s e n c e e s t g ê n a n te lo r s q u ' i l f a u t a m e n e r la so lu tio n à pH = l p o u r 1 'a d s o r b e r s u r d e s c o lo n n e s d 'a lu m in e en v u e d e la s é p a ra t io n d e 1' io d e . L a f ig u re 4 donne un e c o u rb e d 'é lu t io n du te l lu r e s a n s e n t ra în e u r p a r une so lu tio n de NaOH 3N, la v i te s s e d 'é lu t io n é ta n t de 165 m l /h . L 'a n a ly s e p a r s p e c t r o m é tr ie g am m a m o n tre q u 'i l y a 8 6 , 6 % de i32Te, 10,9% de 99Mo, 1,3% de Ш1, 0,8% de 103RU e t 0,3% de 95Zr dans le c a s le p lu s d é fav o rab le ; le s a n a ly se s son t fa ite s a p rè s 15 e t 30 jo u rs , le s r é s u l ta t s son t r a p p o r té s au m om ent de la p ré p a ra tio n * .

3. PRÉPA RA TIO N DE L ' IO D E -132

3..1. Vue d 'e n s e m b le d e s m é th o d es de p ré p a ra tio n

L e s m é th o d es de s é p a ra tio n de l 'io d e -1 3 2 du te l lu re -1 3 2 a c tu e lle m e n t connues so n t d é c r i te s au ta b le a u H.

L 'io d e -1 3 2 do it pouvo ir ê t r e obtenu sa n s e n tra în e u r . D ans c e r ta in s ca s , so n a c t iv i té sp é c if iq u e d o it ê t r e é le v é e ; e l le d ép e n d e s s e n t ie l le m e n t de l 'u s a g e auquel on le d e s tin e , p a r exem ple , l 'in je c t io n p a r vo ie in tra v e in e u se ou l e m a rq u a g e de m o lé c u le s . L 'i o d e d o it ê t r e e x e m p t d e c o n ta m in a n ts r a d io a c t i f s qu i a u r a ie n t le m ê m e c o m p o rte m e n t que 1 ' iode é tu d ié ; d a n s le c a s d es ap p lica tio n s b io log iques ou physio log iques, l ' iode do it ê t re exem pt de c o n ta m in a n ts ra d io a c t i f s qui p ro v o q u e ra ie n t d e s d o m m ag es d an s l ' o r g a n ism e . L 'io d e do it ê t r e s é p a ré du te l lu r e p a r une m a n ip u la tio n s im p le , r a p ide , e n tra în a n t t r è s peu de r is q u e s de co n tam ination .

P o u r v o la t i l i s e r l ' i o d e à p a r t i r d 'u n e s o u rc e so lid e de te l lu r e , i l fau t t r a v a i l l e r à te m p é r a tu r e é le v é e p o u r f o n d re l a s o u r c e d e t e l lu r e . C e la a p o s é un p ro b lè m e d if f ic ile p o u r le ch o ix du m a té r ia u d e c o n s tru c t io n de l 'a p p a r e i l l a g e . P o u r v o la t i l i s e r l ' i o d e à p a r t i r d 'u n e s o u rc e liq u id e de t e l lu r e , i l fa u t t r a v a i l l e r à te m p é r a tu r e m o in s é le v é e ; l a m a n ip u la tio n , b ie n que s im p le , i l s 'a g i t d 'u n e d is t i l la t io n , d em an d e à ê t r e c o n s ta m m e n t s u r v e i l lé e e t l e s r i s q u e s de co n tam in a tio n ne so n t p a s n é g lig e a b le s .

L a m é th o d e p a r p r é c ip i ta t io n c o n s ti tu e u n e a m é l io ra t io n p a r r a p p o r t à la m éth o d e p a r v o la til is a tio n , c a r e l le s e fa i t à la te m p é r a tu re o rd in a ire ;

1)1 Ces analyses ont é té faites par M onsieur J. C olard du serv ice de S pectrom étrie n u c léa ire .

148 R. STIENNON-BOVY e t G. HAEGEMAN-GELADI

TABLEAU II

M ÉTH OD ES DE SÉPA RA TIO N DE L 'IO D E -1 3 2 SANS ENTRAÎNEUR

Principe Solution de **1 Rendement chim ique Contam inant

V olatilisation de I 2 d 'une -

source solide de T e 0 2 [10] - - -

solution de Te4+ [6,11] NaOH ou NaHSOj (sol. diluées) - -

P récip itation de T e 0 2 [5] tam pon acé ta te - ш Те=»0,2%

Chrom atographie sur

A l ^ [8 , 12] NH4OH N/100 65% ш Te = 10-“%

Fe(OH)s [13] eau ou sérum physiologique - -

KPS-200 saturé Sn2+[14] eau 70 a 95% -

c e p e n d a n t u n e c e r ta in e q u a n tité d e t e l lu r e , de l 'o r d r e du m ic r o g ra m m e , r e s t e en so lu tio n e t c e tte te n e u r , b ie n q u ' e l le ne so it p a s to x iq u e , e s t g ê n a n te p a r c e q u 'e l l e c o n fè re à la so lu tio n d 'io d e un goût a l l ia c é .

L e s s é p a ra t io n s de l ' i o d e p a r c h ro m a to g ra p h ie se fon t à f ro id , le t e l lu r e e s t fixé sa n s e n tra în e u r s u r 1' éch an g eu r. P a rm i le s éch an g eu rs p ro p o s é s d an s la l i t t é r a tu r e , l 'a lu m in e e s t le m e il le u r p a r sa s ta b ili té aux r a d ia t io n s ; de p lu s , e l le p e r m e t d 'o b t e n i r 1 ' io d e d a n s un m il ie u q u i s e p r ê te n o ta m m e n t b ie n au m a rq u a g e d e s m o lé c u le s de p ro té in e s e t l a te n e u r d e s im p u re té s s ta b le s qui r isq u e n t d 'a c c o m p a g n e r l 'io d e e s t t r è s fa ib le a lo rs que l e re n d e m e n t de l 1 é lu tio n à p a r t i r de l ' h y d ro x y d e f e r r iq u e n e n o u s p a r a î t p a s s a t is f a is a n t* e t que 1 ' é c h a n g e u r d ' io n s p ro p o sé do it ê t r e s a tu ré avec un e so lu tio n de c h lo ru r e s tan n eu x .

3 . 2 . R é s u lta ts e x p é r im e n ta u x

N ous av o n s é tu d ié sp é c ia le m e n t la s é p a ra tio n de l ' i o d e p a r c h ro m a to g ra p h ie s u r a lu m in e . N ous d isp o so n s de te l lu re -1 3 2 en so lu tio n sod ique 3N o b te n u e d a n s le s c o n d itio n s d é c r i te s en 2 . 2 . C es so lu tio n s c o n tie n n e n t de l 'a l u m in e ; p o u r m a in te n ir c e l l e - c i en so lu tio n , n o u s a d s o rb o n s , à pH = 1, l e te l lu r e - 1 3 2 s u r la co lonne d 'a lu m in e qui s e r v i r a à s é p a r e r l 'io d e - 1 3 2 . L e r e n d e m e n t de la s é p a r a t io n de l ' i o d e n 'e s t p a s a f fe c té p a r la g ra n u lo - m é t r i e de 1 ' a lu m in e , n i p a r la c o n c e n tra tio n de la so lu tio n d 'a m m o n ia q u e quand c e l le -c i v a r ie e n t re N /100 e t 2N, n i p a r la v i te s s e de 1' é lu tion m êm e quand c e l le -c i a t te in t 25 m l/m in . L e p o ids de l 'a lu m in e in fluence fo rte m e n t le re n d e m e n t de la s é p a ra tio n ; a in s i, p o u r d e s p o ids de 5, 10 e t 20 g d 'a l u m in e , le re n d e m e n t e s t r e s p e c tiv e m e n t de l 'o r d r e de 80, 75 e t 50%. L 'a n a

* La méthode fait l 'o b je t d'un brevet dont nous n'avons pas pris connaissance.

PREPARATION DU TELLURE-132 ET DE L'IODE-132 149

ly se , p a r s p e c tro m é tr ie gam m a* , d es so lu tio n s d 'i o d e - 132 ob tenues ré v è le to u jo u rs la p ré se n c e d ' i o d e - 131 en q u an tité s v a r ia b le s com m e nous l 'a v o n s s ig n a lé en 1. L o rs q u e no u s em ployons d e s co lo n n es de 20 g d 'a lu m in e s u r l e s q u e l le s n o u s av o n s a d s o rb é ju s q u 1 à 5 m e de t e l lu r e - 1 3 2 , n o u s n ' av o n s ja m a is d éc e lé du i32Te en so lu tion e t dans le s c a s le s p lu s d é fa v o ra b les nous av o n s d é c e lé 2,8-10-2% d e " M o e t 10‘2% d e i03Ru; lo r s q u e no u s em p lo y o n s des co lonnes de 5 g d 1 a lum ine s u r le sq u e lle s nous avons ad so rb é ju sq u 1 à 7,5 m e de te l lu r e -1 3 2 , l e s te n e u r s en i 32T e e t en 1(>3Ru so n t in f é r ie u r e s à 10_2% et c e lle en $Шо e s t de l 'o r d r e de 5-10-2%. La f ig u re 5 donne le s cou rbes d 'é lu tio n d e s io d e s p a r NH4OH N /100 de co lonnes de 5 e t de 20 g d 'a lu m in e ; e lle m o n tre que p o u r une co lonne de 5 g d 'a lu m in e 50% de l ' i o d e son t re c u e i l l is d a n s l e s 8 p r e m i e r s m i l l i l i t r e s , l a v i t e s s e d 'é lu t io n é ta n t de 5 m l /m in , ta n d is que p o u r u n e co lo n n e d e 20 g d 'a lu m in e e n v iro n 50% de 1' io d e so n t r e c u e i l l i s e n t re le 4 e e t le 2 0 e m l, la v i te s s e d 'é lu t io n é ta n t de 1 m l/m in .

ml NHjOH N/100 ml МН<0Н N /100

Figure 5

Elution par NHjOH N/100 des iodes d'une colonne d'alum ine de différents poids.

P ra t iq u e m e n t , n o u s ad o p to n s d e s c o lo n n e s d e 5 g d 'a lu m in e W oelm n° 10137, de 2,5 cm d e d ia m è t r e , r e p o s a n t s u r un v e r r e f r i t t é G2 ou G3; l a te n e u r en a lu m in iu m d e l a s o lu tio n d ' i o d e - 132 e s t é g a le ou in f é r i e u r e à 1 0 y /m l .

4 . É T A T S DE V A LE N C E D ES SOLUTIONS. DE T E L L U R E -1 3 2 E T D 'I O D E - 132

P a r c h ro m a to g ra p h ie s u r p a p ie r , n o u s a v o n s r e c h e r c h é l e s é t a t s d e v a le n c e du te l lu r e - 1 3 2 e t de l 'io d e - 1 3 2 l o r s q u ' i l s so n t é lu é s de l 'a l u m in e r e s p e c t iv e m e n t p a r NaOH 2N e t NH4OH N /1 0 0 .

4 . 1. S o lu tion d e te l lu r e - 1 3 2 d a n s NaOH 2N

P o u r a n a ly s e r un e so lu tio n b a s iq u e de te l lu r e , nous avons m o n tré qu 1 i l fa u t l a d i lu e r ou la n e u t r a l i s e r e t que la p r é s e n c e d 'e n t r a î n e u r s n ' e s t p a s

* Ces analyses on é té faites par M onsieu r). C olard du serv ice de S pectrom étrie n u c léa ire .

TABLEAU III

A NALYSE* DE SOLUTIONS SANS EN TRA ÎN EU RS DE 132Te DANS NaOH 2N


SolvantRf Composition de la solution

Te IV5»

6°)Te IV Te VI

Acétone 90%, H£> 5%, HC1 conc. 5% [16] 0,61 0 87,2± 1,7

M éthanol lUrfo, eau 25Ща [15] 0 0,72 9 2 ,2 * 0 ,5

* Type du papier: Carl Schleicher & Schüll 2040a.

M ilieu à analyser: solution am enée jusqu’ à p H = l avec HNOs.

Mode de dé tection : radioactivité".

** Valeur moyenne de cinq analyses.

TABLEAU IV

A N A LY SE- DE SOLUTIONS D 'IO D E -1 3 2 SANS ENTRAÎNEURS DANS NH4OH N /100

Solvant RfComposition de la solution

(%)**

I" IO ; KT4 I- i o ; + io4-

Ethanol, HjO, NH4OH 14N (30:10:5)[18] 0,7 0 ,3 1 -0 ,3 7 0 98,6 ±2,0 1 ,4±2,0

M éthanol 100% [19] 0,69 - 0 98,7 ±1,8 1 .3 * 1 ,8

M éthanol 75% [20] 0,76 0,45 - 98,7 ±2,5 1,3±2,5

* Type du papier : C arl Schleicher & Schüll 2040a.

M ilieu â analyser: NH4OH N /100.

Mode de détection : rad ioac tiv ité .

** Valeur moyenne d 'au moins cinq analyses.

r e q u is e [15]. L e s r é s u l t a t s d 'a n a ly s e d o n n és au ta b le a u III m o n tr e n t que 90% du t e l l u r e s e t r o u v e n t à l 1 é ta t q u a d r iv a le n t .

4 . 2 . S o lu tio n d 'io d e - 1 3 2 d a n s NH4OH N /1 0 0

P o u r a n a ly s e r une so lu tio n d 'io d e , nous avons le choix e n tre p lu s ie u r s s o lv a n ts p o u r l a c h ro m a to g ra p h ie s u r p a p ie r [17]. N ous av o n s u t i l i s é c e r ta in s d 'e n t r e eux p o u r a n a ly se r une m êm e so lu tion d 'io d e - 132; le s r é s u lta ts d 'a n a ly s e so n t p o r té s au ta b le a u IV.

P o u r l e s a p p lic a tio n s m é d ic a le s , l e s p h a rm a c o p é e s a n g la is e e t a m é r i c a in e im p o s e n t que l a te n e u r en io d u re s o i t s u p é r ie u r e à 95% d a n s le c a s d e s s o lu tio n s d ' i o d e - 131 [21, 22]; p a r a n a lo g ie , l e s s o lu tio n s d 'io d e - 1 3 2


do iven t s a t i s f a i r e à la m ê m e condition . L e s r é s u l t a ts ind iqués au ta b le a u IV m o n tre n t que c e tte co n d itio n e s t e f fe c tiv e m e n t r é a l i s é e lo r s q u e l 'io d e -1 3 2 e s t s é p a ré du te llu re -1 3 2 p a r ch ro m a to g rap h ie s u r a lum ine avec une so lu tion d e NH4OH N /1 0 0 . P o u r d e c o n t rô le s r o u t in i e r s p a r c h r o m a to g r a p h ie s u r p a p ie r , nous rec o m m an d o n s d ’u t i l i s e r com m e so lvan t la so lu tion de m é th a - nol à 100% p lu tô t que la so lu tio n à 75% re c o m m a n d é e p a r le s p h a rm a c o p é e s p r é c i t é e s , c a r l a d if fé re n c e e n t r e l e s Rf d e s io d u r e s e t io d a te - p e r io d a te e s t p lu s n e tte e t la so lu tion e lle -m ê m e e s t p lu s fa c ile à p r é p a re r ; i l convient a u s s i de r é d u ir e à 2 h la d u ré e de d év e lo p p em en t du c h ro m a to g ra m m e afin de la r e n d r e co m p a tib le av ec la p é r io d e de l 'io d e -1 3 2 [19].

5. STA B IL ITÉ DES SOLUTIONS DE T E L L U R E -1 3 2 E T D 'IO D E -132 SANS ENTRAÎNEURS

Il e s t b ie n connu que c e r ta in s ra d io é lé m e n ts en so lu tio n s t r è s d ilu é e s ont un c o m p o rtem e n t co llo ïd a l; c e s so lu tio n s con tiennen t a lo r s des sy s tè m e s p o ly d is p e r s é s en é ta t d 1 év o lu tio n p lu s ou m o in s le n te . L e s ra d io c o llo ïd e s ont, e n tre a u tre s , la p ro p r ié té de s 'a d s o r b e r s u r le s su rfa c e s des ré c ip ie n ts qui le s con tiennen t. R appelons q u 'à 1 c de te llu re -1 3 2 sa n s e n tra în e u r c o r re s p o n d un p o id s de 3 ,2 -10"6 g e t q u 'à 1 c d ' i o d e - 132 sa n s e n t r a în e u r c o r re s p o n d un p o id s de 10-7g.

5. 1. S o lu tion de te l lu r e - 1 3 2

Il n ' e s t p a s exc lu à p r io r i que le s so lu tio n s de te l lu r e in fin im en t d ilu ées a ie n t u n c o m p o r te m e n t r a d io c o l lo ïd a l p u isq u e l a s o lu b i l i té d e l 'o x y d e d e t e l l u r e IV , Т еО г, e s t f a ib le (0 ,67 m g d a n s 100 m l d ' e a u f ro id e ) e t q u ' en m il ie u a c id e , l 'a c i d e te l lu r iq u e Н гТ е0 4 a te n d a n c e à s e p o ly m é r is e r [23].I l n o u s e s t u t i le d 'e x a m in e r l a s ta b i l i t é d e s so lu t io n s d e t e l l u r e s a n s e n t r a î n e u r ta n t en m il ie u a c id e que b a s iq u e .

D 'u n e m ê m e so lu tio n , s a n s e n t r a în e u r , de t e l l u r e IV ou d e t e l l u r e VI r a d io a c t i f p u r , on p r é lè v e d a n s l e te m p s d e s a l iq u o te s .d o n t on m e s u r e l a ra d io a c tiv ité au m o in s 15 h a p r è s le p ré lè v e m e n t afin que le te l lu re e t l 'io d e so ie n t en é q u ilib re ra d io a c tif ; p o u r un m ê m e é ta t de v a len c e , la c o n c e n tra tio n en io n s é t r a n g e r s e s t m a in ten u e c o n s tan te . N ous em ployons d es flacons du ty p e « p é n ic i l l in e » e t d e s p ip e t te s en v e r r e r i e c o u ra n te de l a b o r a to i r e . A p rè s 120 h d 'o b s e r v a t io n p o u r le te l lu r e IV d an s la so lu tio n ay an t la co m p o s itio n su ivan te ;

HCl ; 0,06N; 0, IN; 3N,HNO3 : 0,1N; 3N,NaOH ; 0,01N; 0,1N; 2N

e t 380 h d 'o b s e r v a t io n p o u r le te l lu r e VI p ré s e n t dans la so lu tio n de com position ;

H Cl ; 0 ,1 3N; 3,4N,HNO3 : 0 ,1 8N; 4 ,1N ,NaOH ; 0, IN; 2N,

on co n s ta te que le s a c tiv i té s c o r r ig é e s p o u r la d é c ro is sa n c e rad io a c tiv e sont é g a le s .


L e s s o lu tio n s de t e l l u r e IV e t de t e l lu r e VI, ta n t b a s iq u e s q u 'a c id e s , r e s te n t donc hom ogènes; e l le s peuvent e t r e p ra tiq u em e n t c o n s id é ré e s com m e s ta b le s .

5 . 2. Solution d 1 io d e - 132

SC H W E ITZ E R e t JACKSON ont m o n tr é d e s r é s u l t a t s de f i l t r a t io n e t de ce n tr ifu g a tio n de so lu tio n s d 'io d e sa n s e n tra în e u r dont le pH e s t co m p ris e n t re 1 e t 12 p e rm e tta n t de co n c lu re que le s so lu tions sont h é té ro g èn e s [24].I l im p o rte de s a v o ir s i le s so lu tions d 'io d e -1 3 2 dont le pH e s t co m p ris en tre 7 e t 8 , é v e n tu e lle m en t s té r i l i s é e s ou re n d u e s iso to n iq u es avec le sang, son t hom ogènes.

D ' une m ê m e so lu tio n sa n s e n tra în e u r d 1 io d e - 132 am en é e à pH = 7,3 on p ré lè v e dans le te m p s (pendant 1 h) d es a liq u o te s dont on m e su re im m éd ia te m e n t la r a d io a c tiv ité . L es a c tiv i té s , c o r r ig é e s p o u r la d é c ro is s a n c e r a d io ac tiv e , é tan t é g a le s , on en dédu it que la so lu tion e s t hom ogène.

P o u r v o ir l ' e f f e t de la s té r i l i s a t io n s u r l 'h o m o g é n é i té d ' u n e so lu tio n d 'io d e -1 3 2 , nous avons co m p a ré le s a c tiv i té s d 'é c h a n ti l lo n s p ré le v é s avant e t a p r è s la s té r i l is a t io n ; c o r r ig é e s p o u r la d é c ro is s a n c e ra d io a c tiv e , e l le s so n t id e n tiq u e s . D es e s s a is se m b la b le s ont é té fa i ts avec d es so lu tio n s r e n d u es iso to n iq u e s av ec le sang ; no u s c o n s ta to n s que la p r é s e n c e de s e l s ne m o d if ie p a s la s ta b i l i té de c e s so lu tio n s .

N ous em ployons d es f la c o n s du type « p é n ic il lin e » , p r é t r a i té s * ou non, ou en p o ly é th y lè n e , e t d e s p ip e t te s en v e r r e r i e c o u ra n te d e l a b o r a to i r e ; c e l l e s - c i so n t p r é t r a i t é e s lo r s q u e nous u ti l is o n s d es fla c o n s en v e r r e p r é t r a i t é s .

L e s so lu tio n s d 'io d e -1 3 2 sa n s e n t ra în e u r dont le pH e s t c o m p ris e n tre7 e t 8 so n t s ta b le s m ê m e a p r è s s té r i l is a t io n e t a p rè s av o ir é té re n d u e s i s o to n iq u es avec le sang .

6 . ÉTALONNAGE DES ACTIVITÉS DE T E L L U R E -132 ET D 'IO D E-132

L e s m e s u r e s a b s o lu e s d e s s o lu tio n s de te l lu r e - 1 3 2 (so lu tio n d ' a c i d e n itr iq u e N /10) e t d 'io d e -1 3 2 (so lu tion n eu tre ) son t fa ite s à l 'a i d e d ' u n com pte u r 4 5rj3 de fa b r ic a tio n T ra c e rla b * * .

N ous av o n s d é te r m in é le re n d e m e n t d ' u n c r i s t a l de N al a c tiv é au T l, de f a b r ic a t io n H a rsh a w de ty p e F n° 7F8; p o u r le s so lu tio n s d 'io d e - 1 3 2 il e s t de 65,1% . C e re n d e m e n t a é té m e s u r é p en d an t p lu s de deux a n s e t n ' a p a s v a r ié de p lu s de 3,9%.

N ous m e s u ro n s l 'a c t i v i t é du te l lu re -1 3 2 fix ée s u r l 'a lu m in e en in t r o d u is a n t l a co lo n n e e l le - m ê m e d a n s un é l e c t r o m è t r e de c o n s tru c t io n CEN

* Pour p ré tra ite r le verre, c ’est-à -d ire pour le saturer avec de l'iode non radioactif, nous le traitons avec la solution recom m andée par la pharm acopée am éricaine pour le conditionnem ent des solutions d 'iode-131[21] . C ette solution contient approxim ativem ent 0,80% d ’hydroxide de sodium, 0,40% de bisulfite sodique e t 0,25% d’iodure sodique; les récipients sont ensuite lavés avec de l*eau d istillée , jusqu’à réaction neutre au tournesol.

** Les mesures absolues ont é té faites par G. G ierts, F. Leroy et J. Colard du service des Mesures nucléaires.

PRÉPARATION DU TELLURE-132 ET DE L’IODE-132 153

e t n o u s m e s u ro n s é g a le m e n t a v e c c e t é l e c t r o m è t r e 1 ' a c t iv i té to ta le de l 'io d e -1 3 2 r e c u e i l l i l o r s d 1 u n e é lu tio n , ce qui no u s p e rm e t de d é d u ire r a p id e m e n t e t a v e c p r é c is io n le r e n d e m e n t de la s é p a r a t io n de l ' i o d e - 1 3 2 .

7. SCHÉMA D ' U N E-CELLU LE DE PRODUCTION DE TEL LU R E-132 (fig. 6 )

L e c o n ta in e r co n ten a n t le p o r te - é c h a n t i l lo n i r r a d i é e s t in tro d u it d an s l a c e llu le p a r un c h a r io t- p o r te ; p o u r ê t r e o u v e r t, le p o r te -é c h a n ti l lo n e s t in tro d u it p a r un bouchon ® dans une bo îte © où se tro u v e une sectionneuse (з); l a c ib le d 'u r a n iu m e s t in tro d u ite d a n s un tu b e d e t r a n s f e r t ( i) qu i l 'a m è n e d an s une b o îte © o ù e l le to m b e d an s un p a n ie r en té f lo n © q u e l ' o n in tro d u it d ans le d is s o lv e u r © en le su sp en d an t au bouchon de c e lu i-c i ; la d isso lu tio n d e l a c ib le l a i s s e in ta c t le p a n ie r en té f lo n qu i p eu t s e r v i r à nouveau p o u r un t r a n s f e r t . Deux a b s o r b e u r s © contenant une so lu tion de soude sont p rév u s pou r r e te n i r év en tu e llem en t l ' io d e l ib re qui s 'é c h a p p e ra i t lo r s de la d isso lu t io n de l 'u r a n iu m . L a so lu tio n d 'u r a n iu m .et d e s p ro d u its de f is s io n p a s s e s u r u n e co lo n n e c o n ten a n t de l 'a l u m i n e ® ; la p a r t i e m é d ia n e de c e tte co lonne qui c o n tie n t l 'a l u m in e e s t a is é m e n t r e m p la ç a b le . S eu ls l e t e l lu r e e t le m o ly b d è n e so n t f ix é s p a r l 'a l u m in e , la so lu tio n c o n ten a n t l 'u r a n iu m e t le s a u t re s p ro d u its de f is s io n e s t é c a r té e . Le m olybdène e s t é lué et é c a r t é com m e ré s id u ou év en tu e llem en t c o n se rv é pou r ê t r e ré c u p é ré . Le te l lu re e s t e n s u ite é lu é e t la so lu tio n e s t t r a n s f é r é e d an s le r é c ip ie n t® où e lle e s t a m e n é e à pH vou lu p o u r ê t r e d is t r ib u é e p a r l ' i n t e r m é d i a i r e d ' u n e p ip e tte au to m atiq u e © d an s d e s b o u te ille s ou a d s o rb é e s u r d es co lo n n es d 'a lu m in e .

Figue 6

Schéma d'une cellule de production de tellure-132.


C olonnes e t b o u te ille s d éfilen t sous la b u re tte g ra c e à un p la teau to u r n a n t© , e l le s so n t b o u c h é e s e t s o r t ie s , é v e n tu e lle m e n t d an s un c o n ta in e r , h o r s de l a c e llu le p a r un c h a r io t - p o r te .

L e s m a n ip u la tio n s qui p o u r ra ie n t e n t r a în e r une co n ta m in a tio n de p lu to n iu m s e fon t d an s d e s b o îte s © e t © e n a c ie r inoxydab le avec d e s v o y an ts en P le x ig la s . C es b o îte s so n t en d é p re s s io n p a r ra p p o r t à l ' i n t é r i e u r de la ce llu le qui e s t e l le -m ê m e en d é p re s s io n p a r ra p p o r t au lo c a l où se tro u v e la c e llu le .

L e s a l im e n ta t io n s en r é a c t i f s so n t p la c é e s à l 'e x t é r i e u r de la c e llu le . L e s liq u id e s so n t t r a n s f é r é s p a r p r e s s io n d a n s l e s d if fé r e n te s p a r t i e s de l 'a p p a r e i l l a g e .

O n d is t in g u e t r o i s é v a c u a tio n s de r é s id u s ; c e l le d e s r é s id u s s o l id e s (p o r te -é c h a n ti l lo n s ) , c e lle d e s r é s id u s fo r te m e n t a c t i f s I (so lu tio n s d ' u r a nium e t des p ro d u its de fiss io n ), ce lle des ré s id u s fa ib lem ent a c tifs II (au tres so lu tions).

P o u r ce tte ce llu le , nous p révoyons com m e p ro tec tio n co n tre le ray o n n em e n t un é c r a n de p lom b é p a is de 1 0 cm p o u r l e s f a c e s l a t é r a l e s e t le fond e t d e 3 cm p o u r le to i t . N ous p o u r ro n s a u s s i m a n ip u le r 5 c de p ro d u its de f is s io n , ce qui no u s p e r m e t t r a d ' i s o l e r 500 m e de te l lu r e - 1 3 2 à p a r t i r de 250 g d 'u r a n iu m i r r a d i é p en d an t t r o i s jo u r s d an s un flux th e rm iq u e de 5 . l 0 11n/cm 2 .s e t d é s a c tiv é p en d an t deux jo u rs ; 100 ¡xg de p lu to n iu m -2 3 9 se s e ro n t a lo r s fo rm é s .

8 . PRO TECTIO N BIOLOGIQUE POUR LE TRANSPORT ET L ' UTILISATION DE COLONNES DE CHROMATOGRAPHIE

L a p r o te c t io n b io lo g iq u e que no u s p ré s e n to n s (fig . 7 e t 8 ) se co m p o se de q u a t r e p a r t i e s ; le c o u v e rc le A, le c o rp s B d a n s le q u e l s e p la c e la c o lonne de ch ro m a to g rap h ie , le t i r o i r C dans lequel se loge le flacon ré c e p te u r d es tin é à re c e v o ir 1' é luan t, e t la b ase D.

P o u r p e r m e t t r e 1' in tro d u c tio n d ' u n vo lum e donné d ’ é lu an t dans la c o lo n n e , le c o u v e rc le A s e d é p la c e a is é m e n t d a n s un p la n h o r iz o n ta l g r â c e à un p iv o t© fix é d a n s le c o rp s B . L e c o u v e rc le A e s t m u n i d ' u n bouchon en P le x ig la s © dont le d é p la c e m e n t e s t l im ité p a r une la m e de r e s s o r t , ce bouchon se p la c e s u r la c o lo n n e © e t la m a in tie n t en p la c e pendan t le t r a n s p o r t . L a co lonne de c h ro m a to g ra p h ie e s t en v e r r e , 1 'é c h a n g e u r © re p o s e s u r une p laque en v e r r e f r i t t é © ; e lle e s t g a rn ie p a r m oulage de ré s in e synth é t iq u e ® , de 1 ' a r a ld i te p a r ex e m p le , d an s le double b u t de la p r é s e r v e r d e s ch o c s p en d an t le t r a n s f e r t e t de r e n d r e m o in s s é v è r e s le s c r i t è r e s de fa b r ic a tio n . D ans la p a r t ie C, une ca v ité e s t m énagée pou r y lo g e r un flacon du ty p e « fla c o n à p é n ic i l l in e » © d ans le q u e l 1 'é luan t e s t r e c u e il l i . Le flacon e s t m ain tenu en p la c e p a r t r o i s r e s s o r t s © ; la p a r tie m obile, e lle se déplace a is é m e n t dans un p lan h o r iz o n ta l g râ c e à un p ivo t en B e t D ® . La p a r t ie D c o n s titu e la b a se fixe de la p ro tec tio n , e lle e s t s o lid a ire de la p a r tie B g râc e à t r o i s v is P o u r le t r a n s p o r t , un v e r r o u i l la g e © m a in t i e n t l e s p a r t i e s A, B e t C s o l id a i r e s .

L a p ro te c tio n , te l le q u 'e l l e e s t d e s s in é e (é c h e lle 1 /2 ) ,e s t p ré v u e p o u r ê t r e fa ite en p lom b e t p o u r c o n ten ir une colonne d 'a lu m in e ch a rg ée de 10 m e de te llu re -1 3 2 . Le f laco n r é c e p te u r e s t un flacon de 50 m l.

PRÉPARATION DU TELLURE-132 ET DE L’ IODE-132 155

Figure 7

Protection biologique pour une colonne de chromatographie.

Figure 8

Vue de la protection biologique pour une colonne de chromatographie.


L e d is p o s i t i f que n o u s p ro p o s o n s a s s u r e donc u n e p ro te c t io n c o n t r e le ray o n n em en t pendant le t r a n s p o r t du rad io é lém en t du c e n tre de production au l ie u d 'u t i l i s a t i o n , p en d a n t l 'u t i l i s a t i o n du r a d io é lé m e n t au la b o r a to i r e e t p e n d a n t l e s to c k a g e e t l e s o p é ra tio n s d e p ré lè v e m e n t de so n p ro d u it de f il ia tio n . Ce d is p o s itif e s t ad a p ta b le à to u te s le s s é p a ra tio n s c h ro m a to g ra - p h i que s de r a d io é lé m e n ts .

9. MARQUAGE DE M O LÉCU LES DE PR O TÉIN ES A L 'IO D E -132

9 . 1 . E ta t d e s c o n n a is sa n c e s [25]

L e m a rq u a g e d e s -m o lé c u le s de p ro té in e s à l ' i o d e p o se le p ro b lè m e du m arq u ag e p ro p re m e n t d it e t ce lu i de la sé p a ra tio n de l 'io d e l ib re Ii de l 'io d e l i é à l a p ro té in e Ip. C e s o p é ra tio n s d o iv e n t ê t r e m e n é e s d 'a u ta n t p lu s r a p id e m e n t que l a p é r io d e r a d io a c tiv e de l ' i s o to p e c o n s id é ré e s t c o u r te . Le m a rq u a g e e s t une o p é ra tio n ra p id e : de l ' i o d e so u s fo rm e m o lé c u la ir e e s t a g ité av ec un e so lu tio n de p ro té in e d an s d e s c o n d itio n s de pH d é te rm in é e s . P a r é c h a n g e d 'i o n s , Ia e t Ip p e u v e n t ê t r e s é p a r é s r a p id e m e n t ; I ie s t f ix é d a n s c e r ta in e s c o n d itio n s p a r un e r é s in e an io n iq u e a lo r s que 1 1 Ip ne 1 ' e s t p a s . L e r e n d e m e n t g lo b a l d e l a m a n ip u la tio n p e u t a t te in d r e ju s q u ' à 30%.

9 . 2 . R é s u l ta ts e x p é r im e n ta u x

Nous avons m a rq u é de la sé ru m -a lb u m in e hum aine avec 20 à 25% de re n d e m e n t. N ous a v o n s v érifié^ q u ' a p r è s p a s s a g e s u r la r é s in e an io n iq u e to u t l ' iode l ib r e e s t é lim in é de la so lu tion de p ro té in e ; p o u r ce f a i r e nous avons a n a ly s é c e tte so lu tio n p a r c h ro m a to g ra p h ie s u r p a p ie r en u t i l i s a n t co m m e so lv a n t une so lu tio n de m é th an o l à 75%; la p ro té in e ne m ig re p a s a lo r s que l ' i o d e l ib r e a un Rf de 0,75 [20].

E n p re n a n t d es p ré c a u tio n s c la s s iq u e s , nous avons obtenu d es so lu tions s té r i le s e t ap y ro g èn eâ de p ro té in e s m a rq u é e s à l ' i o d e - 132.


[1] STIÉNNON-BOVY, R .. L 'iode-132, BLG44(1960).[21 STIÉNNON-BOVY,R., Bibliographie: Iode-132 (1939-1961) 116 références, BLG/B-2(1962).[3] STIÉNNON-BOVY, R .etGELADI, G., r=<Nomogrammes pour déterm iner l 'a c tiv ité du te llu re-132 né

cessaire pour obtenir une ac tiv ité donnée en io d e -132 » , N uclear M ed. 2 (1961) 61.JÍ4] BLOMEKE, J. O. and TODD, M. F . , Uranium- 235 Fission- product as a Function of therm al Neutron Flux,

irradiation Tim e, and a decay Tim e. I. Atomic Concentrations and gross Totals, ORÑL-2127 (1957).[5] STANG, L. G. J r ., TUCKER, W .D. . BANKS, H .O .Jr /, DOERING, R. F. and MILLS, Т .Н ., "Production

of iod ine-132", Nucleonics 12 , 8(1954) 22.[6] COOK, G .В ., EAKINS, J. and VEALL, N. "The Production and c lin ica l Applications of I132", Intern.

J. Appl. Radiation and Isotopes 1 (1956) 85.[7] Progress Report, N uclear Engineering D epartm ent, BNL 506 (Jan. 1-M arch 31,1958).[8] RICHARDS, P . , "A Survey of the Production of the Brookhaven N ational Laboratory of Radioisotopes

for m ed ical R esearch", Rass. in tern , e le ttron ica e n u c le a te , Rome 5(1960) 223.[9] EAKINS, J .D . , ROBSON, J. and STOCKLEY, H .F ., "A new production Process for te llu riu m -132",

III tern . J. Appl. Radiation and Isotopes 9 (1960) 124.l i o ] WINSCHE, W .E ., STANG, L .G . Jr. and TUCKER, W .D ., "Production of iod ine-132", Nucleonics 8,

3(1951) 14. . . . . . . . .


[11] ARNOTT, D .G . and PERUMA, C. P . , "An em anating Source for l132" , Intem . J. Appl. Radiation and Isotopes 2 (1957) 85.

[12] STANG, L.G. J r ., TUCKER, W .D ., DOERING, R. F . , WEISS, A .J . , GREENE. M.W. and BANKS, H.O., D evelopm ent of M ethods for the Production of certa in short-lived Radioisotopes, Proc. In tem . Conf. Radioisotopes Sci. Research, Paris (Sept. 9 - 20, 1957) 1 (1958) 50.

[13] Verfahren zur Gewinnung von trâgerfreiem 132-Jod in steriler Form aus 132- T ellu r fiir m edizin ische Zw ecke, Germ an Patent DAS 1, 045, 596 (D ec. 4 , 1958).

[14] MÜNZE, R . , "Ein neues Verfahren zur kontinuierlichen Herstellung von trâgerfreiem 1S2I aus ш Т е" , K em energie 3 (1960) 518.

[15] STIÉNNON-BOVY, R. e t HAEGEMAN-GELADI, ,G . , Séparation du te llu re -IV e t du te llure-V I par chro- m atographie sur papier (à paraître).

[16] GHOSH MAZUMBAR, A. S. and LEDERER, M . , "The Separation of c a r r ie r-free te llu rium Tracers by paper C hrom atography", J. inorg. N uclear C hem . 3 (1958) 379.

[17] HAEGEMAN-GELADI, G . , Paper chrom atography. Rf values o f th e several states o f iod ine , BLG/B (à paraître).

[18] LEDERER, E. and LEDERER, M . , C hrom atography. A review o f principles and applications, Elsevier Publishing Com pany (1954) 339 pp.

[19] STIÉNNON-BOVY, R. e t GELADI, G . , Analyse des formes sous lesquelles l ’iode-132 apparaît lorsqu’il est séparé du te llure-132 par chrom atographie sur alum ine, BLG 55 (1960).

[20] PINAJIAN, J .J . and CHRISTIAN, J .E . , "The D eterm ination o f Iodide-iodate Activity in Sodium Radioiodide (I131) by au tom atic Scanning o f paper C hrom atogram s", J. Am. pharm . Assoc. (S ci. Ed.) 44 (1955) 107.

[21] Sodium rad io -iod ide ( IU1) solution, British Pharm acopoeia (1958) 608.[22] Sodium rad io -io d id e solution, The P harm acopoeia o f th e U nited States o f A m erica (1960) 684.[23] ANTIKAINEN, P .J ., "The ionization and autocomplex formation o f telluric acid” , Suomen Kemistilehti

28 В (1955) 135.[24] SCHWEITZER, G .K . and JACKSON, W .M . ."Low concentration chem istry. VII. Investigations on the

role of adsorption in radiocolloid form ation", J. Am. Soc. Chem . 76 (1954) 941.[25] VEALL, N. and VETTER, H . , Radioisotopes techniques and c lin ical research and diagnosis, Butterworths

(1958) 168.

D I S C U S S I O N

M. DOUIS: T he le ad p ro te c tiv e pack ag e w hich you u se fo r the a lum inaco lu m n m u s t b e v e r y c o s tly . Do you r e g a r d i t a s e x p e n d a b le o r d o e s th e u s e r h av e to r e tu r n i t?

G. HAEGEM AN-GELADI: F o r th e tim e being we only have a p ro to ty p ew hich is in o u r la b o ra to ry . It is in tended as p ro te c tio n during tr a n s p o r t and d u rin g la b o ra to ry u s e . We do not r e g a rd it a s expendable; on th e c o n tra ry , i t w ill be so ld to any c u s to m e r who w ants it .

PRODUCCIÓN DE YODO-132 A PARTIR DE TETRAFLUORURO DE URANIO IRRADIADO

M. BARRACHINA GOMEZ SECCIÓN DE RADIOQUÍMICA, DIRECCION DE QUIMICA E ISÓTOPOS DE LA

JUNTA DE ENERGIA NUCLEAR, MADRID, ESPAÑA


PRODUCTION OF IODINE-132 FROM IRRADIATED URANIUM TETRAFLUORIDE. Instead of the m eta llic uranium or uranium oxides usually used, the authors selected UF4 as the m ateria l to be irradiated.

The reasons for this choice are as follows: (a) i t possesses good therm al and radiolytic stab ility ; (b) it is easily soluble in a solution consisting of concentrated hydrochloric acid and boric acid ; (c) the dissolution reaction is gentle and without gas release; (d) the uranium is dissolved as U4+ in a non-oxidizing m edium, which permits of selective reduction of the telluric acid added as carrier.

The above factors greatly facilitate the process of separating the T e 132.The m ethod of separating the T e 13* is as follows: (a) dissolution of the UF4 in the m edium m entioned

above; (b) d irec t reduction of the te llu ric acid using SnCl2 followed by filtration; (c) re-dissolution of the Te using concentrated hydrochloric acid and hydrogen peroxide; (d) re -p rec ip ita tion of the Te in a hydrochloric m edium using SnCl2 or SO2 , followed by filtration; (e) final dissolution of the Te in concentrated n itric acid.

The n itric solution of tellurium , containing no fission products that are not isotopic with Te1*2 , is fixed on an alum ina colum n and the I 132 is removed periodically. The fixation of Te182 and the elution of I 132 were studied and the chem ical and radiochem ical purity of the product obtained was verified.

This method can be used with relatively large quantities of UF4 , which compensates for the poor integral fluxes availab le in research reactors, such as JEN - 1, and thus enables sufficient quantities of 1ш - of the order of 0. 5 с - to be obtained in establishments lacking high-flux reactors in almost continuous operation or unable to irradiate enriched uranium.

PRODUCTION D'IODE - 132 A PARTIR DE TETRAFLUORURE D4JRANIUM IRRADIÉ. On a choisi com m e m atière â irradier F4U au lieu de l'u ran ium -m éta l ou des oxydes d 'uranium hab ituellem ent utilisés.

Les raisons qui ont conduit au choix de F4U sont les suivantes: a) le tétrafluorure d'uranium a une bonne stab ilité therm ique e t radiolytique; b) i l est facilem ent soluble dans une solution d 'a c id e chlorhydrique con- contré e t d 'a c id e borique; c) la réaction de dissolution est douce e t ne dégage pas de gaz; d) l'uranium reste dissous sous forme d ’U‘*"r , dans un m ilieu non-oxydant, ce qui perm et une réduction sélective de l ’acide tellurique a jouté com m e entraîneur.

Toutes ces caractéristiques sim plifient considérablem ent le processus de séparation de 132T e . La séparation de 132 x e comprend les opérations suivantes: a) dissolution de F4U dans le m ilieu indiqué plus haut; b) réduction d irec te de l ’acide tellurique avec C ^ S n e t filtration; c) redissolution de Te au moyen d 'a c id e chlorhydrique e t d 'eau oxygénée; d) reprécip itation de Te en m ilieu chloryhdrique avec C ^S n o u S O î e t f i ltra tion; e) dissolution fina le de T e dans de l 'a c id e nitrique concentré.

La solution nitrique de te llu re , ne contenant aucun produit de fission non-isotope de i32T e, se fixe sur une colonne d 'a lum ine d 'où l 'o n ex tra it périodiquem ent I. On a ainsi é tudié les conditions de fixation du *42.Te e t d 'é lu tion de 1321, puis on a vérifié la pureté chim ique e t radiochim ique du produit obtenu.

C ette m éthode peut s 'appliquer â des quantités re la tivem ent im portantes de F4U, ce qui com pense la faible intensité des flux intégraux obtenus dans des réacteurs de recherche com m e JEN** 1 e t perm et, par conséquent, aux institutions qui ne possèdent pas de réacteur â neutrons rapides en régim e presque continu ou qui n 'on t pas la possibilité d 'irrad ie r de l'u ranium enrichi, d 'ob ten ir des quantités suffisantes de 1321 de l'ordre de 0 ,5 c.

ПРОИЗВОДСТВО ЙОДА-132, ИСХОДЯ ИЗ ОБЛУЧЕННОГО ЧЕТЫРЕХФТОРИСТОГО УРАНА. В качестве материала для облучения, вместо металлического урана или окиси урана, используемых другими экспериментаторами, был выбран F4U.

В пользу выбора F*U говорили следующие соображения: а) хорошая термическая и радиолитическая устойчивость; б) хорошая растворимость в едком растворе, состоящем из концентрированной хлористо

159

160 M. BARRACHINA ¿ÓMEZ

водородной и борной кислот; в) реакция растворения протекает не бурно и без выделения газов; г) Уран в растворе получается в виде U4+ в неокисляющей среде, что дает возможность селективного восстановления теллуровой кислоты, добавленной в качестве носителя.

Все это ведет к значительному упрощению процесса отделения Те132.Метод отделенияТе*32 состоит в следующем: а)растворение F4U в упомянутой выше среде; б) не

посредственное восстановление теллуровой кислоты при помощи Cl2Sn и фильтрация; в) вторичное растворение Те при помощи концентрированной хлористоводородной кислоты и перекиси водорода; г) осаждение Те в хлористоводородной среде с добавлением Cl2Sn или S02 и Фильтрация; д) окончательное растворение Те в концентрированной азотной кислоте.

Азотный раствор теллура, лишенный продуктов деления, не являющихся изотопами Те192, за* крепляется ка глиноземе колонны, и из нее периодически извлекается J132. В этом направлении были изучены условия фиксирования Те132 и элюирования J132, и проверялась химическая и радиохимическая чистота получаемого продукта.

Этот метод может применяться к относительно большим количествам F4U, что компенсирует слабую интенсивность интегральных потоков, которые получаются в исследовательских реакторах такого типа, как реактор JEN-1, и тем самым делает возможным получение достаточных количеств J 132 порядка 0,5 кюри на таких установках, где нет работающих почти непрерывно реакторов с большой плотностью нейтронов, иди же где нет возможности облучать обогащенный уран.

PRODUCCIÓN DE YODO-132 A PARTIR DE TETRAFLUORURO DE URANIO IRRADIADO. Se ha seleccionado como m ate ria l a irradiar e l F4U en vez de m anió m eta l o de los óxidos de uranio utilizados por otros autores.

Las razones que han aconsejado la elección del F4U son las siguientes: a) tiene buena estabilidad térmica y radio lítica; b) es fácilm ente soluble en una solución de ataque constituida por ácido clorhídrico concentrado y ácido bórico; c) la reacción de disolución es suave y no desprende gases; y d) e l uranio queda disueltocom o U4+, en un m edio no oxidante, lo que perm ite una reducción selectiva d e l ácido telúrico adicionado como portador.

Todo e llo se traduce en una sim plicidad considerable del proceso de separación de l 132 Te. El m étodo de separación del аз* Te es e l siguiente: á) disolución dé l F¿U en e l m edio antes citado; b) reducción directa d e l ácido te lú rico con Cl2 Sn y*filtración; c) redisolucióri d e l T e con ácido c lorhídrico concentrado y agua oxigenada; d) reprecipitacióñ de l Te en m edio clorhídrico con Cl2 Sn o SO2 y filtración; y e) disolución final del Te en ácido n ítrico concentrado.

La solución nítrica de teluro, exenta de los productos de fisión no isotópicos con e l 132 T e, se fija sobre columna de alúm ina y dé ella seordéSa periódicamente e l 1321. En este sentido se han estudiado las condiciones de fijación del r*2Te y de elución del 1321 y se ha comprobado la pureza química y radioquímica del producto obtenido.

Este m étodo puede ser ap licado a cantidades re la tivam en te grandes de F4U, que com pensa los flujos integrales pobres que se consiguen en reactores de investigación, com o e l JEN-1, y perm ite por lo tan to , la obtención de cantidades suficientes de 1321, del orden de 0 ,5 с , a aquellas instituciones que c a rezc an de reactores de flu jo e levado a rég im en casi con tinuo , o de la posibilidad de irrad iar u ran io .enriquecido.

1. IN TR O D U C C IÓ N

E l 132I( de 2, 33 h, e s p ro d u c to de f is ió n h ijo d e l i32Te, de 77 h . L a p ro d u c c ió n de *32I, c a s i s ie m p re p a r a u so s m é d ic o s , s e v e r if ic a g e n e r a lm e n te s u m in is tr a n d o a l u s u a r io u n a c o lu m n a de a lú m in a e n l a c u a l e s t á f ija d o e l i32T e y de la c u a l s e o rd e ñ a in s i tu e l 132I co n so lu c ió n de NH 3

0, 01 M.E l 132T e n e c e s a r io p a r a p ro d u c ir e l 1321 s e ob tiene p ro c e sa n d o u ran io

i r r a d ia d o , en f o rm a de m e ta l o de óx ido , y s e p a ra n d o s e le c t iv a m e n te e l 132 Te; p o r p re c ip ita c ió n d e l e lem e n to con un re d u c to r adecuado [ 1, 2] , p o r e luc ión s e le c tiv a de l 132Te so b re co lum na de a lú m in a [ 3 ] , ,0 p o r d es tila c ió n d e l H 2T e que s é fo rm a d u ra n te e l a taq u e , con ác id o c lo rh íd r ic o , de u ra n io m é ta l i r r a d ia d o [4] .

PRODUCCIÓN DE 1321 A PARTIR DE F4U IRRADIADO 161

E l e s tu d io c r í t ic o de lo s t r e s p ro c e d im ie n to s de s e p a ra c ió n d e l 132 T e a n te s c itad o s , nos ha conducido a la conc lusión de que e l m á s adecuado p a ra n u e s t r a s fa c il id a d e s e x p e r im e n ta le s e s e l de la p re c ip ita c ió n s e le c t iv a del T e e le m e n to , a p e s a r de la s d if ic u lta d e s in h e re n te s a e s te m é to d o s e ñ a la d a s p o r a lg u n o s a u to re s [4]. E s ta s d if ic u lta d e s e s tá n b ie n fu n d ad a s y s e r e f i e r e n p r in c ip a lm e n te a l em p leo de ác id o n ítr ic o , n e c e s a r io p a r a a ta c a r la m u e s t r a i r r a d ia d a , ya que e s te ác id o , o su an ión , in te r f ie r e n p o s te r io r m e n te en la re d u c c ió n de l te lu ro a su e s ta d o e le m e n ta l.

N o so tro s hem os elud ido e l em p leo de ác ido n ítr ic o m e d ian te la e lecc ió n d e l te t r a f lu o r u r o de u ra n io (U F4 ) com o m a te r ia l a i r r a d i a r , e l c u a l s e d isu e lv e fác ilm e n te en e l m ed io no ox idante co n stitu id o p o r la m e z c la de ácido b ó r ic o y ác ido c lo rh íd r ic o .

L a in c ó g n ita m a y o r que in ic ia lm e n te p r e s e n ta b a e l e m p le o d e l UF4 , co m o m a te r i a p r im a p a r a la p ro d u c c ió n de 132 T e , e r a l a f a l t a de d a to s b ib lio g rá f ic o s con r e s p e c to a l c o m p o r ta m ie n to de e s te c o m p u e s to b a jo la ac c ió n de la ra d ia c ió n . No o b sta n te , hem os com probado que d o s is n e u tró n i- c a s d e l o rd e n de 5-1017 nv t y u n a p ro lo n g a d a e x p o s ic ió n d e l r e a c to r a la r a d ia c ió n g a m m a no a l te r a n e l c o lo r n i e l a s p e c to d e l U F 4 . Ig u a lm e n te , p e q u e ñ a s lá m in a s de a lu m in io y de c u a r z o in tro d u c id a s en e l i n t e r io r de m u e s tr a s de UF4 , que se han ir ra d ia d o con flu jos in te g ra le s del o rden citado, no m u e s t r a n a p a re n te m e n te a ta q u e de s u s s u p e r f ic ie s , lo que in d ic a que no hay fo rm a c ió n de f lú o r lá b il. P o r o tro lado , ta m b ié n hem o s com probado p o r te rm o g ra v im e tr ía que la e s tab ilid ad té rm ic a de e s te com puesto es buena, in c lu s o en a tm ó s f e r a de a i r e , h a s ta lo s 250°C [ 5] , p u e s a t e m p e r a t u r a s s u p e r io r e s , h a c ia lo s 300°C, e m p ie z a la p é rd id a de p e s o de la m u e s t r a y la o x id a c ió n d e l U1'4. P o r lo ta n to , h em o s ju zg ad o que la s p ro p ie d a d e s d e l UF4 son a p ro p ia d a s p a r a e l em p leo de e s te co m p u esto com o m a te r ia p r im a de la p ro d u c c ió n de 132 T e en u n r e a c t o r n u c le a r , t ip o p is c in a , co m o e l JE N -1 .

2. M ÉTO D O

2 . 1 . M a te r ia l a i r r a d i a r

E l UF4 em p leado p ro c e d e de f lu o ru ra c ió n p o r v ía s e c a d e l (NH4 )2 U 2O t co n HNH 4F 2 . E l a n á l is is q u ím ic o de e s te c o m p u e s to in d ic a que h ay 0, 4% de U en f o rm a U+6 y e l r e s to en f o rm a U +4. L a c a n tid a d de U 0 2 p r e s e n te e s m u y p eq u e ñ a , a p e n a s 0 , 1 %.

2 . 2 . I r r a d ia c ió n

L a ir ra d ia c ió n de la s m u e s tra s de UF4 s e r e a l iz a en tubos c i lin d r ic o s de p lo m o , no e s ta n c o s , de 1 m m de e s p e s o r ,, a lo ja d o s a su v ez en c a r tu c h o s e s ta n c o s de a lu m in io cu y a a tm ó s f e r a e s de H e y A en p a r t e s ig u a le s . E l t ie m p o de i r r a d ia c ió n s u e le s e r de u n a s e m a n a . D u ra n te e s te p e r io d o , e l fu n c io n a m ie n to d isc o n tin u o d e l R e a c to r JE N -1 a c u m u la f lu jo s in te g r a le s de 1, 5 a 5 • 1017 nv t, se g ú n la s p o s ic io n e s de i r r a d ia c ió n que s e u t i l ic e n .

162 M. BARRACHINA GÓMEZ

2 . 3 . S e p a ra c ió n d e l 132T e

E l UF4 ir ra d ia d o se d isu e lv e en ca lie n te con 10 m i de ácido c lo rh íd ric o c o n c e n tra d o (HC1 с) y 0, 4 g de ác id o b ó r ic o , p o r g ra m o de UF4 . Jun to con e l H CL с s e añaden 10 m g de ác ido te lú r ic o , in d ep en d ien tem en te de la c a n tid a d de UF4 a d is o lv e r . L a d iso lu c ió n s e v e r i f ic a en v a s i ja de a taq u e p r o v is ta de p la c a f i l t r a n te y d e l s is te m a de v a c ío -p re s ió n n e c e s a r io p a r a m a n t e n e r , a g i ta r o f i l t r a r líq u id o s ( fig u ra 1). E s ta o p e ra c ió n e s la m á s le n ta de to d o e l p r o c e s o y s u e le d u r a r a l r e d e d o r de 1 h p a r a 100 g de UF4 .

T e rm in a d a la d iso lu c ió n de la m u e s tr a , e l te lu ro se re d u c e a su es tad o e le m e n ta l con 5 m i de S nC l2 a l 10% en HC1 c . Se f i l t r a y s e la v a con agua a p r e s ió n . E l p r e c ip i ta d o de T e s e d isu e lv e en f r ío co n 1 m l de H 2 O 2 с y 3 m l de HC1 c, m e zc lad o s en e l m om ento de a ñ a d ir lo s . La so lución de te lu ro y un lavado con agua de la p la c a s e r e c ib e n so b re la segunda p la c a f il t r a n te , de p e q u e ñ a s id im e n s io n e s , que c o n tie n e 25 m i de so lu c ió n de S nC l2 a l 10% en HC1 c . L a p re c ip ita c ió n d e l Te e s de nuevo in m e d ia ta . Se f i l t r a , s e la v a con HC1 d ilu ido 1 :1 0 , dos v e c e s , y o t r a s dos v e c e s con agua d es tila d a .

E l p re c ip i ta d o de T e s e d isu e lv e f in a lm e n te co n 1 m l de HNO3 c . L a so lu c ió n n í t r ic a de te lu ro s e d iluye con 1 0 m i de agua, s e añade feno lfta le ína

Esquema del proceso de separación del ш Te

1. Depósito de agua para lavado a presión; 2. Embudo para la adición de reactivos (disolución y reducción); 3. Introducción de UF4 irradiado; 4. Vasija de ataque; 5. Manta de calefacción;

6. Placa filtrante No 4; 7. Llave de dos vías, con comunicación a la atmósfera;10. Colector; 11. Embudo con placa filtrante N: 4; 13. Vacfo; 14. Colección del producto final.

PRODUCCIÓN DE 1321 д PARTIR DE F4U IRRADIADO 163

y s e n e u t r a l iz a con so lu c ió n de NH3 1 : 3 , h a s ta que e m p ie z a e l v i r a j e . L a so lu c ió n de te lu r o a s í o b te n id a tie n e in v a r ia b le m e n te pH 8 , 3 -8 , 5, g r a c ia s a l ta m p ó n NH 4 N0 3 - N H 4OH que s e f o rm a , y e s tá e n c o n d ic io n e s de s e r p a s a d a d i r e c ta m e n te p o r l a c o lu m n a de a lú m in a p a r a f i j a r e l 13 2T e .

2 . 4 . F i ja c ió n d e l i32Te

. L a so luc ión de te lu ro n e u tra liz a d a , que con tiene e s te e lem en to a l e s tad o de T e O j2 , se f i ja so b re co lum na de a lú m in a de 20 m m de d iá m e tro y 20 m m de a l tu ra . L a a lúm ina em p leada, unos 5 g p o r co lum na, e s de la c a sa M erck , p a r a c ro m a to g ra f ía seg ú n B ro ck m an n . P a s a d a la so lu c ió n a c tiv a de te lu ro , l a co lu m n a s e la v a con 25 m i de ag u a d e s tila d a .

2 . 5 . E lu c ió n d e l 1321

E l i 32I fo rm a d o in s i tu s e o rd e ñ a p e r ió d ic a m e n te con 10 m i de NH 4C1 0, 01 M de pH 8 , 5. L a a c tiv a d a d de 1321 que s e p u e d e e lu i r d ep e n d e de la edad de l Ш Т е y de l in te rv a lo de tiem po tr a n s c u r r id o desde la ú ltim a elución, co n fo rm e ha sido d e s c r i to p o r o tro s a u to re s [3, 6 ].

2. 6 . P u re z a de l 1321 obtenido

Se h an id e n tif ic a d o e x a c ta m e n te e n e l e lu id o de la s c o lu m n a s lo s p e r io d o s de s e m id e s in te g ra c ió n d e l 131I y 132I y no s e h a d e te c ta d o p o r e s p e c t r o m e t r ía g am m a n inguna ra d ia c ió n e s p ú re a en lo s e lu íd o s en v e je c id o s . E l p o rc e n ta je de 131I que ac o m p a ñ a a l i32I e s e l p ro p io de la r e la c ió n i s o tó p ic a de l 131 Te y 132T e fo rm a d o s en la f is ió n d e l U [7], dependiendo tam b ién de la h is to r ia de la co lum na h a s ta e l m om ento de la elución que se co n s id ere [3,6] .

3. ESTUDIO EX PER IM EN TA L DE LA FIJACIÓN DEL l32Te EN COLUMNA DE ALUMINA Y DE LA ELUCION D EL *32I QUE SE FORMA

E n la b ib lio g ra fía se d e s c r ib e que la f ija c ió n del te lu ro so b re la colum na de a lú m in a p u ed e h a c e r s e en m e d io HNO3 N [ 3, 8 ], y m á s f re c u e n te m e n te en m ed io n itra to de pH 8 , [ 8 , 9, 10] . L a e lución de l 13ZI se hace c a s i s ie m p re con N H 3 0, 01 M [ 3, 6 , 8 , 9, 10].

C on e l f in de d i s e ñ a r la c o lu m n a de a lú m in a m á s id ó n e a p a r a e l s u m in is t r o d e l 132I p o r o rd e ñ o , h em o s e s tu d ia d o con d e ta lle ta n to l a f ija c ió n d e l ion T eO §2 s o b re la co lu m n a com o la e lu c ió n d e l 132I de la m is m a , m e d ia n te l a s ig u ie n te té c n ic a e x p e r im e n ta l.

3 .1 . T é c n ic a e x p e r im e n ta l

P a r a e l e s tu d io de la f ija c ió n d e l ion T e O j2 h em o s seg u id o un a té c n ic a a u to c ro m a to g rá f ic a c o n s is te n te en e l em p leo de co lu m n as de a lú m in a s u s c e p tib le s de s e r c o r ta d a s en ro d a ja s f in a s . L a s co lu m n as s e c o n s tru y e ro n co n tu b o s c i l in d r ic o s de p a r a f in a de 6 m m de d iá m e tro in te r io r , 2 m m de e s p e s o r y 60 m m de a l tu r a , ob ten id o s con un m o ld e . L os tu b o s de p a ra fin a ,


c a rg a d o s con a lú m in a , s e m o n tan en un s i s te m a decuado p a r a h a c e r p a s a r p o r e l lo s l a so lu c ió n de f i ja c ió n , d e 'la v a d o o de e lu c ió n , a l a v e lo c id a d d e s e a d a .

L a s c o lu m n a s de a lú m in a a s í o b te n id a s p u ed e n , lu e g o de la f i ja c ió n , c o r t a r s e en r o d a ja s de la a l tu r a que s e d e s e e , h a s ta de 0, 5 m m , y p e s a r l a a lú m in a s e c a s e p a r a d a de c a d a u n a de e l la s . Si s e m a r c a la so lu c io n de T eO §2 co n i32Te en e l m is m o e s ta d o ió n ic o , s e p u ed e d e te r m in a r , un a v e z a lc a n z a d o e l e q u i l ib r io t r a n s i to r io 132 T e - 13 21, la c a n tid a d de te lu r o f i ja d a a d is t in ta s a l tu r a s de la co lu m n a m id iendo la v e lo c id a d de co n ta je de la a lú m in a de ca d a u n a de la s r o d a ja s . E l n ú m e ro de f ra c c io n e s en que s e h a d iv id ido la s c o lu m n as de 60 m m e m p le a d a s e s de 20 a 30. De e s te m odo s e o b tien e una im ag en m uy d e ta lla d a de la d is tr ib u c ió n d e l te lu ro ad so rb id o so b re la co lum na, m e jo r desde luego de la que puede o b te n e rse p o r la té c n ic a de b a r r id o (scann ing ). E n la f ig u ra 2 s e r e p r e s e n ta una de e s ta s d i s t r i b u c io n es de f ija c ió n o b te n id as c o rta n d o la co lum na.

L a s c u r v a s de e lu c ió n d e l *321 s e h an e s tu d ia d o e m p le a n d o c o lu m n a s n o r m a le s de v id r io de 20 m m de d iá m e tro y 30 m m de a l tu r a y co lec tan d o f r a c c io n e s d e l e lu id o de v o lu m e n 'a d e c u a d o .

3 . 2. C a p a c id a d de l a s c o lu m n a s de a lú m in a p a r a l a f i ja c ió n d e l t e lu r o .

L a ca p ac id a d de f ija c ió n de una co lum na de a lú m in a puede c o n s id e ra rs e en p r in c ip io so la m e n te depend ien te de l pH s i, a p a r te de lo s iones H+ y OH",

Figura 2

Distribución del ion TeOj* fijado sobre una columna de alúmina

pH de fijación 8 ,5 ; flujo 2 m l/m in .cm 2 .

PRODUCCIÓN,DE A PARTIR DE F4U IRRADIADO 165

lo s d e m á s io n e s p r e s e n te s so n d e l t ip o NO3 , C l“ o a lc a l in o s que , co m o s e s a b e , t ie n e n p o ca a fin id ad p a r a a d s o r b e r s e s o b re la a lú m in a , o p ueden s e r f á c ilm e n te s u s t i tu id o s [ 1 1 ].

E l a n á l is is de la s d is t r ib u c io n e s de f i ja c ió n n o s m u e s t r a ( f ig u ra 2) que e l tr a m o h o rizo n ta l de la cu rv a , en e l que la can tidad de te lu ro adsorb ido p o r un idad de a d so rb e n te es co n s tan te , co rre sp o n d e a l n iv e l o co n cen trac ió n de s a tu ra c ió n con que la co lu m n a e s ca p az de f i j a r e l ion T eO j2 en la s c o n d ic io n e s e x p e r im e n ta le s e x is te n te s . E n la f ig u ra 3 s e r e p r e s e n ta n la s c a p a c id a d e s de f i ja c ió n en fu n c ió n de pH de la so lu c ió n de T e O ^2 que se f i ja , d e d u c id a s a p a r t i r d e l n iv e l de s a tu r a c ió n e n c o n tra d o en c a d a c a s o . L a zona ind icada , e n tre pH 2, 5 y 7, 5, c o rre sp o n d e a l in te rv a lo de in so lu b ilid a d d e l Т еО г, e l c u a l no p u ed e c o n s id e r a r s e p ro p ia m e n te com o zona ú t i l de f i ja c ió n , y a que, en e s te in te rv a lo , e l t e lu r o s e e n c u e n tra en l a s d o s e s p e c ie s q u ím ic a a c i ta d a s , com o T e O ^ у ТеО г, con un m áxim o de in so lu b ilid a d a pH a lre d e d o r de 4 [12].

E x p e rim e n ta lm e n te se ha com probado , com o e r a de e s p e r a r de acuerdo con la t e o r ía de a d so rc ió n , que la s c a p ac id a d es e n c o n tra d a s p a r a unas co n d ic io n es de f ija c ió n c o n c re ta s , dependen ap re c ia b lem en te de la concen trac ión de Т еО з2 de la so luc ión de a lim en tac ió n . En e s te sen tido , se ha determ inado la i s o te r m a de c a p ac id a d p a r a e l in te rv a lo de c o n c e n tra c io n e s de T eO j2 de que nos hem os se rv id o p a r a o b te n er lo s n iv e le s de sa tu ra c ió n a lo s d is tin to s pH, de 0, 1 a 3 m g Т е /m l, y se han n o rm alizad o la s capac idades en con tradas a la de 1 m g Т е /m l . L os v a lo re s a s i ob ten idos son los que se han r e p r e s e n tad o en la f ig u ra 3, c ita d a a n te r io rm e n te . De to d a s fo rm a s , e s ta c o r re c c ió n e s pequeña, m en o r d e l 1 0 %.

A n u e s tro m odo de v e r , la u til id ad de la c u rv a de ca p ac id a d de fija c ió n de la a lú m in a en función de pH no s e lim ita so lam en te a f a c i l i ta r la e lecc ió n de cond ic iones ó p tim as de f ija c ió n de la so luc ión de te lu ro , sino que tam b ién nos p ro p o rc io n a in fo rm ac ió n a c e r c a de l desp lazam ien to que s u f r i r á la banda de te lu r o a l p a s a r p o r la co lu m n a v o lú m e n e s c o n s id e ra b le s de la so lu c ió n e lu y en te d e l 132I, p u es cabe e s p e r a r que e l d esp laz am ien to s e a ta n to m ay o r cu an to m e n o r s e a e l n iv e l de s a tu ra c ió n c o r re s p o n d ie n te a la s co n d ic io n e s de e lu c ió n d e l 132 1 .

3. 3. D e sp la z a m ie n to de la b an d a de te lu r o en e l in te r io r de la co lu m n a a l e lu i r e l 132I

E l !321, que se fo rm a en la co lu m n a de a lú m in a a ex p e n sa s d e l 132T e que s e d e s in te g ra , s e e luye g e n e ra lm e n te con so lu c ió n 0, 01 M de NH 3 • E l pH de e s ta so lu c ió n e s 10, 5.

E l e fe c to d e s p la z a n te que l a so lu c ió n de N H 3 0, 01 M p ro d u c e s o b r e la b an d a de te lu r o p u ed e e x p l ic a r s e d e l s ig u ie n te m odo: s i in ic ia lm e n te e l io n T e 0 5 ¿ se f i ja a pH 8 , que e s e l c a so m á s f re c u e n te , la b an d a de TeO ^2

o c u p a rá en c a b e z a de co lu m n a una f ra n ja m uy e s tr e c h a , com o c o rre sp o n d e a l a a l ta c a p a c id a d de f i ja c ió n q u e la c o lu m n a t ie n e a e s te pH co n 42 m g Т е / g a lú m in a . A l p a s a r p o r la co lum na v o lú m en es su c e s iv o s de la so luc ión a m o n ia c a l e lu y e n te d e l i 32I, l a b an d a de T e O j2 s e r á r a b a ja d a de n iv e l y ex tend ida a lo la rg o de la co lum na, com o co n secu en cia de la m enor capacidad de la co lu m n a a pH 10, 5 p a r a f i j a r e l ion TeOjj'-2 , h a s ta so la m e n te 7 m g de


Figura 3

Capacidad de fijación de una columna de alúmina para e l ion T e O '2, en función de pH

Т е /g a lú m in a . A d em ás de e s te e fe c to de n iv e lac ió n , e l p a s o de la so lu c ió n a m o n ia c a l p r o d u c ir á ta m b ié n un e fe c to de d e s p la z a m ie n to y de ensanchar- m ie n to de la b anda , com o c o r re s p o n d e a to d a so lu c ió n que p a s a p o r la colum na y contiene iones d esp laz an te s en co n cen trac ió n a p re c ia b le . En n u es tro c a s o , e l io n d e s p la z a n te e s e l OH" que, com o s e s a b e , e s e l que o cu p a e l p r im e r lu g a r en la e s c a la de a f in id a d e s de f i ja c ió n de lo s a n io n es s o b re la a lú m in a [1 1 ]. L a e x p e r ie n c ia co n firm a , de to d a s fo rm a s , que e l d e sp la z a m ie n to deb ido a to d o s e s to s e fe c to s e s b a s ta n te im p o r ta n te , lo c u a l o b lig a a l em p leo de co lu m n as de a lú m in a de d im e n s io n e s " g ra n d e s" con e l f in de im p e d ir que a p a r e z c a te lu r o en la so lu c ió n e flu e n te .

D ado que la e le c c ió n de un nuevo e lu y en te e s tá co n d ic io n ad a ta n to p o r e l d e s p la z a m ie n to de l a b an d a de T eO j^ com o p o r l a c a p a c id a d de e lu ir e l 132I, s e ha te n id o p r e s e n te que e s te ú ltim o re q u is i to , e s d e c ir , la e lu c ió n d e l lá¿I, que s e e n c u e n tra a l e s ta d o de I - en m á s d e l 99% [13], puede r e a l i z a r s e ta m b ié n s in d if ic u lta d co n s o lu c io n e s de pH m e n o r que e l d e l 'N H 3

0, 01 M. P o r lo ta n to , p a r e c e ló g ic o que un e lu y en te d e l 132I, de pH m e n o r que e l ind icado , o fre z c a v en ta ja s m a n if ie s ta s p o r cuanto p ro d u c irá un d esp la z a m ie n to m e n o r de la b an d a de te lu r o , p e rm itie n d o co n e llo e l e m p leo de u n a co lu m n a de a lú m in a m á s c o r ta ; e llo h a r á a su v ez que la banda de e lu


c ió n d e l 132I a p a r e z c a a n te s , con lo c u a l s e n e c e s i ta r á u n a m e n o r ca n tid a d de e lu y en te p a r a o rd e ñ a r e l 132I.

E n la f ig u ra 4 s e r e p r e s e n ta n lo s d e sp la z a m ie n to s de b an d a p ro d u c id o s en se n d a s co lum nas de a lú m in a en la s que in ic ia lm en te se ha fijado la m ism a c a n tid a d de te lu ro a pH 8 , 5 y lavado con 25 m i de agua d e s tila d a /c m * (cu rva

Figura 4

D esplazam iento de la banda de teluro con distintos eluyentes para e l ОД

Curva 1. Distribución de fijación del ion TeO J*, después de lavar la columna con 25 m l/cm l de agua destilada. Curva 2. Desplazamiento de la banda in ic ia l (curva 1), producido por e l paso de

300 m l/c m 2 de agua destilada. Curva 3. Idem, por 300 m l/c m 2 de solución tampón de cloruro am ónico, pH 8 ,5 . Curva 4 . Idem , por 300 m l/c m z de solución NH 0 ,01 M, flujo 2 m l/m in-cm *.

8 *

1), d esp u és de p a s a r p o r e l la s e l m ism o vo lum en , 300 m l/c m 2, de d is tin to s e lu y en te s d e l 132I; agua d e s tila d a (cu rva 2), so luc ión tam pón de NH4CI-NH4OH,0, 01 M en N H 4CI, de pH 8 , 5 (cu rv a 3), y so lu c ió n de NH3 0, 01 M (cu rv a 4). C om o puede a p r e c ia r s e in m ed ia tam en te , la so luc ión de NH 3 0, 01 M extiende l a b a n d a de t e lu r o p o r lo m e n o s d o s v e c e s y m e d ia m á s que l a s o lu c ió n ta m p ó n de c lo r u r o a m ó n ic o y u n a s t r e s v e c e s m á s que e l a g u a d e s t i la d a . P o r lo tan to , em pleando e s to s ú ltim o s e lu y en te s p a r a e l 132I, s e puede a c o r t a r l a co lu m n a de a lú m in a a l a m ita d o a la t e r c e r a p a r te de su a l tu r a con l a se g u rid a d de que no te n d re m o s ion T e O j2 e flu en te en can tid ad m a y o r que l a que te n d r ía m o s con u n a co lu m n a de a l tu r a doble o t r ip le e lu id a con NH 3

0 ,0 1 M, a ig u a ld ad de v o lú m e n es p a sa d o s de lo s d is t in to s e lu y e n te s . E s ta s c o n c lu s io n e s so n v á l id a s g r o s s o m odo, in d e p en d ie n te m en te de la c a n tid a d de te lu r o in ic ia lm e n te f ija d a , p a r a la s c a n tid a d e s de te lu r o que s e m a n e ja n e n l a p r á c t ic a .


3 . 4 . E lu c ió n d e l 132I, fo rm a d o en la co lu m n a , con d is t in to s e lu y e n te s

A n te r io rm e n te nos h e m o s r e f e r id o a l a fa c il id a d con que e l 132I puede e l u i r s e de la c o lu m n a . E n la f ig u ra 5 s e han r e p r e s e n ta d o t r e s c u r v a s de e lu c ió n d e l 132I o b ten id as de la m is m a co lum na, en t r e s d ía s su c e s iv o s , con lo s t r e s e lu y e n te s cuyo e fe c to de d e s p la z a m ie n to s o b re la b an d a de te lu r o s e h ab ía e s tu d ia d o en e l a p a r ta d o 3. 3: e l NH3 0, 01 M (cu rv a 1), la so lu c ió n tam pón de c lo ru ro am ónico de pH 8 , 5 (cu rva 3) y e l agua d es tila d a (curva 2). L a s c u r v a s de e lu c ió n han s id o o b te n id a s , en c a d a c a so , p re v io la v ad o de a c o n d ic io n a m ie n to co n e l e lu y e n te en e s tu d io , h ech o e l d ia a n t e r io r a la e lu c ió n .

E n la f ig u ra 5 puede o b s e rv a rs e , de acu erd o con la p o s ic ió n de lo s m á x im o s de la s c u rv a s de e lu c ió n , que e l agua d e s tila d a e luye e l i32I con ta n ta f a c il id a d com o e l NH3 0, 01 M. E s te h echo , no o b s ta n te , e s m á s a p a re n te que r e a l , y a que se ha com p ro b ad o que la e fe c tiv id ad de e lu c ió n de l 132I p o r e l agua d e s tila d a d ism inuye g rad u a lm en te a m edida que e l núm ero de ordeños a u m e n ta . P a r e c e s e r que e l p o d e r e lu y e n te d e l ag u a e s tá re la c io n a d o con e l d re n a je de io n e s d e s a d so rb id o s de la co lum na, a ju z g a r p o r e l pH de lo s e lu id o s que d e c re c e g ra d u a lm e n te d esd e un v a lo r in ic ia l de pH 9.

y. . Figura 5

Curvas de elución del 1321

C u rv a l. Elución con solución de NH, 0,01 M. Curva 2. Elución con agua destilada.Curva 3. Elución con solución tampón de NH4C1 - NH4OH 0,01'M en NH4C1, ph 8 ,5 .

Velocidad de paso: 1 ,5 m l/m in . Columna de alúm ina de 20 m m de diámetro y 30 mm de altura.'

E l ren d im ie n to de ac tiv id ad e lu id a de 132I e s l ig e ra m e n te fa v o ra b le p a r a l a so lu c ió n de N H 3 0, 01 M f re n te a l de la de NH4 C I de pH 8 , 5, e n l a r e la c ió n de 1 : 0, 95, a p ro x im a d a m e n te .

3. 5. D ise ñ o de l a c o lu m n a de a lú m in a p a r a e l s u m in is t r o de 132I

C om o c o n s e c u e n c ia d e l p r e s e n te e s tu d io h em o s d ise ñ ad o u n a co lu m n a de 20 m m de d iá m e tro , con p la c a f i l t r a n te d e l № 2 , s o b re la cu a l s e fo rm a e l le c h o a d s o rb e n te con 5 g de a lú m in a M e rc k , p a r a c r o m a to g r a f ía seg ú n B ro ck m an n , y con ca p a c id a d p a r a c o n te n e r 10 m i de e lu y e n te . L a a lú m in a s e f i ja co n t e la de n y ló n y u n a n illo de m a te r i a l p lá s t ic o . L a a l tu r a to ta l e s de 8 cm .

L a e lu c ió n d e l 132I s e v e r i f ic a con 10 m i de so lu c ió n ta m p ó n de NH4C I- NH4 OH 0, 01 M en NH4 CI de pH 8 , 5.

E l pun to de r u p tu r a de e s ta s co lu m n a s de e n c u e n tra s itu a d o a m á s de 1000 m i de e lu id o , lo c u a l p e r m i te v e r i f ic a r con to d a s e g u r id a d m á s de 50 o rd eñ o s su c e s iv o s , de 1 0 m i, s in a p a r ic ió n de te lu ro en la so luc ión e fluen te .

• EXPRESIONES DE AGRADECIMIENTO

E l a u to r e x p r e s a su a g ra d e c im ie n to a la Ju n ta de E n e rg ía N u c le a r p o r la a u to r iz a c ió n co n ced id a p a r a la p re se n ta c ió n de e s te tr a b a jo y, a s im ism o , a lo s S re s . F e rn á n d e z C e llin i, de la C ru z y D om ínguez su c o la b o ra c ió n y a s i s te n c ia d u ra n te e l d e s a r r o l lo d e l m is m o .

R E F E R E N C I A S

STANG, L .G ., J r . , Production o f Iod ine -132, Nucleonics 12. 8(1954) 22.LEDDICOTTE, G. W ., T he Radiochem istry.of T ellurium . NAS - NS 3038 (1961) 12.RICHARDS, P . . A. Survey o f the Production a t Brookhaven N ational Laboratory of Radioisotopes for M edical Research, VII Rassegna In tem azionale Elettionica: e N ucleare , Roma (1960) 225.EAKINS, J .D . e t a l . , A New Production Process foi T e llu riu m -1 3 2 , In t. J . A ppl. Rad. Isotopes 9 (1960) 124.GASCO SANCHEZ,L.J. y FERNANDEZ CELLINI, R . . Control Term ogravim étrico de Productos In te rm edios de la M etalurgia del Uranio, Anales Real Soc. EspaJf. Fis. Q uím . 54 В (1958) 181. STIENNON-BOVY, R . L 'iode-132, BLG 4 4 (1 9 6 0 ).BLOMEKE, J .O . and TODD, M .F ., Uranium -235 Fission - Products as a Function of Therm al Neutron Flux, Irradiation T im e, and Decay T im e, ORNL-2127, Part I, V o l . l .GREEN, M .W . e t a l . , Separation of Io d in e -132 from Fission - Products, United States Patents N o .2 , 942, 943(1960).STANG, L. G . , Jr. e t a l . , D evelopm ent of Methods for the Production o f C erta in Short-Lived Radioisotopes, Radioisotopes in Sc ien tifica l Research, Pergamon Press, New York ¿ (1 9 5 8 ) 50.FEINE, U . , Separation of 13¿I on Alumina Columns and its Importance for M edical Radioiodine Diagnosis, Nuclear Med. 1 (1959) 159.HAYEK, E ., Adsorptions- und FSllungschiom atographie anorganischer Verbindungen, J. C hrom atog.2(1959) 334.PASCAL, P . , Nouveau T raité de C him ie M inérale, Masson e t C ié . , Paris.XHI (1960) 2016. STIENNON-BOVY, R. e t GELADI, G . , Analyse des formes sous lesquelles l'iod ine-132 apparaît lorsqu'il est séparé du tellure-132 par chromatographie sur alum ine, BLG 55 (1960).


[1][2J[33

[4]

[5]

[6] [V]

[ 8]

[9]

[10]

[ 11]

[ 12][ I3]

PRODUCTION OF IODINE-132 FROM IRRADIATED TEST FUEL ELEMENTS

H. SORANTIN, H. TITZE, H. BILDSTEIN AND N. GETOFF OSTERREICmSCHE STUDIENGESELLSCHAFT FÜR ATOMENERGIE,

VIENNA. AUSTRIA


PRODUCTION OF IODINE-132 FROM IRRADIATED TEST FUEL ELEMENTS. The preparation of iodine-132 from irradiated uranium is described. After irradiation and cooling, tellurium -132 is isolated from otherfission products and the uranium recovered. Extraction of iodine-132 from te llu r iu m -132 is performed e ith e r by an ion-exchange m ethod or by adsorption on p latinum . Purity tests for the product io d in e -132 are described and exam ples o f applications a re reviewed.

PRODUCTION DE L’IODE-132 A PARTIR DE CARTOUCHES DE COMBUSTIBLE EXPÊklMENTALES IRRADIÉES. Le m ém o ire d éc rit la préparation d 'io d e -132 â p a rtir d 'u ran iu m irrad ié . Après irrad ia tio n e t refroidissem ent, le te llu re-132 est isolé des autres produits de fission e t l'u ran ium est récupéré. On ex tra it l'iode-132 du tellure-132 soit par des méthodes d 'échanges ioniques soit par adsorption sur du platine. L'auteur d écrit des essais visant 3 déterm iner la pureté de l 'iode-132 obtenu e t passe en revue plusieurs applications.

ПРОИЗВОДСТВО И ПРИМЕНЕНИЕ ЙОДА-132, ПОЛУЧЕННОГО ИЗ ОБЛУЧЕННОГО УРАНА. Описывается приготовление йода-132 из облученного урана. После облучения и охлаждения теллур-132 отделяется от других продуктов распада и регенерируемого урана. Экстрагирование йода-132 из тедлура-132 производит-, ея или методом ионного обмена или при помощи адсорбции на платине. Дается описание способа определения чистоты изотопа йода-132 и приводятся примеры его применения.

PRODUCCIÓN DE YODO-132 A PARTIR DE ELEMENTOS COMBUSTIBLES IRRADIADOS. La m em oria describe la preparación de yodo-132 a partir de uranio irradiado. Después de la irradiación y del enfriam iento, e l te lu ro -132 se aisla de los productos de fisión resum es y e l uranio se recupera. El 1321 se ex trae de l 132Te por in tercam bio iónico , o por adsorción en p latino. La m em oria describe ensayos de la pureza d e l » ZI producido y presenta ejem plos de sus aplicaciones.

1. IN TR O D U C TIO N\

Io d in e -132 is in m any c a s e s m o re u se fu l fo r m e d ica l, c h e m ic a l and te c h n ic a l a p p l ic a tio n s th a n I 13i b e c a u s e of th e h ig h e r e n e rg y o f i t s y r a y s and i t s s h o r te r h a lf - l if e . In d iag n o stic te s t s , fo r exam ple , th e in te g ra l ra d ia tio n d o se to th e p a tie n t can b e re d u c e d by a f a c to r of 1 0 o r 1 0 0 w hen 1132 i s u se d .

Io d in e -132 can e a s i ly b e e lu ted f ro m g e n e r a to r s lo ad ed w ith i t s lo n g e r- liv in g m o th e r Tei32 ( 7 7 h) to supply iod ine fo r s e v e ra l w eeks. It i s p o ss ib le in such c a s e s to m ilk off f ro m a 1 0 -m c Tei32 s o u rc e 1 m e 1132 d a ily fo r the f i r s t tw o w eeks.

T h e p ro d u c tio n of I 132 in v o lv e s tw o s te p s : th e is o la t io n o f T e 132 f ro m u r a n iu m an d i t s f i s s io n p r o d u c ts an d th e s e p a r a t i o n o f th e d a u g h te r I 132 .

1 .1 . P r e p a r a t i o n o f Tei32

No a tte m p t i s m a d e in th is p a p e r to g ive a fu ll re v ie w of th e l i t e r a tu r e c o n c e rn in g th e s e p a r a t io n o f te l lu r iu m f ro m f is s io n p ro d u c ts and of io d in e

171

172 H. SORANTIN et al.

f r o m te l lu r iu m . H o w e v e r , a few of th e m o r e r e m a r k a b le r e c e n t p a p e r s a r e r e p o r te d .

S ince te l lu r iu m is u se d only a s a s o u rc e of iod ine i t does not have to be p r e p a re d in h igh sp e c if ic ac tiv ity .

A v e r y c o m m o n s e p a r a t io n m e th o d i s th e p r e c ip i ta t io n a s t e l lu r iu m m e ta l a f te r th e ad d itio n of c a r r i e r by s tro n g re d u c in g a g e n ts , su ch a s s u l p h u r d iox ide , stan n o u s ch lo rid e , h y d ro x y lam in e , h y d raz in e , e tc . F o r p u r if ic a tio n i t i s r e - p r e c ip i ta t e d and scav en g ed . A fte r th e s e s te p s y ie ld s of 50 to 90% a r e r e p o r te d by GLENDENIN U , 2], NOVEY [3] and DRUSCHEL [4].

EAKINS e t a l. [5] o b se rv e d th a t te l lu r iu m is re d u c e d to v o la t i le Н г Т е when i r r a d ia te d u ra n iu m is d is so lv ed in non -ox id iz ing ac id s , such a s h y d ro c h lo r ic a c id . N itro g e n , h y d ro g e n and h e liu m a r e s u i ta b le c a r r i e r g a s e s fo r tr a p p in g Н гТ е in f e r r i c c h lo r id e so lu tio n . In th e a b s o rb e r v e s s e l 90% of th e Т е can be re g a in e d by re d u c tio n and f i l te re d off a s m e ta llic te llu r iu m . R e -p re c ip ita t io n is n e c e s s a ry if c h lo r in e - f r e e iod ine fo r la b e llin g is needed .

T h e e le c tro d e p o s it io n of Т е i s d e s c r ib e d by HAISSINSKI [6 ], L E E and COOK (7 j and M AZUMDAR 18]. It is u se d fo r s p e c ia l p u rp o se s r a th e r th an f o r te l lu r iu m p ro d u c tio n .

T h e c a r r i e r - f r e e a d s o rp tio n of Т е 131,132 and M o99 on c h ro m a to g ra p h y a lu m in a f ro m a so lu tio n of i r r a d ia te d u ra n iu m in n i t r ic ac id i s c la im e d by TU C K ER , G REEN E and M U R R EN H O FF [9]. A fte r th e e lu tio n of Mo99 w ith a m m o n ia , 70% of th e f i s s io n t e l lu r iu m c a n b e s t r ip p e d off th e c o lu m n by c a u s t i c - s o d a so lu tio n .

1. 2. S e p a ra tio n of Ц 32 f ro m Т е 132

COOK, EAKINS and VEAL [10] ob ta ined ab so lu te ly te l lu r iu m - f re e iodine by d is t i l l in g it f ro m a s u lp h u r ic -a c id so lu tion of te llu r iu m in the p re se n c e of h yd rogen perox ide .. To avoid co n tam in a tio n of th e P 32 w ith I i31 th e d is t i l la t io n h a d to b e r e p e a te d tw ic e w ith in 12 h . T o p r e v e n t any lo s s o f io d in e w h ile r e g ro w in g , i t w a s o x id iz e d to io d a te , w h ich th e n h ad to b e r e d u c e d b e f o r e d is t i l la t io n .

S e p a ra tio n b y e m a n a tin g i s r e p o r te d by A R N O T T an d P E R U M A [11]. T h ey h a v e m o d if ie d th e a b o v e -m e n tio n e d m e th o d , k e e p in g th e io d in e p e r m a n en tly re d u c e d and d riv in g -o u t th e accu m u la ted am ount of I 132 by a s t r e a m of a ir - in an a lk a lin e tr a p .

W INSCHE, STANG and T U C K E R f i2 jd i s s o lv e d th e te l lu r iu m a c tiv i ty in 'à e u te c tic m ix tu re of L iC l and KC1, b u t th e y ie ld s of io d in e evo lved f ro m

■ th e m e l t 'w e r e n o t s a t i s f a c to r y ev en a t t e m p e r a tu r e s of about 370°C.' Io d in e i s a l s o e m a n a te d - f ro m ТеО г, h e a te d up to 700°C in an o x y g en

s t r e a m , a s u s e d in th e ro u tin e p ro d u c tio n of I 131 d e s c r ib e d by EVANS and STEV EN SO N [13] an d TA N G B O H L and SANSAHL 114]. In an a l te r n a t iv e mféthod of STANG e t a l . [15] Т еО г i s p r e c ip i ta te d f ro m a lk a lin e te l lu r iu m so lu tib n a f te r a c id if ic a tio n w ith a c e tic ac id , leav in g th e iod ine in the f i l t r a te . S m all a m o u n ts of te l lu r iu m , h o w ev e r, r e m a in in th e so lu tio n and c o n ta m in a te io d in e . T h e s tro n g b u ffe rin g a c tio n i s a lso a h an d icap fo r f u r th e r u se of th e io d in e so lu tio n .

A f te r s e p a r a t in g th e te l lu r iu m f r o m u ra n iu m and f is s io n p ro d u c ts , ROBSON [16] a p p l ie s an a lk a lin e s o d iu m - te l lu r i te so lu tio n to a co lu m n of

PRODUCTION I132 FROM IRRADIATED TEST FUEL ELEMENTS 173

ch ro m a to g ra p h ic a lum ina , on w hich 98% of th e te l lu r iu m conten t is ab so rb ed . T he c a p a c ity of th e a lu m in a w as d e te rm in e d to be 3. 5 m g Т е /g A12 0 3. A fter w ash in g w ith 1 -1 . 5 N 0. 01 am m o n ia th e co lum n (holding 20 g A I2O3) i s re a d y f o r ac tio n . A fte r r e -g ro w in g and e lu tin g w ith 20 m l 0. 01 N am m o n ia , 6.0,- 65% of th e w hole iod ine am ount can be s tr ip p e d off and does not contain m o re th an 10-3 % T e. R obson in v e s tig a ted c a r r i e r - f r e e so lu tion by p a p e r ch ro m a to g ra p h y and found th a t 99% of th e e lu ted iod ine w as in th e fo rm of I" . F u r th e r s tu d ie s show ed th a t c a r r i e r io d id e and io d a te w e re not a p p re c ia b ly a d so rb e d by th e a lu m in a , bu t a f te r p r e - t r e a tm e n t w ith te l lu r i te so lu tion ioda te w as found on th e co lum n . R obson th e re fo r e su g g e s te d th a t th e n o n -e lu a b le p e rc e n ta g e of io d in e m ig h t b e due to th e io d a te - fo rm .

TUCKER et a l. [9] a r e u s in g a s im ila r colum n w ith 10 g А12Оз. In cont r a s t to R o b s o n 's m e th o d i t i s lo a d ed w ith an a c id so lu tio n of c a r r i e r - f r e e te l lu r iu m and p r e p a re d b y w a sh in g w ith w a te r and d ilu te d a m m o n ia . 1132 i s ga ined by e lu tio n w ith 15 m l 0. 01 N am m o n ia and i s r e p o r te d to ho ld not m o r e th a n 0 . 0 0 1 % of th e to ta l am o ú n t of te l lu r iu m , i jh e u s e of c a r r i e r - f re e te l lu r iu m allow s th e p ré p a ra tio n of I 132 on a m u ltic u r ie sc a le . G E TO FF and P A R K E R [17] a r e p re c ip i ta t in g t e l lu r i c ox ide on g la s s - p a p e r , g la s s - w ool, e t c . , by a b s o lu te a lco h o l, w h ile th e io d in e i s s im u lta n e o u s ly e lu te d . T he p u r ity of th e io d in e so lu tio n i s ex a m in e d by p a p e r c h ro m a to g ra p h y and g am m a s p e c tro m e try . ^

M UNZE [18] i s u s in g a ca tio n ic .exchanger loaded w ith tin fo r th e s e p a r a tio n of io d in e - f re e te l lu r iu m . Tei3i.i32 0 2 i s s e p a ra tè d and p u r ifie d b y p r e - c ip ita tio n m e th o d s a f te r th e add ition of 1 0 -m g c a r r i e r , d is s o lv e d in 2 0 0 -m l d ilu te h y d ro c h lo r ic ac id and fed*onto th e co lum n. T he re d u c e d te l lu r iu m is in so lu b le and th e io d in e i s e lu ted w ith 15 m l of d is t i l le d w a te r , w hich, a f te r th e p ro c e d u re , co n ta in s 90% of the e x is tin g iod ine . F re ed o m fro m te llu r iu m w a s a s s u r e d b y s p e c t r a l - a n a ly t i c a l m e th o d s . T O T H [1 9 ].o b s e r v e d th a t io d in e i s a d s o rb e d on m e ta l l ic p la tin u m . Up t i l l now th i s p honom enon h a s b e e n u s e d b y T o th on ly f o r th e s e p a r a t io n o f 1131 f ro m T e is i f o r r o u t in e p ro d u c tio n o f th e f o r m e r .

2. IO D IN E -132 PRODUCTION IN TH E AUSTRIAN REA CTO R C EN TR E ATSEIBER SD O RF BY D IR ECT ELU TIO N FROM M ETA LLIC TELLU R IU M

R e la tiv e ly l a r g e a m o u n ts of t e l lu r iu m a r e r e g u la r ly a v a ila b le a t S e i- b e r s d o r f f ro m a n a ly t ic a l in v e s t ig a t io n s of i r r a d i a t e d fu e l e le m e n ts . F o r th e a n a ly tic a l s e p a ra t io n 1 0 -m g T e c a r r i e r i s added to s a m p le s of f i s s io n - p ro d u c t so lu tio n s, w hich a r e e v a p o ra te d to d ry n e s s w ith an in f r a - r e d b u rn e r . T h is p ro c e d u re i s re p e a te d tw ice-w ith H B r to .re m o v e th e n i t r ic ac id and to v o la tiliz e any se len iu m . The re s id u e is d isso lv ed in 3 M HCl. and th e te l lu r i u m p r e c ip i ta te d by su lp h u r d io x id e , / r e d i s so lv e d in a few d ro p s of c o n c e n t r a te d n i t r ic ac id , fum ed off, d isso lv ed again i n ,HCl, scavenged w ith Fe(OH^ and r e - p r e c ip i ta t e d w ith S0 2 - g a s a s m e ta l l ic te l lu r iu m . . U su a lly 80т 85% of th e c a r r i e r i s r e c o v e re d . •;

A m png th e f is s io n p ro d u c ts of U23à te l lu r iu m iso to p e s of m a s s n u m b e rs 125 to 134 have been, id e n tif ie d .. A fter i r r a d ia t io n th e iso to p e s T e 127, Tei3im and Tei32 a r e p red o m in an t.


A p art f ro m T e 132 only T e l32m and T ei3 i p ro d u ce an iod ine iso tope of fa ir ly sh o r t h a lf - lif e (8 . 05 d).

E lim in a tio n of Tei3im and T ei3l a s co n tam in an ts of T ei32by th e cho ice of su ita b le i r r a d ia t io n t im e s i s no t p o s s ib le , even w hen only th e p ro d u c tio n of Tei32 i s r e q u ir e d . T h e r a t io of th e n u m b e r of a to m s: (T ei3 i + Tei3im ) /T e i32 can , how ever, be red u c ed f ro m 0. 08 sh o r tly a f te r i r ra d ia tio n to 0. 0023 a f te r 250 h coo ling , a s i s show n by F ig . 1, w hich i l l u s t r a te s th e g row th and decay of th e T e - is o to p e s p ro d u ce d by i r r a d ia t in g 1 g u ra n iu m fo r 250 h a t a flux of10i2n cm -2s-i and coo ling fo r th e s a m e tim e .

1 g U irradiated with 1011 n c m "2sec " 1

I t w ill b e n o tic e d th a t s h o r t ly a f te r th e i r r a d ia t io n th e is o m e r ic s ta te s o f Т е 131 w ill b e p r e s e n t , to g e th e r w ith Т е 132 . N e a r ly p u r e I 132 h o w e v e r , can b e ob ta ined by m ak ing u s e of th e d if fe re n t g ro w th s of 1131 and 1132 in th e ir r e s p e c t iv e m o th e r s . If th e to ta l io d in e a c tiv ity i s re m o v e d f ro m a s a m p le w h ich h a s b e e n a llow ed to coo l fo r 250 h i t can b e se e n f ro m F ig . 2 th a t 1132 g ro w s a t a m uch f a s te r r a t e th an 1 Ш. A fte r 10 h 1132 h a s grow n to 95% of i t s m ax im u m a c tiv ity , w hile 1131 am oun ts to only 0. 07% of th e 1132 ac tiv ity . F o r th e p ro d u c tio n of I i 32 on ly su ch s e p a ra tio n m e th o d s can b e u se d w hich allow r e p e a te d a p p lic a tio n to e n s u re a low co n ten t of I131.

PRODUCTION I1* 2 FROM IRRADIATED TEST FUEL ELEMENTS 175

' Fig* 2

Regrowth of I132 and I131 after removal of to ta l iodine activity Sample: 1 g U Irradiation tim e: 250 h Cooling tim e: 150 h

If m e ta l l ic te l lu r iu m , a f te r i t s iso la tio n , i s p ack ed in to a n a r ro w g la s s cy lin d e r to fo rm a colum n, only about 1 0 % of the iodine p re se n t can be e lu ted w ith w a te r , a m m o n ia o r a b s o lu te a lc o h o l. T h e u s e of a b s o lu te a lc o h o l a s e lu a n t p ro d u c e s a t e l lu r iu m - f r e e io d in e so lu tio n .

We h av e t r ie d v a r io u s m e th o d s to im p ro v e th e iod ine y ie ld . F i r s t ly the a c tiv e te l lu r iu m w as re d is s o lv e d and p re c ip ita te d w ith su lp h u r d iox ide in th e p re s e n c e of in a c tiv e m e ta l lic te l lu r iu m to sp re a d th e ac tiv e te llu r iu m around a n u c leu s of in a c tiv e te l lu r iu m . In fu r th e r e x p e rim en t we o b se rv e d th a t p r e c ip ita tio n s w ith a s c o rb ic ac id gave a f in e r g ra in . H ow ever, only 20% of th e io d in e co n ten t could b e re c o v e re d by w ash ing w ith a lcoho l.

A fte r m ix in g th e t e l lu r i t e w ith sy n th e tic c a lc iu m s i l ic a te (m ic ro -c e U ) and re d u c tio n of th e te l lu r iu m , 60% of th e iod ine co n ten t could be e lu ted w ith 1 0 -m l a b so lu te a lco h o l, c o n ta in in g a few d ro p s of h y d ro g en p e ro x id e . T he m a in p a r t o f th e a c t iv i ty w a s found in th e f i r s t m i l l i l i t e r s . E lu tio n w ith0. 01 N am m o n ia , p h y s io lo g ic a l so d iu m c h lo r id e o r a s c o rb ic ac id so lu tio n s , gave no b e t te r r e s u l t s .

н! SÓRANTIN et al.

At p r e s e n t we a r e u s in g 1-2 g C a -s i l ic a te fo r 1 m g T e and we a r e ab le to p ro d u c e li3 2 0n a m i l l ic u r ie s c a le . T h e p u r ity of th e io d in e so lu tio n i s ch e c k e d by g a m m a s p e c t r o m e try , p a p e r c h ro m a to g ra p h y and r a d io a c t iv e d e c a y . No t e l lu r iu m c a n b e d e te c te d and th e I is i c o n te n t d o e s n o t e x c e e d0. 05% w hen m ilk e d off a t in te r v a l s of 12 h.

By c h e m ic a l m e th o d s i t h a s b ee n p io v e d th a t on an a v e ra g e 90% of th e io d in e i s in th e fo rm of I ' and 1% in th e fo rm of I 2, th e r e s t b e in g in h ig h e r o x id a tio n s ta te s .

A fte r d ilu tio n w ith s te r i l i z e d w a te r , e t c . , th e io d in e so lu tio n i s r e a d y f o r m e d ic a l u s e .

T h e s e p a r a t io n of io d in e and te l lu r iu m fo r th e p ro d u c tio n of 1132 f ro m u ra n iu m and f is s io n p ro d u c ts by ad so rp tio n on p la tinum is a lso being in v e s tigated a t S e ib e rsd o rf .

T h e e f fe c t o f d if fe r e n t t e m p e r a t u r e s , c o n c e n tra t io n s , s u r f a c e a r e a s and t im e s i s b e in g in v e s tig a te d . G ood a d s o rp tio n i s a c h ie v e d b u t e x p e r i m e n ts f o r th e s e le c t iv e d e s o rp tio n of I 132 a r e s t i l l in p r o g r e s s and w ill b e r e p o r te d l a t e r .

3. A PP L IC A T IO N S . O F I 132

Io d in e -1 3 2 i s b e in g a p p lied on an in c r e a s in g s c a le . In m e d ic in e i t i s u s e d fo r th y ro id u p ta k e t e s t s , c i rc u la t io n s tu d ie s f o r th e d e te rm in a t io n of b lood p la s m a v o lu m e , h ae m o d y n a m ic s tu d ie s , lo c a liz a tio n of th e p la c e n ta l s i te and fo r la b e ll in g a lb u m in s , e tc .

In in d u s t r ia l r e s e a r c h i t h a s b een u til iz e d fo r la b e llin g o ils , fa ts and to c h e c k m ix in g -e f f ic ie n c ie s . P a p e r s p u b lis h e d in th e l a s t f iv e y e a r s on th e p r e p a ra t io n and a p p lic a tio n of I I 32 h ave b ee n l i s te d by TU CK ER, e t. a l. [9].

4. A BSTRACT

A t th e A u s tr ia n R e a c to r C e n tre a t S e ib e rs d o r f , II32 i s p ro d u c e d f ro m th e re la t iv e ly la rg e am ounts of te llu r iu m w hich a re s e p a ra te d re g u la r ly fro m u ra n iu m and f is s io n p ro d u c ts fo r a n a ly tic a l p u rp o se s . M e ta llic te l lu r iu m is s p r e a d on sy n th e tic c a lc iu m s i l ic a te by re d u c tio n and th e iod ine fo rm e d can b e e lu ted w ith w a te r , 0. 01 N am m o n ia , p h y sio lo g ica l sod ium c h lo rid e so lu tio n , a s c o r b ic a c id o r a lco h o l. Y ie ld s o f 60% of th e io d in e p r e s e n t a r e ach iev ed w ith ab so lu te e th y la lco h o l. The p u r ity is checked by gam m a sp e c t r o m e t r y , p a p e r c h ro m a to g ra p h y and ra d io a c t iv e d e c a y . No s te r i l i z a t io n of th e I 132 so lu tio n i s n e c é s s á r y fo r m e d ic a l ap p lica tio n s w hen s te r i le flu id s a r e u s e d fo r d ilu t io n . T h e p r e p a r a t io n of I 132 by a d s o rp t io n on p la t in u m f ro m i r r a d ia te d u ra n iu m so lu tio n s is a lso b e in g in v e s tig a te d a t S e ib e rsd o rf .


We Wish to th a n k D r. Izb icky fo r h is a s s is ta n c e w ith th e g rap h th e o re t ic a l t r e a tm e n t of th e g row th and decay c u rv e s .

PRODUCTION I132 FROM IRRADIATED TEST FUEL ELEMENTS 177

R E F E R E N C E S

[1 ] GLENDENIN, L .E . , in: "Radiochem ical Studies, the fission Ptoducts", C .D . Coryell and N. Sugarman, E ds., M cGraw-Hill. N.Y. 3 IV ^9(1951) 1617.

[2] GLENDENIN. L .E . . in: "Radiochem ical Studies, the fusion Products", C .D . Coryell and N. Sugarman, E ds.. McGraw H ill. N .Y . 3 IV-9 (1951) 1620.

[3] NOVEY, T .B . , in: "Radiochemical Studies, the fission Products", C .D . Coryell and N. Sugarman, Eds., McGraw НШ. N .Y . 3 IV-9 (1951) 1611.

[4] DRUSCHEL, R .E ., "Tellurium Activity in aqueous or organic Solutions", M ethod No. 2 21841 (3-5 -54), ORNL M aster Analyt. M an ., T ID -7015(S ec .2).

[5] EAKINS, J , , ROBSON, I . and STOCKLEY, H .F . , "A new production Process for Tellurium -132", In t.J. A ppl.Rad. and Isot. 9 (1960) 124.

[6] HAISSINSKY, M .. J . Ç him . Phys. 53 (1956) 979.[7] LEE, D. and COOK, G .B ., "The Separation and Mounting of some fission Elements by Electrodeposition",

UKAEA Rep. AERE-C/R-430 (1949).[8] GHOSH MAZUMDAR, A . S . , "E lec tro ly tic Purification o f ca rrie r free te llu riu m T ra c e r" , P ro c .In d .

A cad. S ci. A48 (1958) 106-10.[9] TUCKER, W .D ., GREENE. M .W . und MURRENHOFF, A .P .. "Die Produktion von tragerfreiem T e-132 ,

Jod-132, M olybdan-99 und Technetium -99m aus neutronenbestrahltem Uran durch fraktionierte Sorption an A lum inium oxyd", Atomproxis 8 (1962). 163.

[10] COOK. G .B . , EAKINS, J . and VEAL, N .. "T he ftoduction and c lin ic a l A pplications o f I I » " , Int. J. Appl.Rad. and Isot. ^ (1956) 85.

[11] ARNOTT. D. G. andPERUM A, C .P . , "An em an atin g Source o f I I » " , In t. J., Appl. Rad. a n d lso t . 2(1957) 85.

[12] WINSCHE, W .E . , STANG, L .G . and TUCKER, W .D . . N ucleonics 8 3 (1951) 14.[13] EVANS, C .C . and STEVENSON, J . A . . British P a ten t Specifica tion 27780 54 (1954).[14] TANGBOHL, K . and SANSAHL, K . , "Joint Establishm ent for nuc lear Energy", Norway Rep. JENER 34

(1954). '[15] STANG. L .G ., TUCKER, W .D . and BANKS, H .O ., N ucleonics 12 ( 8) (1954) 22.[16] ROBSON, J . , AERE 749 (o c t. 1960).[17] GETOFF, N. und PARKER, W ., "Uber d ie H erstellung von Radiojod aus T ellu rsaure" ( in press).[18] MUNZE, P . , "E inneues V erfahren zur kon tinu ierlichen H erstellung von trag e rfre iem П » aus Tel»* ” ,

K em energ ie 3 6 (1960) 518.[19] TOTH, G . , "Production o f carrier-free I 131 from T ellu ric Acid by Adsorption” , Inorganic and N uclear

Chem istry 19 (S ept. 1961). *

D I S C U S S I O N S

L. STANG: I have a n u m b er of co m m en ts to m ake on y o u r p a p e r . Onepo in t r e l a te s to so m e of th e s ta te m e n ts you m a k e in co n n ec tio n w ith th e 1 131/1132r a t io . In th e f i r s t p la c e I d o n ’t th in k th a t io d in e - 131 c a n e v e r b e avo ided e n t ir e ly . Secondly , w h ile I a g re e th a t i t i s p o s s ib le to c o n tro l th e p 3 ] / 1132r a t io w ith in l im its , I don ’t th ink th a t th is can be done by any chem ica l p r o c e s s . T h e only w ay i t can b e done i s to ch o o se su ita b le i r r a d ia t io n and cooling t im e s a s w e ll a s a p p ro p r ia te in te rv a ls betw een su c c e s s iv e m ilk in g s . In c id en ta lly , bo th th e se fac ts a r e po in ted out in ou r e a r l ie r pub lica tio n s w hich you c ite in y o u r p a p e r .

In connection w ith y o u r r e fe re n c e to o u r e a r ly L iC l-K C l eu tec tic m ethod,I sh o u ld l ik e to add a s m a l l i te m of in fo rm a tio n . T h e y i'e ld s w e o b ta in e d w ith th a t te c h n iq u e w e re good w hen a g la s s v e s s e l w as u se d and p o o r w hen g r a p h ite o r p la t in u m v e s s e l s w e re u s e d . T h e t r o u b le w a s th a t th e g la s s v e s s e l s c r a c k e d a f t e r tw o o r t h r e e m ilk in g s .


E ls e w h e re in y o u r p a p e r you m e n tio n th a t R obson " su g g e s te d " th a t th e n o n -e iu a b le iod ine m ig h t be in th e fo rm of io d a te . I th ink it i s w o rth d ra w in g a t te n tio n to th e f a c t th a t th is p o in t w a s a c tu a lly p ro v e d - I th in k i t w as in 1955 o r th e re a b o u ts - in a P h . D. t h e s i s p r e s e n te d a t th e U n iv e r s i ty of N o tre D am e (Ind iana) by C. C um m iskey . D e ta ils of th is can be found in the p u b lic a tio n l is te d a s R ef. [1] in th e b ib lio g ra p h y appended to th e p a p e r I p r e se n te d e a r l i e r a t th is S em in a r ( th ese P ro c e e d in g s) .

F in a lly , i t s e e m s to m e th a t y o u r p r e s e n t m e th o d i s m u c h m o re c u m b e r s o m e th a n th e on e I o u tlin e d in m y p a p e r . Y o u r y ie ld i s th e s a m e a s o u rs o r s lig h tly l e s s - 60% as a g a in s t 65%. You say th a t 90% of y o u r iod ine is p r e s e n t in th e fo rm of iod ide ; in o u r c a s e th e f ig u re i s 100%. Y our p r o d u c t s o lu t io n c o n ta in s a lc o h o l, w h ich I th in k i t m ig h t b e o b je c tio n a b le to in je c t in to som e p a tie n ts , w h e re a s o u r p ro d u c t i s con ta ined in p h y sio lo g ica l s a lin e so lu tio n .

In c id e n ta lly , I g a th e re d f ro m w hat you sa id th a t you c o n s id e r a lcoho l to b e ad v an tag eo u s in th a t i t m a k e s th e so lu tio n s te r i le . I shou ld lik e to po in t out th a t o u r p ro d u c t so lu tio n is a lso s te r i le , and th a t i t can b e and h a s been in je c te d d ire c tly upon m ilk ing , w ithout any fu r th e r t r e a tm e n t o r au toclav ing .

H . SORANTIN-. W e do n o t c la im th a t o u r m e th o d i s b e t te r . T h e p o in t i s , h o w e v e r, th a t w e on ly h av e v e r y few c u s to m e rs . T o m a k e u s e of th e B ro o k h av en te c h n iq u e w ould in v o lv e u s in m o re p a p e r w o rk th a n o u r w hole iod ine supp ly is w o rth . F u r th e rm o re , o u r iod ine is re q u ire d fo r o ra l ap p lica tion .

L . STANG: I am not su g g e s tin g th a t you a c tu a lly p u rc h a se an H 32 g en e r a to r f ro m B ro o k h av en — although w e could of c o u rs e supp ly one — bu t m e r e ly th a t you ad o p t o u r m e th o d , w h ich i s a v a i la b le f o r an y o n e to u s e .

H. SORANTIN: W ith r e g a r d to th e p o in t you m a d e in c o n n e c tio n w ith th e 1131 /1132 r a t i o , o u r p a p e r m e re ly po in ted ' out th a t a t m ilk in g in te r v a ls of 12 h th e 1131 le v e l in th e 1132 so lu tio n r e m a in s low .

As fo r th e C um m iskey th e s is , even if i t i s c ited in th e a r t ic le you r e f e r to , i t h a s not to m y know ledge ac tu a lly been pub lished .

K. SCH EER: I th in k th a t in th e c a s e of in tra v e n o u s in je c t io n s a s a lin e so lu tio n i s p r e f e r a b le to any e th y la lc o h o l one. In any c a s e , a few p e r c e n t o f a lco h o l cou ld no t b e e x p e c te d to p ro d u c e a s te r i l i z in g e ffe c t.

W hat w e do to s t e r i l i z e o u r so lu t io n s i s to p a s s th e m th ro u g h a tig h t b a c te r i a l f i l t e r a t th e finail s ta g e of e a c h p ro c e d u re . W e do th is ro u tin e ly f o r a l l c h e m ic a l p r e p a r a t io n s in te n d e d f o r f in a l in tr a v e n o u s in je c t io n and a ls o f o r a lb u m in s o lu t io n s . W e h a v e n e v e r h a d any d if f ic u l t ie s w ith n o n - s t e r i l e s o lu t io n s .

M. DOUIS: C an you t e l l m e how you d e te rm in e th e f in a l a c tiv ity of th e 1132 ? Do you c a r r y out e lu tio n b e fo re co u n tin g th e I 132 o r do you som ehow co u n t th e I I 32 in th e p r e s e n c e of th e T e l 32 ?

H. SORANTIN: T h e re w as no d ifficu lty abou t th is b e c a u s e in o u r f i r s t e x p e r im e n ts w e u s e d a v e r y s m a l l g e n e r a to r , w h ich co u ld b e p la c e d in a w ell c o u n te r . M e a su re m e n ts w e re c a r r ie d out b e fo re and a f te r m ilk in g w ith a m u lti-c h a n n e l a n a ly s e r s e t on the iod ine peak.

I I

PREPARATION AND APPLICATION OF SHORT-LIVED RADIOISOTOPES

APPLICATION DE LA DÉSINTÉGRATION i32Te ± > 132I A LA PRÉPARATION DE MOLÉCULES MARQUÉES

J.-P.ADLOFFET M. ADLOFF-BACHER DEPARTEMENT DE CHIMIE NUCLEAIRE, CENTRE DE RECHERCHES NUCLEAIRES,

STRASBOURG, FRANCE


'APPLICATION OF THE 6-DECAY OF Tei32 F 0 R THE PREPARATION OF I«2 -LABELLED MOLECUI£S. The principal advantage of io d in e -132 in b io log ical and m ed ical applications, and in uses as a radioactive tracer, lies in its short half-life (T± = 2 .30 h) which, however, represents a serious drawback for the synthesis of labelled molecules. The paper shows that it is possible to take advantage of the chem ical reactivity of "nascent" iodine, formed during Ô-decay of te llu rium -132 , for rapidly preparing labelled species with a high specific activ ity . This reactiv ity comes partly from the sudden change of the a tom ic number during the decay, which in turn releases a highly excited iodine a tom , and partly from the in ternal conversion of the у-ray following the 8-em ission.

Iod ine-132 has to be foimed within the m edium to be labelled: the most convenient chem ical form for the parent compound is te llu rium -132 tetrachloride, which is soluble in a number of organic liquids. Several systems have been studied (arom atic hydrocarbons and derivatives, alcohols, e tc .) . After a few hours of contact, the organic solution is analysed by gaseous phase radiochromatography, and the separation of the various labelled species foimed by radiosynthesis can be effected by distillation after addition of carriers. The labelled products m ay be the results of isotopic exchange or hydrogen abstraction and fragm entation reactions. N ear-specific labelling can be achieved in some cases by the use of a suitable organic m edium .

APPLICATION DE LA DÉSINTÉGRATION l32T e£ > 132I A LA PRE'pARATION DE MOLÉCULES MARQUEES. La courte période de l ’io d e -132 (T^ = 2 ,30h)qu i justifie son intérêt en biologie, en médecine e t comme ind icateur radioactif, représente cependant un inconvénient m ajeur lorsqu'il s 'ag it de réaliser la synthèse de molécules m arquées. On m ontre qu’il est possible de tirer profit de la réactiv ité chim ique de l'iode « n a issan t » formé par la désintégration de te llure-132, en vue de préparer rapidem ent des molécules marquées avec une activ ité spécifique é levée . C ette réactiv ité provient de l 'énerg ie d 'ex c ita tio n de l'io d e , due â la brusque variation de la charge n uc léaire au cours de la d ésin tég ration ,a in si que de la conversion in te rne du rayonnem ent y succédant ¿ l'é m iss io n ô.

L 'iode-132 doit se former au sein du système â marquer: la forme chimique la plus appropriée du composé parent est le té trachlorure de te llu re-132 , soluble dans un certa in nombre de liquides organiques. Plusieurs systèmes ont ainsi é té étudiés (hydrocarbures aromatiques e t dérivés, alcools, e tc .). Après un contactdequelques heures, la solution organique est analysée par chrom atographie en phase gazeuse e t les différents composés, marqués par radiosynthèse, sont séparés par d istillation en présenced'entraîneurs. Les produits marqués peuvent ê tre le résultat de réactions d 'échanges isotopiques ou de substitution e t fragm entation. L'emploi d 'un m ilieu organique convenable perm et dans certains cas un m arquage pratiquem ent spécifique.

ИСПОЛЬЗОВАНИЕ р-РАСПАДА Te132 - J 132 ДЛЯ ПОЛУЧЕНИЯ МЕЧЕНЫХ МОЛЕКУЛ. Короткий период полураспада изотопа J132 (Tj = 2 , 3 часа), который оправдывает Интерес, проявляемый к нему в биологии и :медицине, и который является своего рода радиоактивным индикатором, представляет вместе с тем самое большое неудобство, когда идет речь о проведении синтеза меченых молекул. Отмечается возможность использования химической реактивности "дочернего” изотопа йода, образующегося в результате распада Те132 для быстрого получения меченых молекул с большой удельной активностью. Эта реактивность возникает из энергии возбуждения йода, подучаемой в результате резкого изменения заряда ядра в процессе распада, а также внутренней конверсии, сопровождающейся 3-излучением, следующей за Э-распадом.

Йод-132 образуется в системе, предназначенной для мечения; наиболее подходящей химической формой исходного компонента является четыреххлористый Те132 в определенном органичёском раство-

181

182 J.-P. ADLOFF et M. ADLOFF-BACHER

рнтеле* В связи о этим исследованиям подвергались несколько систем (ароматические углеводороды и производные, спирты и пр.), Посде облучения в течение нескольких часов органический раствор анализировался методом газовой хроматографии. Различные меченые компоненты отделялись путем дистилляции с носителем. Меченые продукты могут быть получены в результате реакций изотопного обмена, замещение и разложения. Использование подходящей органической среды позволяет в определенных случаях производить на практике специфическое мечение.

PREPARACIÓN DE MOLÉCULAS MARCADAS APLICANDO LA DESINTEGRACIÓN l« I . El corloperíodo de sem idesintegración de l yodo-132 (T | = 2 ,3 0 h), que justifica su interés en bio logía, m ed icina y como indicador radiactivo^ entraña no obstante un inconveniente grave cuando se trata de sintetizar moléculas marcadas. Los autores demuestran que es posible sacar provecho de la reactividad quím ica del yodo "naciente" formado por desintegración del teluro* 132 para preparar rápidam ente moléculas marcadas de elevada actividad específica. Esta reactiv idad se debe a la energía de excitación de l yodo, causada por la brusca variación de la carga nuclear durante la desintegración, así como por la conversión interna de las radiaciones y que suceden a la emisión ft.

El yodo-132 tiene que formarse dentro del sistema que se desea m arcar; la forma química más adecuada del compuesto m adre es e l tetracloruro de te lu ro -132, soluble en algunos líquidos orgánicos. De este modo se han estudiado varios sistemas (hidrocarburos arom áticos y sus derivados, alcoholes, e tc . . . . ) . Después de un contacto de algunas horas, la solución orgánica se analiza por cromatografía de gases y los diversos compuestos, m arcados por radiosíntesis, se separan por destilac ió n en presencia de portadores. Los productos m arcados pueden resultar d e reacciones d e in tercam bio isotópico o de sustitución y fragm entación. En ciertos casos, e l em pleo de un m edio orgánico conveniente perm ite lograr una m arcación prácticam ente específica.

1. INTRODUCTION

L a r é a c t iv i té c h im iq u e d e s a to m e s f o r m é s a u c o u r s d e r é a c t io n s de tr a n s m u ta t io n in d u ite s p a r d e s n e u tro n s ou p a r d e s p a r t i c u le s c h a r g é e s a so u v e n t é té u t i l i s é e a v e c s u c c è s p o u r p r é p a r e r d e s m o lé c u le s o rg a n iq u e s m a r q u é e s p a r d e s is o to p e s r a d io a c t i f s . P a r m i c e s r é a c t io n s d e r a d io - sy n th è se , le s p lu s connues so n t c e lle s du c a rb o n e -1 4 fo rm é p a r la réactiorç 14N(n, p)14C , du t r i t iu m fo rm é p a r le s r é a c t io n s 6L i(n , o)3H ou 3H e(n, p)3H e t d e s h a lo g èn es fo rm é s p a r c a p tu re ra d ia tiv e de n e u tro n s . L e s a to m e s ra d io a c t i f s i s s u s d e c e s r é a c t io n s so n t c r é é s av e c une é n e rg ie d e r e c u l é le v é e , t r è s s u p é r ie u re à l ’é n e rg ie d es lia is o n s c h im iq u e s , ce qui le u r co n fè re une ré a c t iv i té e x c ep tio n n e lle . I ls peuven t ro m p re le s m o lé c u le s du m ilie u d an s le q u e l i l s so n t p ro d u its e t s e re tro u v e n t d an s d es com p o sés ch im iques v a r ié s se lo n la n a tu re du m ilie u , le type de ré a c tio n n u c lé a ire , le s co n d itio n s e x p é r im e n ta le s .

J u s q u ’k p r é s e n t , l e s p r o c e s s u s de d é s in té g ra tio n sp o n tan ée p a r é m is s io n d ’un ray o n n e m e n t b ê ta ont tro u v é peu d ’a p p lic a tio n s en ra d io sy n th è se . MOURIN e t a l . [1] ont pu u t i l i s e r le s m o d ifica tio n s ch im iq u es accom pagnant la d é s in té g ra tio n b ê ta de 2iOBi(RaE) en 2iop0(R aF) pou r s y n th é tis e r d es co m p o sé s o rg a n o m é ta lliq u e s du polonium ; BAUMGARTNER e t a l . [2] ont m o n tré q u e l a d é s in té g ra t io n b ê ta d e 10sRu d a n s l e c o m p le x e d ic y c lo p e n ta d ié n iq u e du ru th én iu m co n d u isa it au d icyc lopen tad iény l-105Rh. C es exem ples m on tren t q u ’i l e s t p o s s ib le d e t i r e r p ro f i t d ’un e d é s in té g ra t io n b ê ta p o u r p r é p a r e r d e s co m p o sés m a rq u é s dont l a sy n th èse d ire c te e s t d iffic ile . L o rsq u e l ’atom e ra d io a c t i f i s s u d e l a d é s in té g ra t io n a un e p é r io d e c o u r te , c o m m e c ’e s t le c a s d e 132I, l a r a d io s y n th è s e de c o m p o sé s m a rq u é s p eu t ê t r e un e m é th o d e p a r t i c u l iè r e m e n t in té r e s s a n te .

APPLICATION DE LA DÉSINTÉGRATION 132T e j ; 1321 183

2. R É A C T IV IT É CH IM IQ U E D E 1321 F O R M É P A R D É SIN T É G R A T IO N D E l32Te [3]

2 . 1 . C a r a c t é r i s t i q u e s du s y s tè m e i ^ T e - 132!

i32T e fo rm é p a r f is s io n de 235 u a une p é r io d e de 77,7- h e t s e d é s in tè g re e n 132I p a r é m is s io n d ’un ray o n n e m en t b ê ta de 0,22 M eV, su iv i d ’un ra y o n n e m e n t g a m m a de 0 ,23 M eV . 132I s e d é s in tè g re a v e c un e p é r io d e de 2,3 h e t e s t f a c ile m e n t d é te c té p a r s e s ra y o n n e m e n ts b ê ta (p lu s ie u rs g ro u p e s de 2,12, 1,53 e t 1,16 M eV) e t g a m m a (de 0,53 à 2 ,2 M eV ).

2. 2. E ffe t de r e c u l

T an d is que le s a to m e s is s u s d ’une tra n s fo rm a tio n p rovoquée son t c r é é s a v e c un e é n e r g ie c in é tiq u e d e r e c u l é le v é e , l e s a to m e s f o r m é s p a r d é s in té g ra tio n b ê ta a c q u iè re n t l e u r é n e rg ie p r in c ip a le m e n t sous f o rm e d ’e x c ita tio n . L ’effe t de re c u l a s s o c ié à une d és in té g ra tio n b ê ta e s t peu im p o rtan t en ra is o n de la fa ib le m a s s e de la p a r t ic u le é m is e . Sa v a le u r m a x im a le e s t de 0,55 eV, à laq u e lle s ’a jou te l ’én e rg ie de re c u l due au rayonnem ent gam m a s u c c é d a n te l ’é m is s io n b ê ta , s o it 0,11 eV . L ’é n e rg ie to ta le de 0,66 eV e s t in su f f is a n te p o u r ro m p re d e s l ia is o n s c h im iq u e s , m a is p eu t cep en d an t e n t r a în e r une augm enta tion de l ’é n e rg ie de ro ta tio n ou de v ib ra tio n de la m o lé cu le con tenan t l ’a tom e ra d io a c tif .

2. 3. E ffe t de tra n sm u ta tio n

L a b ru s q u e v a r ia t io n de la c h a rg e n u c lé a i r e r é s u l t a n t de la d é s in té g ra tio n b ê ta e n tra în e un é b ra n le m e n t (ou « sh a k e off» ) de l ’éd ifice a tom ique . L ’im p o r ta n c e de c e tte p e r tu r b a t io n e s t é v a lu é e à une c e n ta in e d ’é le c t ro n - v o lts [4] ; e lle peu t a v o ir p o u r conséquence une io n isa tio n s im p le ou m ultip le de l ’a tom e fo rm é p a r la tra n sm u ta tio n .

2. 4. C o n v ers io n in te rn e du rayonnem en t gam m a

L a c o n v e rs io n p a r t i e l le du ra y o n n e m e n t g am m a en ray o n n e m e n t é l e c tro n iq u e p a r l ’é je c tio n d ’un é le c tro n d ’u n e couche p ro fo n d e d é c le n c h e une c a s c a d e d e t r a n s i t io n s p a r e f fe t A u g e r a v e c f o rm a t io n d ’un io n à c h a r g e m u lt ip le .

E n r é s u m é , 132I is s u de la d é s in té g ra tio n de i32Te e s t c r é é so u s fo rm e d ’un io n p o s i t i f d o u é d ’un e é n e r g ie d ’e x c ita t io n c o n s id é r a b le . C e t io n v a r é a g ir avec le m ilie u dans le q u e l i l a é té p ro d u it en p e rd a n t t r è s rap id em en t s a c h a rg e e t en s e d é s e x c ita n t ju s q u 'à a t te in d re l ’é q u i l ib re th e rm iq u e . E n r a is o n d e s ru p tu re s e t r é a r r a n g e m e n ts m o lé c u la ir e s q u i ac co m p a g n e n t c e s p ro c e s s u s , l e s fo rm e s ch im iq u e s so u s le s q u e l le s a p p a ra ît 132I p o u rro n t ê t re t r è s v a r ié e s .

3. PA R TIE EX PÉR IM EN TA LE

184 JrP . ADLOFF et M. ADLOFF-BACHER

3 .1 . G é n é ra lité s

L ’io d e -1 3 2 d o it ê t r e f o rm é au s e in du s y s tè m e à m a rq u e r ; l a f ó rm e ch im ique la p lus a p p ro p rié e du com posé p a re n t e s t le té tra c h lo ru re de te llu re à s t r u c tu r e c oval en te ou p a r t ie l le m e n t io n is é en TeC lg. I l e s t so lu b le dans d iv e r s l iq u id e s o rg a n iq u e s a u s s i b ie n p o la i r e s qu e non p o la i r e s : h y d r o c a r b u r e s , c o m p o s é s h a lo g é n é s , a lc o o ls , é th e r -o x y d e s , e tc .

3 . 2 . P r é p a r a t i o n du t é t r a c h l o r u r e de te l lu r e - 1 3 2

L e te l lu r e - 1 3 2 e s t f o u r n i ,p a r le C o m m is s a r ia t à l ’é n e rg ie a to m iq u e , en s o lu t io n a q u e u se a c id e ou a lc a l in e a v e c un e a c t iv i té s p é c if iq u e é le v é e (10 m c /m g de te l lu re ) . L a so lu tion de te l lu r i te de sodium e s t oxydée ra p id e m en t en te l lu r a te so u s l ’e ffe t du ray o n n em en t, ce qui n é c e s s ite sa réd u c tio n p ré a la b le p a r l ’a c id e b ro m h y d riq u e . A p rè s ad d itio n d ’une fa ib le q u an tité de te l lu r i te de sod ium com m e e n tra în e u r , le te l lu re é lé m e n ta ire e s t p ré c ip ité p a r le c h lo ru r e s ta n n eu x ; i l e s t e n s u ite f i l t r é , la v é , s é c h é e t f in a le m e n t p u r if ié p a r su b lim a tio n à l ’a b r i de 1 ’oxygèrie, dans une a tm o sp h è re d ’az o te . L e té t r a c h lo r u r e de te l lu r e e s t ob tenu p a r a c tio n d ir e c te du c h lo re à chaud s u r le te l lu r e é lé m e n ta ire . C ’e s t un co m p o sé s ta b le d an s l ’a i r se c , se d é co m p o san t k l ’h u m id ité , e t dont le po in t de fu s io n e s t de 224°. Il e s t d is so u s d an s le m ilie u o rg an iq u e c h o is i (c o n c en tra tio n : ~ 0 ,2 M) e t la so lu tio n peut ê t r e a n a ly sé e qu elq u es h e u re s p lus ta rd , lo rsq u e l ’éq u ilib re ra d io a c tif en tre le te l lu re e t l ’iode e s t r é a l is é .

3 .3 . A nalyse rad io c h ro m ato g rap h iq u e

L e s c o m p o sé s io d é s f o rm é s p a r r a d io s y n th è s e so n t a n a ly s é s à l ’a id e d ’un c h ro m a to g ra p h e en p h a s e g a z e u s e (fig . 1). L a c e l lu le à c o n d u c tiv ité th e rm iq u e e s t s u iv ie d ’un d é te c te u r de r a d io a c t iv i té c o n s ti tu é p a r deux c o m p te u rs p ro p o rtio n n e ls ch au ffé s p o u r é v i te r la condensa tion d es p ro d u its s é p a r é s , e t e n t re le s q u e ls c irc u le le gaz v e c te u r (He).

L ’e m p lo i d ’un c o m p te u r p ro p o rtio n n e l à c i rc u la t io n t r a v e r s é d i r e c t e m e n t p a r le gaz s o r ta n t de la co lonne c h ro m a to g ra p h iq u e s ’e s t é g a le m e n t r é v é lé s a t i s f a i s a n t . D an s ce c a s , i l e s t n é c e s s a i r e de m u n ir l e c i r c u i t du gaz v e c te u r d ’une a r r iv é e de m éthane à l ’e n tré e du com pteur [5].Ce com pteur e s t s e n s ib le à. c e r ta in e s im p u re té s t e l l e s que le s h a lo g é n u re s o rg a n iq u e s , m a is lo r s q u e c e s « p o iso n s » son t p r é s e n ts en q u an tité im p o n d érab le — c ’e s t le c a s d e s p ro d u its de ra d io sy n th è se — le fon ctio n n em en t du d é te c te u r n ’e s t p ra tiq u e m e n t p a s p e r tu r b é .

L a c h ro m a to g ra p h ie en p h a s e g a z e u s e av ec d o u b le d é te c tio n p e r m e t d ’e ffec tu e r s im u ltan ém en t une an a ly se ch im ique e t rad ioch im ique . L es avanta g e s d e c e t te te c h n iq u e on t d é jà é té s ig n a lé s [5 , 6 ] : la c e l lu le à c o n d u c t iv i té th e rm iq u e r é v è le le s c o m p o sé s p r é s e n ts en m a c ro q u a n ti té s , r a d io a c tif s ou non, ta n d is que le d é te c te u r de ra d io a c tiv ité ne donne une rép o n se qu e p o u r l e s m o lé c u le s m a rq u é e s . L a c o m p a ra is o n d e s h a u te u r s d e s p ic s

APPLICATION DE LA DÉSINTÉGRATION 132T eiU 1321 185

Figüire 1

R adiochrom atographie en phase gazeuse.

e n r e g i s t r é s p a r le s deux d é te c te u r s p e rm e t , a p r è s é ta lo n n a g e , d e d é t e r m in e r l ’a c t iv i té sp é c if iq u e d e s s u b s ta n c e s m a rq u é e s .

L ’id e n tif ica tio n d es p ic s de ra d io a c tiv ité e s t fa ite p a r co m p ara iso n avec le s v o lu m e s de r é te n tio n de c o m p o sé s connus in a c ti fs , d é c e lé s à. l ’a id e .d e la c e llu le 'k co n d u c tiv ité th e rm iq u e . Un ex e m p le de ra d io c h ro m a to g ra m m e e s t r e p r é s e n té s u r la f ig u re 2 .

L e s a n a ly se s ch ro m a to g rap h iq u e s ont é té e ffec tu ées dans le s cond itions s u iv a n te s : lo n g u e u r de la c o lo n n e : 1 m ; p h a s e s ta t io n n a ir e : s te r c h a m o l im p ré g n é d ’h u ile de s i l ic o n e ci 20%; t e m p é r a tu r e v a r ia b le d e 4 4 . к 200°.

D e s f r a c t i o n s de 50 ^1 d e l a so lu tio n de i32Te C I4 s o n t in je c té e s d a n s le ch ro m a to g rap h e ; le so lv an t et le s d iv e rs io d u res ra d io a c tifs son t e n tra în é s p a r le^gaz v e c te u r ta n d is q u e T e C li^ se lo c a l i s e au s o m m e t de la co lo n n e .

3 .4 . A p p lic a tio n ci l a p r é p a ra t io n de m o lé c u le s m a rq u é e s

, L e s c o m p o sé s o rg a n iq u e s m a rq u é s p a r 132l so n t fo rm é s e t a n a ly s é s en l ’a b s e n c e d ’e n t r a în e u r s . I l e s t p o s s ib le de l e s r e c u e i l l i r s u c c e s s iv e m e n t e t d ir e c te m e n t à la s o r t ie de la co lonne c h ro m a to g ra p h iq u e , à l ’a id e d ’une d e s m é th o d es su iv a n te s : ■a) A d so rp tio n s u r du c h a rb o n a c tif ou du ta m is m o lé c u la ire .b) P ié g e a g e d a n s l ’io d u re in a c ti f c o r re s p o n d a n t; l ’a c t iv i té sp é c if iq u e e s t

a lo r s d é te rm in é e p a r la q u a n tité d e 132T e m is e en oeuv re e t du v o lu m e du liqu ide de p iég eag e . C e tte techn ique de co llec tio n a une e ff ica c ité t r ^ s ' é le v é e , in d é p e n d a n te d e s d im e n s io n s du pïfege, de l a q u a n t i té d ’io d u r e in a c ti f , du d é b it du gaz v e c te u r .

186 J-P . ADLOFF et M. ADLOFF-BACHER

Figure 2

R adiochrom atogram m e d 'une solution de “ *T eC U dans le toluène.

c) P ié g e a g e d a n s un so lv a n t a p p r o p r ié .L a p ré p a ra t io n d e s m o lé c u le s m a rq u é e s p eu t se f a i r e indépendam m en t

d ’une s é p a ra tio n c h ro m a to g ra p h iq u e , p a r d is t i l la t io n en p ré s e n c e d ’e n t r a î n e u r s [7]. L a te ch n iq u e u t i l is é e e s t a l o r s la su iv a n te :1a so lu tio n de 132T e C l 4

e s t t r a i té e p a r S 0 4H2 3N p o u r e x t r a i r e le té tr a c h lo ru re , pu is p a r une so lu tion aq u eu se de su lf ite (0,01 M) e t d ’io d u re de sod ium (0,1 M) p o u r é l im in e r 1321 non l ié o rg an iq u e m en t [8]. A p rè s ad d itio n d e s e n tra în e u rs convenab les , le s d iv e rs e s e sp è c e s m a rq u é e s peuvent Ê tre s é p a ré e s p a r d is tilla tio n frac tio n n ée , le c a s éch éan t so u s p re s s io n ré d u ite .

4. RÉSULTATS

L ’a n a ly se ra d io c h ro m a to g ra p h iq u e r é v è le un c e r ta in n o m b re d e c o m p o sé s m a rq u é s p a r 132I, dont la fo rm a tio n peu t ê t r e exp liquée p a r d es ru p tu r e s d es lia is o n s C -C , C -H , C -C l e t С -O su iv ie s de ré a c tio n s de r é a r r a n g em en t, d ’in te rc e p t io n de ra d ic a u x , de su b s titu tio n , a in s i que p a r d e s r é a c tio n s d ’éch an g e iso to p iq u e . L a d iv e r s i té d e s p ro d u its f o rm é s r e f lè te la r é a c t iv i té d e 132I; c e p en d a n t i l e s t p o s s ib le de l im i te r c o n s id é ra b le m e n t le n o m b re d ’e s p è c e s ra d io a c tiv e s p a r un choix convenable du m ilieu o rgan ique .

4 .1 . S o lu tions de 132T eC l4 d an s le s a lco o ls

L ’ex a m e n d e s c o m p o sé s m a rq u é s o b te n u s av ec d iv e rs a lc o o ls a l ip h a - t iq u e s r é v è le p lu s ie u r s f a i t s s a i l la n ts (f ig ,3 ):a) L ’iode-132 so u s fo rm e o rg an iq u e ne r e p r é s e n te q u ’une f ra c tio n r e la t iv e

m e n t fa ib le (50% au m a x . ) de l a q u a n tité en é q u il ib re av e c 132T e; c e tte f r a c t io n e s t v a r ia b le d ’un a lc o o l à l ’a u t r e .

b) L e n o m b re de co m p o sés io d és e s t p ra tiq u em e n t éga l au n o m b re d ’a to m es de ca rb o n e de l ’a lco o l.

c) L a p lu s g ra n d e p a r t i e d e 13liI o rg a n iq u e s e r e tr o u v e d an s l ’io d u re ay an t un a to m e de c a rb o n e de m o in s que l ’a lco o l (sau f p o u r l ’a lco o l m éthylique q u i co n d u it e x c lu s iv e m e n t à СН з1321. L ’a tta q u e d e l a m o lé c u le d ’a lc o o l

APPLICATION DE LA DÉSINTÉGRATION 132T eJÜ 1321

CH,OH

C2 H5I

30 V.

CH3I

69,5V.

C2 H5OH

C2H5I

CH3 IC3 H7 I

ffl.7*/. 57.3V. 2 3 '/ .

C3 H7OH

C3 H7 I

c 4 h 9 iW| 1 1 V . |

CH3 I

| 12^ V .| 5 9 ’/ . 19 V.

CH3 I

C3 H7 I isoC2H5 I

| 1° V . | 77,7%

C4 H9 OH

C3 H7OH ¡so

CjH7I iso

C4 HgIiSOC2M5 ̂ CH3‘v 3n 7A

5,5*/.21,2% <4,5% | 10.6% | 1-------- i W.2%

187

Figure 3

D istribution des iodures m arqués form és par désin tégration deUZTeCl4 dans divers alcools.

188 J.-P. ADLOFF et M. ADLOFF-BACHER

p a r I32I se fa i t p ré fé re n tie U e m e n t s u r la lia iso n e n tre le ca rb o n e p o r te u r du g ro u p e m e n t h y d ro x y le e t le c a rb o n e v o is in . C e f a i t p eu t s ’e x p l iq u e r p a r le c a r a c t è r e d ip o la ire de l ’a lc o o l dont le c a rb o n e en a c o n s titu e un p ô le a t t r a c t i f p o u r l ’ion 1З21+,

4 .2 . S o lu tio n s d e 132T e C l4 d an s le s c o m p o sé s a ro m a tiq u e s

E n s o lu t io n b e n z é n iq u e on o b s e rv e une r é a c t io n de s u b s t i tu t io n a v e c fo rm a tio n d ’iodobenzfene m a rq u é . L e re n d e m e n t o rg an iq u e e s t fa ib le : 23%.

L e s r e n d e m e n ts de m a rq u a g e so n t p lu s é le v é s lo r s q u e le noyau a r o m a tiq u e p o r te d é jà un g ro u p e m e n t é le c tro n é g a t i f . C ’e s t a in s i que d a n s le сЫ огоЬепгЪпе 35% de 132I e s t l ié o rg an iq u e m en t so u s fo rm e d ’iodobenz'fene.

L ’a n a ly s e r 'a d io c h ro m a to g ra p h iq u e d ’u n e so lu tio n d e 132T e C l 4 d a n s le to lu è n e e s t r e p r é s e n té e s u r la f ig u re 2. L e s re n d e m e n ts m o y e n s so n t le s su iv a n ts , e x p r im é s en p o u rc e n ta g e de 132I o rg a n iq u e :

132T e C l4 d a n s CH3 -C 6H5

4 .3 R é a c tio n s d ’éch an g e iso to p iq u e

On s a i t qu e le s r é a c t io n s d ’éch an g e iso to p iq u e e n t r e I" e t l e s io d u re s a ro m a tiq u e s sont ex trê m e m e n t le n te s ; c ’e s t a in s i que la p é rio d e de l ’échange e n t r e CgHgl e t 131I a é té é v a lu é e k 400 a n n é e s [9]. C et échange d ev ien t c e pendant im p o rta n t d ès la te m p é ra tu re o rd in a ire et peu t a tte in d re en quelques h e u r e s la v a le u r de 40% d an s le s y s tè m e 132T e C I 4 - iodobenz'fene. D es r é a c tio n s d ’éch an g e iso to p iq u e ont é g a le m e n t é té o b s ë rv é e s dans le sy s tè m e i 32T e 0 4 N a 2 - iodobenz'fene - a lc o o l, to u te fo is av ec un re n d e m e n t in f é r ie u r .

Ce type de ré a c tio n p o u r ra it ê t re u ti l is é pou r le m arquage de m olécu les p lu s c o m p le x e s te l le s que le r o s e b en g a le ou le d io d ra s t , c o m p o sé s b io lo g iq u e s u t i l i s é s en d ia g n o s tic du fo ie e t du r e in qu i ont é té m a rq u é s p a r 131I k l ’a id e d ’u n e 'r é a c t io n d ’échange iso to p iq u e [ 1 0 ].

5. CONCLUSION

L e s q u e lq u e s e x e m p le s p r é s e n té s m o n tre n t q u e l e s « a to m e s ch au d s» d ’iode-132 ont une ré a c tiv i té su ffisan te pour e n t r e r en com binaison chim ique avec le m ilieu dans le q u e l i ls sont fo rm é s , so it p a r des ré a c tio n s de su b s t itu tio n a c c o m p a g n é e s de ru p tu re m o lé c u la ir e , s o it p a r échange iso to p iq u e .

R E M E R C I E M E N T S

Nous r e m e rc io n s M lles G . K auffer, G . M artin e t Y. Q u iri qui ont effectu é le s p r é p a ra t io n s de t é t r a c h lo r u r e de te l lu r e m a rq u é a in s i que de n o m b r e u s e s a n a ly s e s p a r d is t i l la t io n e t ra d io c h ro m a to g ra p h iq u e s .

С Н 3-СбН4132 1 63 , 8%C6H5132I 10, 8%CH3132I 16, 5%f o rm e s non id e n tif ié e s 8 , 9%

APPLICATION DE LA DÉSINTÉGRATION 132T e i ; 1321 189

R E F E R E N C E S

[1] MOURIN, A .N ., NEFEDOV, V .P ., ZAITSEV, V. M. e t GRATCHEV, S .A ., "Ispol' zovanie himiSeskih izm enenij pri processah beta-raspada RaE dlja sinteza elementorganifceskih soedinenij polonija"(Utilisation des transformations chimiques dans les processus de désintégration b£ta du RaE pour la synthèse des composés organiques du p o lon ium ), C hem ical effects of N uclear Transformations II, AIEA, Vienne (1960) 183.

[2] BAUMGARTNER, F . , FISCHER, E. O. e t ZAHN, U . , "D i-cyclopentadienylrhodium (II) durch Elem ent- umwandlung aus D i-cyclopentadienylruthenium (II) ", Chem . Ber. 91 (19.58) 2336.

[3] BACHER, M. e t ADLOFF, J. P . , «R éac tiv ité chimique de node-132 formé par désintégration du tellure~132», C .R .A cad .S ci. 255 (1962) 304.

[4] SERBER, R. e t SNYDER, H. S . , "The effect of atom ic binding on nuclear reaction energies", Phys. Rev. 87 (1952) 152.

[5] WOLFGANG, R* e t ROWLAND, F .S . , "Rajdioassay by gas chrom atography of tritiu m - and carb o n -14- labe led com pounds", A nal. C hem . 30 (1958) 903.

[6] ADLOFF, J. P . , «T echniques e t applications de la radiochromatographie en phase g azeu se» , J.Chromat.6(1961) 373.

[7] HALPERN, A. e t SOCHAKA, R . , "The c h em ic a l s ta te of I^31 from Tel3 1 labe led d ib en zy lte llu rid e" , J. Inorg. N ucl. C hem . 23 (1961) 7.

[8] KENESHEA, F. J. e t KAHN, M ., "The state of chem ical combination of I131 formed by neutron irradiation of tellurium in organic liquids", J.Am er. Chem . Soc. 74 (1952) 5254.

[9] MANNO, P.J. e t JOHNSTON, W .H ., "Extremely slow reactions. The isotopic exchange reaction between iodobenzene and potassium iodide", J.A m er.C hem .Soc. 79 (1957) 807.

[10] HENRY, R ., DEBUCHY, D. e t JUNOD, E . , «Synthèses spéciales de certains composés organiques iodés» , Rapport CEA n® 1784 (1960).

D I S C U S S I O N

Is th e to lu e n e m a in ly r in g - la b e l le d o r s id e - c h a in -

I t i s la b e l le d in th e b e n z e n e r in g .

K. FR Ü H A U F: la b e l le d ?

J . P . A D L O F F :

t

SOME TECHNIQUES FOR ISOLATING AND USING SHORT-LIVED RADIOISOTOPES

F. NELSON AND K.A. KRAUS CHEMSTRY DIVISION, OAK RIDGE NATIONAL LABORATORY, OAK RIDGE,

TENN., UNITED STATES OF AMERICA


SOME TECHNIQUES FOR ISOLATING AND USING SHORT-LIVED RADIOISOTOPES. Radioisotopes of a

large number of elem ents have been used extensively a t Oak Ridge National Laboratory in ion exchange,solub ility and other physical-chem ical studies. The use of short-lived radioisotopes in such studies has necessitated developm ent not only of rapid methods of preparing and purifying radioisotopes but also of special techniques for obtaining pertinent inform ation in a re la tively short tim e , often w ithin a few minutes.

Some recently-developed methods are described for preparing and purifying short-lived isotopes, particularly those originating from neutron-irradiated m aterials, including fissionable elem ents. The la tte r, of course, a re convenient sources of a number of useful short-lived radioisotopes, e . g . , M o " , Те132, and methods are described for rapidly isolating these and other fission products in a earner-free state by ion exchange. Methods of separating short-lived daughter ac tiv itie s from long-lived parents by "m ilk ing" techniques, in which the paren t is strongly adsorbed on organic or inorganic ion exchange m a te ria ls , a re also described and ty p ica l exam ples discussed, for ex am p le , m ilk ing o f 1. 7 -h In113 (from Sn113) and 2 . 6-m in Balâ/ (from Cs197).

Two applications involving the use of short-lived tracers in ch em ica l studies a re described. T he first is a ’’packed bed" technique for rapidly m easuring the solubilities of sparingly soluble salts which have been tagged with tracers. Some recen t results obtained by the m ethod on the solubility of LaF3 in HCl and HCIO4 solutions a re described. T he second is a rapid m ethod for m easuring diffusion coefficients in liquid systems. T h in , porous po rcela in frits a re saturated w ith solution containing a radioisotope, then rapid ly e lu ted w ith solution not contain ing tracer. Diffusion coeffic ien ts m ay be ca lcu la ted from the decrease of counting ra te of the frit w ith t im e ,a f te r calib ra tion with a m a te ria l of known diffusion rate. Because of the short diffusion path used, die measurements m ay be com pleted in substantially less tim e by this method than by conventional techniques, for exam ple diaphragm cell or capillary tube methods.

QUELQUES METHODES D’ISOLEMENT ET D’UTILISATION DES RADIOISOTOPES A COURTE PERIODE. Un grand nom bre de radioisotopes sont la rgem ent u tilisés au Laboratoire na tiona l d 'O ak Ridge pour des re cherches physico-chim iques, no tam m ent sur les échanges d 'ions e t la so lub ilité . L’em plo i de radioisotopes â courte période pour ces travaux a nécessité la m ise au point non seulem ent de m éthodes de préparation e t de purificatio n a c cé lé ré e s , m ais aussi de techniques spéciales perm ettant d 'ob ten ir des informations valables dans un temps re la tivem ent court, souvent de l'o rdre de quelques m inutes.

Les auteurs décrivent certaines méthodes nouvelles de préparation e t de purification d 'isotopes ¿cou rte période, notam m ent d ’isotopes qui proviennent de m atières irradiées par les neutrons, e t en particulier d'élém ents fissiles. Ces derniers perm etten t év idem m ent d 'o b ten ir fa c ilem en t plusieurs radioisotopes ¿ c o u r te période très u tiles , par exem ple " M o e t i32Te. Le m ém oire expose les méthodes qui perm ettent d ’isoler ces corps, ainsi que d 'autres produits de fission par échange d ’ions, sans entraîneur; il décrit aussi la séparation des produits de filiation â courte période de leurs ascendants â longue période par des procédés de « mulsion » qui consistent ¿adsorber fortem ent l'ascendant sur des échangeurs d'ions organiques ou m inéraux; des exem ples typiques sont exam inés: m ulsion de 113Sn pour en e x tr a ir e 113 In (1 ,7 h) e t de 137Cs pour en ex tra ire 137Ba (2 ,6 m in).

Les auteurs décriven t deux app lications com portan t l 'em p lo i d 'in d ica teu rs ¿ courte période pour des recherches chim iques. La prem ière perm et de mesurer rapidem ent les solubilités de sels m odérém ent solubles qui ont é té m arquées à l 'a id e d 'u n ind ica teu r (m éthode de la « couche com pacte » ; les auteurs indiquent les résultats obtenus récem m en t ¿ l 'a id e de c e tte m éthode pour la m esure de la so lub ilité de LaF3 dans des solutions d 'a c id e chlorhydrique e t d 'ac id e perchlorique. La deuxièm e est une m éthode rapide pour la mesure des coefficients de diffusion dans des systèmes liquides. De m inces frittes de porcelaine poreuse sont saturées avec une solution contenant un radioisotope, puis rapidement éluées avec une solution necontenantpasd 'indicateur. On peut calcu ler les coefficients de diffusion d ’après la dim inution du taux de com ptage de la fritte avec

191

192 F. NELSON and K. A. KRAUS

le temps, après étalonnage avec une m atière dont on connaît la vitesses de diffusion. En raison du court chemio de diffusion u tilisé , les m esures peuvent ê tre fa ites en un laps de tem ps re la tiv em en t plus court que par les m éthodes classiques (c e llu le à d iaphragm e ou tube cap illa ire ).

НЕКОТОРЫЕ МЕТОДЫ ПОЛУЧЕНИЯ И ИСПОЛЬЗОВАНИЯ КОРОТКОЖИВУЩИХ ИЗОТОПОВ. Радиоизотопы многих элементов широко используются в Окридхской национальной лаборатории для изучения ионного обмена, растворимости и при других физико-химических исследованиях. Использование короткоживущих изотопов в таких исследованиях обусловило необходимость разработки не только быстрых методов приготовления и очистки радиоизотопов, но и специальных методов получения соответствующей информации в сравнительно короткое время, часто в течение нескольких минут.

Описываются некоторые, недавно разработанные методы получения и очистки короткоживущих изотопов, в частности изотопов, получаемых при нейтронном облучении материалов, в том числе расщепляющихся элементов. Последние, безусловно, являются надежными источниками ряда полезных ксротко- живущих изотопов, например, Мо8в и Те132. Описываются ыетоды быстрого выделения этих изотопов с помощью ионного обмена, а также методы отделения короткоживущих дочерних изотопов от исходных долгоживущих изотопов с помощью специальной техники выделения ("доения" ), когда исходный изотоп быстро адсорбируется на органических и неорганических ионообменных материалах. Обсуждаются также типичные случаи, например, выделение In113 с периодом полураспада 1,7 часа (из Sn113) и Ва137 с периодом полураспада 2,6 мин (из Св137).

Описываются два вида применения короткоживущих индикаторов в химических исследованиях. Во- первых, метод "уплотненного слоя" для быстрого измерения растворимости умеренно растворимых солей, меченных индикаторами. Приводятся некоторые новые данные, полученные с помощью этого метода, в отношении растворимости LaF3 в растворах НС1 и Н С Ю 4 . Во-вторых, описан быстрый метод измерения коэффициентов диффузии в жидких системах. Тонкие пористые фарфоровые фритты насыщаются раствором, содержащим радиоизотоп, затем быстро промываются раствором, не содержащим индикаторы. Коэффициенты диффузии могут быть рассчитаны из уменьшения скорости счета фритта с течением времени после сравнения с материалом с известной скоростью диффузии. Благодаря короткому сроку диффузии, с помощью этого метода измерения могут быть проведены за значительно более короткое время, чем с помощью обычных методик, например, с помощью камеры с диафрагмой или капиллярных трубок.

ALGUNAS TÉCNICAS DE AISLAMIENTO Y EM PI£0 DE RADIOISÓTOPOS DE PERIODO CORTO. En el Oak Ridge N ational Laboratory se v ienen u tilizando frecuentem ente radioisótopos de muchos elem entos para lle v a r a cabo estudios de in te rcam bio ión ico , so lubilidad y de otros procesos fisicoquím icos. El em p leo de radioisótopos de período corto obligó a encontrar m étodos rápidos para prepararlos y purificarlos, así com o técnicas especiales para conseguir datos útiles en un tiem po relativam ente corto, con frecuencia pocos minutos.

La m em oria describe algunos de los m étodos .recien tem ente perfeccionados para preparar y purificar isótopos de período corto , espec ia lm en te los que proceden de m a te ria le s irradiados con neutrones, incluso elem entos fisionables. Como es natural, estos Ultimos constituyen una m ateria prim a adecuada para obtener toda una serie de radioisótopos de período corto m uy ú tiles , com o son e l " M o , y e l ш Т е , y se describen métodos para a islar rápidam ente por in tercam bio iónico estos y otros productos de fisión exentos de portador. T am bién se describen m étodos para separar e lem entos descendientes de período corto de sus precursores de período largo por técnicas de separación repetida en las que e l precursor se adsorbe fuertem ente en sustancias intercambiadoras de iones orgánicas o inorgánicas, y se discuten ejemplos típicos, como la separación repetida del 113In de 1,7 h (a partir de 118Sn) y del 137Ba de 2 ,6 min (a partir de 13TCs).

La m em oria describe dos técnicas que em plean indicadores de período corto para efectuar estudios quím icos. La prim era es la de lecho com pacto , que sirve para m edir rápidam ente la solubilidad de sales poco solubles previam ente m arcadas. Se c itan algunos resultados relativos a la solubilidad del LaF3 en soluciones de HC1 у НСЮ4 , obtenidos rec ien tem en te por este m étodo . La segunda constituye un m étodo rápido para m edir coefic ientes de difusión en sistem as líquidos. Consiste en saturar fritas delgadas de porcelana con una solución que contenga un radioisótopo que se eluye después rápidám ente con una solución no m arcada. A partir de la disminución del índice de recuento de la frita en función del tiem po, se pueden calcular los coeficientes de difusión de otros productos después de calib rar con una sustancia cuya velocidad de difiisión sea conocida. Como e l recorrido de difusión es muy corto, es posible realizar las mediciones en un tiem po mucho más breve por este método que por las técnicas clásicas, por ejem plo, las celdas con diafragma o los métodos que emplean tubos capilares.

ISOLATING AND USING SHORT-LIVED RADIOISOTOPES 193

D u rin g th e la s t ten y e a r s , ra d io iso to p e s of a la rg e n u m b é r of e le m e n ts h av e b ee n u s e d e x te n s iv e ly by u s a t th e O ak R id g e N a tio n a l L a b o ra to ry in a v a r ie ty of p h y s ic a l - c h e m ic a l an d in o rg a n ic s tu d ie s p r im a r i l y b e c a u s e ra d io - is o to p e t r a c e r te c h n iq u e s g re a tly s im p lify a n a ly tic a l p ro b le m s . W ith a p p r o p r ia te g a m m a - e m it t in g is o to p e s and s u i ta b le co u n tin g e q u ip m e n t a n a n a ly s is (of a liq u id sam p le ) m ay be co m p le ted in a v e ry few m in u te s . W ith b e ta o r alpha, e m it te r s , w h e re counting of liqu id sa m p le s is u su a lly not p r a c t ic a l , so m ew h at m o re t im e i s r e q u ire d , although even th e n an a n a ly s is ca n u su a lly be co m p le ted m o re ra p id ly than w ith s ta n d a rd a n a ly tic a l te c h n iq u e s . T he tre m e n d o u s sav ing of tim e re a liz e d by the u se of rad io iso to p e techn iques m a k e s l a r g e - s c a l e s y s te m a t ic s tu d ie s p o s s ib le . F o r c o m p a ra t iv e s tu d ie s th e a b ility to re a c h e x tre m e ly low c o n c e n tra tio n s w ith t r a c e r s is a lso a d i s t in c t ad v an tag e .

T he ex ten t to w hich w e have u til iz e d ra d io iso to p e s in p h y s ic a l-c h e m ic a l and c o m p ara tiv e in o rg an ic s tu d ie s ( e .g . , ion exchange, s e p a ra tio n s c h e m is t r y , e v a lu a tio n of in o rg a n ic s o lid s ) i s d e m o n s tr a te d in F ig . 1, w h e r e th e . iso to p e s u se d , and th e i r h a lf - l iv e s , a r e show n. T he f ig u re in c lu d es iso to p es of a lm o s t a l l e le m e n ts and, in m any c a s e s , m o re than one iso to p e of a g iven e lem e n t.

S e le c tio n of t r a c e r s w a s b a s e d on th e fo llo w in g c r i t e r i a : a v a i la b i l i ty of t r a c e r (hence, em p h as is on t r a c e r s ob ta ined by n e u tro n ir ra d ia tio n ) , e a se of p u r ific a tio n , s im p lic ity of counting (hence, em p h as is on g a m m a -e m itte rs ) an d s im p lic i ty of d e c a y c h a r a c t e r i s t i c s . T h e h a l f - l i f e of th e t r a c e r s w a s u su a lly on ly of se c o n d a ry im p o r ta n c e . W hile lo n g - liv e d iso to p e s a r e o ften p r e f e r r e d , b ecau se once p re p a re d and p u rified they m ay be used conven ien tly f o r long p e r io d s of t im e , s h o r t- l iv e d iso to p es have w ide a p p lica b ility and, a s show n in F ig . 1, m a n y is o to p e s u s e d by u s h a v e h a l f - l iv e s of l e s s th a n about th r e e d ay s , i. e . , in th e con tex t of th is S em in a r they m a y b e co n s id e red s h o r t - l iv e d . T h e se s h o r t - l iv e d iso to p e s a r e u s e fu l not on ly if th e y a r e th e only ones a v a ila b le fo r a g iven e le m e n t, but a ls o in m any o th e r c a s e s . F o r e x a m p le , th e y a r e o f te n p r e f e r r e d b e c a u s e th e y c a n b e p r e p a r e d in h ig h s p e c if ic a c t iv i ty by s h o r t i r r a d ia t io n s ev e n if th e e le m e n t b o m b a rd e d h a s on ly a s m a ll c a p tu re c r o s s - s e c t io n . R a p id ly -d e c a y in g s h o r t- l iv e d t r a c e r s can e a s ily be id en tified in m ix tu re s th ro u g h th e i r decay r a te s . C om pos it io n and s ta b il i ty of so lid m a te r ia l s , f o r ex a m p le , in o rg a n ic e x c h a n g e rs , m ay be s tu d ied by in c o rp o ra tin g s h o r t- l iv e d t r a c e r s in th e m a te r ia ls d u rin g p r e p a ra tio n ; a f te r th e i r decay th e m a te r ia ls can be u se d w ith o th e r t r a c e r s to c h a r a c te r iz e o th e r p r o p e r t ie s . .

In th e p a s t w e have te n d ed to avo id iso to p e s w ith h a l f - l iv e s of l e s s th an a few h o u r s an d u s e d th e m on ly u n d e r s p e c ia l c i r c u m s ta n c e s . H o w e v e r i t a p p e a r s th a t in th e a b s e n c e of lo n g e r - l iv e d t r a c e r s su c h v e r y s h o r t - l iv e d iso to p e s a r e s t i l l e x t re m e ly u se fu l f o r a n a ly tic p u rp o s e s and c o n s id e ra b le sa v in g of t im e m ay r e s u l t c o m p a re d w ith c o n v e n tio n a l m e th o d s of a n a ly s is . U n d e r s p e c ia l c o n d itio n s , f o r e x a m p le in k in e tic s tu d ie s w ith p a r e n t - d au g h te r p a i r s , iso to p es w ith h a lf - liv e s a s sh o r t a s a second pose no sp e c ia l c o m p lic a tio n s .

W hen u s in g r a d io is o to p e s of e x t r e m e ly s h o r t h a l f - l i f e in p h y s ic a l - c h e m ic a l s tu d ie s ^ f re q u e n t p r e p a r a t io n of th e t r a c e r i s r e q u i r e d , an d on e m ig h t w onder if a n á ly s is by n e u tro n a c tiv a tio n m igh t not be m o re a p p ro p r ia te .

HA

LF-L

IFE

(d

)

104

103

102

10

1

10'1

_210 2 10 18 25 30 36 40 45 50 54 60 65 70 75 80 86 90 95 100

He Ne A Kr Xe RnATOMIC NUMBER

F ig . l

Some isotopes used in com para tive physica l-ino rgan ic studies

194 F.

NELSON and

K. A. K

RAU

S


W ithout in tend ing to im pugn in any w ay the v e r s a t i l i ty and u s e fu ln e s s of th is p o w erfu l tech n iq u e , we b e liev e th a t fo r the type of p h y s ic a l-c h e m ic a l s tu d ies to be d is c u s s e d in th is p a p e r n e u tro n a c tiv a tio n a n a ly s is is l e s s d e s i r a b le . W hen a l a r g e n u m b e r of a n a ly s e s a r e n ee d ed , su c h a s in co lu m n e lu tio n s tu d ie s , a c tiv a tio n m e th o d s beco m e te d io u s s in c e ev e ry sam p le w ill r e q u ire i r r a d ia t io n . F u r th e r , in m a n y e x p e r im e n ts a d d i tio n a l e le m e n ts á r e o ften p r e s e n t , so m e of th e m in e x tre m e ly l a r g e a m o u n ts , f o r e x a m p le w hen the e le m e n t of i n t e r e s t i s d is s o lv e d in a c o n c e n t ra te d s u p p o r tin g e l e c t r o ly te so lu tion . T he m ed ium m ay then becom e ex tre m e ly rad io a c tiv e du ring i r r a d i a tio n and c o m p lic a te n e u tro n ac tiv a tio n a n a ly s is . In c o n tra s t, when r e la t iv e ly s h o r t- l iv e d t r a c e r s a r e p re p a re d , th e re i s a w ide ch o ice of c h e m ic a l o r p h y s ic a l fo rm of the e le m e n t to be i r r a d ia te d . F u r th e r , if th e e x p e r im e n ta l te c h n iq u e s ar,e ra p id , a s in g le b o m b a rd m e n t m ay be u se d f o r s e v e r a l m e a s u r e m e n ts .

T h e p u rp o s e of th e p r e s e n t p a p e r is to .d e s c r ib e an d i l l u s t r a t e so m e of th e m e th o d s w h ich w e h av e u se d f o r p r e p a r in g and p u r ify in g s h o r t- l iv e d iso to p e s , p a r t ic u la r ly th o se o r ig in a tin g f ro m n e u t ro n - i r r a d ia te d m a te r ia ls , a n d to i l l u s t r a t e so m e of th e r a d io c h e m ic a l te c h n iq u e s u s e d f o r o b ta in in g p h y s ic a l - c h e m ic a l in fo rm a tio n e x p e d itio u s ly .

1. T E C H N IQ U E S O F P R E P A R IN G AND P U R IF Y IN G R A D IO ISO T O PE S

W hile m o s t of th e t r a c e r s u se d w e re o b ta in e d f ro m th e R a d io iso to p e s D iv is io n of th is L a b o ra to ry w e h av e found th a t, f o r s h o r t - l iv e d t r a c e r s , i t is often m o re convenien t to c a r ry out o u r own b o m b ard m en ts and p u r ific a tio n s . In such c a s e s only m ic ro c u r ie am oun ts a r e p re p a re d a t a tim e , and the te c h n iq u e s f o r h an d lin g t r a c e r s a t th is le v e l of a c t iv i ty a r e s im p le an d do n o t r e q u i r e r e m o te c o n t ro l . , S m a ll le a d c a r r i e r s g iv e s u f f ic ie n t s h ie ld in g f o r m o s t p r e p a r a t io n s p r a c t i c a l ly im m e d ia te ly a f t e r th e b o m b a rd m e n t .

W ith a h ig h -flu x r e a c to r such a s the ORR (Oak R idge R e se a rc h R e ac to r; f lu x c . 1 0 W n/cm .2 s), s e v e r a l m ic r o c u r ie s of a c tiv i ty m a y b e p ro d u c e d in a few m in u te s by i r r a d ia t in g s m a ll f r a c t io n s of m i l l ig r a m s of a p p ro p r ia te e le m e n ts . H o w ev er, even a t m u ch lo w e r f lu x e s , f o r ex a m p le , 10 11 , m o re th an 0. l/*c , a su ffic ie n t q u an tity fo r m any ty p e s of e x p e r im e n ts , can be p r o duced in 10 m in w ith s m a ll am o u n ts ( e . g . , 10~4m o le s) of a la rg e n u m b e r of e le m e n ts . T y p ic a l ex a m p le s a r e N a24 , K42 , Ni^5 , C u M , Ga72 , A s 76 , B r82 , P d 109 , C d 115 , L a140 , P r 142 and o th e r r a r e e a r th s ; 0.1 /uc of S i31 o r M o " m ay be ob ta ined in l e s s th an j h .

T h is l i s t m ay be ex tended th ro u g h th e u se of c e r ta in s e p a ra te d iso to p e s . F o r ex am p le , the y ie ld of 2 .6 -h S i31 d u rin g a s h o r t b o m b a rd m en t m ay be su b s ta n tia lly in c re a s e d by th e u se of the iso to p e S i30 , th a t of 4 . 7 -d С a47 th rough th e u s e of C a46 , and 2 . 6 - h N i6 5 th ro u g h N i64 . If ev en s m a ll q u a n t i t ie s of XJ236 a r e av a ila b le th e v e ry conven ien t g a m m a -e m ittin g t r a c e r , 6 . 75 -d U237 , can be p re p a re d , a lthough it w ill r e q u ir e a se p a ra tio n f ro m f is s io n p ro d u c ts (se e a ls o F ig . 6 ).

T h e i r r a d ia t io n te c h n iq u e s a r e s im p le an d r a p id w ith p n e u m a tic - tu b e f a c i l i t i e s . T h e m a t e r i a l to b e i r r a d i a t e d i s p la c e d in a m e ta l o r p la s t i c " ra b b i t" a s show n in F ig . 2. T h e se c o n ta in e rs m ay be in s e r te d and rem o v ed


GRAPHITEREACTOR L.I.T , R. O.R.R.

Flg. 2

Irrad iation containers

f ro m th e r e a c to r in a m a t te r of se c o n d s . T he ta r g e t m a te r ia l m ay be w ra p ped in a lu m in iu m fo il o r , if v o la tile p ro d u c ts a r e expected du rin g i r ra d ia t io n i t ca n b e s e a le d in a m p o u le s of q u a r tz o r h ig h -p u r i ty p o ly p ro p y le n e tub ing . P la s t ic ra b b its and p la s t ic sa m p le c o n ta in e rs a r e p a r t ic u la r ly advan tageous f o r s h o r t i r r a d ia t io n s , s in c e they do not a c q u ire a p p re c ia b le a m o u n ts of in d u ced ra d io a c tiv ity . H ow ever, in lo n g e r i r r a d ia t io n s m any p la s t ic s becom e b r i t t l e , te n d to d is in te g ra te , and th u s a r e not su ita b le c o n ta in e r m a te r ia ls .

F o r th e p r e p a ra t io n of iso to p e s of s h o r t h a l f - l i f e i t is s o m e tim e s c o n v en ien t to b o m b a rd re a d ily -s o lu b le s a l t s , f o r ex am p le n i t r a te s , r a th e r than th e e le m e n t i t s e l f . S o lu tions can a lso be i r r a d ia te d , if the to ta l e x p o su re is k e p t s h o r t , so th a t e x c e s s iv e g a s p r e s s u r e d o es no t b u ild up. P o ly e th y len e r a b b i t s m a y b e u s e d to c o n ta in s o lu tio n s an d r e m o te - c o n t r o l a p p a r a tu s i s a v a i la b le a t th is L a b o r a to ry f o r p u n c tu rin g th e r a b b i t s w ith a h y p o d e rm ic n e e d le an d th e n a p p ly in g su c tio n to r e m o v e th e s o lu t io n r a p id ly f r o m th e c o n ta in e r a f t e r th e i r r a d ia t io n .

D epend ing on th e p u r ity and n u c le a r p r o p e r t ie s , su ch a s c r o s s - s e c t io n of th e m a te r ia l i r ra d ia te d , the rad io iso to p e p roduced m ay o r m ay not re q u ire p u r if ic a tio n b e fo re u s e . S h o r t- l iv e d a c t iv i t ie s p ro d u ce d by s h o r t b o m b a rd m e n ts f re q u e n tly do not r e q u ir e p u r if ic a tio n . H ow ever, if r ig o ro u s sp e c if ic a tio n s a r e s e t on ra d io c h e m ic a l p u rity , e s se n tia lly a l l p re p a ra tio n s re q u ire t r e a tm e n t . Q u ite o ften a s in g le im p u rity p re d o m in a te s in a t r a c e r p r e p a r a tio n and the m ethod of p u r if ic a tio n is des igned to rem o v e the im p u rity s e le c tiv e ly . W e h a v e found io n -e x c h a n g e -c o lu m n te c h n iq u e s p a r t i c u la r ly u s e fu l f o r s u c h s e p a r a t i o n s an d tw o e x a m p le s , on e f o r c a tio n e x c h a n g e a n d on e f o r a n io n e x c h a n g e , a r e i l l u s t r a t e d in F ig s 3 an d 4.

In th e f i r s t e x a m p le a c a tio n ex ch an g e r e s in (Dowex 5 0 -X4) i s u se d to re m o v e 2. 7 -d A uiss f ro m 13. 6 -h P d 109 , p r e p a re d by i r r a d ia t in g p a llad iu m


(min)

Fig. 3

Separation o f 2 . 7 -d A u 198 from 1 3 .6 -h Pd109 by cation exchange (3 cm X 0 . 28 cm 2 co lum n, Dowex-50 x 4 , - 400 m esh, 25“C ) .

COLUMN VOLUMESI__________I___________ I :__________ I___________ I

О 5 Ю 15 20(min)

Fig. 4

Separation o f 2 .5 6 -h Ni66 from 1 0 .5 -m in C o eom(2j0 c m x 0 .2 8 c m 2 colum n D o w e x - lx lO ,200-400 m esh. 25°С )

m e ta l . A s m a l l am o u n t of go ld p r e s e n t in p a lla d iu m g iv e s r i s e to th e im p u r i ty . T h e s e p a r a t io n (F ig .3 ) i s b a s e d on th e o b s e rv a tio n [1] th a t AuC14

m a y b e a b s o rb e d by D ow ex 50 u n d e r c o n d itio n s w h e r e P d (II) (PdCl.*") i s w eak ly a d s o rb e d . T he am oun t of A u 198 p r e s e n t in th is p a r t i c u la r P d 109 p r e p a ra tio n w a s r e la t iv e ly low (£. 1%). H ow ever, s in c e A u 198 h a s a c o n s id e r


a b ly lo n g e r h a l f - l i f e th an P d 109 , i t s r e la t iv e am ount in c re a s e s rap id ly w ith t im e , an d n ee d f o r p u r if ic a tio n in c r e a s e s . T h e t im e r e q u ir e d to c o m p le te th e s e p a r a t io n i s l e s s th a n 5 m in .

A s e p a ra t io n of 10-m in Co60mfro m a 2 .5 6 -h Ni65 p re p a ra t io n i s show n in F i g . 4 . C obalt is a lm o s t in v a riab ly a s so c ia te d w ith n ic k e l and if the n ick e l t a r g e t i s n o t s p e c ia l ly p u r if ie d s ig n if ic a n t am o u n ts of c o b a lt a c t iv i t ie s a r e p ro d u c e d . By the u s e of an ion exchange te c h n iq u e s in HC1 m e d ia d e s c r ib e d e a r l i e r [2] , the Co im p u rity m ay be rem o v ed in l e s s than 5 m in by a d s o rp t io n , w h ile N i65 p a s s e s th ro u g h th e co lu m n u n a d s o rb e d . T h e С о (II) m a y b e e lu te d w ith HC1 so lu t io n s of lo w e r c o n c e n tra t io n .

W hen a t r a c e r p r e p a ra t io n c o n ta in s s e v e r a l im p u r i t ie s i t is g e n e ra lly m o r e a d v a n ta g e o u s , in c h ro m a to g ra p h ic m e th o d s , to a d s o r b th e d e s i r e d iso to p e ; by su b je c tin g it to bo th an a d so rp tio n and e lu tio n cy c le g r e a te r p u r i ty ca n be o b ta in ed . W hen a rad io iso to p e is to be iso la te d f ro m a cy c lo tro n ta r g e t , i t is no t only d e s ir a b le but a lm o s t m a n d a to ry th a t the t r a c e r be a d s o rb e d w h ile th e bu lk ta r g e t m a te r ia l is n o t. O th e rw ise the s iz e of the c o lum n and h en c e th e p u r if ic a tio n tim e m ay b eco m e e x c e s s iv e . A ty p ic a l i s o la t io n of a t r a c e r f ro m a c y c lo tro n ta r g e t m a te r ia l i s i l l u s t r a te d in F ig . 5.

Fig. 5

Separation o f Ga (III) from Zn (II) by cation exchange (Dowex 50-X 4, 200-400 m esh. 25°C)

A s m a ll c a tio n exchange co lum n w as u se d to a d s o rb Ga67 p re p a re d by p ro ton i r r a d ia t io n of a z in c ta r g e t . T h e p r o c e d u re is b a s e d on th e e a r l i e r o b s e r v a tio n s [1] th a t a t high HC1 conc e n tra tio n s Ga (III) is s tro n g ly a d so rb e d w hile z in c i s not a d s o rb e d . T he G a c a n be rem o v ed re a d ily a t an in te rm e d ia te HC1 c o n c e n tra t io n w h e re th e a d s o rp t io n fu n c tio n g o e s th ro u g h a m in im u m .

T h e t im e r e q u i r e d f o r a s e p a r a t io n of th is ty p e i s a b o u t 15 m in , i . e . so m e w h a t lo n g e r th a n th a t n e e d e d in th e o th e r i l l u s t r a t io n s g iven h e r e . By u s e o f s h o r t e r c o lu m n s an d h ig h e r flow r a t e s , s e p a r a t io n t im e co u ld be s u b s ta n t ia l ly d e c r e a s e d a lth o u g h w ith so m e s a c r i f ic e in y ie ld and , s o m e t im e s p u r i ty .


Ion ex ch an g e p r o c e d u re s a r e b ro a d ly a p p lic a b le to s e p a r a t io n s of th e type d e s c r ib e d , and an en o rm o u s body of in fo rm a tio n is p re s e n tly av a ila b le f ro m w h ich sp e c if ic is o la t io n s and p u r if ic a tio n s can be d ed u c ed . W hen s e p a r a t io n s a r e d e s ig n e d f o r s p e c if ic i s o to p e s , th e y c a n s o m e t im e s b e a c h ie v e d in a m a t t e r of m in u te s and , u n d e r s p e c ia l c i r c u m s t a n c e s , in s e c o n d s . In th e p r e s e n t s ta te of th e a r t c a r r i e r te c h n iq u e s a r e v e r y o f te n u se d a s re v e a le d by ev en a c u r s o r y e x a m in a tio n of a r e c e n t p u b lic a tio n by KUSAKA an d M EIN K E [3] w h ich s u m m a r iz e s a l a r g e n u m b e r o f s p e c ia l p r o c e d u r e s d e s ig n e d f o r r a p id r a d io c h e m ic a l s e p a r a t i o n s .

W e h a v e p u r s u e d d u r in g th e l a s t y e a r a so m e w h a t d if fe re n t o b je c tiv e , th e d ev e lo p m en t of a g e n e ra l s e p a ra tio n s sc h e m e w hich w ould be ap p lic a b le to e x t r e m e ly c o m p le x m ix tu r e s an d m ig h t e l im in a te , in m a n y c a s e s , th e n e e d f o r d e v e lo p m e n t of s p e c ia l p u rp o s e is o la t io n s c h e m e s . T o b e s u r e , th i s ca n on ly be a c h ie v e d by a s a c r i f i c e in th e sp e e d of s e p a r a t io n , b u t i t i s hoped th a t th e b ro a d sc o p e of a g e n e ra l m e th o d , co u p led w ith th e s im u lta n e o u s is o la t io n of a n u m b e r of p ro d u c ts , m ig h t c o m p e n sa te f o r th i s d i s a d v a n ta g e .

Som e of th e f e a tu re s w hich th e g e n e ra l ion exchange s e p a ra tio n s sch em e , now u n d e r d e v e lo p m e n t, w ill h a v e a r e show n in F ig . 6 w h ich r e p r e s e n t s a p r o c e d u r e f o r s e p a r a t in g u ra n iu m , n ep tu n iu m , p lu to n iu m an d th e f i s s io n p ro d u c ts in to tw o m a jo r g ro u p s , and a ls o f o r s p e c if ic a lly is o la tin g M o, T e and U, N p, P u . In th e p ro c e d u re [4] , th e i r r a d ia te d u ra n iu m ta r g e t i s d i s so lved in c o n c e n tra te d p e rc h lo r ic ac id to w hich v a r io u s m in e ra l a c id s (HNO^, H B r, H C l an d H F) a r e ad d e d . T h e s o lu t io n i s h e a te d to d r iv e off v o la t i le e le m e n ts (Ge, A s, Se, B r , K r, T e , Ru, Sn, Sb, I and Xe) w h ich c o m p r is e

ANIONEXCHANGE

_8MHCI-0.1rtiHF25 4MHCI-4/IÍHF 4Л7НС1 50° \M HCl

50° — —Mo Te Zn

CdPd

(Tc)(I)

V . 1

0.5«HCI-(/KHF

5 10 15- COLUMN VOLUMES

5 10 15COLUMN VOLUMES

Fig. 6

Separations schem e — iso la tion of M o, T e and U, Np, Pu


a " v o la ti le g ro u p " . T h e re m a in in g so lu tio n i s e v a p o ra te d , a d ju s te d to th e c o m p o s itio n 8 . 5 M НСЮ 4 - 0 . 5 M H C l - 0 .1 M H F , c h lo r in a te d an d ad d ed to a s m a l l co lu m n of D ow ex 50-X 4 c a tio n ex c h an g e r e s in . On e lu tio n w ith so lv e n t of the sa m e co m p o sitio n th e e le m e n ts sp lit in to an "a d so rb e d " group and a " n o n -a d s o rb e d 11 g roup .

T h e n o n -a d s o rb e d f ra c t io n is e v a p o ra te d , so lu tio n c o m p o s itio n is a d ju s te d to 8 M H C l - 0 .1 M H F , and th e so lu tio n i s p a s s e d in to a s m a ll c o lu m n of D ow ex 1 an io n ex ch an g e r e s in f o r f u r th e r s e p a ra t io n in to s m a l le r s u b -g ro u p s . E le m e n ts ad so rb e d in th is s te p can be b roken down into s m a lle r s u b - g ro u p s by a n u m b e r of e lu tin g te c h n iq u e s . F o r p r e s e n t p u r p o s e s w e s h a ll on ly c o n s id e r th e re m o v a l of M o " and Tei32 . T h e se f is s io n p ro d u c ts a r e s e le c t iv e ly e lu te d in r a d io c h e m ic a l ly - p u r e f r a c t i o n s w ith 4 M H C l - 4 M HF and 1 M H C l. O th e r f is s io n p ro d u c ts re m a in ad so rb e d on th e colum n but can be rem o v ed w ith su ita b le e lu e n ts .

T he g roup a d s o rb e d on the Dowex 50 -X4 co lum n is rem o v ed w ith 7 M HCL T h e re s u lt in g effluen t is ev a p o ra te d and th e com position ad ju s te d to 9 MHC1. B re a k d o w n of th e g ro u p i s a c h ie v e d by p a s s in g th e s o lu t io n in to a n o th e r s m a l l c o lu m n of D ow ex 1 an io n e x c h a n g e r e s in . A f te r w a sh in g th e n o n - a d so rb e d e le m e n ts (p rin c ip a lly r a r e e a r th s and s tro n tiu m ) th rough the colum n w ith 9 M H C l, th e co lum n is e lu ted se q u e n tia lly w ith 9 M H Cl - 0 .0 5 M N H 4I,4 M H Cl - 0 .1 M H F, and 0. 5 M HCl - 1 M H F . T he co rre sp o n d in g f ra c tio n s con ta in P u , Np and U a c tiv i tie s in ra d io c h e m ic a lly -p u re s ta te s except fo r the u ra n iu m f ra c t io n w hich c o n ta in s g a lliu m . F u r th e r s e p a ra tio n is r a r e ly r e q u ire d b e c a u s e g a lliu m o c c u r s a t v e ry low y ie ld . H ow ever, if d e s ire d , th e s e p a r a t io n of u ra n iu m an d g a lliu m ca n r e a d i ly be a c h ie v e d by f u r th e r ion exchange p ro c e s s in g .

T h e t im e r e q u ir e d to c a r r y ou t th e s e p a ra t io n and is o la tio n of Mo, T e , P u , Np, and U i s ab o u t fo u r h o u r s . T h is d o es no t a p p e a r an u n re a so n a b ly long tim e f o r iso la tio n s of th e se re la t iv e ly lo n g -liv e d f is s io n p ro d u c ts . The sc h em e h a s the ad d itio n a l advan tage th a t s e v e ra l sa m p le s can be run s im u lta n e o u s ly by the sa m e o p e r a to r s in c e m o s t of the tim e is sp en t in d ev e lo p in g th e c o lu m n s r a t h e r th a n in o p e r a t io n s r e q u i r in g c o n s ta n t a t te n t io n .

2 . T Y P IC A L STU D IES W IT H S H O R T -L IV E D R A D IO ISO T O PE S

2 . 1 . S o lu b ili ty m e a s u r e m e n t s - p a c k e d -b e d te c h n iq u e sT h e s tu d y of tw o -p h a se e q u il ib r ia is v e ry m uch s im p lif ie d th ro u g h the

u s e of t r a c e r s a s we have d is c u s se d a t so m e len g th in an e a r l i e r p a p e r [5] . O f th e tW o -p h a se e q u i l ib r ia , th e s im p le s t , th e o r e t ic a l l y , a r e s o lu b i l i ty m e a s u r e m e n ts , and a w e a lth of in fo rm a tio n r e g a rd in g so lu tio n p r o p e r t ie s m a y be o b ta in e d f ro m s o lu b ili ty s tu d ie s . W e h a v e p o in te d ou t e a r l i e r th a t w ith a "p a c k e d -b e d " tech n iq u e , m e a s u re m e n ts can be c a r r ie d out e x tre m e ly ra p id ly ; th is m e th o d th u s a p p e a r s th e te c h n iq u e of c h o ic e w hen s h o r t liv e d t r a c e r s a r e u se d . S ince p ac k ed -b ed tech n iq u es fo r so lu b ility m e a s u re m e n ts a r e no t p a r t i c u la r ly w id e ly -k n o w n o r u s e d , w e s h a l l g iv e a ty p ic a l a p p lic a tio n h e r e and r e f e r th e r e a d e r to th e e a r l i e r p a p e r fo r e x p e r im e n ta l d e ta i l s .

T h e so lu b i l i ty of la n th a n u m f lu o r id e w a s d e te r m in e d in a v a r i e ty of H F -co n ta in in g so lu tio n s u s in g 4 0 -h L a 14U a s t r a c e r s . The lan thanum flu o rid e


w as p re c ip i ta te d in th e p r e s e n c e of a known am oun t of t r a c e r ; th e m a te r ia l w as then d r ie d and h ea ted a t 400°C fo r 18 h . T he anhydrous LaF 3 w as fo rm ed ; X - r a y a n a ly s is show ed i t to h av e th e h ex a g o n a l s t r u c tu r e c h a r a c t e r i s t i c of th e u n h y d ra te d L aF 3 [6 ] and th a t i ts s t r u c tu re d id not change a f te r the so lid had been co n ta c te d s e v e r a l h o u rs w ith the so lu tio n s of in te r e s t . S o lu b ilitie s w e re d e te rm in e d by p a s s in g v a r io u s so lu tio n s th ro u g h a bed of th e s e c r y s t a l s . F lo w -ra te s w e re v a r ie d to a s s u r e th a t e q u ilib r iu m had b ee n r e a c h e d . F r o m th e s te a d y - s ta te coun ting r a te of th e e ff lu en t so lu tio n s and th e known co u n t- to -w e ig h t r a t io of th e so lid , s o lu b i l i t ie s w e re co m p u ted . -

T h e r e s u l t s of a s e r i e s of m e a s u r e m e n ts a t 50° an d 70°C w ith L a F e in HC1-HC104 m ix tu re s of c o n s ta n t to ta l m o la r i ty (МНС1 + МНСЮ4 = 8 . 9 , M is m o le s p e r l i t e r o f so lu tio n ) c o n ta in in g of 0 . 1 M H F a r e show n in F ig . 7, a p lo t of th e log of th s so lu b ility v e r s u s th e f r a c t io n of FHC104 in th e so lu tio n , (FHCio4 = МнсюУ (М НС1 + MHC104 ))• T h e so lu b i l i ty d e c r e a s e s m a rk e d ly w ith in c re a s in g FHC104 a * bo th t e m p e r a tu r e s .

Fig. 7

S o lub ility o f LaFj in 8.9 M HC104 -HC1 m ixtures a t constant 0 .102 M HF

M e a su re m e n ts of the so lu b ility of L a F 3 w e re a lso c a r r ie d out w ith 11.0m (8 .9 M) HC1 so lu t io n s a s a fu n c tio n of m H F (fro m m = 0.06 to m = 0 .1 2 ) , w h e re m r e p r e s e n t s m o le s p e r 1000 g of w a te r . T h e s o lu b i l i t i e s v a r ie d a p p ro x im a te ly w ith the th ird pow er of th e HF c o n c en tra tio n a s expected fro m the equation

L a F 3 + 3 H+?=iLa+3 + 3 H F (1)

F o r th e 1 1 .0 m HC1 so lu tio n , th e v a lu e of th e a p p a re n t s o lu b i l i ty p ro d u c t

K m = K /G = m Lam 3F/ m 3

w h e re G i s th e a p p ro p r ia te a c tiv ity c o e ff ic ie n t p ro d u c t, w as co m p u ted . Кш


w as found to be 1 .6 X 10-H, 1 .1 X 10-ю , and 4 .6 X 10-ю a t 25, 50 and 70°C, r e s p e c t iv e ly . A c c o rd in g to F ig . 7, Kmd e c r e a s e s on th e a d d itio n of H C104

and in с . 9 M H C I-H C IO 4 m ix tu re s w ith F HC104 = 0 . 5, Km is a p p ro x im a te ly an o r d e r of m ag n itu d e s m a l le r than in p u re H Cl so lu tio n s of th e sa m e co n c e n tra tio n .

T o o u r know ledge no so lu b ili ty d a ta on la n th a n u m f lu o r id e h a v e b ee n p u b lis h e d f o r s o lu tio n s of v e r y h ig h io n ic s t r e n g th . I t m a y be of in te r e s t , h o w e v e r, to n o te th a t o u r v a lu e f o r th e so lu b ility p ro d u c t in 1 1 .0 m H Cl a t 25°C i s so m ew h at lo w e r th a n th e v a lu e Km = 7. 5 X 10" 10 com puted f ro m d ata g iven by KURY [ 6] who m e a s u re d so lu b ility in 0 . 5 M p e rc h lo ra te so lu tions w ith a m a te r i a l f o r w h ich h e g iv e s th e c o m p o s it io n L a F 3 • 1 /2 H 2 0 .

M O LAR ITY H3B 0 j ADDED

Fig. 8

Solub ility o f LaF3 a t 25°C in 9 M HCl - 0 . 1 M HF solutions as a function o f M H3BOs

F ro m the te m p e ra tu re co e ffic ien t of the so lu b ility of LaF 3 , the ap p aren t h e a t of r e a c t io n ДН* f o r r e a c t io n 1 w as found to be c . -16 k c a l /m o le ; the co rre sp o n d in g v a lu es fo r AF* and AS* a t 25°C a r e 11 k c a l/m o le and 92 E . U . re sp e c tiv e ly .

T o i l l u s t r a t e f u r th e r th e v e r s a t i l i ty of s o lu b i l i ty m e a s u r e m e n ts w ith sh o r t- l iv e d t r a c e r s , we r e p o r t on the so iu b ility of LaF3 in 9 M HCl so lu tions co n ta in in g v a r ia b le am o u n ts of b o r ic a c id an d a c o n s ta n t am o u n t (0.1 M) of H F . T h e d a ta a r e s u m m a r iz e d in F ig . 8 w h e re i t m a y be s e e n th a t s o lu b i l i ty i n c r e a s e s m a rk e d ly on th e a d d itio n of H 3 B 0 3 . W hile th e o r ig in a l p u rp o s e of th e s e m e a s u r e m e n ts w as to d e te rm in e th e am oun t of b o r ic ac id r e q u ire d in su ch so lu tio n s to g ive re a s o n a b le so lu b ility of L a F 3 , i t should be r e c o g n iz e d th a t so lu b i l i ty d a ta of th is ty p e ca n be u t i l iz e d f o r e lu c id a tio n of th e c o m p le x in g r e a c t io n s , "the in c r e a s e in s o lu b i l i ty of L a F 3 i s p r e s u m a b ly c a u se d by f lu o r id e com plex ing of H 3BC>3 . T he o b se rv e d so lu b ility along w ith th e know n so lu b i lity p ro d u c t, th e to ta l f lu o r id e c o n c e n tra tio n and th e to ta l


b o ro n c o n c e n tra t io n , p e r m i t s c o m p u ta tio n of th e a v e r a g e n u m b e r , ñ , of f lu o r id e io n s a t ta c h e d to b o ro n . In 9 M H C l - 0 . 1 0 M H F , П w a s fo u n d to d e c r e a s e f ro m 3. 65 to 1. 54 a s th e b o r ic a c id c o n c e n tra tio n in c re a s e d f ro m0 .0 2 0 to 0 .2 0 1 m o le s p e r l i t e r . T h e c o r re sp o n d in g " f r e e " H F c o n c e n tra tio n s d e c re a s e d rap id ly f ro m 0 .1 0 M fo r МНзВОз = 0 to £ . 0 .0 1 M a t Mh, bo, =0 .0 5 . F u r th e r in c re a s e of MH Bq to 0. 20 lo w ere d th e f r e e HF c o n c e n tra tio n only to about 5 X 10-3 m , in a c c o rd a n c e w ith th e ex p ected b u ffe rin g ac tio n of su ch a sy s te m .2 . 2 . A d so rp tio n s tu d ie s w ith ion exchange m a te r ia ls

We have u se d ra d io iso to p e s e x ten s iv e ly f o r s y s te m a tic and c o m p a ra tiv e s tu d ie s of the ion exchange b eh a v io u r of the e le m e n ts in a v a r ie ty of m ed ia , p a r t i c u l a r l y co m m o n m in e r a l a c id s , f o r a n u m b e r of y e a r s [7] . T h e s e s tu d ie s y ie ld in fo rm a tio n on co m p lex in g b e h a v io u r of th e e le m e n ts [ 8] , on p r o p e r t i e s of th e io n ex c h a n g e m a te r i a l s [5] , an d s e r v e a s th e b a s i s f o r m a n y s e p a r a t io n s m e th o d s .

A n a ly ses of re la t iv e ly c o m p lic a te d m ix tu re s can o ften be s im p lif ie d by u s in g so m e t r a c e r s h av in g s h o r t - h a l f - l iv e s ; by e x a m in in g th e d ec ay r a te s of, f o r e x a m p le , e lu tio n b a n d s , so m e e le m e n ts m ay be r a p id ly id e n tif ie d . S om e of th e in c o n v e n ie n c e a t te n d in g th e u s e of s h o r t - l iv e d is o to p e s in e x p e r im e n ts of th is ty p e is av o id ed by s e le c tin g a p p ro p r ia te p a r e n t-d a u g h te r p a i r s . A ty p ic a l exam ple of the u se of two such p a i r s , 2 .6 -d M o " - 6 -h T caam and 11 8 -d S n i13 - 1 0 4 -m in Inii3ni i s show n in F ig . 9 . A lo n g - l iv e d

Fig. 9

Sim ultaneous study of e lem ents with d ifferen t decay characteristics (Dowex 1 X 4 , 50°C)

----------------- In it ia l counting ra te .. . . ----------- c.R . a fte r 6 h.

t r a c e r , 4 7 -d H g203 , w as a lso u se d . T he m ix tu re of t r a c e r s in 4 M HCl w as added to an an io n ex ch an g e c o lu m n . T he co lu m n w as e lu te d w ith 4 M H C l -0 . 05 M H F an d th e n w ith c h lo r in a te d 4 M HNO 3 - 1 M H C l - 0 .2 M H F . T h e e f f lu e n t f r a c t io n s w e r e c o u n ted im m e d ia te ly a f t e r c o l le c t io n (h eav y l in e s in F ig . 9) an d a g a in a f te r s ix h o u r s (d a sh e d l in e s ) . T h e e lu tio n p o s i t io n s of th e e le m e n ts w e re d i r e c t ly a s c e r ta in e d f ro m d e c a y - r a te c o n s id e ra t io n s . T he f i r s t band d ecay ed to a p p ro x im a te ly 10% of i t s in it ia l v a lu e , th u s id e n tify in g it a s 1 0 4 -m in ln 113m . T h e seco n d band d ec ay e d a p p ro x im a te ly 50% in


th is p e r io d , c h a r a c t e r i s t i c of 6 -h T c 99m . T h e b an d s f o r th e p a re n t a c t iv i t ie s , M o " and S niis j th e second and fo u rth bands in the fig u re , w ere id e n tif ie d th ro u g h the c o r re sp o n d in g grow th of the d au g h te r a c tiv i tie s . T he coun ting r a te of the la s t e lu tion band re m a in e d e s se n tia lly unchanged, thus id e n tify ing it a s the 47 -d H g203 .2 .3 . D iffusion s tu d ie s

A lm o s t s in c e th e d is c o v e r y of r a d io a c t iv i ty r a d io is o to p e s h a v e b ee n u se d fo r th e in v e stig a tio n of d iffusion phenom ena. The radon em anation te c h n iq u es, o r ig in a ted by HAHN [9, 10] a r e c la s s ic a l exam ples of a r a th e r sub tle u s e of r a d io a c t iv i ty in d if fu s io n s tu d ie s . A s r a d io is o to p e s b e c a m e m o r e w idely av a ila b le they found in c re a s in g app lica tio n in diffusion m e a su re m e n ts . S om e of the n u m e ro u s t r a c e r te c h n iq u e s developed fo r such p u rp o se s , w ith g a s e s , liq u id s and so lid s , have been rev iew ed by WANG [ 1 1 ] .

In s tu d ie s of d if fu s io n in liq u id s an d o rg a n ic an d in o rg a n ic io n e x c h a n g e r s , w e h a v e so u g h t to u s e o r d e v is e t r a c e r m e th o d s w h ich a r e i n t r i n s i c a l l y v e r y r a p id w h ile s t i l l r e ta in in g r e a s o n a b le p r e c is io n . S uch a goal is d e s ira b le even w ith t r a c e r s of long h a l f - l iv e s . W ith s h o r t- l iv e d is o to p e s , r a p id m e th o d s a r e a p r im a ry r e q u ir e m e n t s in c e , of c o u r s e , th e m e a s u r e m e n ts n ee d to be c o m p le te d in t im e s c o m p a ra b le w ith th e l if e t im e of th e t r a c e r .

W e h av e found an a d a p ta tio n of th e " sh a llo w -b e d " te ch n iq u e a s a t i s f a c to ry m ethod fo r the d e te rm in a tio n of d iffusion co e ffic ie n ts in ion ex ch an g e rs ( p a r t ic le d iffu s io n ) an d a so m e w h a t s im i l a r te c h n iq u e , th e " f r i t m e th o d " f o r m e a s u re m e n t of d iffu s io n in liq u id s ; bo th m e th o d s a r e d is c u s s e d in th e n ex t s e c tio n s .2 .3 .1 . P a r t ic le d iffu s io n — sh a llo w -b e d te ch n iq u e

F o r m e a s u re m e n t of d iffu s io n in ion e x c h a n g e rs , a sh a llo w -b e d te c h n iq u e w a s in tro d u c e d by Du DO M AIN E, SWAIN an d HOUGEN [12] . T h e m ethod w as m od ified by BOYD, ADAMSON and MYERS [13] . T h e se a u th o rs fo rc e d so lu tion c o n ta in in g tra c e r th rough a shallow bed of ion e x c h an g e r,m e asu re d th e tim e of co n ta c t and, a f te r w ash in g and d ry in g th e bed , d e te rm in e d th e am o u n t of t r a c e r ta k e n u p . F r o m th e s e d a ta th e y c o m p u te d d if fu s io n c o e f f ic ie n ts .

T h e te c h n iq u e th a t w e u s e s e e m s so m e w h a t s im p le r an d m o r e r a p id . T h e t r a c e r is f i r s t e q u i l ib r a te d w ith r e s in b e a d s of u n ifo rm r a d iu s R . A v e ry sha llow bed, u su a lly abou t 1 m m in dep th , is th en p re p a re d ; the beads a r e s u p p o r te d in a tu b e on a f in e m e s h p la tin u m g a u z e , on g la s s w o o l o r

Fig. 10

Rapid m easurem ent of diffusion ra tes. T racer in (A) shallow b ed , (B) porous fr it


f r i t s , o r , in th e p r e s e n c e of H F , on a p o ro u s T eflo n p lug . T he bed is c o n tin u o u s ly v iew ed by a s c in t i l la t io n c o u n te r th ro u g h a s l i t in a le a d s h ie ld .

A f te r th e in i t ia l co u n tin g r a t e i s e s ta b l is h e d th e bed i s ra p id ly w ash e d w ith so lu tio n of th e s a m e c o m p o s itio n a s th a t u se d in th e e q u i l ib ra tio n but w ith o u t t r a c e r . T h e c o u n tin g r a t e of th e bed d u r in g e lu tio n is e s ta b l is h e d a s a function of t im e . T he ex p e r im e n ta l a r ra n g e m e n t is i l lu s tra te d in F igüO . F lu c tu a tio n s in te m p e ra tu re a r e n eg lig ib le if th e te m p e ra tu re of the inflow - ing so lu tio n is kep t co n s ta n t. T e m p e ra tu re can a lso be co n tro lled by ja c k e ting th e bed and flow ing a th e rm o s ta te d liq u id th ro u g h i t . T h is a r ra n g e m e n t, h o w e v e r, is u s u a lly l e s s e f f ic ie n t, s in c e th e d is ta n c e b e tw e en th e c o u n te r an d th e bed i s in c re a s e d by th e ja c k e t .

A t ra p id flow '-ra tes, t r a c e r is flu sh ed aw ay f ro m the p a r t ic le s a s r a p id ly a s it d if fu s e s f r o m th e m ; u n d e r th e s e c o n d it io n s , th e r a t e of r e m o v a l can be a s su m e d to be c o n tro lle d by d iffu s ion , c h a r a c te r iz e d by th e d iffusion c o e f f ic ie n t , 3 ), of t r a c e r w ith in th e p a r t i c l e s . A c c o rd in g to th e d if fu s io n th e o ry f o r s p h e r ic a l p a r t i c l e s of r a d iu s , R, th e c o n c e n tra tio n , C , of t r a c e r in th e sh a llo w bed sh o u ld d e c r e a s e e x p o n e n tia lly w ith t im e , t , a c c o rd in g to th e e q u a tio n

w h e re C0 i s th e in i t ia l c o n c e n tra tio n of t r a c e r in th e bed and Xr = 2>ir2/ R 2 .A fte r an in i t ia l t r a n s ie n t e ffec t a s s o c ia te d w ith th e decay of h ig h e r d if

fu sio n m o d es h a s d ied o u t.te rm s f o r n> 1 becom e u n im p o rta n t and С d e c re a s e s a s e '^ t1 [14] . T he d iffusion co e ffic ien t, 3), m ay then be d e te rm in e d d ire c tly f r o m th e s lo p e (Xr ) in th e l i n e a r p o r t io n of a p lo t of lo g С v e r s u s t im e .

In e x p e r im e n ts w h e re s h o r t- l iv e d t r a c e r s a r e u se d , s ig n if ic a n t r a d io a c tiv e d e c a y of t r a c e r m a y o c c u r d u r in g e lu tio n and th e s lo p e , d lo g C / d t

(2)n = 1

0 2 3 4 5(min)

6 7 8

Fig. 11

D eterm ina tion of diffusion ra te o f B r ' in aqueous solution and ion exchange resin beads (3 6 -h Br81 , supporting e lec tro ly te 1 M LiCl).


b ec o m e s equa l to Xr + X, w h ere X i s the ra d io a c tiv e decay c o n s tan t. C o r r e c tio n f o r d e c a y is s im p ly m a d e by s u b tr a c t io n o f th e d e c a y c o n s ta n t of the' t r a c e r f r o m th e o b s e rv e d s lo p e .

A typicd.1 d if fu s io n m e a s u r e m e n t w ith a sh a llo w b e d i s show n by th e lo w e r c u rv e in F ig . 11 . F o r th is e x p e r im e n t u n ifo rm b e a d s of an an ion e x ch an g e r e s in (Dow ex 21 K) w e re e q u il ib ra te d f o r s e v e r a l h o u r s w ith a 1 M L iC l so lu tio n c o n ta in in g 3 6 -h B r 82 . д sh a llo w b ed of th e b e a d s w a s th e n e lu te d w ith 1 M L iC l a t 25°C a t a f lo w -ra te of 5 c m / s . T h e o b s e rv e d s lo p e of a p lo t of lo g С v e r s u s t im e w a s fo u n d to b e 0 .0 1 3 0 s ' 1. T h e v a lu e

^B r = 1 .5 2 X 10"6 c m 2/ s w a s c o m p u te d d i r e c t ly f r o m th e o b s e rv e d s lo p e s in c e , in th is e x p e r im e n t , th e d e c a y c o r r e c t io n f o r 3 6 -h B r 8 2 Wa s n e g l i g ib le (X < 10"5 s_1).2 . 3 . 2 L iq u id d if fu s io n — p o r o u s - f r i t te c h n iq u e

T he p o r o u s - f r i t m ethod is co n cep tu a lly s im i la r to the sh a llo w -b ed te c h n iq u e . In s tea d of e q u ilib ra tin g a sa m p le of r e s in w ith t r a c e r so lu tion , a slab of p o ro u s m a te r ia l is s a tu ra te d w ith the so lu tion . The d iffusion r a te is d e te rm in ed by pum ping so lu tio n p a s t the s la b in a m a n n e r ana logous to the sha llow - bed m ethod .

T he p o r o u s - f r i t m ethod w as ap p a re n tly f i r s t d e s c r ib e d by W ALL.GRIEGER an d C H IL D E R S 115J w ho d e v is e d i t f o r th e m e a s u r e m e n t o f d if fu s io n r a t e s of s lo w ly d if fu s in g o rg a n ic p o ly m e rs . I t is r e a d i ly a d a p ta b le f o r u s e w ith t r a c e r s ; w ith th in f r i t s it is an exceed ing ly s im p le and ra p id tech n iq u e . B e c a u s e of th e s h o r t , th ough to r tu o u s , d if fu s io n p a th in th e f r i t s w e h a v e used (as th in a s 0 . 05 cm ), th e m ethod is c o n s id e rab ly m o ré rap id than m any o th e r te c h n iq u e s , su c h a s th e c a p i l la r y m e th o d o r ig in a te d by ANDERSON and SADDINGTON [16] in w h ich c a p i l la r y tu b e s tw o o r m o re c e n t im e te r s lo n g a r e g e n e ra l ly em p lo y ed .

In th e f r i t m e th o d , so lu tio n c o n ta in in g th e t r a c e r i s e q u i l ib ra te d w ith a s m a ll p ô ro u s f r i t , u su a lly u ng lazed p o rc e la in . A fte r i t h a s been u n ifo rm ly s a tu r a te d , th e f r i t i s s u p p o r te d v e r t i c a l ly in a c o n s t r i c te d tu b e (F ig . 10) th ro u g h w h ich a so lu tio n n o t c o n ta in in g t r a c e r , b u t o th e rw is e of th e s a m e c o m p o s itio n , i s p u m p e d . T e m p e r a tu r e c o n t ro l c a n b e a c h ie v e d a s in th e sh a llo w -b e d m e th o d . T he coun ting r a te of th e s la b is e s ta b lish e d a s a fu n c t io n of t im e w ith a s h ie ld e d c o u n te r , v ie w in g th e s la b th ro u g h a s l i t .

F ro m th e l in e a r p o r tio n of a p lo t of th e lo g of th e coun ting r a te ( c o r re c te d f o r b ac k g ro u n d ) of th e f r i t a s a fu n c tio n of t im e , a n e x p o n e n tia l r a t e c o n s ta n t, Xr, can be e s ta b lish e d in e s se n tia lly the sam e m a n n er a s in the sh a llo w - b ed m e th o d . A ty p ic a l e x p e r im e n t f o r th e d if fu s io n of t r a c e r B r 82 f ro m a th in s la b i s show n in F ig . 11. T h e d if fu s io n c o e ff ic ie n t i s p r o p o r t io n a l to Xr , c o r r e c te d f o r d ec ay of th e t r a c e r . T o o b ta in a b s o lu te d iffu s io n c o e ff ic ie n ts r a t h e r th a n r e la t iv e o n e s , th e f r i t s a r e c a l ib r a te d w ith a m a te r i a l of know n d iffu s io n c o e f f ic ie n t .

A c c o rd in g .to d if fu s io n th e o ry , d if fu s io n c o e f f ic ie n ts m a y be o b ta in ed f ro m Xr even if the f r i t s a r e i r r e g u la r in -sh ap e [17] . H ow ever, th e g r e a te r th e d e p a r tu re of th e f r i t f ro m s im p le fo rm s (fo r ex am p le s p h e r ic a l o r in f in ite s la b g eo m etry ) , th e lo n g e r w ill be th e tim e b e fo re the d e s ire d exponent i a l is e s ta b lish e d .

W ith th in f r i t s i t i s im p o r ta n t to d e m o n s tr a te th a t th e r a t e of d iffu s io n f o r a g iven s y s te m is independen t of f lo w -ra te . We have n o rm a lly u se d flow


r a t e s s e v e r a l o r d e r s of m a g n itu d e l a r g e r th a n th e r a t e of d if fu s io n ou t of th e f r i t s to e n s u re th a t s ig n ific a n t b oundary la y e r e ffe c ts do not a r i s e . W ith f r i t s ab o u t 1 -c r ii long , 8 -m m w id e , an d a s th in a s 0 . 0 5 c m , no c h a n g e in th e ex p o n en tia l r a te of re m o v a l of th e t r a c e r w as o b se rv e d , even w ith ,r e la tiv e ly v is c o u s so lu tio n s , w hen f lo w -ra te w as v a r ie d betw een 10 and 20 cm /s.

T y p ic a l d iffusion r e s u l t s ob ta ined by the f r i t m ethod a r e shown in F ig .12 in w h ich d iffu s io n c o e f f ic ie n ts of t r a c e r b ro m id e ( B r 82 ) in H C l, L iC l, and b e n z y ltr im e th y la m m o n iu m c h lo r id e (BC1) s o lu t io n s a r e g iv e n f o r a w id e ra n g e of c o n c e n tra tio n . F r i t s ran g in g in th ic k n e s s f ro m about 0 .0 5 t o 0.1 cm w e re u se d and each f r i t w as c a lib ra te d b e fo re u se w ith an e le c tro ly te (NaBr) of know n d if fu s io n c o e f f ic ie n t . T h e t im e r e q u ir e d p e r in d iv id u a l m e a s u r e m e n t ra n g e d f ro m ab o u t a m in u te to s e v e r a l h o u r s d ep en d in g on th e n a tu re and c o n c e n tra tio n of e le c t ro ly te .

Fig. 12

Diffusion coeffic ien ts of tra c e brom ide (Br*2) in various e lectro ly tes.

--------- a Br П/Чо

A lthough d iffusion c o e f f i c i e n t s , , v a ry f ro m c . 2 X 10-5 to 10"7 cm 2/s , i t i s in te r e s t in g to n o te th a t th e p ro d u c t 2 >Br тч/щ, w h e re r)/rj0 i s th e r e l a t iv e v is c o s i ty of s o lu tio n c o m p a re d to w a te r , i s e s s e n t i a l l y in v a r ia n t a s show n in F ig . 12 . T h u s i t m a y b e c o n c lu d e d th a t d if fu s io n of b r o m id e in th e s e d i s s im i l a r e l e c t r o ly te so lu t io n s d e p e n d s p r im a r i l y on th e v is c o s i ty o f th e m e d iu m . T h is m ay a p p e a r s u r p r i s in g , p a r t i c u la r ly s in c e one of th e e l e c t r o ly te s (BC1) h a s a r a t h e r l a r g e v o lu m e .

T he p u rp o se of th e s e and s im i la r d iffu s ion m e a s u re m e n ts , p a r t ic u la r ly th o s e w ith b e n z y ltr im e th y la m m o n iu m c h lo r id e so lu tio n s , w a s to d e te rm in e how f a r c o n c e n tra te d e le c tro ly te so lu tio n s can s e r v e a s m o d e ls f o r ion e x c h a n g e rs . T he q u a te rn a ry am in e w as chosen b ec au se it re s e m b le s the s t r u c tu r a l u n it of an ion ex c h an g e rs , of th e D o w ex -1 ty p e . A p re lim in a ry r e p o r t of th e im p l ic a t io n s of su c h d if fu s io n m e a s u r e m e n ts to d if fu s io n in a n io n e x


c h a n g e rs h a s b ee n p u b lish ed e a r l i e r [1 8 ]; w h ile d e ta ile d d is c u s s io n of th is a s p e c t o f th e d if fu s io n m e a s u r e m e n ts is b ey o n d th e s c o p e an d p u rp o s e of th is p a p e r , a b r i e f s u m m a r y m a y b e of i n t e r e s t .

I t a p p e a r s th a t d if fu s io n p r o p e r t i e s o f a n io n e x c h a n g e r e s i n s c lo s e ly p a r a l le l th o se of (co n cen tra ted ) BC1 so lu tio n s of s im ila r w a te r con ten t. E ven u n d e r c o n d itio n s w h e re th e r e s in s ta k e up c o n s id e ra b le am o u n ts of su p p o r tin g e le c tro ly te — a s , f o r e x a m p le , w hen th e y a r e e q u i l ib ra te d w ith c o n c e n t r a t e d H C l o r L iC l s o lu t io n s — th e p a r a l l e l p e r s i s t s p ro v id e d c o m p a r is o n i s m a d e w ith BC1 s o lu t io n s of s im i l a r e l e c t r o ly te an d w a te r c o m p o s it io n . T h e poly e le c tro ly te n a tu re of th e e x c h a n g e rs th u s s e e m s of only m in o r im p o r ta n c e . W ith r e s p e c t to t r a n s p o r t p ro p e r t ie s , i t a p p e a rs th a t one can affix to th e e x c h a n g e rs a h y p o th e tic a l v is c o s ity w hich i s in tim a te ly r e la te d to the a c tu a l v i s c o s i t i e s o b s e rv e d in th e s e m o d e l e l e c t ro ly te so lu t io n s . In o th e r s tu d ie s of e q u ilib riu m p ro p e r t ie s , a s im i la r conc lusion w as draw n reg a rd in g s e le c t iv i t ie s .2 .4 . Som e m ilk in g tech n iq u es

In m ilk in g m e th o d s a r e la t iv e ly s h o r t- l iv e d d a u g h te r is s e p a ra te d f ro m a lo n g -liv e d p a re n t w hich is u su a lly r e ta in e d in a so lid o r liq u id p h ase . The p h ase con ta in ing th e p a re n t m ay th u s s e rv e a s a so u rc e f ro m w hich d augh ter a c tiv i ty can be re m o v e d p e r io d ic a lly . M ilk ing te ch n iq u e s a r e not only u se fu l in e s ta b l is h in g g en e tic re la t io n s h ip s in n u c le a r d ecay sc h e m e s but can a lso be u se d to p ro v id e s o u rc e s of ra p id ly -d e ca y in g ac tiv ity f o r a v a r ie ty of p u r p o s e s , a s d ic u s s e d in o th e r p a p e r s o f th i s S e m in a r ; th e y f in d a p p l ic a tio n in d iffusion s tu d ie s and a r e an ex c e llen t m ethod fo r c h a ra c te r iz in g the n a tu re of the m a te r ia l in w hich th e p a re n t is held .

In a s e n s e , th e ion ex ch an g e s e p a ra t io n show n in F ig . 9 i l l u s t r a t e s th e "m ilk ing" of 1 04 -m in In i13m f ro m Sn113 ad so rb e d by th e ex ch an g e r. The p ro n o u n ced " ta i l in g " of th e e lu tio n b and of ln 113m r e s u l t s f r o m th e co n tin u in g p ro d u c tio n of th is d a u g h te r e lu tio n ; if e lu tio n had b ee n s to p p ed a few h o u rs to a llo w b u ild u p of th e d a u g h te r , a b u r s t o f l n 113m a c t iv i ty w o u ld h a v e b ee n o b s e rv e d in th e e f f lu e n t on r e s u m in g e lu tio n .

C h ro m a to g ra p h ic te c h n iq u e s a r e id e a lly su ite d f o r m ilk in g s e p a ra tio n s s in c e th ey a r e c a p a b le of y ie ld in g th e d a u g h te r in a s ta te of e x tre m e ly h igh p u r i ty , p a r t i c u la r ly a f t e r r e p e a te d m ilk in g s . T h e m e th o d s a r e r a p id an d s im p le . A few ty p ic a l e x a m p le s in vo lv ing s e p a ra t io n of d a u g h te r a c t iv i t ie s f ro m p a re n ts a d s o rb e d on s m a ll ion exchange co lu m n s ( 3 c m X 0.25 cm^) a r e show n in F ig . 13. In th e f i r s t ex am p le , 6 -h T c 99m is rem o v e d w ith 2 MHNO3

f ro m i t s p a re n t, Mo99 , a d s o rb e d on h y d ro u s z irc o n iu m ox ide [19] ; in th e seco n d , 1 0 4 -m in I n i13m is s e p a r a te d w ith 1 M HF - 0 .1 M H Cl f ro m i t s p a re n t, S n ii3, a d so rb e d on an an ion exchange r e s in [7(b)] ; in the th ird exam ple , 17. 6 -m in P r iw i s m ilk e d w ith 6 M HNO3 - 0 .1 M Н 3ВГО3 f ro m an an ion exchange co lum n on w hich th e p a re n t C e 144, a s Ce(IV), is s tro n g ly a d so rb e d [7(c)] .

In th e s e e x a m p le s it m ay be n o te d th a t th e in i t ia l h ig h coun ting r a te is fo llow ed by a s te a d y - s ta te e lu tio n r a t e of d a u g h te r w h ich i s d ep en d en t p r i m a r i ly on th e h a l f - l i f e of th e d a u g h te r an d th e c o n ta c t t im e of th e b ed w ith th e m o b ile liq u id p h a se . In e x p e r im e n ts involv ing v e ry s h o r t- l iv e d d au g h te r a c t iv i t ie s th e c o n ta c t t im e sh o u ld , of c o u r s e , b e of th e s a m e o r d e r o r l e s s th a n th e h a l f - l i f e of d a u g h te r if a r e a s o n a b le y ie ld f o r th e s e p a ra t io n i s to


COLUMN VOLUMES OF EFFLUENT

Fig. 13

Separation of daughter ac tiv itie s by "m ilk ing". (F low -ra te с . 0 .5 c m /m in ) .

be o b ta in ed . T h u s , w ith a c t iv i t ie s hav ing h a l f - l iv e s of th e o r d e r of m in u te s o r se c o n d s , f lo w -ra te s m u s t be of the o r d e r of m in u te s o r se co n d s p e r c o lu m n v o lu m e . In th e l im itin g c a s e of e x tre m e ly r a p id e lu tio n w h e re co n tac t t im e m ay be c o n s id e re d n e g lig ib le , th e r a te a t w h ich d au g h te r a c tiv ity a p p e a r s in th e e ff lu en t i s d ep e n d en t on th e r a te of d e c a y of th e d a u g h te r , the d iffu s io n co e ffic ie n t of th e d a u g h te r in th e ex c h an g e r, and th e d im e n s io n s of th e ex c h a n g e r p a r t i c le s .

T h e fu n d a m e n ta l re la t io n s h ip s w h ich d e te rm in e th e s e p a ra b i l i ty w h ich can be ach iev ed u n d e r ra p id -e lu tio n cond itions w ith p a re n t-d a u g h te r sy s te m s w e re d is c u s se d e a r l i e r [14] ; eq u a tio n s w e re d e r iv e d f o r s p h e r ic a l p a r t ic le s f o r co m p u tin g th e y ie ld , d e fin e d a s th e f r a c t io n of d a u g h te r a c tiv i ty w h ich d ec ay s o u ts id e th e p a r t ic le , in te rm s of ra d iu s , R, the d iffu sion co effic ien t, 2> , and th e decay co n s tan t, X, of the d au g h te r .

F o r i l l u s t r a t i v e p u r p o s e s w e h a v e c o m p u te d th e y ie ld s f o r d a u g h te r s e p a r a t io n w ith p a r t i c l e s of r a d iu s R = 10-3 c m a s a fu n c tio n of h a l f - l i f e and d iffu s io n c o e ff ic ie n t of th e d a u g h te r . F o r th e c o m p u ta tio n s i t w as a s su m ed th a t th e c o n c e n tra tio n of p a re n t held by the p a r t i c le s re m a in e d c o n s ta n t an d th a t s u f f ic ie n tly r a p id flow c o n d itio n s a r e u s e d so th a t d a u g h te r d if fu s in g o u t o f th e p a r t i c l e s is im m e d ia te ly sw ep t aw ay . T h e r e s u l t s a r e p lo tte d in F ig . 14.

In sp ec tio n of th e fu n c tio n s p lo tted in F ig . 14 le a d s to a n u m b er of p r a c t ic a l co n c lu s io n s . F o r sm a ll p a r t ic le s in w hich d iffusion is re la tiv e ly rap id , fo r ex am p le , 2> = 10-5 c m 2 / s , i t is se e n th a t s e p a ra tio n of d a u g h te rs having h a l f - l iv e s of th e o r d e r of m il l is e c o n d s sh o u ld be p o s s ib le . H o w ev er, even if d iffu s io n is s low , f o r e x a m p le , 2 )= 1 0 -8 o r 1 0 ’ 9 c m 2 / s , a s i s f re q u e n tly o b s e rv e d w ith so m e io n ex c h an g e m a te r i a l s , a p p r e c ia b le s e p a r a t io n of d a u g h te rs h a v in g h a l f - l iv e s a s low a s a few se c o n d s ca n s t i l l be o b ta in e d .

A ty p ic a l r a p id e lu tio n e x p e r im e n t ta k e n f ro m e a r l i e r w o rk [ 14 ] i s show n in F ig . 15, w h e re th e s e p a ra tio n of 0 . 8 - s P b 201m f ro m i ts lo n g -liv e d p a re n t, Bi20"1 , i s i l lu s t r a te d . F o r th is s e p a ra tio n , the p a re n t w as a d so rb e d f ro m 0 .5 M H C l on u n ifo rm b e a d s of D ow ex - 1 a n io n e x c h a n g e r e s in (R = 3. 5 X 10-3 cm ). S in ce B i(III) is s tro n g ly a d s o rb e d by th e r e s in f ro m


Fig. 14.

Separation y ie ld as function of daughter h a lf - l ife and diffusion co effic ien t,® . (S pherical p a rtic le s , R = l ( f Sc m ).

Fig. 15

Rapid e lu tion of resin contain ing adsorbed Bi!07 . (F low -rate 17 c m /s ) .

th is m e d iu m , a h ig h e q u i l ib r iu m c o n c e n tra tio n of p a r e n t m a y b e r e ta in e d in a sha llow bed of r e s in by re c y c lin g . In F ig . 15A, th e d e c r e a s e of c o u n ting r a te of an e q u i l ib ra te d b ed on r a p id e lu tio n is show n. T h e d e c r e a s e of counting r a te , ap p ro x im a te ly 18%, is a s so c ia te d w ith the rem o v a l of P b 207m . On stopping th e flow the counting r a te rap id ly in c re a s e s to the o rig in a l counting r a te . If f r e s h e lu en t is u se d , r a th e r than re c y c le d so lu tion , a s ign ifican t f r a c t io n of th e p a r e n t d if fu s e s o u t d u r in g th e s e p a r a t io n a s i s i l l u s t r a t e d in F ig . 15B .

C o n v e rs e ly th e m e a s u re m e n t of the y ie ld of a p a re n t-d a u g h te r s e p a r a tio n ca n b e u se d to d e te r m in e th e d if fu s io n c o e ff ic ie n t of d a u g h te r s p e c ie s in th e ex ch an g e r p ro v id ed the p a r t ic le s iz e and the decay co n stan t a r e known.


T e c h n iq u e s of th is ty p e a r e s im p le an d r a p id an d sh o u ld f in d a n u m b e r of a p p l ic a t io n s in s tu d ie s in w h ich c h a n g e s in d if fu s io n r a t e s in p a r t i c u la te m a te r ia ls a r e of in te re s t a s a function of v a r ia b le s , such a s ex te rn a l so lven t com position , te m p e ra tu re o r co n tac t tim e .

T h e re la tio n s h ip betw een s e p a ra tio n y ie ld of s h o r t- l iv e d d a u g h te rs and d iffu s ion p ro v id e s a s e n s it iv e m eth o d fo r s tudy ing ag ing phenom ena in so lid o r g e l - l ik e m a te r i a l s [5] . A p a r e n t - d a u g h te r p a i r sh o u ld b e s e le c te d in w hich th e p a re n t is s tro n g ly a d s o rb e d by th e m a te r ia l w h ile th e d au g h te r is on ly w ea k ly h e ld . A f te r a d s o rp tio n of th e p a r e n t y ie ld m e a s u r e m e n ts can b e m a d e a s a fu n c tio n of tim e ; d u ra tio n of th e s tudy i s l im ite d on ly by th e h a l f - l i f e of th e p a r e n t . C h a n g es in th e d iffu s io n e n v iro n m e n t of th e s i te of th e p a r e n t a r e r e f le c te d by ch a n g e s in th e y ie ld .

A ty p ic a l ag in g s tu d y ta k e n f ro m an e a r l i e r p u b lic a tio n [5] i s show n in F ig . 16 w h ich sh o w s th e s e p a r a t io n of 2. 6 -m in B a l37m f ro m i t s p a r e n t , C s 137 , a d s o rb e d on a s m a l l co lu m n of z i rc o n iu m p h o sp h a te . T h e e lu tio n w as c a r r ie d out w ith 1 M H Cl s in c e C s is s tro n g ly a d s o rb e d f ro m th is m e d iu m w h ile B a i s w ea k ly a d s o rb e d , an d h e n c e m a y be r a p id ly re m o v e d by p u m p in g e lu e n t th ro u g h th e b ed .

4 Fig. 16137 137Separation of 2 .6-m in Ba from Cs . (Cs parent adsorbed on 1 m l 80-170 mesh zirconium phosphate).

T h e change in th e coun ting r a te of th e co lum n on e lu tio n w as m e a s u re d w ith a sodium iodide s c in tilla tio n co u n te r w hich view ed the sm a ll bed through a s l i t in a le ad sh ie ld . E s s e n tia l ly co m p le te s e p a ra tio n of B a 137mfro m C s i37

a d so rb e d on a bed of f re s h ly -p re c ip i ta te d z irc o n iu m phosphate w as ob ta ined on pum ping H C l th ro u g h th e bed a t a f lo w -ra te of 5 c m / s; ev en a f te r ag ing th e m a te r i a l f o r 640 h , o v e r 90% of th e d a u g h te r c a n b e s e p a r a te d . W ith o th e r s a m p le s ag e d a s lo n g a s fo u r y e a r s , a s m u c h a s 85% of th e B a i37i” m ay be rem o v e d , in d ic a tin g th a t th is m a te r ia l d id not change ra d ic a lly even a f te r a p ro lo n g ed ag ing p e r io d .


T h e s tu d y of ag in g by th e te c h n iq u e d e s c r ib e d a p p e a r s to be s u p e r io r to m ethods in w hich a d so rp tiv e p ro p e r t ie s a r e te s te d by s e p a ra te ad so rp tio n m e a s u re m e n ts c a r r ie d out o v e r a p e r io d of t im e . R egions in th e so lid w hich m ig h t h a v e b ec o m e in a c c e s s ib le d u r in g a g in g w ou ld n o t be a s r e a d i ly d e te c te d a s in m ilk in g m e th o d s .


W e a r e in d e b te d to M r s . D onna C . M ic h e lso n f o r v a lu a b le te c h n ic a l a s s i s t a n c e in p r e p a r in g th e L aF 3 and d e te r m in in g s o lu b i l i t i e s an d to M r . R . L . S h e rm a n f o r th e X - r a y a n a ly s e s .

R E F E R E N C E S

[1] KRAUS. K .A ., MICHELSON. D .C . and NELSON. F . , J. A m . C hem . Soc. 8 1 (1 9 5 9 ) 3204.[2] (a ) MOORE. G .E . and KRAUS, K. A . . J. A m . C hem . Soc. 74 (1952) 843.

(b) KRAUS, K .A . and MOORE, G .E . , J. Am. C hem . Soc. 7 5 (1 9 5 3 ) 1460.[3] KUSAKA, Y. and MEINKE, W. W .. "Rapid radiochem ical Séparations" (Rept NAS-NS No. 3104.Dec.1961)

Nat. Acad. S c ie n ., Nat. Res. Council, Off. Techn. Serv, Dept, of C om m ., Wash. D .C .[4] NELSON, F . , HOLLOWAY, J .H . , HAUSCHILD, J.A . and KRAUS. K .A .. to be published.[5] KRAUS, K. A ., PHILLIPS, H. O. and NELSON, F . , "Radioisotopes in the Physical Sciences and Industry"

(Sept, 1960) IU IAEA, Vienna (1932) 387-406.[6] KURY, I. W ., Univ. of C alit. Radiat. L ab .. Rept No. UCRL-2271 (1953).[.'] (a) KRAUS, K .A . and NELSON, F . , Proc. UN Int. C o n f., PUAE. 7 (1956) 113, 131;

(b) NELSON, F . , RUSH, R. M. and KRAUS, K .A . , J. Am. Chem .*Soc. 82(1960) 339:(c) KRAUS, K. A. and NELSON, F . , Amer. Soc. for Testing M aterials, Special Techn. Publ. No. 195(1958).

[8] KRAUS, K .A . and NELSON, F . , in: "The Structure of e lectro ly te Solutions", (W. J. H am er ed. ) , John W iley and Sons, N. Y. (1959) Ch. 23.

[9] HAHN, O. and MÚLLER. O. , Z . E lectrochem . 29 (1923) 189.[10] WAHL, A .Ç . , in : "Radioactivity applied to Chem istry", (A. C. Wahl and N. Bonner, Eds), John Wiley

and Sons, I n c . . N. Y. (1951) Ch. 9 . 284.[11] WANG, J. H . , in : "Radioactivity applied to C hem istry", (A .C . Wahl and N. Bonner, Eds), John Wiley

and Sons, I n c . , N. Y. (1951) Ch. 4 . 62.[12] Du DOMAINE, J . . SWAIN, R.L. and HOUGEN. O .A . , Ind. Eng. C hem . 35(1943) 546.[13] BOYD, G .E ., ADAMSON, A . W. and MYERS. L .S . . J. Am. C hem . Soc. 69(1947) 2836.[14] CAMPBELL, E .C . and NELSON, F . , J. Inorg. N uclear C hem . 3 (1 9 5 6 ) 233.[15] WALL, F . T . , GRIEGER, P .F . and CHILDERS, C . W ., J. A m . C hem . Soc. 7 4 (1952) 3562.[16] ANDERSON, J. and S ADDING TON, K. . J. C hem . Soc. S 3 8 1 (1949).[17] GRÛN, F. and BLATTER, C . , J. Am. C hem . Soc. 80 (1958) 3838.[18] NELSON. F . . J. Polym er S c i . . 40 137 (1959) 563.[19] PHILLIPS, H. O. and KRAUS, K. A. , unpublished results.

D I S C U S S I O N

W. PA U L: H ave you h ad any e x p e r ie n c e w ith th e e lu tio n of g a lliu m -6 8 f ro m g e rm a n iu m -6 8 ?


F . N ELSO N : W e h av e n o t s tu d ie d th is p a r t i c u la r n u c le a r s y s te m , a l though we have s e p a ra te d th e e le m e n ts f ro m each o th e r by ion exchange and o th e r te c h n iq u e s . T h e s e p a ra t io n of g a lliu m and g e rm a n iu m is not d ifficu lt b e c a u s e th e y b eh a v e so d if fe r e n t ly . F o r e x a m p le , g e rm a n iu m c a n e a s i ly be d is t i l le d f ro m c o n c e n tra te d H Cl so lu tio n s , and w e have u se d th is m ethod to s e p a ra te a 0. 5 - s g e rm a n iu m d a u g h te r f ro m an a r s e n ic p a re n t; the sam e te c h n iq u e sh o u ld be a p p lic a b le to g e rm a n iu m -g a l l iu m s e p a ra t io n s in c e the l a t t e r a l s o is no t v o la t i le . A s f o r a m ilk in g te c h n iq u e , in w h ich a g a lliu m d a u g h te r i s r e m o v e d f ro m a g e rm a n iu m p a r e n t , ion ex c h an g e w ou ld p r o b a b ly b e s u i ta b le b u t w e h a v e n o t in v e s t ig a te d o r t e s te d su c h a m e th o d .

P . STANG: R e fe r r in g to M r . P a u l ’s q u e s tio n c o n c e rn in g th e m ilk in g of Ga68 f ro m G e6 8 , I w ould s im p ly lik e to p o in t out th a t such w ork w as done a t B ro o k h av e n ab o u t tw o y e a r s ago an d i s r e f e r r e d to in th e s e c tio n of m y p a p e r ( th e s e p ro c e e d in g s ) d ev o ted to p a r e n t-d a u g h te r "m ilk in g " s y s te m s . T h is w o rk h a s a ls o b ee n p u b lish ed in one of th e jo u rn a ls and I cou ld supp ly th e r e f e r e n c e if r e q u ir e d .

PRODUCTION ET UTILISATION DES ISOTOPES SODIUM-24, POTASSIUM-42, CUIVRE-64

ET MOLYBDÈNE-99

R. LOOSDÉPARTEMENT DE PHYSIQUE, UNIVERSITÉ LOVANIUM,

CONGO (LÉOPOLDVILLE )


PRODUCTION AND USE OF THE ISOTOPES SQDIÜM-24,POTASSIUM-42,COPPER-64 AND MOLYBDENUM-9Ü The Lovanium University, Leopoldville, is working in close co-operation with the TRICO Centre, which operates a TRIGA reactor (General Atomics) with a m axim um power output of 50 kW and distributes isotopes to the University’s laboratories and other users. The elem ents are norm ally irradiated in the reactor’s rotary specimen rack under a flux of 3 x 1Û*1 n /cm * s, but in some special cases they are placed in the central thim ble where there are 2. 5 x Ю1г n /cm * s at the point of m axim um flux. As there are no fac ilities for the chem ical treatm ent of h igh ly-active substances the samples are irradiated in a suitable chem ica l foim ; gam m a spectrom etry (w ith a 400-channel analyser) is used to ensure that no unwanted isotopes are present.

Counting is usually done with single-channel analysers. In the case of Cu*4, a device embodying twin detectors in coincidence has been used to check certa in m easurem ents. The m ultichannel analyser is to be used for experim ents involving two radioactive tracers.

The following isotopes, in ter a l ia ,a re being uséd: (1) Na24, К42 and Cu64 in the Physiology Laboratory to obtain curves describing the circulation, distribution and distribution kinetics of the various isotopes;(2) K42 in the Pharmacology Laboratory, to determ ine the influence of various pharm aceutical products on ion movem ents and to study the fixation of Cub4 by the unstriped muscles and the e ffect which this isotope has on the action of drugs; (3) M o" in the Microbiology Laboratory óf the Faculty of Agronomy to study the physiological effects and the distribution of molybdenum in plants arid to develop m icrobiological methods of determ ining m olybdenum.

PRODUCTION ET UTILISATION DES ISOTOPES SbBlUM-24,POTASSIUM-42,CUIVRE-64ET MOLYBDÈNE-99. L’U niversité Lovanium de Léopoldville trava ille en é tro ite collaboration avec le Centre TRICO, qui dispose d ’un réacteur TRIGA (General Atomics) d ’une puissañbé m axim ale de 50 kW e t qui distribue des isotopes aux laboratoires de l'U niversité pu â d 'au tres utilisateurs éventuels. Les irradiations se font généralem ent dans la couronne ro ta tive (flux 3 . 1011 n /c m 2 s. ); dans des caá spèciaux le tube centra l est utilisé (2 ,5 * 1012 n /cm * s. au point de flux m axim um ). A cause de l ’absence de m oyens de m anipu lation chim ique de substances très actives on irradie les échantillons pous une forme cHiiriique appropriée; on vérifie l ’absence d ’isotopes gênants par spectrom étrie gam m a (analyseur â400 canaux).

Les comptages se font généralem ent au moyen d ’ânalyseurs â un canal. Dans le cas du cuivre-64certaines mesures ont é té contrôlées par un dispositif â deux détecteurs en coïncidence. Pour les expériences utilisant deux indicateurs l'em p lo i de l'analyseur m ulticanâüx a é té envisagé.

Parmi les utilisations, signalons: 1. au laboratoire de physiologie la déterm ination des courbes de passage circulatoire, distribution e t Cinétique de distribution de différents isotopes (sodium-2 4 ,potassium-4 2 ,cuivre-64);2. au laborato ire de pharm acologie, l 'é tu d e de r in ñ u e n c e de diverses conditions pharm acologiques sur les mouvements ioniques (potassium-42) ainsi que l ’étudè' de la fixation du cuivre-64 par les muscles lisses e t ses relations avec les actions pharm acologiques de ce ü é ta l ; 3. au laborato ire de m icrobiologie de la Faculté agronomique, l ’étude du rôle physiologique e t de la répartition du molybdène dans les plantes (m olybdène-99) ainsi que le contrôle de la m ise au point de méthodes m jcrobiologiques pour la déterm ination du molybdène.

ПРОИЗВОДСТВО И ПРИМЕНЕНИЕ ИЗОТОПОВ НАТРИЯ-24, КАЛИЯ-42, МЕДИ-64 И МОЛИБДЕНА-99. Леопольдвильский университет Лов&ниум работает в тесном сотрудничестве с центром Трико, который располагает реактором Трига (ДхеНёрал Атомикс) с максимальной мощностью в 50 квт и поставляет изотопы лабораториям университета или другим потребителям. Как правило, облучение производится в ро

215

216 R. LOOS

тационной короне (плотность потока 3,1011н/сек.сма); в специальных случаях используется центральный канал (2,5»1012н/сек.см2 при максимальной плотности потока). В связи с отсутствием средств химической обработки высоко активных веществ прибегает к облучению образцов в соответствующей химической форме; отсутствие изотопов с задерханным распадом проверяется с помощью гамма-спектрометрии (400-канальный анализатор).

Отсчеты производятся, как правило, с помощью одноканальных анализаторов. В случае с медью-64 некоторые измерения были проконтролированы с помощью прибора из двух счетчиков на совпадениях. В опытах с использованием двух индикаторов предусмотрено применение многоканального анализатора.

Необходимо отметить применение многоканального анализатора в следующих пунктах:1) в лаборатории физиологии: кривые кровообращения, распределение и кинетика распределения

различных изотопов (натрия-24, калия-42, меди-64);2) в лаборатории фармакологии: влияние различных фармакологических условий на двихение ионов

(калиЙ-42); фиксация меди-64 гладкой мускулатурой и связь с фармакологическим действием этого металла;

3) в лаборатории микробиологии агрономического факультета: исследование физиологической роли и распределения молибдена в растениях (молибдена-99); контроль за разработкой микробиологических методов определения молибдена.

PRODUCCIÓN Y EMPIÆODE LOS ISÓTOPOS SODIO-24, POTASIO-42, COBRE-64 Y MOLIBDENO-99. La Universidad Lovanium de Leopoldville trabaja en estrecha colaboración con e l centro TRICO, que dispone de un reactor TRIGA (General Atomics) de una potencia m áxim a de 50 kW y distribuye isótopos a los laboratorios de la Universidad y a otros usuarios eventuales. Las irradiaciones se efectúan generalm ente en la corona g i ratoria ( f lu jo 3 .10U n/cm ^s); en casos especiales, se u tiliza e l canal cen tra l (2 ,5 x 1012 n /cm 2s en e l punto de flujo m áxim o). Com o se carece de medios de m anipulación quím ica para las sustancias muy activas, se procede a irradiar m uestras consistentes en productos quím icos de forma adecuada ; la ausencia de isótopos no deseables se com prueba por espectrom etría gam m a (analizador de 400 canales).

Los recuentos se e fectúan generalm ente con analizadores de un solo cana l. En e l caso d e l cobre-64 ciertas m ediciones se han controlado con un dispositivo de dos detectores en coincidencia. Se ha previsto e l em pleo de l analizador m ulticana l para los experim entos en que intervengan dos indicadores.

El autor señala algunos de los fines para que se em plean los radioisótopos:1. En e l laboratorio de fisiología: curvas de flujo circulatorio , distribución y cinética de la distribución

de diversos isótopos (sodio-24,potasio-42, cobre-64).2. En e l laboratorio de farm acología: influencia de diversas condiciones farm acológicas sobre los des

plazam ientos de los iones (potasio-42); fijac ión de l cobre-64 por los músculos lisos y sus relaciones con la activ idad farm acológica de este m e ta l.

3. En el laboratorio de microbiología: estudio de l’a*función fisiológica y de la distribución delmolibdeno en las plantas (molibdeno-99); control del perfeccionamiento de métodos microbiológicos para la determinación del molibdeno.

1. INTRODU CTION

L o rs du co llo q u e s u r la r e c h e r c h e en p h y siq u e au m o y en de n e u tro n s é m is p a r le s p ile s , q u i a eu lie u à V ienne en 1960, G IL L O N [l] a d é jà d é c r i t , d ’une façon g é n é ra le , l ’équ ipem ent e t le s a c tiv i té s du 'C en tre TRICO de L éopo ldv ille .

L e r é a c te u r du C e n tre TR IC O e s t in s ta l lé à c o u r te d is ta n c e d e s la b o r a to i r e s d e s F a c u l té s d e s s c ie n c e s , de m é d ec in e e t d ’a g ro n o m ie de l ’U niv e r s i t é . C e c i re n d p o ss ib le une é t ro i te co lla b o ra tio n e n tre le s deux in s t i tu t io n s . L e s c h e rc h e u r s de l ’U n iv e rs ité son t a c tu e lle m e n t le s p rin c ip au x u t i l i s a te u r s du r é a c te u r e t d es iso to p e s p ro d u its .

2. É Q U IPEM EN T POUR LA PRODUCTION DE RADIOISOTOPES

Le C en tre TRICO d isp o se d ’un r é a c te u r k p isc in e du type TRIGA M ark 1, c o n s tru i t p a r G e n e ra l A to m ic s . L a cuve e s t m o n tée p ro v iso ire m e n t so u s le

PRODUCTION ET UTILISATION DES ISOTOPES 24Na, ^ K , MCu et "M o 217

n iveau du so l. P lu s ta r d le r é a c te u r s e r a t ra n s fo rm é en TRIGA M ark 2, avec la p isc in e m ontée a u -d e s su s du so l, ce qui p e rm e ttr a d ’ob ten ir des fa isceau x de n e u tro n s h o r iz o n ta u x e t t r è s in te n s e s p o u r d e s r e c h e r c h e s p lu s a p p r o fo n d ies en p h y siq u e n u c lé a ire e t en ra d io b io lo g ie , p a r ex e m p le , p o u r a n im au x . D ans son é ta t a c tu e l i l s e r t su r to u t cl la p ro d u c tio n de ra d io é lé m e n ts e t Ъ. l ’i r r a d ia t io n au m oyen de ra y o n s g am m a ou de n e u tro n s . L a p u is sa n c e m a x im a le du r é a c te u r e s t 50 kW.

P o u r la p ro d u c tio n de r a d io é lé m e n ts on d isp o s e de t r o i s p o s s ib i l i té s :a) L a couronne ro ta tiv e p la cé e dans le ré f le c te u r au g rap h ite en to u ran t

le noyau; e l le c o n tien t-40 tu b e s pouvant r e c e v o ir d es é c h a n tillo n s co n ten u s d a n s d e s tu b e s d e polyth tene. L e s é c h a n tillo n s so n t r e t i r é s au m o y en d ’un t r e u i l qui le s mfene dans un r é s e r v o i r en plom b, ce qui p e rm e t de le s t r a n s p o r te r s a n s e x p o s e r le p e rs o n n e l aux ra d ia t io n s . L e f lu x de n e u tro n s dans l a c o u ro n n e e s t de 3 • 1011 n /c m 2 • s k 50 kW .

b) L e tu b e p n eu m atiq u e qu i rhtene le s é c h a n tillo n s en un e n d ro it du r é a c te u r оЪ le flux e s t de 1012 n / c m 2- s à 50 kW, L ’éch an tillo n peu t ê t r e r e t i r é rap id e m e n t. L ’in s ta lla tio n ne p e rm e t cependant p as une ir ra d ia tio n d ép assan t5 à. 10 m in , à c a u se de ré c h a u ffe m e n t de la so u ffle r ie , de s o r te que, g é n é ra le m en t,o n ne peut p a s l ’u t i l i s e r p o u r la p roduction d ’a c tiv ité s é le v é e s .

c) L e tu b e c e n t r a l du<noyau p e r m e t la p ro d u c tio n d ’é c h a n t illo n s trfes a c tif s ; le flux m ax im u m y e s t de 2,5 • 10 12 n /c m 2, s . L ’em plo i de ce tube e s t p lu s d é l ic a t que p o u r la co u ro n n e . On d esce n d l ’é c h an tillo n dans le tube au m oyen d ’une f ic e lle qu i p o r te une p e t ite m a s s e de p lom b . L ’é c h an tillo n e s t f ix é s u r la f ic e lle à une te l le d is tan c e a u -d e s s u s du plom b,que lo rsq u e ce lu i- c i touche le fond de la c u v e ,l’éch an tillo n se tro u v e à l ’e n d ro it du flux m a x im u m du tu b e c e n t r a l . P u is q u e le to u t e s t im m e r g é d a n s l ’eau de la cuve, l ’é c h a n tillo n e t le p lo m b so n t s c e l l é s d an s d e s s a c s en m a t iè r e p la s t iq u e .

3. D ISTRIBU TIO N DU F L U X DE NEUTRONS DANS L E T U B E C E N T R A L

P o u r u t i l i s e r le tu b e c e n tr a l av ec un re n d e m e n t m a x im u m la p o s it io n du po in t de flux m a x im u m d o it ê t r e connue av ec su ffisa m m e n t de p ré c is io n . O n p o u r r a i t m e s u r e r l ’a c t iv i té de f e u i l le s d ’o r d e s c e n d u e s à d e s n iv e au x d i f f é r e n ts d a n s l e tu b e c e n t r a l e t i r r a d i é e s à l a m ê m e p u is s a n c e p e n d a n t le m ê m e te m p s e t d é te r m in e r a in s i la p o s itio n du m ax im um ; c e c i n é c e s s ite d e s o p é r a t io n s m u l t ip le s . P o u r é v i te r c e t en n u i n o u s a v o n s s u g g é ré un e m éth o d e con tinue au m oyen d ’un f i l m é ta lliq u e ( te l que du c u iv re ) d escen d u v e r t i c a le m e n t d a n s le tu b e c e n t r a l . A p rè s i r r a d ia t io n , on p eu t m e s u r e r l ’a c t iv i té le lo n g du f i l en le f a is a n t p a s s e r so u s un c o m p te u r . L e s e x p é r ie n c e s ont é té f a i te s p a r RO ELS 12], du C e n tre TRICO ; il tro u v e une c o u rb e de d is t r ib u t io n lé g è re m e n t a s y m é tr iq u e ay an t un m a x im u m c o r r e s pondant au niveau de 32 cm sous le n iveau su p é r ie u r du noyau. P o u r m o n tre r l ’im p o r ta n c e d es v a r ia tio n s ,d o n n o n s q u e lq u es c h if f re s com m e e x e m p le : au n iveau de 6 cm l ’a c tiv ité ob tenue n ’e s t que 36,8% de l ’a c tiv ité m ax im um obtenue à 32 cm ; on a 79% à 22 cm , 92% à 26 cm , 96% à 28 cm , 98, 6% U 30 cm ; e n s u ite on a 99, 3% b. 34 cm , 98% à 36 cm , e tc . L a c o u rb e e s t b ie n r e p r o d u c tib le . A u s s i à d e s p u is s a n c e s d if fé re n te s on re tro u v e la m ê m e fo rm e de d is tr ib u t io n avec un m ax im u m à 32 cm .

218 R. LOOS

A in s i on co n n a ît le po in t du tube c e n tr a l оЪ l ’on do it a m e n e r le s éc h an t i l lo n s p o u r o b te n ir une a c tiv ité m ax im um e t pou r pouvoir c a lc u le r l ’ac tiv ité avec le m ax im um de p ré c is io n .

4 . TRA ITEM EN T DES ÉCHANTILLONS IRRADIÉS

L e tr a i te m e n t ch im iq u e d e s p ro d u its i r r a d ié s ne peu t p as d é p a s s e r une c e r t a in e d u ré e s ’i l s ’a g i t d ’is o to p e s d e c o u r te p é r io d e . I l d o it a u s s i ê t r e f a i t d an s d e s c o n d itio n s qu i g a r a n t is s e n t la p ro te c tio n du p e rs o n n e l c o n tre l e s ra d ia tic in s . L e C e n tr e T R IC O n e d is p o s e p a s e n c o r e de l ’é q u ip e m e n t n é c e s s a i r e aux m an ip u la tio n s ch im iq u es p a r fo is com pliquées d ’éch an tillo n s t r è s a c t i f s . A in s i on a dû se l im i te r à la p ro d u c tio n d ’é c h a n tillo n s pouvant ê t r e l iv r é s aux u t i l i s a te u r s s a n s tra i te m e n t ch im ique p ré a la b le . C es éch an t i l lo n s ne peuven t donc p a s c o n te n ir des ra d io é lé m e n ts in d é s ira b le s e t le u r c o n s titu tio n ch im iq u e ne peu t p a s ê t r e m o d ifiée p a r l ’i r ra d ia t io n .

D an s le c a s du so d iu m , du p o ta s s iu m e t du c u iv re , une p u r e té r a d io - ch im iq u e su f f is a n te a é té o b ten u e p a r l ’em p lo i de p ro d u its p o u r l ’a n a ly s e . On a a ttendu su ffisam m en t lon g tem p s pou r p e rm e ttr e la d é s in té g ra tio n co m p lè te d es iso to p e s =l p lu s c o u r te d u ré e de v ie que l ’iso to p e voulu . Le sp e c tre d e s ra y o n s g am m a a é té v é r if ié au m oyen d ’un a n a ly se u r m onocanal, e t d e p u is le m o is de m a i a u s s i au m oyen d ’un a n a ly se u r à 400 canaux RIDL. P our d im in u e r e n c o re l e s r i s q u e s d ’e r r e u r on a f a i t une p a r t i e d e s c o m p ta g e s au m o y e n d ’u n a n a ly s e u r m o n o c a n a l. D an s l e c a s du c u iv re -6 4 c e r t a in e s m e s u re s ont é té c o n trô lé e s p a r la m e s u re d es co ïn c id en ces d es deux ray o n s g am m a p ro v en an t de l ’an n ih ila tio n des p a i re s p o s it ro n s -é le c tro n s .

D ans le c a s du m o ly b d è n e le s p ro d u its e m p lo y é s n ’o n t p a s donné d e s é c h a n tillo n s i r r a d ié s su ffisa m m e n t p u r s . D es e s s a is de s é p a ra tio n son t en c o u r s (v o ir VAN P E E [3]). L e m olybdène é ta it i r r a d ié pendant deux h e u re s so u s fo rm e de m olybdénate de sodium ou d ’am m onium , pu is m is en solution e t p a s s é s u r une co lo n n e d ’é c h a n g e u r d ’io n s ( a m b e r l i te 400R) d a n s le but d ’a b s o rb e r le s im p u r e té s e t de l a i s s e r p a s s e r le m o ly b d èn e . A fin de c o n t r ô l e r la p u re té ra d io c h im iq u e d es f ra c tio n s é luées , on m e s u re le u r p é rio d e e t le p o uvo ir de p é n é tra tio n d es ray o n s b ê ta (avec d es a b s o rb e u rs en a lu m in ium ).

D ans c e r ta in s c a s il y a u ra i t avan tage à p u r if ie r le s éc h an tillo n s avant l ’i r ra d ia t io n ou k e m p lo y e r d e s p ro d u its sé le c tio n n é s .

Un a u tre r is q u e e s t la m o d ific a tio n de la co m p o sitio n ch im ique , ce qui peu t n é c e s s i te r d e s m a n ip u la tio n s ch im iq u e s a p r è s ir ra d ia t io n . Au C e n tre TR IC O on a c h o is i d e s fo rm e s ch im iq u e s so it d ire c te m e n t u ti l is a b le s , so it t r a n s f o r m a b le s av ec un m in im u m de m a n ip u la tio n s . A in s i le sod ium e t le p o ta s s iu m ont é té i r r a d i é s so u s fo rm e de c a rb o n a te ; c e lu i - c i e s t e n s u ite d is s o u s dans l ’eau et la so lu tio n e s t n e u tra lis é e avec l ’ac id e voülu (HCl p a r e x e m p le ) . P o u r l e s e x p é r ie n c e s av e c le cu iv re -6 4 ,o n a i r r a d i é le su lfa te ou le c h lo ru re p o u r m e ttr e c e s s e ls en so lu tion sa n s a u tre tra ite m e n t, a p rè s a v o ir a ttendu la fin de la d é s in té g ra tio n des iso to p es de t r è s co u r te p ério d e . I l a é té a d m is que , s i l ’i r r a d ia t io n p ro d u it p a r exem ple un c e r ta in n o m b re d ’io n s m o n o v a len ts , i l s ’é ta b l i ra un é q u ilib re dans la so lu tion , de s o r te que f in a le m e n t la c o n c e n tra tio n en io n s m o n o v a le n ts de 64Cu s e r a m in im e .

S i l ’é lé m e n t c o n s id é r é e s t in c o rp o r é d a n s un ion c o m p o sé , i l y a u r a fo rm a tio n d ’a u t r e s ty p e s d ’io n s e t i l ne s ’é t a b l i r a p a s n é c e s s a i r e m e n t un

PRODUCTION ET UTILISATION DES ISOTOPES MNa, ^ K , MCu et "M o 219

é q u ilib re . D ans ce ca s un tra i te m e n t ch im ique doit t r a n s fo rm e r tou t l ’échant il lo n i r r a d ié dans le co m p o sé voulu ou é l im in e r le s co m p o sés in d é s ira b le s . L ’e m p lo i d ’un é c h a n g e u r d ’io n s , co m m e d an s le c a s du m o ly b d é n a te , peu t r é a l i s e r c e t te o p é ra tio n en m ê m e te m p s qu e l ’é l im in a tio n d e s im p u r e té s r a d io a c t iv e s .

5. PROGRAM M ES DE REC H ER CH ES TER M IN EES OU DE REC HER CH ES EN COURS

L a l im i ta t io n p r e s q u e e x c lu s iv e Ъ. d e s f o r m e s c h im iq u e s u t i l i s a b le s d i r e c te m e n t a p e r m is au C e n tr e TRICO, d a n s so n é ta t a c tu e l ,d e p r o d u ire un g ra n d n o m b re d ’éc h a n tillo n s p o u r s a t is f a i r e aux b e so in s d e s c h e rc h e u rs d a n s l e s d if fé r e n ts la b o r a to i r e s de l ’U n iv e r s i té . N ous ne c i te r o n s ic i que l e s p ro g ra m m e s oti l e s iso to p e s de c o u r te p é r io d e ont é té u t i l i s é s co m m e é lé m e n ts m a rq u é s .

D an s l e s a p p l ic a tio n s b io lo g iq u e s d é c r i te s , la d u r é e d e s e x p é r ie n c e s ne d é p a s s a i t p a s q u e lq u e s h e u r e s , so it m o in s que la p é r io d e d e s is o to p e s u t i l i s é s . A u tan t qu e p o s s ib le l e s m e s u r e s d e l a r a d io a c t iv i té d e s é c h a n t i l lo n s d ’u n e m ê m e e x p é r ie n c e é ta ie n t g ro u p é e s a f in de d im in u e r l a c o r r e c t io n de d é s in té g ra t io n .

Au D é p a rte m e n t de p hysio log ie , BORGHGRAEF, LONI et HAUMONT [4] ont u t i l is é le sodium -24 e t le p o ta ssiu m -4 2 dans l ’étude d ’éch an g es sod ium - p o ta ss iu m et dans l ’an a ly se de co u rb e s de p a s sa g e c irc u la to ire de d iffé ren ts r a d io é lé m e n ts . Une p a r t i e im p o r ta n te d e s r e c h e r c h e s a é té c o n s a c ré e au m é ta b o lis m e de c e r ta in s m é tau x , n o ta m m e n t le c u iv re (64Cu) m a is su r to u t l e z in c . C e d e r n ie r t r a v a i l a é té r é a l i s é au m o y e n de l ’is o to p e à lo n g u e p é rio d e , 65z n , e t ne s e r a donc p a s d is c u té ic i . L e but de c e s r e c h e r c h e s e s t d ’é tu d ie r l a d is t r ib u t io n d e s m é ta u x d a n s to u s l e s o r g a n e s à d e s te m p s s ’échelonnan t e n tre 1 à 4 h a p r è s une in jec tio n in tra v e in e u se . On fa it v a r ie r l a d o se in je c té e e t on é tu d ie a u s s i l ’in f lu e n c e de d if fé r e n ts c o m p é ti te u r s , in h ib ite u rs et c h é la te u r s . D ans la su ite du t r a v a i l on é tu d ie ra a u s s i la c in é tiq u e de la d is t r ib u t io n apr%s d es te m p s e n c o re p lu s c o u r ts , p a r e x e m p le de 15 en 15 m in .

Au D é p a rte m e n t de p h a rm a c o d y n a m ie , GODPRAIND e t G O D FR A IN D - DE B EC K ER [5] ont u t i l i s é le cu iv re -6 4 p o u r l ’a n a ly se du m ode de l ia is o n du c u iv re dans un m u sc le . Le cu iv re p o ssèd e à la fo is la p ro p r ié té d ’e x c ite r le m u sc le l i s s e de l ’iléo n de cobaye e t c e lle d ’in h ib e r de faço n co m p é titiv e l ’a c tio n de l ’h is ta m in e e t de l ’a c é ty lc h o l in e s u r le m ê m e m u s c le . I ié tu d e a m o n tré q u ’une p a r t ie du c u iv re e s t l ié e de façon la b ile e t e s t r e s p o n sa b le d e l ’e x c ita t io n du m u s c le ; u n e a u t r e p a r t i e e s t l ié e de fa ç o n s ta b le e t e s t re sp o n sa b le de l ’an tag o n ism e . C ec i co n firm e la th é o rie de P aton qui a t tr ib u e a u x a g o n is te s une c o n s ta n te de d is s o c ia t io n é le v é e , au x a n ta g o n is te s une c o n s ta n te de d is s o c ia t io n f a ib le .

I l a é té m o n tré ég a le m e n t que l ’on peu t d is t in g u e r deux p h a s e s p o u r la v i te s s e re la tiv e de cap ta tion du64Qu p a r le m u sc le l is s e . La p re m iè re phase a une g ra n d e v i te s s e q u i ne dépend p a s de la c o n c e n tra tio n du m é ta l; d an s la seconde p h ase , la v i te s s e r e la t iv e e s t fonction de c e tte c o n c e n tra tio n [5].

Au m êm e d ép a rtem e n t, on a étud ié l ’ac tion de la d ig itox ine s u r le s m ouv em en ts du p o ta ss iu m -4 2 au n iveau de l ’iléon iso lé de cobaye [6]. Le m u sc le

220 R. LOOS

é ta i t p la c é d a n s un e so lu tio n de T y ro d e c o n te n a n t du 42KC1, a v e c ou s a n s ad d itio n de d ig itox ine ; la ra d io a c tiv ité du m u sc le é ta i t m e s u ré e à la s o r t ie du bain . La s o r t ie du KC1 a été m e su ré e égalem ent p a r la m éthode de Hurwitz. L e s e x p é r ie n c e s m o n tre n t q u 'i l e x is te un p a r a l lé l i s m e e n t re l ’a c tio n de la d ig ito x in e s u r le s éch an g es de p o ta ss iu m e t c e r ta in s f a c te u rs dont e s t fo n ctio n son a n ta g o n is m e v i s - à - v i s de l ’a c tio n d e s m é d ia te u r s c h im iq u e s s u r l ’i lé o n is o lé de c o b a y e .

Au D ép a rtem en t de m ic ro b io lo g ie de la F acu lté agronomique/VAN PEE[3] a fa it le s e s s a is p r é l im in a i r e s c i té s p lu s hau t en vue de p ro d u ire du m o lyb - dèn e -9 9 pou r le s r e c h e r c h e s su iv a n te s :

• a) Le co n trô le d ’une m éthode m ic rob io log ique pour d é te rm in e r la quan t i t é de m o ly b d è n e . L e m il ie u de c u l tu r e d o it ê t r e c o m p lè te m e n t l ib é r é de m o ly b d è n e . L e " M o p eu t ê t r e em p lo y é p o u r c o n t r ô le r la p u r if ic a tio n .

b) L ’é tude de la r é p a r t i t io n du m olybdène dans le s p lan tes e t le s nodules e t son in fluence s u r la f ixa tion de l ’azo te m o lé c u la ire .


[1] GILLON, L. P . , « U tilisa tio n du réacteur nucléaire de L éo p o ld v ille» , Pile Neutron Research in Physics, AIEA, Vienne (1962) 19.

[2] ROELS, J. F . , « D is trib u tio n du flux de neutrons dans l'ouverture cen tra le du réacteu r TRIGA Mark I à L é o p o ld v ille» , Rapport du C en tre TRICO 6 2 /02 , Léopoldville (1962) 1-12.

[3] VAN PEE, W ., C om m unication personnelle.[4] BORGHGRAEF, R. , LEONI, M .e t HAUMONT, A. , â paraître .[5] GODFRAIND, T. e t GODFRAIND-DE BECKER, A . , «A nalyse de Taction du cuivre, agoniste partiel pour

l 'iléo n de c o b a y e » , A rch .in t. de pharm acodyn., (sous presse).[6] GODFRAIND, T .e t GODFRAIND-DE BECKER, A. , « A c tio n de la digitoxine sur les mouvements du 42 к

au niveau de l'iléon isolé de c o b ay e » . Rapport annuel re la tif aux activités du Centre TRICO,TRICO 62/03(1962) 25-29.

SHORT-LIVED RADIOISOTOPE PRODUCTION, PROCESSING, DISTRIBUTION AND APPLICATIONS

IN KOREA

CHONG KUK KIMDEPARTMENT OF CHEMISTRY, ATOMIC ENERGY RESEARCH INSTITUTE,

SEOUL, KOREA


SHORT-LIVED RADIOISOTOPE PRODUCTION, PROCESSING, DISTRIBUTION AND APPLICATIONS IN KOREA. The production, processing and distribution of short-lived radioisotopes by the Atomic Energy Research Institute of Korea are discussed. The radioisotopes concerned are Na24, Cue4, K42, Md99, W187, colloidal Au® B i^m and I I » .

The paper also deals with applications of these isotopes in various fields in Korea. The m ost im portant application is the use of Na24 for the detection of leaks in irrigation w ater storage containers. Since there a ie nearly 1500 such containers in South Korea, the de tection o f leaks is a nation-w ide problem . Na24 is also applied to m etabolic studies in hypertension and to the study of the mixing mechanism in m iscible liquid-liquid phase systems.

PRODUCTION, TRAITEMENT, DISTRIBUTION ET APPLICATIONS DES RADIOISOTOPES A COURTE PÉRIODE EN COREE. L 'auteur décrit com m ent l'Institu t coréen de recherches sur l 'énerg ie atom ique produit, tra ite e t distribue des radioisotopes à courte période, notam m ent, 24Na, MCu, 42 K ,” M o,;187W, e iÀu colloïdal, к т в г e t i28I.

I l donne égalem ent un aperçu de l'em p lo i de ces radioisotopes dans différents dom aines en C orée. Le plus im portant consiste â u tilise r le sodium -24 pour d é te c te r les fuites des réservoirs d 'e a u d 'irrig a tio n . La C orée du Sud possède près de 1500 réservoirs de ce genre e t c 'e s t pourquoi le problèm e de la d é tec tio n deà fuites se pose â l'éche lon national. Le sodium -24 est égalem ent u tilisé pour des études métaboliques l 'h y p ertension e t pour des recherches sur le m écan ism e de m élange dans les systèmes m iscibles en phase liqu ide- liquide. Toutes ces études, faites â peu de frais, ont é té couronnées de succès.

ПРОИЗВОДСТВО КОРОТКОЖИВУЩХ ИЗОТОПОВ В КОРЕЕ, ИХ ОБРАБОТКА, РАССЫЛКА И ПРИМЕНЕНИЕ. Описывается производство, обработка и рассылка короткоживущих изотопов Исследовательским институтом по атомной энергии Кореи. Рассматриваются изотопы Na24, Cue4t К42, M o", W107, коллоидное золото Au 1аа, Вт eam Jl2a.

В докладе рассматривается также вопрос о применении этих изотопов в различных отраслях в Корее. Наиболее важным является применение Na24 для обнаружения утечки из ирригационных водохранилищ. Так как в Южной Корее имеется приблизительно 1500 таких водохранилищ, обнаружение утечки представляет собой общегосударственную проблему. Na24 применяется также для метаболических исследований при гипертонии и для изучения механизма смешения вэаимосмеоивагаихся систем жидкости жидкость.

PRODUCCIÓN, ELABORACION, DISTRIBUCIÓN Y APLICACIÓN DE RADIOISÓTOPOS DE PERÍODO CORTO EN COREA. La m em oria discute la producción, elaboración y distribución de radioisótopos de período corto en e l A tom ic Energy Research Institu te de C orea. Los radioisótopos en cuestión son e l 24Na, ^ u , 42K, **Mo, l « w t tóeAu co lo idal, 62mBr y iMl.

La m em oria tra ta tam bién de las aplicaciones de estos isótopos en diversas esferas. La más im portante es e l em pleo de í4Na para de tecta r fugas en depósitos de a lm acenam iento de aguas destinadas a l riego. Como en Corea de l Sur existen casi 1500 depósitos de esta clase, la de tecc ión de las fugas constituye un problem a de gran im portancia económ ica . El m ism o isótopo se ap lica tam b ién en estudios m etabó licos e n casos d e hipertensión y para investigar e l mecanismo de m ezcla en sistemas en fase líquido-líquido. Todos estos estudios se realizan con éxito y resultan poco onerosos.

221

222 CHONG KUK KIM

1. INTRODUCTION

In K o re a th e re is only one r e a c to r , a TRIGA M II, sw im m ing-poo l type w h ich h a s b een in o p e ra tio n a t i t s fu ll pow er of 100 kW s in c e 30 M arch ,1962 [1 ]. T he a v e ra g e flux in the c o re is about 1 .6 X 1012ncm *2 s ’1. T he fa c il i t ie s f o r ra d io iso to p e p ro d u c tio n c o m p ris e a r o ta ry sp e c im en ra c k w ith 40 ho les , know n a s L azy S usan , a c e n tr a l th im b le w h ere th e m ax im um n e u tro n flux is o b ta in ab le , (4 X 10ii: n c m 'z s ' 1) and a pn eu m atic s a m p le - tr a n s fe r r in g sy s te m (abou t 1 .3 X 10i2 n c m '2 s"1).

Of th e s e f a c i l i t i e s L a z y S u san h a s b e e n th e m o s t f re q u e n tly u se d f o r s h o r t - a n d lo n g -liv e d rad io iso to p e p ro d u c tio n . T he s h o r t- liv e d rad io iso to p es w h ich w e re in p ro d u c tio n up to th e end of A u g u s t,1962, ,a r e N a24, Cu64, K42, M oM, Wiij/, c o llo id a l Aui98, B r 82 and 1128. T h e s e iso to p e s a r e d is tr ib u te d to s e v e ra l m e d ica l c l in ic s in u n iv e rs i ty h o sp ita ls , a g r ic u ltu ra l co lleg es, .various in s t i tu te s an d to th e b io lo g y an d c h e m ic a l e n g in e e r in g d e p a r tm e n ts in th e A tom ic E n e rg y R e se a rc h In s titu te (AERI). D em ands fo r the sh o r t- liv e d rad io iso to p e s a r e in c re a s in g q u ite rap id ly , so th a t i t h as been n e c e s s a ry to o p e r a te th e r e a c to r a t fu ll pow er fo r 8 h a day s in c e 15 June , 1962.

No u se w as m ad e of s h o r t- l iv e d ra d io iso to p e s u n til th e r e a c to r b ecam e a v a ila b le in K o re a w ith the excep tion of 100 m e of co llo id a l Au198, w hich w as im p o r te d f ro m E n g land in e a r ly 1962. Iso to p e s w hich w e re u se d b e fo re th a t t im e w e re a l l lo n g - liv e d .

S in ce s h o r t - l iv e d n u c l id e s a r e p ro d u c e d m a in ly by th e (n, y) r e a c t io n w ith l i t t l e p r o c e s s in g an d a r e o b ta in a b le f r e e of c h a rg e a t an y t im e w hen th e y a r e n e e d e d fo r an e x p e r im e n t , s h o r t - l iv e d r a d io is o to p e s now h o ld a f a v o u ra b le p o s it io n in v a r io u s la b o r a to r ie s in K o re a , a lth o u g h th e r e a c to r h a s b e e n in o p e ra t io n f o r on ly 5 m o n th s . M o re o v e r , th e f a c ts th a t s h o r t - liv e d ra d io iso to p e s a r e f r e e of c h a rg e and th a t the w a s te -d is p o s a l p ro b le m s a r e m in im iz e d , m a k e th e s e is o to p e s w e ll s u ite d f o r K o re a n la b o r a to r i e s , in s t i tu te s and u n iv e rs i t ie s w hich su ffe r f ro m a g re a t la ck of r e s e a r c h funds.; T h e r a d io is o to p e s p ro d u ce d in K o re a have b een a p p lied fo r th e d e te c tio n of le a k s in i r r i g a t io n r e s e r v o i r s , th e m e a s u r e m e n t of tu r b u le n t d if fu s io n in liq u id s , th e s tu d y of th e c a th o d ic s tr ip p in g e ffec t, t r a c e im p u r ity d e te r m in a tio n of K o re an G inseng , m e tab o lic s tu d ie s in h y p e r te n s io n and tu m o u r d ia g n o s is . T h e re is no doubt th a t s h o r t- l iv e d ra d io iso to p e s w ill beco m e f a r m o r e f a m i l ia r to K o re a n s c ie n t i s t s , and w ill be ap p lied w idely in th e v e ry n e a r fu tu re , in th e p la c e of lo n g - liv e d n u c l id e s .

2 . PR O DU C TIO N AND PROCESSING O F SH O R T -L IV E D RADIOISOTOPES

P ro d u c tio n h a s b ee n c o n c e n tra te d on f iv e n u c lid e s [2]; th e s e a r e N a 24, K42, M o " , W-*-81 and c o llo id a l Au198.

Сий4, B r 82 and I 128 h av e b ee n p ro d u c e d l e s s f re q u e n tly .T h e t a r g e t m a te r i a l s u s e d f o r th e p ro d u c tio n w e re : N aC l an d N a 2C 0 3

f o r N a24, KC1 and K2C 0 3 f o r K42, ( N H ^ M o0 4 f o r Moaa,H 2W 0 4. H 20 fo r W187, c o l lo id a l go ld (USP) f o r A u ^ , c o p p e r m e ta l and C u (N 0 3) 2 f o r Cu64, CHgBr a n d С2 Н5 ВГ f o r B r 82, and C2H5I an d CH 3I f o r P 28.

T he h ig h e s t sp e c if ic a c tiv ity is no t a im ed a t s in c e long ir ra d ia t io n tim e w ould b e r e q u ir e d . T h e t a r g e t is w eighed an d s e a le d in a p o ly e th y le n e v ia l

SHORT-LIVED RADIOISOTOPE PRODUCTION, ETC. IN KOREA 223

o r tu b e and th en put in a s c re w -c a p p e d t r a n s p a r e n t p o ly e th y le n e c o n ta in e r . It i s th en le f t in the L azy S usan fo r th e p re -c a lc u la te d i r ra d ia t io n t im e . T he s a m p le i s r a i s e d a t th e end of th e i r r a d ia t io n by r e m o te c o n tro l , sh ie ld e d in a 2-in le a d c o n ta in e r and t r a n s f e r r e d to a ho t la b o ra to ry f o r p r o c e s s in g .

C h e m ic a l p ro c e s s in g is done a s fo llow s : N aC l, Си(Ж>з)2 and (N H ^ M 0O4

a r e d is s o lv e d in a know n am o u n t of d is t i l le d w a te r an d N a2C 0 3 in a know n vo lum e of s to ic h io m e tr ic a l c o n c en tra tio n of h y d ro c h lo r ic a c id . C o p p e r m e ta l i s d is s o lv e d in c o n c e n tra te d H C l an d th e pH a d ju s te d ; H2W 0 4.H 20 i s d i s s o lv e d in w ea k KOH so lu tio n ; an d B r ^ an d I128 a r e e x t r a c te d w ith 5 m l of l/lOOO M p o ta ss iu m iod ide c a r r i e r and 0.01 M NaHSÛ3 [3 ] .T h e c h e m ic a lly - t r e a te d s a m p le s a r e th e n t r a n s f e r r e d to c le a n g la s s v ia ls by p ip e ttin g , p u t in le a d c o n ta in e rs and sh ip p ed .

3. D ISTRIBU TIO N

S in ce th e r a d io is o to p e s a r e supplied- f r e e of c h a r g e th e m a jo r i ty o f K o re a n la b o r a to r i e s , in s t i tu te s an d u n iv e r s i t ie s a r e m a k in g u s e of th e m . T h e re q u e s t sh e e ts a r e su b m itte d to the A ER I w h e re they a r e c r it ic a H y r e v ie w e d , p a r t i c u l a r l y w ith r e g a r d to th e a m o u n t r e q u e s te d , th e p ro p o s e d dp.te of d e l iv e ry and w h e re th e is o to p e s a r e to be u s e d . T h e A E R I s u r v e y s th e f a c i l i t i e s a v a ila b le to ea ch u s e r , d is c u s s e s th e p u rp o se of th e p ro p o se d e x p e r im e n ts and d e c id e s if th e u s e r h as enough e x p e r ie n c e to enab le h im to h a n d le s h o r t - l iv e d r a d io i s o to p e s . A s a r e s u l t o f th e s u r v e y p r i o r i t y f o r d is tr ib u tio n is given and p roduction of th e req u e s ted rad io iso to p es is s ta r te d . T he u s e r s a r r a n g e th e ir own tra n sp o r ta tio n .

4. APPLICATIONS

4.1 T he m e a su re m e n t of tu rb u le n t d iffusion in liq u id s, u sing Na24

T h e lo n g itu d in a l tu rb u le n t d iffu s io n in w a te r th ro u g h a v e r t i c a l co lum n i s o b s e rv e d by in je c t in g Na24 a t th e to p of th e c o lu m n an d m e a s u r in g th e r a d io a c t iv i ty a t v a r io u s p o s i t io n s a lo n g th e co lu m n a s a fu n c tio n of t im e .

A s m a l l am o u n t of tu rb u le n c e i s p ro d u c e d by p u ls a tio n of th e w a te r a t th e bo ttom of the co lum n. T he tu rb u le n ce is g re a tly in c re a se d , and i ts m agn itu d e c o n tro l le d , by in te r f e r in g w ith th e w a te r flow by m e a n s of a s e r i e s of b a l ls a r r a n g e d along th e le n g th of th e co lu m n . T h e e x p e r im e n ta l v a r ia b le s a r e th e p u ls e a m p litu d e , p u ls e f re q u e n c y , b a l l s iz e an d d is ta n c e b e tw e e n s u c c e s s iv e b a l ls .

T he e x p e r im e n ta l r e s u l t s a g ré e w e ll w ith th e th e o ry w hich w as d e r iv e d f r o m th e lo n g itu d in a l d iffu s io n eq u a tio n and th e r e s u l t s a r e to b e u se d f o r th e a n a ly s i s of th e tu rb u le n c e a ro u n d th e s p h e re by p u ls a tio n .

4.2 D e te c tio n of th e le a k in K ihung ir r ig a t io n r e s e r v o i r , K yungki Do, Seoul,u s in g N a24 a s t r a c e r

T en to 15 m e of Na2\ in the fo rm of sod ium ch lo rid e , w as u se d a s t r a c e r a t one tim e . A geo lo g ica l study in d ica ted th a t the le ak in le t w as lo ca ted about 80 m f ro m th e p o in t w h e re th e dam m e e ts a m oun ta in n e a r to th e sh o re lin e .

224 CHONG KUK KIM

A fte r d ro p p in g one s a m p le p e r day a t 5-m in te r v a ls , a c tiv ity m e a su re m e n ts w e r e m a d e e v e ry 2 h u s in g a g a m m a w e ll- ty p e s c in t i l la t io n c o u n te r . A s a r e s u l t o f th e e x p e r im e n t th e le a k in le t w a s in f a c t lo c a te d only 52 m f ro m th e p o in t w h e re th e d am m e e ts th e m o u n ta in .

4.3 N eu tro n a c tiv a tio n a n a ly s is of vanadium , m anganese , coba lt and copper in ro o ts of G inseng p la n ts o c c u rr in g in d if fe re n t p a r ts of K o rea

By u s in g th e rm a l n eu tro n a c tiv a tio n a n a ly s is , about 0.02 ppm vanadium , 200 ppm m a n g a n e se , 0 .06 ppm c o b a lt an d 9 .4 -ppm c o p p e r h av e b een found in K um san G in sen g . T h e abundance of th e se t r a c e m e ta ls in G in sen g v a r ie d a c c o rd in g to the p a r t of th e co u n try in w hich th e p lan t w as grow ing . T he d e te rm in a tio n s w e re m ade by m ean s of gam m a sp e c tro m e try , u s in g 3 .7 -m inV 52, 2 .56 -h Mn56, 1 0 .5 -m in Co60mand 5 .1 -m in C u66.

4.4 C athodic s tr ip p in g effec t fo r se p a ra tin g m olybdate fro m tungsta te

T h e se p a ra tio n of m o lybda te f ro m a m ix tu re of m o lybdate and tu n g sta te by m e rc u ry ca thod ic s tr ip p in g is u n d e r in v e s tig a tio n . T he 24-h nuclide W187 and 6 7 rh M o " have b een u se d ia s t r a c e r s in th e study .

4.5i B io ch e m ica l and m e d ic a l a p p lica tio n s of Na24 and K42

R e s e a rc h is being u n d e r ta k e n in a n u m b e r of u n iv e rs i t ie s and h o sp ita ls on exchangeab le sodium and p o ta ss iu m in the liv ing body, the uptake of sodium and p o ta ss iu m in c a n c e ro u s t is s u e s , tu m o u r d ia g n o sis and m etab o lic s tu d ies in h y p e r te n s io n . S tu d ie s h av e a ls o b e e n p ro p o se d f o r th e d e te rm in a tio n of m o ly b d en u m an d z in c in c a n c e ro u s t i s s u e s .

4 .6 B ro m in e exchange re a c tio n betw een g a lliu m b ro m id e and ethy l b ro m id e in so lu tio n

T h e ex ch an g e r e a c t io n s b e tw e en g a lliu m b ro m id e and m e th y l b ro m id e o r h y d ro g e n b ro m id e h av e b ee n s tu d ie d p re v io u s ly , an d th is s tu d y i s b e in g e x te n d e d to th e s y s te m g a l l iu m b ro m id é an d e th y l b ro m id e . R a d io a c tiv e g a lliu m b ro m id e is p r e p a re d by d ir e c t co m b in atio n of m e ta l lic g a lliu m w ith r a d io - b r o m in e , an d th e k in e t ic s o f th e ex c h an g e r e a c t io n a r e m e a s u r e d a f t e r d is s o lv in g th e r a d io a c t iv e g a l l iu m b ro m id e in a n o r g a n ic s o lv e n t.

5 . CO N CLU SIO N S

T h e s h o r t- l iv e d ra d io iso to p e s p ro d u ced d u rin g th e fiv e m on ths in w hich th e r e a c to r h a s b een in o p e ra tio n a r e s u m m a riz e d in T ab le I.

In th e fu tu re s h o r t - l iv e d ra d io is o to p e s of h ig h e r sp e c if ic a c tiv ity , and a g r e a t e r v a r ie ty of n u c l id e s , w ill n ee d to b e p ro d u c e d . F o r th is p u rp o s e eq u ip m en t f o r ra d ia tio n sh ie ld in g , such a s J u n io r C aves and m e d iu m -h ea v y glove b o x es , w ill be n e c e s s a r y .

T h e R a d io is o to p e C l in ic s of S eo u l N a tio n a l U n iv e r s i ty , K yongbook M e d ic a l S ch o o l, Suw on A g r i c u l tu r a l C o lle g e , P u s a n M e d ic a l S ch o o l an d

SHORT-LIVED RADIOISOTOPE PRODUCTION, ETC. IN KOREA 225

TABLE I

S H O R T -L IV E D RAD IOISO TO PES PRO D U C ED DURING TH E FIR ST F IV E MONTHS OF O PER A TIO N O F T H E TRIGA MARK II REACTOR

IN KOREA

Nuclide Amount produced (m e)

Amount distributed (m e)

Na24 494 .2 478.86

K42 3 .5 3 .5

Au1* 44 .86 (foil) 41 .740 .99 (colloidal) 0.99

Mo99 4 4

Cu“ 1 1

jl28 1 1

Mn56 1.94 1.94

Br“ 1 .1

w l» 5 4

C hunnam M e d ic a l S choo l a r e w e ll-e q u ip p e d f o r r e s e a r c h and , in th e c a s e of m e d ica l c lin ic s , fo r tr e a tm e n t a lso . Many of the p e rso n n e l in th e se o rgan iz a tio n s h av e b ee n t r a in e d a b ro a d . M any o th e r o rg a n iz a tio n s h av e id e a s f o r th e a p p lic a tio n of ra d io is o to p e s , b u t a t p r e s e n t h av e no in s t ru m e n ts . T h e A to m ic E n e rg y R e s e a r c h In s t i tu te s t im u la te s o th e r in s t i tu te s , u n iv e r s i t ie s an d h o s p ita ls to s tu d y th e f u r th e r a p p lic a b ili ty of th o s e iso to p e s a t p r e s e n t a v a ila b le and a lso th e p o s s ib le u til iz a tio n of o th e r s h o r t- l iv e d ra d io iso to p e s w hich w ill b ec o m e a v a ila b le la t e r .

In th e op in ion of th e a u th o r, fu tu re p la n s fo r a c tiv e u til iz a tio n of s h o r tl iv e d r a d io is o to p e s in K o re a sh o u ld in c lu d e t r a in in g in th e u s e of r a d i o is o to p e s , in c lu d in g in s t ru m e n ta tio n . It i s e x p e c te d th a t in th e fu tu re m o re p ro m p t d e l iv e ry w ill be m a d e to iso to p e u s e r s . A u th o riz e d p e rso n n e l in the f ie ld sh o u ld p e r io d ic a l ly su rv e y th e la b o r a to r ie s in w h ich th e iso to p e s a r e u s e d and th e r e s u l t s w h ich h a v e b ee n o b ta in e d . It is a l s o n e c e s s a r y to s e t up jo in t r e s e a r c h f o r th e ex ch an g e of id e a s and f o r b e t te r u n d e rs ta n d in g of in te r r e la t e d f ie ld s .

R E F E R E N C E S

[1] GENERAL ATOMIC, TRIGA MARK II Reactor Description, GA-568 (1960) 1-22.[2J STROMÏNGER, O ., HOLLANDER, J .M . and SEABORG, G .T . . Table o t Isotopes, Rev.mod.Phys. 30 (1958). |3 J HUEDLANDER, G. and KENNEDY. J . W . , N uclear and Radioctiem istry, John W iley & Sons (1957) 332.

226 CHONG KUK KIM

D I S C U S S I O N

A . S E L L E R IO : C ould you g ive so m e d e ta i ls on th e m e th o d s u se d fo r lo c a liz in g th e le a k a t th e K ihung ir r ig a t io n r e s e r v o i r ? I g a th e r th a t d igg ing w a s c a r r i e d out and sa m p le s ta k en in the g round , o r w e re s u r fa c e sa m p le s ta k e n ?

C . K . K IM : N o d ig g in g w a s c a r r i e d o u t. W e co u ld s e e th e le a k o u tle t an d a g e o lo g ic a l s tudy in d ic a te d th a t th e le a k in le t w a s lo c a te d abou t 80 m f ro m th e po in t w h e re th e dam m e e ts a m o u n ta in n e a r th e s h o re lin e . A ll we d id w as to d ro p 10 to 15 m e of N a24 in to the r e s e r v o i r a t 50 -m in te rv a ls and m e a s u re lyith a sc in til la tio n co u n te r .

R . LOOS:, You a ls o c a r r i e d out i r r a d ia t io n s of am m o n iu m m o ly b d a te . In m y p a p e r ( th e se p ro c e e d in g s ) I m en tio n e d tw o p ro b le m s a s s o c ia te d w ith ir r a d ia t io n of th e m o lybda te , n am ely the p re s e n c e of ra d io a c tiv e im p u r it ie s a n d m o d if ic a tio n of c h e m ic a l f o rm . D id you s tudy th e s e p ro b le m s ?

C . K . KIM : No, we d id n o t. W e took an a n a ly tic a l g ra d e of am m o n iu m m o ly b d a te , w;hose r a d io c h e m ic a l p u r i ty w a s a d e q u a te f o r u s e r s in K o re a . I do no t th in k s h o r t - t im e ir r a d ia t io n g iv e s any s ig n if ic a n t co n ta m in a tio n to in te r f e r e w ith th e m e a s u re m e n t of Moaa.

H . SORANTIN: In se c tio n 2 of y o u r p a p e r you m en tio n th a t c o p p e r w as d is so lv e d in c o n c e n tra te d H Cl. C opper d is so lv e s v e ry slow ly in h y d ro ch lo ric a c id , ex c ep t f o r v e ry s m a ll q u a n titie s w ith a g re a t s u rp lu s of a c id . I w ould lik e to know in w hat fo rm you have been ir ra d ia t in g C opper—pow der o r so lid — an d w hat am o u n ts of c o p p e r you m anaged to d isso lv e .

C . K . KIM: W e u se d bo th c o p p e r m e ta l po w d er and c u p r ic n i t r a te (an a ly t ic a l g ra d e ) a s th e ta r g e t m a te r ia l f o r c o p p e r-6 4 p ro d u c tio n . T h e c u p r ic n i t r a te w as d is s o lv e d in d is t i l le d w a te r; c o p p e r m e ta l pow der i s v e ry ea s ily d is so lv e d in h y d ro c h lo r ic ac id , and we took only a v e ry sm a ll am ount, about 10 m g, and i r r a d ia te d fo r 5 to 7 h .

F . N ELSO N : I w ould l ik e to m ak e a c o m m en t on th e l a s t q u e s tio n . T h e rm o d y n a m ic a lly , c o p p e r should not d is so lv e in d ilu te h y d ro c h lo r ic ac id , an d I th in k th a t in th is c a s e p e rh a p s the s m a ll am oun t ôf a i r p r e s e n t in th e so lu tio n a s s i s t s th e d is s o lu tio n .

C . K . KIM: We should d isso lv e copper in n itr ic ac id r a th e r than in h y d ro - c h lo r ic , b u t m o s t of th e u s e r s in K o re a w an t th e c h lo r id e f o r m , an d th e a m o u n t w e a r e d e a lin g w ith i s so s m a l l th a t t h e r e i s no d if f ic u lty .

C . TA Y LO R : I s e e f ro m th e s a m e se c tio n of y o u r p a p e r you h av e i r ra d ia te d c o llo id a l gold to m ake go ld-198 . I would like to a sk fo r what pu rpose i t w a s u se d , and a ls o w h e th e r you n o tic e d any c o a g u la tio n of th e c o llo id a l g o ld a f te r i r r a d ia t io n .

C .K . KIM: W e u se d th e re a d y -m a d e USP (United S ta te s P h a rm ac y ) c o llo id a l gold fo r th e ta r g e t . T he p re p a ra tio n w as d es ig n ed m ain ly fo r m e d ica l p u rp o se s . T h e re w as no coagu la tion , it looked exac tly the sam e a s the ta rg e t m a te r ia l .

Ill

INDUSTRIAL APPLICATIONS

SHORT-LIVED ISOTOPES USED AS TRACERS IN INDUSTRY

(WITH SPECIAL REFERENCE TO SWEDISH INDUSTRY)

L. G. ERWALL, H. G. FORSBERG AND K. LJUNGGREN ISOTOPTEKNISKA LABORATORIET, STOCKHOLM, SWEDEN


SHORT-UVED ISOTOPES USED AS TRACERS IN INDUSTRY (WITH SPECIAL REFERENCE TO SWEDISH INDUSTRY). Radioactive tracer methods are rapidly being recognized as a valuable means in industrial research and contro l. They have already been used w ith g rea t advantage in trouble shooting, in investigations of the characteristics of process units and as an a id in designing such units.

This review comprises typ ica l exam ples of applications o f short-lived tracers, which can be produced in m edium neutron fluxes, for exam ple, Na24, Cl**, K42, Mn56, Br82, La140 and AvP* ; studies of the transport of solids through process units — rotary kilns, blast furnaces, cellulose digesters, blea ching towers, dorr- thickeners ; d e term ination of flow rates for liquids in tubes and open stream s, to m easure, for exam ple, the to ta l w ater consumption in a plant; determ ination of residence tim es, hold-back and blocked volume for liquids indifferent process units, for exam ple in the pulp and paper industry; "weighing" by means of isotope dilution techniques for de te rm ina tion of the am ount of slag in open-hearth furnaces, e tc . ; d e te rm ina tion of the origin o f non- m e ta llic inclusions in s tee l to find b e tte r lining m ateria ls and to op tim ize pouring techniques; labelling for quality identification »- experim ental s teel baths and specific m ateria l in the iron and steel industry are being identified with absolute certain ty ; determ ination of the efficiency of mixers in the concrete industry; mapping of flow in receivers for sewage or waste water to find the best point for the outlet of such liquids; and detection and localization of leaks.

To m in im ize the con tam ination of the final products, the av a ilab ility o f short-lived tracers has been essential in many of these studies. Most cases are of the physical tracing type, with a variety of possible tracers. Thus a trace r can be chosen w hich has a su itab le ha li~ lite and rad ia tion characteris tics. If the rad ioac tive nuclide used has a large neutron activation cross-section, which is the case for the above-m entioned nuclides, a research reacto r has sufficient neutron flux for the production o f quantities o f even curies o f the tracers, providing th a t high specific a c tiv ity is not a requisite.

In Sweden a jo in t industrial institu te , the Isotope Techniques Laboratory, was formed in 1960 to m ake research and developm ent work and to assist the industrial enterprises with adv ice, personnel and instruments necessary in industrial radioisotope application .

EMPLOI DE RADIOINDICATEURS DE COURTE PÉRIODE A L'ÉCHELLE INDUSTRIELS DANS LES USINES SUÉDOISES. Les m éthodes reposant sur l ’em p lo i de radioindicateurc jouen t, dans les travaux d e recherche e t les opérations de contrô le industriels, un rôle dont on reconnaît de plus en plus l 'u t i l i té . On les em plo ie avan tageusem ent pour dép ister les défauts e t avaries, pour analyser les caractéristiques des installations de tra item en t e t pour l 'é tu d e de ces installations.

Les auteurs donnent des exem ples typiques d 'applications de radioisotopes de courte période qui peuvent ê tre produits par des flux de neutrons de m oyenne in tensité, par exem ple: 24N a, й Мп, 82Br, 140 La, 38С 1,42K e t 198 Au.

On trouvera c i-aprês quelques exem ples de ces études:Etudes sur le m ouvem ent des solides dans des installations de tra item ent - fours rotatifs, hauts fourneaux,

digesteurs â cellu lose , tours de b lanch im ent, épaississeurs Dorr; dé te rm ination du déb it de liquides dans des canalisations e t â découvert, par exem ple, pour m esurer la quan tité to ta le d 'e a u consom m ée par une p lante ; déterm ination des tem ps de séjour, de la rétention e t du volum e bloqué de liquides â divers stades de la fabrication du papier e t de la pâte à papier, par exem ple; « p e sa g e » par les méthodes de d ilution isotopique, en vue de dé te rm iner la quan tité de scories dans les fours â sole; dé term ina tion de l'o rig in e des inclusions non m étalliques dans l 'a c ie r , en vue de l'ob ten tion de m eilleurs m atériaux de revêtem ent e t du perfectionnem ent des m éthodes de cou lée; m arquage aux firs de con trô le de la qua lité , p rocédé perm ettan t d 'id e n tif ie r avec une certitude absolue des bains d 'a c ie r d 'expérim entation e t certains autres produits de l'industrie sidérurgique;

229

230 L. G. ERWALL et al.

déterm ination de l 'e f f ic ac ité des m élangeurs dans l'industrie du béton; é tude de l ’écoulem ent dans les fosses récép trices d 'e au x usées en vue de découvrir le m e ille u r point d ’évacuation ; d é tec tio n e t loca lisa tion des fuites.

Dans beaucoup de ces études, l'u tilisation d ’indicateuts de courte période a é té indispensable pour réduire au m inim um la con tam ination du produit final. Dans la plupart des cas, i l s 'a g it d 'u n m arquage purem ent physique â l 'a ide de divers indicateurs possibles. On peut ainsi choisir un indicateur ayant une période appropriée e t les caractéristiques de rayonnement voulues. Si le radionucléide utilisé présente une grande section efficace pour l ’activation par les neutrons - ce qui est le cas des nucléides énum érés plus hau t - un réacteu r de re cherche aura un flux de neutrons suffisant pour produire des activ ités de l ’ordre de plusieurs curies, â moins que l ’on a i t besoin d ’une forte a c tiv ité spécifique.

En Suède, un institu t industriel m ix te , le Laboratoire des méthodes isotopiques, a é té créé en 1960 e t chargé de faire des travaux de recherche e t de m ise au point, e t d ’a ider les entreprises industrielles en leur donnant leá conseils, le personnel e t les appareils dont e lles ont besoin pour appliquer les méthodes u tilisant les radioisotopes.

ПРИМЕНЕНИЕ КОРОТКОЖИВУЩИХ ИЗОТОПОВ В ПРОМЫШЛЕННОСТИ В КАЧЕСТВЕ МЕЧЕНЫХ АТОМОВ. Методы радиоактивных меченых атомов быстро находят свое признание как неоценимое средство для исследований и контроля в промышленности. Они ухе успешно применялись в аварийных случаях, при исследовании характеристик производственных узлов и как вспомогательное средство при конструировании таких производственных узлов.

Данный обзор содержит типичные примеры применения короткоживущих меченых атомов, которые могут быть получены в умеренных нейтронных потоках, например,натрия-24, магния-56, брома-62, лантана-140, а также хлора-38, калия-42 и золота-196. С помощью короткоживущих изотопов можно производить:- изучение прохождения твердых веществ через производственные узлы

(вращающиеся сушильные печи, доменные печи, целлюлозные автоклавы, башни для отбелки, сгустители Дорра) ;

- определение^скорости потока жидкостей в трубах и в открытых руслах(например, для измерения общего количества потребления воды на установке);

- определение времени нахождения задержки и объема жидкостей в различных технологических узлахв целлюлозной и бумажной промышленности;

- "взвешивание" по методу изотопного разбавления для определения количества шлаков в мартеновскихпечах;

- определение происхождения неметаллических примесей в стали для изыскания лучших материалов дляоблицовки и для усовершенствования методов отливки;

- мечение для определения качества, позволяющее установить с абсолютной достоверностью экспериментальные стальные плавки и специфические материалы в черной металлургии;

- определение эффективности месилок в бетонной промышленности;- составление диаграмм потока в бассейнах для сточных вод или жидких отходов в целях нахождения

наилучшего места для спуска таких жидкостей;- обнаружение утечек.

Чтобы свести к минимуму загрязнения окончательных продуктов при проведении многих из этих исследований, было существенно важно использовать короткоживущие меченые атомы. В большинстве случаев применялись методы физического мечения с возможностью выбора самых разнообразных меченых атомов. Тем самым представляется возможным выбирать меченые атомы с подходящим полупериодом распада и с нужными характеристиками излучения. Если используемый радиоизотоп обладает большим сечением активации нейтронов, что присуще перечисленным выше изотопам, то исследовательский реактор может дать достаточный поток нейтронов для производства активностей индикаторов порядка до нескольких кюри при условии, что не требуется для них значительной удельной активности.

В Швеции в 1960 году был образован объединенный промышленный институт и лаборатория изотопных методов для проведения исследований и работ по развитию, а также для оказания помощи промышленным предприятиям посредством предоставления консультаций, персонала и необходимых приборов по промышленному применению радиоизотопов.

ISÓTOPOS DE PERÍODO CORTO UTILIZADOS GOMO INDICADORES EN LA INDUSTRIA SUECA. Rápida- m en te se va reconociendo que los métodos basados en e l em pleo de indicadores radiactivos son muy valiosos

SHORT-LIVED ISOTOPES USED AS TRACERS IN INDUSTRY 231

en la investigación y e l control industriales. Se han u tilizado ya con gian éxito para lo ca liza r defectos, estu d ia r las c arac te rís ticas de insta laciones industriales y com o ayuda para d iseñar d ichas insta lac iones.

La presente m em oria c ita ejem plos típicos de las aplicaciones de los indicadores de período corto que se pueden obtener con flujos neutrónicos m edios, por e jem plo , ^ N a .^ C l , *£K, 0bM n,e¿Br, 14üLa y 198Au: Estudio del transporte de sólidos en instalaciones industriales (hornos giratorios, altos hornos, digestores para celulosa, torres de b lanqueo, espesadores Dorr); de term inación d e l caudal de líquidos en tuberías y canales abiertos, por e jem plo , para m edir e l consumo to ta l de agua en una fábrica; determ inación de tiem pos de perm anencia y de volúmenes bloqueados para líquidos en diversas instalaciones, por ejem plo , en las industrias de la pulpa y del papel;"determ inación de pesos" por m edio de técnicas de dilución isotópica, por ejem plo , para evaluar la cantidad de escoria presente en hornos de hogar abierto; determ inación del origen de inclusiones no m etálicas en e l acero, para perfeccionar revestimientos y hallar las técnicas óptimas de colada; marcación para identificar la calidad (en las industrias d e l hierro y d e l acero se están iden titicando con certeza absoluta bafios experim entales y m ateriales específicos); determ inación del rendimiento de mezcladoras en la industria delhoim igón; determ inación de las corrientes en tanques receptores de aguas servidas con m iras a encontrar e l lugar óptimo para la boca de salida de l líquido; y detección y localización de fugas.

Los indicadores de período corto han sido esenciales en muchos de estos estudios para reducir a un mínim o la contam inación del producto final. En la m ayoría de los casos, la m arcación es física , pudiendo elegirse e l indicador de forma que su periodo de sem idesintegración y las características de las radiaciones que em iten sean adecuados. Si e l núclido radiactivo que se em plea tiene una elevada sección eficaz de activación neu- trónica , como es e l caso de los nüclidos m encionados, e l flujo neutrónico de un reactor de investigación basta para obtener indicadores de algunos curies de ac tiv id ad , siem pre que no sea im prescindible una ac tiv id ad específica e levada.

En I960 se creó en Suecia un institu to industrial c en tra l, e l Laboratorio de T écn icas Isotópicas, cuya misión es llevar a cabo trabajos de investigación y desarrollo y prestar asistencia a las em presas industriales proporcionándoles aseso iam ien to , personal y los instrum entos necesarios para las ap licac io n es industriales de los radioisótopos.

1. INTR O D U C TIO N

T fte adven t oí n u c le a r r e á c to r s and th e dev e lo p m en t o f h ig h ly -se n s itiv e m e a s u r in g eq u ip m en t fo r n u c le a r ra d ia t io n h a s m a d e p o s s ib le th e d ev e lo p m e n t of b e n e f ic ia l u s e s o f r a d io is o to p e s a s t r a c e r s in in d u s t r ia l r e s e a r c h and c o n tro l . In m an y su c h s tu d ie s th e ch o ice of th e ra d io a c tiv e n u c lid e ca n b e m a d e f ro m a l a r g e n u m b e r of p o s s ib le t r a c e r s (p h y s ic a l t r a c in g ) bu t in so m e c a s e s i t is n e c e s s a r y to ch o o se a ra d io a c t iv e iso to p e o f a g iv en e l e m e n t (ch e m ic a l tr a c in g ) . W hen ch o o s in g a ra d io a c tiv e t r a c e r fo r a c e r ta in a p p lic a tio n , th e g e n e ra l r u le is th a t th e t r a c e r shou ld be a s s h o r t - l iv e d as p o s s ib le ; one r e a s o n fo r th is i s th e n e c e s s i ty of av o id in g lo n g - la s tin g c o n ta m in a tio n of p ro d u c ts , w hich could c r e a te a h a z a rd fro m th e ra d ia tio n p ro te c tio n po in t of v iew , but could a lso be d isad v an tag eo u s if the m a te r ia l p ro d u c e d i s to be u se d in , e . g . , c a s s e t t e s fo r p h o to g ra p h ic f i lm , o r h o u s in g , o r s h ie ld s fo r n u c le a r r a d ia t io n d e te c to r s .

T h e p ro m o tio n of th e in d u s t r ia l u s e s of ra d io iso to p e s as t r a c e r s should th u s in c lu d e th e c re a tio n of p ro d u c tio n fa c i l i t ie s fo r s h o r t- l iv e d t r a c e r s not to o fair d is ta n t f ro m th e m a jo r p o te n t ia l u s e r s of su c h m a te r i a l . In m a n y c o u n tr ie s b u ild in g r e s e a r c h r e a c to r f a c i l i t i e s sh o u ld m ak e i t e a s ie r fo r in d u s t r y to ta k e ad v a n ta g e of th e p o s s ib i l i t i e s o f fe re d by r a d io a c t iv e - t r a c e r te c h n iq u e s . In th e ch o ice of a p h y s ic a l t r a c e r no t on ly th e h a l f - l if e and th e r a d ia t io n c h a r a c t e r i s t i c s sh o u ld b e ta k e n in to c o n s id e r a t io n , b u t a ls o th e n eu tro n c r o s s - s e c t io n fo r the p ro d u c tio n of the t r a c e r . S e v e ra l o f th e t r a c e r s s u c c e s s fu l ly u s e d in th e in v e s tig a tio n s r e p o r te d in th is re v ie w w e re m a d e w ith iso to p e s w hich ca n b e ob ta in ed in h igh sp e c if ic a c tiv i tie s by i r ra d ia t io n


in a r e a c to r w ith a m o d e ra te n e u tro n flu x . In f a c t , th e n e u tro n f lu x f ro m an a c c e le r a to r m a y a ls o b e su f f ic ie n t to p ro d u c e so m e o f th e s e t r a c e r s in a m o u n ts l a r g e en o u g h f o r a f u l l - s c a le te c h n ic a l t r a c e r in v e s t ig a t io n .

M any ra d io a c t iv e t r a c e r m e th o d s a r e g e n e ra l ly a p p lic a b le in in d u s try , i r r e s p e c t iv e of th e b ran c h , and th is h o r iz o n ta l c h a r a c te r of iso to p e tech n iq u es m a k es it d e s ira b le to p re s e n t th e v a r io u s m ethods in re la tio n to the phenom en a b e in g s tu d ie d , and no t in r e la t io n to th e in d u s t r ia l b ra n c h in w h ich th e y m a y h av e b een d ev e lo p ed and th e f i r s t ap p lic a tio n r e a l iz e d . A s f a r a s p o s s ib le th is re v ie w p r e s e n ts ra d io is o to p e t r a c e r te c h n iq u e s d iv id ed in to p h e n om eno log ica l g ro u p s but th e ex am p les given d e s c r ib e app lica tions in sp ec ific b ra n c h e s of in d u s try . T h e r e a d e r o f l i t e r a tu r e on iso to p e te ch n iq u e s should b e a w a re o f th e h o r iz o n ta l c h a r a c t e r o f th e m e th o d s d e s c r ib e d and n o t be d e t e r r e d b e c a u s e an e x a m p le o f an a p p l ic a tio n o f r a d i o t r a c e r s i s th a t of an in v e s tig a tio n p e r fo rm e d in a b ra n c h of in d u s try w hich i s c o m p le te ly d if f e r e n t f ro m h is own.

2. TR A N SPO R T O F SOLIDS AND LIQUIDS

2 .1 . S tu d ies of th e t r a n s p o r t of so lid s ,

T h e tw o m a jo r ad v a n ta g es of ra d io a c tiv e t r a c e r s , co m p a re d w ith o th e r p o s s ib le t r a c e r s , a r e th e e x t r e m e ly s m a l l a m o u n ts o f m a t te r n e c e s s a r y an d th e a b i l i ty o f y - r a d ia t io n to p e n e t r a te . T h e f i r s t m a k e s i t p o s s ib le to p e r f o r m an in v e s tig a tio n by ad d in g a t r a c e r in a m o u n ts s o s m a l l th a t no c o n c e n tra tio n g ra d ie n ts w ill o c c u r w hich could in te r f e re w ith th e n o rm a l p r o c e s s . T h e se c o n d a llo w s , f ro m o u ts id e , m e a s u r e m e n t of th e a c tiv i ty ,i . e . c o n c e n tra t io n of th e t r a c e r , w ithou t in tro d u c in g in to th e p r o c e s s any m e a su r in g d ev ice w hich could d is tu rb th e flow of m a te r ia l . F o r th e s e r e a s o n s , s tu d ie s of th e t r a n s p o r t of so lid s th ro u g h p ro c e s s u n its of v a r io u s k inds can b e m ade w ith g r e a t s u c c e s s .

In r o t a r y K ilns in th e c e m e n t in d u s t ry th e t r a n s p o r t r a t e fo r r a w m a t e r i a l in v a r io u s p a r t s o f th e p la n t h a s b ee n a c c u r a te ly d e te rm in e d [1, 2, 3]. A s m a ll am o u n t of la b e lle d m a te r ia l w as in tro d u c e d a t th e in le t o f th e k iln and th e t im e of a r r i v a l o f th e t r a c e r a t v a r io u s p o in ts w as d e te rm in e d by d e te c to rs m oun ted o u ts id e th e k iln . In one c a s e , th e ra w m a te r ia l con ta ined a c e r ta in p e rc e n ta g e of p o ta s s iu m and th e m a in a im of th e in v e s tig a tio n w as to s tu d y th e b e h a v io u r o f th e p o ta s s iu m . F o r th is r e a s o n so m e k i lo g ra m s o f r a w m a te r i a l w e re la b e l le d by th e a d d itio n o f a w a te r s o lu t io n of a K 4i s a l t . T h e t r a n s p o r t w as fo llow ed a s m e n tio n ed and, fu r th e r m o re , s c in t i l la t io n d e te c to r s m o u n te d on th e c h im n e y s of th e p la n t p ro v id e d in fo rm a tio n r e g a rd in g th e p o ta ss iu m c o n c e n tra tio n in th e g a s e s leav in g th e fu rn a ce . T he r e s u l t s o f th e in v e s t ig a t io n , show n in F ig . 1, r e v e a le d th a t th e p o ta s s iu m ev a p o ra te d in th e v e r y l a s t p a r t o f th e fu rn a c e and fo llow ed th e g a s e s b ack th ro u g h th e fu rn a c e and in to th e h ea tin g c h a m b e rs . H ere th e p o ta ss iu m cond e n s e d and e v id e n c e w as th e re b y g a in ed th a t so m e d if f ic u lt ie s in th e o p e r a t io n o f th e f u rn a c e co u ld b e r e l a t e d to th e s u b l im a t io n o f p o ta s s iu m .

In b la s t fu rn a c e s and con tinuous c e llu lo se d ig e s te r s th e t r a n s p o r t r a te fo r in d iv id u a l p ie c e s of m a te r i a l th ro u g h th e p r o c e s s u n it h a s b ee n d e t e r m ined . T agged p ie c e s w ere in tro d u ced in to th e in le t of th e un it, and d e tec to rs

SHORT-UVED ISOTOPES USED AS TRACERS IN INDUSTRY 233

COUNT RATE AT AUXILIARY CHIMNEY

F ig .l

Above. Diagram of cem ent plant with the position of the detectors in the reported investigation shown. The established recirculation of potassium has been indicated in the figure.

Below. D iagram of the transport of labelled m ateria l in the cem ent p lan t. The position of the m ateria l a t d ifferent tim es and the speeds in the different zones are shown together with the sim ultaneously-recorded

counti-rate in the auxiliary chim ney and in the heating cham bers.

a t th e in le t and o u tle t r e g is t e r e d th e ac tiv ity con tinuously . T h e t im e of a r r iv a l and d e p a r tu re fo r e a c h in d iv id u a l p ie c e w as d e te rm in e d by th is m e th o d . In a c e l lu lo s e d ig e s te r , F ig . 2, th e ta g g e d c h ip s o f w ood w e re a ls o fo llo w ed d u r in g th e i r p a s s a g e th ro u g h th e d ig e s te r b y m e a n s o f a p o r ta b le s c in t i l la t io n c o u n te r m e a s u r in g th e a c tiv ity a t v a r io u s p o in ts o u ts id e th e d ig e s te r [4, 5]. T h is m ade it p o ss ib le to d e te rm in e th e tim e when each ind iv idual p iece a r r iv e d a t c e r ta in p o in ts ancL also to c a lc u la te , f ro m th e a tte n u a tio n o f th e ra d ia tio n , th e d is ta n c e f ro m th e w all of each tag g ed p ie ce a t each m e a su r in g


CHIPS IN THIS AREA CANNOT BE DETECTED

DIGESTER

WOOD CHIP № 1

J CROSS-SECTION

1 2 h 1 min2 A 2 h 1 min3 ° 2 h 1 min 40s4 о 2h 2 min 15s5 « 2 h 5 min

RETENTIONTIME

120 ( min)

Distance plo tted against tim e for labelled chips moving down a continuous digester. Position in thecross-section is ind icated .

po in t. A s can be se e n f ro m th e f ig u re , ch ip s m oving along d iffe re n t v e r t ic a l l in e s m o v ed a t th e s a m e sp e e d a l l th e w ay th ro u g h th e d ig e s te r .

In th e m e ta l lu rg ic a l in d u s try , r a d io a c tiv e t r a c e r s have b ee n s u c c e s s fu lly a p p lie d to s tu d ie s o f th e t r a n s p o r t o f so lid m a te r i a l th ro u g h p r o c e s s u n its , e . g. b la s t fu rn a c e s o r cu p o la fu rn a c e s . S e v e ra l in v e s tig a tio n s a r e r e p o r te d u s in g t r a c e r s w ith a m e d iu m h a l f - l i f e , su c h a s P 32, F e 59 and C e141. S h o r t- l iv e d t r a c e r s , su c h a s m e ta l l ic Au198 and L a 140 a s o x id e , h av e b e e n u s e d to s tu d y th e t r a n s p o r t o f i r o n - s c r a p and co k e r e s p e c t iv e ly [6 ]. T h e l a t t e r t r a c e r s have a ls o b ee n u se d in r e c e n t in v e s tig a tio n s in Sw eden. One in v e s tig a tio n w as to d e te rm in e th e t r a n s p o r t r a t e th ro u g h a cu p o la fu rn a c e f o r s c r a p - i r o n , co k e and l im e - s to n e , r e s p e c t iv e ly . S m a ll c o n ta in e r s o f iro n , co n ta in in g an i r r a d ia te d m ix tu re of la n th an u m oxide and s la g fo rm in g a m ix tu re of c a lc iu m and a lu m in iu m s i l ic a te s , w ere p la ce d in h o le s in coke lu m p s and in w e lls in p ie c e s -o f s c r a p - i r o n . T h e c o n ta in e rs had b ee n g iven a s h o r t i r r a d ia t io n in a n u c le a r r e a c to r and w e re le f t fo r abou t one d ay to a llo w s h o r t - l iv e d is o to p e s of s i l ic o n and m a n g a n e s e (p re s e n t in th e i r o n c o n ta in e r ) to d e c a y ; Lai40 g av e a t l e a s t 99% of th e to ta l y - a c t iv i ty of th e c o n ta in e r 40 h a f te r th e i r r a d ia t io n . T h e w ells in th e s c r a p - i r o n w e re p lu g ged w ith a s c re w and w elded , and th e coke lu m p s w ere p lugged w ith f ire c la y p a s te . T he ta g g e d p ie c e s w e re added to th e top of th e fu rn a c e . T h e p ig - ir o n and s la g w e re co n tin u o u sly p o u re d out of th e fu rn a c e and th e a c tiv ity of th e s la g w as d e te rm in e d in s a m p le s ta k e n a t th e o u tle t a t in te r v a ls of a p p ro x im a te ly one m in u te . T h e r e s u l t s f ro m an in v e s tig a tio n in c lu d in g m e a s u r e m e n ts w ith a 1 inX 1 in s c in ti l la t io n c r y s ta l on 125 cm* s a m p le s a r e show n in F ig . 3. D ue to th e k in e tic s of th e m ix in g in th e s la g b a th , th e a c tiv i ty of th e s a m p le s in c r e a s e s c o n tin u o u s ly a t th e b eg in n in g , bu t th e t im e f o r th e

SHORT -LIVED ISOTOPES USED AS TRACERS IN INDUSTRY 235

TIME (m in)

Fig.3

Count-rate for samples taken from the slag phase and the m eta l In a cupola furnace. A p iece of scrap tagged with LaM0 and Au158 had been introduced a t the top o f the furnace a t 08. 05 .

-------- the slag phase ( Ln^° )------- the m etal (Au1® )

The average residence tim es calcu lated from the curves i

in the slag phase: 1 h 43 min in the m e ta lj 22 m in .

a r r i v a l o f th e s o u r c e a t th e b a th c a n b e d e te r m in e d w ith g h ig h d e g re e of a c c u ra c y by e x tra p o la tio n of th e a c tiv ity c u rv e . A s a s e c o n d a ry r e s u l t , th e a v e r a g e r e s id e n c e t im e in th e s la g b a th co u ld b e d e te rm in e d an d , w ith a know ledge of th e a v e rag e s la g flow , th e am ount of m o lten s la g in th e fu rn ace w as c a lc u la ted .

F u r th e r in v e s tig a tio n s w e re m a d e w ith bo th la n th a n u m ox ide and gold m e ta l i r r a d ia te d in th e s a m e c o n ta in e r . I t w as p o s s ib le to d e te r m in e , in ad d itio n , th e a v e ra g e r e s id e n c e t im e fo r th e liq u id p ig - i r o n and th e t r a n s p o r t t im e of th e m o lte n i r o n th ro u g h th e s la g b a th fo r th e s e in v e s tig a tio n s , an im p o r ta n t m e a s u r e m e n t f ro m th e m e ta l lu r g i c a l p o in t o f v ie w .

In co n c lu d in g e x p e r im e n ts th e t r a n s p o r t r a t e s f o r co k e or s c r a p - i r o n w e re c o m p a re d w ith th o s e fo r i r r a d ia te d l im e -s to n e lu m p s . W hen th e Leí40

and Au198 a c t iv i t ie s in th e s a m p le s had d e c a y e d , c a lc iu m w a s s e p a r a te d c h e m ic a l ly and Ca45 d e te rm in e d by liq u id s c in t i l la t io n co u n tin g o r coun ting w ith an end -w in d o w G M -tu b e s u r ro u n d e d by an a n t i- c o in c id e n c e u m b r e l la sh ie ld .

O th e r m e ta l lu rg ic a l fu rn a c e s h av e a ls o b e e n s tu d ie d , e . g. a W ib e rg - S o d e rfo rs fu rn a c e fo r re d u c in g i r o n - o r e c o n c e n tra te s [7]. T h e s in te re d o re e n te r s th e fu rn a c e a t th e top a p i i s re d u c e d w ith c a rb o n m onoxide e n te r in g f ro m th e b o ttom . T agged ch am o tte b a lls of th e sa m e s iz e as the s in te r w ere in tro d u c e d in d if fe re n t p la n e s and a t d if fe re n t d is ta n c e s , f ro m th e w a ll and th e tim e of a r r iv a l a t th e ou tle t fo r th e se b a lls w as d e te rm in e d w ith a s c in tilla t io n d e te c to r . T h e th r e e b a l ls in on e an d th e s a m e p la n e h ad d i f f e r e n t a c t iv i t ie s and th is m ad e i t p o s s ib le to id e n tify th e b a l ls f ro m th e p e a k s r e g is te re d on the r e c o rd e r . F ig u re 4 show s th e r e s u l t s of one of th e se in v e s tig a tio n s ; th e d if fe re n c e in t im e fo r th e th r e e b a l ls in th is c a s e w as r e la te d to th e c o n s tru c tio n of the bo ttom p a r t of th e fu rn a ce and ca lc u la tio n s show ed


Fig .4

The recorder diagram shows the appearances of three labelled pellets a t the ou tle t of a sponge iron furnace.Pellets from three different positions a t one level in the furnace are recorded.

th a t th e t r a n s p o r t r a t e in th e c y l in d r ic a l p a r t of th e fu rn a c e w as id e n t ic a l fo r аП th e b a l ls .

In th e s u g a r in d u s t ry im p u r i t ie s a r e re m o v e d f ro m s u g a r so lu tio n by c o - p r e c ip i ta t in g th e m w ith c a lc iu m c a rb o n a te by th e ad d itio n of c a rb o n d io x id e . T h e s l u r r y th e n g o e s th ro u g h a th ic k e n e r w h e re th e s o lid p h a s e s e t t le s and a c le a r so lu tio n i s ob ta ined a t th e top . T h e flow of bo th th e so lid and liq u id p h a s e s in su c h th ic k e n e r s h a s b e e n s tu d ie d by add ing a p h y s ic a l t r a c e r [8]. T h e w a te r p h a se w as la b e lle d w ith a so d iu m s a l t , and th e s lu r r y w ith a la n th a n u m s a l t , w h ich p r e c ip i t a t e s a s h y d ro x id e a t th e pH in th e so lu tio n . T h e t r a c e r s w e re m o m e n ta rily added and the a c tiv ity a t the o u tle ts fo r th e c o n c e n tra te d s l u r r y and fo r th e c l e a r so lu tio n w as m e a s u r e d c o n t in u o u s ly w ith s c in t i l la t io n c o u n te r and r e c o r d e r . T h e in v e s tig a tio n gave v a lu a b le in fo rm a tio n on th e d is t r ib u t io n of th e s o l id p h a s e in th e v a r io u s p a r t s o f th e th ic k e n e r .

2 . 2 . D e te r m in a t io n o f r e s id e n c e t im e s , h o ld -b a c k an d b lo c k e d v o lu m e

I t i s o f ten of c o n s id e r a b le i n t e r e s t to d e te r m in e flow c h a r a c t e r i s t i c s in a r e a c t io n v e s s e l in o r d e r to c o m p a re th e m w ith th o s e in te n d e d by th e d e s ig n in g e n g in e e r . A m o m e n ta ry a d d itio n o f a r a d io a c t iv e t r a c e r in th e in le t o f th e v e s s e l , com bined w ith continuous m e a su re m e n t of i t s c o n c e n tra t io n in th e o u tle t , c a n r a p id ly and e a s i ly show th e c h a r a c t e r o f th e flow in th e v e s s e l , and a lso w h e th e r o r not th e to ta l vo lum e of th e v e s s e l is e ffe c tiv e ly r e p le n is h e d by th e th ro u g h flow . T h e a v e ra g e r e s id e n c e t im e in th e v e s s e l c a n b e d e te r m in e d f ro m a c u rv e of th e a c tiv i ty a s a fu n c tio n of th e t im e , m e a s u re d a t th e o u tle t. If th is tim e is c o n s id e ra b ly s m a l le r th a n th a t e x p e c ted (i. e . th e to ta l vo lum e of th e v e s s e l d iv ided w ith th e flo w -ra te ) th is in d ic a te s th a t a c o r re s p o n d in g p a r t o f th e v o lu m e i s on ly s lo w ly o r n o t at a l l r e p le n is h e d . T h e sh a p e of th e a c tiv i ty p lo tte d a g a in s t th e t im e c u r v e a t th e o u tle t a ls o in d ic a te s d e ta i l s of th e flow th ro u g h th e v e s s e l . T w o ex t r e m e c a s e s a r e found — f i r s t ly , w hen th e in c o m in g liq u id is im m e d ia te ly m ix ed hom ogeneously in th e to ta l vo lum e of th e v e s s e l , and seco n d ly , when aH liq u id e le m e n ts e n te r in g th e v e s s e l a t a g iv e n t im e m o v e th r o u g h th e v e s s e l a long p a r a l le l p a th s and le a v e th e v e s s e l a t one and th e s a m e t im e . T h is se co n d c a s e i s known a s " p is to n flo w ". In p r a c t ic e p r o c e s s u n its a r e u s u a lly d e s ig n e d to g iv e one o f th e s e tw o flow c h a r a c t e r i s t i c s but in o p e r


a tio n th e y show c h a r a c t e r i s t i c s b e tw een th e s e tw o e x tre m e c a s e s . T h e d e g r e e of m ix in g c a n b e q u a n t i ta t iv e ly d e te r m in e d u s in g th e f o r m a l i s m developed by DANCKW ERTS [9]. It should be no ted , ho w ev er, th a t acco rd in g to D a n c k w e rts , th e a v e ra g e r e s id e n c e t im e found e x p e r im e n ta lly i s a lw ays eq u a l to th e e x p e c te d t im e , but th is i s se ld o m th e c a s e in p r a c t ic e , due to th e lim ite d s e n s itiv i ty of the m e a su r in g m ethod: sm a ll t r a c e r co n c en tra tio n s , r e s u l t in g f ro m a d if fu s io n of t r a c e r in to s ta g n a n t p a r t s of th e v e s s e l , w ill n e v e r b e d e te c te d . I t h a s t h e r e f o r e b e c o m e c u s to m a r y to p r e s e n t , a s in F ig . 5, th e c h a r a c t e r i s t i c s of th e v e s s e l in v e s tig a te d by m e an s of tw o p a r a m e te r s — th e b locked volum e w hich r e p r e s e n ts th a t p a r t of the volum e w hich

Fig. 5

Above. C ount-rate plo tted against tim e at the outle t from a reaction vessel after a mom entary addition of a tracer a t the in le t . The theo re tical average residence tim e is 8= 1 (6= where V is the to ta l volum e of the vessel and v the volum etric flow -rate). The experim ental average residence tim e , 0, is the abscissa for

the centroid of the curve.

Below. The integrated count-rate p lo tted against tim e curve. The abscissa 5 makes the two areas marked "A" equal. T he sectioned area to the-right is a m easure o f the blocked volum e and the area "A” a measure

o f the hold-back.

is not e ff ic ie n tly r e p le n is h e d by th e flow ing liq u id , and th e h o ld -b a c k w hich d e s c r ib e s th e d e g re e of m ix in g in th e e ffe c tiv e v o lu m e [10]. In v e s tig a tio n s by th is tech n iq u e have been p e r fo rm e d on v a r io u s k inds of b a s in s and o th e r p r o c e s s u n i ts , m a in ly in th e c e l lu lo s e in d u s t ry , fo r e x a m p le b le a c h in g to w e r s , p u lp r e s e r v o i r s , p u lp p r e s s e s , d ig e s t e r s an d s e r i e s - c o n n e c te d m ix e r s . U s u a l ly so d iu m b ic a rb o n a te o r a m m o n iu m b ro m id e i s u s e d a s a t r a c e r fo r th e w a te r p h ase ; a lso i r r a d ia t io n in a m ed iu m n e u tro n flux g iv es


s u f f ic ie n t s p e c if ic a c t iv i t ie s o f N a 24 and B r 82. In so m e of th e s e i t w as of in t e r e s t to d e te r m in e th e flow o f th e f ib re p h a s e in th e p u lp , w h ich m a d e la b e ll in g o r ta g g in g of th e f ib r e s n e c e s s a r y . I t h a s b e e n show n th a t th e s im p le s t w ay to ac h ie v e th is i s to u s e 'a g la s s f ib re a s a t r a c e r fo r th e c e l lu lo s e f ib re ; n e u tro n i r r a d ia t io n g iv e s a c o n s id e ra b le N a24 a c tiv i ty in th e g la s s f ib re . O nly in c a s e s w h e re th e f ib re flow in v e ry d ilu ted su sp e n s io n s i s to be s tu d ie d (c o n c e n tra t io n s < 0 .5 % ), th e b e h a v io u r o f th e g la s s f ib r e s h a s b e e n show n to d if fe r f ro m th a t o f th e c e l lu lo s e f ib r e s [1 1 ].

T h e flow p a t te r n in g la s s fu rn a c e s h as b ee n in v e s tig a te d u s in g N a24 a s sod ium c a rb o n a te [1 2 ] o r g la s s of s p e c ia l q ua lity con tain ing co b a lt o r s e le n ium .

2 .3 . M app ing of flow p a t t e r n s in r e c e i v e r s fo r se w a g e o r w a s te w a te r

M om entary o r continuous addition of a rad io a c tiv e t r a c e r so lu tion m akes i t p o s s ib le to m a p th e flow and a c c u r a te ly d e te r m in e th e d ilu tio n of w a s te w a te r in e x is tin g o r p lanned o u tle ts . In th is way w aste w a te r f ro m c e llu lo se f a c to r ie s h as b een follow ed w ith rad io a c tiv e am m onium b ro m id e as a t r a c e r . A c tiv it ie s of th e o r d e r of 1 с m a k e i t p o s s ib le to s tu d y , u n d e r fa v o u ra b le c o n d itio n s , th e flow of w a te r in r e c e iv e r s w ith v o lu m es a round 108 m 3 [13]. T h e c o n c e n tra t io n s of th e w a s te , w h ich w ould r e s u l t a t a s te a d y s ta te w ith a continuous d isc h a rg e , can be d e te rm in e d at v a r io u s po in ts around an ou tle t e i th e r by in te g ra t in g th e m e a s u r in g d a ta f ro m a m o m e n ta ry a c tiv i ty o u tle t [14] o r by m e a n s of con tinuous ad d itio n of a t r a c e r so lu tio n d u rin g a p e r io d çf t im e su ffic ie n t to re a c h the s te ad y s ta te in the zone u n d e r study . T h is l a t t e r m e th o d h a s b ee n u s e d to d e te r m in e th e d ilu tio n fo r th e w a s te s f ro m a la rg e su lp h a te m ill . T he w aste w a te r is c o llec te d in a la rg e p ipe w h ich tak es i t to a p o in t about 5 km f ro m th e c o a s tl in e . T h e l a s t 1000 m of th e p ip e a r e p e r f o r a te d w ith o p en in g s s u i ta b ly s p a c e d . T w o and f o u r - te n th s c u r i e s o f N tU B r 82 w e re in je c te d in to th e w aste w a te r du rin g ap p ro x im ate ly two h o u rs , w hich m ade i t p o s s ib le to d e te rm in e a c c u ra te ly d ilu tio n s as high as 10 4 : 1 in th e r e c e iv e r . A s im i la r in v e s tig a tio n h a s b ee n p e r fo rm e d a t a r e a c to r s i te to d e te r m in e th e s t e a d y - s ta te c o n c e n tra tio n of a c tiv i ty , a t a p la n n e d o u tle t fo r lo w -a c tiv e w a s te . A p p ro x im a te ly l c of ra d io a c tiv e am m onium b ro m id e w as in je c te d d u r in g 8.5 h and th e r e s u l t s of th e in v e s t ig a t io n sh o w ed th a t th e d ilu tio n s w e re a s e x p e c te d .

2 .4 . D e te r m in a t io n o f f lo w -ra te f o r l iq u id s in p ip e s and o p e n s y s t e m s

W a te r - s o lu b le r a d io a c tiv e s a l t s co n ta in in g s h o r t - l iv e d n u c lid e s a r e in w id e sp re a d u se fo r d e te rm in a tio n of the f lo w -ra te s of w a te r and o th e r liq u id s . T h e m o s t co m m o n t r a c e r s a r e so d iu m b ic a rb o n a te (N a24) and am m o n iu m b ro m id e '(B r82). T h e cho ice betw een th e se is u su a lly d ic ta ted by the d is tan ce f ro m a r e a c to r and th e d u ra tio n of th e in v e s tig a tio n . F o u r m ethods a re u sed to d e te r m in e f lo w -ra te s : p a s s a g e t im e o r is o to p e v e lo c ity ; d ilu tio n ; to ta l co u n t; an d to ta l o r c o n tin u o u s s a m p lin g .

In th e f i r s t m e th o d th e t im e i s d e te r m in e d fo r p a s s a g e o f th e t r a c e r b e tw e e n tw o f ix e d d e t e c to r s a t a know n d is ta n c e f ro m e a c h o th e r . In th e d ilu tio n m ethod th e in v e s tig a te d w a te r flow is allow ed to d ilu te a known added am oun t o f c o n c e n tra te d r a d io a c tiv e so lu tio n . T h e flow -rate is th e n d e te rm in e d


f ro m th e d ilu t io n of th e t r a c e r . T h e to ta l c o u n t m e th o d i s b a s e d up o n th e fa c t th a t th e n u m b e r of coun ts r e g is t e r e d by a s c a le r when th e t r a c e r p a s s e s a d e te c to r is in v e rs e ly p ro p o rtio n a l to the flo w -ra te of the liqu id [15]. F inally , th e to ta l s a m p lin g m e th o d i s a v a r ia t io n o f th e to ta l co u n t m e th o d ; in s te a d of m e a s u r in g d i r e c t ly on th e flow , a s a m p le i s ta k e n c o v e r in g th e w ho le p e r io d of t im e n e c e s s a r y fo r th e t r a c e r to p a s s th e sa m p lin g p o in t. A f te r w a rd s th e a v e r a g e a c t iv i ty , i . e . th e a v e r a g e t r a c e r c o n c e n t r a t io n in th e s a m p le , i s d e te r m in e d [16] . -

T h e p a s s a g e tim e m ethod i s in w id e sp re a d u se fo r d e te rm in in g the flow- r a te o f liq u id s in in d u s t r ia l p ip e s [17] . A cond ition is th a t th e c r o s s - s e c t io n o f th e s t r e a m , o r th e vo lu m e of liq u id b e tw een th e d e te c to r s , is a c c u ra te ly know n and fo r th is r e a s o n i t i s b e s t s u ite d fo r m e a s u r e m e n ts o f liq u id s in c lo se d p ip e s w h ich a r e c o m p le te ly f il le d by th e liq u id . M e a s u re m e n ts have b e e n m a d e to d e te rm in e (a) th e to ta l f lo w -ra te of w a s te w a te r f ro m p la n ts , w h e re th e w a te r i s c o l le c te d in a p ip e ; (b) th e to ta l w a te r c o n s u m p tio n in a c e l lu lo s e p la n t by m e a s u r e m e n ts a t th e w a te r in le t ; (c) th e f lo w -ra te in v a r io u s s e c tio n s of co o lin g s y s te m s in e n g in es on la r g e v e s s e l s , and (d) th e f lo w -ra te fo r th e w a te r in r i s e r s and d o w n -c o m e rs on s te a m b o i le r s [18] . T h e a c c u r a c y o f th e m e th o d i s b e t t e r th a n 1% if th e d is ta n c e b e tw e e n th e d e te c to r s i s s u f f ic ie n tly la r g e , but s a t is f a c to r y m e a s u r e m e n ts ca n u su a lly be m ad e ev e n w hen on ly r e la t iv e ly s h o r t s e c tio n s (1 -2 m ) of p ip e a r e a v a ila b le , p ro v id e d th a t th e r e c o rd in g eq u ip m en t i s f a s t enough . T h e c e n tro id s fo r th e tw o a c t iv i ty - t im e c u r v e s a r e u se d fo r th is d e te rm in a tio n .

T h e d ilu tio n m e th o d is u se d m a in ly in open s t r e a m s , w h e re th e c r o s s - s e c tio n of th e flow can n o t be e a s i ly d e te rm in e d [19]. W ith th is m ethod flow - r a t e s o f w a s te w a te r up to 4 m 3 / s h av e b ee n d e te rm in e d f ro m c e l lu lo s e p la n ts an d f lo w -ra te s up to 1 0 0 m 3 / s f o r w a te r in a h y d r o e le c t r ic p o w e r p la n t [2 0 ] .

T h e to ta l sa m p lin g m e th o d is an in te r e s t in g a l te rn a t iv e to th e d ilu tio n m ethod , w hile i t is m o re econom ic as fa r a s the t r a c e r ac tiv ity is concerned . It i s , how ever, n e c e s s a ry to have a c c e ss to a good sam pling pum p fo r sam p ling th e m e a su r in g sa m p le . T he co n s tan cy in the flow -ra te of the pum p should have a t l e a s t th e s a m e a c c u ra c y a s th e r e q u ir e d p r e c is io n in th e f lo w -ra te . I t can be show n th a t f lu c tu a tio n s in th e c a p a c ity of th e pum p, w hich a r e fa s t co m p a re d w ith th e d u ra tio n of th e p a s s a g e o f th e ac tiv ity , p la y an u n im p o rta n t r o l e . A n a l te r n a t iv e p r o c e d u r e , w h e re th e a c c u r a c y i s n o t in f lu e n c e d by pum p quality , m a k es u se of sam p lin g a t r e g u la r in te rv a ls du ring th e p a ssa g e of th e t r a c e r . E q u a l v o lu m e s, of s a m p le s ta k e n r e g u la r ly d u r in g th e w hole a c t iv i ty - t im e c u r v e a r e th e n m ix e d and th e r e s u l t in g m e a n c o n c e n tra t io n is u se d to d e te rm in e th e f lo w -ra te a s fo r the sa m p le ta k en con tinuously [2 1 ] . I t h a s a ls o b e e n show n to be p o s s ib le to u s e th e to ta l s a m p lin g m e th o d fo r d é te rm in a t io n of th e f lo w -ra te in p ip e s . S am p lin g c a n th e n e a s i ly be m ad e by m e a n s of a ta p on th e p ip e , w hich is open d u rin g th e p e r io d ta k e n fo r the t r a c e r to p a s s th e ta p . T h e o u tflo w in g liq u id i s c o l le c te d an d c o n s t i tu te s th e m e a s u r in g s a m p le . C o m p a riso n h a s show n th a t co n s tan c y in th e sa m p le flow ach ieved in th is way is s a t is fa c to ry . U nder a ll conditions the to ta l count and th e to ta l s a m p lin g m e th o d s im p ly th a t in je c t io n of th e t r a c e r so lu tio n in to th e s t r e a m is m ade so th a t no p a r t of the t r a c e r is so h ighly d ilu ted th a t i t w ill no t be o b se rv e d .


2.5. L eak d e tec tio n and lo c a liz a tio n

S h o rt- liv e d r a d io a c tiv e t r a c e r s a r e u se d to a g r e a t ex ten t fo r lo c a tin g le a k s in w a te r p ip e s . T h e t r a c e r so lu tio n is in tro d u c ed in to th e leak in g s e c tio n w hich is c lo se d and pu t u n d e r p r e s s u r e fo r a c e r ta in t im e . A fte rw a rd s th e p ip e is em p tie d and f lu sh ed , and th e a c tiv ity re m a in in g o u ts id e th e p ipe is lo c a te d , and in d ic a te s th e le a k . T h e t r a c e r s g e n e ra lly u se d fo r th is p u r p o s e , a s a ls o in th e c a s e s r e f e r r e d to above , a r e am m o n iu m b ro m id e and so d iu m b ic a rb o n a te . W h e re th e in v e s tig a tio n i s p e r f o rm e d in th e v ic in ity o f a r e a c t o r i t h a s a l s o b e e n p o s s ib le to u s e C l38 ( h a lf - l i f e 37 m in ) .

S o m e tim e s i t c a n b e t im e co n su m in g and in v o lv e g r e a t d if f ic u lty and c o s ts to m ake an in c is io n in a w a te r p ip e , e s p e c ia l ly if th e p ipe i s of la rg e d im e n s io n s and i s b u r ie d in th e g ro u n d , o r i s in a c c e s s ib le fo r d i r e c t in s p e c tio n . P ip e s of th is k ind a r e , h o w e v e r, in m o s t c a s e s a c c e s s ib le at c e r t a in p o in ts , e . g . w h e re a i r in g and d ra in a g e i s m a d e . A n in je c t io n a t th e s e p o in ts can , in generad , be a r ra n g e d w ithout d ifficu lty . A fter a rran g in g in sp e c tio n h o les a t su ita b le d is ta n c e s fro m the po in t of in je c tio n , w hich m ay be n e c e s s a r y in o r d e r to b r in g th e d e te c to r s u f f ic ie n tly c lo s e to th e p ip e , th e d ir e c tio n of th e flow can be e s ta b l is h e d . T h is t r a n s p o r t w ill ta k e p la c e to w a r d s th e le a k if th e p ip e i s c lo s e d and p u t u n d e r p r e s s u r e . T o o b ta in u se fu l r e s u l t s i t is n e c e s s a ry th a t the flow is la rg e enough to c re a te a defined w a te r m ovem ent and to exceed the d isp e rs io n r a te of the t r a c e r .

R a d io a c tiv e t r a c e r s h av e a ls o b ee n u s e d to d e te r m in e le a k a g e f ro m c a n a ls and seep ag e of w a te r u n d er dam s tr u c tu re s . In one c a se the e ffec tiv en e s s of a b a r r i e r of c o n tin u o u s ly -in je c ted s a tu ra te d ca lc iu m hydrox ide so lu t io n u n d e r a d am c o n s tru c tio n w as te s te d . T h e p u rp o s e of th e b a r r i e r w as to p re v e n t leak ag e w a te r con tain ing ca rb o n dioxide fro m attack ing ro ck zones c o n ta in in g so lu b le c a lc i te s t r a t a . A t r a c e r so lu t io n of N a 24 w a s in je c te d in b o re -h o le s in th e ro c k u p s tr e a m of th e b a r r i e r w ith and w ithout th e b a r r i e r in o p e r a t io n . I t w as sh o w n th a t r a p id and d i r e c t t r a n s p o r t f ro m th e in je c tio n h o le s to d o w n s tre a m o b se rv a tio n h o le s o c c u r re d as long as no in je c tio n of c a lc iu m hyd ro x id e w as m ad e , but th a t th is t r a n s p o r t c e a se d when c a lc iu m hyd ro x id e w as in je c te d .

L eakage f ro m a ca n a l lead in g w a te r fro m a lak e to a sm a ll h y d ro e le c tr ic pow er p la n t w as show n by m e an s of rad io a c tiv e am m onium b rom ide; f u r th e r m o re , th e s iz e of th e le a k w as d e te rm in e d . In th is c a s e th e f lo w -ra te of the w a te r in d if f e r e n t s e c t io n s in th e c a n a l w as d e te rm in e d ; d e c r e a s e in th e f lo w -ra te m a d e i t p o s s ib le to c a lc u la te th e le a k a g e f ro m a g iv e n s e c t io n .

W a te r m ovem en t in ro c k at a r e a c to r s i te w as in v e s tig a ted to d e te rm in e th e e f f ic ie n c y of th e d ra in a g e s y s te m . R a d io a c tiv e so lu tio n , co n ta in in g N H jB r62, w as added in d if fe re n t w e lls in th e ro c k in a s e r i e s of in v e s tig a tio n s and th e a c tiv i ty in th e d ra in a g e s y s te m w as d e te rm in e d . It w as p o s s ib le to d e te rm in e th e ex ten t of the d ra in a g e zone fo r the sy s te m and a lso th e p o ro s ity of th e r o c k in th e v ic in i ty of th e in je c t io n h o le s . T h is in fo rm a tio n w as b a se d on d e c r e a s e in th e a c tiv ity a c co rd in g to th e m ethod g iven by MOSER, NEUM AIER and RAUERT [22].

L ea k ag e in a s te a m c o n d e n se r f ro m th e co o lin g w a te r s id e to th e co n d e n s a te h as a lso b ee n s tu d ie d by m e a n s of ra d io a c tiv e am m onium b ro m id e . It w as of in te r e s t to d e te rm in e if a v a ila b le c o n d e n s e rs w e re su ite d fo r u se in n u c le a r p o w e r p la n ts w ith h e a v y -w a te r b o i le r s , w h e re th e h ea v y w a te r


w ould d r iv e th e s te a m tu r b in e s d i r e c t ly . It i s e s s e n t i a l th a t le a k a g e o f th e coo ling w a te r in to th e h e a v y -w a te r c i rc u i t is v e ry sm a ll. T he d e s ire d m e a s u r in g s e n s it iv i ty cou ld no t be re a c h e d in th is c a s e by d i r e c t m e a su r in g even in v e r y l a r g e v o lu m e s o f c o n d e n s a te . F o r th i s r e a s o n e n r ic h m e n t o f th e am m o n iu m b ro m id e in th e s a m p le w as m a d e by an io n e x c h a n g e r . I t w as p o s s ib le to d e te rm in e a le a k of th e o r d e r of 0 .1 1 / d f ro m a p r im a r y c i r c u i t co n ta in in g a p p ro x im a te ly 5000 m 3 w a te r to a se c o n d a ry c i r c u i t (co n d en sa te w ell) co n ta in in g a p p ro x im a te ly 5 m 3 w a te r .

3. MIXING STUDIES

M any p r o c e s s e s in ch e m ic a l and r e la te d in d u s tr ie s aim at m ixing v a rio u s co m p o n e n ts to a h o m o g e n eo u s p ro d u c t. T h is c a n b e a l iq u id , a p o w d e r o r a p a s te . T o s tu d y th e op tim um con d itio n s of su c h m ix e r s , s h o r t- l iv e d r a d io a c tiv e t r a c e r s have ex ten s iv e ap p lica tio n , e .g . in th e m ix ing of c a rb o n p a s te fo r S ô d e rb e rg e l e c t r o d e s , of r u b b e r and g r e a s e , o f p e t r o le u m f r a c t io n s and c a t t le fee d . In sm other p a p e r in th e s e P ro c e e d in g s th e in v e s tig a tio n of p o w d er m ix in g i s d is c u s s e d in d e ta i l [23].

4 . TAGGING O F S T E E L BATHS FO R ID EN TIFIC A TIO N PU R PO SES

T a g g in g w ith ra d io a c t iv e n u c l id e s c a n b e u se d to r e l a t e m a n u fa c tu re d s te e l p ro d u c ts to c e r ta in in d iv id u a l s te e l b a th s . If th e p ro d u c t i s to b e fo llow ed th ro u g h m any m an u fac tu rin g s te p s , th e u se of lo n g -liv e d iso to p es m u st be c o n s id e re d . Such ta g g in g w ith v a r io u s lo n g - liv e d n u c lid e s h a s b e e n su g g e s te d and u se d fo r th e id e n tif ic a tio n of tw o q u a lit ie s of s te e l u se d fo r h e a t- e x c h a n g e r tu b e s in th e S w ed ish n u c le a r r e a c to r R 3 [24]. In th e s a m e w ay i t i s p o s s ib le to ta g th r e e o r m o re q u a l it ie s bu t th is w ill r e s u l t in a r a th e r c o m p lic a te d m e a s u r in g s y s te m to d is t in g u ish , on a ro u tin e b a s is , b e tw een th e d if fe re n t tag g ed m e lts , a lthough in so m e c a s e s up to fo u r d if fe re n t tagg ing n u c lid e s can be d e te rm in e d in th e s a m e m e a su r in g o p e ra tio n .

S h o rt- liv e d n u c lid es a re a lso u se d in th e s te e l in d u s try . R e se a rc h m e lts a r e o ften m a n u fa c tu re d w h ich m a y h av e u n ex p e c ted p r o p e r t ie s . T h e r e f o r e s p e c ia l p re c a u tio n s sh o u ld be ta k e n to avo id su c h goods being d e l iv e re d to a c u s to m e r . It c a n u s u a l ly b e e s ta b l is h e d in a s h o r t t im e w h e th e r s u c h a m e lt m u s t b e ta k e n ou t o f th e p ro d u c tio n l in e . A s h o r t - l iv e d ta g g in g s u b s ta n c e i s a p p lic a b le h e r e .

If a p h y s ic a l t r a c e r is u s e d i t s p e rc e n ta g e m u s t b e so low th a t i t i s m e ta l lu rg ic a l ly in s ig n if ic a n t and th e t r a c e r e le m e n t shou ld p r e f e r a b ly have a h igh o x id a tio n p o te n tia l so th a t th e p o s s ib le lo s s due to o x id a tio n in to th e s la g p h a s e d u r in g ta p p in g and m o u ld in g i s m in im iz e d . D epend ing upon th e in e r tn e s s of th e tag g in g su b s ta n c e , th e add ition ca n b e m ade in th e fu rn a c e o r in th e la d le . T h e m o v e m e n t in th e la d le i s g e n e ra l ly in te n s e en o u g h to r e s u l t in c o m p le te m ix in g of th e s u b s ta n c e o v e r th e m o lte n m e ta l p h a s e .

T h e s o u rc e is o ften i r r a d ia te d a s a th in m e ta l l ic c y l in d e r o r s h e e t o r , in th e c a s e o f m o r e r e a c t iv e m e ta l , in a c lo s e d a lu m in iu m c a n , an d th i s s m a ll s o u rc e i s m oun ted in a ho llow c y lin d e r of i r o n o r a lum in ium m ounted on a long ro d . T he s h o r t- l iv e d t r a c e r s u se d fo r su c h tag g in g a r e M o " , W i87


and Au!98 fo r s te e l , and CuS4 and Aui98 fo r c o p p e r -b a s e d a llo y s . U n d e r v a r io u s c o n d itio n s th e d is tr ib u t io n c o e ffic ie n t fo r tu n g s te n and m olybdenum b e tw e en th e s te e l and th e s la g p h a se h as b een e s ta b l is h e d as se c o n d a ry r e s u l ts of th e s e in v e s tig a tio n s .

5. "W EIGHING"

If a know n am o u n t of a fo re ig n m a te r i a l is ad d ed and h o m o g e n e o u s ly d is tr ib u te d in a p h a se , the to ta l vo lum e o r w eight of th is p h ase can be ca lc u la te d a f te r th e c o n c e n tra t io n of th e fo re ig n m a te r i a l h a s b e e n d e te rm in e d in a sa m p le . T h is can , of c o u rse , be done by ch em ica l m ean s, but the t r a c e r te c h n iq u e o f fe rs a s im p le r and f a s te r m e th o d . T h e am o u n t o f s la g in open h e a r th fu rn a c e s h as th u s been d e te rm in e d by adding a known am ount of L a 140

a s ox ide ; s a m p le s ta k e n a t d if fe r e n t t im e s sh o w ed w hen th e t r a c e r w as h o m o g e n e o u s ly d is t r ib u te d o v e r th e s la g p h a s e and th e n th e a c t iv i ty d a ta enab led th e w eigh t of th e s la g to be ca lc u la te d [25]. It has a lso been p o ss ib le to d e te r m in e th e am o u n t o f s la g r e m a in in g in th e fu rn a c e a f te r p o u rin g . T h e s e m e a s u r e m e n ts c a n b e m a d e w ith o u t in te r f e r in g w ith o p e ra tio n , a s i s a ls o show n by th e d e te rm in a tio n of th e am o u n t o f m e rc u r y in c h lo r in e - a lk a li c e l ls in th e e l e c t ro - c h e m ic a l in d u s t ry [26]. H e re i t h a s b ee n show n th a t a c h e m ic a l t r a c e r is n e c e s s a ry . T hus Hg2° 3 is added in a known am ount and th e sp e c if ic a c tiv ity of th e m e rc u ry in th e c e lls d e te rm in e d a f te r hom og eneous d is t r ib u t io n has been re a c h e d .

T h e s h o r t- l iv e d n ic k e l iso to p e Щ65 is a lso u se d fo r a c c u ra te d e te rm in a tio n of th e am o u n t o f m o lte n m e ta l in f u rn a c e s w h e re e x p e n s iv e h ig h - a llo y s te e l i s p ro d u c e d [27]. T h is know ledge is of g r e a t im p o r ta n c e fo r the a d d itio n of a c c u r a te am o u n ts of th e a llo y in g co m p o n en ts . A s m a ll q u an tity o f N i65 w as show n to r e m a in q u a n tita tiv e ly in th e s te e l p h a s e . A fte r hom og e n iz a tio n , th e d ilu tio n of th e added m a te r ia l is d e te rm in e d and f ro m th is th e q u an tity of m o lte n m e ta l i s c a lc u la te d . T h is ap p lic a tio n cou ld r e s u l t in . a sa v in g w hich w ould c o v e r c o s t of th e in s ta l la t io n in a la r g e s te e l p la n t of a r e s e a r c h r e a c to r fo r th is p u rp o se only .

6 . ID E N T IF IC A T IO N O F N O N -M E T A L L IC IN C LUSION S AND SU R FA C E D E F E C T S

In th e s t e e l in d u s t ry th e o c c u r re n c e of s m a ll s i l i c a te a g g re g a te s ju s t b e lo w th e s u r fa c e , o r d is t r ib u te d a l l o v e r an in g o t, i s c a u s in g r e je c t io n s , and th u s ec o n o m ic lo s s e s . One of th e m o s t v a lu a b le u s e s of ra d io a c tiv e t r a c e r s in th is in d u s t ry is th e i r a p p lica tio n to s tu d ie s of th e o r ig in and fo rm a tio n m e c h a n is m s of ' 'in c lu s io n s " . F re q u e n t ly -o c c u r r in g e le m e n ts in th e s e in c lu s io n s a r e a lu m in iu m , c a lc iu m , s il ic o n , m a n g a n e se and oxygen. O f th e s e , c a lc iu m h a s tw o r a d io a c tiv e is o to p e s , bo th hav ing c e r ta in d ra w b a c k s ; th e so ft b e ta - r a d ia t io n , th e ra d io to x ic ity of th e lo n g - liv e d C a45 and th e h ig h c o s t o f C a4V. M a n g a n e se h a s th e s h o r t - l iv e d r a d io a c t iv e is o to p e M n66 and tw o lo n g -liv e d a c c e le ra to r -p ro d u c e d iso to p e s M n52 and M n54. The o th e rs have no ra d io iso to p e s w ith su ffic ie n tly long h a lf - liv e s . It is th e re fo re


n e c e s s a ry to u se p h y s ic a l la b e llin g of the m a te r ia ls su sp e c te d of con tribu ting to th e in c lu s io n s .

T h e m o s t su ita b le r a d io is o to p e s fo r su c h p u rp o s e s belong to th e g roup of r a r e e a r th s . D epending upon the tim e w hich e la p se s d u ring the m ach in ing t r e a tm e n t , b e fo re the in c lu s io n s o r su r fa c e d e fe c ts can be exam ined , s e v e ra l n u c lid e s , w ith a lm o s t id e n tic a l m e ta l lu rg ic a l b eh av io u r, can be chosen . W hen th e d u ra tio n of th e p ro d u c tio n s te p s i s w eek s o r m o n th s , a s fo r th e p r o d u c t io n of tu b e s , p ip e s and r o l le d s t e e l , lo n g - l iv e d n u c l id e s s u c h a s Sc4e, C e141, T b ltíuo r L u 177 m u s t be u se d , but in m an y c a s e s , e s p e c ia lly fo r m ild s te e l , L a 140 can be u se d fo r th e la b e ll in g of su sp e c te d s o u rc e s .

T h e la b e ll in g of ox ide m a te r ia l c a n b e p e r fo rm e d by m ix in g th e c o m pounds w ith fin e ly d ivided ir ra d ia te d lan thanum oxide. H ow ever it has p roved to be b e t te r to im p re g n a te r e f r a c to r i e s , fo r exam ple , w ith a so lu tio n of L a 140

n i t r a t e . W hen h e a te d th e n i t r a t e d e c o m p o s e s in to th e o x id e . I t h a s b e e n checked th a t th is la b e llin g agent is not d is so lv ed by w a te r and th a t the t r a c e r i s fix ed on th e s u r f a c e of th e s i l i c a te g r a in s . L a 140- la b e l le d r e f r a c t o r i e s have re v e a le d th e ex ten t to w hich exogenous so u rc e s co n trib u te to in c lu s io n s and s u r fa c e d e fe c ts , and a lso co n trib u tio n s f ro m th e s o -c a lle d " in g o t-fo a m ". T h is is a s i l ic a te p h a se , o r ig in a tin g f ro m s e v e r a l s o u rc e s , w hich is fo rm e d on the s u r fa c e of th e ingot d u rin g m oulding and can be m ech a n ica lly enc lo sed n e a r th e s u r fa c e in th e fo rm of c o h e re n t d is c s o r n u m e ro u s s m a ll s p h e re s . A s e r ie s of in v e s tig a tio n s co m p ris in g changes of tapp ing te m p e ra tu re , m ouldin g sp e e d and k ee p in g t im e of th e la d le , in d ic a te d th e m a n n e r in w h ich th e n u m b e r of in c lu s io n s in m ild s te e l p ro d u c ts can be d e c r e a s e d . S im ila r in v e s t ig a t io n s w ith L a 140- la b e l le d r e f r a c t o r i e s h av e r e c e n t ly b e e n r e p o r te d f ro m G e rm a n y [28].

7. ORGANIZATIONS IN T H E INDUSTRIAL ISO T O PE TEC H N IQ U ES F IE L D

In so m e c o u n tr ie s r e s e a r c h and d e v e lo p m e n t in th e f ie ld of in d u s t r ia l iso to p e te c h n iq u e s is p e r fo rm e d by a d iv is io n of th e n u c le a r e n e rg y o rg a n iza tio n . In o th e r c o u n tr ie s s e p a ra te o rg an iz a tio n s ex is t w ith th is aim com bined w ith a c o n su lta tio n s e rv ic e . In Sw eden, th e Iso to p e T e c h n iq u e s L a b o ra to ry (ITL) w as begun in 1960 a s a re o rg a n iz a t io n of a r e s e a r c h group a t the R oyal In s titu te of T echnology . T he m e m b e rs ot IT L , at p re s e n t som e th ir ty p riv a te co m p an ie s and g o v e rn m e n ta l o rg a n iz a tio n s , p ay an annual fee w hich enab les IT L to m a in ta in a r e s e a r c h and d e v e lo p m e n t p r o g ra m m e , s u p p o r te d a l s o by th e T e c h n ic a l R e s e a r c h C ounc il. C o u rs e s have b een g iven to t r a in en g in e e r s in u s e s o f r a d io is o to p e s , a s h o r t c o u r s e on u s e s of s e a le d s o u r c e s and a m o re co m p le te c o u rs e c o v e rin g v a r io u s u s e s of t r a c e r s and an a ly tica l m e th o d s . T he IT L a lso p e r fo rm s co m p le te t r a c e r in v e s tig a tio n s in in d u s try a s r e q u e s te d by i t s m e m b e r s o r o th e rs and su p p lie s i t s m e m b e rs w ith in fo rm a tio n and ad v ice on r e c e n t d ev e lo p m e n ts judged to be of in te r e s t in th e v a r io u s b r a n c h e s of in d u s t ry . F o r th is p u rp o s e IT L i s p u b lis h in g a s h o r t q u a r te r ly r e v ie w and s u r v e y p a p e r s on in d u s t r i a l is o to p e te c h n iq u e s an d a l s o g iv e s l e c tu r e s on th e r a d ia t io n p r o te c t io n a s p e c ts o f in d u s t r i a l u s e s o f r a d io is o to p e s . A p p ro x im a te ly 65 in d u s t r ia l e x p e r im e n ts a r e co n d u c te d an n u a lly .


R E F E R E N C E S

[1] RUTLE, J . , "Investigation o f M aterial Transport in wet-process Rotary Kilns by Radioisotopes", P it and Quarry 48 1 ( 1955) 120.

[2] HOGREBE, K. und LEHMANN, W. S . , " 'T ra c e r1- Versuche an Drehôfen m it La140 ", Z em ent-K alk-G ips 9 (1956) 210.

[3] ERWALL, L.G. and UUNGGREN, K ., "Recent Uses o f Radioisotopes in technological Research and Control in Sweden", 2nd UN Int. Conf. PUAE 19 (1958) 3.

[4] FINEMAN, O ., "Flisbitars vandring i Kamyrs kontinuerliga kokare", Svensk Papperstidning 60 (1957)425. ~ '

[5] HAMILTON, R .P ., "M easurem ent of Kamyr continuous Kraft digester Cooking C ycle using radioactive Tags". Tappi 44 (1961) 647.

[6] KOHN, A ., «É tude de la déscente des charges au haut-fourneau5̂ Radioisotopes in Scientific Research, Proc. 1st (UNESCO) In t. Conf. (Paris 1957) 1 (London 1958) 302.

[7] ERWALL, L .G ., "Anvândning av radioaktiva isotoper inom gruv- och jàm han teringen", Jernkontorets Ann. 142(1958) 369.

[8] WRAMSTEDT, S ., "D eterm ination o f the re ten tion T im e o f the Sludge Phase and the Liquid Phase inThickeners by means of rad ioactive T racers’*, Socker 14 (1958) 113.

[9] DANCKWERTS, P. V . , <<L'utilisation de traceurs dans les recherches industrielles G énie C him ique83 (1960) 75.

[10] LUOTO, U .A . and ROTKIRCH, E ., "T racer Techniques in the Finnish Industry", 2nd UN In t. C onf. PUAE 19 (1958) 28.

[11] FINEMAN, O ., "Spârforsôk m ed radioaktiva isotoper inom cellulosafabriker", Svensk Kemisk Tidskrift 71 (1959) 452.

[12] FISCHER, R ., "Strômungsuntersuchungen an einer technischen Glaswanne m it Na24” , Silikattechnik 11£1960) 559. ~

[13] LJUNGGREN, K. e t a l . , ’’T racing o f W ater Flow by m eans o f rad io ac tiv e Isotopes and S c in tilla tion C ounters”, Intern. J. Appl. Radiation and Isotopes 5 (1959) 204.

[14] BERG, O . and SOMER, E ., "D eterm ination of the Distribution of sewage Concentration in large naturak Waters from planned Sewage O utle ts", Production and Use of short-lived Radioisotopes from Reactors, These proceedings.

[15] HULL, D. E ., "T he to ta l count T echn ique: A new Principle in Flow M easurem ent", In te rn . J . Appl. .Radiation and Isotopes 4 (1958) 1.

[16] HULL, D .E . , e t a l . "Isotope Engineering a t large flow Rates", Trans. Am . N ucl. Soc. 3 (1960) 453,[17] CLAYTON, C .G . , CLARK, W .E . and BALL, A .M ., "T he accu ra te M easurem ent o f tu rbu len t Flow

in Pipes using the isotope velocity M ethod and the Effect o f som e Restrictions on optim um O peration", P roc. Symp. on flow M easurem ent in closed Conduits, Glasgow (1960) London.

[18] CARLSON, R ., CEDERBERG, B. and UUNGGREN, K ., "M easurem ents o f th e w ater C ircu la tio n in a high-pressure n a tu ra l-c ircu la tio n B oiler", Com bustion 33 12 (1962) 25.

[19] CLAYTON, C .G . , e t a l . , '/The a ccu ra te M easurem ent o f tu rbu len t Flow in Pipes using ra d io ac tiv e Isotopes - The isotope dilution M ethod”, Proc. Symp, on Flow Measurement in closed Conduits, Glasgow(1960) London.

[20] FINEMAN, O ., "Bestam ning av vàtskeflôden pá m ellan 5 och 200 ms /sek m ed h jà lp av rad ioak tiva iso toper", Svensk K em isk T idskrift 71 (1959) 452 .

[21] CLAYTON, C .G . , Personal com m u n icatio n ,[22] MOSER, H ., NEUMAIER, F. und RAUERT, W ., "Die Anwendung radioaktiver Isotopen in der Hydrologie.

П . Ein V eïfahren zur Erm ittlung der E rgiebigkeit von G rundwasserstrôm ungen", A tom kem energ ie 2 (1957) 225.

[23] BJERLE, I . and FORSBERG, H .G ., Studies o f Pow<ler M ixing w ith sh o rt-liv ed Radioisotopes,[24] AMEEN, L, and FORSBERG, H .G ., "M ârkning av s tá l m ed radioaktiva iso toper", Teknisk T idskrift 91

(1961) 671.[25] WIDMARK, H ., "Infodringens ro ll vid chargefôrloppet i den sura M artinprocessen", Jernkontorets Ann.

144 (1960) 1.[26] CAMPBELL, J .G ., "Mercury M easurement by Dilution*of a radioactive Isotope", Appita 12 (Sept. 1958)-

51.


[27] SCHMITT, R.A. and SHARP, R .A ., "Use o f short-U ved Radioisotope 2 .56-h N i“ in de term in ing the m e lt C onten t in o p en -hearth Furnaces")G eneral A tom ic Report G A -1083, San Diego (1 9 6 0 ) .

[28] PRÔPSTL, G .H ., "Radioaktive M arkierungstechnik zur Untersuchung von m etallurgischen Vorgângen im Stahlwerk". Stahl und Eisen 80 (1960) 863,

D I S C U S S I O N *

R . COURTOIS: In y o u r o r a l p r e s e n ta t io n you m e n tio n ed am e x p e r im e n t on flow m e a s u re m e n ts on a b o ile r , and you sa id th a t you w e re ab le to c a r r y ou t c o n tin u o u s m e a s u r e m e n ts . C ou ld you s a y so m e th in g ab o u t th e m e th o d you u s e d in o r d e r to o b ta in co n tin u o u s r e s u l t s ?

L .G . ER W A LL: T h e con tin u o u s m e a s u r e m e n ts w e re c a r r i e d ou t w ith a tu rb o -w h e e l in s ta l le d in one of th e p ip e s ; tw o of th e b la d e s w e re la b e lle d w ith C o60. A c o l l im a te d s c in t i l la t io n d e te c to r c o n n e c te d to a v e r y f a s t r e c o r d e r c o n t in u o u s ly r e g i s t e r e d th e a c t iv i ty o u ts id e th e p ip e , th u s g iv in g th e r a t e o f re v o lu tio n , w h ich in tu r n m ade ' i t p o s s ib le to c a lc u la te th e flow - r a te a f te r c a lib ra tio n te s t s . D e ta ils can be found in the jo u rn a l "C om bustion" 33 12 (1962) 25.

A . KOHN: In s e c tio n s 4 and 5 of y o u r p a p e r you a ls o m e n tio n th e u s e of ra d io iso to p e s fo r tagg ing s te e l b a th s and fo r "w eighing" s la g in in d u s t r ia l f u rn a c e s . A re th e s e m e th o d s b e in g u s e d in in d u s t r y fo r r o u t in e m e a s u r e m e n ts ?

L .G . ERW A LL: B o th m e th o d s a r e su ita b le fo r ro u tin e m e a s u re m e n ts . T h e la b e l l in g of s t e e l fo r id e n tif ic a tio n w a s f i r s t u s e d f o r s p e c ia l - q u a l i ty s te e l s , su c h a s th a t em ployed fo r h e a t-e x c h a n g e r tu b e s in r e a c to r s . D e ta ils h av e b e e n p u b lis h e d in S w ed ish and in G e rm a n (in " S ta h l und E is e n " ) . A s f a r a s th e d e te r m in a t io n of s la g c o n te n t i s c o n c e rn e d , s u c c e s s iv e s e r i e s of "w e ig h in g s" , e a c h c o v e r in g s e v e r a l ty p e s of s la g , h av e show n th a t th is m eth o d ca n be u se d fo r ro u tin e m e a s u re m e n ts , fo r ex am p le in o p e n -h e a r th f u r n a c e s . T h e f i r s t "w e ig h in g s" w e re m a d e u s in g L a i4u a s t r a c e r , b u t a s e r i e s of "w e ig h in g s" w ith T b lriu h a s a l s o b e e n c a r r i e d ou t.

C . T A Y L O R : D o you th in k is o to p e m e th o d s f o r m e a s u r in g flow m a y b e u s e fu l on a r o u t in e b a s i s ? O ne c a n im a g in e s y s te m s in w h ich a s im p le d e te c to r i s b u ilt in to th e p la n t, and a s ta n d a rd c a r t r id g e co n ta in in g a sm a ll am o u n t of a s h o r t - l iv e d iso to p e i s in je c te d w h e n e v e r a m e a s u r e m e n t h a s to b e m a d e .

L .G . E R W A L L : G e n e ra lly sp e a k in g , I th in k th e t r a c e r m e th o d s w ill f in d t h e i r w ay in to r o u t in e u s e , a l th o u g h I c a n w e ll im a g in e th a t s e v e r a l a t l e a s t of th e m e th o d s m ay be b a s e d on th e u s e not of r e a c to r s , bu t of n eu tr o n g e n e ra to r s fo r in s itu a c tiv a tio n of " n a tu ra l" o r added in ac tiv e t r a c e r s .

I would add th a t I th in k th e re is a tendency am ong en g in e e rs to overlook th e u s e fu ln e s s o f is o to p e s fo r c a l ib r a t in g o th e r m e a s u r in g d e v ic e s . M o st of th e iso to p e m ethods a r e ab so lu te m e a su r in g m ethods and they could th e re fo re be u se d advan tag eo u sly to c a l ib ra te , sa y , con tinuous f lo w -ra te m e a s u r ing d e v ic e s .

* See also discussion on the next paper in theseproceedingsby K. Friihauf.


G . KIKNADZE: In co n n ec tio n w ith th e q u es tio n r a i s e d by M r. T a y lo r ,1 w ould l ik e to s a y th a t in th e m in in g in d u s try n e u tro n s o u rc e s can b e u se d to a u to m a tiz e p r o c e s s e s fo r c o n c e n tra tin g m a n g an e se o r e s . T h e f irs t , s te p s in th is d ir e c t io n w e re ta k e n in th e In s titu te of P h y s ic s of th e G eo rg ia n A ca d em y of S c ie n c e , w h e re eq u ip m en t h a s b ee n m a d e fo r d e te rm in in g th e m a n g a n e se co n ten t of th e o r e . T h e eq u ip m en t c o n s is ts o f a n e u tro n s o u rc e and a r e c o r d e r , th e l a t te r being u sed to d e te rm in e th e am ount of rad io a c tiv e M n56 (h a lf- life 2.54 h) in an o re sa m p le p re v io u s ly i r ra d ia te d by th e n eu tro n s o u r c e . T h e eq u ip m en t i s u se d in th e o r e c o n c e n tra tio n p la n ts a t th e m a n g a n e s e d e p o s its in C h ia tu ra , G e o rg ia , USSR.

W .W . M EINKE: Since m en tion h as b een m ade of the p ro d u ctio n of sm a ll a m o u n ts of s h o r t - l iv e d r a d io is o to p e s by n e u tro n g e n e r a to r s , I w ould l ik e to d e s c r ib e th e u s e of an iso to p ic n e u tro n s o u r c e fo r a s im i la r p u rp o s e in th e U n ite d S ta te s . T h e s h o r t - l iv e d d y s p ro s iu m a c t iv i ty ( h a lf - l if e a p p ro x .2 m in ) i s a c tiv a te d by a 5 -g a m e r ic iu m -b e ry l l iu m s o u rc e and in je c te d in to th e w a te r s o f a b a y (fo r th i s u s e e v e n is o to p e s a s s h o r t - l iv e d a s I 131 a r e p ro h ib ite d ). T h is m ethod is being u sed to m e a su re th e c u r re n ts at the bottom o f th e bay , bu t th e p r in c ip le s invo lved h e re a r e of c o u r s e eq u a lly ap p lica b le to in d u s try .

J . WATT: R eg ard in g the u se of n eu tro n g e n e ra to rs in in d u stry , I r a th e r fe e l th a t th e ir ap p lica tio n w ill be v e ry lim ite d in view of th e ex tensive sh ie ld ing th a t is r e q u ir e d . Could M r. E rw a ll com m ent on th is ?

L . G. E R W A L L : In so m e c a s e s th e r e m ig h t w e ll be d ra w b a c k s f ro m th e ra d ia t io n p ro te c t io n p o in t of v iew , but in o th e rs I th in k n e i th e r th e c o s t n o r th e sh ie ld in g would be a s e r io u s d isad v an tag e . H ow ever, i t is en c o u rag in g to h e a r abou t th e r e s e a r c h b e in g c a r r ie d out on r a d io a c tiv e n e u tro n s o u r c e s , w h ich do n o t c r e a te th e s a m e r a d ia t io n p r o te c t io n p r o b le m .

W .W . M EIN K E: I w ould l ik e to c o m m e n t on th i s n e u tro n g e n e r a to r q u es tio n . M ost in d u s t r ia l p la n ts th a t I have se e n have lo ts and lo ts of em pty s p a c e , and i t i s v e ry e a sy to pu t a few fe e t of c o n c re te in th is em p ty sp a ce a s sh ie ld in g .

C . T A Y L O R : I w ou ld l ik e to s a y a w o rd on b e h a lf o f r e a c t o r s h e r e . I t w ou ld b e v e r y e a s y to p ro v id e a r e g u la r su p p ly of " c a r t r id g e s " f ro m a c e n t r a l r e a c t o r . T h is w ould b e b e t te r th a n h a v in g a n e u tro n g e n e r a to r in e a ch fa c to ry . By u sin g a c e n tra l r e a c to r the ra d ia tio n p ro b lem s at the factory w ould be m in im ized .

L .G . E R W A L L : It d ep en d s on th e d is ta n c e s in v o lv ed of c o u r s e . I am s u r e th a t in m a n y c a s e s th e u s e of s h o r t - l iv e d t r a c e r s in in d u s t ry w ill be f a c i l i ta te d by c e n t r a l r e a c to r s , a s we have s ta te d in o u r in tro d u c tio n . F o r e x a m p le , in S tockholm we a r e in th e fav o u rab le p o sitio n of having a r e a c to r in s id e th e c i ty and we h av e u s e d c h lo r in e - 3 8 , a 3 7 -m in is o to p e , f o r le a k lo c a l iz a t io n in th e m u n ic ip a l g a s su p p ly .

R . COURTOIS: I would lik e to a g re e w ith an opinion o r ig in a lly e x p re sse d by M r. H o u rs , n am e ly th a t one should pay m o re a tten tio n to the developm ent o f c o w s , w h ich p ro v id e an e v e r - r e a d y s o u r c e of s h o r t - l iv e d is o to p e s fo r in d u s t r y . T y p ic a l a r e T e -> I132, S r - » Y 9 0 > G a - > G e 6 5 , e tc .

L .G . ERW ALL: T h e cow s a r e no doubt a v a luab le com plem en t to o th e r iso to p e -p ro d u c in g f a c i l i t ie s . We shou ld not n eg lec t any p o ss ib ility .

W. W. M EINKE: One f u r th e r co m m en t. I th in k th a t , s in c e M r. T a y lo r w o u ld l ik e to k ee p r e a c t o r s in th e p ic tu r e , w e o ugh t a ls o to r e a l i z e th a t ,


j u s t a s you c a n sh ip a r a d io a c t iv e cow , so to o you c a n sh ip n e u t ro n s by m e an s of n e u tro n s o u rc e s o r ra d io a c tiv e s o u rc e s th a t have been ac tiv a te d in th e r e a c to r . One ex a m p le is th e a n tim o n y -b e ry lliu m s o u rc e .u s in g Sb124. A lth o u g h th e r e a r e c o n s id e r a b le s h ie ld in g p r o b le m s w ith s o u r c e s o f th i s ty p e , one sh o u ld n o t lo s e s ig h t of th e m a n y p o s s ib le a p p l ic a tio n s of th e s e s im p le , lo w - le v e l s o u r c e s o f n e u tro n s .

STUDIES WITH SHORT-LIVED RADIOISOTOPES IN THE CHEMICAL PROCESS INDUSTRY

K. FRÜHAUFFARBWERKE HOECHST AG, FRANKFURT AM MAIN-HOECHST,

FEDERAL REPUBLIC OF GERMANY


STUDIES WITH SHORT-LIVED RADIOISOTOPES IN THE CHEMICAL PROCESS INDUSTRY. During the past five years Farbwerke Hoechst AG has used short-lived radioisotopes,Na24, M n56, Cu64, Br82, Y90, I 132, ga i3Tm and La14* in evaluating perform ance charac te ris tics o f c h em ica l production plants.

Labelled particles were prepared for the m easurem ent of liquid flow in pipes and reactors, and for the investigation of grain m ovem ent in a rotary kiln. In the sam e m anner pebble movement in a crude oil cracker was studied. For m easuring the distribution and residence tim e of liquids in reactors in jections o f labe lled solutions were m ade in to aqueous, oiganic and o iganom etallic m edia . S im ilar methods were applied for the determ ination of m ixing tim e and contents of storage containers, for leak detection and an exam ination of dyestuff washing in a filte r press.

The activities required were produced mainly by irradiation in FRF (Forschungsreaktor Frankfurt),the 50 kW homogeneous reactor of Frankfurt University.

As an exam ple of the application of an isotope generator in the chem ical process industries, an extraction device for the repeated preparation of several m illicuries of ВаАЗ,ш (2. 6 min) in a high-boiling organicsolvent is described.

ÉTUDES A L'AIDE DE RADIOISOTOPES DE COURTE PÉRIODE DANS L'INDUSTRIE CHIMIQUE. Depuis cinq ans, la société Farbwerke Hoechst AG em ploie les radioisotopes de courte période pour évaluer les caractéristiques de rendem ent des usines chimiques: Z4Na, 56M n,64C u ,8zBr,*°Y.132I, 137mBa,140La.

On a préparé des m olécules m arquées pour m esurer l ’écou lem ent de liquides dans des canalisations e t dans des réacteurs e t pour suivre le m ouvement des graines dans un four rotatif. On a étudié de la m êm e façon le m ouvem ent des boulets dans un dispositif servant au cracking du pétrole brut. En vue de mesurer lad is tri- bution e t le temps de séjour des liquides dans les réacteurs, on a injecté des solutions marquées dans des m ilieux aqueux, organiques e t organom étalliques. Des méthodes analogues ont é té utilisées pour déterm iner le temps de m élange e t la contenance des récipients de stockage, pour dé tecte r les fuites e t exam iner le lessivage des colorants dans un filtre-presse.

La p lupart des m atiè res radioactives requises ont é té obtenues par irrad iation dans l ’in s ta lla tio n FRF (Forschungsreaktor Frankfurt) réacteu r hom ogène de 50 kW de l'U n iversité de Francfort.

Com m e exem ple d ’application d 'un générateur d ’isotopes dans les industries chimiques, l ’auteur décrit un ex tracteur perm ettant la préparation répétée de plusieurs m illicuries de l3 ,m Ba (2 ,6 min) dans un solvant organique en forte ébullition.

ИССЛЕДОВАНИЯ С ПОМОЩЬЮ КОРОТКОЖИВУЩИХ И3.0Т0П0В В ХИМИКО-ТЕХНОЛОГИЧЕСКОЙ ПРОМЫШЛЕННОСТИ. В последние пять лет фарбверке Хоехст А.Г. при оценке рабочих характеристик химических заводов использовало следующие радиоизотопы: Na24, Mn5e> Cu64, Br82, Y90, J 132, Ba137m, La140.

Приготавливались меченые частицы для измерения потока жидкости в трубах и реакторах и для исследования движения зерен во вращающейся печи для обжига. Таким же образом Изучалось движение твердых частиц при обработ ке сырой нефти. Для измерения распределения времени пребывания жидкостей в реакторах в водную, органическую и металлорганическую среду вводились меченые растворы. Подобные методы применялись для определения времени смешения и содержания контейнеров, для хранения в целях обнаружения утечки и исследования красителя в прессфильтре.Требующиеся радиоактивные изотопы получались главным образом с помощью облучения в гомогенном реакторе FRF, мощностью 50 квт, франкфуртского университета.В качестве примера описывается применение изотопного генерат ора в хим ической обрабатывающей промышленности , экстрактора для многократного приготовления нескольких микрокюри Ва137(2,6 мин) в органическом растворителе с высокой температурой кипения.

249

250 K. FROHAUF

ESTUDIOS CON RADIOISÓTOPOS DE PERÍODO CORTO EN LA INDUSTRIA QUÍMICA. En e l curso de los últim os cinco arios, la firma Farbwerke Hoechst AG. ha venido utilizando los siguientes radioisótopos de período corto para evaluar las características de rendim iento de sus instalaciones industriales: 24N a,*M n, MC u ,82Br, * Y , i32i, ísim ga y i«La _

Se prepararon partículas m arcadas a fin de m edir e l flujo de líquidos en tuberías, autoclaves, e t c . , e investigar los m ovim ientos de m asas pulverulentas en un horno rotatorio . De la m ism a m anera , se estudió e l m ovim iento del relleno en una columna de cracking por petróleo crudo. Se inyectaron soluciones marcadas en medios acuosos, orgánicos y organometálicos con objeto de m edir la distribución y e l tiempo de permanencia de líquidos en recipientes de reacción. Aplicando métodos sim ilares, se determ inaron los tiempos de m ezcla y e l con ten ido de depósitos, se de tecta ron fugas y se estudió e l lavado de colorantes en un filtro prensa.

Los radioisótopos necesarios se obtuvieron principalm ente por irradiación en e l reactor homogéneo FRF (Forschungsreaktor Frankfurt) de 50 kW de la Universidad de Frankfurt.

Com o ejem plo de la ap licac ión de un generador de isótopos en la fabricación de productos quím icos, la m em oria describe un dispositivo dé extracción para la preparación repetida de varios m ilicuries de 13' lnBa (2, ê min) en un disolvente orgánico de elevado punto de ebullición.

1. INTRODUCTION

T h e c a p a b i l i t ie s of s m a ll r e s e a r c h r e a c to r s and th e r e q u i r e m e n ts of th e c h e m ic a l p r o c e s s in d u s try w h ere ra d io iso to p e s a r e u se d have one th ing in co m m o n : p r e f e r e n c e fo r s h o r t - l iv e d r a d io is o to p e s . S m a ll r e s e a r c h r e a c to r s a r e u su a lly o p e ra te d on an in te rm itte n t sc h ed u le , ra d io a c tiv e i s o to p e s b e in g p ro d u c e d a s a b y -p ro d u c t . T h e s e r e a c t o r s a r e th e r e f o r e n o t a s w ell su ited fo r th e p re p a ra tio n of lo n g e r- liv e d a c tiv itie s th a t r e q u ire m o re continuous o p era tio n .

S h o r t- l iv e d is o to p e s a r e th e m o s t im p o r ta n t g ro u p of is o to p e s ap p lied in th e c h e m ic a l p ro c e s s in d u s try , if we d is r e g a rd se a le d so u rc e s at the m o m e n t. In o u r f ie ld , u n s e a le d r a d io a c t iv e s u b s ta n c e s a r e u s e d m a in ly f o r th e d e te rm in a tio n of flow r a te s and re s id e n c e tim e s in c h e m ic a l p lan t, such a s p ip es, ta n k s , and r e a c to r s . (H ere and in the follow ing th e te rm " re a c to r" n o rm a lly d e s ig n a te s no t a n u c le a r r e a c to r , bu t a v e s s e l in w hich c h e m ic a l r e a c t io n s a r e c a r r i e d ou t. ) S h o r t- l iv e d a c t iv i t ie s a r e p r e f e r r e d h e r e fo r tw o r e a s o n s : f i r s t , t h e r e a r e u s u a lly s e v e r a l m e a s u r e m e n ts to b e m a d eon one s y s te m w ith v a ry in g p ro c e s s p a r a m e te r s . S ho rt h a l f - l if e is a n e c e s s i ty in su c h c a s e s , o th e rw is e th e r e s id u a l a c tiv ity of th e f i r s t e x p e r im e n t w ill co m p lic a te th e fo llow ing ones. T he second re a s o n is th e co n tro l of p r o d u c t c o n ta m in a tio n . W hen an e x p e r im e n t h a s b e e n m a d e on a p la n t s c a le , th e a c tiv ity i s u su a lly d is p e rs e d in s e v e ra l to n s of va lu ab le p ro d u c ts . T h ese p ro d u c ts canno t be r e le a s e d fo r s id e o r f u r th e r p ro c e s s in g u n til th e a c tiv ity h a s d e c a y e d to s a fe le v e ls . A s h o r t h a l f - l i f e h e r e m e a n s l e s s s to r a g e c a p a c ity o c c u p ie d .

2. A C T IV IT IE S R EQ U IR ED F O R E X PE R IM E N T S IN CH EM ICA L PLA N TS

A ctua l m e a s u re m e n ts a r e so m e tim e s m ad e on sa m p le s d raw n f ro m th e la b e l le d c o n te n ts o f th e p la n t. M o re im p o r ta n t i s th e m e th o d of d e te c tin g th e p a s s a g e of a r a d io a c tiv e v o lu m e e lem e n t, th e s o -c a l le d la b e llin g p u lse , w ith a c o u n te r f ro m th e o u ts id e . F o r th is ty p e of m e a s u re m e n t , a h a rd 7 - e m i t te r i s n e c e s s a r y a s th e ra d ia t io n s o m e tim e s h a s to p e n e tr a te w a lls of p r e s s u r e v e s s e ls o r th e b r ic k lin in g of fu rn a c e s th ic k e r than 50 g /c m a . The a c t iv i t ie s r e q u i r e d f o r a flow e x p e r im e n t w ith e x te r n a l r e c o r d in g d ep en d

STUDIES IN THE CHEMICAL PROCESS INDUSTRY 251

on a n u m b e r of fa c to rs : b e s id e s w all ab so rp tio n , th e s e a re : s e lf-a b so rp tio n of th e r a d ia t io n in th e la b e l le d m a te r ia l , th e s o lid a n g le c o v e re d , and th e d e te c tio n e f f ic ie n c y of th e c o u n te r . T h e sp e e d of th e la b e l l in g p u ls e in th e p ip e s e ts th e u p p e r l im i t fo r th e tim e c o n s ta n t of th e r e c o r d e r . A s th is l ie s b e tw een a few te n th s of a seco n d and s e v e r a l se co n d s , su ff ic ie n t s ta t i s t i c a l a c c u r a c y ca n b e a c h ie v e d w ith c o u n t - r a t e s of th e o r d e r of K H /m in . T h e ab o v e -m en tio n ed f a c to rs , t r a n s m is s io n th ro u g h ab so rb in g la y e r s , g eo m etry and coun ting e ff ic ie n c y ra n g e f ro m 10-1 to 10 -4 . By m u lt ip lic a t io n of th e s e f a c to r s w e a r r iv e a t an o v e ra l l d e te c tio n e ff ic ie n c y b e tw e e n 1 0 - 8 and 1 0 - 8. B e tw ee n 1 an d 20 m e a r e r e q u i r e d fo r one flow e x p e r im e n t; in e s p e c ia l ly l a rg e p ie c e s of eq u ip m en t up to 100 m e m a y b e n e c e s s a r y . P ro d u c tio n of s h o r t- l iv e d ra d io iso to p e s in th is a c tiv ity ra n g e i s fe a s ib le in sm a ll r e s e a r c h

TABLE I

A C TIV ITIES FO R M ED IN F R F IN lg O F TA RG ET COMPOUND ( Ir ra d ia tio n : 8 h a t flux 3X1011n /c m 2 s)

Target

compound

Radioisotope

formed

H alf-life

(h)

Activity

(m c/g )

Na,CC^ Na!< 15 15

M n02 Mn56 2 .6 670

Gu C u64 12.8 80

NH4Br Br8! 36 11

LâjO j La140 40 32

r e a c to r s as is shown in T ab le I. We have chosen the d a ta of F R F (F o rsch u n g s- r e a k to r F ra n k fu r t) , the 50-kW hom ogeneous r e a c to r of F ra n k fu r t U n iversity , 8 h i r r a d ia t io n a t a th e r m a l flu x of 3 X10H n /c m 2 s . T h e a c t iv i t i e s f o rm e d in one g ra m of t a r g e t a r e g iven fo r so m e of th e com pounds u se d in o u r e x p e r im e n ts .

W ith th e f iv e ra d io iso to p e s l is te d in T ab le I we w e re ab le to so lv e m o s t p ro b le m s r e q u ir in g a 7 - e m i t te r a s t r a c e r . We have a lre a d y m en tio n e d th a t o u r w o rk c o n s is te d m a in ly in th e d e te rm in a tio n of f lo w - r a te , m ix in g t im e and d is trib u tio n s tu d ie s . P ro v id in g a su itab le sh o r t- liv e d 7 - e m itte r fo r th e se te c h n ic a l a p p l ic a tio n s i s r e n d e r e d e a s i e r by th e f a c t th a t , in c o n t r a s t to p u r e ly c h e m ic a l w o rk , one i s n o t c o n fin e d to a s in g le c h e m ic a l e le m e n t, a s i s show n b e lo w .

3. HETEROGENEOUS LABELLING: A PPLICATIO N TO SOLID AND LIQUID SYSTEMS

S e v e ra l of o u r p ro b le m s w e re so lv e d by u s in g la b e lle d p a r t i c le s w h ere s e le c t io n and h an d lin g of th e r a d io a c t iv e m a te r i a l a r e e s p e c ia l ly s im p le . T he la b e lle d p a r t ic le can be em ployed w here m ovem en ts of g ra in s o r pebb les a r e to b e fo llow ed . H e re th e r e q u ir e m e n ts of th e e x p e r im e n t a r e m e t if th e la b e lle d p a r t i c le i s s im i la r in g ra in s iz e , sp e c if ic g ra v ity and s u r fa c e p r o

252 K. FRDHAUF

p e r t i e s to th e so lid p a r t i c l e s s tu d ied . S u ffic ien t h a r d n e s s and h igh m e ltin g p o in t a r e f u r th e r q u a l i t ie s o ften re q u ir e d , w h ile th e c h e m ic a l n a tu re of the ra d io a c t iv e iso to p e i s of se c o n d a ry im p o r ta n c e . T h e in a c tiv e p a r t i c le s can b e conven ien tly p re p a re d b efo rehand and a su itab le e lem en t in c o rp o ra ted which w ill b e a c tiv a te d by n e u tro n i r r a d ia t io n . C h e m ic a l t r e a tm e n t of th e s h o r t liv e d a c tiv e su b s ta n c e i s th u s av o id ed and m e c h a n ic a l h a n d lin g re d u c e d to a m in im u m . Tw o e x a m p le s d e m o n s tr a te th e sc o p e of th i s m e th o d .

In a r o ta r y k iln , w h ere p y r ite is ro a s te d fo r su lp h u r dioxide production , w e w e re in te re s te d in th e e ffic ien cy of v a r io u s w e ir s and shove ls in th e k iln and th e in fluence of g ra in s iz e on p a r t ic le m ig ra tio n . A high m e ltin g m ix tu re of la n th an u m ox ide and so d iu m p h o sp h a te w as p r e p a re d , b ro k e n to th e r e q u ire d s iz e and i r r a d ia te d . T he g ra in s w e re in s e r te d in to th e k iln a t in te r v a l s of s e v e r a l h o u r s and e a c h s in g le g r a in w as t r a c k e d f ro m th e o u ts id e w ith a G -M tu b e and a r a t e - m e t e r by th e g a m m a s f ro m Lai40 and N a24. In an o th er in s ta n c e Lal4o w as u sed a s c o re in á coke p e lle t and, a f te r ac tiva tion , t h i s w a s em p lo y e d a s an in d ic a to r o f th e c i r c u la t io n t im e in a c r u d e o il c r a c k e r w h e re su c h co k e p e l le t s s e r v e a s a m e d iu m f o r h e a t t r a n s f e r .

T h e la b e lle d p a r t i c le , h o w e v e r, i s n o t r e s t r i c t e d to th e in v e s tig a tio n o f p a r t i c le m o v e m en t. In th e fo rm of a ho llow b a l l of p o ly p ro p y le n e i t a lso p ro v e d v a lu a b le fo r th e s tudy of liq u id flow . One h a lf of th e s p h e re i s f i l le d w ith th e la b e l l in g co m p o u n d , f o r in s ta n c e ,s o d iu m c a r b o n a te , m a n g a n e s e d ioxide o r lan th an u m oxide, to g ive N a24, Mn56' and Lai4o a c tiv i tie s r e s p e c t iv e ly . Som e le a d sh o t i s added to ad ju s t th e sp e c if ic g ra v ity and th e sp h e re i s se a le d by hea tin g .

In p ip e s w ithout s e v e re o b s tru c tio n s th e ve lo c ity of the liqu id w as d e te r m in ed in th is w ay. An im p o r ta n t advan tage of th is m e th o d i s th a t no ac tiv ity i s d is p e r s e d in to th e p ro d u c t. F ig . 1 show s a r e a c to r w h e re k in e tic s tu d ie s w e re m a d e w ith th e s a m e p o ly p ro p y le n e b a l ls . In th i s g a s - l iq u id c o n ta c to r th e liq u id i s r e c i r c u la te d b y g a s l if t in g and th e r e f o r e th e liq u id m o v e m e n t

6 0 s Outlet

Labelling Port

Fig-1

G as-liqu id reacto r w ith rec ircu la tin g liqu id phase

STUDŒS IN THE CHEMICAL PROCESS INDUSTRY 253

cannot be c a lc u la te d ex a c tly in advance . T h is type of r e a c to r i s en co u n te red fo r d if fe re n t ty p e s of c h e m ic a l r e a c t io n s . T he g as in tro d u c e d a t th e bo ttom is u su a lly one com ponent of a c h e m ic a l re a c tio n , th e liq u id m ay b e a second com ponen t, a c a ta ly s t so lu tio n , o r th e r e a c t io n p ro d u c t s e rv in g a s d ilu e n t. W ith th e la b e lle d s p h e re th e c irc u la t io n tim e of th e liq u id in th e r e a c to r can b e d e te rm in e d by r e g i s t e r in g c o n s e c u tiv e p a s s a g e s of th e a c tiv i ty . U n d e r fav o u rab le c irc u m s ta n c e s m o re than one thousand cy c le s have been re c o rd e d f ro m one p a r t i c l e , and th e in f lu e n c e of g a s flow on l iq u id c i r c u la t io n h a s b e e n s tu d ie d .

4 . H O M OGENEOUS L A B E L L IN G O F LIQ U ID SYSTEM S

To d e te rm in e th e liqu id conten t and m ixing tim e in th is type of g as-liq u id r e a c to r h o m ogeneous la b e ll in g of th e liq u id w as r e s o r te d to . In th e s e c a s e s a n a ly s is i s done in th e w ell-k n o w n m a n n e r of d ilu tio n a n a ly s is by coun ting sa m p le s d raw n f ro m th e liq u id a t r e g u la r in te rv a ls u n til th e sp ec ific ac tiv ity of th e liq u id b ec o m e s co n stan t.

F o r h o m o g en eo u s la b e ll in g th e p h y s ic a l and c h e m ic a l b e h a v io u r of th e a c t iv i ty in th e r e a c t io n m ix tu re m u s t b e c o n s id e r e d m o r e c a r e f u l ly . B u t ev en h e r e i t i s n o t u s u a lly n e c e s s a r y to in je c t an iso to p e of one of th e e l e m e n ts co n ta in e d in th e r e a c tio n m ix tu re . F o r in s ta n c e , B r 82, a s anh y d ro u s a lu m in iu m b ro m id e , w as su c c e ss fu lly em ployed a s la b e l fo r h ig h ly - re a c tiv e a lu m in iu m o rg a n ic co m p o u n d s , su c h a s t r ie th y l- a lu m in iu m . T o a r r i v e a t u n b ia se d r e s u l t s tw o c o n d itio n s a r e e s s e n t ia l : fu lly h o m o g e n eo u s d i s t r i b u tio n of th e la b e ll in g com pound in th e m e d iu m s tu d ied , and n e g lig ib le a d so rp tio n by th e w a lls of th e re a c tio n v e s s e l . T he l a t te r r e q u ire m e n t i s m o st im p o rta n t fo r d e te rm in a tio n of re s id e n c e tim e d is trib u tio n in a re a c to r w here th e liq u id i s n o t r e c i r c u l a t e d b u t p a s s e s o n ce th ro u g h a tu b e s y s te m , a s Shown in F ig . 2. In th e s e r e f in e d flow m e a s u r e m e n ts a r a d io a c t iv e t r a c e r i s in je c te d in s tan ta n eo u s ly in a sm a ll vo lum e a t th e beg inn ing of th e re a c tio n zone. P a s s in g th ro u g h th e re a c tio n tube th e ac tiv ity is s p re a d o v er a c e r ta in

I Labelling * Port

CountRote

-► Time

F ig .2

D eterm ination o f residence t im e distribution in a tiibe reacto r

254 K. FRÜHAUF

v o lu m e by d iffu s io n and b a c k m ix in g . A c o u n te r r e c o r d s th e p u l s e - r a t e as v a ry in g w ith tim e , a t in te rm e d ia te po in ts , and a t the end of the re a c tio n zone.. T he r e s u l t in g p lo t of c o u n t- ra te a g a in s t t im e , a f te r th e p ro p e r ad ju s tm en t of scelles, d ir e c t ly y ie ld s th e r e s id e n c e t im e d is tr ib u tio n , i. e . th e p e rc e n ta g e of th e v o lu m e in tro d u c e d re m a in in g a g iven t im e u n d e r r e a c tio n co n d itio n s .

L e a k d e te c tio n an d d is t r ib u t io n s tu d ie s a r e f u r th e r e x a m p le s f o r th e ap p lic a tio n of s h o r t- l iv e d iso to p e s fo r th e hom ogeneous la b e ll in g of liq u id s . P o o r r e s u l t s w e re ob ta ined w ith rad io io d in e , when d is tr ib u tio n of th e dow ns tr e a m liq u id in a s ta in le s s s te e l ab so rp tio n to w er w as in v e s tig a ted . A la rg e am oun t of th e io d id e a c tiv i ty w as a d s o rb e d on to th e w a lls and p la te s of th e to w e r . S w itch in g to L a 140 a s c a tio n ic t r a c e r im p ro v e d th e s i tu a t io n .

In e x p e r im e n ts w ith N a24 i t w as u se d in one c a se a s iso to p ic t r a c e r fo r so d iu m c h lo r id e in sy n th e tic d y es tu ff c a k e s . T h e e ff ic ie n c y of th e w ash in g c y c le s in a f i l t e r p r e s s w as ch eck ed h e r e by coun ting s a m p le s d raw n f ro m th e liq u id o u tle t an d f ro m s e le c te d p o s i t io n s in th e r e c o v e r e d f i l t e r c a k e .

5. A Bal37m G E N E R A T O R F O R ORGANIC LIQ U ID M ED IA

W hen la b e l l in g th e c i r c u la t in g l iq u id of a g a s - l iq u id r e a c t o r s im i l a r to th a t show n in F ig . 1, w e w e re in te r e s te d in th e h o m o g e n e o u s la b e l l in g of a high b o ilin g o rg a n ic m ed iu m . F u r th e r re q u ire m e n ts w ere sm a ll volum e of th e la b e ll in g p u lse and sh o r t in te rv a ls b e tw een p u lse s . As a la b e l fo r th is we se le c te d B ai37m t a 7 - e m i t te r w ith a h a lf - life of 2. 6 m in . Due to i t s sh o rt h a lf - l if e , th is a c tiv ity m u s t b e p ro d u ce d by an iso to p e g e n e ra to r a t th e s ite of th e e x p e r im e n t. S ta r tin g m a te r ia l f o r th e p r e p a ra t io n of Bai37m a c tiv ity i s th e f i s s io n p ro d u c t C si37 , w h ich d e c a y s by 0 - e m is s io n w ith a h a l f - l i f e of 27 y r , to s ta b le B a131, F ig . 3. H ow ever, th is Э-d ec ay le a d s with 92% abundance to an ex c ite d s ta te of B a i37, m e ta s ta b le Ba137tawith a 2. 6 -m in h a lf - life .

Form ation and Decay o f B al37m

Is o m e r ic tr a n s i t io n of th is ex c ited s ta te to the ground s ta te r e s u l t s in em issio n of th e 0. 6 6 M eV т - r a y n o r m a l ly a t t r ib u te d to th e m o th e r s u b s ta n c e C s i3 7 , w hich u su a lly co n ta in s th e B a l37m in e q u ilib riu m . E m ploying a fa s t ch em ica l s e p a ra tio n m e th o d th is 7 - e m it te r can be o b ta in ed a p a r t f ro m i t s lo n g - liv e d p a r e n t . In 1961 GWYN d e s c r ib e d th e in d u s t r ia l a p p lic a tio n of a g e n e r a to r w hich d e l iv e re d B a137m in aq u eo u s so lu tio n , th e C s537 b e in g a d s o rb e d on an io n e x c h a n g e co lu m n [1 ]. A s w e n e e d e d th e a c t iv i ty in an o rg a n ic s o lv e n t th e e x tra c tio n b e h a v io u r of B a w as s tu d ied . D uring th e 1958 G eneva C o n fe r


en c e a J a p a n e s e te a m r e p o r te d on th e e x t ra c t io n of S r by 0. 05 M T T A (T h e n o y l- tr ii 'lu o ro -a ce to n e )in h ex o n e (M eth y l-iso b u ty l-k e to n e ) 12]. We adapted th is m ethod fo r th e se p a ra tio n of B a f ro m C s.

B a137m is e x tra c te d in to a 0. 05-M so lu tio n of T T A in a c e to p h e n o n e co n ta in in g 20% of a h y d ro ca rb o n d iluen t of bo ilin g point 200°C. B e s id e s the Cs137 a c tiv ity , th e aqueous p h a se c o n ta in s 1 m g C s /m l a s h o ld -b a c k c a r r i e r and 10% N aC l to in c re a s e th e sp e c if ic g ra v ity . T h is im p ro v e s p h a se s e p a ra tio n , andpH 9 i s m a in ta in ed by a b o ra te b u ffe r. C ontacting w ith an equal volum e of e x t ra c ta n t y ie ld s 70% of th e т -a c tiv ity in th e o rg a n ic p h ase , w ith Cs>37 co n ta m in a tio n below 1% of e x tra c te d B ai37m . O p era tio n of th e e x tra c tin g d ev ice is shown in F ig . 4. T he aqueous p h ase (20 m l) re m a in s in a polythene cy lin d e r

Fig. 4

B al37m generator

in s id e a sh ie ld in g co n ta in e r. A fter th e addition of 20 m l ex tra c ta n t the p h ases a r e m ix e d by 10 up-and-dow n s t r o k e s w ith an a g ita t in g ro d c a r ry in g a d isc of w ire g au ze a t i t s lo w e r end. O ne m in u te a f te r th e end of m ix in g a m a n ip u la to r p ip e tte i s in s e r te d and th e d rg a n ic p h a se d raw n up. B etw een 10 and 20 m e C s137 w ere em ployed fo r y ie ld s of 5 to 10 m e B a 137m. An e x tra c tio n can be m a d e e v e ry 10 m in ; a f te r th a t t im e o v e r 90% of th e e q u ilib r iu m a c tiv ity of Bai37m h a s g ro w n in . B e tw ee n f iv e and te n e x t r a c t io n s a r e o b ta in e d f ro m one b a tc h of a q u e o u s p h a s e , a f te r w h ich th e b u f fe r c a p a c ity h a s b e e n e x h a u s te d b y th e a c id ic e x t r a c ta n t , and e x t r a c t io n e f f ic ie n c y d r o p s to 10%. In o u r e x p e r ie n c e b e tw een f iv e and e ig h t e x tra c tio n s w e re su ffic ie n t fo r one p la n t e x p e r im e n t; a f te rw a rd s th e С s i37 a c tiv i ty i s e a s i ly r e c o v e r e d in th e la b o r a to r y by p r e c ip i ta t io n a s p h o sp h o tu n g s ta te . A fte r d is s o lu tio n in NaOH i t ca n b e r e - u s e d in a new s e t of e x p e r im e n ts .

T h is e x a m p le of th e a p p lic a tio n of an iso to p e g e n e r a to r d e m o n s tr a te s th a t n o t only r e a c to r -p ro d u c e d , bu t g e n e ra lly s h o r t- l iv e d ra d io iso to p e s a r e a m o s t v a lu ab le to o l fo r p lan t e x p e r im e n ts in th e c h e m ic a l p ro c e s s in d u stry .

256 K. FRtJHAUF

R E F E R E N C E S

[1] GWYN, I. E . , Fast Response pulse Tests use gam m a M ilking, Ind . Eng. C h em . 53 (1961) 907.[2] NOBUFUSA SAITO e t a l . , R adiochem ical Studies o f fissile and fission-produced Elem ents, Proc. 2nd

UN In t. C onf. , PUAE 20 (1958) 199.

D I S C U S S I O N

H. S ORAN TIN: W hat te m p e r a tu re d id you m a in ta in in y o u r liq u id -g a s r e a c to r w hile u s in g p o ly e th y le n e -c o v e re d b a l ls co n ta in in g the ra d io n u c lid e . We found tha t p o ly e th y le n e -c o v e re d b a l ls w ea r out v e ry fa s t in tube sy s tem s .

K . F R Ü H A U F : We u s e d p o ly p ro p y le n e b a l l s up to 40°C . F o r h ig h e r t e m p e r a tu r e s p o ly e s te r r e s in s ( P a la ta l , B A S F L u d w ig sh afe n ) w e re u s e d .

R . W OLF: W ith w hat a c c u ra c y do you think you can d e te rm in e the flow- r a t e s in y o u r e x p e r im e n ts on the p a s s a g e tim e of la b e lle d e le m e n ts in y o u r r e a c to r tu b es ?

K. FRÜ HA U F: In the c a s e of hom ogeneous liq u id la b e llin g by in je c tio n of Bai37m we h a d a d is ta n c e o f s ix m e t r e s b e tw e e n the c o u n te r s an d v e lo c i t ie s up to 0 .5 m / s . T h e p a s s a g e o f the liq u id p u ls e co u ld b e tim e d w ith a n a c c u r a c y o f ± 1 s . T h is le d to a n u n c e r ta in ty of ± 10% f o r th e v e lo c ity o f the liq u id .

W .W . M EIN K E: We h a v e h e a r d o f m a n y in te r e s t in g in d u s t r ia l a p p l i c a tio n s of ra d io is o to p e s th is m o rn in g , and I shou ld lik e to a sk M r. F rü h a u f an d M r. E rw a l l to co m m e n t on th e k in d of : r e g u la t io n s w hich a r e in f o rc e fo r s h o r t - l iv e d r a d io is o to p e s in th e ir r e s p e c t iv e c o u n tr ie s .

К . FRÜ HA U F: In the F e d e r a l R ep u b lic of G erm a n y we have no s p e c ia l re g u la tio n s fo r the u s e of s h o r t- l iv e d iso to p e s . L ab e lle d m a te r ia ls ob ta ined f ro m an in d u s t r ia l t r a c e r e x p e r im e n t m u s t b e w ith in the l im its im p o se d by the IC R P re c o m m e n d a tio n s fo r d rin k in g w a te r . E v e n i f we fu lf i l th e se r e q u ir e m e n ts th e re i s o ften a c e r ta in o p p o s itio n to b e o v e rc o m e on the p a r t o f the p eo p le w o rk in g in the p la n t, b u t once they b ec o m e f a m i l ia r w ith o u r m e th o d s an d r e s u l t s , w ork b e c o m e s e a s ie r . We co n d u c ted a l l our, e x p e r i m e n ta l s tu d ie s in p la n ts b e lo n g in g to o u r ow n f i r m , w h ich o f c o u r s e w as a n a d v a n ta g e .

L . G . E R W A L L : T h e u s e of r a d io is o to p e s in S w eden i s r e g u la te d b y a ra d ia t io n p ro te c t io n law . G e n e ra lly sp e ak in g , only r a d io is o to p e s c l a s s i fied in IC R P g ro u p s С an d D a r e a llow ed a s t r a c e r s , and the d rin k in g w a te r to le ra n c e s a r e ap p lied to the f in a l p ro d u c ts . If th e se cond itions a r e fu lfilled , a lic e n c e can b e ob ta ined f ro m the a u th o r i tie s , p ro v id ed the p e rso n re s p o n s ib le fo r the w ork i s su f f ic ie n tly tr a in e d in iso to p e te ch n iq u e s an d r a d ia t io n p ro te c tio n . T h e re is no le g a l ban on the u se of rad io iso to p es in, fo r exam ple , the food in d u s t ry . T h u s , r a d io is o to p e s w e re u s e d to s tu d y the g r a in - s i z e o f s u g a r an d the s u g a r w as s o ld o v e r the c o u n te r a f te rw a rd s .

W. W. M EINKE: I th ink in th e U n ited S ta te s th e re is a ls o a p u b lic r e la tio n s p ro b le m in connection w ith the food in d u stry . T h ere a r e c e r ta in s te e l co m p an ies w hich a t p r e s e n t w ill no t c o n s id e r t r a c e r s b e c a u se so m e of th e ir s te e l en d s up in food c a n s , an d the p la s t ic s in d u s try p eo p le h av e a s im i la r


p r o b le m . I a m v e r y in te r e s te d . t o know th a t you h av e u s e d is o to p e s in the food in d u s t ry in S w eden .

L . G . E R W A L L : In th is c o n n e c tio n I sh o u ld s a y th a t w e a t ta c h g r e a t im p o r ta n c e to the in fo rm a tio n w e g e t f r o m th e la b o u r u n io n s on r a d ia t io n p r o te c t io n . O u r c o n ta c ts w ith the la b o u r u n io n s a r e v e r y good .

W . W . M E IN K E : T h a t i s v e r y im p o r ta n t .K. FR Û H A U F: O ne d iffic u lty we e n c o u n te re d w as th a t o ften we cou ld

n o t e v e n m a k e u s e of th e le v e ls p e r m i t te d , b e c a u s e o f th è c o n c e rn of th e p e o p le in v o lv e d in th e w o rk , b u t o n ce th e y b e c a m e f a m i l i a r w ith i t th in g s b e c a m e m u c h e a s i e r .

STUDIES OF POWDER MIXING WITH SHORT-LIVEDRADIOISOTOPES

I. BJERLETHE STOCKHOLM SIPOREX MANUFACTURING COMPANY, SÔDERTALJE

AND H. G. FORSBERG ISOTOPE TECHNIQUES LABORATORY, STOCKHOLM, SWEDEN


STUDIES OF POWDER MIXING WITH SHORT-LIVED RADIOISOTOPES. Many industrial processes involve th e m ixing o f powders to form homogenous products. If the m ix ing conditions a re not w ell established the m ixing units w ill not be used to the ir best advantage.

M any m ixing problems can be studied by m eans of ch em ica l analysis, but a series of such analyses'is expensive in comparison with the fast and cheap m easurem ent of rad ioactiv ity . For this reason radioisotopes are often used in determ ining optim um m ixing conditions. The s ta tis tica l nature of rad ioactive decay also sim plifies the treatm ent of the data obtained. The theory and application of some useful sta tistica l methods are described.

As an exam ple, the m ixing of light concrete from cem ent powder, alum inium powder, sand and water is described. This is a severe m ixing problem as m ixing m ust occur before the reaction betw een w ater and alum inium , which gives the typical light-concrete structure, takes place to any considerable extent. Samples of a lum inium powder and cem en t powder a re activated in a reactor and are then used as radioactive tracers for the 5 m 3 batches of m ixture. The behaviour of the a lum inium powder is studied using the nuclide M n5® which is produced from m anganese im purities in the alum inium . If certa in precautions are taken it is possible to use this nuclide in spite o f its short h a lf - l ife (2. 6 h). In the case of c em en t powder, use is m ade o f the nuclides Na24 and K4* which a re form ed in this m a te ria l.

ETUDES DU MÉLANGE DES POUDRES AU MOYEN DE RADIOISOTOPES A COURTE PÉRIODE. De nombreux procédés industriels nécessitent le m élange de poudres pour l'obtention de produits homogènes. Si l ’on ne connaît pas bien com m ent se fa it le m élange on ne pourra pas u tiliser les m élangeurs dans les m eilleures conditions.

Il est possible d ’étudier de nombreux problèmes de m élange par analyse chim ique, m ais le coût d ’une série d 'analyses chim iques est é lev é par rapport â c elu i de la m esure de la rad io ac tiv ité , qui e st rap ide e t peu onéreuse. C 'est pourquoi les radioisotopes sont souvent utilisés pour déterm iner les conditions optim a de m élange. Le carac tère statistique de la désin tégration radioactive sim plifie aussi le tra item en t des données obtenues. Les auteurs p résentent la théorie e t l ’a p p lica tio n de quelques m éthodes statistiques u tile s .

Ils décriven t, com m e exem ple, le m élange de c im en t en poudres, de poudre d 'a lu m in iu m , de sable--' e t d 'e au qui donne le béton léger. La préparation de ce béton pose un problème difficile parce que le mélange do it se fa ire avan t que la réaction entre l ’eau e t l'a lum in ium - qui donne au béton léger sa structure p a rticu liè re - n ’a it a t te in t un degré é lev é . Des échan tillons d 'a lu m in iu m e t de c im en t en poudre sont activés dans un réacteur, puis utilisés comme indicateurs dans les mélangeurs qui traitent des lots de 5 m3. Le comportem ent de la poudre d ’alum inium est é tud ié par l 'in te rm éd ia ire du nucléide 56Mn qui est produit â partir du m anganèse se trouvant 2 l 'é ta t d 'im puretés dans l 'a lum in ium . En dép it de sa courte période (Ti = 2 ,6 h), il est possible d 'u tilise r ce nucléide avec succès, m oyennant certa ines précautions. Pour é tudier là poudre de c im en t, on u tilise les nucléides 24Na e t 42K qui s 'y form ent.

ИССЛЕДОВАНИЕ СМЕШЕНИЯ ПОРОШКОВ С ПОМОЩЬЮ КОРОТКОЖИВУЩИХ РАДИОИЗОТОПОВ. Многие промышленные, процессы связаны со смешением порошков с целью образования гомогенных продуктов. Эффективное использование установки для смешения зависит от того, насколько хорошо известны условия смешения.

Многие проблемы смешения могут быть изучены посредством химического анализа, но проведение серии таких анализов слишком дорого по сравнению с быстрым и дешевым измерением радиоактивности. Поэтому для определения оптимальных условий смешения часто используются радиоизотопы. Статистический характер радиоактивного распада упрощает также обработку подученных данных. Описывается

теория и применение некоторых статистических методов.

259

260 I. B JE RLE

В качестве примера описывается смешение легкого бетона из порошка цемента, порошка алхшиния, песка и воды. По условиям процесса смешение должно произойти до реакции между водой и алхминием, которая дает типичную структуру легкого бетона в значительном числе случаев. Образцы порошка алшиния и цемента активируются в реакторе и затем используются в качестве радиоактивных индикаторов для порций смеси объемом в 5 мэ . Поведение порошка алшыиния изучается с помощью радиоизотопа Мп5в, который образуется из примесей марганца в порошке алюминия. Если соблюдаются определенные меры предосторожности, можно с успехом использовать этот радиоизотоп, несмотря на его короткий период полураспада (2 ,6 час).Для порошка цемента используются радиоизотопы натрий-24 и калий-42, которые образуются в результате активации.

ESTUDIOS DE LA MEZCLA DE SUSTANCIAS PULVERULENTAS CON RADIOISOTOPOS DE PERIODO CORTO. Muchos procesos Industriales suponen la m ezcla de sustancias pulverulentas para obtener un producto homogéneo. Ahora b ien , para que los aparatos alcancen un rendim iento óptimo es preciso conocer cabalm ente las condiciones de l proceso de m ezcla.

El análisis químico perm ite estudiar numerosas problemas de m ezcla, pero resulta oneroso en comparación con la m edición de la rad iac tiv idad , que es rápida y económ ica. Por e llo , los radioisótopos se em plean con frecuencia para determ inar las condiciones óptim as de m ez c la . Además, e l carác te r estadístico de la desintegración radiactiva sim plifica e l análisis de los datos obtenidos. La m em oria describe la teoría y la aplicación de algunos métodos estadísticos u tilizables en la práctica.

Como ejem plo , se describe la m ezcla de horm igón ligero com puesto de cem ento en polvo, polvo de a lum in io , arena y ag u a . Constituye un problem a d ifíc il porque la m ezcla ha de quedar term inada antes de que la reacción entre e l agua y e l alum inio, que confiere a l hormigón ligero su estructura típ ica,esté demasiado avanzada. Se activan en un reactor muestras de alum inio en polvo y de polvo de cem ento y se u tilizan como indicadores radiactivos para las cargas de 5 m3 de m ezcla . Los m ovimientos de l alum inio en polvo se estudian gracias a l núclido ^M n que se forma a partir del manganeso que impurifica este m etal. A condición deadoptar ciertas precauciones, es posible em plear este núclido a pesar de su breve período (2 ,6 h). En e l caso del polvo de cem ento, se u tilizan los niiclidos 24Na y « К que se forman en este componente.

M any in d u s t r ia l p r o c e s s e s in v o lv e th e m ix in g of l iq u id s , p o w d e rs o r p a s te s in to a h o m o g e n eo u s p r o d u c t . S uch o p e ra t io n s g e n e r a l ly ta k e a c o n s id e ra b le tim e and if con d itio n s a r e not w ell e s ta b lish e d b a tch m ix e r s m u st, to e n s u re a d e q u a te m ix in g , w o rk f o r u n n e c e s s a r i ly lo n g p e r io d s , o r c o n tin u o u s m ix e r s a r e d im en sio n ed to u n n e c e s sa r ily long r e s id e n c e tim e s . T h is m a y c a u s e a low r a t i o of p ro d u c tio n to c a p a c ity and w ith th a t , a d e c r e a s e in p r o c e s s eco n o m y .

M any m ix in g o p e ra tio n s can b e fo llow ed by c h e m ic a l d e te rm in a tio n of one o f th e c o m p o n e n ts . W ith o th e r m ix tu re s , f o r in s ta n c e th o s e o f c h e m ic a l ly r e la te d co m p o n en ts , o r te c h n ic a l p ro d u c ts o f in d e fin ite c o m p o s itio n , a n a ly s is i s d ifficu lt o r im p o ss ib le to p e r fo rm . A g e n e ra l d isadvan tage of ch em ica l a n a ly s i s i s th e t im e and e f fo r t in v o lv e d in m e a s u r in g l a r g e s e r i e s of s a m p le s . A s r a d io a c t iv i ty i s c h e a p ly and e a s i ly m e a s u r e d , r a d io a c t iv e t r a c e r s a r e of g r e a t v a lu e fo r d e te rm in in g op tim um con d itio n s fo r a m ix ing o p e ra tio n .

M any ra d io a c tiv e m ix ing s tu d ie s a r e d e sc r ib e d in th e l i t e r a tu r e . T yp ical e x a m p le s of m ix in g liq u id s c a n b e found in th e w o rk of H U L L e t a l. [1 ], of p a s te s (e. g. soap) in w ork by KUHN, rev iew ed by H U LL e t a l. [ 2], and ru b b e r d e s c r ib e d by ANDERS 13]. F u r th e r e x a m p le s ca n be ta k e n f ro m m ix in g co a l p ow der 14J, S ô d e rb e rg e le c tro d e s 15], c e m e n t s lu d g e [6, 7], c a tt le feed [8], w ash in g p o w d er [9] and s o lid p ro p e lla n ts [10]. S h o r t- l iv e d ra d io a c tiv e t r a c e r s w e re a p p lie d in m o s t of th e s e c a s e s . P o w d e r m ix in g i s d is c u s s e d in so m e d e ta il in th is p a p e r and one s u ita b le w ay o f t r e a t in g r e s e a r c h d a ta i s d e s c r ib e d . T h is i s g e n e ra lly a p p lic a b le to o th e r c a s e s .

STUDIES OF POWDER MIXING WITH SHORT-LIVED RADIOISOTOPES 261

TIME

Fig. 1

T yp ica l ac tiv ity -tim e curve ob ta ined in a m ixing experim ent

O ne m ethod of in v e s tig a tin g a m ix ing p ro c e s s , w hich is often applied , is to ta k e f re q u e n t s a m p le s f ro m one o r s e v e ra l p o in ts of a m ix e r . U nder s u i t ab le co n d itio n s a c u rv e w ill th e n be ob ta ined s im i la r to th a t show h in F ig . 1.

W hen th e s a m p le s show c o n s ta n t a c tiv i ty , o r c h e m ic a l c o m p o s it io n , c o m p le te m ix in g i s c o n s id e re d to h a v e b e e n o b ta in ed . B oth s t a t i s t i c a l and p r a c t ic a l o b je c tio n s can b e r a is e d a g a in s t th is m ethod . I t i s th e re fo re b e t te r to ta k e s a m p le s l e s s f re q u e n tly bu t a n u m b e r of s a m p le s e a c h t im e .

F o r each t im e , th e a v e ra g e v a lu e of ac tiv ity (x) of th e group of sa m p le s i s d e te rm in e d and th e s ta n d a rd d e v ia tio n (s) i s c a lc u la te d a c c o rd in g to th e fo rm u la

w h ere x i s th e s in g le v a lu e and n th e n u m b er of sa m p le s ; F ro m th e se c a lc u la tio n s a d ia g ra m can be c o n s tru c te d , a s show n in F ig . 2.

S

о<

>->

TIME

Fig-2T yp ica l d ev ia tio n -tim e curve bb tained in a m ix ing experim ent

262

Log s

I. B JE RLE

Fig.3

Log s versus tim e curve used to determ ine tim e for adequate m ixing

M ixing can be c o n s id e re d co m p le te when th e s ta n d a rd d ev ia tion i s co n sta n t . T he end p o in t can a lso b e d e te rm in e d , e i th e r g ra p h ic a lly o r s t a t i s t ic a l ly . W ith th e g ra p h ic m e th o d , th e lo g a r i th m of s o r s 2 i s show n a g a in s t t im e and th e t im e fo r a d e q u a te m ix in g i s d e te rm in e d a s th e p o in t of i n t e r s e c tio n of th e tw o s t r a ig h t l in e s . T h is i s show n in F ig . 3.

C om plete hom ogeneity a p p e a rs n e v e r to be re a c h e d (F ig s 2 and 3). T h is m ay b e b ec au se co m p le te m ix ing is not p o ss ib le in the equipm ent u n d er study, bu t in m o s t c a s e s th is r e s u l t i s due to th e fa c t th a t e v e ry m e th o á of a n a ly s is h a s a c e r ta in f a c to r of u n c e r ta in ty . W hen c h e m ic a l a n a ly s is i s app lied , th e m agn itude of th e u n c e r ta in ty m ay be d ifficu lt to a s s e s s ; in ra d ia tio n m e a s u re m e n t i t ca n be d e te rm in e d w ith s im p le s ta t i s t i c a l m e th o d s . T h e s ta t i s t i c a l m e th o d s can a lso b e u se d to d ec id e if th e d e g re e of m ix in g o b ta in ed can be c o n s id e re d to r e la te to co m p le te m ix in g o r no t.

T he n u m b e r of d ec ay in g n u c le i in a r a d ia tio n s o u rc e p e r u n it t im e , a s w ell a s th e n u m b e r of im p u lse s re c o rd e d on a d e te c to r re s u lt in g f ro m th e se d e c a y s , a r e d is t r ib u te d a c c o rd in g to a b in o m ia l d is t r ib u t io n w h ich , w hen m e a s u r in g ta k e s p la c e fo r a t im e s h o r t in c o m p a r iso n w ith th e h a l f - l i f e of th e n u c lid e , can b e a p p ro x im a te d to a P o is s o n d is t r ib u t io n . F u r th e r , th is d is t r ib u t io n w ith in c r e a s in g n u m b e r of e v e n ts p e r u n it t im e a p p ro x im a te s to a G a u s s ia n d is t r ib u t io n . T h u s th e n u m b e r of im p u ls e s r e c o rd e d in a c e r ta in tim e fo llow s a n o rm a l d is tr ib u tio n w ith a s ta n d a rd deviation (a) w hich i s e q u a l to t h e 's q u a r e r o o t of th e n u m b e r of r e c o r d e d im p u ls e s [11, 12].

W hen a m ix tu re i s h o m o g e n eo u s , s sh o u ld b e eq u a l to cr. A s h o w e v e r th e d e v ia tio n i s d e te rm in e d f ro m a l im ite d n u m b e r of m e a s u re m e n ts , one can e x p e c t i t to adop t v a lu e s w hich , w ith in c e r ta in l im i t s , a r e g r e a t e r o r s m a l le r th a n a, ev en if th e m ix tu re i s h o m o g en eo u s. T h e q u o tie n t b e tw een s 2 and cr2 fo llo w s th e s o - c a l le d X '^ /d f-d is trib u tio n [13]. It ca n b e found f ro m ta b le s th a t if s i s b a se d upon s ix m e a su re m e n ts , th e v a lu e of the quo tien t w ill f a l l n ine t im e s out of te n w ith in th e in te rv a l 0. 23 -2 . 2. V alues of th e quotient s m a l le r th a n 0. 23 m u s t , h o w ev e r, have th e p h y s ic a l m e a n in g th a t a h o m o geneous m ix tu re i s ob ta ined . To put th is an o th er way, if r e p e a te d m e a s u r e


m e n ts a r e m a d e on s ix s a m p le s f ro m a h o m ogeneous m ix tu re , th e q u o tien t w ill b e s m a l le r th a n 2. 2 in 95% of a l l c a s e s and only in 5% w ill i t b e m o re th a n 2 . 2 . W hen th e r e f o r e i t i s s ta te d th a t a m ix tu re i s n o t h o m o g e n e o u s , b a s e d upon a v a lu e h ig h e r th a n 2. 2, th e p o s s ib il i ty of th is s ta te m e n t b e in g w ro n g i s l e s s th a n 5%. T h e g r e a te r th e n u m b e r of s a m p le s on w h ich th e d e te rm in a tio n of s i s b a s e d , th e s m a l le r w ill be th e in te r v a l in to w hich th e q u o tie n t can fa ll a t th e s a m e le v e l of s ig n ific a n c e .

S om etim es , how ever, a hom ogeneous m ix tu re can a lso show d isp e rs io n s g r e a t e r th a n ст. T h is c a n b e f o r s e v e r a l r e a s o n s , su c h a s in f lu e n c e f ro m b ack g ro u n d ra d ia tio n , in s ta b il i ty of m e a s u r in g equ ipm en t, e r r o r s in sa m p lin g an d th e p r e s e n c e of to o few r a d io a c t iv e g r a in s in th e m e a s u r e d s a m p le .

E v e r y n u c le a r r a d ia t io n c o u n te r h a s a b a c k g ro u n d c o u n t - r a t e c a u s e d by co sm ic r a y s and n a tu ra l ra d io a c tiv ity . The to ta l counting r a te ( r t ) is com p o s e d of one c o n tr ib u tio n f ro m th e s a m p le ( r s ) and one c o n tr ib u t io n f ro m b a c k g ro u n d ( r b). T h e n e t a c tiv i ty f ro m th e s a m p le i s r s = r t - rb, an d f o r th e s ta n d a r d d e v ia tio n th e fo llo w in g f o rm u la i s v a lid :

If r s i s m u ch g r e a te r th a n r b, no c o r r e c t io n fo r b a c k g ro u n d i s n eed ed . If th is r e q u i r e m e n t i s n o t m e t, ct m u s t b e r e p la c e d f ro m th e b e g in n in g by <ts. In s e p a r a te m e a s u re m e n ts crb i s d e te rm in e d . C o r re c tio n s fo r th e d ec ay of th e r a d io a c tiv e t r a c e r a r e b e s t m a d e b e fo re c a lc u la tin g s .

T h e re p ro d u c ib i li ty of th e m e a s u r in g equ ipm en t i s ch eck ed by re p e a te d m e a s u r e m e n ts on th e s a m e s a m p le . T h e d e v ia tio n i s c o m p a re d w ith ct a c c o rd in g to th e X2/ d f - t e s t a l r e a d y d e s c r ib e d .

A check m u st be m ade , if p o ss ib le , to s e e th a t com pounds a r e not s e p a ra te d when sa m p lin g b ec au se of u n su itab le d es ig n of sa m p lin g d e v ic e s . Such s e p a ra tio n can o c c u r if i t i s n e c e s s a r y fo r m a te r ia l co n ta in in g p a r t i c le s of of v a r io u s sh a p e s and d e n s ity to f a l l a lo n g w ay th ro u g h a tu b e o r th e open a i r . S e v e ra l s im i l a r e f f e c ts c a n c a u s e e r r o r s in s a m p lin g te c h n iq u e s .

A se r io u s ca u se of la rg e d ev ia tio n s is th a t th e re a re too few rad io a c tiv e g r a in s p r e s e n t in th e s a m p le b e in g m e a s u re d . T h e n u m b e r of g r a in s in a s in g le s a m p le w ill, a t h o m ogeneous m ix ing , fo llow a P o is so n d is tr ib u tio n , a s d o e s r a d io a c t iv e d e c a y and i t h a s t h e r e f o r e a s ta n d a rd d e v ia tio n eq u a l to the s q u a re ro o t of th e a v e rag e nu m b er of g ra in s [14]. A check m u s t th e r e f o re b e m a d e th a t th e n u m b e r of r a d io a c t iv e g r a in s in a s a m p le e x c e e d s10 000 f o r th e s ta n d a r d d e v ia tio n f ro m th i s to b e l e s s th a n 1. 0%, e tc .

If i t i s found th a t ev en h o m o g e n eo u s m a te r i a l g iv e s c o n s id e ra b le d i s p e rs io n due to th e s o u rc e s of e r r o r d e s c r ib e d above, and th is cannot be r e d u ce d to a n e g l ig ib le m a g n itu d e , th e Xz- t e s t w ill no lo n g e r b e a p p lic a b le . In s tea d , a s o -c a l le d F - t e s t m u s t be app lied , w h ere tw o s ta n d a rd d ev ia tio n s s and Sj a r e c o m p a re d , s 1 b e in g th e s ta n d a r d d e v ia tio n d e te r m in e d f o r a h o m o g e n eo u s m a te r i a l in th e a c tu a l m e a s u r in g eq u ip m en t. T h e h ig h e s t p e r m is s ib le v a lu e s of th e q u o tie n t s 2/s ^ a t a 95% le v e l o f s ig n i f ic a n c e i s show n in T a b le I.T he co m p le te T ab le can be found in m o st s ta t is t ic a l te x t-b o o k s . A t an in fin ite n u m b e r o f d e te r m in a t io n s of s x th e d is t r ib u t io n w ill p r o c e e d to X2/d f .

If one of th e com pounds i s ch o sen a s t r a c e r , a s m a ll q u an tity i s i r r a d ia ted in a r e a c to r u n d e r con d itio n s w hich fav o u r th e fo rm a tio n of a su itab le

TABLE I

NUM BER O F M EASUREM ENTS ON WHICH s IS BASED

264 I- BJERLE

g2 4 6 8 10 20

о

соtaи

2 161 216 230 237 241 248

В0)mЛ 4 10.1 9 .3 9 .0 8 .9

0000 8 .6з •S3<4 «Г 6 6 .6 5 .4 5 .0 4 .9 4 .8 4 .6в)Е -Со 8 5 .6 4 .3 4 .0 3 .8 3 .7 3 .4о £4) 10 5 .1 3 .9 3 .5 3 .3 3 .2 2 .9ЛЭЁ3 20 4 .4 3 .1 2 .7 2 .5 2 .4 2 .1Z

СО 3. 8 2. 6 2 .2 2 .0 1.9 1.6

ra d io a c t iv e n u c lid e . H o w ev er, m a n y s u b s ta n c e s , e s p e c ia l ly o rg a n ic c o m pounds, la c k su ita b le e le m e n ts . In su ch c a s e s , po w d ers co n ta in in g su ita b le e le m e n ts c a n b e u s e d a s m o d e l s u b s ta n c e s , p ro v id e d th e y c o r r e s p o n d in g ra in s iz e and d e n s ity to th e p ow der to b e s tu d ied . E ven v e ry s m a ll q u a n tit i e s of w a te r - s o lu b le s a l t s c a n b e u s e d f o r th e m ix in g of l iq u id s a s e v e r y s a m p le w ill c o n ta in su c h a la rg e n u m b e r of m o le c u le s th a t th e s ta n d a rd d ev ia tio n o f th e s e i s n e g lig ib le .

T h e p re p a ra t io n of l ig h t-w e ig h t c o n c re te is an ex am p le of an in d u s t r ia l p r o c e s s w h e re th o ro u g h m ix in g of th e co m p o n en ts i s n e c e s s a r y to o b ta in a h ig h -q u a l ity p ro d u c t. T h e m a in c o m p o n en ts o f l ig h t-w e ig h t c o n c re te a r e c e m e n t, san d , a lu m in iu m p o w d er and w a te r . T he m ix in g m u s t be v e r y ra p id so th a t th e r e a c t io n b e tw e en th e a lu m in iu m p o w d er and w a te r , w hich g iv e s th e c h a r a c te r is t i c s t r u c tu re of th e re a d y -m a d e p ro d u c t, m u s t not ta k e p la ce in s id e th e m ix e r . In a Sw edish fa c to ry w hich m a n u fa c tu re s lig h t-w e ig h t conc r e te th e m ix in g ta k e s p la c e in b a tc h e s of about 5 m3. To study th e s h o r te s t t im e fo r su ffic ie n t m ixing, a nu m b er of d if fe ren tly -c o n s tru c te d s t i r r e r s have b ee n te s te d . T he m ix in g of ce m e n t, sand and w a te r , w hich i s th e f i r s t s tep in th e p r e p a ra t io n of th e c o n c re te , i s a lw ay s s ta r t e d so m e m in u te s b e fo re th e add ition of th e a lum in ium pow der, and th e m ix ing tim e fo r th is f i r s t s tep can b e c h o s e n w ith a good m a rg in . In m ix in g c o m p o n e n ts su c h a s c e m e n t and sa n d , w h ich a r e h e a v y in c o m p a r is o n to w a te r , th e r e s u l t i s n o t on ly d ependen t on th e m ix in g t im e bu t, to a la rg e ex ten t, on th e flow p a t te r n in s id e th e m ix e r . F o r good m ix ing r e s u l t s w ith com pounds of v e ry v a r ie d dens i t ie s , s tro n g ax ia l s t r e a m s a r e n e c e s s a ry to allow hom ogenization .

R a d io a c tiv e t r a c e r s h a v e b e e n u se d to s tu d y ±he m ix in g p r o p e r t i e s of so m e su c h m ix e r d e s ig n s [15]. T h e e x p e r im e n ts w e re to s tudy , on th e one hand, th e d is tr ib u tio n of th e a lum in ium pow der, a f te r v a r io u s m ixing perio 'ds, and on th e o th e r , th e d is t r ib u tio n of ce m e n t in th e san d sludge a s a function of m ix in g tim e .

C em ent and a lum in ium pow der, i r r a d ia te d in the Sw edish n u c le a r r e a c to r R l , w e re u se d a s t r a c e r s . W hen a lu m in iu m po w d er i s i r r a d ia te d , A126

i s fo rm e d , bu t th is h a s to o s h o r t a h a l f - l i f e to b e u se d fo r su ch an e x p e r i m e n t. T e c h n ic a l a lu m in iu m p o w d e r i s know n h o w e v e r to c o n ta in s e v e r a l im p u r i t ie s , e . g. m a n g a n e se , w hich, when i r r a d ia te d w ith n e u tro n s , fo rm s


Mn56 w ith a h a l f - l i f e of 2. 6 h. I td e c a y s w ith th e e m is s io n of h ig h ly -e n e rg e tic /3- and y-r a d ia t io n . W hen c e m e n t i s i r r a d ia te d N a24 ( h a l f - l i f e 15.0 h ) and K42 (h a lf - l if e 1 2 . 8 h) a r e fo rm e d , to g e th e r w ith a n u m b e r of s h o r t - l iv e d n u c lid e s such a s Mn56 and Si3i. By im p lem e n tin g th e i r r a d ia t io n one day b e f o re th e e x p e r im e n t th e s h o r t - l iv e d is o to p e s d ec ay a lm o s t c o m p le te ly and r a d ia t io n f ro m th e m ix tu re of N a24 and K42 i s p re d o m in a n t.

In each e x p e r im e n t only one of th e s e m ix ing c o u rse s w as stud ied . T heor e t i c a l ly i t w ould h a v e b ee n p o s s ib le to m ix bo th a c tiv e c e m e n t and a c tiv e a lu m in iu m p o w d e r in th e s a m e e x p e r im e n t b u t t h i s w ould h a v e d e m a n d e d m o r e c o m p lic a te d m e a s u r in g e q u ip m e n t th a n w a s a v a ila b le .

T he fa c to ry w as s itu a te d about 30 km fro m th e r e a c to r , and it w as th u s p o s s ib le to m a k e a n u m b e r of e x p e r im e n ts in one day , e a c h s ta r t in g abou t h a lf an h o u r a f te r th e end of i r r a d ia t io n and b e in g p e r fo rm e d d u r in g i r r a d ia tio n of th e n ex t b a tc h of p o w d er.

T he q u a n titie s i r r a d ia te d w e re 10-20 g fo r each ex p e rim e n t. T he ac tiv e a lu m in iu m pow der w as f i r s t m ixed in to the to ta l quan tity of a lum in ium pow der (1-2 kg). P re -m ix in g of th e i r r a d ia te d c e m e n t in to th e to ta l (about 1 t) w as n o t p o s s ib le but th e p r e - m ix tu r e c o n s is te d of abou t 15 kg.

S am p les w e re ta k en d u rin g th e tap p in g of a m ix e r in to open m o u ld s e v e ry te n th second and th e s a m p le s w e re t r a n s f e r r e d to ca n s w h ere th e conc r e te w as allow ed to so lid ify .

T a b le II sh o w s th e r e s u l t s f ro m t h r e e s e r i e s of e x p e r im e n ts . In th e f i r s t two, m e a s u re m e n ts w e re p e r fo rm e d w ith a G M -coun te r and in th e th i r d w ith a s c in t i l la t io n c o u n te r . In th e f i r s t tw o c a s e s m e a s u r e m e n t w as m a d e c lo s e to th e s u r f a c e of th e s o lid if ie d c o n c r e te , w h ich c o r r e s p o n d e d to an in f in ite ly - th ic k la y e r of h o m o g e n e o u s ly -d is tr ib u te d /3-e m it te r . In th e th i r d c a s e th e c a n s w e re p la ce d on top of th e s c in til la tio n p ro b e so th a t sm a ll u n avo idab le v a r ia t io n s in th e f illin g of th e ca n s w ere a lm o s t co m p le te ly e l im in a te d . In th e l a t t e r c a s e about 40 000 a c tiv e g ra in s co n trib u te d to th e coun tin g r a t e and in th e f i r s t tw o c a s e s on ly abou t 3 000. T h is g iv e s a d e v ia tio n f ro m an uneven n u m b e r of a c tiv e g ra in s of 0. 5 and 1. 8%, re s p e c tiv e ly . F o r th e /З-m e a s u re m e n ts , about 1000 p u ls e s w e re r e c o rd e d fo r each sa m p le and a t l e a s t 20 000 7 -m e a s u re m e n ts .

In th e e x p e r im e n t w ith th e s c in ti l la t io n co u n te r , th e s ta n d a rd d ev ia tio n f ro m th e ra d io a c t iv e d ec ay w as l e s s th a n 1%. B e c a u se of i r r e g u la r i t i e s in th e s a m p le s and c e r ta in v a r ia t io n s in th e m a in s v o ltag e , w hich a ffec ted th e s ta b ili ty of th e m e a su r in g equipm ent, such a low v a r ia n c e w as n e v e r r e c o rd e d . T h is m e a n s th a t th e X 2-test a lw ay s gave s ig n if ic a n tly h ig h e r v a lu e s th a n th o s e e x p e c te d f ro m ra d io a c t iv e d e c a y . I t w as t h e r e f o r e n e c e s s a r y to u s e th e F - t e s t b a s e d on th e c a lc u la te d si fo r a hom ogeneously-m Í3¿ed b a tch . As th is v a lu e w as chosen , th e a v e ra g e d ev ia tio n in th e th r e e c e m e n t-m ix in g s tu d ie s w as 2. 9%. T h is w as b a se d upon 45 m e a s u re m e n ts .

F o r th e GM m e a s u r e m e n ts th e d e v ia tio n c a lc u la te d f ro m th e r a d io a c tiv e d e c a y w a s c a lc u la te d to b e 4 to 7%. A d d itio n s d ep e n d in g on v o lta g e v a r ia t io n s and in h o m o g e n e i tie s in th e n u m b e r of g r a in s m u s t h o t b e c o n s id e re d , a s th e to ta l d e v ia tio n i s r e c e iv e d f ro m -a n a d d itio n of th e s q u a re s of th e c o n tr ib u tin g co m p o n en ts . T h e X '^-test w as th e r e f o r e ap p lied .

T he r e s u l t s of th e th r e e e x p e r im e n ts show n in T ab le I can b e s u m m a r ized a s fo llow s:

TABLE И

DEVIATIONS IN MIXING STUDIES

Labelledcompound

Cem entmixing

(sec)

Aluminiummixing

(sec)

Number of samples

Calculáteddeviation

s(%)

Deviation of method

or Si(%)

S2 /Sjor

sVo*

F 95% Result Comment

Mixer 1

Aluminiumpowder 240 25 13 18.8 5 14.0 1.75 s >o Not homogeneous

240 45 12 12.0 5 5.8 1.79 s > о •*и 240 70 16 9 .3 5 3 .4 1.66 s > о•• 240 70 14 7 .1 5 2 .0 1.77 s > o "» 240 120 12 8 .5 5 2.9 1.79 s > о "

Cem ent 180 60 15 4 .9 4 1.5 1.69 s = о- 240 60 14 5.7 5 1.3 1.70 s = о" 300 60 15 6 .6 4 2 .7 1.69 s > o Not homogeneous

Mixer 2

Aluminiumpowder 240 40 10 4 .7 5 1.0 1.88 s = о

" 240 40 11 6 .2 5 1 .5 1.83 s - a" 240 55 10 5.5 5 1.2 1.88 s = 0- 240 60 13 7.0 7 1.0 1.75 s — о

Cem ent 180 60 12 6 .2 4 2 .4 1.79 s > о Not homogeneous» 240 60 13 5 .6 5 1.3 1.75 s = a•• 300 60 12 4 .5 4 1.3 1.79 s = a

Mixer 3

Aluminiumpowder 240 30 13 10.0 2 .9 12.0 1.98 s > Sj Not homogeneous

" 180 60 15 4 .3 2 .9 2 .2 1.92 S >$1 *Cem ent 90 60 15 2.8 2 .9 1.0 1.92 S = S J

" 150 60 14 2.9 2 .9 1.0 1.95 S = Sj" 195 60 16 3 .0 2 .9 1.0 1.86 S = Sj


T he m ix e r te s te d in th e f i r s t s e r ie s gave b^d m ix in g p ro b ab ly due to the f a c t th a t i t d id n o t p ro d u c e a x ia l s t r e a m s s t r o n g enough to t r a n s p o r t th e a lu m in iu m p o w d er aw ay f ro m th e s u r fa c e n o r p re v e n t s e d im e n ta tio n of th e ce m e n t. T he seco n d m ix e r show ed m o s t fav o u ra b le m ix in g p r o p e r t ie s , bo th w ith th e c e m e n t and th e a lu m in iu m p o w d er. S u ffic ien t m ix in g i s p ro b a b ly r e a c h e d in 40 s e c f o r th e a lu m in iu m p o w d e r and in ab o u t 200 s e c f o r th e c e m e n t. T h e th i r d m ix e r p ro d u ce d good h o m o g e n iza tio n of th e ce m e n t, b u t m ix in g f o r m o r e th a n 60 s e c i s n e c e s s a r y f o r th e c o m p le te m ix in g o f th e a lu m in iu m p o w d er to ta k e p la c e . It i s b e lie v e d th a t an in c r e a s e in s t i r r in g sp e e d cou ld im p ro v e th e m ix in g p r o p e r t ie s .

T h is m e th o d i s now g e n e r a l ly a p p lied in th e d e v e lo p m e n t of m o r e e f fe c tiv e m ix in g a p p a r a tu s .

R E F E R E N C E S

[1J HULL, D . E . , FRIES, B. A . , TEWKSBURY. J. G. and KERNS, G. H ., "M ixing in surge Tanks and S tills” , Nucleonics 14 5 (1956) 51.

[2] HULL, D .E .. FRIES, B. A . , TEWKSBURY, J. G. and KERNS, G. H . , "Isotopes solve m ixing Problem s", Nucleonics 14 5 (1956) 50.

[3] ANDERS, O. U . , "A cce le ra to r-m ad e T racer solves a m ixing Problem ", N ucleonics 18 12 (1960) 77.[4] LIPLAUK, L L. and BOLITER, E. P . , "Radiom etric M ethod of determ ining the Degree of coal M ixing",

Industrial Laboratory (Zavod. Lab) 25 (1959) 1127.[5] BEEN, U. and SAELAND, E . , "Some industrial Uses of Radioisotopes in Norway", Proc. 1st UN Int. Conf.

PUAE (1955) 170.[6] ERWALL, L. G. and UUNGGREN, K ., "Recent Uses of Radioisotopes in technological Research and Control

in Sweden", Proc. 2nd UN Int. Conf. PUAE 19 (1958) 3.[7] LUOTO, Ù. A. and ROTKIRCH, E. G , , "Tracer Techniques in Finnish Industry", Proc. 2nd UN Int. Conf.

PUAE 19 (1958) 28.[8] JEFFERSON, S. and WILDBLOOD, A .M ., "Testing feed m ixing Efficiency", The A gricultural M erchant

(Sep. , 1956).[9] "Radioisotopes N ewsletter", A tom ic Energy 3 3 (1960) 11.

[10] HOFFMAN, A. М ., "R adioactive trace r Techniques in solid p ropellan t M ixing", Ind. Eng. C hem . 52 (1960) 781.

[11] OVERMAN, R .T . and CLARK, H. M . , "Radioisotope T echn iques", M cG raw -H ill, New York (1960) 98-130.

[12] FRIEDLANDER, G. and KENNEDY, J. W ., "N uclear and R adiochem istry", W iley and Sons, New York (1955) 252-70.

[13] DIXON, W. J. and MASSEY, F. J . , J r . , "Introduction to s ta tis tica l Analysis", 2nd e d . , M cGraw-Hill, New York (1957) 1Q2-83.

[14] MORONEY, M .J . , "Facts from Figures" Penguin, London (1956) 82-119.[15] FORSBERG, H. G. and BJERLE, L . , "K ontroll av pulverblandning m ed rad ioak tiva spâram nen", T ekn.

Tidskrift 92 (1962) 717.

D I S C U S S I O N

E . SOMER: T he s ta n d a rd d ev ia tio n m en tio n e d in y o u r p a p e r d ep en d sa ls o upon sa m p le s iz e . In y o u r r a d io a c t iv i ty m e a s u re m e n ts , s a m p le s iz e d epends upon g e o m e try and upon th e e n e rg y of th e ra d ia tio n em itte d by y o u r t r a c e r . A s you a r e u s in g n a tu r a l m a te r i a l a c t iv a te d in th e r e a c to r , th e r e w ill b e d if fé re n t ra d io iso to p e s w ith d if fe re n t e n e rg ie s and h a l f - l iv e s so th a t th e " s a m p le s iz e " w ill ch an g e d u r in g y o u r m e a s u r e m e n ts . H ave you ta k e n th is in to acco u n t?

268 I. BJERLE

In a n o th e r p a p e r to be p re s e n te d a t th is S em in a r* we d e s c r ib e th e u se of g o ld -198 fo r la b e ll in g th e m a te r ia ls m en tio n ed in y o u r p a p e r . By u s in g a r a d io c h e m ic a l ly - p u r e t r a c e r th e ab o v e p r o b le m c a n b e a v o id e d , an d th e s a m e " s a m p le s iz e " e n s u re d fo r a ll th e d if fe re n t m a te r ia l s in v e s tig a te d in a p r o c e s s .

H. G. FO R SB ER G : S ince th e n u m b e r of c o n tr ib u tin g g r a in s cou ld no tb e d e te rm in e d e x a c tly , th is e ffe c t w as no t ta k e n in to acco u n t. H ow ever, i t w a s p ro b a b ly n o t s e r io u s , a s in th e c a s e of a lu m in iu m a t l e a s t 95% of th e r a d ia t io n e m itte d in th e m e a s u r in g p e r io d w a s f ro m Mn56. In th e c a s e of i r r a d i a t e d c e m e n t th e r a t i o K 42 to Na24 d e c r e a s e s w ith t im e , b u t i f th e m e a s u re m e n ts ta k e p la c e w ith in a p e r io d of 1 - 2 h th e e ffec t i s m in im iz e d .

K. FRÜHAU F: I shou ld lik e to m en tion an exam ple show ing the ex ten tto w hich p a r t ic le s ta t i s t i c s a ffec t the o v e ra ll e r r o r . In a sand m ig ra tio n e x p e r im e n t s ta r t in g w ith 100 k g of la b e l le d sa n d , w h e re c o u n tin g s t a t i s t i c s in tro d u c e d an e r r o r of 1%, th e to ta l e r r o r w as a s h ig h a s 7% ow ing to th e s m a l l n u m b e r of la b e l le d g r a in s in th e s a m p le d raw n .

P . C . A E B E R S O LD (C h a irm a n ): W hat i s th e a n s w e r to th i s th e n , tou s e m o r e san d ?

H. G. FO R SB ER G : If you can .K. FR U H A U F: O r n o t to co u n t so m a n y coun ts.. In th a t w ay you can

sa v e t im e .H. G. FORSBERG: Y es. We can save tim e by not tak ing too m any counts

if we have a su ff ic ie n tly l im ite d n u m b e r of g ra in s . T he to ta l s ta n d a rd d ev ia tio n w ill c o n s is t of sq u a re d d ev ia tio n s f ro m th e v a r io u s c o n tr ib u tio n s , w ith th e r e s u l t th a t one l a r g e d is p e r s io n w ill b e r e s p o n s ib le f o r a lm o s t a l l th e r e s u l t in g s ta n d a rd d e v ia tio n .

* B.R. Petersen, "Radioactive surface labelling of powdered m aterials by means of gold-198", These proceedings.

RADIOACTIVE SURFACE LABELLING OF POWDERED MATERIALS BY MEANS OF GOLD-198

B.R. PETERSENDANISH ISOTOPE CENTRE, ACADEMY OF TECHNICAL SCIENCES,

COPENHAGEN, DENMARK


RADIOACTIVE SURFACE LABELLING OF POWDERED MATERIALS BY MEANS OF GOLD-198. T he in vestigation o f m a te ria l transport is often advantageously performed using radioactive tracers. Exploration by non-iso topic labe lling is often necessary because o f lack of conveniently ac tiv a ted isotopes in the m a te ria l under investigation.

The principle of the m ethod described in the paper is the reduction of gold from a solution of gold-198 on th e surface o f the m a te ria l to be lab e lled , this m a te ria l having been p re -trea ted w ith stannous chloride. This m ethod has been em ployed for the labe lling of q u ic k -lim e , cem ent and o ther powdered m ateria ls, but a m ore general app lication for labelling seems possible.

MARQUAGE RADIOACTIF SUPERFICIEL DE MATIERES PULVÉRULENTES AU MOYEN DE L’OR-198. Pour é tud ier le transport des m atières, on a souvent in térêt â em ployer des radioindicateurs. Dans b ien des cas, i l fau t recourir a u m arquage non isotopique parce qu 'on ne dispose pas, pour la m a tiè re à l 'é tu d e , d 'iso topes radioactifs appropriés.

Le principe de la .m éthode d écrite dans le m ém oire consiste â réduire l 'o r d 'une solution d 'o r - 198 â l a surface de la m a tiè re â m arquer, ce tte m a tiè re ayant é té p réalab lem ent tra itée au chlorure stanneux. C ette m éthode a été" u tilisée pour m arquer de la chaux v ive , du c im en t e t d 'au tres m atières pulvérulentes, m ais e l le sem ble susceptible d ’une app lication plus générale.

РАДИОАКТИВНОЕ МЕЧЕНИЕ ПОВЕРХНОСТЕЙ ПОРОШКОВЫХ МАТЕРИАЛОВ С ПОМОЩЬЮ ЗОЛОТА-198. Исследование переноса материала часто с успехом осуществляется с помощью радиоактивных индикаторов. Исследование с помощью неизотопного мечения'часто является необходимым из-за отсутствия активированных обычным способом изотопов в исследуемом материале. В основе метода» описанного в докладе» лежит восстановление золота из раствора золота-198 на поверхности материала, подлежащего мечеяию» который -предварительно обрабатывается двухлористым оловом. Этот метод используется для мечения негашеной извести» цемента и других порошковых материалов» но представляется также возможным его более широкое использование.

MARCACION RADIACTIVA DE LA SUPERFICIE DE MATERIALES PULVERULENTOS MEDIANTE ORO-198. El em p leo de indicadores radiactivos fa c ilita con frecuencia e l estudio d e l transporte de m ateria les, pero en muchos casos es preciso em plear indicadores de otra clase por carecer de radioisótopos adecuadamente activados del m ateria l que se estudia.

El princip io d e l m étodo descrito en la m em oria consiste en reducir e l oro de una solución de o ro -198 en la superfic ie d e l m a te ria l a m a rc a r después d e haberlo tra tad o con clo ruro estannoso. El m é to d o se ha e m p lead o para m a rca r c a l v iv a , cem en to y otros m a te ria le s en polvo , pero a l p a rece r, puede destinarse tam b ién a ap licac iones de c a rá c te r m as g eneral.

1. IN T R O D U C T IO N

Investigation of tran sp o rt of m a te r ia l i s often perform ed advantageously by rad io a c tiv e t r a c e r s . The m ethod g e n e ra lly p r e fe r r e d i s iso to p ic la b e lling, which h ere im p lie s e ith er activation o f the m ate r ia l it se lf , o r syn th esis with an ap p ro p ria te rad io ac tiv e com ponent. T h is p rocedu re i s often not p o ss ib le , fo r exam ple , when the m a te r ia l in question d o es not contain elem ents

269

270 В. R. PETERSEN

w hich can be re a d ily ac tiv a te d to p roduce ra d io iso to p e s having su itab le r a d i a tio n and h a l f - l if e . A n o th er p o s s ib ili ty is to u se n o n -iso to p ic lab e llin g , th a t i s , lab e llin g w ith rad io a c tiv e iso to p es of e lem e n ts o th e r than those c o n s titu tin g th e su b s ta n c e to be t r a c e d . Som e a d v a n ta g e s and d is a d v a n ta g e s of th e tw o m e th o d s a r e l i s te d in T a b le 1.

In 1957 th e D a n is h Iso to p e C e n tre d e v e lo p e d a s im p le m e th o d w h ich , to a c e r ta in ex ten t, s e e m s to be ap p lica b le g e n e ra lly . The m ethod h a s been u s e d on s e v e r a l o c c a s io n s d u r in g th e p a s t f iv e y e a r s w ith good r e s u l t s . It c o n s is t s of s u r f a c e - la b e l l in g of th e m a te r i a l w ith A u 198.

2. L A B E L L IN G W ITH Au^S

T he d ec ay d a ta of Aui98 (4 1 1 k eV g am m a ph o to n s; h a lf - life 2. 69 d) m ake i t a u se fu l iso to p e fo r f u l l - s c a le in v e s tig a tio n of m ix ing and flow p r o c e s s e s w ith r e s p e c t bo th to d e te c tio n and h e a lth p h y s ic s c o n s id e ra t io n s .

L a b e llin g i s p e r f o rm e d by re d u c tio n of go ld f ro m a so lu tio n o f r a d io a c tiv e gold c h lo r id e onto th e s u r fa c e of the m a te r ia l , w hich i s f i r s t t r e a te d w ith a so lu tion of s tannous ch lo rid e . The p rin c ip le of the labelling p ro ce d u re i s the fo llow ing:

2. 1. P R IN C IP L E FOR SURFACE LABELLING OF FINELY-D IVIDED M ATERIAL WITH Auisa

1. N o n -ra d io a c tiv e w ork1 .1 . The m a te r ia l is s lu r r ie d (in w a te r o r e th e r).1 . 2. A so lu tio n of s tan n o u s c h lo rid e (in w a te r o r e th e r) is added du ring

s t i r r i n g .1. 3. The s lu r r y i s le f t fo r five m in u tes .1 . 4. F i l te r in g , d ecan tin g o r ce n tr ifu g in g .1. 5. W a sh in g fo u r t im e s w ith w a te r o r e th e r f o r r e m o v a l o f e x c e s s

s ta n n o u s c h lo r id e .2 . R a d io a c tiv e w o rk2. 1. G o ld - 198 c h lo r id e s o lu t io n (in w a te r o r e th e r ) i s ad d e d w h ile

s t i r r i n g to a s l u r r y of th e t r e a te d m a te r ia l . T he go ld i s re d u c e d q u a n tita tiv e ly on th e s u r fa c e of th e m a te r ia l .

2 . 2 . D ec an tin g .2 . 3 . D ry in g .

T he p r e l im in a r y t r e a tm e n t i s p e r fo rm e d w ithout ra d io a c tiv e m a te r ia ls and ca n th e r e fo r e be c a r r i e d out a s n o r m a l la b o ra to ry w o rk . T he m a te r ia l i s f i r s t b ro u g h t in to su sp e n s io n . S u b stan c es in so lu b le in w a te r a r e s lu r r ie d in w a te r . S u b s ta n c e s w h ich a r e s o lu b le in w a te r o r r e a c t w ith w a te r a r e s lu r r i e d in e th e r . T he fo llo w in g t r e a tm e n t i s c a r r i e d ou t a c c o rd in g to th e above s c h e m e , th e so lv e n t f o r s ta n n o u s c h lo r id e b e in g w a te r o r e th e r a c c o rd in g to th e s u s p e n s io n m e d iu m c h o se n .

T he so lu b i l i ty o f go ld c h lo r id e in e th e r i s p ro m o te d by th e ad d itio n of a l i t t l e a b s o lu te a lc o h o l. F in e ly p u lv e r iz e d g o ld c h lo r id e i s u s e d f o r th e a c t iv a tio n . T h e re d u c t io n o f th e go ld ta k e s on ly a few m in u te s .

I f th e p r e - t r e a t m e n t i s m ad e c o r r e c t ly a q u a n tita tiv e re d u c tio n on th e s u r fa c e i s o b ta in ed .

T A B L E I

L A B E L L IN G M E T H O D S

A dvantages D isadvantages

1. Iso topic lab e llin g C hem ica l and physical transport processes c an b e investigated

Radiation is proportional to the am ount o f substance

1 .1 . A c tiva tion o f th e substance The na tu ra l substance

No preparations

Unw anted a c tiv itie s

R adiation dam ag e

1 .2 . Synthesis No unw anted ac tiv itie s Not th e n a tu ra l substance

P reparation

2. N on-iso top ic lab e llin g Indépendance o f the o ccu rrence of e lem en ts th a t can be a c tiv a ted . C hoice o f an e sp ec ia lly ap p ro p ria te isotope possible

Only physica l transport processes can be followed

2. 1. H om ogeneous lab e llin g R adiation proportional to the am ount of m a tte r

O ften unusable for solids

2 .2 . Inhom ogeneous lab e llin g , e . g. su rface lab e llin g

O ften usable w here o ther m ethods fa il

R adiation not proportional to the am oun t o f m a tte r but to su rface. T he ac tiv ity can be worn o ff

LA

BE

LL

ING

OF

PO

WD

ER

ED

M

AT

ER

IAL

S

BY G

OL

D-19

8

27

1

272 В. R. PETERSEN

A s an exam ple of application to powdered m a te r ia ls , it can be mentioned that in in v e stig a tio n s in the cem ent in du stry , w here the lab e lled su b sta n ce s w e re cem en t, q u ick lim e and a lu m in iu m pow der, 0. 2 5 -g am o u n ts o f go ld ch lo rid e , with a c t iv it ie s ran ging fro m 125 - 250m c, w ere u sed fo r the labellin g o f 2 5 0 - 3000 g o f m a te r ia l. T h ese am ounts could be tra c e d when they w ere m ixed with up to 1001 o f m a te r ia l. The ad so rp tio n o f gold onto the su r fa c e o f the m a t e r ia l s h a s , in th e se a p p lic a tio n s , been q u an tita tiv e . In w ash in g and shaking ex p erim en ts only l%o o f the app lied am ount of gold could be r e m oved.

In the lab e llin g of quicklim e the above sch em e i s followed s tr ic t ly using e th e r a s a m edium . F o r cem en t a b e tte r r e su lt i s obtained by u sin g w ater d u rin g the p re lim in a r y tre a tm e n t . Im m ed ia te ly a f te r th is , se tt in g o f the cem en t i s p rev en ted b y w ash in g with a b so lu te a lco h o l and e th e r .

F o r a lum in ium pow der the trea tm en t w as c a r r ie d out in w ater and the w etting o f the a lum in ium w as p rom oted u sin g the su r fa c e - a c t iv e su b stan ce L is sa p o n N. The s lu r r y w as c a re fu lly heated until hydrogen w as l ib e ra te d . H ydrogen lib e ra tio n w as stopped by qu ick fi lte r in g and w ashing with ether, which w as u se d durin g the r e s t o f the trea tm en t.

The ap p aratu s u sed in the p reparation i s very sim ple (F ig . 1). The rad io a c tiv e so lu tio n i s p re p a re d in the f l a s k shown on the le ft in the f ig u re , the gold ch lo rid e being added to the so lven t by m ean s o f rem ote handling ton gs. The connection to the f la sk i s a ru bb er tube, allow ing the f la sk to be shaken.

Fig. 1

Apparatus for lab e llin g w ith gold-198

A fte r d isso lu tio n , the gold ch lo rid e i s pum ped by m ean s o f the ru b b er b a ll, in to the bo ttle sh ie ld ed by le a d . F r o m h e re by m e a n s o f the b u rette , it i s quan titatively tr a n s fe r r e d to the v e s s e l containing the p re -tre a te d m a t e r i a l w hile s t i r r in g . T he b u re tte i s f i lle d by m e an s o f the ru b b e r b a l l to th e r igh t.

Quite recen tly we t r ie d th is m ethod fo r lab e llin g straw in in v estigatin g a p r o c e s s in the s tra w c e llu lo se in du stry .

LABELLING OF POWDERED MATERIALS BY GOLD-198 273

P r e l im in a r y in v e s t ig a t io n s sh o w ed th a t a p p l ic a tio n o f th e m e th o d d e s c r ib e d to u n tr e a te d s tr a w d id not g ive s a t is f a c to r y a d so rp tio n o f th e gold. In o u r s p e c if ic p ro b le m , t r a n s p o r t o f th e s t r a w ta k e s p la c e in a 20% h o t so d iu m h y d ro x id e so lu tio n , w h ere a c o n s id e ra b le am oun t of m a te r ia l i s e x t r a c te d f ro m th e s tra w . We th e re fo r e t r e a te d th e s t r a w w ith a 20% so lu tio n o f so d iu m h y d ro x id e a t 100°C fo r h a lf an h o u r an d a f te rw a r d s w a sh e d an d d r ie d i t . E th e r e x t ra c tio n of th e s t r a w th e n to o k p la c e . T he s t r a w w as n ex t t r e a te d fo r a p p ro x im a te ly 1 h, f i r s t w ith a so lu tio n of s tan n o u s c h lo rid e in e th e r and th e n w ith a so lu tio n of go ld c h lo r id e in e th e r . By th is m o d if ic a tio n we o b ta in ed f i rm la b e ll in g . O ur p r e l im in a ry r e s u l t s in d ic a te th a t an up take of 0. 2 m g gold p e r g ra m of s tr a w can be ob ta ined w ith 20% u tiliz a tio n o f th e g o ld . W e h av e h o w e v e r good h ope o f im p ro v in g th e u p ta k e . In th e a g g re s s iv e t r a n s p o r t m ed ium u sed , le s s th a n 5 % of th e a c tiv ity i s rem o v ed .

T he la b e llin g m ethod d e s c r ib e d a p p e a r s to have m any p o te n tia l a p p lic a tio n s and i t i s b e liev e d to be e s p e c ia lly su ita b le fo r la b e llin g te x tile f ib re s , f i l l e r s in th e ru b b e r in d u s t ry and c h ip s of s u g a r b e e ts in th e s u g a r in d u s try .

D I S C U S S I O N

P . C . A EBERSO LD (C h a irm an ): A s D r. P e te r s e n p o in ts ou t, g o ld - 198 i s a v e r y e a sy iso to p e to p ro d u c e and is v e r y e a sy to hand le f ro m a h e a lth - p h y s ic s s tandpo in t; i t i s a lso qu ite v e r s a t i le and ea sy to m e a su re . It i s in te r e s tin g to h e a r o f i t s u se fo r la b e llin g su ch th in g s a s f ib re s , f i l l e r s e t c . , a s w e ll a s p o w d ers .

J . W ATT: I w ould ju s t lik e to m en tio n th a t we have u se d th e tech n iq u e d e s c r ib e d by D r . P e te r s e n f o r la b e ll in g s i l t and f ly - a s h and found i t v e r y su c c e s s fu l . H ow ever, in la b e llin g c e r ta in k inds of c o a r s e sand we have had no s u c c e s s a t a ll, and we have had to adopt a c o m p le te ly d if fe re n t tech n iq u e ( B ra s h e a r p ro c e s s ) , in w hich in a c tiv e s i lv e r w as a b so rb e d onto th e s u r fa c e o f th e san d and th e n p la ted w ith Au198.

В. R . P E T E R S E N : W e have n o t t r i e d th a t; f o r san d we u s e o th e r i s o to p e s w ith lo n g e r h a l f - l iv e s .

P . C . AEBERSOLD: In M r. W att’s e x p e r im e n ts w ith c o a rs e san d s, why w as the s i lv e r ad so rb e d m o re e a s ily them gold?

J . WATT: Not being a ch e m is t, I do not know. I am quite s u re people at hom e would know.

G. COURTOIS: Could you g ive u s a l i t t le m o re in fo rm a tio n abou t y o u r w ash ing and shak ing m ethods, i . e . the d u ra tio n and freq u en cy of the shaking?

B . R . P ET E R S E N : I canno t g ive you any d e ta i ls about th is m ethod . F o r in d u s t r ia l a p p l ic a tio n s i t i s o ften n e c e s s a r y to find a m e th o d a s q u ic k ly a s p o s s ib le an d if i t s e e m s to w o rk s a t i s f a c to r i ly i t i s ad o p te d . W e h a v e n o t m a d e a s c ie n t if ic in v e s tig a tio n of th is p ro b le m ; we h av e done w ash in g e x p e r im e n ts an d w h a t w e c a l l e x t r a c t io n e x p e r im e n ts , b u t th e y w e r e q u ite s im p le .

G . COURTOIS: H ave you c a r r i e d out any e x p e r im e n ts to show th a t th e a c tiv ity w as p ro p o r tio n a l to th e g ra in s u r fa c e a re a ? In p a r t ic u la r , have you done th is fo r fin e g r a in - s iz e s ?

B . R . P E T E R S E N : N o. W e hav.e n o t m a d e an y s u c h e x p e r im e n ts .

274 В. R. PETERSEN

P , С . A EBERSO LD : But, if I u n d e rs ta n d c o r r e c t ly , you found th a t, fo r a l l p r a c t i c a l p u r p o s e s , th e g o ld s ta y s on th e p a r t i c l e s v e r y f i r m ly ?

B . R . P E T E R S E N : Y e s , th a t i s o u r e x p e r ie n c e .C. TAYLOR: I would ju s t lik e to m en tion th a t I have used su rfa c e la b e l

lin g w ith gold fo r a t r a c e r e x p e r im e n t in th e R iv e r Hooghly a t C a lcu tta . The san d to be la b e lle d co n ta in ed about 45% q u a r tz , 50% o r th o c la se and 5% m ica , th e p a r t ic le s iz e being about 100/i . We found th a t Au198 d ep o s ited f ro m goldc h lo r id e so lu tio n a t ta c h e d i t s e l f in eq u a l p ro p o rtio n s to th e m ic a and to the o r th o c la s e , v e r y l i t t le indeed going in to th e q u a r tz . If M r. W att had to d e a l w ith a q u a r tz s a n d w e w ould e x p e c t so m e d if f ic u lty in g e t t in g th e g o ld to s t ic k .

In o u r e x p e r im e n t w e w e re w o r r ie d ab o u t th e h ig h p r o p o r t io n o f th e a c t iv i ty a b s o rb e d by th e m ic a , a s i t w as in f la k e fo rm and i t s m o v e m e n ts w ould p ro b a b ly n o t be r e p r e s e n ta t iv e of th e bu lk of th e sa n d . We th e re fo r e u se d a f lo ta tio n ta b le to p r e p a r e a 10-kg sa m p le of san d w ith re d u c e d m ic a co n ten t. W hen th is w as la b e lle d , a lm o s t a l l th e a c tiv ity w ent in to the o r th o c la s e . The ta n k we u se d fo r th e p u rp o se w as in th e r iv e r , and the sand w as a c tu a lly m ix ed in th e r i v e r .

T he m e th o d of la b e ll in g w as th a t d e s c r ib e d by th e U nited S ta te s g ro u p w h ich h a s c a r r i e d ou t t r a c e r e x p e r im e n ts in San F r a n c is c o H a rb o u r . If I re m e m b e r c o r re c tly , we found th a t the stannous ch lo rid e s te p w as not n e c e s s a r y w ith o u r sand : a ttac h m e n t w as ra p id and se c u re w ithout it.

J . W A TT: We a r e a w a re th a t q u ite a few p eo p le have in fa c t la b e lle d sa n d w ith g o ld . P ro b a b ly o u r s a n d i s a m u c h f in e r v a r i e ty th a n y o u r s .

TEST METHOD FOR DETERMINATION OF CARBON PAPER TRANSFER CHARACTERISTICS*

C .C . THOMAS, JR. * * AND R. F. HORAN QUANTUM IN C ., WALLINGFORD, CONN.

AND D. M. HART MOORE BUSINESS FORMS INC. , NIAGARA FALLS, N. Y. ,



TEST METHOD FOR DETERMINATION OF CARBON PAPER TRANSFER CHARACTERISTICS. One type

of card in large-scale use in the data processing field has inform ation im printed on the card with carbon paper. The transfer of a portion of this im age to the data processing equipm ent (such as card sorters) can cause m alfunction of the m achines. In addition , re-transfer to the cards can result in loss of leg ib ility . A test m ethod for the evaluation o f carbon-paper ink form ulations th a t would yield da ta on transfer characteristics w ith a m inim um ot test samples under dynam ic conditions was desired. A radiotracer test method has been developed which adequately fills the test requirements.

The method consists, essentially, of activation of the carbon paper, imprinting the tab cards, and processing the cards through a standard card sorter. The d e tec tio n system consists o f a shielded GM tube m ounted over one w heel of the card sorter, a counting ra te m eter with a fast response tim e , a high speed strip chart recorder and associated power supplies.

The carbon-paper samples were irradiated in a 1 MW pool-type research reactor in a flux of 1 xlO 13 n /cm 2s for 2 h. G am m a-ray spectroscopy and h a lf - l iiè determ inations ind ica ted tha t th e m ajor ac tiv itie s produced included sodium -24, m anganese-56and ch lo rine-38. The test runs were generally m ade within 3 h after completion, of the irradiation.

The recorder traces of each test run were subjected to polynomial curve fitting techniques using a dig ital computer. The derived equation for each run was then converted to weight data based upon the specific activity of a known weight of the carbon-paper ink. The standards were prepared by solvent extraction of the ink from an irradiated sam ple of the carbon paper.

The test m ethod can be used to determ ine the re la tive transfer characteristics of carbon-paper inks to the wheels of a card sorter. The desired data can be obtained with 100 cards and a m axim um card sorter run of 30 s. The method replaces a former procedure which required 10 000 card runs and did not yield quantitative weight transfer data.

The test method is described in detail and the results of experim ental runs on four carbon ink formulations are presented.

MÉTHODE DE VÉRIFICATION TOUR DÉTERMINER LES CARACTÉRISTIQUES DU TRANSFERT DU PAPIER CARBONE. Sur certaines cartes couramment utilisées pour le traitem ent des données, l'inform ation est imprimée â l 'a id e de papier carbone. Le transfert d ’une partie de l'im pression â certains élém ents du m até rie l de tra ite m en t des données (trieuses de cartes, par exem ple) peut en traîner un m auvais fonctionnem ent des m achines. De plus, un retour de ce carbone aux cartes risque d 'en diminuer la lisibilité. Il é ta it donc nécessaire dem ettre au point une m éthode de vérification qui perm ettra it de déterm iner les caractéristiques du transfert á l 'a id e d 'u n m inim um d 'échan tillons tém oins, dans des conditions dynam iques. On a m is au point une m éthode de vérification au m oyen de radio indicateurs, qui répond aux conditions requises.

C ette m éthode consiste essentiellem ent â activer le papier carbone, â im prim er les cartes e t ¿ le s fa ire passer par une trieuse de type courant. Le système de détection comprend un tube GM blindé, monté au-dessus

* This work was carried out using the facilities of the Western New York N uclearR esearchC enteratthe State University of New York a t Buffalo.

Presently a t the Western New York N uclear Research Center.

275

276 С . C . THOMAS Jr. et a l.

d 'un rouleau de la trieuse, un intégrateur â temps de réponse rapide, un appareil enregistreur sut bande â grande vitesse e t l'a lim en tation électrique nécessaire.

Les échantillons de pap ier carbone ont é té irradiés dans un réacteu r de recherche du type piscine, de 1 MW, à 1 .1013 n /cm 2 . s pendant deux heures. La spectroscopie gam m a e t les mesures de périodeont indiqué que les principaux élém ents radioactifs produits é ta ien t le sodium -24, le m anganêse '56 e t le chlore-38. Les essais a v a ien t généralem ent lieu dans les trois heures qui suivaient la fin de l 'irrad ia tion .

On a appliqué aux enregistrem ents pris au cours de chaque passage les m éthodes d 'a ju s tem en t d 'une fonction aux observations, en utilisant une calculatrice numérique.On a ensuite converti les résultats de l ’équation obtenue pour chaque passage en données correspondant au poids, basées sur l'ac tiv itéspécifique d 'un poids connu d 'encre de papier carbone. Les étalons ont é té préparés par extraction par solvant de l'encre d ’un échantillon irradié de papier carbone.

La m éthode peut être utilisée pour déterm iner les caractéristiques du transfert re la tif des encres de papier carbone aux rouleaux d 'u n e trieuse de cartes. Les données voulues peuvent ê tre obtenues avec 100 cartes e t une durée de passage m axim um dans la trieuse de 30 s. C ette méthode rem place une technique plus ancienne

qui nécessitait 10 000 passages de cartes e t ne perm ettrait pas d 'obtenir sur le transfert des données quantitatives en poids.

Les auteurs décrivent en dé ta il la méthode e t donnent les résultats d ’expériences faites avec quatre encres différentes.

ЭКСПЕРИМЕНТАЛЬНЫЙ МЕТОД ОПРЕДЕЛЕНИЯ ПЕРЕНОСА ХАРАКТЕРИСТИК С ПОМОЩЬЮ КОГМРОВАЛЬНОЙ БУМАГИ. Карточка с копировальной бумагой, на которую наносится информация, широко используется при обработке 'Данных. Перенос части отпечаток в устройство для обработки данных ( такого,как сортировщики карточек) мохет вызвать неполадки в работе машин. Кроме того , обратный перенос на карточки мохет привести к потере четкости. Требовался экспериментальный метод оценки формулировок, нанесенных аа копировальную бумагу, который представлял бы данные по характеристике переноса при минимуме испытательных образцов в динамических условиях. Разработан радиоиндикаторный экспериментальный метод, который в достаточной степени отвечает требованиям опыта.

Этот метод состоит в основном в активации копировальной бумаги, нанесенной ка карточки, и в пропускании карточек через стандартное сортирующее устройство. Детектирование осуществляется с помощью экранированного счетчика Гейгера-Мюллера, смонтированного на колесе сортировщика карточек, и измерителя скорости счета с быстрым временем срабатывания, скоростного самописца со съемной бумагой и источников электропитания.

Образцы копировальной бумаги облучались в исследовательском реакторе бассейнового типа мощностью 1 мгвт ори 1 *Ю13к/см2 ■сек в течение 2 час. Гамма-спектроскопия и определение периода полураспада показали, что большая часть полученных радиоизотопов включала натрий-24, марганец-56 и хлор-38. Испытательные пробеги, как правило, проводились в течение трех часов после окончания облучения.

Регистрационные записи каждого испытательного пробега подвергались обработке методом подгонки кривой полинома при использовании счетнорешающего устройства. Уравнение, полученное для каждого п робега, переводилось затем в весовые данные, основанные на удельной активности копировальной бумаги известного веса. Стандарты готовились с помощью селективной экстракции черного слоя из облученного образца копировальной бумаги.

Экспериментальный метод мохет использоваться при определении сравнительных характеристик переноса черного слоя копировальной бумаги на колеса сортировщика карточек. Необходимая информация мохет быть получена на 100 карточках при максимальном пробеге сортировщика карточек 30 сек. Этот метод заменяет предыдущий, требовавший 10 ООО пробегов карточек и не дававший количественных ве- сош х данных переноса.

Д ается1подробное описание вышеуказанного метода, представляются результаты экспериментальных пробегов на четырех копировальных листах.

MÉTODO DE ENSAYO PARA DETERMINAR LAS CARACTERISTICAS DE TRANSFERENCIA DEL PAPEL CARBON. En algunos tipos de fichas corrientemente utilizados en e l análisis de datos, la información se imprime con ayuda de papel carbón. La transferencia de parte de la impresión a las máquinas para e l análisis de datos (por e jem plo , las clasificadoras de fichas) puede afectar e l funcionamiento de las máquinas. Además, e l retomo d e ese carbono a las fichas puede dism inuir la leg ib ilidad .E ra deseable encontrar un m étodo que perm itiera

DETERMINATION OF CARBON PAPER TRANSFER CHARACTERISTICS 277

determ inar las características de transferencia con un m ínim o de m uestras testigo en condiciones dinám icas. Se ha perfeccionado un m étodo de ensayo con indicadores radiactivos que cum ple sa tisfac to riam en te estos requisitos.

El m étodo consiste en activar e l papel carbón, im prim ir las fichas y hacerlas pasar por una clasificadora co m en te . El sistema de detección está consitituido por un tubo GM blindado que se monta en una rueda de la c la sificado ra , un in tegrador de respuesta ráp ida , un registrador de c in ta de a l ta ve loc idad y las fuentes de a lim en tac ió n necesarias.

Las m uestras de papel carbón fueron irradiadas durante dos horas en un reacto r de investigación tip o piscina de 1 MW, con un flujo de 1.1013 n /c m 2s. Por espectroscopia gam m a y determ inación de los períodos, se comprobó que los principales radioisótopos formados eran e l sodio-24, e l m anganeso-56 y e l cloro-38. Los ensayos se efectuaron generalm ente en las 3 h que siguieron a la irradiación.

Los diagramas del registrador fueron sometidos a métodos polinómicos de ajuste de curvas em pleando una calculadora num érica. A partir de la ecuación obtenida para cada ensayo, se calcularon los pesos correspondientes basados en la activ idad específica de una cantidad conocida de tin ta . Las muestras se prepararon extrayendo con disolventes la tinta de una muestra de papel carbón irradiado.

Este m étodo de ensayo perm ite de te rm inar las características de la transferencia de las diversas tintas a las ruedas de la c lasificado ra . Los datos requeridos pueden obtenerse con 100 fichas haciendo funcionar la c lasificadora durante 30 s. El m étodo sustituye a otro an terio r que em pleaba 10 000 fichas y no perm itía obtener datos cuantitativos acerca de la cantidad de carbono transferida.

La m em oria describe d e ta llad am en te e l m étodo y da los resultados de los experim entos realizados con cuatro tintas de com posiciones d iferentes.

1. INTRODUCTION

O ne ty p e of c a r d in l a r g e - s c a l e u s e in th e d a t a - p r o c e s s in g f ie ld h a s in fo rm a tio n im p r in te d on th e c a r d w ith c a rb o n p a p e r . T h e t r a n s f e r o f a p o rtio n of th is im age to the d a ta -p ro c e s s in g equ ipm ent (such a s c a rd s o r te r s ) can ca u se m a lfu n ctio n of th e m a c h in e s . In add ition , r e - t r a n s f e r to the c a rd s can r e s u l t in lo s s of le g ib ili ty . A te s t m ethod fo r ev a lu a tio n of c a rb o n -p a p e r ink fo rm u la t io n s th a t w ould y ie ld d a ta on t r a n s f e r c h a r a c t e r i s t i c s w ith a m in im u m o f t e s t s a m p le s u n d e r d y n a m ic c o n d itio n s w as d e s i r e d . M a th e m a tic a l a n a ly s is of th e u se of ra d io iso to p e te c h n iq u e s had in d ic a te d th a t an a d e q u a te m e a s u r e of th e t r a n s f e r w as p o s s ib le . T h e in i t i a l c a lc u la t io n s in d ica ted th a t a dynam ic sy s te m would p robab ly y ield d a ta fo r re la tiv e eva lu a tio n of ink fo rm u la tio n s w ith a m in im um n u m b er of c a rd s , and th a t the d a ta ob ta ined could be id en tified w ith the ac tu a l w eight t r a n s f e r r e d .

S e v e ra l a p p ro a c h e s to th is p ro b le m w e re fe l t to be a p p lic a b le . T h e s e a r e l is te d below , w ith a n a ly se s of th e ad v an tag es and d isa d v a n ta g e s in each tech n iq u e :(1) A dd ition of a ra d io a c tiv e t r a c e r to th e ink fo rm u la tio n . T h is a p p ro a c h r e q u i r e s th e u s e of r e la t iv e ly l a r g e q u a n t i t ie s o f t r a c e r and p r e s e n t s an e q u ip m e n t d e c o n ta m in a tio n p ro b le m .(2) A d d itio n of a n o n - ra d io a c t iv e t r a c e r to th e fo rm u la t io n , p r e p a r a t io n o f th e c a rb o n p a p e r , and su b se q u e n t a c tiv a tio n of th e t r a c e r on th e c a rb o n p a p e r . T h is a p p ro a c h e l im in a te s th e eq u ip m e n t d e c o n ta m in a tio n p ro b le m but would p ro b a b ly r e q u ir e hand ling m o d e ra te ly la rg e q u a n titie s of a c tiv i ty .(3) E s s e n tia l ly id e n tic a l w ith m ethod (2),but the ca rb o n im p re s s io n is t r a n s f e r r e d to th e c a r d b e fo re a c tiv a tio n . T h is a p p ro a c h a p p e a re d to e l im in a te th e p ro b le m d is c u s s e d in connection w ith m e th o d s (1) and (2), but p o se s th e p ro b le m of a c tiv a tio n of th e c a rd s to c k .

278 С . C. THOMAS Jr. et a l.

A p ro g ra m m e to v e r ify th e v a lid ity of th e m a th e m a tic a l c a lc u la tio n w as u n d e r ta k e n . T he c a rb o n p a p e r s te s te d w e re of fo u r d if fe re n t fo rm u la tio n s ,

^d esig n ated ty p e s А, В, С and D . One of th e s e , ty p e A, w as know n to have p o o r t r a n s f e r c h a r a c te r i s t i c s , w hile type В w as be lieved to have good t r a n s f e r c h a r a c te r i s t i c s .

2. EX PER IM EN TA L PROGRAMME\

A s th e f i r s t p h a s e o f th e p r o g ra m m e , i t w as n e c e s s a r y to c a r r y ou t a c t iv a t io n a n a ly s e s to d e te r m in e th e m a jo r a c t iv i t ie s in d u c ed by n e u tro n i r r a d i a t i o n in th e t e s t c a rb o n p a p e r s and th e c a r d s to c k . S a m p le s of th e c a rb o n p a p e r w e re i r r a d ia te d and th e g a m m a - ra y s p e c t r a w e re m e a s u re d to d e te r m in e th e m a jo r a c t iv i ty p r e s e n t . In a d d itio n , d e c a y c u r v e s w e r e a ls o o b ta in e d , u s in g b o th b e ta - and g a m m a -c o u n tin g te c h n iq u e s . T h e s e s tu d ie s w e re c a r r ie d out u sin g sa m p le s of the ca rbon p a p e rs , ca rb o n sc rap ed off th e p a p e r s , and c a rb o n t r a n s f e r r e d to a s e p a r a te s h e e t of p a p e r . In no c a s e w as th e r e an y m a jo r d if fe re n c e in th e g a m m a - r a y s p e c t r a . T y p ic a l g a m m a - ra y s p e c t r a fo r th e ty p e s A and В c a rb o n p a p e r s a r e p re s e n te d in F ig . 1. T h e e n e r g ie s c o r re s p o n d in g to th e m a jo r p e a k s a r e a ls o show n in F i g . l . T h e g a m m a - r a y s p e c t r a of th e ty p e -A and ty p e - В p a p e r s a r e e s s e n tia lly id e n tic a l. F ig . 2 show s a ty p ic a l decay cu rv e obtained on th e type-A c a rb o n p a p e r . A n a ly s is of th e g a m m a - r a y s p e c t r a and th e d e c a y c u r v e s

CHANNEL No.

F ig .l

Gamma-ray spectra of carbon images


TIME (h)

Fig. 2

C aibon im age activ ity decay curve --------- Original c u r v e . ---------- First resolved curve (T i = 15 h subtracted).

------------- Second resolved curve (Tj. = 15 h and T j = 2 .5 h subtracted).

in d ic a te s th a t th e a c t iv i t ie s p r e s e n t a r e due to so d iu m -2 4 , m a n g a n e s e - 56, and c h lo r in e -3 8 . "íhe h a i f - l iv e s a r e 15 h, 2 .5 h , and 38 m in , r e s p e c tiv e ly . T he a c tiv ity le v e ls induced in the ir ra d ia t io n w ere deem ed to be su ffic ien tly h igh to in d ic a te th a t no ad d itio n a l t r a c e r would be r e q u ire d to c a r r y out the e x p e r im e n t.

S am p les of n e u tro n - ir ra d ia te d c a rd s to c k exh ib ited g a m m a -ra y s p e c tra e s se n tia lly id e n tic a l to the ca rb o n p a p e rs . H ow ever, the to ta l ac tiv ity induced w as c o n s id e ra b ly h ig h e r th an th a t of th e c a rb o n -p a p e r s a m p le s , on an equa l w eight b a s is .

A s e r i e s o f e x p e r im e n ts w as ru n to d e te r m in e th e a b i l i ty o f d e te c to r s y s te m s to d is t in g u ish b e tw een th e a c tiv ity on a c a r d and a c tiv ity on a t e s t w h e e l. In th e f i r s t e x p e r im e n t , th e im a g e s w e r e t r a n s f e r r e d to th e c a r d sto ck b e fo re i r ra d ia t io n . The ac tiv ity induced in the c a rd s to ck w as so m uch h ig h e r th a n th e t r a n s f e r r e d im a g e a c tiv ity th a t th e e x p e r im e n t w as not s u c c e s s fu l . In th e seco n d e x p e r im e n t , c a rb o n -p a p e r s a m p le s w e re i r r a d ia te d and th e im a g e w as th e n t r a n s f e r r e d to u n i r r a d ia te d c a r d s to c k . T h e t e s t w heel w as ro lle d o v e r th e te s t c a rd s and the a c tiv ity le v e l on th e w heel w as m e a s u re d w ith the te s t c a rd in p o s itio n and rem o v e d . T he sam e e x p e rim e n t w as re p e a te d w ith th e te s t c a rd in p osition and an inac tive w heel. The r e s u lts of th e s e t e s t s in d ic a te d th a t a s im p le G M -d e te c to r s y s te m w as ab le to d e te r m in e a d e q u a te ly th e in c r e a s e due to th e c a rb o n on th e w h ee l u n d e r th e p ro p o se d t e s t co n d itio n s . The w heel w as ro lle d o v e r eigh t im p rin te d c a rd s , w ith a m e a s u re m e n t o f th e c a rb o n t r a n s f e r a c t iv i ty a f t e r e a c h c a r d . T h e a c tiv i ty le v e l on th e w heel in c re a s e d r a th e r u n ifo rm ly w ith ea ch t e s t c a rd . T he r e s u l t s of th e s e t e s t s and th e e x c e s s iv e a c tiv ity induced by n e u tro n i r r a d ia t io n of c a rd s to c k in d ic a te d th a t th e c a rb o n im p r e s s io n w ould h av e to

280 С . C. THOMAS Jr. et a l.

be t r a n s f e r r e d to th e c a r d a f te r i r r a d ia t io n . H o w ev er no ad d itio n a l t r a c e r w ould b e r e q u ir e d to a t ta in a su f f ic ie n t le v e l of a c tiv i ty a f te r i r r a d ia t io n .

T h e r e s u l t s o f th e t e s t s w e r e u se d to d e s ig n a d e t e c to r m o n ito r in g sy s te m . T he d e te c tin g m o n ito rin g s y s te m and th e a s so c ia te d equ ipm en t s e t up fo r the e x p e r im e n ta l ru n s a re shown in F ig . 3. The d e te c to r-m e a su re m e n t

LAB MONITOR

GM DETECTOR

Fig-3

Schem atic diagram of experim ental apparatus

s y s te m c o n s is te d of a GM tu b e , a T r a c e r l a b m o n ito r (u se d e s s e n t i a l ly a s a h ig h v o lta g e p o w e r supp ly ), a B a ird A to m ic p r e c is io n c o u n t - r a te m e te r , and a B r is to l r e c o r d e r . T he c o u n t- r a te m e te r t im e c o n s ta n t could be v a r ie d f ro m 0 .3 s to 100 s . It h a s s c a le ra n g e s f ro m 30 to 1 ХЮ6 cpm fu ll s c a le . A c h a r t sp e e d of 30 in /m in w as u se d in one s e r i e s o f t e s t s and 35 in /m in in a n o th e r .

A n e v a lu a tio n of th e d e te c to r - m e a s u r e m e n t s y s te m w a s m a d e u s in g the te s t sy s te m and s ta n d a rd s o u rc e s . T he sy s te m re sp o n se c h a r a c te r is t ic s d e te rm in e d w ith th e s ta n d a rd s o u r c e s w e re found to be a d e q u a te . F u r th e r p r e l im in a r y t e s t ru n s w e re m ade u sin g the ty p e -A p a p e r . The f i r s t run w as m ade w ith p a p e r th a t had been ir ra d ia te d fo r 30 m in at a flux of 1 X 1012 n /c m 2 s . T h e ru n w as r e a s o n a b ly s a t i s f a c to r y in th a t th e t r a n s f e r o f c a rb o n w as fo llo w ed by th e d e t e c to r . One p ro b le m w ith th i s ru n w as th a t th e a c t iv i ty le v e l in th e c a rb o n p a p e r w as not h igh enough. It w as fe lt th a t b e t te r r e s u l t s co u ld b e o b ta in e d w ith p a p e r i r r a d ia te d f o r lo n g e r p e r io d s o r a t a h ig h e r f lu x . F o r th i s r e a s o n a se c o n d p r e l im in a r y ru n w as m a d e w ith p a p e r i r r a d ia te d f o r 30 m in w ith 1 X 1 0 13 n /c m 2 s . R uns w e re m a d e w ith 25 and 75 c a r d s .

T h e r e s u l t s o b ta in e d in th e se co n d t r i a l ru n w e re u se d a s a g u id e f o r th e e x p e r im e n ta l r u n s . T h e t e s t c o n d itio n s w e re a s fo llo w s:(1) C a rd s o r t e r sp e e d — 230 c a r d s /m in .(2) C o u n t- r a te m e te r t im e c o n s ta n t — 1 s .

DETERMINATION OF CARTON PAPER TRANSFER CHARACTERISTICS 281

(3) R e c o r d e r c h a r t sp e e d — 30 to 35 in /m in .(4) N e u tro n f lu x — 1. 0 X 10la n /c m ¿ s .(5) I r r a d ia t io n t im e — 1. 75 to 2 h .F ig . 4 show s e x a m p le s of ty p ic a l r e c o r d e r t r a c e s of e x p e r im e n ta l ru n s fo r ty p e s С an d D c a rb o n p a p e r s . T h e d a ta f ro m th e v a r io u s r u n s a r e show n in T a b le I .

CHART TRAVEL (In)---------- TIME

Fig. 4

Reaorder traces o f experim ental runs Sorter speed - 230 cards per m in. C hart speed - 35 in /m in . R atem eter tim e constant - 1 s.

---------- Type D carbon, 100 caids. ------------ Type С caibon, 78 cards.

TABLE I

COMPARISON OF SORTER RUNS

Caibon A A В С D

Number o f caids 76 100 100 78 100

Sorter speed (caids/m in) 230 230 230 230 230

C hart speed (in /m in ) 30 35 35 35 35

C aids, 0 .5 in. 3 .83 3 .2 9 3 .29 3.29 3 .2 9

Range fa ll scale (Kcpm) 30 30 10 10 10

Scale factor (cpm) 3000 3000 1000 1000 1000

Irradiation tim e (h) 2 2 1.75 2 1.75

Neutron flux (n/cm * s) I X 10* 1X 10» 1X 10° 1x10й 1 x 1 0 "

Specific ac tiv ity (cpm /m g) 1500 1120 612 1456 710

3. C A L IB R A T IO N P R O C E D U R E

T h e p ro c e d u re u s e d to c o n v e r t c o u n tin g d a ta in to m a s s t r a n s f e r c o n s is te d of t r e a t in g th e i r r a d ia te d c a rb o n p a p e r w ith h o t tr ic h lo ro e th y le n e to

282 С . С . THOMAS Jr. et a l.

d is s o lv e th e c a rb o n f o rm u la t io n f ro m th e p a p e r b a c k in g . T h e liq u id w a s t r a n s f e r r e d to a ta re d p la n c h e t and e v a p o ra te d to d r y n e s s , and th e re s id u e w as w eighed . The sp e c if ic a c tiv ity of th is re s id u e (cpm /m g) w as d e te rm in ed , u s in g th e d e te c to r s y s te m . S e v e ra l ty p ic a l c a l ib r a t io n r u n s a r e show n in F i g . 5.

Ь Ao 2- <Id

in 1- t- ec < x и

CHART TRAVEL (in )«-----TIME

Fig. 5

Recorder traces of calibra tion runs

Carbon Scale factor W eight T im e const.

Type A 3000 18 .9 m g 0 .3 sType D 1000 6 .2 mg 0 .1 s

4 . ANALYSIS O F DATA

A n a p p ro x im a tin g p o ly n o m in a l e q u a tio n w a s f i t te d to th e p e a k v a lu e s of th e r e c o r d e r t r a c e s by th e l e a s t - s q u a r e s m ethod u s in g an IBM 1620 com - p u to r . T he p ro g ra m m e f its a po lynom inal of the fo rm Y=Ao+Ai X+ ^ Х а+ . . . AgXa w ith a m in im um sum of the sq u a re s of the re s id u a ls . A dditional h ig h e r-o rd e r t e r m s a r e ad d e d s te p - w is e and th e r e s u l t in g r e s id u a l su m o f s q u a r e s i s c o m p a re d to a m a x im u m v a lu e sp e c if ie d by th e p r o g r a m m e r . T he ad d itio n o f h ig h e r - o r d e r t e r m s i s co n c lu d e d w hen th e r e s id u a l su m o f s q u a r e s i s l e s s th a n o r e q u a l to th is sp e c if ie d v a lu e . T h e p r o g ra m m e h a s a c a p a c ity of 100 da tu m p o in ts w ith a m a x im u m ex p an sio n to th e 9th d e g re e te r m . T he p r in t-o u t i s in f lo a tin g p o in t a r i th m e tic w ith an e ig h t-d ig it m a n tis s a . In th e r e s u lt in g p o ly n o m in a l r e g r e s s io n equ a tio n :

Y = coun t r a te (cpm ),X = d is ta n c e u n its on th e r e c o rd t im e s c a le .

F ro m th e know n c h a r t sp e ed and c a r d - s o r t e r sp e ed , th e X u n its w e re co n v e r te d to th e n u m b e r o f c a r d s p r o c e s s e d . U s in g th is e s t im a t io n e q u a tio n , th e a c tiv i ty in c r e a s e on th e s o r t e r t r a n s p o r t r o l l e r s in c o u n ts p e r m in u te w as p lo tte d a g a in s t th e n u m b e r of c a r d s p r o c e s s e d in th e ru n (F ig . 6). T he


NUMBER OF CARDS

Fig. 6

Ninth Order p o ly n o m ia l fit Carbon A ---------- Carbon В ---------- Carbon С ------------------ Carbon D ................

Y in te r c e p t o f th e e s t im a t in g p o ly n o m in a l ( th e Ao te rm ) w a s ta k e n a s th e b e s t e s t im a te of th e b ac k g ro u n d c o u n tin g r a t e . T h is w as s u b tr a c te d f ro m th e to ta l co u n tin g r a t e and th e n e t r a t e w a s c o n v e r te d to w eig h t o f c a rb o n t r a n s f e r r e d by m e a n s of th e c a l ib r a t io n d a ta . T h e w eig h t of c a rb o n t r a n s f e r r e d i s p lo tted a g a in s t th e n u m b e r of c a r d s p ro c e s s e d in th e v a r io u s ru n s in F i g . 7.

NUMBER OF CARDS

Fig. 7

Carbon transfer versus number of cards processed

284 С . С . THOMAS Jr. et a l .

5. DISCUSSION

A s c a n b e s e e n f ro m F ig s 6 an d 7, th e r a d io t r a c e r te c h n iq u e c a n be u se d to e v a lu a te th e r e la t iv e t r a n s f e r of c a rb o n f ro m th e c a r d s to c k to th e w h e e ls of th e s o r t e r w ith a m in im u m n u m b e r of c a r d s .

T h e tw o ru n s w ith th e ty p e -A c a rb o n do no t show a s h ig h a d e g r e e of re p ro d u c ib ility a s would be d e s ir e d . It should , how ever, be noted th a t th e se ru n s w e re m a d e a t d if fe re n t t im e s w ith so m e v a r ia t io n s in p ro c e s s in g co n d i t io n s . I t i s f e l t th a t w ith so m e m o d if ic a t io n s in th e t e s t p r o c e d u r e th i s d if f ic u lty ca n b e o v e rc o m e . In p a r t i c u la r , h ig h e r s p e c if ic a c t iv i t ie s w ould im p ro v e th e c o u n t in g - ra te d e te rm in a t io n s . S e v e ra l a p p ro a c h e s to th is a r e now being in v e s tig a te d . T h e se in c lu d e the add ition of s m a ll q u a n titie s ( le s s th a n 0.5% ) of so d iu m c h lo r id e to th e ink fo rm u la tio n and th e u se of ca rb o n - p a p e r b a c k in g s w ith h ig h e r r a d ia tio n r e s i s ta n c e th a n th e p a p e r u se d in th e p r e s e n t s tu d y . H ig h e r sp e c if ic a c t iv i t ie s m ig h t a ls o e l im in a te th e n eed fo r c o m p u to r a n a ly s is of th e d a ta .

T he d a ta ob ta ined to d a te in d ic a te s th a t the t r a n s f e r m echan ism is ra th e r c o m p lex . In one c a s e , ty p e -D c a rb o n p a p e r , l i t t le o r no t r a n s f e r o c c u r re d a f t e r 75 c a r d s had b ee n p r o c e s s e d .

6. SUMMARY

A r a d i o t r a c e r te c h n iq u e f o r d e te r m in a t io n of th e t r a n s f e r o f c a rb o n im a g e s fro m tab c a rd s to c a r d - s o r t in g equ ipm ent com ponents u n d erd y n am ic c o n d itio n s h a s b e e n d e m o n s tr a te d . T h e te c h n iq u e c a n p ro v id e a r e la t iv e ev a lu a tio n of th e p e rfo rm a n c e of c a rb o n -p a p e r ink fo rm u la tio n s w ith a m in im u m o f t im e . F u r t h e r m o d if ic a tio n s o f th e te c h n iq u e s sh o u ld r e s u l t in a t e s t p ro c e d u re th a t ca n be u se d on a ro u tin e b a s is fo r c a rb o n p a p e r c le a n lin e s s ev a lu a tio n .

D I S C U S S I O N

P .C . AEBERSOLD (C hairm an): In view of th e in c re a se d u se of au tom atic d a ta -h a n d lin g , th i s i s q u ite a n o v e l a p p l ic a tio n . I h a v e h e a r d o f a l l k in d s o f w e a r s tu d ie s and t r a n s f e r s tu d ie s and I th in k th e r e h a s b ee n so m e w ork d o n e w ith r a d io a c t iv e in k t r a n s f e r , b u t to m y k n o w led g e th i s i s th e f i r s t in s i tu a c t iv a t io n o f i t s ty p e , u s in g im a g e t r a n s f e r .

APPLICATIONS DIVERSES DES RADIOÉLÉMENTS DE COURTE PÉRIODE DANS L 'ÉTUDE DES MÉTAUX

A. KOHNIN ST IT U T DE RECHERCHES DE LA SIDÉRURGIE, SA INT-G ERM A IN-EN - LAYE,

FRANCE


SOME APPLICATIONS OF SHORT-LIVED RADIOISOTOPES IN THE STUDY OF METALS. Some typical applications of short-lived radioisotopes in various m etallu rg ical investigations are described.

A sim ple method of activation analysis has been designed for determ ining the amount of lanthanum in steels, to which m ischm etall had been added during m elting.

A study was carried out to de te rm ine the behaviour o f arsenic, present in sm all am ounts, during the oxidation of iron. The enrichm ent of arsenic at the m etal-ox ide interface was first shown by autoradiography.

A quan tita tive study of the phenom enon was then m ade on oxid ized sam ples irrad iated in a nu c lear reactor, by dissolving successive layers several m icrons thick. By this means it was possible to see that the arsenic concentrates itse lf at the surface of the m eta l where its content m ay be as high as 30 or 40 tim es the in itia l concentration in the alloy.

Research on the growth of m eta llic crystals was carried out by autoradiography. This was possible because the content of an alloying elem ent in the crystals is lower than its content in the m elt from which the crystals are growing. Samples of 2°}o copper-alum inium alloys were m elted, slowly cooled, then quenched during the course of solidification. It was thus possible to show the shape o f the crystals a t various stages of their growth and to re la te this to the tem perature of the alloy as measured by a therm ocouple.

An exam ination was made of convection currents inside large forge ingots. The purpose of this investigation was to confirm the existence of im portant convection currents inside large s teel ingots for forgings, as they solidify. The tests were carried out by introducing a sm all am ount of gold-198 a t various tim es a fter pouring, in ingots of 4 t and of 30 to 60 t. It was possible to see that in large ingots the convection currents were su ffic ien tly strong one hour a fte r pouring to m ix the gold through a large volum e o f the ingot.

APPLICATIONS DIVERSES DES RADIOÉLÉMENTS DE COURTE PÉRIODE DANS L'ÉTUDE DES MÉTAUX. Ce m ém oire se propose de présenter quelques applications typiques des radioélém ents de courte période pour des etudes de natures diverses effectuées sur les m étaux.

Une technique sim ple d 'analyse par activation a é té mise au point pour doser le lanthane dans des aciers ayant reçu une faible addition de m ischm etall au cours de leur fusion.

Une étude se proposait d ’exam iner com m ent se com portaient les faibles quantités d ’arsenic présentes dans le fer au cours de l ’oxydation de ce m é ta l. Un enrichissem ent im portant de l'a rsen ic à l 'in te r fa ce du m e ta l e t de l'oxyde a tout d 'abord é té m is en évidence par autoradiographie.

Grâce à l'em p lo i d ’une technique consistant à activer les échantillons oxydés dans un réacteur nucléaire e t a dissoudre des couches successives de quelques microns d'épaisseur, il a é té possible d 'é tud ie r quan tita tivem ent le phénomène. On a pu ainsi vérifier que l ’arsenic se concentrait dans le m étal, au voisinage de l ’in terface, où sa concentration pouvait atteindre 30 à 40 fois la teneur in itia le de l 'a lliag e .

L’étude de la croissance des cristaux m étalliques a été réalisée par autoradiographie en utilisant le fait que le solide est plus pauvre en élém ents d 'a llia g e que le liquide â partir duquel il prend naissance. Elle a porté sur des a lliages alum in ium -cu ivre refroidis len tem ent, puis trem pés en cours de solid ification; e lle a permis de m ettre en évidence la configuration des cristaux m étalliques à divers stades de leur croissance, et de relier la progression de la solidification à la variation de température de l ’alliage, mesurée par un thermo* couple.

L'étude des courants de convection dans les gros lingots de forge avait pour but de confirm er l'ex istence de courants de convection im portants dans les lingots de forge. Les essâis ont é té réalisés en introduisant une pe tite quantité d ’or-198 à divers mom ents après la fin de la coulée dans des lingots de 4 t ainsi que dans des lingots de 30 â 60 t. On a pu voir qu'une partie im portante de ces gros lingots é ta it encore le siège de courants de convection suffisants, pour répartir l ’or dans un volume important du lingot une heure après la fin de la coulée.

285

286 A. KOHN

РАЗЛИЧНЫЕ ПРИМЕНЕНИЯ КОРОТКОЖИВУЩИХ РАДИОЭЛЕМЕНТОВ ПРИ ИССЛЕДОВАНИЯХ МЕТАЛЛОВ. В этом докладе излагается некоторые типичные виды применения короткоживущих радиоэлементов при исследовании металлов.

Разработан простой метод активационного анализа для определения содерхания лантана в различных марках стали, к которой во время плавки добавляется незначительное количество неочиценной смеси редкоземельных элементов.

Исследовалось поведение мышьяка в период окисления железа с целью изучить, как ведут себя незначительные количества содержащегося в железе мышьяка в этот период. С помощью авторадиографии было установлено прежде всего значительное обогащение мышьяком поверхности раздела металл-окись.

В результате применения метода, заключающегося в активировании окисленных образцов в ядер- ном реакторе и растворении образующихся слоев толщиной в несколько микрон, представилось возможным изучить данное явление в качественном отношении. Удалось проверить, что мышьяк концентрируется в металле рядом с поверхностью раздела, где его концентрация может в 30 - 40 раз превышать первоначальное содержание примеси.

С помощью авторадиографии исследовался прирост металлических кристаллов, с учетом того, что твердое тело более бедно легирующими элементами по сравнению с расплавом, из которого оно образуется. Это исследование касалось медленно охлаждаемых сплавов аллюминия и меди, которые затем получали закалку в процессе затвердения. Исследование позволило выявить конфигурацию металлических кристаллов на различных стадиях их прироста и установить зависимость процесса затвердения от изменения температуры сплава, измеряемой с помощью термопары.

Изучение конвективных токов а больших слитках для поковки имело целью подтвердить наличие значительных конвективных токов в слитках для поковки. Опыты были поставлены следующим образом. В различные периоды времени после плавки в слитки весом 4 т, а также в слитки весом 30 - 60 т вводилось радиоактивное золото-198 в незначительных количествах. Можно было заметить, что значительная часть этих больших слитков продолжала оставаться охваченной конвективными токами, достаточно сильными для того, чтобы распределить золото в большом по объему слитке спустя час после окончания‘плавки.

APLICACIONES DE LOS RADIOELEMENTOS DE PERIODO CORTO EN EL ESTUDIO DE LOS METALES. La m em oria expone algunas aplicaciones típ icas de los radioelem entos de período corto en diversos tipos de estudios m etalograficos.

Se ha desarrollado una técn ica sencilla de análisis por activación que perm ite determ inar e l lantano en los aceros a los que se ha añadido una pequefia cantidad de m ischm etall durante la fusión.

Se ha estudiado e l com portam iento de pequeñas cantidades de arsénico presentes en e l hierro durante la oxidacion de este m e ta l y se ha comprobado por autorradiograffa que e l arsénico se concentra notablem ente en la interfaz m etal-óxido.

M ediante una técn ica que consiste en activar las muestras oxidadas en un reactor nuclear y disolver capas sucesivas de algunas m ieras de espesor, e l fenómeno se ha podido estudiar cuantitativam ente. Así se ha com probado que e l arsénico se concentra en las proxim idades de la superficie de los granos m etálicos, alcanzando hasta 30 o 40 veces la concentración m edia in ic ia l correspondiente a la aleación.

Se ha realizado un estudio de l crecim iento de los cristales m etálicos por autorradiograffa aprovechando e l hecho que e l sólido es más pobre en elementos aleados que e l líquido a partir del cual los cristales se forman. Se han estudiado aleaciones a lum inio-cobre enfriadas lentam ente y tem pladas durante la so lidificación, lo cual perm itió poner en ev idencia la configuración de los cristales m etálicos en diversas etapas de su c re c im iento, y establecer la relación que existe entre e l progreso de la solidificación y las variaciones de tem peratura de la a leación , m edidas m ediante un term opar.

F inalm ente, se han estudiado las corrientes de convección en lingotes de forja de grandes dimensiones. La finalidad de este trabajo era confirm ar que en los lingotes de forja se producen fuertes corrientes de convección. Los ensayos se realizaron introduciendo una pequeña cantidad de oro-198 radiactivo en lingotes de 4 t y en lingotes de 30 a 6 01 en diversos m omentos después de la colada. En muchos de estos lingotes, se re gistraron corrientes de convección de intensidad suficiente para distribuir e l oro por gran parte d e l volum en d e l lingote una hora después de term inada la co lada.

APPLICATIONS DIVERSES DES RADIOÉLÉMENTS DE COURTE PÉRIODE 287

INTRODUCTION

De n o m b re u se s r e c h e r c h e s s u r le s m é tau x ou le s p ro c e s s u s m é ta l lu r g iq u e s o n t d é jà é té r é a l i s é e s g r â c e au m o y e n d e s r a d io is o to p e s , s o i t à l ’é c h e l le du l a b o r a to i r e , s o it à l ’é c h e l le in d u s t r ie l le . L a s u c c e s s io n d e s d iv e r s e s o p é ra tio n s g é n é ra le m e n t n é c e s s i té e s p a r c e s é tu d es ex ige h a b itu e l le m e n t un d é la i a s s e z long , e t c ’e s t p o u rq u o i on p e n s e so u v en t que s e u ls d e s r a d io é lé m e n ts de longue p é r io d e p eu v e n t c o n v e n ir p o u r c e s t r a v a u x . C e p e n d a n t, d a n s b ie n d e s c a s , il . e s t p r é f é r a b le d ’u t i l i s e r d e s é lé m e n ts r a d io a c t i f s à p é r io d e r e la t iv e m e n t c o u r te . E n e ffe t, c e u x - c i o f f re n t deux a v a n ta g e s p r in c ip a u x :

1. L e s é lé m e n ts à c o u r te p é r io d e son t, en g é n é ra l, d e s é lém e n ts ayant un e se c tio n e f f ic a c e é le v é e e t i l e s t p o s s ib le de r e n d r e c e s é lé m e n ts su ff isa m m e n t ra d io a c tifs , m êm e lo r s q u ’i ls ne so n t p ré s e n ts qu ’en q u an tité s ex t r ê m e m e n t p e t i te . A u s s i , ch a q u e fo is q u e le m é ta l p r in c ip a l c o n s t i tu a n t l ’a l l ia g e p r é s e n te un e fa ib le se c tio n e ff ic a c e au x n e u tro n s ( c ’e s t en p a r t i c u l ie r le c a s du fe r ) , on peu t u t i l i s e r la techn ique d ’ac tiv a tio n .C ette m éthode, qu i c o n s is te à p la c e r le s éc h an tillo n s , p ré a la b le m e n t p ré p a ré s , dans le flux de n e u tro n s d ’un r é a c te u r n u c lé a ire , a l ’av an tag e de p e r m e t t r e d ’e f fe c tu e r l a m a je u r e p a r t i e d e s o p é r a t io n s d e p r é p a r a t io n d e s é c h a n t i l lo n s s u r un m a té r ia u in a c tif , év ita n t a in s i l e s in c o n v én ie n ts qu i peuven t r é s u l t e r de la m a n ip u la tio n de p ro d u its r a d io a c t i f s , e t la n é c e s s i té de p r e n d r e d e s p r é ca u tio n s p o u r se p ré m u n ir c o n tre le d an g e r des rayonnem en ts qu ’i ls ém etten t.

2. D ans c e r ta in e s é tu d e s in d u s t r ie l le s , i l e s t so u h a ita b le de m a rq u e r un e c e r ta in e f r a c t io n de l a p ro d u c tio n avec un ra d io é lé m e n t. Si la p é r io d e d e c e lu i - c i e s t r e la t iv e m e n t c o u r te , son a c t iv i té d i s p a r a î t r a r a p id e m e n t p a r d é c r o is s a n c e n a tu r e l le , a v a n t m ê m e qu e l e s p r o d u its c o n ta m irié s n e so ie n t s o r t i s de l ’u s in e . On é v i te r a a in s i d ’a v o ir à s to c k e r c e s p ro d u its un c e r ta in te m p s av a n t le u r l iv r a is o n , ou d ’a v o ir à s e p ré o c c u p e r d e s c o n d it io n s de le u r u t i l is a t io n .

C et exposé s e p ro p o se de p r é s e n te r q u a tre ex em p les d iffé ren ts d ’em plo i d e s ra’d io é lé m e n ts à c o u r te p é r io d e dans le dom aine m é ta llu rg iq u e ; c e u x -c i on t é té u t i l i s é s d a n s c e s a p p l ic a tio n s , so it p o u r le s m o tifs p ré c é d e m m e n t ex p o sés, so it p a rc e que la n a tu re m êm e de l ’é lém en t étud ié n é c e s s ita it l ’em p lo i d ’un iso tope qui se tro u v a it a v o ir une co u r te p é rio d e .

A . EXAMEN DE LA FORMATION DES CRISTAUX METALLIQUES

N a tu re du p ro b lèm e étud ié

C e r ta in e s d e s p r o p r ié té s e t d e s d é fa u ts que peuven t p r é s e n te r le s a l l i a g e s m é ta l l iq u e s d ép e n d en t des" p h én o m èn e s q u i s e p ro d u is e n t au m o m e n t où s e so lid if ie n t c e s m é ta u x , o b te n u s l iq u id e s à p a r t i r d e s m a t iè r e s p r e m iè r e s . L e s f a c te u r s q u i rè g le n t la so lid if ic a tio n d e s a l l ia g e s so n t e n c o re t r è s m a l connus en ra is o n de la d ifficu lté de le u r étude e t de la te m p é ra tu re é lev é e à la q u e lle a lie u la so lid ific a tio n d e s m é tau x in d u s tr ie ls le s p lus cour a n ts , com m e l ’a lu m in iu m e t l ’a c ie r .

L ’e m p lo i d e s é lé m e n ts r a d io a c t i f s , en c o m b in a iso n a v e c d if f é r e n te s a u t re s m éthodes [2 ] , p e rm e t d ’a p p o r te r d es é lé m e n ts d ’in fo rm atio n p a r tic u -

288 A. KOHN

l i è r e m e p t u t i l e s c o m m e on v a le v o i r p a r l ’e x e m p le su iv a n t. D an s c e t te étude r é a l is é e au la b o ra to ir e s u r de p e tits éch an tillo n s , on a u ti l is é la te c h n ique a u to ra d io g rap h iq u e p o u r « v o i r » le s c r is ta u x en t r a in de c ro ît re .N o u s avons t i r é p a r t i du fa it , connu d epu is lon g tem p s, que d e s c r is ta u x d ’un a l l i ag e on t, au d éb u t de l a so lid if ic a tio n , une co m p o sitio n ch im iq u e d if fé re n te de c e lle du m é ta l liq u id e à p a r t i r duquel i l s s e fo rm e n t.

C on d itio n s d e s e s s a i s

L e s e s s a i s o n t é té e f fe c tu é s en u t i l i s a n t un d is p o s i t i f c o m p o r ta n t un su p p o r t v e r t i c a l f ix e s u r le q u e l é ta i t p la c é le c r e u s e t r e n fe rm a n t l ’a l lia g é , e t un en sem b le m obile p o rta n t le fo u r d es tin é à r é a l i s e r la fu sion de l ’échanti l lo n e t un r é c ip ie n t r e m p l i d ’e a u . C e t e n s e m b le p o u v a it ê t r e a n im é d ’un m ouvem ent q u i p e rm e tta i t d ’é c l ip s e r t r è s ra p id e m e n t le fo u r, e t de le r e m p la c e r p a r le ré c ip ie n t re m p li d ’eau , a s s u ra n t a in s i un re f ro id is se m e n t t r è s ra p id e du m é ta l au m om en t voulu.

N o tre é tude a p o r té s u r un a llia g e d ’a lu m in iu m à en v iro n 2% de c u iv re . Une p e t i te q u a n tité de m é ta l d ’e n v iro n 40 g é ta i t fondue d an s un c r e u s e t en alum ine; lo rsq u e le m é ta l é ta it liqu ide,on p longeait au c e n tre de l 'é c h an tillo n u n th e rm o c o u p le ’ c h r o m e l- a lu m e l d e s t in é à m e s u r e r s a t e m p é r a tu r e . L e co u p le , dont l a so u d u re é ta i t nue (des e x p é r ie n c e s a n té r ie u r e s a v a ie n t, en e ffe t, m o n tré q u ’i l n ’y a p a s de r é a c tio n c h im iq u e e n tre l e s f i l s du coup le e t l ’a l lia g e exam iné), é ta i t r e l ié à un p o te n tio m è tre e n r e g is t r e u r s u r leq u e l s ’in s c r iv a i t , en con tinu , la co u rb e de v a r ia tio n de la te m p é ra tu re de l ’a l l i age lo rsq u e c e lu i- c i se r e f ro id is s a i t . E n ra iso n du con tac t d ire c t qui ex is te e n t re la so u d u re du coup le e t l ’a l lia g e , i l n ’y a p ra tiq u e m e n t aucune in e r t ie th e rm iq u e e t l a te m p é r a tu re ind iquée c o r re sp o n d b ien à c e lle qu i e x is te au c e n tr e de l ’é c h a n tillo n au m om en t c o n s id é ré .

L a c o u rb e d e s o lid if ic a tio n d ’un te l a l l ia g e (v o ir f ig . 1) e s t c o m p o sé e de t r o is tro n ç o n s d is t in c ts r a c c o rd é s p a r des co u rb e s dont le rayorl de c o u rb u re dépend d es con d itio n s e x p é r im e n ta le s de l ’e s s a i e t de la te n e u r en é lé m e n ts d ’a l lia g e du m é ta l . L e p r e m ie r tro n ç o n « a b » c o r re sp o n d au r e f r o i d is s e m e n t à l ’é ta t liq u id e de l ’échan tillon ; le deux ièm e tro n ço n « c d » r e p r é se n te la so lid ifica tio n de l ’a l lia g e . Enfin, le tro is iè m e tro n ço n « e f » c o r r e s pond au re f ro id is s e m e n t du m é ta l à l ’é ta t so lid e . D ans le ca s de ce s a llia g es , le début de la so lid ifica tio n e s t indiqué p a r un p e tit c ro c h e t « b c » c o rre sp o n d an t à la s u r fu s io n , e t la f in p a r un a u t r e c ro c h e t « d e » in d iq u an t le dépôt d ’u ne p e t i te q u a n tité d ’e u te c tiq u e .

L e s e s s a is ont c o n s is té à r é g le r le re f ro id is s e m e n t du fo u r, pou r ob ten i r d ’a b o rd u n e so lid if ic a tio n t r è s le n te du m é ta l p ré a la b le m e n t fondu . On s u iv a it l ’év o lu tio n du p h én o m èn e d ’a p r è s la c o u rb e q u i s ’in s c r iv a i t s u r le p o te n t io m è tre e n r e g i s t r e u r ; p u is , à un c e r ta in s ta d e d e l a so lid if ic a tio n , on t r e m p a it b ru ta le m e n t l ’éc h an tillo n en m anoeuvran t le d isp o s itif p e r m e tta n t de r e m p la c e r le fo u r p a r le ré c ip ie n t re m p li d ’eau .

Au c o u r s du r e f ro id is s e m e n t le n t, de g ro s c r is ta u x co m m en ça ien t à se d év e lo p p e r au se in du m é ta l fondu; p u is , au m om en t de la tre m p e , le m é ta l e n c o re liq u id e s e s o lid if ia i t t r è s ra p id e m e n t p a r la fo rm a tio n de t r è s no m b re u x c r is ta u x m in u s c u le s .

APPLICATIONS DIVERSES DES RADIOELEMENTS DE COURTE PERIODE 289

Figure 1

Courbe d 'analyse therm ique d 'un a lliag e a lum in ium -cu iv re à 2#> C u.

P ré p a r a t io n d e s a u to ra d io g ra p h ie s

D ans c e s é c h a n tillo n s , n o u s a v o n s p r é le v é d e s p la q u e tte s q u i on t é té so ig n e u sem en t p o lie s , p u is p la c é e s dans le flux de n e u tro n s du r é a c te u r nu c l é a i r e E L 2 d e S a c la y ; d a n s 'c e s c o n d itio n s , l ’a lu m in iu m s ’a c t iv e p a r l a ré a c tio n ¿7Á1 (n, y) 28Al,en donnant n a is sa n c e à un rad ioa lum in ium de pério d e 2 ,30 m in , dont l ’a c tiv i té d is p a r a î t t r è s ra p id e m e n t a p r è s la f in de l ’i r r a d i a t io n . L e c u iv re s ’a c tiv e en d o n n an t n a is s a n c e , s u iv a n t la r é a c t io n 63Cu (n, 7 ) 64ç:u à un r a d io c u iv r e d e p é r io d e 1 2 , 8 h .

S i l ’on e ffe c tu e d e s a u to ra d io g ra p h ie s d a n s l e s 48 h e u r e s q u i su iv e n t l a f in d e l ’i r r a d ia t io n , on o b tie n t d e s im a g e s q u i m o n tr e n t la r é p a r t i t io n de c u iv re dans la p la q u e tte i r r a d ié e . On peu t, de c e tte m a n iè re , d is t in g u e r le s g ro s c r is ta u x fo rm é s au c o u rs du re f ro id is s e m e n t le n t, qui a p p a ra is s e n t n e tte m e n t s u r le s a u to ra d io g ra p h ie s p a r su ite de l e u r te n e u r p lu s fa ib le en c u iv re . L e m é ta l, qu i é ta it e n c o re liqu ide au m om ent o ù l ’on a t r e m p é l ’échan- til lo n , a p p a ra ît so u s fo rm e d ’un fond g r i s â t r e u n ifo rm e . E n effe t, l ’h é té ro g é n é ité de ce m é ta l com posé de c r is ta u x m in u scu le s se s itu e a u -d e sso u s du p o uvo ir de sé p a ra tio n de l ’im age au to rad io g rap h iq u e .

L a f ig u re 2 r e p r é s e n te d e s a u to ra d io g ra p h ie s a g ra n d ie s o b te n u e s s u r d e s éc h a n tillo n s p r é p a ré s p a r la tech n iq u e qu i v ie n t d ’ê t r e d é c r i te e t t r e m p é s à d i f f é r e n ts s ta d e s de la so lid if ic a tio n . On p eu t, d ’a p r è s c e s im a g e s , « v o i r » c o m m e n t s ’e ffe c tu e l a c r o is s a n c e d e c e s c r is t a u x .

290 A. KOHN

1 - après 10 secondes

_ * L í Z f

2 - après 30 secondes

3 - après 3 m inutes 4 - après 5 m inutes

5 - après 9 m inu tes 6 - après so lid ifica tio n c o m p lè te (29 m inutes)

Figure 2

Autoradiographies m ontrant la croissance des cristaux dendritiques dans un a lliag e alum in ium -cu ivre à 2% Cu.


R é s u lta ts de l ’é tude

L ’ex am en de c e s au to ra d io g ra p h ie s a p e rm is de c o n f irm e r que dans un a llia g e à l ’in té r ie u r duquel i l n ’e x is te qu ’un fa ib le g ra d ie n t de te m p é ra tu re , la so lid ifica tio n s ’effec tue p a r la fo rm a tio n de c r is ta u x iso lé s , p ren a n t n a is s a n c e à p a r t i r de g e r m e s d i s p e r s é s à l ’i n té r i e u r du m é ta l liq u id e , a p r è s que la te m p é ra tu re a i t b a is s é a u -d e là de la te m p é ra tu re n o rm a le de so lid if ic a tio n (phénom ène de su rfu s io n ). C es c r is ta u x se développen t e n su ite indép en d a m m e n t le s u n s d e s a u t r e s en p re n a n t c e tte fo rm e ra m if ié e , p a r t ic u l i è r e aux c r is ta u x d e s a l l ia g e s m é ta l l iq u e s , qu e l ’on a p p e lle « d e n d r i te s » . C e s m ê m e s im a g e s m o n tr e n t c o m m e n t s e d é v e lo p p e n t c e s d e n d r i t e s q u i c r o is s e n t en occupan t rap id e m en t un vo lum e im p o rta n t du liqu ide; la so lid ifica tio n se p o u rsu it e n su ite p a r la ram ific a tio n d es b ran c h es d é jà e x is ta n te s .

L a c o m p a ra is o n e n t r e l e s r é s u l t a t s de l ’é tu d e a u to ra d io g ra p h iq u e e t d e s m e s u re s de te m p é r a tu re s e s t ég a le m e n t in té r e s s a n te , c a r e lle m o n tre que, dans un m é ta l lé g è re m e n t a l l ié com m e c e lu i qui a é té exam iné (e t c ’e s t é g a le m en t le c a s de la p lu p a r t d es a c ie r s de co n s tru c tio n ) , la m a je u re p a r tie , de la so lid if ic a tio n se f a i t p a r la c r o is s a n c e à u n e te m p é r a tu r e s e n s i b le m en t co n s tan te de c r is ta u x à te n e u r un ifo rm e en é lé m e n ts d ’a llia g e , ce tte te n e u r é ta n t p lu s fa ib le qu e c e l le du l iq u id e . C ’e s t s e u le m e n t e n s u i te que la so lid if ic a tio n s e p o u rs u it av ec une v a r ia t io n de te m p é r a tu re p lu s im p o r ta n te au fu r e t à m e s u re que s e so lid ifie le liq u id e d e s e s p a c e s in te rd e n d r i- t iq u e s e n r ic h i en é lé m e n ts d ’a l l ia g e . L a so lid if ic a tio n s e te r m in e lo r s q u e le liq u id e in te rd e n d ritiq u e e s t su ffisam m en t e n r ic h i en cu iv re pour p e rm e ttre le dépôt de l ’eu tec tiq u e a lum in ium — c u iv re .

B . ETUDE DES COURANTS DE CONVECTION DANS LES LINGOTS INDUSTRIELS EN COURS DE SOLIDIFICATION

N atu re du p ro b lèm e étud ié

A u c o u r s de la s o l id if ic a t io n d e s lin g o ts in d u s t r i e l s d ’a c i e r , d o n t le p o id s p eu t v a r i e r e n t r e q u e lq u e s to n n e s e t q u e lq u e s d iz a in e s de to n n e s , i l se p ro d u it d iv e rs phénom ènes en c o re m a l connus, qui se ré p e rc u te n t souvent de façon fâch eu se s u r le s p ro p r ié té s m é ca n iq u es e t la q u a lité du lingo t. D es tra v a u x im p o rta n ts , dont c e r ta in s rem o n ten t à p lus de 35 ans, ont é té consac r é s a l ’exam en app ro fond i de lin g o ts r e f ro id is , afin d ’e s s a y e r de p r é c i s e r l a n a tu re d e s p h én o m èn e s p re n a n t n a is s a n c e au c o u r s d e la s o lid if ic a tio n . M a lg ré le s é lé m e n ts d ’in fo rm a tio n in té r e s s a n ts a in s i r e c u e i l l is , le s r é s u l ta ts de c e s tra v a u x n ’ont p a s e n c o re p e rm is de b ien c o m p re n d re p le in em en t le m é c a n ism e de la so lid if ic a tio n de g ra n d e s m a s s e s de m é ta l, e t le s hypoth è s e s é m is e s p o u r e x p liq u e r le s o b se rv a tio n s ré s u lta n t de l ’exam en de l in g o ts f ro id s s ’appu ien t souven t s u r d e s b a se s b ien in c e r ta in e s .

On a lo n g te m p s a d m is que le m é ta l liq u id e r e m p l is s à n t une l in g o tiè re é ta i t p ra tiq u e m e n t im m o b ile ; c ’e s t s e u le m e n t d ep u is une d iz a in e d ’an n ées qu ’on a é té am ené à p e n s e r que ce m é ta l liqu ide pouvait ê t re le s ièg e de coura n ts de convection im p o rta n ts , un tem p s a s s e z long a p rè s la fin de la cou lée . L a v a lid ité de c e tte hypo thèse a é té c o n firm é e p a r le s é tu d es de c h e rc h e u rs r u s s e s , r é a l i s é e s au m oyen de t r a c e u r s ra d io a c tifs [3, 4 ] .

292 A. KOHN

A lo rs que le s tr a v a u x a n té r ie u r s c o n c e rn a n t l a so lid ifica tio n de l ’a c ie r ca lm é ava ien t é té e ffec tu és s u r des lin g o ts de 7 tonnes au m axim um avec des r a d io é lé m e n ts de longue p é r io d e , no u s avons vou lu p lu s p a r t ic u l iè r e m e n t e x a m in e r l ’e x is te n c e de c e s c o u ra n ts de co n v e c tio n d a n s d e s g ro s lin g o ts de fo rg e de 40 à 60 to n n e s , en u t i l i s a n t c o m m e t r a c e u r un é m e t te u r de r a y o n s y d e c o u r te p é r io d e , l ’o r - 148.

P r in c ip e d e l a m é th o d e d ’e x a m e n

L a m éthode em ployée c o n s is te à in tro d u ire , à un c e r ta in m om en t a p rè s la co u lé e , une p e t i te q u an tité d ’un ra d io é lé m e n t d an s la p a r t ie s u p é r ie u r e du lin g o t en c o u rs de s o lid if ic a tio n . A p rè s r e f r o id is s e m e n t , on s e c tio n n e le l in g o t e t on e x a m in e , s o i t p a r a u to ra d io g ra p h ie , s o it p a r c o m p tag e , la r é p a r t i t io n d e l ’é lé m e n t r a d io a c t i f d a n s d iv e r s e s s e c t io n s du l in g o t .

S i l ’é lém e n t ra d io a c tif a jou té in itia le m e n t en un point d é te rm in é ne pouv a i t s e m é la n g e r dans le m é ta l liq u id e env iro n n an t que p a r le s im p le jeu de la d iffu sion a l ’é ta t liq u id e , i l se tro u v e ra i t r é p a r t i au bout de quelques heur e s d an s une p e t i te s p h è re de se u le m e n t quelques c e n tim è tre s de rayon ; s i l ’on m e t en év idence la p ré s e n c e du ra d io é lé m e n t dans un volum e a s s e z im p o r ta n t du lingo t e t à une a s s e z g ran d e d is tan c e du point d ’in troduc tion , cec i s ig n if ie que l ’é lé m e n t r a d io a c t i f a é té m é la n g é à l ’a c ie r liq u id e p a r su ite de l ’e x is te n c e de c o u ra n ts in te r n e s .

E s s a i s s u r p e t i ts lin g o ts

P o u r m e ttr e au po in t la m éthode, nous avons d ’abo rd effec tué deux e s s a is s u r d es lin g o ts de 4, 1 t dans la S tation d ’e s s a is de l ’IRSID à M a iz iè re s - le s -M e tz . D ans chacun de ce s e s s a is , un p e tit f il d ’o r d ’env iron 0,1 g, p r é a la b le m e n t i r r a d i é d an s le r é a c te u r n u c lé a ire E L 2 de S ac lay , p o u r o b te n ir une a c tiv ité de quelques m il lic u r ie s , ava it é té p lacé dans un capsu le en acier, so u d é e à. l ’e x t ré m ité d ’une longue t ig e é g a le m e n t en a c ie r . On in tro d u is a it c e tte ca p su le dans la p a r t ie s u p é r ie u re de la l in g o tiè re , de m a n iè re qu’e lle v ie n n e s e p la c e r s e n s ib le m e n t d an s l ’axe du lin g o t, au n iv e a u du jo in t de m a s s e l o t t e .

C e tte in tro d u c tio n av a it é té e ffec tu ée im m é d ia te m e n t a p r è s la fin çle la co u lée d an s le p r e m ie r e s s a i , e t 20 m in a p r è s la co u lée d an s le d eu x ièm e e s s a i . L e s d eux l in g o ts ,t r a n s p o r té s chauds p a r cam io n ju sq u ’aux la m in o ir s v o is in s de l ’U . C . P . M . I . , av a ie n t é té la m in é s en b lo o m s de 140 X 1 7 0 m m de se c tio n . A p rè s le la m in a g e ,o n a v a it découpé en d if fé re n te s p o sitio n s des p la q u e tte s qu i, und fo is r e f ro id ie s , fu re n t so ig n e u se m e n t p o lie s s u r l ’une d e l e u r s f a c e s .

On d é te rm in a le s ré g io n s d e s p la q u e tte s qui é ta ie n t ra d io a c tiv e s au m o yen d ’un d isp o s itif de com ptage com prenan t un com pteu r a sc in tilla tio n s muni d ’un c r i s t a l de 25 m m de d ia m è t re , d is p o s é a u - d e s s u s d ’un c o l l im a te u r en p lom b de 100 m m de long e t de d ia m è tre in té r ie u r de 20 m m . L es p laquettes é ta ie n t p la c é e s s u r un p e t i t c h a r io t que 1’ on pouvait d é p la c e r , su iv an t deux d ir e c tio n s p e rp e n d ic u la ir e s , a u - d e s s u s du co m p te u r.

D ’a p r è s le s ta u x de co m p tag e a in s i d é te rm in é s , e t en r e l ia n t le s p o s i t io n s d e s m e s u r e s aux p o s it io n s in i t ia le s d an s le lin g o t, i l fu t p o s s ib le de


t r a c e r d e s c o u rb e s r e p r é s e n ta n t l a r é p a r t i t io n d e l ’a c t iv i té d e l ' o r d a n s l ’e n s e m b le du l in g o t.

D ans le lin g o t qui a v a it r e ç u une ad d itio n d ’o r au m o m en t de la cou lée , l ’é lém e n t ra d io a c tif se tro u v a it r é p a r t i de façon t r è s se n s ib le m en t hom ogène d a n s to u t so n v o lu m e (sau f d an s la p a r t i e e x te rn e , oïi le s m e s u r e s n e p o u v a ie n t p a s ê t r e f a i te s de façon p r é c is e , à c a u se de l ’e ffe t d e b o rd ).

On n ’a r e tr o u v é au cu n e t r a c e d ’a c tiv i té d a n s le s p la q u e tte s p r é le v é e s d an s la m o itié in f é r ie u re du d eu x ièm e lin g o t, m a is le s m e s u re s e ffe c tu é e s s u r le s p la q u e tte s p ré le v é e s dans la p a r t ie su p é r ie u re de ce lingo t ont m ont r é que l ’o r a jo u té 20 m in a p rè s la co u lée s ’é ta i t r é p a r t i d a n s to u te l a p a r t ie s u p é r ie u re (m a sse lo tte ) a in s i q u 'à l ’in té r ie u r d ’un volum e de fo rm e s e n s ib lem e n t conique s ’étendan t ju sq u ’a m i-h a u te u r du c o rp s p r in c ip a l du lingot (v o ir fig . 3).

Figure 3

Vue générale de l'ap p a re illag e u tilisé pour les mesures de taux de com ptage sur la section d 'un noyau foré dans une grosse p ièce de forge.

E s s a is s u r g ro s lin g o ts de fo rge

L e s e s s a i s p ré c é d e n ts ayan t m o n tré la v a lid ité de la m éthode e t p e rm is de c o n f i r m e r en l e s p r é c is a n t le s r é s u l t a t s o b te n u s a n té r ie u r e m e n t , nous avons e n t r e p r i s d e s e s s a is ana logues s u r t r o i s lin g o ts d e fo rg e de r e s p e c t i v e m e n t 32, 40 e t 60 to n n e s , d e s tin é s à la f a b r ic a tio n de c o rp s c re u x . C es

294 A. KOHN

e s s a i s ont é té ex é c u té s avec le co n co u rs de la S ocié té d e s fo rg e s e t a te l ie r s du O e u s o t . Nous avons t i r é p a r t i du fa it q u ’au c o u rs de l ’o p é ra tio n de f o r g eag e , on p ré le v a it un noyau qui d e m e u ra it in u tilisé ; nous avons donc lim ité n o tr e é tude b. l ’ex a m e n de la r é p a r t i t io n de l ’é lé m e n t ra d io a c tif d an s ce no y au a x ia l qui r e s ta i t à n o tre d isp o s itio n ; la p a r t ie p é r ip h é r iq u e co n s titu a n t l a p lu s g r o s s e f ra c t io n du lin g o t é ta i t n o rm a le m e n t u t i l i s é e p o u r l a f a b r i c a tio n p ré v u e .

D e m ê m e que d a n s le s e s s a i s a n t é r i e u r s , on a in tro d u it d a n s chaque lin g o t, un c e r ta in te m p s a p rè s la fin de la coulée , une p e tite cap su le d ’a c ie r f ix é e au bou t d ’une t ig e e t co n ten an t un f i l d ’o r de q u e lq u es c e n tig ra m m e s , re n d u ra d io a c t i f p a r i r r a d ia t io n 'd a n s le r é a c te u r n u c lé a ire E L 2 de S ac lay . S a p o s it io n d ’in tro d u c tio n c o r re s p o n d a it au p la n du jo in t de m a s s e lo t te . L e noyau p ré le v é au c o u rs du fo rg e ag e é ta i t s c ié lo n g itu d in a lem e n t su iv an t une s e c tio n d ia m é tra le e t la s u r fa c e de c e tte se c tio n é ta i t r a b o té e ; la d u ré e to t a le d e s o p é ra tio n s de fo rg e a g e e t de s c ia g e e t ra b o ta g e a pu , chaque fo is , ê t r e ré d u ite à une s e m a in e .

L e s m e s u re s de tau x de com ptage é ta ie n t e ffec tu ée s en dép laçan t s u r la s u r fa c e h o r iz o n ta le du d em i-n o y a u un p e tit c h a r io t su p p o rta n t le c o m p te u r à s c in ti l la t io n s e t son c o l l im a te u r en p lom b (v o ir fig . 4). Il a é té a in s i p o s s ib le d e d é te r m in e r l a r é p a r t i t io n d e l ’a c tiv i té d a n s la s e c tio n d ia m é t ra le d e ch aq u e noyau .

L e s c o n d itio n s d e c e s e s s a is so n t in d iq u é e s d a n s l e ta b le a u I.

R é s u l ta t s d e s e s s a i s

L e s m e s u r e s e f fe c tu é e s s u r le noyau d ’un lin g o t de 40 t , d a n s le q u e l l ’o r r a d io a c t i f a v a it é té in tro d u i t 5 h a p r è s la f in d e l a c o u lé e , on t donné d e s r é s u l ta ts t r è s ana logues à ceux que l ’on ava it p réc éd em m en t obtenus s u r un lin g o t de 4,1 t , où l ’add ition a v a it é té fa ite 20 m in a p rè s la fin de l a coulé e . I l e x is te , dans la m o itié s u p é r ie u re du lingot, une zone rad io a c tiv e dont l 'a c t iv i té d é c r o î t de façon a s s e z r é g u liè re à p a r t i r d ’un po in t m a x im a l s itu é k en v iro n 70% d an s la h a u te u r à p a r t i r du p ied .

L e s r é s u l t a t s o b ten u s s u r deux lin g o ts de 30 e t 60 t, où l ’in tro d u c tio n a v a it é té e ffec tu ée 1 h a p rè s l a cou lée , son t t r è s se m b la b le s . L a p a r t ie in f é r i e u r e du noyau (en v iro n 10% d e l a h a u te u r d an s le lin g o t de 60 t e t 17% d an s le lingo t de 30 t) e s t co m p lè tem en t dépourvue d ’a c tiv ité . D ans la rég ion s i tu é e im m é d ia te m e n t a u -d e s su s , on o b s e rv e d e s v a r ia t io n s ra p id e s d ’a c t iv i té à p a r t i r d ’une p lag e où e l le e s t m a x im a le . Enfin , d an s to u te la p a r tie du noyau , c o m p r is e e n t r e 22 e t 80% de la h a u te u r in it ia le du lin g o t, on o b s e r v e un e a c tiv i té t r è s n e t te s e n s ib le m e n t c o n s tan te (v o ir f ig . 5).

I l p a r a î t p o s s ib le d ’i n t e r p r é t e r le s r é s u l t a t s o b te n u s au c o u r s d e c e s e s s a i s en p e n s a n t que l a c a p s u le en a c ie r non fondu (m a is p r é a la b le m e n t r e m p l ie d e m é ta l l iq u id e ) e s t to m b é e au p ie d du lin g o t en e n t r a în a n t l ’o r ra d io a c ti f ; c e lu i - c i s ’e s t donc d ’ab o rd rép an d u d an s la p a r t ie in fé r ie u re du lin g o t où s a d ilu tio n a é té s to p p é e au bout d ’un m o m e n t p a r l a p r o g re s s io n d e l a s o lid if ic a tio n du p ie d du lin g o t. L ’o r d é jà ré p a n d u d a n s l e s c o u c h e s s u p é r ie u r e s a é té , p a r l a s u ite , so u m is k un b r a s s a g e im p o r ta n t, qu i a eu p o u r e f fe t de p ro v o q u e r un e h o m o g é n é isa tio n p ra tiq u e m e n t co m p lè te de s a c o n c e n tra tio n d an s to u te c e tte p a r t ie du lingo t où le m é ta l é ta i t en c o re com p lè te m e n t l iq u id e .


Figure 4

. Répartition de l 'o r rad ioac tif dans un lingot de 4 tonnes (addition fa ite 20 minutes après la coulée).

L e s r é s u l ta ts de ce s e s s a is m o n tre n t p a r conséquen t de façon m a n ife s te que d a n s d e s lin g o ts de p lu s ie u r s d iz a in e s d e to n n e s , i l e x is te u n e h e u r e a p r è s la fin de l a co u lée d e s c o u ra n ts de b r a s s a g e im p o r ta n ts qui se m a n ife s te n t d an s la p a r t i e ax ia le du lin g o t s u r le s t r o i s - q u a r t s de s a hau teu r, du cô té d e la tê te . C es c o u ra n ts s e m a n ife s te n t e n c o re , m a is avec un e ffe t de b ra s s a g e m o ins in te n se , 5 h e u re s a p rè s la cou lée . L ’im p o rtan ce de c e s cour a n ts de convection e s t te l le qu’i ls ne peuvent p as ne p as av o ir une in fluence s u r le s p h én o m èn e s de s é g ré g a tio n qui se p ro d u ise n t au c o u rs de la s o lid if ic a tio n d e s lin g o ts e t qu i s o n t la c a u s e d e s h é té ro g é n é i té s c o n s ta té e s s u r l e s lin g o ts s o l id if ié s .

C. E T U D E DE L ’EN R IC H ISSEM EN T S U P E R F IC IE L EN A RSENIC DE L ’A C IE R AU COURS DE SON OXYDATION A CHAUD

L ’oxydation d e s m é tau x e s t un p ro b lè m e qui a d é jà fa it l ’o b je t d e n o m b r e u s e s é tu d es . L e co m p o rtem e n t de c e r ta in s é lém e n ts d ’a llia g e ou im p u re t é s p r é s e n t s d a n s le m é ta l d e b a s e n ’e s t c e p e n d a n t p a s to u jo u r s f a c i le à -

296 А. КОНЫ

TABLEAU I

CONDITIONS DES ESSAIS

Essai A Essai B Essai C

Poids to ta l du lingot 40,8 t 32 t 61 t

D iam ètre moyen du lingot 1400 mm 1130 mm 1600 mm

A ctiv ité de l ’addition d ’or (au m om ent

de l'in troduction) 20 m e 75 me 150 me

Temps écou lé en tre la fin de la coulée

e t l'in troduction de l 'o r 5 h 1 h 1 h

Dimensions de '] hauteur 1370 mm 1500 m m 1850 mm

la p ièce forée J d moyen 1800 mm 1600 mm 2000 mm

D iam ètre du noyau 350 mm 350 mm 450 mm

Rapport approxim atif d iam ètre du noyau

/d iam è tre de la p ièce forée 1/5 1 /4 ,5 1 /4 ,5

m e t t r e en év id en ce , n o ta m m e n t lo r s q u ’il s ’ag it d ’é lé m e n ts m o in s oxydab les que lu i . Une é tude q u a lita tiv e a n té r ie u r e [5], r é a l is é e au m oyen de l a te c h n ique a u to ra d io g ra p h iq u e s u r d e s a l lia g e s f e r re u x v a r ié s , av a it m o n tré que d a n s l a p lu p a r t d e s c a s , l ’im p u re té p r é s e n te d an s l ’a c ie r s ’a c c u m u la it au c o u rs de l ’oxydation au v o is in a g e de l ’in te r fa c e m é ta l -o x y d e . L a zone in t é r e s s é e p a r c e tte v a r ia t io n de c o n c e n tra tio n e s t t r è s m in c e , e t s e u le s d es m é th o d es p a r t ic u l iè r e m e n t s e n s ib le s peuven t p e r m e t t r e d ’é tu d ie r q u a n tita tiv e m e n t ce p h é n o m è n e .

D ans le c a d re d ’une é tu d e g é n é ra le p o r ta n t s u r l ’in flu en ce d e s m é ta l lo ïd e s d an s l ’a c ie r , no u s av o n s e x a m in é le c o m p o rte m e n t de l ’a r s e n ic au c o u r s de l ’o x y d a tio n du f e r 16J.

C o n d itio n s d e s e s s a i s

N ous avons u t i l is é d es é c h an tillo n s cy lin d r iq u e s de 12 m m de d ia m è tre e t 6 m m d ’é p a is s e u r d ’un a llia g e f e r - a r s e n ic à 0,075% A s . C es é c h a n ti llo n s é ta ie n t re c o u v e r ts e n tiè re m e n t, sau f s u r l ’une d es fa c e s p lanes soum ise à l 'oxydation , d ’un dépôt é lec tro ly tiq u e de ch ro m e de 40д d ’é p a is se u r .

L ’oxydation d e s é c h an tillo n s a é té e ffec tu ée e n tre 800° e t 1200°C en le s chau ffan t d an s une a tm o sp h è re d ’h yd rogène hu m id ifié , de m a n iè re è o b te n ir l a fo rm a tio n de p e l l ic u le s hom ogènes de p ro to x y d e de f e r F eO .

On a to u t d ’ab o rd exam iné q u a lita tiv e m en t le phénom ène. P o u r e ffec tu er c e s e s s a is , le s é c h an tillo n s oxydés é ta ie n t en ro b é s d an s une ré s in e po lym é- r i s a b l e à f ro id , p u is s e c tio n n é s su iv a n t un p la n p e rp e n d ic u la ir e à la s u r fa c e oxydée . L e s é c h an tillo n s é ta ie n t en su ite so ig n eu sem en t p o lis au p a p ie r


% de métal depuis le pied

Figure S

Répartition de l ‘or rad ioac tif dans le noyau d 'un lingot de 60 tonnes de 1600 m m de d iam ètre (add ition fa ite une heure après la c o u lé e ) .

a b r a s i f e t a l ’a lu m in e , co m m e p o u r le s ex am en s m ic ro g ra p h iq u e s ; p u is i l s é ta ie n t i r r a d ié s d a n s le r é a c te u r n u c lé a ire E L 2 de S ac lay e t m is en e x p o s itio n a u to ra d io g ra p h iq u e . L e s a u to ra d io g ra p h ie s a in s i ob tenues ont n e ttem en t m o n tré q u ’i l y a v a it un e n r ic h is s e m e n t c o n s id é ra b le en a r s e n ic au v o is in a g e de l ’in te r f a c e m é ta l-o x y d e .

P o u r é tu d ie r q u an tita tiv e m e n t le phénom ène, on a i r r a d ié le s é c h a n tillo n s oxydés s a n s le s se c tio n n e r , m a is a p rè s av o ir sé p a ré la p e llicu le dbxyde du m é ta l s o u s - ja c e n t . C e tte o p é ra t io n s ’e f f e c tu a i t a i s é m e n t à f ro id , p a r s im p le a r r a c h e m e n t. L e s é c h an tillo n s ont é té en su ite so u m is à d es a ttaq u e s é le c tro ly tiq u e s s u c c e s s iv e s d an s d e s co n d itio n s p e rm e tta n t de ne d is s o u d re chaque fo is qu’une couche t r è s m in ce s u r le u r su rfa c e p la n e . Chaque attaque; d 'u n e d u r é e d e q u e lq u e s s e c o n d e s , é t a i t e f fe c tu é e d a n s un v o lu m e r é d u i t (10 m l) d ’u n e so lu tio n à 52% d ’a n h y d r id e a c é t iq u e p u r e t 48% d ’a c id e p e r - c h lo riq u e de d e n s ité 1, 60 g /c m 3. On d is s o lv a it a in s i une é p a is s e u r d ’oxyde ou de m é ta l de l ’o r d re de 1 m ic ro n , ce qui c o r re sp o n d a it a une p r is e d ressa i d ’e n v iro n 1 m g .

298 A. KOHN

D ans le s d if fé re n te s so lu tio n s d ’a ttaq u e su c c e ss iv e m e n t u t i l is é e s , on a p r é c ip i té l ’a r s e n ic p a r SH2, a p r è s le u r a v o ir a jo u té un e p e t i te q u an tité de s u lf u r e de m o ly b d èn e d e s tin é e à s e r v i r d ’e n t r a în e u r .

On a d é te rm in é la q u an tité to ta le de m é ta l d is s o u te au c o u rs de chaque a t ta q u e p a r l a p e r te de p o id s d e l ’é c h a n tillo n au c o u r s de c e tte o p é ra tio n . On a d é te rm in é la q u an tité d ’a ra e n ic c o m p ris e d an s le m é ta l d is s o u s d an s chaque p ré c ip ité a l ’aide d ’un co m p teu r G e ig e r-M ü lle r à fe n ê tre d 'a lum inium , e t en c o m p a ra n t l a v a le u r o b s e rv é e à c e lle d ’un p r é c ip i té ob ten u d a n s d e s co n d itio n s s e m b la b le s à p a r t i r du m é ta l de b a s e ( te n e u r de 0,075% d ’a p rè s l ’a n a ly se ch im iq u e ). D ans le s co n d itio n s de c e s m e s u re s , la s e n s ib il i té de l a m é th o d e c o r re s p o n d a it à e n v iro n 0,005% A s.

R é s u lta ts d e s e s s a is

C o n n a issa n t la s u r fa c e de chaque éch an tillo n , i l a é té p o ss ib le , à l ’aide d e s r é s u l t a t s d e s m e s u re s p ré c é d e n te s , de t r a c e r le s c o u rb e s ind iquan t la v a r ia t io n de la te n e u r en a r s e n ic , su iv a n t l ’é p a is s e u r de l ’oxyde e t de l ’é c h a n tillo n . N ous av o n s , p a r a i l le u r s , v é r i f ié que le s p e l l ic u le s d ’oxyde ne p r é s e n ta ie n t aucune a c tiv i té , ni s u r le u r fac e e x te rn e , n i s u r l e u r fac e in te r n e .

L a r é p a r t i t io n de l ’a r s e n ic dans le m é ta l e s t d iffé ren te su ivant que l'oxyd a tio n s ’e s t f a i te à 800°C ( fe r a) ou à 1000°C ( f e r y). Q u e lq u e s e x e m p le s c a r a c t é r i s t i q u e s d e s c o u r b e s o b te n u e s s o n t d o n n é s d a n s l a f ig u re 6 .

Figure 6

R épartition de l'a rsen ic dans le m étal après oxydation dans une atmosphère d 'hydrogène hum ide.


L o rs q u e l ’oxydation s ’e ffec tu e à 800°C, oli l ’a r s e n ic d e m e u re en so lu t io n so lid e d an s l a f e r r i t e , le s c o u rb e s de la r é p a r t i t io n de ee t é lé m e n t ont l a fo rm e r é g u l i è r e d e s c o u rb e s de d if fu s io n e n p h a s e h o m o g è n e . T o u t s e p a s s e , en effe t, com m e s i( au fu r e t à m e s u re de l ’oxydation , l ’a r s e n ic conte n u d an s la p e llic u le qui v ie n t de s ’o x y d er é ta i t c h a s sé v e r s le m é ta l où i l s ’a c c u m u le su iv a n t le s lo is n o rm a le s de la d if fu s io n . C om m e la v i te s s e de d iffu s io n de l ’a r s e n ic d an s le f e r e s t fa ib le , l ’a r s e n ic d if fu se peu v e r s le s co u c h e s p ro fo n d e s de l ’é c h a n tillo n e t s a te n e u r au v o is in a g e im m é d ia t de l ’in te r fa c e p eu t a t te in d re 3%, so it e n v iro n 40 fo is s a te n e u r in i t ia le d an s le m é ta l de b a s e .

L o rs q u e l ’o x y d atio n a é té e ffe c tu é e \ 1000°C en p h a se y, l a c o u rb e de r é p a r t i t io n de l ’a r s e n ic e s t p lu s co m p lex e . L e s o b se rv a tio n s m ic ro g ra p h iq u e s , a in s i que quelques d é te rm in a tio n s lo c a le s fa ite s è la m ic ro so n d e de C asta ing , m o n tre n t que le s c o u rb e s de ré p a r t i t io n de l ’a r s e n ic ob tenues p a r la te c h n ique ra d io a c tiv e n e c o r re sp o n d e n t p a s to u t-à .- fa it à. la r é p a r t i t io n r é e l le . I l e x is te , en effet, une d isco n tin u ité p lu s b ru ta le que ne le m o n tre ce tte courbe, c e l le - c i p a s s a n t d ’une v a le u r d ’en v iro n 1 , 6 % à une v a le u r d ’en v iro n 1 %, p a r su ite de la co e x is ten ce des p h ases a e t y en éq u ilib re . L a cou rbe ex p é rim en ta le , où la te n e u r en a r s e n ic v a r ie p lu s g ra d u e lle m e n t s u r une é p a is s e u r de quelques m ic ro n s , s ’explique p a r le fa it qu’en ra iso n d es i r r é g u la r i t é s de la s u r fa c e de s é p a ra tio n e n tre c e s deux p h a se s , il n ’a pas é té p o ss ib le , au v o is in a g e d e l ’in te r fa c e , d ’a t ta q u e r u n iq u em en t l ’une s a n s a t ta q u e r un peu de l ’a u t r e . E n e ffe t, le s o b se rv a tio n s m ic ro g ra p h iq u e s au x q u e lle s nous avons p ro c é d é , m o n tre n t qu’au c o u rs de l ’oxydation , en ph ase y, l ’e n r ic h is se m e n t en a r s e n ic d ev ien t, à p a r t i r d ’un c e r ta in m o m en t, te l le m e n t im p o r ta n t que l a p h a s e 7 n e p e u t p lu s s u b s i s t e r e t que l a ré g io n e n r ic h ie s e t r a n s f o r m e en fe r . or. Il e x is te , p a r conséquent, à la su rfa c e ex tern e du m éta l, une m ince p e l l ic u le r ic h e en a r s e n ic l ’é ta t de f e r a en é q u i l ib re av ec la p a r t i e p lu s in te rn e d e m e u ré e à l ’é ta t a u s té n itiq u e ( fe r 7 ). A l ’in té r ie u r de ch acu n e de c e s p h a se s , i l e x is te un g rad ie n t de la te n e u r en a rse n ic qui s ’é ta b lit su ivan t le s lo is n o rm a le s de la d iffusion .

D . DOSAGE DU LANTHANE DANS LES ACIERS

N atu re du p ro b lèm e posé

Une é tude e n t r e p r i s e à l ’IRSID, s u r l ’in flu en ce d e s t e r r e s r a r e s a jo u té e s en t r è s fa ib le q u an tité d an s l ’a c ie r , n é c e s s i ta i t le c o n trô le de l a quant i t é de t e r r e s r a r e s re te n u e d an s le m é ta l . P lu tô t que d ’em p lo y e r une te c h n iq u e de c h im ie a n a ly tiq u e c la s s iq u e don t nous n ’a v io n s p a s l a p ra t iq u e e t qui a u ra i t n é c e s s ité une longue m is e au point, nous avons p ré fé ré fa ire appel à une techn ique d ’an a ly se p a r ac tiva tion , dont le s cond itions d ’em plo i é ta ien t beaucoup p lu s com m odes [1 ].

D ans c e tte a p p lica tio n , l ’a n a ly se p a r a c tiv a tio n n ’a p a s é té u t i l is é e en r a is o n d e s a t r è s g ra n d e s e n s ib il i té ,c o m m e c ’e s t le c a s lo r s q u e l ’on v eu t d o s e r d e s t r a c e s d ’é lé m e n ts d a n s d e s m é ta u x e x t r ê m e m e n ts p u r s , m a is p a rc e que l ’un d e s é lém e n ts c o n s titu tifs de m élange à d o se r pouvait s ’a c tiv e r d e faç o n t r è s co m m o d e e t p e r m e t t r e u n e d é te r m in a t io n q u a n ti ta t iv e a v e c u n e bonne p r é c is io n s a n s n é c e s s i t e r d e s o p é ra tio n s c h im iq u e s c o m p le x e s .

300 A. KOHN

I l s ’a g i s s a i t d ’a p p r é c ie r l a q u a n tité de t e r r e s r a r e s re te n u e d a n s d e s a c ie r s ay a n t re ç u au c o u r s de l e u r fu sio n , un e ad d itio n de la n th a n e p u r ou d e m ic h m e ta l , acco m p ag n ée d an s c e r ta in s c a s d ’a r s e n ic . L e s éc h a n tillo n s & a n a ly se r , con tenan t de 0,01 à 0,5% L a, se p ré se n ta ie n t sous fo rm e de band e s la m in é e s d ’e n v iro n 0,1 m m d ’é p a is s e u r . On a a d m is que l a p ro p o rtio n de lan th an e , p a r ra p p o r t à l ’en sem b le d es a u tre s t e r r e s r a r e s du m ichm eta l, n ’é ta i t p a s m od ifiée p a r l ’in tro d u c tio n de ce p rodu it dans l ’a c ie r .

C a ra c té r is t iq u e s ra d io a c tiv e s d es éch an tillo n s i r r a d ié s

L e s c a r a c té r is t iq u e s d es rad io é lé m e n ts su sc e p tib le s de se fo rm e r dans l e s é c h a n t illo n s d ’a c ie r é tu d ié s à la s u ite d ’un e i r r a d ia t io n d e 1 s e m a in e d a n s un flux de n e u tro n s de 1 0 12 n e u tro n s /c m 2 - s so n t le s s u iv a n te s ,r e p r o d u i te s au ta b le a u II.

TABLEAU П

CA R A C TÉR ISTIQ U ES DE QU ELQ U ES RADIOELEM ENTS

Radio-

isotope Période

Energie des principaux rayons y

(MeV)

Activitéspécifique

(m e)

59 Fe 45 j 1,10 1,29 0,08

143 C e 33,4 h 0,29 0,49 0,70 0,89 1,10 11

141 Ce 32,5 j 0,14 3.7

140 La 40 h 0,33 0.49 0,81 1,6 2,5 880

W As 26 h 0,56 0,21 2,09 (faible) 1200

56 Mn 2,6 h 0,84 1,81 2,13 3900

L ’ex a m e n de ce ta b le a u m o n tre :a) L e la n th a n e -1 4 0 (Tj ̂ = 40 h) e t l ’a r s e n ic - 7 6 (T* = 26 h) o n t à la f in de

l ’i r r a d ia t io n d e s a c tiv i té s sp é c if iq u e s e n v iro n 1 0 0 0 0 fo is p lu s g ra n d e s que c e l le s du f e r . Aux te n e u rs c o n s id é ré e s , c e s a c tiv ité s son t p a r co n sé q u en t au m o in s du m êm e o rd re de g ran d e u r que c e lle du f e r de l ’éc h an til lo n .

b) L e c é r iu m s ’ac tiv e en donnant n a issan c e au 141Ce (T$ = 32,5 j) qui n ’ém et q u ’u n ra y o n n e m e n t y t r è s m o u (0 ,14 M eV), e t du i43Ce (T^ = 33 ,4 h ). D an s un m ic h m e ta l , où le c é r iu m a une te n e u r en v iro n double de c e lle du la n th an e , l ’a c tiv i té du 140L a e s t env iron 40 fo is p lu s é lev ée que ce lle du i43C e. On p eu t donc c o n s id é r e r l ’a c tiv i té du c é r iu m co m m e t r è s fa ib le p a r r a p p o r t à c e lle du la n th an e d an s le s jo u r s qui su iv e n t la fin de l ’i r r a d ia t io n .

c) L e m ic h m e ta l c o n t ie n t d ’a u t r e s t e r r e s r a r e s qu i p r é s e n te n t d e t r è s g ra n d e s s e c tio n s e f f ic a c e s d ’a c tiv a tio n p a r le s n e u tro n s . M a is le s t e n e u r s d e c e s é lé m e n ts d a n s le m ic h m e ta l so n t t r o p fa ib le s p o u r q u ’i l s

APPLICATIONS DIVERSES DES RADIOÉLÉMENTS DE COURTE PÉRIODE 301

p u is s e n t p r é s e n te r une a c tiv i té a p p ré c ia b le p a r r a p p o r t à c e lle du la n th a n e -1 4 0 .

d) L a se u le im p u re té de l ’a c ie r qui p ré s e n te une se c tio n e ff ica ce d ’a c tiv a t io n é le v é e e s t le m a n g a n è s e . M a is , c e t é lé m e n t donne n a i s s a n c e au й Мп (T | = 2 ,6 h), dont l ’a c tiv i té d ev ien t p ra tiq u e m e n t n u lle au bout d ’un jo u r .

e) L e la n th a n e -1 4 0 é m e t un s p e c tr e y com plexe c o m p o rta n t n o tam m en t un ray o n n e m en t de 1,6 M eV. Le s p e c tre y de 76As e s t ég a lem en t com plexe . L e s p e c tr e du 56Fe e s t com posé de deux rayonnem en ts de 1,10 e t 1,29 MeV

M éthode d ’a n a ly se

C es c o n s id é ra tio n s m o n tre n t que dans le s é c h an tillo n s ne con tenan t pas d ’a r s e n ic , on p e u t d é t e r m in e r l a t e n e u r en la n th a n e ou en m ic h m e ta l d e s é c h a n tillo n s p a r une s im p le m e s u re du ta u x de co m p tag e du ray o n n e m en t y. I l su ff it de d is p o s e r d ’un a p p a re il m un i d ’un c o m p te u r à s c in ti l la t io n s co n n e c té à un d is c r im in a te u r d ’am p litu d e d e s im p u ls io n s , c e lu i - c i é ta n t ré g lé p o u r d is c r im in e r le s im p u ls io n s d ’é n e rg ie s u p é r ie u r e s k 1,30 MeV; i l c o n v ie n t se u le m e n t de p re n d re la p ré c a u tio n d ’a t te n d re deux jo u r s a p rè s la fin d e l ’i r r a d ia t io n av an t d ’e f fe c tu e r le s m e s u re s , p o u r p e r m e t t r e l a d é c r o is s a n c e du m a n g a n è se -5 6 e t de d is p o s e r le s éc h a n tillo n s en une p o s itio n b ien re p ro d u c tib le p a r ra p p o r t au c o m p te u r .

L o rs q u e le ta u x de co m p tag e de l ’a c tiv i té du la n th a n e m e s u ré avec un s e u i l d e d is c r im in a t io n d e 1,30 M eV e s t fa ib le , on p eu t a u g m e n te r l a p r é c is io n de la m e s u re en e ffec tu an t d e s co m p tag es avec un se u il de d i s c r im in a tio n p lu s b a s . M a is , d an s ce c a s , on m e s u re une c e r ta in e f ra c tio n du r a y o n n em en t é m is p a r le f e r - 59; on p eu t f a c ile m e n t en t e n i r co m p te en m e s u ra n t d an s le s m ê m e s c o n d itio n s de ré g la g e é le c tro n iq u e e t g é o m é tr iq u e , l e ta u x d e co m p tag e d ’un é ta lo n d e f e r p u r i r r a d ié en m ê m e te m p s que le s é c h a n t i l lo n s .

P o u rv u que le s e u i l d e d is c r im in a tio n c h o is i ne s o i t p a s tro p b a s , le s e f fe ts d ’a u to -a b s o rp tio n p eu v en t ê t r e n é g lig é s , e t on p eu t fa c ile m e n t co m p a r e r le s ta u x de co m p tag e m e s u ré s , en a d m e tta n t qu’i l s so n t p ro p o r tio n n e ls aux p o id s d e s é c h a n tillo n s e t d e s é ta lo n s .

P o u r e s t im e r l a te n e u r en la n th a n e d e s é c h a n ti l lo n s , on a v a it u t i l i s é un é ta lo n p r é p a r é en a c tiv a n t un e p e t i te q u a n tité de la n th a n e p ra tiq u e m e n t p u r que l ’on av a it d is so u te e n su ite p a r a ttaq u e ac ide ; a p rè s d ilu tion e t p r is e d ’une p a r t i e a liq u o te , le la n th a n e a v a it é té p r é c ip i té \ l ’é ta t d ’o x a la te p a r ad d itio n p r o g r e s s iv e d ’am m o n iaq u e , su iv a n t une m é th o d e g é n é ra le de p r é c ip ita t io n d e s t e r r e s r a r e s . P o u r l e s a u t r e s s é r i e s d e m e s u r e s , i l a é té ju g é p lu s co m m o d e d ’u t i l i s e r co m m e é ta lo n un é c h a n tillo n f e r - la n th a n e , ci te n e u r en la n th a n e du m ê m e o r d r e de g ra n d e u r que ceux d e s éc h a n tillo n s \ d o s e r , m e s u ré e lo r s de c e tte p r e m iè r e d é te rm in a tio n .

L a p r é s e n c e d ’a r s e n ic d a n s l ’é c h a n t i l lo n p e u t in t r o d u i r e un e lé g è r e e r r e u r d a n s l ’a p p ré c ia tio n de la te n e u r en la n th a n e . E n e ffe t, le s p e c tr e y d e l ’a r s e n ic c o m p re n d , o u tre d iv e r s ra y o n n e m e n ts d ’é n e rg ie in f é r ie u re "à 1,30 M eV, un ray o n n e m en t peu in te n se d ’é n e rg ie 2,04 MeV (ce tte e r r e u r ne d é p a s s e p a s 5% lo r s q u e le s te n e u r s en a r s e n ic e t la n th a n e so n t du m ê m e o r d re d e g r a n d e u r ) . M a is , on p eu t e f fe c tu e r s im p le m e n t la s é p a ra tio n c h im ique d e s t e r r e s r a r e s e t de l ’a rse n ic .O n p ré c ip ite d ’abord le s t e r r e s r a r e s

302 A. KOHN

so u s fo rm e d ’o xala te , en ajou tan t de l ’ac ide oxalique e t un e n tra în e u r conven ab le (su lfa te c é r iq u e p a r exem ple) à la so lu tion d ’attaque , p u is en am enan t c e t te s o lu tio n au pH=2 p a r a d d itio n d ’a m m o n ia q u e . L e f e r c o m p le x é p a r l ’a c id e o x a liq u e r e s t e en so lu tio n a in s i que l ’a r s e n ic . A p rè s f i l t r a t io n , on r é a c id if ie le f i l t r a t p a r l ’ac id e su lfu riq u e , a jou te du su lf ite de sod ium p o u r r é d u i r e le f e r à l ’é ta t f e r r e u x , a jo u te l ’e n t r a în e u r ( s e l d e m o ly b d è n e p a r ex em p le ) e t p r é c ip i te l ’a r s e n ic à l ’é ta t de su lfu re p a r l ’an h y d rid e su lfhyd - r iq u e .

L a m e s u re d e s ta u x de com ptage d e s p ré c ip ité s d ’o x a la te e t de su lfu re , e f fe c tu é e en c o m p a ra is o n av e c d e s p r é c ip i t é s - é ta lo n s p r é p a r é s d a n s d e s con d itio n s an a lo g u es, p e rm e t de d é te rm in e r a isé m e n t le s te n e u rs en t e r r e s r a r e s e t en a r s e n ic du m é ta l . C om m e le s p r é c ip i té s so n t e x e m p ts de f e r , on peu t e f fe c tu e r le s m e s u re s avec un b a s se u il de d is c r im in a tio n . D ans ce c a s , on p eu t é g a le m e n t a p p r é c ie r s é p a ré m e n t le s te n e u r s en lan th an e e t en c é r iu m , en effec tuan t le s m e s u re s s u r le s échan tillons et s u r des p ré c ip ité s - é ta lo n s avec deux s e u i ls de d is c r im in a tio n , l ’un a s s e z b a s , qui p e rm e t de c o m p te r à la fo is le c é riu m e t le lan thane , l ’a u tre v e r s 1,2 MeV qui ne la is s e p a s s e r que le rayonnem en t du lan thane .

CONCLUSIONS

C et ex p o sé , se p ro p o s a i t de m o n t r e r co m m en t l ’e m p lo i de te c h n iq u e s ra d io a c tiv e s , e t p lu s p a r tic u liè re m e n t de m éthodes fa isa n t appel à d es rad io é lé m e n ts d e p é r io d e s r e la t iv e m e n t c o u r te s , a v a ie n t p e r m is d e r é s o u d r e d iv e r s p ro b lè m e s de c a r a c t è r e m é ta llu rg iq u e , e t de m e t t r e en ev id en ce la t r è s g ra n d e d iv e r s i té de l e u r s co n d itio n s d ’u ti l is a t io n .

D ’un cô té , la te ch n iq u e au to ra d io g ra p h iq u e , d ’un em p lo i beaucoup p lu s com m ode lo r s q u ’e l le s ’app lique 'k d e s é c h an tillo n s a c tiv é s , p r é p a ré s p r é a la b le m e n t ci l ’é ta t in a c ti f , a p e r m is de m e t t r e t r è s n e t te m e n t en é v id e n c e c e r ta in s p h én o m èn e s p a r t i c u l i e r s co m m e l ’e n r ic h is s e m e n t e n a r s e n ic d e s é c h a n tillo n s d ’a l lia g e de f e r oxydé, ou l a p r o g re s s io n de c r is ta u x p a u v re s en c u iv re au c o u rs d e l a s o lid if ic a tio n d ’a llia g e a lu m in iu m - c u iv re .

D’a u tre p a r t , la s im p lic ité de c e r ta in e s m é th o d es d ’an a ly se p a r a c tiv a tio n p o r ta n t s u r l e s é c h a n t illo n s b r u ts ou ne n é c e s s i ta n t que d e s p r é p a r a tio n s ch im iq u e s t r è s s im p le s , év ite d ’a v o ir à m e t t r e au po in t d es m éth o d es a n a ly tiq u es p lu s c la s s iq u e s , m a is p lu s d é l ic a te s à m e t t r e en oeuvre.

L a s e n s ib il i té de l ’a n a ly se p a r ac tiv a tio n , d é jà souven t sou lig n ée l o r s q u ’i l s ’a g is s a i t de d o s e r d e s t r a c e s d ’im p u re té s d an s un m é ta l , e s t é g a le m e n t p a r t ic u l iè r e m e n t a v a n ta g e u se lo r s q u ’i l s 'a g i t de d o s e r d e s q u a n tité s p lu s im p o r ta n te s m a is d an s d es p ré lè v e m e n ts e x trê m e n t m in im e s .

E n fin , d a n s un a u t r e o r d r e d ’id é e to ta le m e n t d if fé re n t, l ’e m p lo i d ’un é lé m e n t à fa ib le p é r io d e e t à ray o n n em en t y m oyen , com m e P o r-1 4 8 , s ’e s t r é v é lé p a r t i c u l iè r e m e n t a v a n ta g eu x p o u r d e s é tu d e s in d u s t r ie l le s p o r ta n t s u r d e s q u a n tité s de m a t iè r e de p lu s ie u r s to n n e s . L e ray o n n e m en t y é m is p a r c e t é lém e n t e s t en effe t a s s e z p é n é tra n t p o u r p o uvo ir p e rm e ttr e d ’e f fe c t u e r d e s m e s u r e s a v e c un e p r é c is io n s u f f is a n te à l ’a id e d ’u n c o m p te u r à s c in t i l la t io n s . L a p é r io d e de 60 h de c e ra d io iso to p e , su ff isa m m e n t longue p o u r p e r m e t t r e de r é a l i s e r c o r re c te m e n t l ’en se m b le d e s o p é ra tio n s in d u st r i e l l e s e n v is a g é e s , e s t c e p en d a n t su ff is a m m e n t c o u r te p o u r que l ’a c tiv ité


d is p a r a is s e a s s e z ra p id e m e n t p a r d é c ro is s a n c e n a tu re lle , év itan t a in s i tou t r is q u e de co n tam in a tio n p a r le m é ta l a in s i m a rq u é ou to u t in co n v én ien t qui p o u r ra i t r é s u l t e r de l ’u til is a tio n de p ro d u its fa b r iq u é s à p a r t i r de ce m é ta l .


[1] KOHN, A ., Quelques applications de l'u tilisation des radioéléments dans l'analyse des métaux, Communication présentée au XXXIIIe Congrès de chimie industrielle, Bordeaux (Octobre 1961) (à paraître prochainement dans Chim ie analytique).

[2] KOHN, A. e t PHILIBERT, J . , Contribution à l 'é tude de la solidification des alliages. M émoires scien tifiques de la Revue de m étallurg ie , 57 4,(1960) 291-312. Publication IRSID n° A-223.

[3] EFIMOV, L .M ., BUL’SKU, M .T ., JAKUSlN, V . I . , ALIMÓV, A. G . , e t SKREBCOV, Etude de la solidification de l 'a c ie r au moyen de radioélém ents. Stal 12 (1955) 1090.

[4] ZBOROVSKU, A. A ., STRELKOV, L. K . , SKUL'SKU.M .K. e t RABINOV1C, E .I. M ouvements de l 'a c ie r liquide en lingotière . S tal 1 (1957) 24.

[5] de BEAULŒU, C . , CAGNET, M. e t MOREAU, J. Etude au moyen des radioindicateurs de l'enrichissem ent en im puretés au cours de l'oxydation des aciers, Mémoires scientifiques de la Revue de m étallu rg ie 57(1960), 863-875, Publication IRSID n° A-243.

[6] VODOPIVEC, F. e t KOHN, Av Etude quantita tive de l'enrichissem ent superficiel en arsenic au cours de l 'oxydation , dans un a lliage de fer fa ib lem ent a llié en ce t é lém en t. C .R . Acad. Sci. 253 (1961) 448.

D I S C U S S I O N

P . C . A EBERSO LD (C h a irm an ): T h is p a p e r h as in d eed d e m o n s tra te dth e v a r ie ty of a p p lica tio n s of ra d io is o to p e s in m e ta l lu rg ic a l s tu d ie s — fro m v e ry sm a ll c r y s ta ls to ingo ts of o v er 60 t . Am I r ig h t in assum ing th a t s ince s h o r t- l iv e d iso to p e s w e re u se d , th e re w as no p ro b le m in pub lic s a le o r u se o f th e p ro d u c ts a f te r s u i ta b le d e c a y p e r io d s ? I b e l ie v e b o th G e rm a n and R u s s ia n w o rk e rs have u se d A u 198 in th e s tudy of s te e l-m a k in g and ingot f o r m a tio n ; how d o es y o u r w ork c o m p a re w ith th e i r s ?

A. KOHN: S ince th e f i r s t t e s t s c a r r ie d out s ix o r se v en y e a r s ago, inw h ich w e u se d r a d io a c t iv e go ld to d e te r m in e th e d e s c e n t t im e s of b l a s t fu rn a c e c h a r g e s ; go ld - 198 h a s b ee n u se d in d u s t r ia l ly in a n u m b e r of count r i e s , p a r t ic u la r ly G erm any and the USSR, to in v e s tig a te v a rio u s phenom ena c o n n e c te d w ith th e m a n iifa c tu re o f s te e l . G o ld -198 i s in fa c t p a r t i c u la r ly a d v a n ta g eo u s fo r th e s e s tu d ie s .

W ith r e g a r d to th e s tu d y of co n v e c tio n c u r r e n ts in s te e l in g o ts , th e r e s u l t s we have ob ta ined a r e s im ila r to th o se of th e R u ss ian e x p e r im e n te rs , though o u r s tu d y r e la te d to m uch l a r g e r ingo ts and th e m e a su r in g techn ique w hich we u se d w as p ro b ab ly m o re a c c u ra te .

A . S E L L E R IO : T h e d a ta p r e s e n te d by M r. K ohn and th e s e r i e s ofph o to g rap h s re p ro d u c e d in F ig . 2 a r e in te re s tin g b ecau se th ey show the s ta r t and d ev e lo p m e n t o f c ry s ta l l i z a t io n , w hich i s a s ta g e in th e t r a n s i t io n f ro m th e d is o r d e r e d s ta te (liquid) to th e o rd e re d s ta te (c ry s ta l l in e ) . I th in k th a t i f th e t im e s and d is ta n c e s w e re know n, one cou ld d e te rm in e a p p ro x im a te ly th e r a t e of p ro p a g a tio n of th e o rg a n iz in g fo rc e s w hich c e r ta in ly e x is t.

A. KOHN: O ur w ork fo rm ed p a r t of a s tudy on so lid ifica tio n phenom ena,w hich a r e now b ein g in v e s tig a te d in v a r io u s c o u n t r ie s . Som e of th e s tu d ie s

304 A. KOHN

c a r r i e d ou t a im a t e s ta b l is h in g th e m e c h a n is m o f s o lid if ic a tio n , i . e . th e n a tu re and a c tio n o f th e fo rc e s g o v e rn in g th e a r r a n g e m e n t o f liq u id a to m s in to an o rg a n iz e d c r y s ta l l in e s t r u c t u r e . H o w ev er, th e s e p h e n o m e n a ta k e p la c e a t th e a to m ic le v e l, and I do no t th in k th a t au to rad io g rap h y could supply any e x a c t q u a n tita tiv e in d ic a tio n s in th is c o n n e c tio n , though i t cou ld p ro b ab ly h e lp in fo rm u la tin g th e n e c e s s a r y h y p o th e se s fo r s tu d y in g th e s e p h e n o m e n a by o th e r te c h n iq u e s .

SEPARATION OF IMPURITIES IN THE ZINC RECTIFICATION PROCESS

BY RADIOACTIVE ISOTOPES

K. AKERMAN, M. BRAFMAN, H. FIK, J. KITALA, M. NOWAK AND A. POCZYNAJLO

INSTITUTE OF NUCLEAR RESEARCH, POLISH ACADEMY OF SCIENCES,WARSAW, POLAND


SEPARATION OF IMPURITIES IN THE ZINC RECTIFICATION PROCESS BY RADIOACTIVE ISOTOPES. The process o f z inc red istilla tion in New Jersey-type columns and its th eo re tic a l princip les, as e labora ted by A. Krupkowski, are briefly described. P ractical conclusions arising from the m athem atica l expression of the process, performed on the basis of the above theory, are sum m arized.

A description is given of experiments on the separation of h igh- and low-boiling-point impurities in zinc and the behaviour of the basic constituent itse lf under norm al working conditions. These experim ents were carried out using radioisotopes CuM and Fe59 (high-boiling-point impurities), Cdli5 (low-boiling-point impurity) and Z n e9/n (basic constituent). The conclusions derived from the experim ental data substantiate the theory of zinc redistillation advanced by A. Krupkowski. Moreover these conclusions allow definite propositions to be m ade concerning some charge in param eters under which the condensation of z inc-cadm ium vapours in the cadm ium colum n is performed. Due to this change recovery of cadm ium from the charged m eta l can be in creased and the quality o f high purity zinc, obtained by redistillation , can be improved.

SEPARATION DES IMPURETÉS, A L'AIDE DE RADIOISOTOPES, DANS L* AFFINAGE DU ZINC PAR VOIE

SECHE. Les auteurs décrivent brièvem ent le procédé de redistillation mis en œuvre dans des colonnes du type New Jersey e t indiquent les principes théoriques, établis par A. Krupkowski, sur lesquels i l se fonde. Ils ré sument brièvement les conclusions pratiques que l*on tire d 'une expression m athématique de l'opération établie sur la base de cette théorie.

Ils décrivent ensuite les expériences de séparation des impuretés à haut point d 'ébullition e t à bas point d 'ébullition auxquelles ils ont procédé e t indiquent le comportement du constituant de base lui-m êm e dans des conditions norm ales. Ces expériences ont é té effectuées à l 'a id e de **Cu e t de s®Fe (im puretés à haut point d 'ébu llition), de 115Cd (im puretés à bas point d 'ébullition) e t de 69nlZn (constituant de base). Les conclusions que l 'o n tire de ces expériences confirm ent la théorie élaborée par A. Krupkowski. Elles perm ettent en outre de formuler des propositions concrètes concernant une m odification à apporter aux param ètres qui traduisent les conditions dans lesquelles s'effectue la condensation des vapeurs zinc-cadm ium dans la colonne cadm ium. Grace à cette m odification, on peut augm enter la récupération de cadm ium provenant du m étal prim itif, et am éliorer la qualité du zinc de grande purete obtenue par redistillation.

ОТДЕЛЕНИЕ ПРИМЕСЕЙ В ПРОЦЕССЕ РЕКТИФИКАЦИИ ЦИНКА С ПРИМЕНЕНИЕМ РАДИОАКТИВНЫХ РАДИОИЗОТОПОВ. В работе коротко описан процесс ректификации цинка в колоннах типа Нью-Джерси и теоретические основы этого процесса, разработанные А. Крупкоаским. Приведены также практические выводы, которые являются результатом математического исследования процесса ректификации с точки зрения этой теории.

В работе описаны опыты по исследованию процесса ректификации цинка, в которых были применены радиоактивные изотопы. Исследовалось отделение примесей, обладающих высокой и низкой температурой кипения, а также поведение основной составляющей, то-есть цинка, во время нормальной работы колонны.

В опытах были применены следующие радиоактивные изотопы: Cu04,Fe98 (высококипящие примеси), Cdlls (примесь с низкой температурой кипения) и Zneem (оснавная составляющая). Результаты проведенных исследований являются опытным подтверждением теории А. Крупковского. ■

305

306 К. A KERMAN et aL

Полученные данные указывают на целесообразность изменения параметров конденсации паров цинка и кадмия в кадмиевой колонне для того» чтобы увеличить извлечение кадмия из исходного металла и повысить качество цинка, получаемого в результате ректификации.

ESTUDIO MEDIANTE RADIOISOTOPOS DE LA SEPARACIÓN DE IMPUREZAS EN EL PROCESO DE PURIFICACION DEL CINC. En la m em oria la separación de im purezas en e l proceso de purificación d e l cinc se estudia con ayuda de radioisótopos. Se describen brevemente e l proceso de redestilación del cinc en columnas de l tipo New Jersey y sus principios teóricos, establecidos por A. Krupkowski. Se resum en las conclusiones prácticas que se desprenden de la expresión m atem ática del proceso, obtenida basándose en la teoría m encio- nada.

Se describen asim ism o los experim entos de separación de impurezas de a lto y bajo punto de ebullición presentes en e l cinc y e l com portam iento del propio componente básico e n condiciones norm ales de trabajo. Estos experim entos se llevaron a cabo u tilizando los radioisótopos e*cu y ®Fe (im pureza de a lto punto de ebullición), u s e d (im pureza de bajo punto de ebullic ión) y ®*m Z n (com ponente básico). Las conclusiones extraídas de los datos experim entales corroboran la teoría de la redestilación d e l c inc , e laborada porA. KrupkowskL Además, estas conclusiones perm iten definir las propuestas que cabe form ular con respecto a cambios en los parámetros con arreglo a los cuales la condensación de los vapores de cinc-cadm io se efectúa en la colum na del cadm io. Estos cam bios perm iten aum entar la recuperación de cadm io de l m eta l cargado y m ejorar la calidad d e l cinc de a lta pureza, obtenido por redestilación.

THEORY AND PRACTICE OF THE REFINING PROCESS OF ZINC

Z in c i s on e o f th e e s s e n t i a l m a jo r n o n - f e r r o u s m e ta l s n e c e s s a r y to in d u s t r ia l eco n o m y , and m o d e rn te c h n iq u e c a l ls fo r h ig h p u r i ty . Z in c r e f in in g i s a c h ie v e d w ith r e f in in g f u rn a c e s an d r e d i s t i l l a t io n in r e f in in g co lu m n s. R efin ing by liq u a tio n is ap p licab le when le a d and iro n a re involved.

Z in c of 99.99% p u r i ty ca n be o b ta in ed by r e d is t i l la t io n in New J e r s e y - type re c tify in g co lu m n s. Z inc of 99. 999% p u rity , can be ob ta ined by vacuum d is t i l la t io n an d c o n d e n sa tio n o f th e z in c v a p o u r s in g r a p h ite r e t o r t s .

In P o la n d a m e th o d fo r re f in in g z in c by r e d is t i l l a t io n in N ew J e r s e y - type re c tify in g co lum ns is w idely u se d and the co lum ns a r e ex p o rted to m any c o u n tr ie s in E u ro p e and A sia .

P r in c ip le s o f th e p r o c e s s e s an d d e s c r ip t io n s o f co lu m n c o n s t ru c t io n and o p e ra tio n techno logy a r e to be found in the l i t e r a tu r e [1-8] . In [8] p ro b le m s in z in c - re f in in g a r e t r e a te d . F o r th is r e a s o n we p ré s e n t h e re only the re f in in g m ethod ( F ig . l ) u se d fo r h ig h -p u ri ty z inc p ro d u c tio n .

T he so le a t te m p t m ade to date to e lu c id a te the p ro c e s s of z inc r e d is t i l la t io n by th e N ew J e r s e y m e th o d , and to c r e a te an a p p ro p r ia te th e o re t ic a l b a s is (e x p re s se d in m a th e m a tic a l eq ua tions) w hich m ig h t allow the fin a l r e s u l t s o f r e d i s t i l l a t io n f ro m o p e ra t io n a l c o n d itio n s to be f o r e s e e n , i s th a t o f KRU PK O W SK I [3, 8 , 9] .

KRUPKOW SKI and F IK [8] have m ad e the h e a t and m a te r ia l b a lan c e of th e r e d is t i l la t io n p r o c e s s u n d e r ro u tin e co n d itio n s . T hey d is c u s s th e th e o r e t i c a l p r in c ip le s o f d is t i l la t io n u n d e r in d u s t r ia l c o n d itio n s and c a lc u la te v a p o u r p r e s s u r e s fo r z in c , c a d m iu m and le a d , d is t i l la t io n c u r v e s of th e z in c - le a d s y s te m a t te m p e ra tu re s ap p ro ach in g th e bo iling poin t of z inc , d is til la t io n c u rv e s of the zinc cadm ium s y s te m and th e ir d is t illa tio n co e ffic ien ts . On th is b a s is th e y c a r r i e d out c a lc u la tio n s of the r e d is t i l la t io n p r o c e s s fo r co n s ta n t d is t i l la tio n and cond en sa tio n co e ffic ien ts and when th e se co effic ien ts w e re v a r ia b le , a c c o u n t w as ta k e n of th e c o n c e n tra t io n in s o lu t io n an d of te m p e r a tu r e .

SEPARATION OF IMPURITIES IN ZINC RECTIFICATION PROCESS 307

Fig. 1

Apparatus for refining zinc by fractional distillation1 - m elting furnace2 - lead column3 - condenser4 - cadmium column5 - cadm ium canister6 ■ refined -m etal pot7 - liquating pot

T h e m a in c o n c lu s io n s a r i s in g f ro m th is w o rk a r e :1. In th e r e d is t i l l a t io n of z in c on ly d is t i l la t io n and d ep h leg m a tio n a r e

ap p lie d . H o w ev er, th e m o s t e f fe c tiv e f a c to r of th e p r o c e s s , r e d is t i l l a t io n u n d e r a s ta te o f fu ll e q u i l ib r iu m , i s n o t ap p lied .

2. T o c a lc u la te th e c o m p o s itio n of v a p o u rs o rig in a tin g f ro m a d e fin ite so lu tio n in th e re c tify in g co lu m n s, K rupkow sk i a s su m e d an independen t d is c h a rg e of th e v a p o u rs f ro m e a c h t r a y to th e o u ts id e , a l l o th e r t r a y s b e in g o m itte d . T h u s th e liq u id f ro m th e in d iv id u a l t r a y is in e q u i lib r iu m w ith i t s ow n v a p o u rs on ly . T h is in te r p r e ta t io n in v o lv e s th e a s s u m p tio n of th e s o - c a lle d " p a ra l le l s t r e a m s " w hich a r e p re se n te d g ra p h ic a lly in F ig . 2. R e su lts f ro m th e above d ia g ra m , w h ich d e m o n s tr a te s th e w o rk of th e re c tify in g co lum n , d iv ided in to e le m e n ts of the w ork ing in te n s ity , a r e show n in F ig . 3.

3. On th e b a s i s o f c a lc u la t io n s on th e d is t i l la t io n and d e p h le g m a tio n p r o c e s s in th e le a d co lu m n , i t fo llo w s th a t:

(a) In c re a s e to m a x im u m in th e z inc v a p o r iz a tio n in te n s ity (P4) r e s u l t s in in c re a s in g c o n c e n tra tio n of th e h ig h -b o ilin g -p o in t m e ta l s in a l l th e e le m e n ts o f th e w o rk in g in te n s i ty of th e co lu m n .

(b) In c re a s e in d ep h leg m atio n in te n s ity (P2) fav o u rab ly a ffec ts th e conc e n tra t io n of le a d in th e c o n d e n se r .

(c) In re f in in g p ra c t ic e a com b in atio n of the above p o s tu la te s is app lied ,i. e . , in c re a s in g in te n s if ic a tio n in z inc v a p o riz a tio n (P4) in o rd e r to d e c re a s e

308 K. AKERMAN et al.

4POURS

ONDENSATES

Fig. 2

Diagram showing the principle of "parallel streams"Parallel streams of vapour evaporating from trays in boiler are directed out of the column and then to the

condenser without passing through the other trays.

Working principle of the reflux column.Pj = charge, P2 = amount of condensed m etal (cooling capacity of column), P4 = amount of evaporated m etal (heating capacity), P, = P, + P2 - P4 = condensates flowing to sump, P5 = P4 - P, = vapour passing to condenser.

1 -feed inlet, 2 -bo iler, 3 -dephlegm ator, 4 -condenser.


th e am o u n t o f z in c B *, is fo llow ed by in te n s if ie d d e p h leg m a tio n , in o r d e r to p re v e n t d e te r io r a t io n of th e q u a lity of NO z in c * * .

(d) I n c r e a s e in th e c h a rg e (P i) and in the in te n s ity of v a p o r iz a tio n (P4 ) fa v o u ra b ly a f fe c ts th e d is t i l la t io n of c a d m iu m in th e c o lu m n , b e c a u s e th e q u a l i ty o f z in c is im p ro v e d w hen th e o u tp u t in c r e a s e s (P5).

4. F r o m c a lc u la t io n of th e d is t i l l a t io n an d d e p h le g m a tio n c o u r s e in th e c a d m iu m co lu m n i t fo llo w s th a t:

(a) The p ro d u c ts en te r in g the cadm ium colum n con tain only in sig n ifican t am oun ts of le ad , but the c o n c e n tra tio n of cadm ium in the p ro d u c ts is g r e a te r th an in the le a d co lum n.

(b) I n c r e a s e in th e v a p o r iz a t io n in te n s i ty (P 4 ) fa v o u ra b ly a f f e c ts th e q u a lity of NO z in c (the c o n te n t of c a d m iu m d e c r e a s e s ) , b u t d e c r e a s e s th e o u tp u t (P 3).

(c) I n c r e a s e in th e c o n d e n s a tio n in te n s i ty (P 2) r e s u l t s in in c r e a s in g c o n c e n t r a t io n of c a d m iu m in th e e le m e n ts o f th e w o rk in g in te n s i ty o f th e co lu m n .

5. On th e b a s is of th e m a te r ia l b a la n c e , m ad e a f te r a n a ly s e s of w ork co n d itio n s , i t w as found th a t th e le a d c o n c e n tra tio n in the v a p o u rs e sca p in g f ro m th e le a d c o lu m n ( P 5) i s c o n s id e r a b ly h ig h e r th a n i s in d ic a te d by th e c a lc u la t io n s d is c u s s e d above (p a ra . 3). A n a ly s is of th is fa c t le a d s to a co n c lu s io n th a t th e z in c v a p o u rs e n te r in g th e d e p h le g m a to r a r e p a r t i a l ly co n d en sed in i t , fo rm in g a z in c - le a d m is t due to co n d en sa tio n . The ac tu a l r a te of v a p o u rs in th e d e p h le g m a to r v a r ie s b e tw een 8 m / s in th e lo w e r p a r t and 1.5 m / s , w hen e n te r in g th e c o n d e n s e r . P a r t of th e m is t p r e c ip i ta te s in to th e dow n-flow ing liq u id , and a n o th e r p a r t i s t r a n s p o r te d in to the c o n d e n se r by the ra p id ly ascen d in g v a p o u rs . T he la r g e r d ro p le ts a r e p re c ip ita te d e a s ily , w h e re a s th e s m a l le r o n es a r e su sp e n d e d in z in c v a p o u rs . T he s iz e of th e t r a n s p o r te d m is t d ro p le ts in c r e a s e s b e c a u s e , w hile r i s in g to the u p p e r t r a y s , th e y b e c o m e new c e n t r e s o f c o n d e n s a tio n fo r o th e r d r o p le t s . T h e d ro p le ts f ro m the u p p e r t r a y s of the d ep h leg m a to r do no t grow as e ffic ien tly a s th e d ro p le ts f ro m th e lo w e r t r a y s : th e re fo r e the am oun t of m is t p a s s in g to the co n d e n se r fro m the fo rm e r t r a y s is m uch la rg e r . C alcu la tions indicate th a t p r a c t ic a l ly a l l th e le a d is co n d e n se d on th e fo u r th t r a y of the d ep h leg m a to r . F ro m th is i t fo llow s th a t a lm o s t a l l th e le a d in NO z in c g e ts to th e co n d e n se r by p ass in g the m is ts f ro m th e lo w er se c tio n s of the deph legm ato r. P r a c t i c a l a t te m p ts to re m o v e the in su la tio n of th e lo w e r se c tio n of the d e p h le g m a to r r e s u l t e d in a c o n s id e ra b le d e c r e a s e in th e c o n c e n tra t io n of le a d in NO z in c . T h is is u n d e rs ta n d a b le , s in c e in te n se c o n d e n sa tio n of the v ap o u rs in the lo w e r se c tio n of the d ep h leg m ato r allow s the d ro p le ts of m is t, w hile r i s in g to the u p p e r se c tio n of the co lum n, to in c re a s e th e ir d im ension to su c h an e x te n t th a t a s ig n if ic a n t ly lo w e r p e rc e n ta g è of th e m e n te r the c o n d e n s e r . T h e am o u n t o f t r a n s p o r te d m is t and , a t th e s a m e t im e th e am o u n t o f le a d t r a n s p o r te d to th e c o n d e n s e r , is l a r g e r th e g r e a te r th e v e lo c ity of the v ap o u r in the lo w e r se c tio n of the d ep h leg m ato r and the g r e a te r the co n d en sa tio n of v a p o u rs .

* Zinc В indicates zinc containing h igh -bo iling-po in t im purities.* * NO zinc indicates zinc of h igh purity produced in New Jersey-type rectificá tion columns.

310 К. AKERMAN et al.

C ru d e z in c u s e d a s a c h a r g e fo r r e c t i f y in g c o lu m n s m a y c o n ta in th e fo llow ing m e ta l l ic im p u r i t ie s : P b , C d, F e , C u, Sn, A s, Sb and Ag. A s an e x a m p le th e r e s u l t s o f a c e r ta in c h a rg e d z in c a n a ly s is [8] m a y b e quo ted :

P b - 1.307%C d - 0.506%F e - 0.014%

o th e r e le m e n ts - 0.006% .

T ak in g in to a c co u n t the c o u r s e and th e o ry o f th e p r o c e s s in v e s tig a te d , a s w e ll a s th e co n ten t of p a r t i c u la r a d m ix tu re s in th e c h a rg e , a ch o ice w as m ad e of r a d io is o to p e s a p p ro p r ia te fo r the co lu m n s in q u es tio n . S ince d iffic u l t ie s w e re e n c o u n te re d in ob ta in ing a su ita b le ra d io iso to p e of le a d , s e p a r a tio n of h ig h -b o ilin g -p o in t im p u r i t ie s w as t r a c e d by m e an s of ra d io iso to p e s Fe59 and Cu64.

A lthough F e 5 9 h as qu ite a lo n g h a l f - l i f e , i t w as n e c e s s a r y to u s e i t fo r exam ina tion of the r e s u l t s ob ta ined w ith C u 6 4 , because the u se of rad iocopper of h igh ac tiv ity ( s e v e ra l c u r ie s ) due to lo w -g am m a effic iency , c re a te d m an ip u la tio n and t r a n s p o r t d if f ic u lt ie s u n d e r in d u s t r ia l c o n d itio n s . A m ong the lo w -b o ilin g -p o in t im p u r i t ie s in c ru d e z in c th e m o s t im p o r ta n t is cad m iu m . The l a t te r shou ld be t r e a te d no t a s an im p u rity but as a valuab le b y -p ro d u c t. T he beh av io u r of cadm ium in re d is t i l la t io n p ro d u c ts w as exam ined by m eans o f C d 115. T he s e p a ra t io n of z in c in p a r t i c u la r s e c tio n s of th e c o lu m n s w as exam ined by m ean s of Zn69m. The c o n c en tra tio n s of the ind iv idual adm ix tu res in th e NO z in c p ro d u c e d , w hen p ro d u c tio n w as e x a m in e d b y m e a n s of th e above r a d io is o to p e s , a r e

P b . 0 .0 0 2 5 - 0 .005 %C d . 0 .0 0 1 4 - 0.0035%F e 0 .0 0 0 4 - 0.0007% .

T h e b e h a v io u r o f a l l th e r a d io is o to p e s c h o se n ( ra d io is o to p e s of h ig h - b o ilin g -p o in t m e ta l s , lo w -b o il in g -p o in t m e ta ls an d th e b a s ic c o n s ti tu e n t) w as exam ined in the le a d co lum n. T hen in the cadm ium colum n the behaviour of ra d io a c tiv e cadm ium (low -bo iling -po in t ad m ix tu re ) and of ra d io a c tiv e zinc (b asic co n s titu en t) w as exam ined .

T h e g a m m a a c tiv i ty due to th e r a d io is o to p e s u s e d w as m e a s u r e d w ith a s c in t i l la t io n c o u n te r w ith a th a liu m -a c tiv a te d N al c r y s ta l (3 0 -m m d ia m . , 1 0 -m m h t.) , eq u ip p ed w ith a 1 3 -s ta g e p h o to m u ltip lie r of th e F E U -1 9 ty p e , m ade in th e USSR. T h e se c o u n te rs w ere about five tim e s m o re effec tive thanG -M tu b e s . D u rin g m e a s u re m e n ts the c o u n te rs w e re lo c a te d a t the e x te rn a l

EXPERIM ENTAL*

* In the radioisotope m easurem ents, besides the authors of the paper, the following partic ipan ts also

took part: K. Kruszewski, A. M asiak and J. O giaza - a l l from D epartm ent XVI o f the Institute o f N uclear Research; members of the Post-graduate Course in the Field of Nuclear Chemistry-, S. Folek from the Institute of Inorganic Chem istry and L. Kornblit from the Central Laboratory of Petroleum Technology; S. Gotebiowski,B. Nowotnik and J. S taw ierej, techn icians from D epartm ent XVI of the Institute o f N uclear Research.


w a lls of e a c h co lu m n in v e s tig a te d a t d if fe re n t p o in ts of th e d e p h le g m a to rs , c o n d e n s e rs and o v e r th e su m p s . T o p r o te c t th e c o u n te r s a g a in s t th e h igh te m p e r a tu re of th e co lu m n s th ey w e re p la c e d in s id e m e ta l l ic w a te r c o o le r s so th a t th e ir te m p e ra tu re did no t ex ceed 20°C. T he co u n te rs w ere connected w ith in teg ra tion , sy s te m s of the RU S-4 ty p e , m ade in P o land .

T o m e a s u r e th e a c tiv i ty p a s s in g th ro u g h th is s e c tio n o f th e r e c tify in g co lu m n w hich is in th e f ir e - c h a m b e r (b o ile r) , two G -M -c o u n te r tu b e s of the S T S -5 type , connected to an in te g ra tin g re c o rd in g sy s te m , w ere u se d . T h ese G -M c o u n te r s w e re e x p o se d to v e r y h ig h t e m p e r a t u r e s , e x is t in g in tire f i r e c h a m b e rs of th e c o lu m n s . T h ey w e re th e re fo r e e n c a s e d in w e ll - in s u la te d , m e ta l l ic c o o le r s , in tro d u c e d in to th e in s id e of th e f i r e c h a m b e rs , so th a t th e c o u n te rs cou ld f i t t ig h tly to the o u ts id e c a rb o ru n d u m w a lls of th e r e c t i fy ing c o lu m n s . W ith th is p r o te c t io n th e te m p e r a tu r e of th e G -M tu b e s d id n o t e x c e e d 30°C. T h e d is t r ib u t io n of a l l m e a s u r in g p o s it io n s is p r e s e n te d

TABLE I

CH A RA CTER ISTIC S AND A C TIV ITY O F RADIOISOTOPES USED

No. Radioisotope

Energy of y -radiation

(MeV)

Ratio of у -quanta to

number of decayed

nuclei

№

H alf-life

A ctivity of individual samples when introduced into column

(me)

Lead column Cadm ium column

1 2 3 1 2

1_ 69m Zn 0 .44 94 14 h 84 59 _ 120 285_ 65 Zn 1. 12 45 245 d 30 22 - 55 73

Л152 Cd 0. 49 12

0. 52 25 2 .3 d 115 148 - 1390 1560

0 .34 50,115m

Cd 0.49 0 .3 43 d 1.7 3. 2 " 18 27

0. 94 2. 3

1.30 1

3 „ 59 Fe 0. 19 2 .8

1. 10 57 45. Id 18.5 18. 5 13 - -

1. 29 43

- 55 Fe - - EC 2.9 yr 47 47 34 - -

4 ^ 64 Cu 1.34 0 .5 12. 8 h 5070 5070 - - -


in th e f ig u re s , i l lu s t r a t in g th e a c tiv ity a s a fu n c tio n of t im e fo r p a r t i c u la r p o in ts o f the co lu m n . T he a c t iv i t ie s o f th e ra d io is o to p e s w e re s e le c te d fo r tw o a im s to g iv e a n u m b e r of c o u n ts e x c e e d in g ab o u t te n t im e s th e b a c k ground of the c o u n te rs , and to ge t d ilu tion of the a c tiv ity in the end p ro d u cts of the co lum ns su c h th a t th e re w as no h e a lth h a z a rd .

T ak in g in to acco u n t the d if fe re n c e s in th e a b so rp tio n of th e g am m a a c tiv i ty by the c o n s tru c tio n m a te r ia ls of th e co lum n (v ary in g fo r d if fe re n t m e a s u r in g p o in ts ) , v a r io u s d e te c tio n e f f ic ie n c ie s , c a u s e d by th e n e e d to ap p ly c o u n te r s of d if fe re n t c a p a c ity , a s w e ll a s th e d if fe re n c e s in th e geo m e t r y o f m e a s u r e m e n ts , th e f in a l r e s u l t é a r e c o n s id e r e d a s q u a l i ta t iv e . D e sp ite th e se d isa d v a n ta g e s th e r e s u l t s su ff ic ie n tly i l lu s t r a te the c o u rse of the p r o c e s s .

T h e c h a r a c t e r i s t i c s of th e r a d io is o to p e s ap p lied and th e a c tiv ity of the s a m p le s in tro d u c e d w ith a s t r e a m of m e ta l lic z inc in to the co lum ns in v e s tig a ted , a r e p re s e n te d in T ab le I.

T he ra d io iso to p e s p re s e n te d in th is T ab le w ere o b ta in ed by ir ra d ia t io n o f su ita b le m e ta l l ic ta r g e ts in th e EW A r e a c to r . B e s id e s the ra d io iso to p e s , Zn69m , C d i is , Fe59 and Cu64, w h ich a r e p ro d u c e d by th e (n, y) r e a c t io n , o th e r r a d io is o to p e s of z in c , ca d m iu m , i r o n and c o p p e r a r e a ls o p ro d u ce d . H o w ev er, on ly ZnS5 and C d 115, b e c a u s e of th e i r s u ita b le h a l f - l i f e and type o f r a d ia tio n , w e re th e m o s t u se fu l fo r o u r m e a s u re m e n ts . T he a c tiv ity due to lo n g - l iv e d F e 55 co u ld n o t b e m e a s u r e d b e c a u s e th e e n e rg y of r a d ia t io n due to e l e c t r o n c a p tu r e w a s to o w eak . S h o r t - l iv e d Cu66 ( T j = 5 m in ) w as

Fig. 4

Activity curves due to radioactive zinc in lead column


Fig. 5

Activity curves due to radioactive copper in lead column

Fig. 6

Activity curves due to radioactive iron in lead column


Fig. 7

Activity curves due to radioactive cadmium in lead column

Fig. 8

Activity curves due to radioactive zinc in cadmium column


Fig. 9

Activity curves due to radioactive cadm ium in cadmium column

in a p p lic a b le , a s i t d e c a y s d u rin g r e a c to r coo ling . T he r e s u l t s of m e a s u r e m e n ts a r e p re s e n te d in F ig s 4 -9 . T he a c tiv ity of the ra d io iso to p e s u se d fo r in d iv id u a l m e a s u r e m e n ts in th e co lu m n i s p lo tte d a s a fu n c tio n o f t im e . In F ig . 4 th e a c tiv i ty c u rv e due to ra d io a c t iv e z in c in th e le a d co lu m n i s p r e s e n te d . T h e a c tiv i ty c u rv e due to ra d io a c t iv e c o p p e r in th e le a d co lu m n is p re s e n te d in F ig . 5. T he ac tiv ity c u rv e due to the ra d io a c tiv e iro n in the le ad co lum n is p re s e n te d in F ig . 6. T he a c tiv ity c u rv e due to the ra d io a c tiv e cad m iu m in th e le a d co lu m n i s p r e s e n te d in F ig . 7. T h e a c tiv i ty c u rv e due to th e ra d io a c t iv e z in c in th e c a d m iu m co lu m n i s p r e s e n te d in F ig . 8, and th e a c t iv i ty cur.ve due to th e r a d io a c t iv e c a d m iu m in th e c a d m iu m c o lu m n i s p r e s e n te d in F ig . 9. T h e n u m b e r of th e c u rv e s in th e above F ig u r e s r e f e r s to th e n u m b e r of ra d io a c t iv e s a m p le s g iv e n in T a b le I.

CONCLUSIONS FR O M TH E E X P E R IM E N T A L DATA

1. T he u se of ra d io a c tiv e t r a c e r s m akes i t p o ss ib le to in v e s tig a te phenom e n a o c c u r r in g in th e r e d i s t i l l a t io n o f z in c s u c h a s th e s e p a r a t i o n o f th e c o m p o n e n ts a t s e le c te d p o in ts in th e c o lu m n .

2. T h e p lo ts in F ig s 4 -9 a llow o b s e rv a tio n o f the a p p e a ra n c e of r a d io a c tiv i ty of th e e le m e n t u n d e r s tu d y a t in d iv id u a l p o in ts in th e co lum n and to d e t e r m in e th e t im e th a t z in c r e m a in s in th e c o lu m n . T h e s e f a c ts m a y b e v e r y im p o r ta n t f o r te c h n o lo g is ts an d d e s ig n e r s o f c o lu m n s .

3. T h e p lo ts in F ig s 5 and 6, w h ich i l l u s t r a t e th e p a th s of th e h ig h - b o ilin g -p o in t im p u r it ie s in the le a d co lum n, co n firm the c a lc u la tio n s c a r r ie d

316 К. A KERMAN et al.

ou t by KRUPKOW SKI [8] on the b a s is of the th e o ry of z inc r e d is t i l la t io n . On th e b a s i s o f w o rk by K ru p k o w sk i and F ik (p a ra . 3 (c)) f u r th e r p r o g r e s s in w o rk on th e le a d co lu m n h a s b e e n ac h ie v e d . A t p r e s e n t th is co lu m n w o rk s w ith h ig h in te n s i ty of z in c v a p o r iz a tio n (to d e c r e a s e th e am o u n t of z in c B ), an d w ith s im u lta n e o u s in te n s if ic a t io n in d e p h le g m a tio n (due to r e m o v a l of in su la tio n in th e lo w er t r a y s of the colum n), in o rd e r to d e c re a s e the concentr a t io n of h ig h -b o ilin g -p o in t a d m ix tu res in the v ap o u rs en te rin g the condenser of th is co lum n. T he d a ta fro m th e m e a su re m e n ts , p re se n te d in F ig s 5 and 6, co n firm the c a lc u la tio n s and p ra c tic a l conclusions of the au th o rs c ited . U nder th e p r e s e n t c o n d itio n s of th e p r o c e s s , th e a m o u n ts of h ig h - b o il in g -p o in t m e ta ls flow ing fro m the d ep h leg m ato r to the co n d e n se r a re so sm a ll th a t the s e n s it iv i ty of ou r m e a su r in g s y s te m w as too low to d e te c t them .

4. T he m e a s u re m e n ts c a r r ie d out w ith ra d io a c tiv e c o p p e r (F ig . 5) have c o n f irm e d th e c a lc u la t io n s by K ru p k o w sk i and F ik a s to th e p o s s ib i l i ty of th e fo rm a tio n of m is ts of zinc and h ig h -b o ilin g -p o in t ad m ix tu re s in the lo w er t r a y s of th e d e p h le g m a to r in th e le a d co lu m n . T h is fa c t w as r e g i s t e r e d by m e a s u r in g p o in t N o. 4 , i .e . , in th e lo w e r p a r t o f th e d e p h le g m a to r . T h e la c k of s im i l a r b e h a v io u r in th e h ig h e r s e c t io n s o f th e d e p h le g m a to r s u b s ta n t ia te s the c a lc u la tio n s of th e a u th o rs c ite d , w ith r e s p e c t to the p ra c tic a l end of c o n d e n sa tio n of th e h ig h -b o ilin g -p o in t a d m ix tu re s o f z in c on the d e p h le g m a to r t r a y N o .4.

5. In o u r op in ion p a r t i c u la r a t te n tio n sh o u ld be p a id to th e p ro b le m of c a d m iu m s e p a r a t io n f ro m z in c in th e c a d m iu m c o lu m n . A c c o rd in g to th e a b o v e -m e n tio n e d a u th o rs , in c r e a s e in th e v a p o r iz a tio n in te n s ity d e c r e a s e s th e c a d m iu m c o n c e n tra t io n in NO z in c , b u t d e c r e a s e s th e q u a n tity of th e p r o d u c t s im u lta n e o u s ly . On th e o th e r h an d , i n c r e a s e in th e c o n d e n s a tio n in te n s ity i s fo llow ed by in c re a s e in cad m iu m c o n c e n tra tio n in the ind iv idual e le m e n ts of th e w o rk in g in te n s i ty of th e c o lu m n . In th e l a s t tw o , co n d e n s a t io n ta k e s p la c e . In th e p r o p e r c o n d e n s e r th e z in c v a p o u rs a r e m a in ly c o n d e n se d , w h e re a s th e c a d m iu m v a p o u rs w ith th e a c c o m p a n y in g z in c v a p o u rs a r e c o n d e n se d in th e c a d m iu m c a n i s t e r .

On the b a s is of a n a ly se s of the c o u rse of the se p a ra tio n of cadm ium fro m z in c , w hich fo llow s f ro m F ig s 8 and 9, th e fo llow ing p h en o m en a have b ee n o b se rv e d :

(a) T h e a c t iv i ty c u r v e s of z in c and c a d m iu m in th e lo w e r p a r t o f th e d e p h le g m a to r , in th e b o i le r and a t th e o u tle t of th e co lu m n g e n e ra l ly , a r e c o n s is te n t w ith bo th th e th e o re t ic a l c o n c lu s io n s o f th e p r o c e s s in v e s tig a te d . T he p re s e n c e of cadm ium w as o b se rv e d a t the ou tle t of the colum n only. T his w as a l s o c o n f irm e d by c h e m ic a l a n a ly s e s o f th e c o l le c te d p ro d u c ts . I t is to be no ted th a t th is o c c u r re d in sp ite of v e ry in te n s iv e v ap o riz a tio n applied , a c c o rd in g to th e p o s tu la te s a p p e a r in g in th e w o rk of K ru p k o w sk i and F ik . T he in te n s iv e v a p o r iz a tio n shou ld fav o u rab ly d e c re a s e the cadm ium con ten t in th e c o lle c te d NO z in c , a s h a s a lre a d y b ee n m en tioned .

(b) T he a c tiv ity c u rv e s of z in c and cad m iu m in the u p p e r p a r t of the d ep h le g m a to r , in the c o n d e n se r and in th e c a d m iu m -p ro d u c ts c a n is te r show con tin u o u s v a r ia t io n s in th e am o u n t of the m e ta l a p p e a rin g . T h is ap p lie s to a l l th e m e a s u r in g p o in ts m e n tio n e d . In th e c a s e o f z in c , th e s e v a r ia t io n s w ere so ap p re c ia b le in the u p p er p a r t of the co n d en se r th a t i t was im possib le to p lo t s u ita b le c u rv e s . I n c r e a s e in the am oun t of r a d io a c tiv e z inc in th e se a r e a s w as v e r y s m a l l , so th a t n e i th e r th e m a x im u m , n o r th e o n s e t of d e -


c r e a s e in th e r a d io a c tiv ity , cou ld be d e te c te d . T he a c tiv i ty c u rv e s of c a d m iu m in th e c o n d e n se r show a co n tin u o u s in c r e a s e in th e q u an tity o f m e ta l a p p e a r in g a t the tw o m e a s u r in g p o in ts . I t is n o tab le th a t ev en an ad d itio n a l 1 2 -h m e a s u r e m e n t (no t show n in th e f ig u re s ) , u s in g a r e c o r d e r , d id n o t r e v e a l any ten d en cy fo r the r a d io a c tiv ity checked to d e c re a s e . H ow ever, in th e c a d m iu m -p ro d u c ts c a n is t e r , th e m a x im u m w as found by tw o m e a s u r e m e n ts ta k e n abou t fo u r h o u rs a f te r th e ra d io a c t iv e s a m p le w as in tro d u c e d in to th e co lum n .

F ro m th e s e r e s u l t s , i t fo llow s th a t th e c o n d itio n s of z in c -c a d m iu m v a p o u rs co n d e n sa tio n h e ld a t p r e s e n t a im a t m a x im u m re c o v e r y of NO zinc and n o t a t m a x im u m o u tp u t of c a d m iu m . In o th e r w o rd s , a c c o rd in g to th e p r in c ip le s of th e p r o c e s s in v e s tig a te d , th e v e ry in te n s iv e c o n d e n sa tio n r e su lts in in c re a s in g cadm ium c o n c e n tra tio n in a ll the e lem e n ts of the w orking co lum n, and th u s a lso in th e NO z inc.

F ro m th e above i t fo llow s th a t, b e c a u s e of in te n s iv e co n d e n sa tio n , the p o s s ib i l i ty o f im p ro v in g th e p u r i ty o f r e f in e d z in c , w h ich r e s u l t s f ro m in c r e a s e d v a p o r iz a t io n in te n s i ty , i s lo s t . S uch a c o u r s e w as u n ti l r e c e n t ly ju s t if ie d f ro m e c o n o m ic a l a s p e c ts , b e c a u se the d e c re a s in g in te n s ity of cond e n s a tio n is fo llow ed by in c re a s in g am o u n ts of z in c v a p o u rs w h ich p a s s to th e c a d m iu m -p ro d u c ts c a n i s t e r , th u s d e c r e a s in g th e o u tp u t o f NO z in c .

On the o th e r hand, du rin g the technology fo rm e r ly app lied in p ro c e ss in g c a d m iu m p ro d u c ts , to o b ta in m e ta l l ic c a d m iu m by a h y d r o m e ta l lu r g ic a l m ethod , the zinc con tained in th e se p ro d u c ts was ir re p a ra b ly lo s t . The la t te r fa c to r h as n e c e s s ita te d conducting the p ro c e s s in su ch a way th a t the am ount o f z in c p a s s in g in to th e c a d m iu m c a n is te r is a s s m a ll a s p o s s ib le , ev en if th e c a d m iu m c o n ten t in NO z in c is s lig h tly in c re a s e d . A t p r e s e n t r e c o v e r y of cad m iu m fro m cad m iu m p ro d u c ts is p e r fo rm e d th ro u g h f ire re d is tiH a tio n (th is p ro c e s s w ill a lso be exam ined by m ean s of rad io a c tiv e iso to p es). D uring th is r e d is t i l l a t io n a p u re m e ta l l ic c a d m iu m is o b ta in ed and z in c co n ta in e d in th e r e c t i f y in g p ro d u c ts i s a lm o s t c o m p le te ly r e c o v e r e d . T h u s th e e c o n o m ic a rg u m e n t fo r in te n s iv e co n d e n sa tio n of z in c , d u rin g i t s re d is t iH a tio n in th e cad m iu m co lum n, m ay be abandoned .

6. T ak ing in to acco u n t th e ex p e rim en taH y p ro v ed a n a ly s is of the phenom en a o c c u rr in g in the cadm ium colum n, it a p p e a rs p o ss ib le to p ro p o se som e c h a n g e s in th e m e th o d o f co n d e n s in g z in c - c a d m iu m v a p o u r s to w a r d s d e c r e a s in g the w ork ing in te n s ity of th is e lem e n t of the co lum n. T h ese changes w ould r e s u l t in two m a in advan tages:

(a) T he cad m iu m co n ten t o f NO zinc would d e c re a s e .(b) T h e d e g re e of c a d m iu m r e c o v e r y in c a d m iu m p ro d u c ts w ould in

c r e a s e .T he l a t t e r conc lu sion , b e s id e s i ts p ra c tic a l value , is m o re ex p e rim en ta l

ev idence su p p o rtin g th e th e o ry of the zinc re d is tiU a tio n p ro c e s s p ro p o sed by K ru p k o w sk i, w ith p a r t i c u la r r e s p e c t to p a r a g ra p h 4 (c) in th e f i r s t s e c tio n o f th is p a p e r .


T he a u th o rs w ish to th a n k P ro f . Dr. A. K ru p k o w sk i c o rd ia H y fo r e x p r e s s in g h is o p in io n on th e p r e s e n t w o rk , a s w e ll a s fo r h is v a lu a b le r e -


m a rk s w h ich c o n tr ib u te d to th e a p p r o p r ia te in te r p r e ta t io n of th e e x p e r i m e n ta l d a ta .

T h e a u th o rs w ould a ls o l ik e to th a n k th e w o rk e r s o f th e R e c t if ic a tio n D e p a r tm e n t of th e W elnow iec z in c - m il l , J a n H e lia s z , J a n G a b ry s , R om an S w ierko t and M ak sy m ilian Z a ja c , as w ell a s W ilhelm K opecki, P aw el Nowak and P aw el W ro b e l, fo r th e ir help in the co lum n e x p e r im e n ts .

R E F E R E N C E S

[1] PIERCE, W. M. G. and WARING, R. K . , Trans. Am. Ins. m in . m et. Engg. 121 (1936) 445-452.[2] MATTHIES, H . , M eta ll und Erz, 33 (1936) 280-285.[3] DOMAK5KI, W. and KRUPKOWSKI, A . , M etalurgia cynku i kadm u (Warsaw) (1949) 304-315.[4J LOSKUTOW, F. M. , M etalurgia ciezkich m eta li niezelaznyck, olfiw i cynk (Katowice) (1956) 229-232.[5] MATHEWSON, C. H . , "Zinc: the Science and Technology of M etal, its Alloy and Compounds”, Reinhold

Publ. Corp. New York (1959) 338-343.[6 ] KRAPUCHIN, W. W ., POWŒDSKAJA, L. G. and JERSZOWA, S. A . , "C w ietnyje M etatty" 34 6 (1961)

23-27.[7] SWIERCZKOWA, L. G. and CHEIFEC, W. L ., "Cziste M etatty i Poluprowodniki", Trudy I Mezwuz. ,Konf.

po czist. m etall. m eta licz . sojedin. i poluprowod. m ater", M etatturgizdat (1959).[8] KRUPKOWSKI, A. and FIK, H . , Arch. Górn. i. Hutn. 2 3 (1954) 243-352.[9] KRUPKOWSKI, A . , M aterilay n-tech. Konf. po wopr. utuczsz. techn. proiz. Zn, Pb i spustw. im . m etali

(Warsaw) (1956) Izd. Moskwa (1957) 308-310.

D I S C U S S I O N

P . C. A EBERSO LD (C h a irm an ): In y o u r o r a l p r e s e n ta t io n you em p h as iz e d th e u s e of s h o r t - l iv e d r a d io is o to p e s and y o u r p a p e r i s a good i l l u s t r a t io n of how th e y m a y be u se d in qu ite l a r g e - s c a l e m e ta l lu rg ic a l s tu d ie s . I n o te , how ever, in y o u r p r in te d p ap e r th a t som e lo n g e r- liv e d iso to p es , such a s Z n 6 5 , C d n S m ^ F e 5 9 and F e 5 5 w e re a ls o u se d . W e re th e le v e ls o f th e s e lo n g e r- liv e d iso to p es in the fina l m e ta ls v e ry low and w ere the m e ta ls in tro duced in to c o m m e rc e ?

K. AKERMAN: A p art fro m iro n no lo n g -liv e d iso to p es w ere in troduced in to th e c o lu m n ë . We o b ta in ed a l l the iso to p e s by i r r a d ia t io n of p u re m e ta ls in th e r e a c to r . T h e lo n g - liv e d iso to p e s m en tio n e d in T ab le I w e re ob ta ined in th is w ay to o , b u t in s u c h s m a l l am o u n ts th a t a f te r th e e x p e r im e n ts th e z in c w as n o t r e a l ly a c tiv e a t a l l . H ow ever, a s m en tio n ed in th e p a p e r , F e 59

w as in tro d u c e d fo r p u rp o s e s of c o m p a r iso n w ith the r e s u l t s of e x p e r im e n ts u s in g Cu64. T h e c o m m e r c ia l z in c o b ta in e d d u r in g th e s e e x p e r im e n ts w as s to r e d u n t i l th e r a d io a c t iv i ty h ad d ec a y e d .

THE USE OF RESEARCH REACTORS AND SHORT-LIVED ISOTOPES IN THE STUDY OF

NUCLEAR-REACTOR FUEL MATERIALS

T . S. ELLEM AN, C . W. T O W N L E Y A N D D. N. SU N DERM AN

BA TTE LLE M EM ORIAL IN S T IT U T E , C O LU M B U S, OHIO,

U N IT E D S T A T E S OF AM ER ICA


THE USE OF RESEARCH REACTORS ANDSHORT-LIVEDISOTOPES IN THESTUDY OF NUCLEAR-REACTOR FUEL MATERIALS. A research reactor may be em ployed as a useful tool for the study of fission-product m obility in prototype nuclear fuel m aterials by producing an environment sim ilar to that expected for the normal operation of the fuel m ateria l while allowing accurate control of experim ental conditions and providing versatility in experim ental design. By varying the conditions o f irrad iation and quan tita tive ly assaying the short h a lf-life fission products released from the specim en, mechanisms of fission-product release m ay be inferred and related to the physical and chem ical properties of the fuel specimen and the fission products. In addition, useful engineering data on gross radioactivity release and expected fuel life-tim e may be obtained.

Specimens are usually irradiated in heated , double-w alled capsules immersed in the reactor pool or in reactor beam tubes, and released volatile fission products are removed from the capsule by a sweep gas. Since the relation between release rate and isotope h a lf-life is an im portant indication of m echanism , krypton and xenon fission gases with half-lives from 1 .7 s to 5. 3 d are co llected and assayed. The short-lived rare gases (krypton-89, krypton-91, krypton-92, xenon-137, xenon-138, xenon-139, xenon-140 and xenon-141) are determ ined by co llecting the n o n -v o la tile rad ioac tive daughter products on a charged wire for subsequent radiochem ical analysis, while the fission gases with longer half-lives (krypton-85m, krypton-87, krypton-88, iodine-131, xenon-133 and xenon-135) are adsorbed on cooled charcoal traps, separated into iodine, krypton, and xenon fractions by e lu tion along a chrom atographic colum n and analysed by gam m a-ray spectrom etry. N on-volatile fission products released from the specim en are deposited on an adjacent m etal foil trap which can be withdrawn at any tim e during an irradiation for analysis.

The fission-product release observed for d ifferent irrad iation conditions can be e ithe r concen tra tion - dependent or independent and can often exhib it p re fe ren tia l re lease of pa rticu la r e lem en ts, rapid fission- product release during tem perature changes, and fission-gas release after reactor shutdown. The use o f this technique allows fundamental information to be obtained on the performance of prototype fuel materials without the necessity for large testing reactors or high-level cave facilities for handling irradiated specimens.

EMPLOI DE RÉACTEURS DE RECHERCHE ET DE RADIOISOTOPES DE COURTE PERIODE DANS L'ETUDE DES COMBUSTIBLES POUR REACTEURS NUCLÉAIRES. On peut employer avec profit un réacteur de recherche pour é tudier la m obilité des produits de fission dans les prototypes de com bustibles nucléaires en créan t un m ilieu analogue à celu i dans lequel le com bustible est appelé à fonctionner norm alem ent, e t en contrôlant rigoureusem ent les conditions de l 'ex p é rien ce , tout en prévoyant une certa ine souplesse dans le d ispositif d'expérim entation. Si l'on fait varier les conditions d'irradiation et que l'on procède à une analyse quantitative des produits de fission de courte période libérés par l'échan tillon , on pourra déterm iner les mécanismes de la libération des produits de fission e t leurs rapports avec les propriétés physiques e t chimiques tant du combustib le servant d 'échan tillon que des produits de fission eux-m êm es. On pourra en outre obtenir des données de technogénie utiles sur la valeur brute de la rad ioactiv ité libérée e t la durée de v ie probable du com bustible.

En règle générale, on irradie les échantillons dans des capsules à double paroi qu'on chauffe e t introduit dans la piscine ou dans les canaux d 'irrad ia tion du réacteur, les produits de fission volatils libérés é tan t é l i minés de la capsule par un gaz de balayage. Etant donné .que le rapport entre la vitesse de dégagem ent e t la période du radioisotope constitue un indice important du mécanisme, on recueille e t ânalyse les gaz de fission- krypton e t xénon - dont la période va de 1, 7 s jusqu 'à 5 ,3 d. On déterm ine les gaz rares de courte période (krypton-89, krypton-91, krypton-92, xénon-137, xénon-138, xénon-139, xénon-140 e t xénon-141) en re cueillan t les produits de filiation radioactifs non volatils sur un fil chargé, pour les soum ettre ensuite à une analyse radiochim ique, tandis que les gaz de fission ayant une période plus longue'(krypton-85m , krypton-87,

319

320 T. S. ELLEMAN et aL

krypton-88, iode-131, xénon-133 e t xénon-135) sont absorbés sur les pièges à charbon de bois refroidis, sépares par é lu tion , sur une colonne chrom atographique, en fractions d 'iode, de krypton e t de xénon, puis an a lyses par spectrom étrie gam m a. Les produits de fission non volatils, dégagés par l 'éc h a n tillo n , se déposent sur un piège voisin constitué par une feuille m étallique qui peut être retiré, aux fins d ’analyse, à n'importe quel moment pendant l'irradiation.

La liberation des produits de fission, observée dans différentes conditions d 'irradiation, peut être ou non fonction de la concentration; i l peut souvent y avoir libération de certains élém ents prédominants, libération rapide de produits de fission lors de changements de tem pérature ou dégagement de gaz de fission après l'a rrê t du réacteur. L*application de cette technique perm et d 'obtenir des renseignements fondamentaux sur le fonctionnem ent de prototypes de com bustible, sans q u 'il soit nécessaire d 'em ployer de grands réacteurs pour les essais ou des installations souterraines spéciales pour la m anipulation des échantillons irradiés.

ИСПОЛЬЗОВАНИЕ ИССЛЕДОВАТЕЛЬСКИХ РЕАКТОРОВ И КОРОТКОЖИВУЩИХ ИЗОТОПОВ ПРИ ИЗУЧЕНИИ ТОПЛИВНЫХ МАТЕРИАЛОВ ДЛЯ ЯДЕРННХ РЕАКТОРОВ. Исследовательский реактор может быть использован для изучения подвижности продуктов деления в прототипах ядерных топливных материалов, так как он позволяет воспроизводить внешние условия, аналогичные тем, в которых оказываются топливные ма- териалы в условиях нормальной эксплуатации. Вместе с тем он позволяет точно контролировать уело* вия эксперимента и обеспечивает многообразие экспериментальных конструкций. Изменением условий облучения и путем количественного определения выделяющихся из образца продуктов деления с коротким полупериодом распада можно установить механизм высвобождения продуктов деления и его связь с физическими и химическими свойствами образца топлива и продуктов деления. Помимо этого, могут быть получены полезные сведения относительно общего количества выделяемой радиоактивности и пред* полагаемогого срока работы топливных элементов.

Образцы обычно облучаются в подогреваемых капсулах с двойными стенками, погружаемых а бассейн реактора или в реакторные каналы для облучения, а выделяемые летучие продукты деления увлекаются из капсулы струей газа. Ввиду того, что соотношение между скоростью высвобождения и полупериодом жизни радиоизотопа являются важным показателем механизма выделения, собираются и анализируются газы деления криптон и ксенон с полупериодами жизни от 1,7 сек до 5 ,3 дней. Короткоживущие редкие газы (криптон-89, криптон-91, криптон-92, ксенон-137, ксенон-138, ксенон-139, ксенон-140 и ксенон-141) определяются путем сбора нелетучих радиоактивных дочерних продуктов на заряженном электроде для последующего радиохимического анализа, тогда как газообразные продукты деления с более длительным полупериодом жизни (криптон-85, криптон-87, криптон-88, йод-131, ксенон-133 и ксенон-135) адсорбируются в охлаждаемых ловушках из древесного угля, разделяются элюированием на фракции йода, криптона и ксенона путем хроматографии ка колонке и анализируются при помощи гамма-лучевой спектрометрии. Высвобождаемые образцом нелетучие продукты деления отлагаются на соседней ловушке из металлической фольги, которая может быть вынута в любой момент облучения для анализа.

Высвобождение продуктов деления, наблюдаемое для различных условий облучения, может либо зависеть от концентрации, либо не зависеть от нее и может показывать предпочтительное выделение определенных элементов, быстрое высвобождение продуктов деления при изменении температуры и высвобождение газообразных продуктов деления после остановки реактора. Использование этого технологического метода дает возможность получить основную информацию относительно поведения материалов для прототипов топлива без необходимости использования крупных испытательных реакторов или же без устройства камер для обращения с высокоактивными образцами.

EMPLEO DE REACTORES DE INVESTIGACION Y DE ISÓTOPOS DE PERIODO CORTO EN EL ESTUDIO DE COMBUSTIBLES NUCLEARES. Los reactores de investigación pueden ser muy útiles para estudiar la movilidad de los productos de fisión en nuevos tipos de m ateriales combustibles para reactores porque perm iten trabajar en condiciones am bientales análogas a las que reinan durante la u tilización normal del combustible, a la vez que perm iten regular exac tam ente los parám etros y variar en gran m edida los diseños experim entales. Si se alteran las condiciones de la irradiación y analizan cuantitativam ente los productos de fisión de período corto que la m uestrá libera , es posible de te rm inar los m ecanism os de desprendim iento de los productos de fisión y la relación que guardan con las propiedades físicas y quím icas de la muestra de com bustible y de los pro* ductos de fisión. Además, este procedim iento perm ite obtener datos, im portantes para la ingeniería, sobre la rad iactiv idad to ta l liberada y la v ida ú til d e l com bustible.

Las m uestras se irradian generalm ente en cápsulas de doble pared que se sum ergen en la p iscina del reacto r o en sus orificios experim entales y los productos de fisión vo látiles se extraen de la cápsula con un

USE OF RESEARCH REACTORS AND SHORT-LIVED ISOTOPES 321

gas de arrastre. Com o la re lación existente entre la velocidad de desprendim iento y e l período de sem id e- sintegración de l isótopo constituye un factor im portante para determ inar e l m ecanism o de desprendim iento, se recogen y analizan e l criptón y e l xenón, gases de fisión con periodos de 1,7 s a 5 ,3 d. Los gases nobles de período corto (criptón-89, criptón-91, criptón-92, xenón-137, xenón-138, xenon-139, xenón-140 yxenón-141) se de term inan recogiendo en un a lam bre cargado e léc tr icam en te los productos de filiación radiactivos no volátiles, que se determ inan por análisis radioquím ico, mientras que los gases de fisión de período mas largo (criptón-85m , crip tón-87, crip tón-88, yodo-131, xenón-133 y xenón-135) se absorben en tram pas refrigeradas de carbón activado ; por su parte , las fracciones yodo, criptón y xenón se separan por e lución en una columna crom atográfica y se analizan por espectrometría gam m a. Los productos de fisión no volátiles liberados por la m uestra se depositan en una tram pa adyacente de lám ina m etá lica, que se puede re tirar en cualquier m om ento de la irradiación para proceder a su analisis.

La liberación de productos de fisión que se observa en diversas condiciones de irradiación puede o no depender de la concentración; con frecuencia se liberan se lec tivam en te ciertos e lem entos, se produce un desprendim iento rápido de productos de fisión durante los cam bios de tem pera tu ra y después d e l paro d e l reacto r se liberan gases de fisión. La técn ica descrita perm ite obtener datos fundam entales sobre e l rend im iento de nuevos tipos de m ateriales sin que sea preciso em plear grandes reactores de ensayo n i recintos b lin dados para m anipular muestras irradiadas de elevada actividad.

1. INTRODUCTION

A r e s e a r c h r e a c to r m a y be em p lo y ed a s a u s e fu l to o l fo r th e s tu d y of f i s s io n -p ro d u c t m o b il ity in p ro to ty p e n u c le a r fu e l m a te r i a l s by p ro d u c in g an e n v iro n m en t s im i la r to th a t ex p ected fo r th e n o rm a l o p e ra tio n of the fu e l m a t e r i a l w h ile a llo w in g a c c u r a t e c o n t r o l of e x p e r im e n ta l c o n d it io n s . By v a ry in g th e c o n d itio n s of i r r a d ia t io n an d q u a n tita tiv e ly a s s a y in g th e s h o r t h a l f - l i f e f i s s io n p ro d u c ts r e l e a s e d f ro m th e sp e c im e n , m e c h a n is m s of f is s io n -p ro ,d u c t r e l e a s e m a y b e i n f e r r e d a n d r e l a t e d to th e p h y s ic a l a n d c h e m ic a l p r o p e r t i e s o f th e fu e l s p e c im e n an d th e f is s io n p ro d u c ts . T h e fo llo w in g s e c t io n s d e s c r ib e th e eq u ip m e n t, e x p e r im e n ta l te c h n iq u e s , an d so m e ty p ic a l r e s u l t s w h ich h av e b e e n o b ta in e d f ro m r e a c t o r - f u e l s tu d ie s c a r r i e d out in th e B a tte l le R e s e a r c h R e a c to r .

2 . F A C IL IT IE S AND E Q U IP M E N T

E x p e r im e n ts invo lv ing th e r e a c to r - i r r a d i a t io n of n u c le a r fu e l m a te r ia l a r e p e r fo rm e d fo r a v a r ie ty of p u rp o se s , th e p r im a ry ones being to eva lua te th e e f f e c t o f i r r a d ia t io n on g r o s s p h y s ic a l p r o p e r t i e s , su c h a s . p h y s ic a l d im e n s io n s an d th e r m a l c o n d u c tiv ity , an d to e v a lu a te th e in te g r i ty o f th e fu e l m a te r ia l w ith r e s p e c t to f is s io n -p ro d u c t re te n tio n . In such ex p e rim e n ts i t is n e c e s s a ry to co n tro l, and in som e c a s e s v a ry ov er a wide ran g e , fa c to rs su c h a s h e a t f lux , t e m p e r a tu r e , an d r a t e o f f is s io n . In o r d e r to o b ta in in fo rm a tio n on fu e l p e r fo rm a n c e u n d er w id e ly -d iffe r in g cond itions two g e n e ra l ty p e s of e x p e r im e n ta l e q u ip m e n t a r e e m p lo y e d . O ne s y s te m , c a l le d th e "sw eep cap su le" , is a s e lf-c o n ta in e d d ev ice w ith one o r m o re fu e l sp e c im en s , h e a te r s , n eu tro n d o s im e te rs , th e rm o co u p le s , and g a s in le t and ou tle t, w hich i s in s e r t e d v e r t i c a l ly th ro u g h th e p o o l w a te r to th e r e g io n of th e r e a c t o r c o r e . It is p la c e d e i th e r in a c e n t r a l c o r e p o s it io n o r e x te r n a l to th e c o r e in th e w a te r r e f l e c to r . M ax im u m e f fe c tiv e th e r m a l - n e u t r o n f lu x in a c o r e p o s it io n is a p p ro x im a te ly 2 X 1013 nv . T h e o th e r s y s te m c o n ta in s s im i la r in s tru m e n ta tio n but is in s e r te d in an 8 - in h o r iz o n ta l beam tube w hich ex tends th ro u g h the c o n c re te b io lo g ica l sh ie ld in to th e cooling w a te r to w ithin s e v e ra l

322 T. S . ELLEMAN et al.

in c h e s of th e c o r e f a c e . M a x im u m e f fe c tiv e th e r m a l - n e u t r o n f lu x in th e s p e c im e n p o s i t io n is a b o u t 5 X 1012 nv .

2 . 1 Sw eep c a p s u le s y s te m

T he sw e e p -g a s ca p su le is em ployed in e x p e r im e n ts w here the phenom ena u n d e r s tu d y m a y b e f i s s i o n - r a t e d e p e n d e n t, w h e r e t e m p e r a t u r e i s to b e m a in ta in e d by f is s io n h e a t a lo n e , o r w h e re i r r a d ia t io n to a fu e l b u rn -u p e q u iv a le n t to th a t of p o w e r r e a c to r s i s d e s ire d .

2 .1 . 1 C a p su le d es ig n

The c o n s tru c tio n of th e in -p ile p o rtio n of the sw eep cap su le is i l lu s tra te d by th e e x a m p le in F ig . 1. T he fu e l sp e c im e n in th is c a s e i s a r ig h t c i r c u la r c y lin d e r 0. 25 -in d iam . X 0. 5 in high. The p r im a ry fu e l co n ta in e r is of heavy - w a ll c o n s tru c tio n w ith w e lls fo r th e rm o c o u p le s and tu b e s fo r in le t and ou tle t of th e sw eep o r c a r r i e r g a s . The sw eep g as t r a v e r s e s the in n e r cav ity con-

Fuel Con Detoil Scale 2-1

Fig. 1

C utaw ay drawing o f th e in -p i le sweep capsule

ta in in g th e s p e c im e n b e tw e e n th e in le t an d o u tle t tu b e . T h e fu e l c o n ta in e r is su sp e n d ed by th e sw e e p -g a s lin e s in s id e the h e a te r s h e ll . A m olybdenum b a ff le s u r ro u n d s th e s p e c im e n c o n ta in e r to re d u c e r a d ia n t h e a t lo s s . Two sh e a th e d r e s i s ta n c e h e a te r s a r e w ound in h e l ic a l g ro o v e s on th e fa c e of th e h e a te r s h e l l p ro v id in g a 2 ^ - i n h e a te d zo n e . T he o u te r c a p s u le s h e l l p r o v id e s d o u b le c o n ta in m e n t f o r th e s y s te m an d i s a t ta c h e d to th e le a d tu b e w hich ta k e s g a s and e le c tr ic a l le ad s to the in s tru m e n ta tio n above the su rfa ce o f -the p o o l. A rg o n g a s is p la c e d in s id e th e o u te r s h e ll . W elded and b ra z e d c o n s tru c t io n i s u s e d th ro u g h o u t. S ta in le s s s t e e l i s u s e d f o r c a p s u le c o m p o n en ts o p e ra te d below 1600°F, w h ile n iob ium and ta n ta lu m a r e u se d above th is te m p e r a tu re .


D"_ A ctiv ity m onitor

F ig . 2

S w eep-capsu le-experim en t gas tra in A h e lium m anifo ld ; В w et te st m eter; С he lium pu rification ; О capsu le; E daughter trap;

F holdup tank; G flex ib le coupling; H gas sam ple system ; J re frigeration and f in a l rem ova l traps;К storage tank , p a rtic le filte r; M vacuum pum p; N o il trap .

2 . 1 . 2 G a s - t r a in s y s te m

T h e s w e e p -c a p s u le g a s - t r a i n s y s te m is show n in F ig . 2. T an k h e liu m (A) is f u r th e r p u r if ie d to re m o v e m o is tu re , oxygen, n itro g e n , and h yd rogen (C), an d su p p lie d to th e c a p s u le a t 35 to 4 5 - p s i p r e s s u r e a n d a f lo w - r a te of about 0. 5 cfm . A fter th e c a r r i e r g as flow s th ro u g h the sp e c im en co n ta in e r i t p a s s e s e i th e r th ro u g h a h o ld -u p ta n k (F ), p ro v id in g a p p ro x im a te ly 1 -h d e la y f o r d e c a y of s h o r t - l iv e d f i s s io n p r o d u c ts , o r th ro u g h th e "d a u g h te r t r a p " (E) d e s c r ib e d l a t e r . T h e g a s th e n e i th e r e n t e r s o r b y p a s s e s th e c h a r c o a l - t r a p sa m p lin g s y s te m (H), a f te r w h ich it e n te r s la r g e , r e f r i g e r a te d c h a r c o a l s a fe ty t r a p s (J ). E x h a u s t f r o m th e s a fe ty t r a p s i s f i l t e r e d (L), an d i t s r a d io a c tiv ity le v e l m o n ito re d f o r s a fe ty p u rp o s e s , a f te r w hich it is e i th e r d isc h a rg e d to the s ta c k o r s to re d to allow decay (K). S cin tilla tion d e te c to rs m o n ito r th e g a s co n tin u o u sly a s it le a v e s th e h o ld -u p ta n k to p r o v id e a r e c o r d of ra d io a c t iv i ty le v e l d u rin g p e r io d s w hen th e g a s is not s a m p le d . W ith an a v e ra g e fu e l s p e c im e n co n ta in in g abou t 0. 1 g U 235 г th e to ta l c o n ta in e d f is s io n - p r o d u c t a c tiv i ty is abou t 400 c . W ith a c tiv ity le v e ls o f th i s o r d e r , s e c o n d a ry c o n ta in m e n t is r e q u i r e d on a l l h ig h - a c t iv i ty g a s l in e s . S o leno id v a lv e s on b o th th e in le t and o u tle t of th e in -p i le se c tio n r e sp o n d to u n u su a lly h ig h s ig n a ls f ro m th e co n tin u o u s m o n ito r and sh u t down th e g a s flow . A ll c o n t ro ls f o r th e h e a t e r s , th e rm o c o u p le s , g a s flow , an d r a d io a c t iv i ty m o n ito r in g s y s te m a r e m o u n te d on a c e n t r a l c o n tro l c h a s s i s lo c a te d a d ja c e n t to th e r e a c to r p o o l. A s im i l a r s y s te m h a s b ee n u s e d to hand le 10 g U 235 i r ra d ia te d 6 m onths a t an e ffec tive th e rm a l flux of 1 X 1013 nv.

324 T. S. ELLEMAN et al.

2. 2 B eam -tu b e sy s te m

T he b e a m -tu b e s y s te m is u se d in e x p e r im e n ts w h ere v e ry h igh n eu tro n f lu x i s not r e q u i r e d an d w h e re th e im p ro v e d a c c e s s ib i l i ty to in - p i le c o m p o n e n ts is a d v a n ta g e o u s .

2. 2. 1 In -p ile co m p o n en t d e s ig n

T he h e a te r , sp e c im e n h o ld e r , and s w e e p -g a s - lin e p o r tio n of th e b e a m - tu b e s y s te m ca n b e re m o v e d an d r e - u s e d , w h ile th i s is n o t p o s s ib le w ith th e sw ee p c a p s u le . F in a l c o n ta in m e n t is p ro v id e d by th e b e a m tu b e i t s e l f . T h e sp e c im e n is p la c e d n e a r th e c lo s e d end of a V y co r o r a lu m in a th im b le ex tend ing abou t 2 ft f ro m th e c o re fa c e . T he h e a te r a s se m b ly , u s in g e i th e r

N ic h ro m e o r p la tin u m r e s i s t a n c e h e a te r s o r a n in d u c tio n c o il , s u r ro u n d s th e sp e c im e n re g io n , p ro v id in g a zone of u n ifo rm te m p e ra tu re about 0. 5 -in d ia m . and 3 in long . A m e a s u re m e n t an d c o n tro l th e rm o c o u p le is p ro v id ed a t th e p o s i t io n o f th e s p e c im e n . T h e th im b le c o n ta in in g th e s p e c im e n is en c lo se d in a V ycor th im b le w hich is jo in ed to an ex ten s io n tube w ith a n e o p r e n e О - r in g , w h ich p r o v id e s th e o u tle t p a s s a g e s fo r th e c a r r i e r g a s an d in s tru m e n t le a d s . In le t and o u tle t tu b e s fo r a c a r r i e r g as and a l l in s tru m e n t le a d s fo llow an o ffse t p a th th ro u g h 1 th e c o n c re te sh ie ld in g p lug . D e ta ils r e p r e s e n ta t iv e of th e in -p i le co m p o n en ts a r e show n in F ig . 3.

Fig.3

Representative in -p ile beam -tube construction


2. 2. 2 C a r r i e r - g a s t r a in

T h e ta n k h e liu m w ith up to 5 v o l. % h y d ro g e n i s p u r i f ie d c a ta ly t ic a l ly to re m o v e oxygen a s w a te r . B oth th e oxygen and w a te r c o n te n ts a r e m o n ito r e d co n tin u o u s ly to m a in ta in le v e ls in th e 1 to 5 pp m r a n g e . T h is sy te m h a s a ls o b ee n u se d w ith oxygen a s th e c a r r i e r g a s w ith o x id e -b a se fu e l sy s te m s . The c a r r i e r g as th en flow s in and out of-the in -p ile s e c tio n 'in co n c e n t r ic tu b e s , p a s s in g o v e r th e s p e c im e n n e a r th e en d of th e th im b le .

T he c a r r i e r - g a s m o n ito rin g , sa m p lin g , and c le a n -u p sy s te m is s im ila r in des ig n to th a t u se d w ith the sw e e p -c a p su le sy s te m .

T h e s w e e p -c a p s u le an d b e a m - tu b e s y s te m s h a v e b e e n e m p lo y e d by B a tte lle in e x p e r im e n ta l w o rk of th is type fo r o v e r 5 y r and have been found sa fe , ea sy to o p e ra te , r e l ia b le , and highly su c c e s s fu l in th e study of f is s io n - p ro d u c t- r e le a s e behav iou r of m any d iffe ren t fu e l m a te r ia ls .

3. EX PER IM EN TA L TECHNIQUES

C o m p reh en siv e in -p ile s tu d ies of n u c le a r - re a c to r fuel m a te r ia ls re q u ire th e u se of a v a r ie ty of e x p e r im e n ta l te c h n iq u e s . T h e se in c lu d e m e th o d s fo r m e a s u r in g th e r e l e a s e r a t e s of bo th lo n g - and s h o r t - l iv e d g a s e o u s f is s io n p r o d u c ts a n d of c o n d e n sa b le f i s s io n p r o d u c ts , a s w e ll a s p r o c e d u r e s f o r e v a lu a tin g th e r e l e a s e m e c h a n is m .

3. 1 T h e lo n g - l iv e d g a s t r a p

T he te c h n iq u e em p lo y ed fo r th e d e te rm in a tio n of lo n g - liv e d ( T i > 1 h) k ry p to n and xenon f is s io n g a s e s r e le a s e d f ro m fu e l sp e c im en s d u rin g i r r a d i a t io n is a r e la t iv e ly s im p le o n e . T h e g a s e s a r e r e m o v e d f ro m th e sw ee p s t r e a m by a d so rb in g th e m on a c tiv a te d c h a rc o a l t r a p s m a in ta in e d a t liq u id - n itro g e n te m p e ra tu re . A ch ro m a to g ra p h ic colum n is th en em ployed to s e p a r a te th e xenon an d k ry p to n [ 1 ], w hich a r e a s s a y e d in a g a m m a -s c in til la tio n w e l l - c r y s ta l s p e c tr o m e te r . T he f is s io n g a s e s d e te rm in e d by th is tech n iq u e

TABLE I

FISSIO N GASES C O L L E C T E D ON CHARCOAL ADSORPTION TRAPS

Fission-gas species Half-life Gamma-ray energy (MeV)

X e133 5 .3 d 0.08

X e 13s 9.2 h 0.25

Kr 85 m 4.4 h 0.15

Kr «7 78 min 0.41

Kr •* 2.8 h 0.85, 0.91(a)

(a) The analysis is delayed until the 0.91-MeV gamma ray from the RbM daughter has reachedequi- librium with the Kr*8. .


a r e l i s te d in T a b le I, a long w ith th e e n e r g ie s of th e g a m m a r a y s th a t a r e m e a s u r e d .

T h e s e p a r a t io n of th e r a r e g a s e s c a n b e c o m p le te d in ab o u t 1 h . T h e c h a r c o a l - a d s o rp t io n s a m p le i s h e a te d fo r 5 m in a t 300 to 4 0 0 °C to d e s o rb th e x en o n an d k ry p to n , an d d u r in g th is h e a tin g , h e liu m is p a s s e d th ro u g h th e t r a p a t a f lo w -ra te of 120 cm3 /m in . Iodine o r o th e r so lid f is s io n p roducts re m a in on th e c h a rc o a l . The h e liu m c a r r i e s th e r a r e g a se s th ro u g h an 8 - in - long , 7 /1 6 - in -d ia m . c h ro m a to g ra p h ic co lum n of a c tiv a te d c h a rc o a l , w hich i s m a in ta in e d a t a p p ro x im a te ly 75°C. A fte r abou t 20 to 25 m in th e k ry p to n is co m p le te ly e lu ted f ro m th e co lum n and c o lle c te d on an o th e r coo led c h a r c o a l t r a p . T he c h ro m a to g ra p h ic co lu m n is th e n h e a te d fo r 30 m in a t about 300°C to e lu te th e xenon , w hich is a ls o c o l le c te d on a n o th e r t r a p .

A n a ly s is of th e k ry p to n and xenon f ra c tio n s is acco m p lish ed by m e a s u r ing th e a r e a u n d e r th e g a m m a -ra y pho topeaks fo r each iso tope in th e s e p a r a te d s a m p le s .

3. 2 T he d au g h te r t r a p

S h o r t- l iv e d f is s io n g a s e s r e le a s e d f ro m fu e l sp e c im e n s du rin g i r r a d i a tio n a r e d e te rm in e d by a techn ique involving co llec tio n and an a ly s is of th e ir n o n -v o la t i le d a u g h te r p ro d u c ts [ 2, 3]. T h is d a u g h te r - t ra p p in g te c h n iq u e is em p lo y e d fo r th e d e te rm in a tio n of th e r a r e g a s e s in th e fo llow ing f is s io n - p r o d u c t-d e c a y c h a in s :

K r 89 3 .2 minRb 89 14.9 min

-» S r 89 50.4 d .89

K r 91 10 sRb 91 Sr 91 9.1 h 91 58 d

Z r 91

K r 92 3 sRb 92 80 s

Sr 92 2.6 h r92 3.6 hZ r 92

Xe 137 9 min C s 137

Xe 138 17 min 138 32-2 mig B a 138

139 41 s « 139 9 - 5 HúnX e --------► C s -------—» Ba139 84 minLa-139

Xe 140 16 sC s 140 Ba 140 12.8 d

La140 C e 140

n i i - 7 5 ЛЛ1 short 1Л1 18 m in , t — т т п 3 .8 h 141 33 d 141X e i4 l------» C s 1 4 1 ------»■ B a 14 1------- > La141|------»• C e 1 4 1 ------- *• P r ,

T h e s p e c ie s in th e b o x e s a r e th e d a u g h te r p r o d u c ts w h ich a r e a n a ly s e d .The d au g h ter p ro d u c ts a r e c o llec te d on a ch a rg ed ro d w hich is contained

in a s ta in le s s s t e e l tu b e th ro u g h w h ich th e f is s io n g a s e s a r e sw ep t. A d raw ing of th e d au g h te r t r a p is show n in F ig . 4. T h is t r a p is in s e r te d in th e s w e e p -g a s lin e a t a p o in t a s c lo s e a s p o s s ib le to th e fu e l sp e c im e n so th a t d ecay of th e f is s io n g a s e s a h e ad of th e t r a p w ill be m in im a l. D u rin g o p e r -


Fig. 4

Daughter nap

atio n , a n eg a tiv e p o te n tia l of 1000 V is ap p lied to th e 1 /8 - in s ta in le s s - s te e l ro d . P o s i t iv e ly - c h a rg e d d au g h te r p ro d u c ts a r e c o l le c te d on th e ro d a s th e s h o r t- l iv e d f is s io n g a s e s decay in p a s s in g th ro u g h th e t r a p . To re m o v e th e r o d fo r a n a ly s i s , th e cap a t th e to p is u n b o lte d , th e e l e c t r i c a l c o n n e c tio n is b ro k en a t th e banana p lug , and the in su la te d plug th ro u g h w hich the e le c tr i c a l le ad p a s s e s is u n sc re w e d and lif te d out.

A n a ly s is of th e d au g h te r p ro d u c ts is p e r f o rm e d by a s sa y in g 1- in - lo n g se c tio n s of th e ro d in a g a m m a -sc in til la tio n w e ll - c ry s ta l s p e c tro m e te r . The d ec ay of th e v a r io u s p h o to p e ak s in th e g a m m a - r a y s p e c t r a is fo llo w ed fo r a p e r io d of t im e , an d th e d ec ay c u rv e s a r e r e s o lv e d to y ie ld th e co u n tin g r a t e s f o r e a c h is o to p e . T h e d e ta i l s of th e a n a ly s e s a r e g iv e n in T a b le II. Lai4i is a p u re b e ta - e m i t te r and th u s m u s t be d isso lv ed off th e ro d , s e p a r a te d c h e m ic a lly , and d e te rm in e d by b e ta counting.

A ty p ic a l s e t of d a ta o b ta in e d w ith th e d a u g h te r t r a p w h ich i l l u s t r a te s c o n s is te n c y in th e tra p p in g and a n a ly tic a l te c h n iq u e s is p re s e n te d in F ig . 5. T he c o n c e n tra tio n s of d a u g h te r -p ro d u c t a c t iv i t ie s a r e p lo tte d a s a fu nction of th e d is ta n c e th ro u g h th e t r a p , and th e y d e c re a s e w ith th e d is ta n c e a s one w ould p re d ic t f ro m th e h a l f - l iv e s of th e i r r e s p e c t iv e n o b le -g a s p r e c u r s o r s . F r o m th e e x p e r im e n ta l d is t r ib u t io n f o r e a c h d a u g h te r s p e c ie s , th e to ta l d au g h te r a c tiv i ty d e p o s ite d in th e t r a p i s d e te rm in e d , and th e r e le a s e r a te of th e r a r e - g a s p r e c u r s o r i s c a lc u la te d w ith th e fo llo w in g e q u a tio n :

e - V (1 - ) (1 - e -XdT)


in w hichR = r e le a s e r a t e of p a r e n t f i s s io n g a s , a to m s p e r se co n dA = q u a n tity o f d a u g h te r -p r o d u c t a c t iv i ty in t r a p a t sh u t-d o w n , d p sAd - d e c a y c o n s ta n t o f d a u g h te r , s e c - iAp = d e c a y c o n s ta n t of p a r e n t f i s s io n g a s , s e c - i

t = t r a n s i t t im e of th e g as f ro m the fu e l sp e c im en to th e t r a p e n tra n c e , seco n d s

t r = t r a n s i t t im e of th e g as th ro u g h the tr a p , seconds T = t r a p sa m p lin g tim e , se co n d s.

T h e sw eep g a s i s n o rm a lly m a in ta in e d a t a f lo w -ra te su ffic ie n t to g iv e a t r a n s i t t im e f ro m th e sp e c im e n to th e t r a p of l e s s th a n 5 s an d a t r a n s i t t im e th ro u g h th e tr a p of betw een 100 and 200 s . T ra p sam pling tim e s betw een 1 and 48 h a r e em ployed.

TABLE II

D A U G H T E R -TR A P A N ALYTICAL PROCED URES

Daughterproduct

analysed

Section of rod analysed^

(in) Half-life

Gamma- ray energy

(MeV)

Time ofanalysis^)

(h)

Principalinterferingisotope^0'

Rb89 1-40 14.9 min 1.05 0 .3 -2 4 Cs‘s«, S r«

Csi® 1-40 32.2 min 1.01 0.3 - 24 Rb» Sr»1

Ba139 1-30 84 min 0.16 0.5 - 24 SrM

Sr ® 1-6 2.6 h 1.37 1-2 4 B a»-L a“ »

Sr»i 1-20 9.7 h 0.55 2-7 2 Ba»«-Lai«

Lal« 1-6 3.8 h - 2 -2 4 --

Bat® -Lai® 1-20 12.8 d 1.6 about 200 --

Csl»7 20-40 28.6 h 0.66 about 200

(a) Portion of the rod from which sections are taken for analysis.(b) Period after shut-down over which the decay is followed.(c) Isotopes whose gamma-ray contributions must be resolved from the decay curves.

3. 3 The so lid s t r a p

ln - p i le m e a s u r e m e n ts o f th e r e l e a s e of c o n d e n sa b le o r s o l id f i s s io n p ro d u c ts a r e v e ry d ifficu lt to p e r fo rm , p a r t ic u la r ly fo r s h o r t- l iv e d sp e c ie s . It is n e c e s s a ry to t r a p a known o r d e te rm in a b le f ra c tio n of th e so lid s , rem ove th e t r a p fro m the in -p ile sy s te m quickly, and an a ly se the tr a p by ra p id ra d io c h e m ic a l m e th o d s . E x p e r im e n ts of th is ty p e a r e p e r f o rm e d in th e r e a c to r b e a m tu b e .

T he so lid s tr a p c o n s is ts of a tigh tly -w ound cy lin d er of p la tinum o r n ick e l g au z e , 6 to 8 in long an d abou t 1 / 8 in d ia m . , w hich is p la c e d in th e sw ee p - g a s e x it l in e w ith in a few in c h e s of th e fu e l s p e c im e n . T h e t r a p i s le f t in


F ig . 5

Fission-product distributions through the daughter trap.• Caesium-138; V Caesium-137; О Rubidium-89; Л Barium-139;

■ Barium-lanthanum-140; X Strontium-91; A Strontium-92; D Lanthanum -141.Linear flow-rate through the trap = 0.25 in /s.

th is p o s it io n th ro u g h o u t th e i r r a d ia t io n , and a t th e c o n c lu s io n it is ra p id ly w ith d raw n by m e a n s of a w ire c o n n e c te d to th e t r a p an d ex ten d in g th ro u g h th e sw eep lin e s to a po in t ou ts ide the r e a c to r w here th e sy s te m can be o pened .. T he t r a p can be re m o v e d f ro m th e sy s te m and r in s e d w ith n i t r ic ac id to r e c o v e r th e f is s io n p ro d u c ts in l e s s th a n 15 m in .

R ap id r a d io c h e m ic a l p ro c e d u re s a r e th e n em p lo y ed to s e p a r a te th e 12 e le m e n ts l i s t e d in T a b le III [4]. B ro m in e an d io d in e a r e s e p a r a te d in on ly 10 m in by c a rb o n te t r a c h lo r id e e x t ra c tio n s [ 5] . C a e s iu m and ru b id iu m a r e s e p a ra te d in le s s th a n 20 m in by b ism u th iod ide and c h lo ro p la tin a te p r e c ip i ta t io n s [ 6 , 7 ] . One s o lv e n t- e x t r a c t io n p r o c e d u r e i s u s e d f o r an tim o n y and t e l lu r iu m , an d a n o th e r i s u s e d to s e p a r a te c e r iu m , la n th a n u m , y t t r iu m , and z irc o n iu m -n io b iu m [4, 8 , 9]. Only abou t 20 m in is r e q u ir e d to s e p a ra te th e s e s ix e le m e n ts . B a riu m and s tro n tiu m a r e s e p a ra te d in le s s than 30 m in

TABLE III

FISSIO N PRO DU CTS D ETER M IN ED BY TH E SO LID S-TR A P TECHNIQUE


Elements separated Fission products analysed

Antimony Sb1*3 , SbB1

Barium Bal” _ ва»40 , ВаШ

Bromine Ba*3 , Br“

Cerium Ce**i , ce* «

Caesium Cs»S7 _ Csiss

Iodine ¡131 t Ц32 _ 1133 _ J134 _ Jiss

Lanthanum La140 , La141

Rubidium Rb88 , Rb”

Strontium Sr85, S r« , Sr®

Tellurium Te129, Te151, Te132 , T e 1S3m

Yttrium Y 91m, Y91, Y92 , Y93, Y94

Zirconium-Niobium Z r* -N b ® , Z r97-N b57

by a se q u e n c e of n i t r a te , c h lo r id e , and o x a la te p r e c ip i ta t io n s [5] . R e - s o lu tio n of d e c a y c u r v e s o b ta in e d by b e ta co u n tin g and g a m m a - r a y s p e c t r a l a n a ly s is of th e s e p a r a te d f is s io n e le m e n ts y ie ld s th e q u an tity d e p o s ite d on th e so lid s t r a p of e a c h of th e f is s io n p ro d u c ts l i s te d in T ab le III.

F o r an a c c u ra te d e te rm in a tio n of the r e le a s e r a te s of th e se so lid f is s io n p ro d u c ts , h o w ev er, it is n e c e s s a r y to know w hat f ra c t io n w as c o l le c te d on th e t r a p . T h is in fo rm a tio n is o b ta in e d by r in s in g th e e n t i r e sw eep s y s te m w ith a c id to r e c o v e r a l l of th e f is s io n p ro d u c ts n o t d e p o s ite d on th e t r a p . A n a ly se s a r e p e r f o rm e d on th is so lu tio n fo r lo n g e r - l iv e d f i s s io n p ro d u c ts . F ro m a know ledge of th e f ra c t io n of th e lo n g - liv e d s p e c ie s c o lle c te d on th e t r a p , th e c o l le c tio n e f f ic ie n c y f o r th e s h o r t - l iv e d f is s io n p r o d u c ts ca n be c a lc u la te d . E r r o r s in the tech n iq u e a r e s m a ll w hen th e c o llec tio n effic iency is h igh fo r a l l s p e c ie s .

4 . RESULTS

F is s io n - g a s r e l e a s e f ro m i r r a d ia te d fu e l sp e c im e n s m ay be in fluenced by s p e c im e n p o r o s i ty [ 1 1 ] , r e a c t iv e im p u r i t ie s in th e c a r r i e r g a s , p h a s e t r a n s f o r m a t io n s [12, 13] , f i s s io n - p r o d u c t c lu s te r in g [1 4 ] , an d p r e c u r s o r d iffu s io n [15] . R e le a s e of f is s io n r e c o i l s f ro m th e m a t r ix s u r ro u n d in g th e fu e l m ay m a sk th e sp e c im en g as r e le a s e and su ch f a c to rs a s s u r fa c e sp u tte r


ing by f is s io n r e c o i ls , and f is s io n - f ra g m e n t d am age to th e sp e c im e n la t t ic e e x e r t an unknow n e ffe c t. B e ca u se of th e s e m any c o m p lic a tin g f a c to r s , it is o f ten im p o s s ib le to in te r p r e t d a ta in t e r m s of a s in g le r e l e a s e m e c h a n is m a lth o u g h s i tu a tio n s s o m e tim e s o c c u r w h e re one p r o c e s s a p p e a r s to p r e d o m in a te o v er o th e rs . T he fo llow ing se c tio n s p re s e n t f i s s io n -p r o d u c t- r e le a s e d a ta r e c o rd e d in B a tte l le ’s la b o ra to r ie s w hich i l lu s t r a te th e type of r e le a s e b e h a v io u r w h ich c a n b e o b s e rv e d d u r in g in - p i le e x p e r im e n ts , a n d s o m e p o s s ib le e x p la n a tio n s of th e r e s u l t s . F is s io n - g a s r e le a s e d u r in g in - p i le i r r a d ia t io n h a s b ee n m e a s u r e d fo r th e fo llpw ing m a te r ia l s :

S ing le c r y s ta l an d s in te r e d U 0 2 ;

UO2 d is p e r s e d in g ra p h ite ;

A I 2 O3 c o a te d 120-p UO2 p a r t i c le s (both in and out of g ra p h ite m a tr ix ) ;

P y ro ly t ic -c a rb o n -c o a te d 1 2 Q - (a UC-2 p a r t ic le s (both in and out of g rap h item a tr ix );

B eO -coated 120-/lí UO2 (unsupported p a r t ic le s only); and

UO2 d isp e rs e d in g ra p h ite w ith an o u te r SiC coating .

4 .1 . 1 D iffusion

V o lu m e d if fu s io n of th e g a s a to m s in th e f is s io n a b le m a t e r i a l i s one ex p e c ted m e c h a n ism of g a s r e le a s e du ring ir ra d ia t io n . At co m p le te iso to p ic e q u ilib r iu m of th e f is s io n g a s e s , th e r e le a s e by d iffu s ion m ay be e x p re s s e d in t e r m s of th e q u an tity (R /B ), w h e re R is th e r e l e a s e r a t e of a p a r t i c u la r f i s s io n - g a s iso to p e f ro m th e sp e c im e n ( a to m s /s ) an d В is th e e q u i l ib r iu m p ro d u c tio n r a te of th e iso to p e in th e sp e c im e n ( a to m s /s ) . F o r a s p h e re [16, 1 7 , 1 8 ] ,

IT- ГИГ* Xa*- ”XlT c o t h J - 5--------V ~

R /B = 3 ( 2 )

w h e re

D = d iffu s io n co e ffic ie n t, cm 2 s _1

• X = d ecay co n s ta n t, s _1

a = s p h e re r a d iu s , cm .

F o r la rg e v a lu e s of Aa2 /D , th e eq u a tio n re d u c e s to

R /B = ; (3)

T he eq u a tio n a s s u m e s an in it ia l hom ogeneous d is tr ib u tio n of the f is s io n -g a s a to m s in th e sp e c im e n and no d iffu sion of th e p r e c u r s o r s .

4 . 1 . 2 R eco il

In add ition to d iffusion f ro m th e sp ec im en , f is s io n f ra g m e n ts a r e re c o ile d f ro m th e sp e c im e n s u r fa c e w h ere th ey com e to r e s t in th e ad jac en t su p p o rt-


ing m a te r i a l . S ince f is s io n - f r a g m e n t c o n c e n tra t io n s in th e s u r fa c e la y e r s of th e fu e l an d th e su rro u n d in g m a t r ix a r e a p p ro x im a te ly th e s a m e , E q . (3) c a n b e u s e d to p r e d ic t th e f i s s io n - g a s r e l e a s e f ro m th e m a t r ix , w ith a p p ro p r ia te changes in D and a . It often o c c u rs , how ever, th a t the su rro u n d ing m a te r i a l h a s a h ig h p o r o s i ty w h ich p e r m i ts r a p id g a s r e le a s e , o r e ls e a s ig n if ic a n t f r a c t io n of th e r e c o i l s te r m in a te d i r e c t ly in th e c a r r i e r - g a s s t r e a m . In c a s e s w h e re th e i s o to p e - r e te n t io n t im e i s s h o r t c o m p a re d to th e h a lf - life , th e r e le a s e r a te is h a lf - lif e independent and th e (R /B ) is equal to a co n s tan t

R /B = C , (4)

w h e re С i s th e f r a c t io n of to ta l f i s s io n r e c o i l s w h ich c o m e s to r e s t in th e lo w - re te n t io n m e d iu m . F o r a s p h e r e w h ich is c o m p le te ly s u r ro u n d e d by th e h ig h - p o ro s i ty m e d iu m [19]

C = 3 / 2 ( ^ ) - 1 / 2 ( - Í r )3 , (5)

w h e re 6 i s th e r e c o i l r a n g e in th e s p h e re of r a d iu s a an d < 1 .

4 .1 . 3 R e le a s e f ro m v o id s

A th i r d p o s s ib le r e le a s e p r o c e s s is d iffu sion of f is s io n g a s to en c lo se d v o id s in th e sp e c im e n , fo llo w ed by r e le a s e of th is g a s in a b u r s t w hen th e vo id s ru p tu re du ring ir ra d ia t io n . T he gas r e le a s e f ro m a s p h e re u n d er th e se cond itions m ay be r e p r e s e n te d by [ 2 0 ]

r/b = í/ F + <6>w h e re th e f i r s t t e r m r e p r e s e n t s th e d iffu s io n r e le a s e an d th e se c o n d te r m r e p r e s e n ts th e r e le a s e by vo id ru p tu re . T he te r m " a 1' r e p r e s e n ts th e ra d iu s of th e e q u iv a le n t s p h e re a s d e te rm in e d by th e c o n s ta n tly changing t r u e s u r fa c e a r e a , w h ile K i is a c o n s ta n t w h ich is a p p ro x im a te ly p r o p o r t io n a l to th e r a te a t w hich new su r fa c e a r e a is added to th e sp e c im en by void ru p tu re . If th e r a te of vo id ru p tu re is la rg e then

R / b « n/ | ~ (7)

R e c o il , d if fu s io n , an d v o id r u p tu r e a s g a s - r e l e a s e m e c h a n is m s g iv e r i s e to e q u a tio n s w h e re th e p r e d ic te d r e l e a s e i s p r o p o r t io n a l to X- * , Xo, an d X "! , r e s p e c t iv e ly , a s s e e n in E q . (3), (4) an d (7). In F ig . 6 e x p e r im e n ta l v a lu es of R /B fro m d iffe ren t ca p su le s a r e p re se n te d w hich appear to a g re e w ith th e r e le a s e beh av io u r ex p ec ted b y each of the th re e m e ch a n ism s. D ata a r e p lo tte d a s log (R /B ) v e r s u s log X to g iv e a s t r a ig h t- l in e p re se n ta t io n o f th e d a ta , arid a l l d a ta a r e n o r m a l iz e d to an (R /B ) of one a t X of 10-6 to p e r m i t e a s i e r c o m p a r is o n of th e s lo p e s . T he s c a t t e r in th e d a ta is ty p ic a l of th a t ,o b ta in e d in e x p e r im e n ts of th is n a tu re , r e f le c t in g th e m any f a c to r s in v o lv e d in th e a n a ly s i s .


T he e x p e r im e n ta l p o in ts show ing no s tro n g h a lf - lif e dependence in (R /B ) w e r e ta k e n d u r in g th e e a r ly s ta g e s of an i r r a d ia t io n of 1 2 0 -м, d e n s e UO2

w ith v ap o u r d e p o s ite d A120^ c o a tin g s d is p e r s e d in g ra p h ite . A t th is s ta g e , th e co a tin g s r e ta in e d th e f is s io n g a s e s , so the o b se rv e d r e le a s e is ap p a ren tly due to f is s io n r e c o i ls in to th e g ra p h ite f ro m known c o n tam in an t u ra n iu m in th e A I 2 O 3 c o a tin g s . T h e d a ta e x h ib itin g th e -1 /2 s lo p e c h a r a c t e r i s t i c of d if fu s io n w e re o b ta in e d d u r in g i r r a d ia t io n a t 1300°F of a g r a p h i te s p h e re w ith a d e fe c te d o u te r SiC co a tin g an d 100 to 200-м , d e n se UC d is p e r s e d in th e g ra p h ite . The im p lic a tio n is th a t d iffusion f ro m th e fu e l and th e g rap h ite p ro d u c e d th e o b se rv e d d iffu s ion d is t r ib u t io n . T he d a ta show ing th e s lo p e of - 3 / 2 w e re ta k e n d u r in g i r r a d ia t io n of A l 2 0 3 - c o a te d 120-м UO2 p a r t i c l e s d i s p e r s e d in g r a p h i te a t a t im e w hen th e p a r t i c l e c o a tin g s w e re b e l ie v e d to be c ra ck in g . The void sp ace betw een the U 0 2 and the in ta c t A I2 O3 coatings m a y s e r v e a s a r e s e r v o i r fo r f i s s io n g a s e s w h ich ca n be r e le a s e d to g iv e th e e x p e c te d h a l f - l i f e d is t r ib u t io n w hen th e c o a tin g s c r a c k .

T h e ab o v e s p e c im e n s e x h ib ite d r e l e a s e c h a r a c t e r i s t i c s o f r e c o i l , d iffu sion , and e m is s io n f ro m v o ids u n d e r i r ra d ia t io n cond itions w h ere th e se

to'* io"‘ 10'4 10'* to-* iff'

Fission Gas Decay Constant X (s )“*133 135 85m 88 87 138 137 89 139 140 91

L J--------------------- 1—I—I_________________________________I_____I________LI_______ I________ I IFig . 6

Com parison o f observed and expec ted gas re lease for d ifferen t ex p erim en ta l cond itions.


m e c h a n is m s se e m e d re a s o n a b le . In g e n e ra l , f i s s io n - g a s r e l e a s e is m o re c o m p le x an d i t is u s u a l ly d if f ic u lt to a s c r ib e a s im p le e x p la n a tio n to th e o b s e rv e d r e l e a s e . M o re ty p ic a l of th e d a ta w h ich a r e u s u a l ly o b ta in e d is th e c u rv e in F ig . 6 w h ich show s a s lo p e of abou t -0 . 25. T h e se g a s - r e l e a s e d a ta w e re o b ta in ed d u rin g th e i r r a d ia t io n of u n su p p o rte d A I2O 3 - c o a te d UO2

p a r t i c l e s w ith c r a c k e d bu t in ta c t c o a tin g s a t a m b ie n t t e m p e r a tu r e s (about 150°C). The re la t iv e ly high o b se rv e d g as r e le a s e ( R/ B about 10-4 fo r X ei33 ) and th e h a lf - l if e dependence se e m in c o n s is te n t w ith a r e c o i l m e ch a n ism and th e low i r r a d ia t io n te m p e r a tu r e w ould s e e m to e l im in a te v o lu m e d iffu s io n . A re a s o n a b le but u n p ro v e d ex p la n a tio n of th e r e s u l t s is s u g g e s te d by w o rk of E R S H L E R an d L A P T E V A [21] who s tu d ie d s p u t te r in g of u ra n iu m f ro m a s u r fa c e by f is s io n r e c o i l s . T h e a u th o rs show ed th a t u ra n iu m a to m s a r e re m o v e d f ro m a s u r f a c e by f i s s io n r e c o i l s an d RO G ERS [22] sh o w ed th a t a la y e r of sp u tte re d u ran iu m a to m s bu ild up on a c a tc h e r fo il p laced ad jacen t to a u ran iu m s u rfa c e during ir ra d ia t io n and the la y e r re a c h e s an eq u ilib riu m th ic k n e s s of ab o u t 10 A. C o n tin u o u s e q u i l ib r a t io n of a 10 À u r a n iu m f i lm b e tw e e n th e c o r e an d th e u n d e r s id e of th e A I 2O3 c o a tin g on c o a te d f u e l p a r t i c l e s c o u ld p ro d u c e a f i s s io n g a s ( R / B ) of ab o u t 10""4 , in a g r e e m e n t w ith th e o b s e rv e d r e l e a s e , an d a h a l f - l i f e d ep e n d en c e w ou ld o c c u r if g a s a to m s n e a r th e b o tto m of th e f ilm h ad a d if fe re n t r e l e a s e p ro b á b il i ty th a n th o s e n e a r th e to p .

4. 1. 4 R e le a s e a f te r long i r r a d ia t io n t im e s

T he d iffu s io n and r e c o i l e q u a tio n s p r e s e n te d in th e above s e c tio n s r e p re s e n t r e le a s e a t e q u ilib riu m , and th is r a te should re m a in constan t, b a rr in g c h a n g e s in th e fu e l s t r u c t u r e o r e x c e s s iv e b u rn -u p . I n c r e a s e s in r e l e a s e r a te w ith tim e a r e both ex p ected and o b se rv e d , how ever, a s c e ra m ic coatings

Fig . 7

Fission-gas re lease during long irrad ia tion tim es


on f u e l p a r t i c l e s c r a c k a f te r e x te n d e d i r r a d i a t i o n a n d g e n e r a l s p e c im e n d e te r io r a t io n o c c u r s . Som ew hat l e s s e x p e c te d a r e d e c r e a s e s in f is s io n - p ro d u c t r e le a s e w ith in c re a s in g e x p o s u re , bu t th is to o o c c u r s . F ig . 7 sh o w s th e ch an g e in f is s io n - g a s r e l e a s e w ith t im e fo r f iv e iso to p e s f ro m A I 2 O3 - c o a te d UO 2 p a r t ic le s su sp en d ed in g ra p h ite and i l lu s t r a te s d e c re a s in g r e le a s e w ith t im e . A la r g e f r a c t i o n of th e p a r t i c l e c o a tin g s w e r e c r a c k e d in a n i n i t i a l i r r a d ia t io n , ^an d th e s p e c im e n w a s th e n c o o le d f o r 44 d, r e s u l t in g in th e d e c a y of a l l of th e m e a s u r e d f is s io n g a s e s . T h e sp e c im e n w as th e n i r r a d ia te d fo r 37 d a t a te m p e r a tu re of 650 ± 60°C, r e s u lt in g in th e f is s io n - g a s - r e l e a s e c u rv e s show n in th e f ig u re . T he d e c re a s in g r e le a s e w ith tim e co u ld be due to a d e c r e a s e d r a t e of c ra c k in g , w ith a r e s u l t in g d e c r e a s e in th e r e l e a s e of s to r e d g a s . H o w ev er, th is e x p la n a tio n d o es no t a g r e e w ith th e o b s e rv e d r e le a s e r a t i o s o f th e v a r io u s is o to p e s . A n a l te r n a t iv e e x p la n a tio n is th a t g as a to m s becom e im m o b ilized a t t r a p s co n s is tin g of f is s io n - f ra g m e n t c lu s te r s and la t t ic e d e fec ts in the sp e c im en and r e s u l t in a low ered r e le a s e r a te . T he d e m o n s tra te d e x is te n c e of f is s io n - g a s b u b b les in i r r a d i a te d f is s io n a b le m a te r ia l s [14, 23] le n d s su p p o rt to th is v iew .

S im ila r d e c r e a s e s in g a s r e l e a s e w ith t im e h a v e b e e n o b s e rv e d w ith s in t e r e d UO 2 s p e c im e n s w h e re p o s t - i r r a d i a t i o n e x a m in a tio n sh o w ed th a t th e d e c r e a s e in g a s r e l e a s e co u ld b e a t t r ib u te d to in c r e a s e s in g r a in s iz e d u r in g i r r a d ia t io n . T he i r r a d ia t io n of 93% d e n se U 0 2 ( s in te re d a t 2600°F) fo r 38 h a t 3000°F r e s u l t e d in a f a c to r o f 20 d e c r e a s e in g a s r e l e a s e , and p o s t - i r r a d ia t io n ex a m in a tio n show ed th a t g ra in s iz e had in c re a s e d a p p ro x im a te ly a fa c to r of 100 d u rin g th e i r r a d ia t io n [24] .

4. 2 P r e c u r s o r r e le a s e

F is s io n -g a s p r e c u r s o r s w hich a r e r e le a s e d fro m an ir ra d ia te d sp ec im en w ill r e l e a s e f is s io n g a s to th e c a r r i e r g á s a s th e y d e c a y . T h e r e f o r e , th e d e te c tio n of f i s s io n g a s e s in sa m p lin g t r a p s i s not s u f f ic ie n t e v id e n c e th a t th e g a s e s th e m s e lv e s w e re r e le a s e d f ro m th e sp e c im e n . V a rio u s eq u a tio n s h av e b e e n d e r iv e d [25] w h e re th e p r e s e n c e of p r e c u r s o r d iffu s io n m a y be in f e r r e d f ro m th e o b se rv e d e q u i l ib r iu m - r e le a s e - r a te r a t io s of th e d iffe ren t f i s s io n g a s e s , b u t th e r e p r o d u c ib i l i ty of th e e x p e r im e n ta l d a ta i s r a r e l y good enough to ju s t ify th is a p p ro a c h . T he fo llo w in g te c h n iq u e s h a v e b e e n u s e d to c o n firm p r e c u r s o r r e le a s e and, a t v a r io u s tim e s , a l l of th e se have g iv e n p o s it iv e in d ic a tio n s of f i s s io n - g a s p r e c u r s o r s w hich a r e e x te r n a l to th e sp e c im e n .

4 . 2 . 1 A n a ly s is o f c h a r c o a l t r a p s

A ssay of th e c h a rc o a l t r a p s u se d to c o llec t th e f is s io n g a se s occasionally sh o w ed th e p r e s e n c e of 1133 , 1135 , an d p o s s ib ly Tei33m . T h is m e th o d is n o n - q u a n ti ta t iv e , , s in c e t r a p p in g o c c u r s in o th e r p a r t s of th e s y s te m , and i t is a p p lic a b le on ly to long h a l f - l i f e p r e c u r s o r s .

4. 2. 2 A n a ly s is o f s o lid t r a p s

S olid t r a p s p la c e d a d ja c e n t to th e i r r a d ia t io n sp e c im e n r e g u la r ly show r e l e a s e of I, B r , T e , and Sb is o to p e s . T h e se e le m e n ts a r e a l l know n p r e


c u r s o r s of th e r a r e g a s e s , an d by a s s a y of th o s e is o to p e s w h ich o c c u r in th e f is s io n -g a s ch a in s , it h as been p o ss ib le to ob ta in e s tim a te s of p r e c u r s o r r e le a s e . P r in c ip a l d isa d v a n ta g e s to th is m eth o d w e re th a t no d a ta w e re ob ta in e d f o r short, h a l f - l i f e p r e c u r s o r s an d on ly one m e a s u r e m e n t c o u ld be c a r r i e d out p e r s p e c im e n ru n .

4. 2. 3 G as r e l e a s e d u r in g s t a r t - u p

T h e r a t e a t w h ich f i s s io n - g a s r e l e a s e a p p ro a c h e s e q u i l ib r iu m a f te r s t a r t - u p is in f lu e n c e d by th e r e l e a s e m e c h a n is m . If p r e c u r s o r d if fu s io n i s th e on ly r e l e a s e p r o c e s s , th e a p p e a ra n c e of f i s s io n g a s e s in th e sw eep s t r e a m is d e te rm in e d by the p r e c u r s o r h a lf - liv e s only, w h erea s if th e g a se s th e m s e lv e s d if fu se , th e t im e r e q u i r e d to o b ta in e q u i l ib r iu m is a fu n c tio n of b o th th e p r e c u r s o r an d f is s io n - g a s h a l f - l iv e s . D a ta ta k e n s h o r t ly a f te r s ta r t - u p u su a lly show ed th a t e q u ilib r iu m w as ap p ro a ch ed m o re ra p id ly th an w ou ld b e e x p e c te d f ro m d if fu s io n of g a s e s on ly , in d ic a tin g r e l e a s e of th e p r e c u r s o r s . One d isa d v a n ta g e to th e m e th o d is th a t th e f i r s t s e v e r a l days of i r r a d i a t i o n is o ften a t im e w hen c h a n g e s in th e s p e c im e n o c c u r w h ich a ffec t th e f i s s io n - p r o d u c t- r e le a s e p r o p e r t ie s . T h ese changes in te r fe re w ith e x p e r im e n ts d es ig n ed to d e tec t p r e c u r s o r r e le a s e .

4. 2. 4 G as r e le a s e a f te r shu t-dow n

If th e n e u tro n f lu x an d te m p e r a tu r e of an i r r a d ia t io n c a p s u le a r e cu t s im u lta n e o u s ly , th e on ly e x p e c te d r e le a s e of f is s io n g a s e s to th e sa m p lin g s y s te m w ould be f ro m f is s io n - g a s p r e c u r s o r s w h ich a r e d e p o s ite d on th e w a lls of the c a p su le . G a s - r e le a s e r a te s a f te r shu t-dow n can , th e re fo re , be u s e d to d e te rm in e th e r e le a s e of p r e c u r s o r s f ro m th e sp e c im e n . In c a s e s w h ere it is u n d e s ira b le to low er th e sp ec im en te m p e ra tu re during shut-dow n, p r e c u r s o r e f fe c ts ca n s t i l l be s e e n , s in c e g a s d iffu s ing f ro m th e sp e c im e n an d g a s r e l e a s e d on ly f ro m d ec ay of p r e c u r s o r s d e p o s ite d o u ts id e of th e s p e c im e n w ill e x h ib it d if fe re n t t im e r a t e s of c h a n g e f o r g a s r e l e a s e . In F ig . 8, th e p re d ic te d g a s - r e l e a s e r a te s a t co n s ta n t te m p e ra tu re a r e p lo tte d fo r v a r io u s t im e s a f t e r sh u t-d o w n , a s s u m in g , in one c a s e , th a t o n ly th e f is s io n g a s is r e le a s e d f ro m th e sp e c im e n , and in th e o th e r c a s e , th a t only th e h a lid e p r e c u r s o r w h ich d e c a y s to th e f i s s io n g a s is r e le a s e d . I t w as a s su m e d th a t the d iffusion co e ffic ie n ts a f te r shu t-dow n a re the sam e a s th o se b e fo re an d th a t th e e q u a tio n s f o r p o s t - i r r a d i a t i o n d if fu s io n r e l e a s e (w ith a p p r o p r ia te c h a n g e s f o r is o to p e b u ild -u p an d d e c a y a n d th e s u r f a c e c o n c e n tr a t io n g r a d ie n t p r e s e n t a t th e t im e of sh u t-d o w n ) a r e a p p l ic a b le . T h e tw o s e t s of p r e d ic te d c u r v e s d if fe r s h a r p ly f o r Kr87 , Kr88 , a n d Kr85m w h e re th e h a l id e an d g a s h a l f - l iv e s a r e q u ite d if fe re n t , w h ile Xei33 a n d Xei35 show m u c h l e s s d iv e rg e n c e due to th e s im i la r i t y in h a l id e an d g a s h a l f - l iv e s . E x p e r im e n ta l r e s u l t s p r e s e n te d on th e c u rv e w e re ta k e n a f te r sh u t-d o w n f ro m th r e e c a p s u le s co n ta in in g 120-p UO 2 d is p e rs e d in g ra p h ite , 160-м A l 2 0 3 -c o a te d UO2 p a r t i c le s , and s in te r e d UO2 . The k ry p to n -re le a s e d a ta show th a t a s u b s ta n t ia l f r a c t io n of th e m e a s u r e d k ry p to n c o m e s f ro m d ec ay of p r e c u r s o r s e x te r n a l to th e sp e c im e n but th a t so m e r e l e a s e of g a s f r o m th e s p e c im e n a l s o o c c u r s . T h e x en o n d a ta a r e l e s s c o n c lu s iv e b u t,


lor

-a- ■*s - 4 —̂ -C " KHS\ ' ч

IND*

Xe13’V \\ \

\\

□□ Д

4k У

\ +

----С\ \ \Д

u L-4 "Xek 9

С— *r \ Î i \\ t \ 'X ,!38

1\ \ »1 \\ 9

\\ \ \« \

1 \ <r .Kr .Kr11

1 . •<i) Kr"» Kr®8 h К r 85" ^ Xe,3St

» UI H

1 1Î7 — Kr® mKr

Kr8®!io2 io3 io4

T i me After S h u t - D o w n ( s )I05 10e

Fig . 8

Fission-gas re lease a fte r reacto r shut-dow npred ic ted curve for diffusion o f gas on ly .

-p red ic ted curve for diffusion of ha lid e precursor on ly .

in g e n e r a l , th e y show a m u c h c lo s e r c o r r e s p o n d e n c e to th e p r e c u r s o r - r e l e a s e c u r v e s th a n to th o s e fo r g a s r e l e a s e .

T h e d e m o n s tr a tio n th a t a s u b s ta n t ia l f r a c t io n of th e g a s r e l e a s e o ften c o m e s f ro m h a l id e p r e c u r s o r s e x t e r n a l to th e s p e c im e n c o m p lic a te s th e in te r p r e ta t io n of r e s u l t s a n d a l s o g iv e s r i s e to s p e c u la t io n th a t e le m e n ts f u r th e r b ack in th e decay ch a in s th a n iod ine and b ro m in e m ay a lso be c o n tr i bu ting s ig n ific an tly to th e r e s u l t s .

4. 3 E ffec t of te m p e ra tu re changes on g a s r e le a s e

A n in c r e a s e in s p e c im e n t e m p e r a t u r e p ro d u c e s a b u r s t o f r e l e a s e d f i s s io n g a s w h ich s lo w ly d e c r e a s e s u n t i l a new e q u i l ib r iu m (R /B ) is e s ta b l is h e d . The b u r s t o f te n p e r s i s t s f o r s e v e r a l h o u rs , an d m e a s u re d r e le a s e d u rin g th e b u r s t m ay be 8 to 10 t im e s th e e q u ilib r iu m r e le a s e . STUBBS and WALTON [26] o b se rv e d a b u rs t r e le a s e during i r ra d ia t io n of UO2 and showed th a t , f o r a d if fu s io n m e c h a n is m , a h ig h r a t e of g a s r e l e a s e i s e x p e c te d , foHowing a te m p e ra tu re change, u n til a new diffusion g ra d ie n t is e s ta b lish e d .

In F ig . 9, r e le a s e b u r s ts o b se rv e d fo r X e i3 5 and X e l3 3 during a te m p e ra tu r e in c re a s e a r e p lo tte d a s th e r a t io of the o b se rv e d r e le a s e r a te o v er th e e q u i l ib r iu m r e l e a s e r a t e fo r v a r io u s h e a tin g t im e s . T he X e i3 3 c u rv e w as o b ta in e d f ro m g a s s a m p le s o b ta in e d d u r in g a t e m p e r a t u r e in c r e a s e f r o m 1800°F to 2000°F f o r a 99% d e n se s in t e r e d UO2 s p e c im e n , w h ile th e X e135

c u rv e w as o b ta in e d f ro m a l in e m o n ito r s e t on th e X e i 3 5 p h o to p e ak d u rin g a t e m p e r a tu r e in c r e a s e f ro m 880°F to 1190°F f o r a n A I 2 O3 -U O 2 c o a te d - p a r t i c l e fu e l s p e c im e n . A lso in c lu d e d in th e f ig u re a r e c u r v e s w h ich show


H eating T im e ( b )

F ig .9

Fission-gas re lease during a tem pera tu re increase___________ observed curve.____________pred ic ted curve.

th e e x p e c te d r e l e a s e - r a t e change if th e b u r s t is due to d iffu s ion and o c c u rs b e c a u s e th e c o n c e n tra t io n g ra d ie n t is ch an g in g . On th e b a s is of e q u a tio n s d e r iv e d by B EC K [25] th e s e p r e d ic te d c u rv e s ex h ib it f a i r a g re e m e n t w ith th e o b se rv e d X e i3 5 r e le a s e , but th e o b se rv e d X e i3 3 r e le a s e d rops off m o re r a p id ly th a n ex p e c te d . W hile a s im i la r r a p id d e c r e a s e fo r Х е ^ з h a s b een o b s e rv e d in o th e r e x p e r im e n ts , th e r e s u l t s a r e no t su f f ic ie n tly conv incing to e l im in a te th e d iffu s io n e x p lan a tio n fo r th e b u r s t .

O th e r w o rk e r s [15, 27] h av e o b s e rv e d a b u r s t of f i s s io n g a s d u rin g a coo ling t r a n s i t io n a s w e ll a s d u rin g a h e a tin g ch an g e . T h is e ffec t h a s b ee n o b se rv e d d u rin g bo th in -p ile and p o s t - i r r a d ia t io n e x p e r im e n ts and h as been v a r io u s ly a t t r ib u te d to th e ru p tu re of g a s -c o n ta in in g v o id s in th e sp e c im e n a n d to th e f o rm a tio n of a s u b s to ic h io m e tr ic o x id e in th e f u e l s p e c im e n .

4 . 4 ISffect o f o x y g en on g a s r e l e a s e

T he p r e s e n c e of oxygen o r w a te r v ap o u r in th e c a r r i e r sw eep g as p r o d u c e s a n im m e d ia te an d p ro n o u n c e d in c r e a s e in th e f i s s io n - g a s - r e l e a s e r a te . F is s io n -g a s - re le a s e r a te s m ay in c re a s e an o rd e r of m agnitude o r m o re s h o r tly a f te r the in tro d u c tio n of oxygen and w hile the rem o v a l of th is elem en t f ro m th e c a r r i e r g a s m a y r e s u l t in so m e re d u c tio n in f is s io n g a s r e le a s e , th e r a te s r a r e ly r e tu r n to anyth ing ap p roach ing the o r ig in a l v a lu e s . We have c a r r i e d out no c o n t ro l le d e x p e r im e n ts to s tu d y an o x y g en e f fe c t b u t th e o c c a s io n a l a i r le a k s w h ich o c c u r in th e g a s sw ee p s y s te m h av e a d e q u a te ly d e m o n s tr a te d an in c r e a s e d r e l e a s e in th e p r e s e n c e of oxygen . An oxygen


e ffe c t is ex p e c ted s in c e bo th th e u ra n iu m c a rb id e s and UO2 m ay be ox id ized and a n u m b er of in v e s tig a to rs have show n th a t f is s io n g as r e le a s e in c re a s e s a s th e o x y g e n -to -u ra n iu m r a t io in the sp e c im en in c re a s e s [2 8 -3 0 ].

4. 5 R e le a se of so lid f is s io n p ro d u c ts

R e le a s e of so lid f is s io n p ro d u c ts du ring i r ra d ia t io n h a s b een m e a s u re d by th e so lid trap p in g techn ique d e s c r ib e d in an e a r l ie r se c tio n . Only s e v e r a l e x p e r im e n ts have b ee n p e r fo rm e d and th e d a ta a r e too in co m p le te to p e rm it a g e n e r a l d is c u s s io n o f th e r e l e a s e b e h a v io u r of s o l id f i s s io n p r o d u c ts .


T he a u th o rs w ish to thank N. E . M ille r , R . L. R itzm an , and F . A. Rough of B a tte lle fo r su pp ly ing in fo rm a tio n on c a p su le d es ig n and f is s io n - g a s r e le a s e .

R E F E R E N C E S

[1 ] KOCH, R .C . and GRAND Y, G.L , "Xenon-krypton Separation by gas Chromatography", Nucleonics 187 (1960) 76.

[2 ] TOWNLEY, C .W ., HOWES, J .E . , J r . , RAINES, G .E ., DIETHORN, W .S. and SUN DERM AN, D .N .,"A radiochem ical Technique for the Determination of short-lived fission Gases", Nucl. Sci. and Engr. 10 4(1961) 346.

[3 ] TOWNLEY, C .W ., MILLER, N .E ., ELLEMAN, T .S . and SUNDERMAN, D .N . , Im proved T echn ique - for the D eterm ination o f short lived fission product Gases, N ucl. S ci. and Engr. 13 3 (1962) 297.

[4 ] TOWNLEY, C .W ., ELLEMAN, T .S . and SUNDERMAN, D .N. , "R adiochem ical separation Techniques for short-lived fission Products", Trans. Am. N ucl. Soc. 5 1 (1962) 194.

[5 ] GLENDENIN, L .E . and METCALF, R .P . , "Im proved D eterm ination o f iod ine A ctiv ity in Fission**, N ational N uclear Energy Series 9 3 (1 9 5 1 ) 1625.

[6 ] EVANS, H .B . , Bismuth iod ide M ethod for th e D eterm ina tion o f cesium A ctiv ity in Fission, i b i d . , p . 1646.

[7 ] EVANS, H .B . and SCHUMAN, R. P . , Studies o f th e Separation o f Rubidium from fission M a te ria l, i b id . , p . 1456.

[8 ] McCOWN, J .J . and LARSEN, R .P ., "Radiochem ical Determ ination of cerium liquid-liquid Extraction", A nal. C hem . 32 (1960) 597.

[9 ] McCOWN, J .J . and LARSEN, R .P . , "Radiochem ical Determ ination of to ta l rare Earths by liquid-liquid Extraction", Anal. C hem . 33 (1961) 1003.

[1 0 ] SUNDERMAN, D .N . and MEINKE, W .W ., "Evaluation of rad iochem ical separation Procedures", A nal. Chem . 29 (1957) 1578.

[1 1 ] BOOTH, A .H . and RYMER, G . T . , D e term ination o f the diffusion Constant o f fission Xenon in U O j Crystals and sin tered C om pacts, AECL-690 (1958).

[1 2 ] SCOTT, К .T . and BUDDERY, J .H . , "The Release ofK ryp ton-85 from irrad iated Uranium on therm al C ycling through the phase C hanges", J . Nuc. M at. 5 1 (1962) 94-100.

[1 3 ] ŸAJIMA, S . , SCHIBA, S . , KAMEMOTO, Y . and SHIBA, K . , "T he Use o f re co il fission ra re Gases for the Study o f the C hange in c rystal S tructu re", B u ll..C h em . S o c . , Japan 33 (1960) 4 2 6 -7 .

[1 4 ] GREENWOOD, G .W ., ’’The Role o f V acancies and D islocations in th e N ucléa tion and Growth o f gas Bubbles in irrad ia ted fissile M ate ria l" , J . N uc. M at. 1 (D ec . 1959) 305*24,

[1 5 ] CARROLL, R .M ., Continuous Release o f fission Gas from UOt during Irrad iation , ASTM Pub. 306 (M arch , 1962) 110-20.

[16] BOOTH, A .H ., "A suggested M ethod for C alculating the Diffusion of radioactive rare gas fission Products from иОг fuel Elem ents and a Discussion o f proposed in -reac to r Experim ents th a t m ay be used to te s t its V a lid ity " , DCI-27 ( S e p t . , 1957).


[1 7 ] COTTRELL, W .B ., CULVER, H .N ., SCOTT, J .L . and YAROSH, M .M :, Fission product Release from U O t, ORNL-2935 (1960).

£18] BECK, S . , .The Diffusion o f rad ioac tive fission Products from porous fuel E lem ents, BMI-1433 (1960).[1 9 ] TOBIAS, M . , Som e e lem en ta ry Results concerning escape P robab ilities o f P articles o f fixed Range

generated in Spheres, C F -6 0 -9 -4 4 (1960).[2 0 ] RAINES, G .E . and GOLDTHWAITE, W .H . "In -p ile fission -gas-re lease Behavior o f a lu m in a -co a ted

U 0 2 P artic les irrad iated to h igh B um -up, BM I-1552 (1961).[21 ] ERSHLER, B .V . and LAPTEVA, F .S . , "The Evaporation of M etals by fission Fragments", J .N u c . Energyll

4 (1957) 411.[22 ] ROGERS, Ejection of Uranium by fission Fragments, AERE-R-3908 (1961).[23 ] BELLE, I . , Uranium dioxide Properties and nuclear Applications, pp .552-565, USAEC.[24 ] ROUGH, F .A ., private com m unication.[2 5 ] RAINES,' G .E ., TOWNLEY, C .W . , BECK, S .D . and GOLDTHWAITE, W .H ., A M ethod for the Study

and C orrela tion o f fission Gas re lease Behavior of fuel M aterials during Irrad iation , BMI-1548 (1961).[2 6 ] STUBBS, F .J . and WALTON, G .N . , Fission 'gas Emission during tem pera tu re Changes in a R eactor,

AERE-R-3093 (1959).[2 7 ] ROTHWELL, E . , The Release o f Kr'85 from irradiated UOs on post-irradiation Annealing, AERE-R-3672

(1961).[2 8 ] LINDNER, R. and MATZKE, H . , "The Diffusion o f Xe*M in UOs o f varying oxygen C on ten t" , Z . ffir

N aturfo rsch ., 13A (1958) 794; also AERE-TRANS-845; also Z . Naturforsch. 14A (1959) 582-84.[2 9 ] AUSKERN, A ., Further Work on th e Diffusion o f Kr86 from UOs Powder, W APD-TM -255 (1960).[3 0 ] MORGAN. J .G . , MORGAN, M .T . and OSBORNE, M .F . , Fission gas Release from UO*, C F -60 -7 -11

(1960).

D I S C U S S I O N

P . C . AEBERSOLD (C hairm an): D r. E lle m an ’s p ap e r show s th a t iso tope techno logy can be of u s e in n u c le a r r e a c to r technology and it a lso i l lu s tr a te s th e v e r y in te r e s t in g an d t r ic k y r a d io c h e m is t r y of p a re n t-a n d -d a u g li te r r e la t io n s h ip s .

P . N ELSO N : H ave you d e te rm in e d v a lu e s fo r d iffu s io n c o e ff ic ie n ts of th e d a u g h te rs in th e v a r io u s m a te r ia l s you have s tu d ie d ?

T . S. E L L E M A N : Y es, we h av e d e te rm in e d d iffu s io n c o e ff ic ie n ts , by m e a n s of p o s t - i r r a d i a t i o n h e a tin g e x p e r im e n ts . T h e v a lu e s o b ta in e d a r e in f a i r l y good a g re e m e n t w ith o b s e rv e d in - p i le r e l e a s e r e s u l t s .

F . NELSON: I w ould a lso lik e to m ake a g e n e ra l com m ent, w ith re g a rd to th e o v e r la p p in g u s e of d if fu s io n th e o r y in th e v a r io u s s c ie n c e s . In th e p a p e r "Som e te c h n iq u e s fo r iso la tin g and u sin g s h o r t- l iv e d r a d io is o to p e s " * w e d is c u s s e d d a u g h te r s e p a r a t io n f ro m s p h e r ic a l r e s in b e a d s , w h ich is a p ro b le m a n a lo g o u s to y o u r e x p e r im e n ts w ith c e r a m ic s p h e re s . In th e f ie ld o f p h y s ic s , s im i l a r d iffu s io n c o n s id e r a t io n s a l s o ap p ly to th e d if fu s io n of n e u t ro n s f ro m — to c a r r y th ro u g h th e a n a lo g y — s p h e r ic a l r e a c t o r s .

D. A. YASHIN: I am in te r e s te d in th e u se of th is te ch n iq u e of a s sa y in g th e d augh ter p ro d u c ts of f is s io n g a s e s (a e ro so ls ) fo r the p u rp o se of detecting b r e a k s in fu e l-e le m e n t cann ing . In ou r P h y s ic o - te c h n ic a l In s titu te a s im ila r te c h n iq u e h a s b e e n w o rk e d ou t an d i s now b e in g u s e d to c h e c k th e le a k - t ig h tn e s s of fu e l e le m e n ts . A r e p o r t on th is te ch n iq u e w as p u b lish e d in "A to m n a y a E n e r g iy a " , J a n u a r y , 1962. I w ou ld l ik e to know w h e th e r th i s m e th o d i s b e in g u s e d in th e U n ite d S ta te s .

T . S . E L L E M A N : V a r io u s m e th o d s á r e u s e d f o r f u e l - e l e m e n t le a k d e te c tio n : g r o s s g a m m a a s s a y of th e co o la n t, g a m m a a s s a y of s p e c if ic

These proceedings.


f i s s io n - p r o d u c t p h o to p e a k s , d e la y e d n e u tro n c o u n tin g , e t c . T h e a p p l ic a b i l i ty o f e a c h m e th o d d ep e n d s upon th e p a r t i c u la r o p e ra tin g c o n d itio n s of th e r e a c to r . One m e th o d we have in v e s tig a te d fo r d e tec tin g le a k s in w a te r - co o led r e a c to r s i s b a s e d on th e r e m o v a l of f is s io n -p ro d u c t iod ine f ro m th e c o o la n t b y ex c h an g e w ith io d in e in s o lid s i l v e r io d id e fo llo w ed by a s s a y of th e s i l v e r io d id e b e d . F o r a g a s -c o o le d r e a c t o r , c o l le c t io n a n d a s s a y of th e f i s s io n g a s d a u g h te r s sh o u ld b e a s a t i s f a c to r y m e th o d .

P . C . A EBERSO LD : W ith r e g a rd to D r. Y ash in ’s q u es tio n on th e m o n ito r in g of fu e l e le m e n t r u p tu re by m e a s u r e m e n t of f is s io n - p ro d u c t r e le a s e , I know th a t g r o s s f i s s io n - p r o d u c t r e l e a s e i s c h e c k e d a s a r o u t in e m a t te r in an y a i r o r w a te r e ff lu en t f ro m r e a c to r s , an d d e la y e d n e u tro n s ca n a ls o b e u se d fo r th is p u rp o se . W hat so lid d a u g h te rs o f f is s io n g a s e s do you th in k w ould be m o s t su ita b le fo r m o n ito rin g fo r fu e l-e le m e n t fa i lu re ?

T .S . E L L E M A N : T h a t w ou ld d ep en d on th e t im e r e q u i r e d f o r a s s a y , th e s e n s it iv i ty n eed ed , th e lo c a tio n of th e t r a p in th e co o lan t loop an d o th e r f a c to r s r e la te d to r e a c to r o p e ra tio n . A ny iso to p e hav ing r e a d i ly d e te c ta b le g a m m a r a y s , s u c h a s th e LaWD d a u g h te r of Bal40 an d Xei40 t. c o u ld b e s u i ta b le .

P . T E M P U S : I am n o t a r e a c to r m a n bu t I c a n s a y th a t in th e DIO RIT h e a v y w a te r r e a c to r in S w itz e r la n d th e m o n ito r in g of f u e l- e le m e n t r u p tu r e b y u s in g th e d a u g th e r p r o d u c ts o f n o b le g a s e s i s a r o u t in e p r o c e d u r e .

P . C . A E B E R S O L D : W hich o n e s ?P . TEM PU S: A ll I know is th a t the daugh ter f is s io n p ro d u c ts a r e w ashed

out of th e coo ling w a te r by m e a n s of h e liu m , an d c o l le c te d on an e le c tro d e . T he a c tiv ity of th e d ep o s ite d d augh ter p ro d u c ts is th en m e a s u re d in a sp e c ia l c h a m b e r.

SOME RECENT APPLICATIONS OF SHORT H ALF-LIFE RADIOISOTOPES IN AUSTRALIA

J. S. W ATTAUSTRALIAN ATOM IC ENERGY COM MISSION RESEARCH ESTABLISHM ENT,

LUCAS HEIGHTS, NEW SOUTH WALES, AUSTRALIA

Abstract,— Résumé — Аннотация — Resumen

SOME RECENT APPLICATIONS OF SHORT HALF-LIFE RADIOISOTOPES IN AUSTRALIA. This paper

describes the use of short-lived radioisotopes in some of the field investigations recen tly carried out by the Isotope Division of the A ustralian A tom ic Energy Commission.

A radioisotope technique is being developed to trace a ir m ovem ents in clouds, princ ipa lly for use in experim ents related to cloud seeding. In a series of ten experim ents, various quantities up to 2 с o f copper-64 as finely p a rticu la te CuO have been released from an a ircraft and traced by de tecting , with a large crystal sc in tillom eter, the у -rays em itted by the CuO distributed about the aircraft. A novel feature of the m ethod is th a t, not only is the am ount of rad ioactiv ity about the aircraft m easured, but also the d irectional location of the source of radiation. This enables the navigation of the aircraft towards the centre of the radioactiv ity .

A technique is being developed for la rge-sca le ventila tion and air pollution studies. Sm all amounts of copper-64, either as CuO powder or as copper adsorbed on particles, would be released and collected on filter paper using a high-speed air sampler. Experiments show that excellen t discrim ination against natural airborne radioactivity is obtained by using y -y coincidence techniques for detecting the copper-64 positron annihilation pair. The m inim um detection level is about 1 x 10-18 с Сим / с т 8 of air.

A method for detection of leaks in town gas distribution systems is described. About 500 pc of bromine-82 labelled m ethyl bromide is used to test for leaks in the individual services between the gas main and meter, and a feature of the m ethod is that most of the radioactive gas is withdrawn after the test and can be used again.

Finally, experim ents are briefly described in which gold-198 was used to trace silt, effluent and w ater m ovement.

QUELQUES APPLICATIONS RECENTES DES RADIOISOTOPES A COURTE PÉRIODE EN AUSTRALIE. L'auteu r d écrit diverses recherches au m oyen des radioisotopes à courte période entreprises récem m en t par la Division des isotopes de la C om m ission australienne de ré n e rg ie atom ique.

On m et au point une m ethode radioisotopique perm ettan t de suivre les m ouvem ents de l 'a i r dans les nuages, principalem ent aux fins d 'expériences de form ation artif ic ie lle de nuages. Dans ce cadre d 'une série de dix expériences, on a lâché d 'u n aéronef diverses quantités de cu ivre-64, sous forme de particu les fines de CuO, d 'une ac tiv ité a llan t jusqu 'à 2 c e t on les a suivies par dé tection , au moyen d 'u n scin tillom ètre à cristal, des rayons gam m a émis par CuO. La particu larité de cette méthode est qu 'elle permet, non seulement de m esurer la rad ioac tiv ité autour de l 'aé ro n ef, m ais encore de dé te rm iner dans quelle d irec tion se trouve la source de rayonnem ents. C ec i perm et à l 'a é ro n e f de nav iguer vers le cen tre de la rad io ac tiv ité .

On m et au point une m éthode app licab le aux recherches sur la ven tila tion e t sur la pollu tion de l 'a i r . De petites quantités de cuivre-64 sous forme de CuO en poudre ou de cuivre adsorbe par des particules seraient libérées par une chem inée e t recueillies sur un papier filtre à l 'a id e d 'un é c h a n ti l lo n n e r d 'a ir fonctionnant a grande vitesse. Les experiences m ontrent q u 'i l est très facile de distinguer la rad ioactiv ité natu relle de l 'a i r si l 'o n u tilise un com pteur à coïncidence y - y pour dé tecte r la paire de gam m as provenant de l 'an n ih ila tio n positon-électron du cuivre-64. Le seuil de détection est d 'environ 1*10-18 c de cuivre-64 par centim ètre cube d 'a ir .

L'auteur décrit égalem ent un procédé de détection des fuites dans les canalisations de distribution du gaz de v ille . On em ploie environ 500 mc de bromure de m éthyle marqué au brom e-82 pour déceler les fuites entre les canalisations principales e t les com pteurs; la pa rticu la rité de ce procédé est que l 'o n peut récupérer la plus grande partie du gaz rad io ac tif après l 'e ssa i e t le réutiliser.

Enfin, l 'au te u r d écrit b rièvem en t plusieurs expériences dans lesquelles on a u tilisé de Гог-198 pour suivre les dép lacem ents des sédim ents, des effluents e t de l 'e a u .

343

344 J .S . WATT

НОВЕЙШИЕ СПОСОБЫ ИСПОЛЬЗОВАНИЯ В АВСТРАЛИИ КОРОТКОЯИВУЩИХ РАДИОИЗОТОПОВ . В статье описи- вается применение короткоживущих радиоизотопов в некоторых областях исследований, проведенных недавно Отделом изотопов Комиссии по атомной энергии Австралии.

Разрабатывается радиоиэотопный метод для наблюдения за движением воздуха в облаках, особенно для использования в опытах» связанных с рассеянием облаков. В серии из десяти опытов были выпущены из самолета различные количества радиоизотопа медь-64 (до 2 кюри) в виде мельчайших частиц СиО и с помощью большого кристаллического сцинтиллометра прослежены у-лучи, испускаемые частицами СиО, распределявшимися около самолета. Новой особенностью этого метода является то, что измерялся не только уровень радиоактивности около самолетов, но и направленное расположение иоточника радиации. Это делает возможным навигацию самолета в направлении центра радиоактивности.

Разрабатывается метод осуществления вентиляции в больших масштабах и изучения загрязненности воздуха. Небольшие количества меди-64 в виде порошка СиО или меди, адсорбированной на частицах, будут выпущены и собраны на фильтровальной бумаге с использованием быстродействующего пробоотборника доя воздуха. Опыты показывают, что превосходным способом обнаружения естественной радиоактивности в воздухе является использование методов Y-Y совпадений для обнаружения аннигиляции поэитронной пары меди-64. Уровень минимального обнаружения составляет около 1*10"хв кюри меди-64 в 1 см3 воздуха.

Описывается метод обнаружения утечек в системах распределения газа в городах. Для контроля утечек в отдельных службах между газовой магистралью и измерительным прибором используется около 500 милликюри бромистого метила, меченного бромом-82; особенность этого метода состоит в том, что большая часть радиоактивного газа удаляется после испытаний и может быть использована снова.

Наконец, кратко описывается использование золота-198 для наблюдения перемещений наносов эффлюентов и воды.

ALGUNAS RECIENTES APLICACIONES DE LOS RADIOISÓTOPOS DE PERÍODO CORTO EN AUSTRALIA. La m em oria describe e l em pleo de radioisótopos de período corto en algunas de las investigaciones sobre e l terreno que recientem ente ha realizado la División de Isótopos de la Comisión de Energía Atómica de Australia.

Se esta estudiando una técnica radioisotópica para seguir los desplazamientos del aire en las nubes; dicha té cn ica se em pleará p rincipalm ente en experim entos sobre siem bra de nubes con sustancias que provocan la lluvia. En una serie de diez experim entos, se lanzaron desde un avión cantidades de hasta 2 с de cobre-64 en forma de CuO finam ente dividido, cuyo desplazam iento se observó detectando con un contador de centelleo de cris ta l de grandes dim ensiones las radiaciones gam m a em itidas por e l CuO distribuido en tom o a l avión. Una novedad de l m étodo consiste en que n o tó lo mide la radiactividad, sino tam bién la dirección en que está situada la fuente de radiaciones. Esto perm ite o rien tar a l avión h a c ia e l foco de la rad iactiv idad .

Se está estudiando una técn ica para investigar la contam inación de l aire y métodos de ven tilación en g ran esca la . Para e llo , se liberarán pequeñas cantidades de cobre-64 , sea en forma de polvo de CuO o de cobre adsorbido en partícu las, y se recogerán en papel de filtro , u tilizando un aparato para tom ar muestras de aire a gran velocidad. Los experim entos dem uestran que se logra una discrim inación perfecta con respecto a la radiactividad natural del aire em pleando técnicas de coincidencia y -y para detectar e l par que se produce por la aniquilación positrón-electrón de l cobre-64. La concentración m ínim a detectab le es de l orden de los 1 • 10"18 с de cobre-64 por cm 3 de aire.

Se describe un m étodo para lo c a liza r escapes de gas en la red de distribución urbana. Los escapes en ram ales individuales entre la tubería principal y e l contador se detectan con unos-500 pe de bromuro de m etilo m arcado con brom o-82, y una peculiaridad del m étodo es que perm ite recuperar casi todo e l gas radiactivo para volver a u tilizarlo .

Por ú ltim o , se describen brevem ente experim entos en los que se u tilizó oro-198 como indicador para sedim entos, efluentes y m ovim iento de aguas.

1. G EN ER A L INTRODUCTION

La-te in 1960 a " s e l f - s e r v ic e fa c ili ty " fo r ra d io is o to p e p ro d u c tio n w as in s ta l l e d in th e A u s tr a l ia n A to m ic E n e rg y C o m m is s io n (AA EC) r e s e a r c h r e a c to r HIFAR (High F lu x A u s tra lia n R e a c to r) , and fo r the f i r s t tim e a supp ly o f s h o r t - l iv e d r a d io is o to p e s b e c a m e r e a d i ly a v a ila b le in A u s tr a l ia . It

SHORT HALF-LIFE RADIOISOTOPES IN AUSTRALIA 345

b e c a m e p o s s ib le to c a r r y out m any of th e t r a c e r t e s t s w hich had p re v io u s ly b ee n im p r a c t ic a b le ow ing to th e p ro h ib it iv e e x p e n se of a i r - f r e ig h t in g s u f f ic ie n t am oun ts of th e ra d io iso to p e to A u s tr a lia . S ince lo c a l p ro d u c tio n b e gan, s h o r t- l iv e d ra d io iso to p e s have been u se d in 33 t r a c e r te s t s . In a s im il a r p e r io d p r i o r to lo c a l p ro d u c tio n , on ly th r e e t e s t s w e r e u n d e r ta k e n .

T h e Iso to p e D iv is io n of, th e AAEC h as b een a c tiv e ly a s s is t in g o th e r o r g a n iz a tio n s to c a r r y out in d u s t r ia l and f ie ld t r a c e r e x p e r im e n ts , an d th is p a p e r d e s c r ib e s so m e of th e w o rk u n d e r ta k e n in th e l a s t tw o y e a r s .

2. A RADIOISOTOPE TECHNIQUE F O R TRACING AIR M O V E M E N T S IN C L E A R AIR A N D IN C L O U D S

2. 1. In tro d u c tio n

T h e D iv is io n of R ad io p h y sic s of th e CSIRO is c a r ry in g out cloud seed ing e x p e r im e n ts in an a t te m p t to in c r e a s e th e r a in f a l l in c e r ta in a r e a s of A u s tr a l ia . S ilv e r io d id e , th e se e d in g su b s ta n c e , is r e le a s e d in th e fo rm of s m a l l p a r t i c l e s f ro m a i r c r a f t in to 'c lo u d s . L i t t le i s known abou t i t s m o v e m e n t and d is p e r s io n a f te r r e l e a s e . Of p a r t i c u la r i n t e r e s t i s how m u c h of th e se e d in g su b s ta n c e r e a c h e s th e s u b - f r e e z in g te m p e r a tu r e le v e ls w h e re i t m a y a c t a s an ic e n u c le a tin g ag e n t le a d in g to th e fo rm a tio n o f l a r g e ic e c r y s ta ls and su b seq u en tly r a in . T he so lu tion of th is p ro b lem could m a te r ia lly a ffec t th e seed ing p ro c e d u re s a t p re s e n t being em ployed.

A ra d io iso to p e tech n iq u e is being developed bo th to a tta c k th is p ro b le m and to m ak e o th e r fu n d am en ta l s tu d ie s of a i r m o v e m en t in c lo u d s [1] .

2 . 2 . R a d io a c tiv e t r a c e r te ch n iq u e

T he rad io a c tiv e t r a c e r is r e le a s e d fro m an a i r c ra f t and, d u ring a s e r ie s of p a s s e s , th e y - r a y s em itte d by th e m a te r ia l about th e a i r c ra f t a r e d e tec ted by a l a r g e c r y s ta l s c in t i l lo m e te r . F ro m m e a s u re m e n ts o f -y -ray in te n s ity , th e m o v e m e n t of th e t r a c e r m a y b e fo llo w ed and in fo rm a tio n o b ta in e d on i t s s p a t ia l d is t r ib u t io n .

T h e re a r e tw o m a in p rob lertíá ' A sso c ia te d w ith t r a c e r te c h n iq u e s in c lo u d s :

(a) In fo rm a tio n ob ta ined on th e sp a tia l d is tr ib u tio n of th e t r a c e r is l im i te d to m e a s u r e m e n ts a lo n g th e l in e o f f lig h t. B e tw e e n s u c c e s s iv e p a s s e s by th e a i r c r a f t l a r g e ch a n g e s in s p a t ia l d is t r ib u t io n m a y o c c u r and c o n s e q u e n tly a d e ta i le d p ic tu r e of i t s c h a n g e w ith t im e c a n n o t b e o b ta in e d .'

(b) As the rad io iso to p e d is p e rs e s in the a tm o sp h e re , a i r c u r re n ts sw eep i t aw ay f ro m th e p o in t of r e le a s e and so as tim e p a s s e s it b ec o m e s in c r e a s in g ly d if f ic u lt to find th e r a d io a c t iv i ty . In c lo u d s th e t r a c e r m a y b e l o s t c o m p le te ly w ith in a s h o r t p e r io d .P ro b le m (a) i s a fundam en ta l l im ita tio n not only fo r a rad io iso to p e techn ique b u t a ls o fo r m o s t o th e r t r a c in g te c h n iq u e s . I t a p p e a r s f e a s ib le to s o lv e p ro b le m (b) by u s in g d ir e c t io n a l d e v ic e s d u r in g th e p á s s to h e lp lo c a te th e d ir e c tio n f ro m th e a i r c r a f t of th e bu lk of th e ra d io is o to p e , and hen ce m ake i t p o s s ib le to g u id e th e a i r c r a f t b a c k to w a r d s i t on th e s u b s e q u e n t p a s s .

346 J .S . WATT

2 .3 . R a d io is o to p e and f lig h t te c h n iq u e

2.3.1. Radioisotope

C o p p e r - 64, in th e fo rm of f in e ly -p o w d e re d c o p p e r ox id e , w as u se d as th e t r a c e r m a te r i a l fo r m o s t o f th e f lig h t e x p e r im e n ts . T h e c o p p e r ox ide in a se a le d s i l i c a am poule w as d ir e c t ly i r r a d ia te d in th e A u s tra lia n r e a c to r H IF A R . A c tiv it ie s o f up to 30 с a t a s p e c if ic a c t iv i ty of 6 с / g a r e r e a d i ly a v a i la b le . C o p p e r-6 4 h a s a h a l f - l i f e o f 12.8 h , and a lth o u g h e m it t in g few 7 - r a y s d i r e c t ly , i t e m its p o s i t r o n s , r e s u l t in g in 38 0.51 M eV 7 - r a y s p e r 1 0 0 d is in te g r a t io n s .

2. 3. 2. Detection equipment

T h e 7 - r a y s w e re d e te c te d by a s c in t i l lo m e te r , w ith th e s c in t i l la t io n h ea d m oun ted beh ind th e ta i lp la n e . T h e p h o sp h o r w as a c y lin d e r o f so d iu m io d id e of 4 in d ia m . and 3 in h e ig h t. P u ls e s f ro m th e p h o to m u ltip lie r w ere a m p lif ie d , sh a p e d to u n ifo rm h e ig h t and c o n s ta n t w id th and th e n r e c o rd e d on m a g n e tic ta p e . A ll p u ls e s c o rre sp o n d in g to e n e rg ie s above about 30 keV w e r e r e c o r d e d . T h e ta p e s w e re l a t e r p la y e d b a c k in th e l a b o r a to r y .

In th e l a s t f lig h t a p ro to ty p e " d i re c t io n in d ic a to r" w as u se d to in d ic a te w h e th e r th e bu lk of th e r a d io a c t iv i ty w a s to th e le f t o r to th e r ig h t o f th e a i r c r a f t d u r in g a p a s s , so h e lp in g to lo c a te th e r a d io a c t iv i ty w ith r e s p e c t to th e a i r c r a f t . I t c o n s is te d of tw o s c in t i l la t io n h e a d s s e p a r a te d by a le a d sh ie ld w hich w as m oun ted in th e a i r c r a f t in a v e r t i c a l p la n e p a r a l le l to th e f lig h t a x is . T h e ou tpu ts f ro m each head w ere fed in to s e p a ra te r a te - m e te r s . T h e r a t e - m e te r o u tp u ts w e re m ix e d and th e d if fe re n c e ap p lied to a c e n tr e - z e r o r e c o r d e r . T h e le a d s h ie ld w as of s u f f ic ie n t th ic k n e s s to a b s o rb m o s t o f th e c o p p e r - 64 7 - r a y s , so th a t e a c h d e te c to r e ffe c tiv e ly v iew ed opposing h e m is p h e r e s . W hen th e r e w as m o r e r a d io a c t iv i ty to th e r ig h t th a n to th e le f t o f th e a i r c r a f t d u r in g a p a s s , th e d if fe re n c e in c o u n t - r a te s of th e d e t e c to r s w ou ld c a u s e a d e f le c tio n in d ic a t in g th e h ig h e r a c t iv i ty s id e .

2. 3. 3. Release of radioisotope

T h e CuO w as r e le a s e d d u rin g fligh t by u sing e le c tr ic d e to n a to rs to sm a sh th e s i l ic a am poule when t r a i l in g behind th e a i r c ra f t . B efo re th e fligh t a P y r e x g la s s tu b e , co n ta in in g CuO in th e s i l i c a am poule and tw o d e to n a to rs bonded in to th e tu b e by a b r i t t l e r e s in , w as s e c u re ly c lam p e d beh ind th e ta ilp la n e . W ire s fro m th e d e to n a to rs p a s se d th ro u g h a p ipe in to the a i rc ra f t . T he clam p w a s r e le a s e d d u r in g f lig h t, and th e tu b e w as d raw n aw ay f ro m th e a i r c r a f t by th e s l ip s tr e a m . W hen tr a i l in g about 30 ft behind the a i r c ra f t the d e to n a to rs w e re exp loded by an e le c t r i c a l p u lse , so sm a sh in g th e am poule and r e l e a s in g th e p o w d er.

2. 3. 4. Navigation

T h e flig h t p a th w as ch o sen so th a t(a) It w as p o s s ib le to r e tu r n to th e po in t of r e le a s e w ith in tw o m in u tes;


(b) T h e a i r c r a f t 's d ir e c tio n of fligh t d u rin g ea ch p a s s w as along a lin e p a r a l le l to th e d ir e c tio n fo r th e f i r s t p a s s .V isu a l m a rk e r s w e re u se d so th a t the a i r c r a f t could be r e tu rn e d to th e p o s it io n w h e re th e ra d io is o to p e w as l a s t d e te c te d . F o r t r a c in g e x p e r im e n ts in c l e a r a i r , th e a c tu a l p o s it io n of r e le a s e of th e ra d io iso to p e w as m a rk e d by a s m o k e p u ff. S in ce th e p u ff w a s v is ib le fo r on ly a few m in u te s , a n o th e r one w as f i re d on e a c h su b se q u en t p a s s . F o r cloud s tu d ie s a sm o k e puff w as f i r e d ju s t a f te r th e a i r c r a f t e m e rg e d fro m th e cloud .

2 . 4 . S e n s itiv e vo lum e and s e n s it iv i ty of th e tech n iq u e

F o r u n ifo rm c o n c e n tra t io n s o f c o p p e r - 64 in th e a tm o s p h e re , b o th th e vo lum e about th e sc in til la tio n c ry s ta l fro m w hich m o st of the d e tec ted 7 - r a y s w e re e m itte d and th e d ilu tio n s w hich could be q u an tita tiv e ly m e a su re d , w ere d e te rm in e d . E x p e r im e n ts w e re m a d e to m e a s u r e th e co u n tin g r a t e o f th e s c in t i l la t io n d e te c to r a s a .fu n c tio n o f d is ta n c e b e tw e en i t and a c a l ib r a te d c o p p e r -6 4 s o u r c e . B o th s o u r c e and d e te c to r (the s a m e a s u se d in th e a i r c r a f t ) w e re su sp e n d ed f ro m and be tw een to w e rs m o re th a n 100 ft above g ro u n d le v e l so a s to re d u c e in te r fe re n c e f ro m th e g round .

T h e r e s u l t s a r e show n in F ig . 1. T h e o rd in a te i s co u n tin g r a t e X (d is t a n c e ^ and i s n o rm a l iz e d to 1 a t d is ta n c e z e ro . T h e c o l l im a te d b e a m a b s o r p t io n fo r 0 .51 MeV 7 - r a y s in a i r [2] i s g iv e n fo r c o m p a r is o n . T h e d if fe re n c e betw een th e two c u rv e s in d ic a te s a la rg e bu ild -up of 7 - r a y s , in itia lly

DISTANCE FROM SOURCE TO DETECTOR (f t )

Fig. 1

V ariation of coun t-ra te as a function o f d istance betw een source and detector

348 J . S. WATT

of e n e rg y 0.51 M eV, but w hich have been s c a tte re d by th e a i r and so d eg ra d ed in en e rg y . T h e s c in ti l lo m e te r shou ld be p a r t ic u la r ly se n s itiv e fo r d e te c tio n o f th is com ponen t b e c a u se of i t s h igh e ff ic ien c y fo r lo w -e n e rg y 7 - r a y s and b e c a u s e i t d e te c ts in d iv id u a l q uan ta r a th e r th a n d o s e - r a te .

T h e s e n s i t iv i ty of th e a i rb o rn e tr a c in g te ch n iq u e can be d e te rm in e d by n u m e r ic a l in te g ra t io n f ro m F ig . 1. T h is show s th a t th e s c in t i l lo m e te r w ill r e c o r d a c o u n t- r a te of about -70 cps above background when in a i r con tain ing a u n ifo rm c o n c en tra tio n of 30 ццс of C u 64/f t3 . T h is c o u n t-ra te is su ffic ien tly g r e a t e r th a n b a c k g ro u n d (u su a lly 40 to 100 c p s ) fo r q u a n tita tiv e m e a s u r e m e n ts to b e m a d e . S in ce i t i s p o s s ib le to h an d le and r e l e a s e a t l e a s t 2 0 с C u 64, th e u p p e r l im i t of v o lu m e th ro u g h o u t w hich m e a s u r e m e n ts of r a d io is o to p e c o n c e n tra t io n ca n be m ad e i s a t l e a s t 4 m ile 3 .

I t c a n a l s o b è c a lc u la te d f ro m F ig . 1 th a t , i f th e Cu64 0 i s u n ifo rm ly d is p e r s e d , th e n 50% of th e d e te c te d r a d ia t io n c o m e s f ro m w ith in a s p h e re o f r a d iu s 520 f t w ith th e d e te c to r as i t s c e n tr é , and 75% co m es f ro m w ith in a s p h e re of r a d iu s 820 ft.

2 .5 . F lig h t r e s u l t s

R a d io a c tiv ity w as r e le a s e d d u rin g te n fligh t e x p e r im e n ts and th roughou t th e s e r i e s te c h n iq u e s w e re o f te n ch a n g e d an d im p ro v e d . In th e f i r s t tw o f lig h ts , 80 m e q u an titie s of x e n o n -133 w ere u se d . S ubsequently , when s h o r tliv e d ra d io iso to p e s b ec am e a v a ila b le , co p p e r-6 4 a s CuO w as u se d , and w as

Fig. 2

'*“4Record of variation of gam m a-jay intensity along flight path


r e l e a s e d in q u a n ti t ie s f ro m 90 m e to 2 c . In one f lig h t 190 m e Си&Ю w as r e le a s e d in c le a r a i r and t r a c e d fo r a p e r io d of 50 m in . W hen 1 -c q u an titie s of C u640 w e re r e le a s e d in c l e a r a i r , q u a n tita tiv e m e a s u re m e n ts of s p a t ia l d is t r ib u t io n w e re u s u a lly g a in ed fo r p e r io d s of 30 to 35 m in . T h e d e te c tio n p e r io d w as s h o r te r fo r t r a c in g w ith in c lo u d s .

Two fligh t r e c o rd s , show ing th e v a r ia tio n of d e te c te d ra d ia tio n in te n s ity a s th e a i r c r a f t p a s s e d th e ra d io is o to p e , a r e show n in F ig . 2. T h e f i r s t r e c o rd i s fo r an e x p e r im e n t in w h ich th e ra d io is o to p e w as r e le a s e d in c l e a r a i r , and th e p ea k counting r a te f o r th e p a s s m in a f te r r e le a s e w as g re a te r th a n 5000 c p s . .P e a k counting r a t e s d u rin g th e f i r s t few p a s s e s a f te r r e le a s e of 1 -c am ounts of Cu640 w ere u su a lly betw een 5000 and 10 000 cp s . H ow ever, fo r r e l e a s e w ith in a c lo u d , th e p ea k coun ting r a t e s w e re f a r le s s , e . g. th e se c o n d r e c o r d sh o w s th a t th is i s on ly 400 c p s fo r a p a s s m in a f te r r e l e a s e . T h e m a in r e a s o n s fo r th is w e re th a t:

(a) T h e b u lk o f th e r a d io is o to p e , h a v in g b e e n sw e p t by a i r c u r r e n t s aw ay f ro m th e p o in t o f r e le a s e , w as no t n e a r th e a ltitu d e a t w hich th e a i r c r a f t w as fly ing ; and

(b) T h e c o n c e n tra tio n of c o p p e r - 64 w as s m a lle r in clouds th a n in c le a r a i r owing to th e m o re r a p id d is p e rs io n .T h e f o r m e r i s th e m a in r e a s o n fo r th e lo w e r c o u n t - r a t e found so o n a f te r r e l e a s e .

F ro m F ig . 2 i t c a n be s e e n th a t th e b a c k g ro u n d w as abou t 40 c p s . B e tw e e n th e a l t i tu d e s of 1500 and 4000 ft o v e r th e o c e a n i t w as u s u a lly f ro m 40 to 100 c p s , and c o n s ta n t a t an y one a l t i tu d e fo r th e d u ra t io n o f th e e x p e r im e n t .

T h e f lig h t r e c o r d fo r th e te s t , o f th e p ro to ty p e " d i r e c t io n in d ic a to r" i s g iv en in F ig . 3; fo r th is one p a s s , a v e r y d e f in ite in d ic a tio n w as g iv en th a t th e bu lk of th e r a d io is o to p e w as to th e r ig h t o f th e a i r c r a f t .

Fig .3

Flight record of "d irection indicator"

F ig u re 4 show s th e " d is p e rs io n " o f c o p p e r-o x id e , a s a function of t im e a f te r r e le a s e , fo r a f lig h t on 16 M ay, 1961. " D is p e rs io n " i s defin ed a s th e le n g th of f lig h t p a th c o rre sp o n d in g to th e d is ta n c e b e tw een th e p o in ts on the f lig h t r e c o r d w h e re th e c o u n t - r a te , a f te r b a c k g ro u n d h a s b e e n s u b tr a c te d , h a s fa lle n to 1 0 % of th e p e a k c o u n t - r a te o f th e p a s s .

350 J .S . WATT

Fig. 4

"Dispersion" as a function of tim e after release

2 . 6 . D is c u s s io n

F ro m F ig . 4, i t can be se e n th a t about 30 m in a f te r r e le a s e of th e C u ^ O , i t s 7 - r a y s w e re d e te c te d th ro u g h o u t 3000 f t o f f lig h t p a th . H o w ev er, so o n a f te r r e le a s e , w hen th e vo lum e co n ta in in g th e ra d io iso to p e shou ld be s m a ll, th e " d is p e rs io n " m e a s u re d w as about 10 0 0 f t, v a ry in g l i t t le in th e f i r s t few p a s s e s . T h e se la rg e ap p a ren t v a lu es of d isp e rs io n , ind icating poor reso lv in g p o w e r o f th e te c h n iq u e f o r m e a s u r e m e n t o f th e d is t r ib u t io n o f C uO a lo n g th e f lig h t p a th , w e re due to la c k of d i r e c t iv i ty of th e d e te c tio n d e v ic e and to th e l a r g e r a n g e of 7 - r a y s in a i r . M uch b e t te r r e s o lv in g p o w er along th e l in e of flig h t m ay b e ob ta ined u s in g a d e te c to r s e n s itiv e only to th o se 7 - r a y s e m itte d w ith in a s m a l l an g le to th e p la n e p e rp e n d ic u la r to th e d ir e c t io n of f l ig h t. T h is im p ro v e d d i r e c t iv i ty m a y be g a in ed by a c o l l im a te d d e te c to r , a s show n in F ig . 5a.

2 . 7 . F u tu re w o rk

T h e e x p e r im e n ts to d a te have e s ta b l is h e d th e f e a s ib i l i ty o f th e r a d io is o to p e - t r a c in g te c h n iq u e and in d ic a te how b e t te r m e a s u re m e n ts of s p a t ia l d is tr ib u t io n m a y b e ob ta in ed . T h e r e le a s e te ch n iq u e h a s b ee n p ro v ed and in fu tu re e x p e r im e n ts 2 0 - c q u a n titie s w ill be r e le a s e d and shou ld be d e te c te d


w hen d is p e rs e d th ro u g h o u t v o lu m es of a t le a s t a few cub ic m ile s . T he p o s it iv e r e s u l t s f ro m th e p ro to ty p e " d i re c t io n in d ic a to r" show th a t i t sh o u ld be p o s s ib le d u rin g a p a s s to lo c a te th e d ire c tio n of th e bulk of th e iso to p e fro m th e a i r c r a f t .

T h e fo llo w in g t h r e e d e te c t io n u n i ts , i l l u s t r a t e d in F ig . 5, h a v e b e e n d e s ig n e d and w ill b e u s e d in f u tu re f l ig h ts :

(a) C o ll im a te d d e te c to r (F ig . 5a): T h is c o n s is ts o f a 4 - in d ia ití. and 3 - in h ig h c y l in d r ic a l s o d iu m - io d id e c r y s t a l s a n d w ic h e d b e tw e e n tw o c i r c u l a r le a d p la te s . T h e r e s o lv in g p o w er of th e ra d io is o to p e te c h n iq u e to m e a s u r e th e sp a tia l d is tr ib u tio n of th e c o p p e r-o x id e is g re a tly im proved by th e sh ie ld ing of th e c r y s ta l so th a t i t " s e e s " only th o se 7 - r a y s a r r iv in g w ith in a sm a ll ang le to th e p la n e p e rp e n d ic u la r to th e fligh t a x is .(b) L a rg e p la s t ic p h o sp h o r d e te c to r (F ig . 5b): T h is i s s e n s i t iv e to 7 - r a y s c o m in g f ro m a l l d i r e c t io n s , and w ill b e u s e d d u r in g th e l a t e r s ta g e o f th e e x p e r im e n t w hen th e is o to p e i s w e ll d i s p e r s e d and th e 7 - r a y in te n s i ty i s to o low fo r m e a s u r e m e n ts w ith th e c o l l im a te d d e te c to r . T h e p h o s p h o r i s c o v e re d w ith a le a d s h e e t abou t 0 .05 ,-in th ic k , w h ich i s s u f f ic ie n t ly th ic k to a b s o rb m o s t o f th e d e g ra d e d e n e rg y 7 - r a y co m p o n en t and so re d u c e th e s iz e of th e s e n s it iv e vo lum e fro m w hich th e d e te c te d ra d ia tio n c o m e s . W ith th e l a r g e p la s t ic p h o sp h o r bo th s ig n a l and b ac k g ro u n d c o u n t - r a te s w ill in c r e a s e . A s in g le ch an n el a n a ly se r w ith a w ide channel w ill be u se d to r e je c t so m e of th e la r g e p u lse s f ro m th e c o sm ic r a y background .(c) " D ir e c t io n in d ic a to r" (F ig . 5c): A n im p ro v e d d ir e c t io n in d ic a to r i s to b e u s e d to in d ic a te w h e th e r th e b u lk o f th e r a d io is o to p e i s a b o v e , b e lo w , to th e le f t , o r to th e r ig h t of th e a i r c r a f t d u r in g a p a s s and so a llow ro u g h d i r e c t io n a l lo c a tio n . I t c o n s is ts of fo u r s c in t i l la t io n h e a d s , e a c h h av in g a 4 - in d ia m . and 3 - in h ig h c y l in d r ic a l p la s t i c p h o s p h o r , s e p a r a te d by le a d p la te s so th a t ea ch one v iew s one q u ad ra n t of a s p h è re . T h e th in le a d sh e e t abou t e a c h d e te c to r is s u f f ic ie n tly th ic k to a b s o rb m o s t of th e d e g ra d e d e n e rg y 7 - r a y s b u t few of th e u n s c a t t e r e d c o p p e r - 64 7 - r a y s . T h is r e d u c e s th e n u m b er of 7 - r a y s w hich, although e m itte d in one q u ad ran t, m ay be s c a t te r e d in to th e d e te c to r of an o th e r qu ad ran t.

Direction of lli^ht

x scintillation heads

(a) Collimated detector (b) Large plastic phosphor (c)~Direction indicator" detector

Fig. 5

Future de tection systems for use in a er ia l tracing experim ents

352 J .S . WATT

3. A R A D IO ISO T O PE T E C H N IQ U E F O R L A R G E -S C A L E V E N T IL A T IO N AND A IR -P O L L U T IO N STU D IES

T h e d i r e c t t r a c e r m e th o d u s in g a rg o n -4 1 and k r y p to n - 85 f o r s m a l l - s c a le v en tila tio n s tu d ie s [3] is w ell e s ta b lish e d . H ow ever, th is m ethod cannot be u se d fo r l a r g e - s c a l e e x p e r im e n ts b e c a u s e of th e p o te n tia l h a z a rd of the a c tiv i t ie s of ra d io iso to p e r e q u ir e d . A new te ch n iq u e , u s in g x e n o n -133, has r e c e n t ly b een d eve loped fo r la r g e - s c a l e s tu d ie s , bu t th e m ethod is d ifficu lt, in v o lv in g th e c o l le c tio n of th e x en o n - 133 in a co ld t r a p , v a r io u s s ta g e s of g as p u r if ic a tio n , and th en in te rn a l counting of th e xenon- 133 in a p ro p o rtio n a l co u n te r [4].

In th e p r e s e n t p a p e r a s im p le m e th o d i s p ro p o s e d in w h ich r e la t iv e ly s m a ll am ounts of rad io iso to p e could be tr a c e d o v e r la rg e vo lu m es. C opper-64 w ould b e r e le a s e d in th e fo rm of a p o w d er, c o l le c te d on f i l t e r p a p e r u s in g an a i r s a m p le r , and coun ted by y-y co in c id e n ce te c h n iq u e s fo r th e p o s it ro n a n n ih ila tio n p a i r . T h is co u n tin g te c h n iq u e i s h ig h ly s e le c t iv e fo r p o s i t ro n e m it te r s [5] , and so good d is c r im in a tio n w ill be ob ta ined betw een c o p p e r -64 and n a tu r a l a i rb o r n e r a d io a c t iv i ty a ls o c o l le c te d on th e f i l t e r p a p e r .

T o d e te r m in e th e s e n s i t iv i ty of th e y-y c o in c id e n c e te c h n iq u e fo r d e te c t io n of c o p p e r -6 4 , e x p e r im e n ts h av e b ee n m a d e u s in g tw o s c in t i l la t io n c o u n te r s , ea ch w ith a I f - i n d ia m . and 1 - in h igh c y l in d r ic a l so d iu m -io d id e c r y s ta l . T h e c r y s ta l s w e re p la c e d a t a d is ta n c e of abou t 1 /8 in a p a r t , and th e s c in t i l la t io n h e a d s w e re s u r ro u n d e d by 4 in o f le a d . T h e s ig n a l f ro m e a c h h e a d w a s a m p lif ie d and th e n fed in to a s in g le c h a n n e l a n a ly s e r w ith a w ide ch an n el w hich accep ted p u lse s co rre sp o n d in g to en e rg ie s fro m 0.41 to 0.65 M eV. T h e o u tp u ts of th e a n a ly s ë r s w e re fed in to a co in c id e n ce u n it of re so lv in g tim e 0.5 us and th e co inciden t counts re c o rd e d w ith a s c a le r . U sing th i s e q u ip m e n t th e b a c k g ro u n d w as found to b e 0 .15 c p m . A lth o u g h l a r g e a i r sam p les , w e re ta k en so a s to ob ta in as m uch n a tu ra l ra d io a c tiv ity as p o s s ib le on th e f i l te r p a p e r , no in c re a s e in background w as de tec ted . The count- r a te p e r цс. of c o p p e r -64 w as 150 c p s . If the lo n g e s t counting p e r io d is tak en to be 10 0 m in , and if th e b ack g ro u n d c o u n t- r a te h a s b ee n a c c u ra te ly d e t e r m ined p re v io u s ly , th e n i t c a n be show n th a t 10'5цс C u64 can be d is tin g u ish ed f ro m b ackground w ith about a 95% s ig n ific an c e le v e l.

F o r la r g e - s c a l e v e n tila tio n s tu d ie s , c o p p e r-o x id e of p a r t i c le s iz e 1 to 3 Ц d iam . would be u se d , but fo r a tm o sp h e ric p o llu tion s tu d ie s co pper would be ad so rb e d onto th e p a r t ic le s , to be tr a c e d . The p a r t ic le s would be co llec ted on f i l te r p a p e r u s in g a h ig h -sp e e d a i r s a m p le r . T h e cubic m e tre s of a i r can b e sa m p le d in about 8 m in w ith a H u rr ic a n e a i r s a m p le r and a G elm an type A M I f i l t e r p a p e r (m o re th a n ,99% of a e r o s o ls of g r e a te r th a n 1 ц d ia m . r e ta in e d ) of 4 - in d ia m . [6 ]. T h e lo w e r d e te c tio n l im i t fo r a 10 m3 a i r sa m p le c o r re sp o n d s to a c o n c e n tra tio n of IX 10" 18 с C u 64/c m 3 a i r (10'S дс in 10m 3). T h u s if 10 m e C u 6 4 jy e re r e le a s e d , i t cou ld be d e te c te d w hen u n ifo rm ly d is p e r s e d th roughou t a cube of s id e 2.2 km . T h is is about 104 t im e s as sen s itiv e as the d ire c t- tra c in g tech n iq u e , u sing k ry p to n -85 [3].

P o te n tia l u s e s fo r th is tr a c in g tech n iq u e a re a tm o sp h e ric p o llu tion s tu d i e s , l a r g e - s c a l e v e n t i la t io n e x p e r im e n ts an d v e r y l a r g e - s c a l e t r a c in g of a i r m ovem en t in th e a tm o sp h e re . R ecen tly th e va lue of the ZnS(Cd) (inactive) t r a c in g te c h n iq u e fo r a b s o lu te m e a s u r e m e n ts o f c o n c e n tra t io n h a s b ee n p la c e d in doiabt by a d i r e c t ly c o m p a r a t iv e e x p e r im e n t w ith x e n o n - 133 [4].


D eta ile d co m p a ra tiv e e x p e r im e n ts fo r ZnS(Cd) and c o p p e r -64 tra c in g te c h n iq u es would be p o ss ib le .

4. LOCATION OF GAS LEAKS IN P IP E S FROM GAS MAINS

G as co m p an y e x p e r ts e s t im a te th a t th e lo s s of g a s th ro u g h le a k s is e q u iv a le n t to b e tw e e n 10 and 207o o f A u s t r a l i a 's g a s c o n s u m p tio n . T h e s e l a r g e l o s s e s e x is t b e c a u s e no s a t i s f a c to r y m e th o d h a s b e e n found f o r lo c a tin g th e le a k s . M ost o f th e g a s lo s s o c c u rs in th e in d iv id u a l s e rv ic e s , th e p ip e betw een th e g a s m a in and c o n s u m e r 's m e te r . T h is p ip e i s of about 1 -in d ia m . , up to 60 ft in le n g th , and is l e s s than 1 ft u n d erg ro u n d , excep t w here i t jo in s th e m a in , u s u a l ly a t a d ep th of fo u r fe e t . T h e g a s p r e s s u r e in th e m a in v a r ie s , but is about 4 p s i . A m ethod is re q u ire d fo r th e ro u tin e checkin g of a l a r g e n u m b e r o f in d iv id u a l s e r v ic e s an d a r a d io is o to p e te c h n iq u e h a s b e e n d ev e lo p e d fo r th is p u rp o s e [7].

T h e in d iv id u a l se rv ic .e p ip e i s d isc o n n e c te d a t th e m e te r and a m ix tu re of to w n g a s an d l e s s th a n 500 juc o f b r o m in e - 8 2 - la b e l le d m e th y l b r o m id e is in je c te d u n d e r p r e s s u r e (see F ig . 6). A p o r ta b le s c in t i l lo m e te r i s p la ce d

Location of gas leaks in pipes

a t g ro u n d le v e l above th e ju n c tio n of p ip e and g as m a in and w hen th e r a d io a c tiv i ty i s d e te c te d th e flow is s to p p e d and a v a lv e a t th e in je c tio n p o in t is c lo se d . If th e r e i s a le a k in th e p ip e th e d ire c tip n of flow w ill r e v e r s e , and by m o v in g a p o r ta b le s c in t i l lo m e te r a lo n g th e g ro u n d ab o v e th e p ip e and d e te c tin g an in c r e a s e in 7 - r a y in te n s ity w h e re th e g a s h a s le a k e d in to th e so il , th e le a k can be lo c a te d to w ith in 6 in . If the p ipe is b u r ie d a t a un ifo rm d e p th in s o i l o f c o n s ta n t d e n s ity , th e ty p e o f g ra p h o f 7 - r a y in te n s i ty a s a fu nction of d is ta n c e along th e p ip e is th a t show n in F ig . 6. A fte r th e t e s t th e g a s in th e p ip e i s w ith d ra w n and ab o u t 90% o f th e m e th y l- b ro m id e i s r e co v e red in a cold t r a p and can be u se d aga in . It is e s tim a te d th a t 50 s e rv ic e s can be te s te d p e r day.

D e ta ils o f th e in je c tio n techn ique a re as follow s:A r e s e r v o i r of m e th y l b ro m id e , in i t ia l ly a t a p r e s s u r e o f 100 p s i , and of a c t iv i ty 30 m e , i s c o n ta in e d in a g a s c y l in d e r . A t e a c h in d iv id u a l s e r v ic e

354 J .S . WATT

to be te s te d , l e s s th a n 500 juc i s t r a n s f e r r e d to a s m a ll g a s c y l in d e r w hich is th e n d isc o n n e c te d . T h is s m a ll c y l in d e r h a s tw o o u tle ts and one of th e s e i s c o n n e c te d to th e in d iv id u a l s e r v ic e a t th e m e te r end . A le a th e r b la d d e r i s f a s te n e d to th e o th e r o u tle t an d th e flow o f to w n g a s f o r c e s th e m e th y l b ro m id e in to th e b la d d e r w h ere th e r e q u ir e d vo lu m e of tow n gas m ix e s w ith th e ra d io a c tiv e g a s . T h e sm a ll cy lin d e r is th e n d isco n n ec ted and a r e v e rs ib le p u m p , p la c e d b e tw e e n th e b la d d e r and th e in d iv id u a l s e r v ic e a t th e m e te r end , f o r c e s th e g a s m ix tu re in to th e p ip e .

F o r r e m o v a l of th e g a s f ro m th e s e r v ic e , th e b la d d e r i s d isc o n n e c te d and re p la c e d by a co ld t r a p (dry ic e and ace tone) in s e r ie s w ith a la rg e s to r age c y l in d e r . T h e pu m p i s r e v e r s e d and a s th e g a s flow s th ro u g h th e co ld t r a p abou t 90% of th e m e th y l b ro m id e i s re m o v e d . It is e s t im a te d th a t th e s a m e co ld t r a p an d s to r a g e c y l in d e r m a y b e u s e d fo r a b o u t 2 0 t e s t s .

5. T R A C IN G O F S IL T , E F F L U E N T AND W A T E R M O V EM EN T USING G O LD - 198

T h e b a s ic te c h n iq u e fo r t r a c in g w a te r flow , u s in g 7 - r a y e m ittin g i s o to p e s and u n d e rw a te r s c in ti l la t io n d e te c to rs , w as developed in 1958 fo r in v e s t ig a t io n s on th e flow p a t te r n s in a p o w e r s ta t io n co o lin g pond [8]. W ith th e advent of lo c a l p ro d u ctio n of ra d io iso to p e s , g o ld -198 has rep la ce d iodine- 131 fo r th is ty p e of t r a c e r t e s t . G o ld -198 is a p a r t i c u la r ly su ita b le iso to p e s in c e h ig h a c t iv i t ie s a r e a v a ila b le a t low c o s t , i t s h a l f - l i f e o f 2 .7 d i s o f th e sa m e o r d e r of t im e a s m o s t of the t r a c e r te s ts r e q u ir e fo r com ple tion , and s in c e by a d s o rp tio n it can be u se d to la b e l so lid m a te r ia ls , su c h as s i l t and sa n d , e tc .

In th e l a s t tw o y e a r s , th e fo llo w in g flow in v e s t ig a t io n s w e re c a r r i e d out by th e A A E C 's Iso to p e s A d v iso ry and C o n su ltin g S e rv ic e [9] in con junctio n w ith o th e r o rg a n iz a tio n s :(a) E ff lu e n t f ro m a p ro p o se d pu lp f a c to ry w ill be d is c h a rg e d in to H o sp ita l B a y , T a s m a n ia . T o d e te r m in e w h e th e r th e e f f lu e n t w ould a c c u m u la te in th e b ay , an in v e s tig a tio n w as m ade of th e w a te r m o v em en t u s in g 5 с Aui98 . T h e w ork show ed th a t th e bay w as se lf - f lu sh in g .(b) D is p e rs a l of h ig h ly -p ro c e s se d sew age effluen t in th e s e a fro m an ou tfall 3000 ft f ro m th e s h o re w as d e te rm in e d u s in g 60 с Aui98 . T h e g o ld - 198 wras c o n tin u o u s ly fed in to th e se w a g e e ff lu e n t o v e r a p e r io d of th r e e d a y s , and w a s t r a c e d u n t i l th e c o r r e s p o n d in g s e w a g e c o n c e n tra t io n w a s w e ll b e lo w th a t c o n s id e r e d to b e a h e a l th h a z a rd .(c) T h e e ff lu en t f ro m a su lp h id e w o rk s in N ew S outh W a le s i s d is c h a rg e d in to a s m a ll c r e e k about 1 m ile u p s tr e a m fro m a t id a l la k e . T h re e h u n d red m i l l i c u r ie s o f g o ld - 198 w as u s e d to t r a c e th e w a te r m o v e m e n t and i t w as show n th a t th e r e w as no b u ild -u p of e ff lu e n t in th e c r e e k .(d) A n in v e s tig a tio n w as m a d e to d e te rm in e th e f e a s ib i l i ty of s e a d is p o s a l of fly a s h s lu r r y f ro m a la r g e p o w e r s ta t io n u n d e r c o n s tru c tio n on th e New S ou th W a le s c o a s t . A s lu r r y , in w h ich 50 c A u 198 w as a d s o rb e d on 100 lb o f fly a s h , w as co n tin u o u sly fed in to th e oceaii o v e r a f iv e -h o u r p e r io d , and in th e s a m e p e r io d 250 t of f ly a s h w as d u m ped o v e r i t f ro m a c o l l ie r . B y fo llo w in g th e g o ld - 198 i t w as found th a t o c e a n c u r r e n t s so o n c a r r i e d th e


fly a s h out to s e a . T h e m a x im u m v o lu m e th ro u g h o u t w hich th e ra d io iso to p e w as d e te c te d w as ab o u t 1 /2 0 m i le 3 (5 m i l e 2 of s u r f a c e a r e a X 60 f t d ep th ),(e) T h e m o v e m en t of s i l t in N e w c a s tle H a rb o u r , New South W ales [10] h a s b een s tu d ied by tra c in g 100 lb of s i l t la b e lle d , by ad so rp tio n , w ith 12 с Auiss. T h e r a d io a c t iv i ty w as t r a c e d fo r 9 d , a f te r w h ich t im e i t h ad s p r e a d o v e r a lm o s t th e e n t i r e 1.5 m i l e 2 bed of th e h a r b o u r .

R E F E R E N C E S

[1] FOOKES, R. A . , WARBURTON, J. A. and W ATT, J. S . , Progress Report on trac ing of Air M ovem entsin c lear Air and Clouds using a radioisotope T echnique, AAEC report TM135 (1962).

[2] R adiological H ealth Handbook, US D ept, o f H ealth , Educ. and W elfare (I960) 144.[3] COLLINS, B. G. and SMITH, D. B. t "The M easurement of ventila tion Rates using a radioactive Tracer",

J. Inst. Heating V entilating Engrs. 23 (1955) 270.[4] EGGLETON, R.E. and THOMPSON, N. ."Loss of fluorescent Particles in atmospheric Diffusion Experiments

by comparison with Radiotracer XenonT Nature 4806 (1961) 935.[5] ANDERS, E . , "On the presence of A l2® in m eteorites and tek tites" , Geochim. e t Cosmochim. Acta 19

(1960) 53.[6] GELMAN INSTRUMENT CO, Dust Topics, G elm an Xnstr. C o . , C helsea , M ich. 1_ 2 (1960) 15.[7 ] BESWICK, С. K . , Private com m unication .[8] GREGORY, J .N . , "Some recent Developments in the Application of radioisotope Techniques in Australia",

Radioisotopes in the Physical Sciences and Industry, I_ IAEA, Vienna (1962) 415.[9] ELLIS, W. R ., BESWICK, С. K. and FISHER, Marion E . , Private communications.

[10] PATTISON, A. e t aL , The Form ulation and Operation of tie ld Experiments using radioactive Isotopes for tracing silt M ovement, Hunter V alley Res. Found. Monograph 7 Sect. 1 and 2 (1961).

D I S C U S S I O N

M. MIRNIK: In co n n e c tio n w ith th e a ir -m o v e m e n t s tu d ie s you d is c u s s in s e c t io n 2 of y o u r p a p e r , I sh o u ld b e in te r e s te d to know how y o u o b ta in m a x im u m A gi d is p e r s io n an d w hat te c h n iq u e you u s e f o r in je c t in g th e A gi in to th e a i r .

J . W A TT: F ro m th e p o in t of v iew of se e d in g e ff ic ie n c y , p a r t i c le s iz e and c r y s ta l s t r u c tu r e of th e su b s ta n c e s e le c te d a r e of p r im a r y im p o r ta n c e . W ith d ry ic e , th e n u m b e r of p a r t i c l e s p ro d u c e d p e r g r a m of d ry m a te r i a l i s f a i r ly l im ite d . S ilv e r io d id e i s u s e d b e c a u s e so m e th in g in th e r e g io n of 1014 p a r t i c l e s a r e r e le a s e d p e r g ra m .

As fo r th e in je c tio n tech n iq u e em ployed , a so lu tion con tain ing p o ta ss iu m io d id e an d s i lv e r n i t r a te i s co n tin u o u sly fed in to a b u rn e r u n d e r th e wing of th e a i r c r a f t and th e s i lv e r iod ide co m es out of th e b u rn e r in the fo rm of v e ry fin e p a r t ic le s .

QUELQUES APPLICATIONS DES RADIOÉLÉMENTS A PÉRIODE COURTE DANS L'INDUSTRIE

GAZIÈRE FRANÇAISE

C. TELLIER GAZ DE FRANCE, PARIS

ETG. COURTOIS ET M. GASNIER

CENTRE D'ÉTUDES NUCLEAIRES, SACLAY, FRANCE


SOME APPLICATIONS OF RADIOISOTOPES OF SHORT HALF-LIFE IN THE FRENCH GAS INDUSTRY. For the purpose o f keeping rubber jointings in old gas piping systems in good condition, certa in hydrocarbides in very weak concentration are injected into the system in the form of aerosols. Bromonaphthalene hydrocarbide lab e lled w ith brom ine-82 is added in order to de te rm ine the re ach o f the aerosols. The quantity of trace r recovered, on filter-paper discs distributed along the system, is determ ined by counting with an end-window counter.

Four m illicu ries of brom onaphthalene sufficed to tra c e th e hydrocarbide over a leng th of 7 km in a conduit 15 cm d iam .

M unicipal gas authorities stipulate a m inim um rate of a ir renewal in dom estic premises. For the purpose of checking this rate, xenon-133 is diffused throughout the premises and the change in concentration is measured by means o f a scin tilla tion counter. Concentrations of the order of 0 .5 m c /m 3 are sufficient. The reproducib ility of results is greatly superior to that obtained with conventional methods.

The princip le o f isotopic m ethods o f leak d e tec tio n is w ell-know n. In order to perfec t these methods for industrial purposes, an experim ental pipeline, 140 m in length and 25 cm d ia m ., was installed underground a t Saclay, a t a depth of 1 .10 m . This pipe has five experim ental leakage points, w ith adjustable discharge, located in d ifferent kinds of soil (sand, chalk , c lay , loca l Saclay earth). The first results obtained with this insta llation are described below.

A descrip tion is given o f pressure tests carried out to check w ater-leak -tigh tness prior to pu tting new conduits in to service. Sodium -24 in th e form of b icarbonate is used as trace r, and d e te c tio n is done from inside the conduit by m eans o f a scraper piston enclosing a se lf-con ta ined G eiger-coun ter m easuring un it and a m ag n e tic recorder.

The d ifficu lties encountered in perfec ting this apparatus are described.The graph obtained after decoding shows a very marked peak for every leak , the position of each being

determ ined to w ithin about 2 m. For easy detection , some 20 дс must escape through the leak.To find leakages in m ains, m ethyl bromide labelled with brom ine-82, prepared on the spot and starting

with Br8-2NH4, is used. A fter in jec tion , the rad ioactive gas is uniform ly m ixed by c ircu la tion . D etection is perform ed from ground le v e l by m eans of portable sc in tilla tio n counters. The trials , w hich are continuing, have already m ade it possible to determ ine the activ ities required and the most favourable schedule for the de tection o f d ifferen t types of leak .

QUELQUES APPLICATIONS DES RADIOELEMENTS A PERIODE COURTE DANS L’INDUSTRIE GAZŒRE FRANÇAISE, Pour assurer la préservation des joints de caoutchouc dans les v ie illes canalisations de gaz, on y in jec te sous forme d 'aérosols certains hydrocarbures à très faible concentration. Pour déterm iner la portée de ces aérosols, on ajoute à l'hydrocarbure du brom onaphtalène m arqué au brom e-82. Ce traceur, recueilli sur des disques de papier filtre disposés le long de la canalisation, est dosé par com ptage au compteur cloche. Q uatre m illicu ries de brom onaphtalène ont perm is de suivre l'hydrocarbure sur 7 km de longueur dans une conduite de 15 cm de d iam ètre .

Le distributeur de gaz de v ille impose un taux m inim um de renouvellem ent d ’air dans les locaux do m estiques. Pour contrôler ce taux, on disperse dans le lo c a l du xénon-133 dont on mesure la concentration en fonction du tem ps au moyen d 'un com pteur à sc in tilla tion . Des concentrations de xénon de l'o rd re de

357

358 C. TELLIER et al.

0 ,5 m c /m 8 conviennent. La reproductibilité des résultats est très supérieure à celle obtenue par l 'em p lo i de méthodes classiques.

Pour m ettre au point à un stade industriel des procédés de détection de fuite par radioisotopes dont le principe est déjà connu, on a installé à Saclay une canalisation expérim entale de 140 m de longueur e t 25 cm de diam ètre, enterrée à 1 ,10 m de profondeur. C ette conduite comporte cinq fuites expérim entales, de débit réglable , situées dans des terrains de natures différentes (sable, c ra ie , arg ile , terre de Saclay). Les auteurs décrivent ci-dessous les prem iers résultats obtenus au moyen de ce tte insta llation .

Pour contrô ler T é tan ch éité lors des essais de pression précédan t la m ise en service d ’une condu ite de transport d 'e a u neuve, ils ont u tilisé le traceu r sodium -24 sous form e de b icarbonate . La d é tec tio n se fa it depuis l ’in te rieur de la conduite au m oyen d*un piston racleur contenant un ensem ble autonom e de mesures à com pteur de Geiger e t un enregistreur m agnétique.

Ils décrivent les difficultés rencontrées lors de la m ise au point de c e t appareillage.Le diagram m e obtenu après décodage fait apparaître un pic très visible pour chaque fuite qui est dé te r-

m inee à environ deux m ètres. Pour une bonne dé tection , i l faut qu*une vingtaine de m icrocuries sortent par la fuite.

Pour rechercher les fuites de gaz dans des canalisations de distribution, on a u tilisé du bromure de m é - thyle marqué au brom e-82, préparé sur le terra in à partir de *2BrNH4. Après injection , le gaz rad ioac tif est homogénéisé par circulation. La détection est faite depuis le niveau du sol au moyen de compteurs à scin tilla tion portatifs. Les essais, qui se poursuivent, ont dé jà perm is de déterm iner les activ ités à m ettre en je u e t i*horaire le plus favorable pour la détection de différents types de fuites.

НЕКОТОРЫЕ ВИДЫ ПРИМЕНЕНИЯ КОРОТКОЖИВУЩИХ РАДИОЭЛЕМЕНТОВ ВО ФРАНЦУЗСКОЙ ГАЗОВОЙ ПРОМЫШЛЕННОСТИ. В целях обеспечения сохранности каучуковых муфт в старых газовых трубопроводах прибегает к спринцевании некоторыми гидрокарйидами очень слабой концентрации в виде аэрозолей. Чтобы определить стойкость аэрозолей, к гидрокарбиду добавляют меченный бромом-62 бромонафталин. Этот индикатор, собранный на дисках фильтровальной бумаги, расположенных вдоль трубопровода, отсчитан с помощью торцевого счетчика. Четыре милликюри бромнафт&лина позволяют следить за состоянием гидрокарбида в трубе диаметром в 15 см на протяжении 7 км.

Городской распределитель газа устанавливает минимальный коэффициент обновления воздуха в хилых помещениях. В целях контроля за этим коэффициентом в помещении рассеивают ксенон-133, концентрация которого измеряется с учетом времени при помощи сцинтилляционного счетчика. Считаются соответствующими концентрации ксенона порядка 0,5 милликюри/м3 . При таком методе воспроизводимость результатов значительно выше той, которую получают при применении обычных методов.

Чтобы разработать промышленные методы обнаружения утечки при посредстве радиоизотопов, принципы которых ухе известны, в центре Сакле улохили на глубине 1,10 м экспериментальную трубу длиной в 140 м и диаметром в 25 см. На этой трубе имелись 5 экспериментальных отверстий для утечки с регулируемым расходом воды или газа, причем отверстия находились в различных почвах (песок, мел, глина, почва Сакле).

Цель опыта заключалась в том, чтобы проконтролировать под давлением герметичность подготавливаемой для эксплуатации новой трубы. В качестве индикатора был использован натрий-24 в виде бикарбоната. Обнаружение производилось на внутренней стороне трубы. При этом был использован прибор, состоящий из счетчика Гейгера и магнитного регистратора.

Описываются трудности, которые встретились при установке этой аппаратуры.Полученная после расшифровки диаграмма показывает довольно заметный максимум для каждого

случая утечки, которая определяется приблизительно в 2 м. Для проведения достоверного обнаружения необходимо, чтобы с утечкой уходило до 20 мккюри.

Для обнаружения утечки газа в распределительных трубах использовали меченный бромом-62 бромистый метил, приготовленный на месте из Br02NH4 . После впрыскивания радиоактивный газ гомогенизировался путем циркуляции. Обнаружение производилось на уровне земли при помощи портативных сцинтилляционных счетчиков. Испытания, которые еще продолжаются, уже позволили определить необходимую для применения активность и наиболее благоприятные условия для обнаружения различных типов утечки.

ALGUNAS APLICACIONES DE LOS RADIOELEMENTOS DE PERÍQDO CORTO EN LA INDUSTRIA FRANCESA DEL GAS. Para asegurar la preservación de las juntas de goma de las tuberías viejas de gas, se inyectan concentraciones muy bajas de ciertos hidrocarburos en forma de aerosoles. Con objeto de determ inar e l alcance de

APPLICATIONS DES RADIOÉLÉMENTS A PÉRIODE COURTE 359

dichos aerosoles, se añade a l hidrocarburo brom onaftaleno m arcado con brom o-82. Este indicador, que se recoge sobre discos de papel de filtro colocados a lo largo de la tubería, se valoró por recuento en un contador de cam pana. Con 4 m e de bromonaftaleno se ha podido seguir e l hidrocarburo en una tubería de 7 km de longitud y 15 cm de diám etro.

Las compañías de gas imponen un índice m ínim o de renovación del aire en los locales domésticos. Para controlar ese índ ice , en e l lo ca l se dispersa xenón-133, cuya concentración en función d e l tiem po se m ide con un contador de c en telleo . Resultan adecuadas concentraciones de xenón d e l orden de 0, 5 m c /m 3. La reproductib ilidad de los resultados es m uy superior a la conseguida con los m étodos' corrientes.

Para elaborar técnicas industriales de detección de escapes de gas mediante radioisótopos, cuyo principio es ya conocido, se ha instalado en e l Centro de Saclay una canalización experim ental de 140 m de longitud y 25 cm de d iám etro , en terrada a 1 ,10 m de profundidad. Esta tubería tiene cinco escapes experim entales, de caudal g raduable , situados en terrenos de n a tu ra leza d ife ren te (arenoso, c re táceo arcilloso , tie rra de Saclay). A con tinuación se describen los prim eros resultados obtenidos con esta in sta lación .

Se ha realizado un experim ento para com probar la estanqueidad durante los ensayos de presión que se efectúan antes de poner en servicio una tubería nueva. Se ha u tilizado com o indicador e l sodio-24 en forma de bicarbonato. La detección se efectúa desde e l interior de la canalización m ediante un pistón raspador que con tiene un conjunto autónom o de m ed ic ión form ado por un con tador G eiger y un registrador m agnético .

En la m em oria se describen las d ificu ltades que ha p lan tead o la construcción de estos aparatos.En e l diagram a obtenido después de la transcripción, puede observarse un m áxim o muy visible.por cada

escape, que ha sido loca lizado con una precisión de l orden de 2 m. Para una buena detección, es necesario que por e l escape salgan unos 20 дс de com puesto radiactivo.

Se han efectuado experim entos con la finalidad de loca liza r los escapes de gas en las canalizaciones de distribución. Se ha em pleado bromuro de m etilo m arcado con brom o-82, preparado in s itu , a partir de l й ВгЫН4. Una vez inyectado, e l gas rad iactivo se hom ogeneiza por circulación . Los escapes se lo ca lizan a ras de tierra m ediante contadores de cen telleo portátiles. Los ensayos, que se prosiguen realizando, han p e rm itido determ inar las actividades que han de em plearse y e l horario más favorable para detectar los diferentes tipos de escape.

IN TR O D U CTIO N

D epuis 1957, l ' i n d u s t r i e g a z iè re f r a n ç a is e a u t i l i s é le s r a d io é lé m e n ts a r t i f ic ie l s d an s le s c a s où le s m é th o d es c la s s iq u e s don n aien t des r é s u l t a t s in c o m p le ts ou peu s a t i s f a i s a n ts ou p a s de r é s u l t a t s du to u t. N ous c i te ro n s d an s un o r d r e ch ro n o lo g iq u e q u a tre d es a p p lic a tio n s r é a l i s é e s .

I. M ARQUAGE D ' UNE H U ILE DE BRUM ISAGE

L e s jo in ts de caoutchouc des v ie i l le s c a n a lisa tio n s de d is trib u tio n , gonflés p a r le s h y d ro c a rb u re s a ro m a tiq u e s que con tena it le gaz de houille, son t d e s s é c h é s e t r a c o rn is p a r le s gaz que l ’on d is tr ib u e m a in ten an t e t qui en sont exem pts . On re m é d ie à c e t in convén ien t en a jo u tan t c e r ta in s p ro d u its ch im iq u es (hydro c a r b u r e s , eau , e tc .) ; c e t te o p é ra tio n e s t ap p e lé e « co n d itio n n e m en t du g a z » . L o rsq u e le s c o rp s c h o is is son t ad d itio n n és au gaz à d es d o se s s u p é r ie u re s à la s a tu ra tio n (cas d es h u ile s lo u rd e s ) , i l s s ’y p ré se n te n t so u s fo rm e de b ro u illa rd . Le cond itionnem en t e s t a lo r s un « b ru m is a g e » . L 'é m is s io n de b ro u illa rd d 'h u i le se fa it en deux te m p s: a) v a p o risa tio n de l 'h u i le dans une f r a c t io n du gaz ch au ffée , b) in tro d u c tio n de c e tte d e r n iè re dans le r e s t e du gaz r e s t é f ro id . L ' a é ro s o l p ro d u it , v é h ic u lé p a r le gaz , s e d ép o se s u r le s tu y aux e t l e s jo in ts , j u s q u 'à un e c e r ta in e d is ta n c e de la s ta t io n d 'é m is s io n , qui dépend beau co u p de la d im e n s io n d e s g o u tte le tte s d 'h u i le é m is e s . C e tte d is ta n c e e s t ap p e lé e « p o r té e du b ro u i l la rd » . E lle c o n s titu e un bon c r i t è r e

360 C. TELLŒR et al.

p o u r c o m p a re r 1' e f f ic a c i té d e s d if fé re n ts ty p e s d 1 a p p a r e i ls de b ru m is a g e s u s c e p t ib le s d 1 ê t r e e m p lo y é s , c a r s e u le l a f r a c t io n de l 'h u i l e liq u id e r e c o u v ra n t l e s jo in ts im p ré g n e e f f ic a c e m e n t c e u x -c i , l a f r a c t io n a r r iv a n t à l e u r c o n ta c t u n iq u e m e n t so u s fo rm e de v a p e u r é ta n t in s u f f is a n te .

P o u r ju g e r de l a p o r té e , i l fa u t d is p o s e r d 'u n e m é th o d e d e d o sa g e ne s ' ap p liq u an t q u 1 à l 'h u i l e liq u id e en su sp e n s io n d an s le gaz e t non à l 'h u i l e p o u rsu iv a n t son ch em in so u s fo rm e de v a p e u r . C e tte m éth o d e do it ê t r e su ff is a m m e n t p r é c i s e e t s u r to u t s e n s ib le au x f a ib le s t e n e u r s d 'h u i l e , p u is - q u 1 e l le e s t e m p lo y é e c o m m e m e s u r e d e z é r o .

A. M é th o d e s c l a s s iq u e s

1. Il e x is te une m éthode ra p id e d 'a p p r é c ia t io n qui c o n s is te à re c e v o ir , s u r une ro n d e lle de p a p ie r f i l t r e , un je t du gaz à ex a m in e r, p a s sa n t à t r a v e r s un o r i f i c e c a l ib r é p e n d a n t un te m p s donné e t à u n e p r e s s io n que l 'o n m e s u r e . On f a i t une le c tu r e du d ia m è tre de la ta c h e d 'h u i le ob tenue qui donne un o r d r e de g ra n d e u r de la q u a n tité d 'h u i l e r e c u e i l l i e . M a lh e u re u s e m e n t, s i c e t te m é th o d e donne u n o r d r e d e g r a n d e u r de l a p o r té e du b r o u i l l a r d , e l le e s t , p a r c o n tre , t r è s ap p ro x im ativ e , peu s e n s ib le e t peu re p ro d u c tib le .

2. U ne a u t r e m é th o d e c o n s is te à f a i r e p a s s e r u n v o lu m e d é te r m in é de gaz p en d a n t 5 à 6 h à t r a v e r s une c a r to u c h e D u rieu x , à e x t r a i r e e n su ite l 'h u i l e p a r l 'a c é to n e d a n s u n a p p a r e i l S oxh let e t en fin à p e s e r c e tte h u ile a p r è s é v a p o ra tio n de 1 'a c é to n e d a n s u n e c a p s u le a n t ig r im p a n te . C e tte m é th o d e e s t a s s e z p r é c i s e , m a is t r o p lo n g u e .

On en v ie n t to u t n a tu re l le m e n t à 1 ' id é e de m a r q u e r l 'h u i l e p a r un c o r p s r a d io a c t i f e t de m e s u r e r 1' a c t iv i té de la ta c h e d 'h u i l e s o u s un c o m p te u r « c lo c h e » .

B . M é th o d e fo n d é e s u r l a r a d io a c t iv i té : t r a ç a g e p a r l e b r o m e - 8 2

1. Choix du radioélément et sécurité

L a co n d u ite é tu d ié e devan t r e s t e r en s e rv ic e , on se do it n a tu re lle m e n t d 'u t i l i s e r un é m e tte u r de c o u r te p é r io d e . E n o u tre , le t r a c e u r d o it e n t r e r d a n s l a c o m p o s itio n de p ro d u i ts o rg a n iq u e s s u s c e p t ib le s d e s e d is s o u d re d an s l 'h u i l e de b ru m is a g e e t de la su iv re e ff ica ce m en t. C e tte d e rn iè re cond itio n s ig n if ie n o ta m m e n t que le t r a c e u r u t i l i s é do it a v o ir un po in t d 'é b u l l i t io n a u s s i v o is in p o s s ib le du p o in t d 'é b u l l i t io n de l 'h u i l e de b ru m isa g e . O r, l e s h u ile s de b ru m is a g e so n t d iv e r s e s , m a is e l le s so n t to u te s r e la t iv e m e n t lo u r d e s e t e l l e s o n t d e s p o in ts d 'é b u l l i t io n m o y e n s v o is in s d e 300°C .

L e b ro m o n a p h ta lè n e m a rq u é au 82Br ({joint d 'é b u ll i to n : 281°C), c o rp s dont l a s y n th è s e e s t f a c i le , s ' e s t a v é r é le m e i l le u r t r a c e u r que 1' on a i t pu e n v is a g e r .

Il im p o r te d 'a u t r e p a r t que la co n c e n tra tio n en 82Br chez l 'a b o n n é r e s te in f é r ie u re à l a c o n c e n tra tio n m a x im a a d m is s ib le qui e s t de 0,1 цс/тп3 d 'a i r (« d o s e p o p u la tio n » ). E n f a is a n t le c a lc u l p o u r l 'a b o n n é le p lu s ex p o sé qui b r û le 200 m g d 'h u i l e p a r m è t r e cu b e d e g az u t i l i s é , ta u x r e te n u p o u r le b r u m is a g e , e t en su p p o s a n t qu e l à d ilu t io n d a n s 1' a i r d e l a c u is in e de l 'a b o n n é e s t a u m o in s s u p é r ie u r e à un f a c te u r 8, on o b tie n t u n e a c t iv i té


de 4 m e de 8 2 g r p a r k ilo g ra m m e d 'h u i le m is en œ u v re , a c t iv i té qu i a é té u t i l i s é e .

L e s e x p é r ie n c e s d é c r i t e s d a n s c e t te c o m m u n ic a tio n e u r e n t l i e u s u r une conduite ex p é r im e n ta le longue de 10 km , de d ia m è tre 150 m m ,éq u ip ée à son d é p a r t d ' un a p p a re il de b ru m isa g e p ré a la b le m e n t r é g lé s u r un débit co n s ta n t

2. Méthodes de détection

P lu s ie u rs m éth o d es de d é tec tio n fu re n t u til is é e s :a) E n tê te de la condu ite , le dépôt d 'h u i le é ta i t su ff isa m m e n t im p o r ta n t

p o u r que l 'o n p u is s e su iv re la c a n a lisa tio n avec un d é te c te u r p o r ta t if à sc in t il la t io n . C es m e s u re s m o n trè re n t que le gaz p e rd a it une p a r t ie a p p ré c ia b le de son b r o u il la rd au début de son p a rc o u rs . Il e x is te sa n s doute dans l 'a é r o so l d e s g o u tte le tte s p lu s g r o s s e s qui ont te n d an c e à se d é p o s e r ra p id e m e n t.

b) U n s y s tè m e d e p r é lè v e m e n t de g az fu t e s s a y é . I l c o n s is ta i t à f a i r e b a r b o te r le gaz d an s un so lv a n t t e l que le d ioxane qui d e v a it d is s o u d re to u t le b ro m o n a p h ta lè n e . L e b a rb o ta g e s 'a v é r a in s u f f is a n t p o u r c a p te r to u t le t r a c e u r .

c) E n d é f in itiv e , le s y s tè m e de p ré lè v e m e n t a d o p té é ta i t c o n s t i tu é de deux p a r t i e s m é ta lliq u e s p e rm e tta n t de s e r r e r t r è s ex a c tem e n t une ro n d e lle de 20 m m d e d ia m è t re . L ' é ta n c h é i té é t a i t a s s u r é e p a r un jo in t to r iq u e en c a o u tc h o u c sy n th é tiq u e e t p a r u n r a c c o r d à p o s e r a p id e . L e g a z p r é le v é d an s la c a n a l is a t io n p a s s e e n t iè r e m e n t à t r a v e r s le p a p ie r f i l t r e e t y d é p o se 95%* de l 'h u i l e en su sp e n s io n (fig . 1).

VERS AIR LIBRE

Appareil de prélèvem ent de brouillard, a) Vue éc la tée de l ’appareil de dosage; b) Appareil en position sur la canalisation.

* Ce chiffre a é té vérifié en disposant un tube contenant plusieurs rondelles de papier filtre à la suite de l ’appareil décrit ci-dessus. D’autre part la forme du tube très court am enant le gaz sur la rondelle filtran te est sans influence notable. On l*a vérifié en orientant son o rifice am ont en diverses directions dans la conduite principale.


L e s r o n d e l le s de p a p ie r f i l t r e é ta ie n t e n s u ite c o m p té e s au c o m p te u r « c lo c h e » , le ta u x de co m p tag e ob tenu devan t ê t r e p ro p o rtio n n e l à la q uan t i t é d 'h u i le déposée .

3. Sensibilité de la détection

S upposons que le b r o u i l la rd d 'h u i le c e s s e d 'ê t r e e ff ic a c e l o r s q u ' i l ne r e s t e p lu s d an s le gaz que 1% du b r o u i l la rd in it ia l . Il e s t fa c ile de v o ir que l e s a c t iv i té s c h o is ie s p e r m e t te n t de d é te r m in e r ce p o in t, m ê m e av e c d e s p r é lè v e m e n ts d e g az a u s s i f a ib le s que 100 1. E n e f fe t, c e s 100 1 c o r r e s ponden t a lo r s à 0,2 m g d 'h u i le , ce qui donne 30 d é s in té g r a t io n s /s . L 'e f f i c a c i té du c o m p te u r p o u r la g é o m é tr ie ad o p tée é ta n t v o is in e de 30%, le s ig n a l e s t de 540 c h o c s /m in , f a c ile m e n t m e s u ra b le av e c g ra n d e p r é c is io n (la p r é c is io n s ta t is t iq u e (j(N )/N e s t é g a le à 2% p o u r un c o m p ta g e d u r a n t c in q m in u te s ) .

E n r é a l i t é , d e s p h é n o m è n e s a n n e x e s so n t in te rv e n u s qu i o n t re n d u la m e s u r e c i - d e s s u s to u t ju s te p o s s ib le .

C. C o n s id é ra t io n s s u r le m a rq u a g e d 'u n b r o u i l la r d e t a p p lic a tio n au c a s du b r u m is a g e

1. Création d'un brouillard

D ans le c a s d 'u n m a rq u a g e de b ro u i l la rd , l e s c o n c e n tra tio n s r e la t iv e s de l 'é l é m e n t de b a s e e t de l 'é l é m e n t m a rq u e u r ne son t p a s le s m ê m e s dans le s g o u tte le tte s du b ro u il la rd e t dans la p h ase liqu ide qui a s e rv i à le c r é e r . E n effet: le gaz v e c te u r re ç o i t p0 g ra m m e s du co n s titu an t de b a se p a r m è tre cu b e . L a te n s io n de v a p e u r s a tu r a n te F 0 de c e c o n s t i tu a n t c o r r e s p o n d à un p o id s m 0 g ra m m e s p a r m3 de gaz à la t e m p é r a tu r e t . Ce c o n s titu a n t de b a s e e s t lu i-m ê m e m a rq u é en p h a s e liq u id e à un e c o n c e n tra tio n x i de t r a c e u r av an t in je c tio n , de te n s io n de v a p e u r s a tu ra n te Ft à la te m p é r a tu re t , c o r re s p o n d a n t à un p o id s de t r a c e u r de m t g ra m m e s p a r m è tr e cube de gaz.

L e p o id s Po de J ' é lém e n t de b a s e se fra c tio n n e en deux p a r t ie s : m j qui p a s s e en p h a s e v a p e u r e t p g q u i r e s t e s o u s f o r m e d e g o u t te le t te s . On a:

p 0 = m 0+ P g .

E n ap p e lan t x la c o n c en tra tio n que p ren d , à 1' é q u ilib re , le t r a c e u r dans le s g o u tte le tte s d e .1 'a é ro so l, de m êm e le poids p0x i de t r a c e u r se frac tio n n e en deux p a r t ie s : m tx en p h ase v ap e u r (loi de R aoult) e t pgx en ph ase liqu ide. On a:

PoXj = m, x + pgx .

П s ' e n su it que:

x = ____Pflïl___Po + (m t - m o)

L a te n e u r x n ’e s t donc é g a le à x i que s i l e s te n s io n s * de v a p e u r

* Pour au tan t que les masses m olécu laires ne soient pas trop éliognées.


du c o n s t i tu a n t de b a s e e t du t r a c e u r , à la t e m p é r a tu r e c o n s id é r é e , so n t r ig o u r e u s e m e n t é g a le s . Si Ft > F 0 , x < x e e t in v e r s e m e n t .

E n fin , r e m a rq u o n s q u 'u n e fo is l 'é q u ilib re é ta b li e n t r e le s g o u tte le tte s d 'a é r o s o l e t la p h a se g a z e u se , se u le une v a r ia t io n de co m p o sitio n de l 'u n e d e s d eux p h a s e s p e u t e n t r a în e r u n e v a r ia t io n de c o m p o s it io n de 1' a u t r e . A in s i l a d is p a r i t io n so u s f o rm e de d é p ô t d 'u n e p a r t i e de l a p h a s e l iq u id e n e m o d if ie r a p a s l a t e n e u r en t r a c e u r d a n s l e s g o u t te le t te s r e s t a n t e s .

2. Application au brumisage

A la t e m p é r a tu r e de 10°C, à la q u e lle e u re n t l ie u l e s e x p é r ie n c e s , l a te n s io n de l 'h u i l e é ta it n ég lig eab le devant ce lle du b ro m o n ap h ta lèn e qui é ta it de 0,01 m m Hg c o r re s p o n d a n t à 0,125 g /m 3 de gaz; p0 é ta n t ég a l à 0 ,200 g, la fo rm u le du p a ra g ra p h e p ré c é d e n t d ev ien t

0,2 x , ' „ r ” ----- ----- J— = 0,615 x x.0,2 + 0,125

Ce p o in t a é té v é r if ié e x p é r im e n ta le m e n t en fa is a n t p a s s e r le gaz , im m é d ia te m e n t a p r è s le b r u m is e u r , s u r une c a r to u c h e D urieux , p en d an t c inq h e u r e s , de fa ç o n que la q u a n tité d 'h u i l e s o i t s u f f is a n te p o u r ê t r e e x t r a i te p a r le p ro c é d é S oxh le t. P a r co m p ta g e , la q u a n tité d 'h u i l e p ré v u e é ta i t de 19,4 m g; p a r e x t ra c t io n , on t r o u v a i t 32 m g . D ' où le r a p p o r t x /x j = 0,6 j06, t r è s v o is in du c h i f f r e 0 ,615 p ré v u p a r l a th é o r ie .

M a is , c o n tra ire m e n t, à la th é o r ie , l e s r é s u l t a t s donnés p a r la m éth o d e fondée s u r la r a d io a c tiv ité e t l 'e x t r a c t e u r S oxhlet, ont m o n tré que la te n e u r en p ro d u it r a d io a c t i f d an s le s g o u tte le tte s d im in u a it au fu r e t à m e s u re que l a d is ta n c e à la s ta t io n d 'é m i s s i o n a u g m e n ta it , c ' e s t - à - d i r e au f u r e t à m e s u r e que la q u a n tité de b r o u i l la rd p a r m 3 de gaz d im in u a it (fig . 2). C eci p ro u v e que l a p h a s e v a p e u r , p o u r u n e r a i s o n q u e lc o n q u e , s ' a p p a u v r i t e n t r a c e u r to u t au long du p a rc o u rs , le s g o u tte le tte s de b ro u il la rd devan t a lo r s « d i s t i l l e r » du b ro m o n a p h ta lè n e p o u r r é ta b l i r 1 'é q u ilib re , ce qui d im inue x. C ec i p eu t ê t r e ex p liq u é p a r l 'u n e d e s deux h y p o th è se s s u iv a n te s qui n 'o n t d 'a i l l e u r s p a s é té c o n trô lé e s :

a) A b so rp tio n s é le c tiv e de b ro m o n ap h ta lè n e p a r le s dép ô ts p ré e x is ta n ts s u r le s p a r o is de la c a n a lis a t io n e t qui n 'a v a ie n t p a s p ré c é d e m m e n t é té m is en é q u ilib re av ec du b ro m o n ap h ta lè n e in a c tif .

b) Le p ro c é d é de fa b r ic a tio n du b ro u il la rd n 'a s s u r e p a s aux g o u tte le tte s une ta i l le u n ifo rm e . C om pte te n u de la te n s io n c a p i l la ir e , la te n e u r en t r a c e u r d an s le s g r o s s e s g o u tte le tte s en é q u ilib re avec le gaz n ' e s t p a s f o r c é m e n t la m ê m e que c e l le d a n s l e s g o u tte le t te s t r è s f in e s . L ' a é r o s o l p e r d p lu s v ite s e s g r o s s e s g o u tte le tte s que le s f in e s , d 'o ù u n e v a r ia t io n p o ss ib le de x.

C e tte d é c ro is s a n c e de x en fonction de la d is ta n c e d im inue la s e n s ib ili té de l a m é th o d e e t r e n d l e s in te r p r é ta t io n s q u a n t i ta t iv e s d e s r é s u l t a t s p lu s d if f ic i le s .

D. R é s u l ta ts

L a m éthode ' de d o sa g e é ta n t b ie n é ta b lie , on a pu c o n s ta te r que la p o r té e p r a t iq u e du b r o u i l l a r d é t a i t d e 7 k m e n v iro n s u r l a c a n a l i s a t io n é tu d ié e .

364 С. TELLER et al.

X

—

/\\\

\\

//

/0,50 0.Ю0 0,150 0,200

TENEUR DU GAZ EN HUILE IN g / m 3

Figure 2

Courbe de la teneur donnée par la m éthode radioactive en fonction de la teneur réelle'.

Q u an t à la d é c r o is s a n c e de l a t e n e u r en b r o u i l l a r d en fo n c tio n d e l a d is ta n c e au po in t d 'é m is s io n , e lle e s t l in é a i re a p rè s une chute b ru sq u e pour le s p r e m ie r s 200 m (fig . 3), l e s d o sa g e s é ta n t to u s e ffe c tu é s aux h e u re s de p o in te* , cf. ta b le a u I.

On a a u s s i v é r i f ié que, lo r s q u e le s ta c h e s d 'h u i le so n t b ie n v is ib le s , le com ptage n e t s u r une ta c h e e s t p ra tiq u em e n t une fonction lin é a ire du c a r r é de son d ia m è tre .

S ig n a lo n s en fin que, d an s la p ra tiq u e du d o sa g e , i l e s t bon d 'u t i l i s e r la r é t r o d if fu s io n d e s j3 du b ro m e p a r 1 m m de p lo m b , ce qui a u g m e n te le c o m p ta g e de 30%.

E . C o n c lu s io n

C e tte e x p é r ie n c e m o n tre que, s i le p r in c ip e du m a rq u a g e e s t s im p le , la d ifficu lté de t r o u v e r un t r a c e u r adéquat oblige à une m ise au po in t p a rfo is d é l ic a te . N éan m o in s, g râ c e aux é lé m e n ts à c o u r te p é rio d e , on a pu u t i l i s e r un t r a ç a g e r a d io a c ti f de l 'h u i l e du gaz sa n s in te r ro m p re la d is tr ib u tio n aux ab o n n és, to u t en r e s p e c ta n t d e s r è g le s t r è s s t r i c t e s de s é c u r ité .

* Ce m om ent est le plus favorable car i l donne la portée m axim ale e t il suffit qu'un jo in t a it été im prégné pendant l'heure de pointe pour rester protégé.


Figure 3

Evolution du brumisage le long de la canalisation.

TABLEAU I

RÉSULTATS OBTENUS P A R LA M É T H O D E FONDÉE SUR LA RADIOACTIVITÉ

Numéro du posteDistance au

poste d 'ém ission (m )

Teneur du gaz en huile (m g/m s)

1 0 200

2 200 120

3 800 110

4 1200 105

5 2600 80 ,

6---L.....

7000 19

II. ÉTU D E DE LA V ENTILATIO N DE LOCAUX DOMESTIQUES

L 1 é tu d e de la v e n t i la t io n d e s b â t im e n ts i n t é r e s s e 1' in d u s t r ie du g az , d 1 a b o rd au p o in t de vue de l 'h y g iè n e p u b liq u e , m a is a u s s i au p o in t de vu e d e s d é p e r d i t io n s th e r m iq u e s , do n t l a c o n n a is s a n c e p e r m e t le c a lc u l d e s p u is s a n c e s à in s ta l l e r . P o u r c h i f f r e r p ré c is é m e n t l 'im p o r ta n c e de la v e n t i la t io n , on d é f in it un « ta u x h o r a i r e de r e n o u v e lle m e n t d 'a i r » R, r a p p o r t


e n t r e l e v o lu m e d 1 a i r d e r e n o u v e lle m e n t a p p o r té p a r h e u r e d a n s l e lo c a l e t l e v o lu m e de ce lo c a l .

A. M é th o d e s c l a s s iq u e s

L a v e n t ila tio n d e s lo c au x , d é jà é tu d ié e d ep u is lo n g te m p s p a r d 'a u t r e s o rg a n is m e s o f f ic ie ls i n té r e s s é s p a r l 'h y g iè n e pu b liq u e , a s u s c i té de n o m b re u x t r a v a u x . . P a r m i l e s m é th o d e s c la s s iq u e s , c ito n s :

a) L a m é th o d e th e rm iq u e : on m e s u re l 'a p p o in t de c h a le u r n é c e s s a i r e p o u r e n t r e te n i r d a n s le lo c a l une t e m p é r a tu r e d o n n ée . On c a lc u le l e s d é p e rd it io n s c a lo r if iq u e s d 'a p r è s le s te m p é r a tu re s de p a ro i m e s u ré e s e t l 'o n e n d é d u it R, en s u p p o sa n t que l a d if fé re n c e e n t r e l a d é p e rd i t io n to ta le e t l e s p e r t e s p a r le s p a r o is c o n s titu e l a p e r te th e rm iq u e due à la v e n tila tio n . L a p r é c is io n e s t t r è s m a u v a is e .

b) Le t r a ç a g e ch im iq u e in a c tif : d an s un p r e m ie r p ro c é d é , on in tro d u it d an s 1' a tm o s p h è re du lo c a l du g az c a rb o n iq u e dont on su it la c o n c e n tra tio n (co m p te te n u du g az c a rb o n iq u e e x p iré p a r l e s o cc u p an ts ), d é te rm in é e p a r a n a ly se ch im iq u e où p a r s p e c tro m é tr ie in fra ro u g e . D ans un second p ro céd é , on in tro d u it un e q u a n tité donnée d 'h y d ro g è n e , p u is on su it l a c o n c e n tra tio n d e c e c o rp s p a r m e s u r e de la c o n d u c tib ilité th e rm iq u e du m é la n g e gazeux . On p e u t a u s s i u t i l i s e r l 'h é l iu m (m e s u r e s au p e t i t s p e c t r o m è tr e de m a s s e ) . B ien que l a p r é c is io n ne so it p a s m a u v a is e , on c o n s ta te que l e s r é s u l t a t s o b te n u s n e so n t p a s to u t à f a i t r e p r o d u c t ib le s .

C e t te r e v u e d e s p r o c é d é s e x i s ta n ts e x p liq u e q u ' on s e s o i t o r ie n té v e r s l 'e m p lo i de t r a c e u r s r a d io a c t i f s , m é th o d e à la q u e lle on t f a i t ap p e l CADIERGUES e t LEVEQUE d ès 1950 e t 1951 (1, 2], en u til isa n t le xénon-133.

B. M éthode p a r t r a ç a g e ra d io a c tif à co u rte pério d e

1. Choix du traceur radioactif

N o tre bu t e s s e n t ie l n ' é ta i t p a s de c o n n a ître le s c o u ra n ts de convection e t le ta u x de r e n o u v e l le m e n t lo c a l , m a is s a m o y e n n e d a n s 1 ' e n s e m b le du vo lum e o b se rv é . Le gaz t r a c e u r deva it donc av o ir un rayonnem en t su ffisa m m e n t d u r (gam m a); i l d ev a it de p lu s:

a) p o s s é d e r un e v is c o s i té dynam ique v o is in e de c e lle de l 1 a i r de façon à o b te n ir ra p id e m e n t le m e il le u r m é lan g e p o ss ib le ;

b) a v o ir u n e p é r io d e s u f f is a m m e n t lo n g u e p o u r p e r m e t t r e une e x p é r i m e n ta t io n s a t i s f a i s a n te to u t e n é v i ta n t u n e c o n ta m in a tio n d u ra b le ;

c) en fin , p o u v o ir ê t r e ob tenu avec une a c tiv i té su ff isa n te , à un p r ix de r e v ie n t a c c e p ta b le .

P o u r de t e l l e s m e s u r e s , n o u s a v io n s le' ch o ix e n t r e l e x én o n -1 3 3 , le b r o m u r e de m é th y le m a r q u é a u b r o m e - 8 2 , l 'a r g o n - 4 1 , le k ry p to n -8 5 e t l e r a d o n - 222, d é jà u t i l i s é s p a r n o s p r é d é c e s s e u r s . N ous a v o n s c h o is i le x é n o n -1 3 3 .

2. Appareil de détection

N o u s a v io n s le ch o ix e n t r e l e s a p p a r e i l s su iv a n ts :a) C h a m b re d 'io n is a t io n : p o u r to u s le s t r a c e u r s é m e t te u r s a lp h a ou


b ê ta , la ch a m b re d 'io n is a t io n e s t un d é te c te u r u ti l is a b le . T ous le s ray o n n e m e n ts é m is c o n tr ib u a n t à la m e s u re e t le b r u i t de fond é ta n t b a s , la s e n s i b i l i té d e l a m e s u r e e s t b o n n e e t p e r m e t d 'u t i l i s e r d e s a c t iv i té s s e n s ib le m e n t p lu s b a s s e s que c e l le s qu i so n t n é c e s s a i r e s p o u r l e s a u t r e s m o d e s de d é te c tio n . P a r c o n tre , la c h a m b re d 'io n is a t io n n ' e ffec tu é l a m e s u re que s u r son vo lum e in té r ie u r qui n e peu t d é p a s s e r quelques l i t r e s , e t la s ta b i l i té de s e s in d ic a tio n s e s t d iffic ile à a s s u r e r .

b) D é te c te u r au s u lfu re de zinc: p o u r d é te c te r le r a d o n - 222, é m e tte u r a lpha, on peu t f a i r e c i r c u le r le gaz à a n a ly s e r dans un b a llo n s u r le s p a ro is d u q u e l e s t d é p o sé du s u lf u r e d e z in c ; le b a llo n lu i - m ê m e e s t p o s é s u r u n p h o to m u ltip lic a te u r . Ce m ode de d é te c tio n a l l ie aux av a n ta g e s de l a d é te c tio n p a r c h a m b re d 'io n i s a t io n u n e b o n n e s ta b i l i t é e t un b a s b r u i t d e fond . M a lh eu reu sem en t le s d é tec tio n s p o rten t, com m e c e lle s de la ch am b re d 'io n isa tio n , s u r un fa ib le vo lum e de gaz.

Ce m ode de d é tec tio n a é té u t i l is é p a r l 'u n d 'e n t r e nous [3] pou r évaluer, en m e s u ra n t le ta u x de r e n o u v e lle m e n t d 'a i r , 1' e f f ic a c i té d 'é v e n tu e ls r i deaux d 'a i r d e s t in é s à r e m p la c e r .des p o r te s c la s s iq u e s , de m a n iem en t d if f ic i le , d an s de g ra n d s e n tre p ô ts f r ig o r if iq u e s .

c) C o m p te u r G e ig e r -M û lle r e t d é te c te u r à s c in ti l la t io n : s i l e t r a c e u r e s t un é m e tte u r g am m a, i l e s t p o s s ib le d 'u t i l i s e r un d é te c te u r à s c in t i l l a tio n . C eci p e rm e t d ' i n t é r e s s e r un vo lum e t r è s g ran d (le vo lum e de l a p iè c e é tu d ié e d a n s n o tr e c a s ) e t d 'é v i t e r l e s e r r e u r s d u e s aux c o u ra n ts d e c o n v e c tio n . D ' a i l l e u r s en ra p p ro c h a n t le s in d ic a t io n s d 'u n d é te c te u r à s c in t i l l a t io n e t d 'u n c o m p te u r G e ig e r -M ü l le r du ty p e « c lo c h e » , on p e u t s e r e n d r e co m p te de l ' im p o r ta n c e de c e s c o u ra n ts e t m e s u r e r s i n é c e s s a i r e un ta u x d e re n o u v e lle m e n t lo c a l . Vu s e s a v a n ta g e s , ce m o d e de d é te c tio n a é té ad o p té e t le x é n o n - 133 a é té c h o is i co m m e t r a c e u r .

3. Allure des courbes expérimentales obtenues

L e re n o u v e lle m e n t de l ' a i r p a r v e n tila tio n n a tu re l le d an s l e lo c a l s u it un e lo i de la fo rm e

y = y o e "Rt

où y0 e s t la c o n c en tra tio n de 1' a i r in it ia l dans 1' a i r se tro u v a n t dans la: p ièce au te m p s t e t R le ta u x de ren o u v e llem en t d 'a i r p réc éd em m en t défin i.

C e tte fo rm u le qui p e rm e t l 'e x p lo ita t io n de g rap h iq u es s e m i- lo g a r i th m iques, su p p o se e n tre a u t re s , que R e s t constan t, que là co n c en tra tio n in it ia le en t r a c e u r e s t hom ogène e t que le m élange de 1' a i r d 'a p p o r t avec 1' a i r e x is ta n t se fa it in s tan ta n ém e n t.

L 'u t i l i s a t i o n d 'u n d é te c te u r à s c in t i l la t io n a t té n u e f o r te m e n t l 'e f f e t d e s é c a r t s s e p ro d u is a n t en r é a l i t é p a r r a p p o r t à c e s h y p o th è s e s .

4. Conduite des expériences et résultats

L e s e x p é r ie n c e s ont é té a p p liq u é e s à la m e s u re du ta u x de re n o u v e lle m e n t d 'a i r d an s une p iè c e de 8 m 3 (fig . 4), à v e n tila tio n c ro is é e ( le s o u v e rt u r e s d 'a é r a t i o n é ta ie n t p r a t iq u é e s d a n s d e s c lo is o n s n e s e t r o u v a n t p a s v is - à - v is l 'u n e de l 'a u t re ) , en p a r t ic u lie r , lo rsq u e d es a p p a re ils à gaz é ta ie n t en fonctionnem ent ( nous d isp o s io n s dans la p ièce d 'u n ch au ffe -eau de 125mth).

368 C. TELLffiR et al.

AERATION HAUTE

1GEIGER-MULLER TYPE CLOCHE

AERATIONBASSE

SCINTILLATEUR

OVENTILATEUR

PORTE

COUPE DE LA PIECE *

R= 0.015

TOh 10t(HEURES)

UNITES ARBITRAIRES

x. = 9310 x2= 9170

ESSAI O'ÉTANCHÉITÉ a)

MESURE DE R EN VENTILATION NATURELLE b)

Figure 4

Méthode radioactive pour mesure de ven tila tion .

P o u r d es locaux de ce tte d im ension , l 'e x p é r ie n c e p récéd em m en t acquise a v a it m o n tr é que d e s a c t iv i té s de 5 m e p a r o p é ra tio n é ta ie n t s u f f i s a n te s .

C e tte a c t iv i té de x é n o n -133 é ta i t a p p o r té e d an s une am p o u le de v e r r e . A p rè s b r i s de 1' am poule dans le m ilieu de la p iè ce e t b ra s s a g e de 1' a i r pour hom o g én éisa tio n d u ran t dix m in u tes , on a p ro cé d é aux m e su re s su iv an te s lo r s de chaque op éra tio n :

a) D é te rm in a tio n de 1' é ta n c h é ité de la p iè c e en m e s u ra n t le tau x de r e n o u v e lle m e n t d 'a i r de la p iè c e f e rm é e . E n g é n é ra l , l e s d é fa u ts de 1 'é ta n c h é ité c o r re s p o n d a ie n t à un ta u x de re n o u v e lle m e n t R v o is in de 0 ,02, -donc n é g lig e a b le .

b) M e s u re du ta u x d e r e n o u v e l le m e n t R s im u lta n é m e n t au c o m p te u r G e ig e r - M ü l le r e t a u d é te c te u r à s c in t i l la t io n au c o u r s d 'u n e a é r a t io n en v e n t ila tio n c r o is é e . C es e x p é r ie n c e s ont donné d e s r é s u l t a t s f id è le s e t r e p ro d u c tib le s av ec le d é te c te u r à s c in ti l la t io n , qu i a p e r m is de p r é c i s e r la d e u x iè m e d é c im a le du ta u x de r e n o u v e l le m e n t g lo b a l (R = 2 ,28 ), b i e n q u e le c o m p te u r G e ig e r -M ü l le r m e tte en év id en c e d 'im p o r ta n te s v a r ia t io n s de c o n c e n tra tio n s lo c a le s c o r re s p o n d a n t à un ta u x de r e n o u v e lle m e n t R lo c a l o sc illa n t e n tre 1 e t 2,5. R appelons que le d é te c te u r à sc in tilla tio n fo u rn is sa it un ta u x de re n o u v e lle m e n t m oyen s u r to u te la p iè c e , a lo r s que le co m p teu r G e ig e r -M ü lle r o p é ra it s e u le m e n t s u r un vo lum e d 'e n v iro n un l i t r e . Ce d e r n ie r c o m p teu r p e rm e t de d é te rm in e r 1' e f f ic a c ité du b r a s s a g e e t de lo c a lis e r le s zones m o r te s .


c) M e su re du ta u x de re n o u v e lle m e n t R, une fo is le ré g im e du ch au ffe - eau a tte in t. L e s m e s u r e s ( s c in til la tio n s ) donnent un ta u x de re n o u v e lle m e n t R = 7,12 en a c c o rd avec le s r é s u l t a t s d es m é th o d es c la s s iq u e s (R = 8). Q uant à la s é c u r i té , on s a i t que la d o se m a x im a a d m is s ib le p o u r le xénon-133 e s t de 4 -10 -6c /cm 3 , so it 4 m c /m 3 . I l n 'y a donc là aucun p ro b lè m e .

Q. C onclusion

L e s m e s u re s du ta u x g lo b a l de re n o u v e lle m e n t de 1' a i r d an s un lo c a l, e f fe c tu é e s s u r le ra y o n n e m e n t g am m a du xéno n -1 3 3 av ec un a p p a re il la g e à s c in t i l la t io n , f o u rn is s e n t d e s d o n n ée s p r é c i s e s e t r e p r o d u c t ib le s . N ous c o n se il lo n s de r é s e r v e r le com ptage b ê ta p o u r la m e s u re du tau x de re n o u v e lle m e n t lo c a l. C es m é th o d es ont l 'a v a n ta g e d 'ê t r e a p p lica b le s dans to u te s l e s c i r c o n s ta n c e s e x p é r im e n ta le s , c e qui n ' e s t p a s l e c a s d e s m é th o d e s b a s é e s s u r u n d o sa g e du g az c a rb o n iq u e .

III. R E C H E R C H E DE F U IT E S D ' EA U OU DE GAZ SUR DESCA N A LISA TIO N S E N T E R R É E S

L e p r in c ip a l o b je c tif d e s r e c h e r c h e s g a z iè re s en m a t iè r e de fu ite s e s t la d é tec tio n d es fu ite s de gaz dans le s r é s e a u x de d is trib u tio n . La re c h e rc h e d es fu ite s en p h a se liq u id e in té r e s s e cependan t a u s s i l ' i n d u s t r i e du gaz c a r l e s c a n a l is a t io n s de t r a n s p o r t de gaz so u s h au te p r e s s io n su b is s e n t, avan t m is e en s e r v ic e , u n e é p re u v e de r é s i s t a n c e m é c a n iq u e à 1' ea u , au c o u r s de la q u e lle to u s le s su in te m e n ts d e v ra ie n t p o u v o ir ê t r e d é te c té s . C e la e s t p a r t i c u l i è r e m e n t d if f ic i le , p a r c e q u e , l o r s de 1 ' é p re u v e h y d ra u liq u e , l a c a n a l is a t io n e s t e n t e r r é e so u s 1 m de r e m b la is .

P o u r m e t t r e au p o in t à un s ta d e in d u s t r ie l d e s p r o c é d é s g é n é ra u x de d é te c tio n de fu i te s p a r r a d io is o to p e s , don t le p r in c ip e e s t d é jà connu , on a in s ta l l é , au C e n tre 'd 1 é tu d e s n u c lé a i r e s de S ac lay , un e c a n a l is a t io n e x p é r im e n ta le .

A. In s ta l la t io n e x p é r im e n ta le

L a c a n a l is a t io n , e n t e r r é e à 1 ,10 m d e p ro fo n d e u r , p r é s e n te 100 m de lo n g u e u r u t i le (138 m av ec l e s g a r e s d e p is to n s r a c l e u r s e t l e s s o r t i e s de so l) e t un d ia m è tre de 250 m m (10"3y4 p o u r le tu b e , 1 2 "3 /4 p o u r le s g a re s ) .

E l le e s t e n t e r r é e d a n s q u a t r e t e r r a i n s d i f f é r e n ts ( c r a ie , t e r r e a r g i le u s e de S ac lay , a r g i l e p la s t iq u e , sa b le ) qu i on t é té d a m é s a p r è s l e s t r a v aux (fig. 5). E lle co m p o rte à chaque e x tré m ité une g a re de p is to n s r a c le u r s .

C inq s im u la te u r s de fu ite so n t r é p a r t i s s u r so n p a r c o u r s . Un s im u la te u r de fu ite (fig. 6) co m p o rte un tube d 'a c i e r qui p a r t du fe e d e r , rem o n te au n iv ea u du so l où une d év ia tio n p e rm e t l ' in s ta lla tio n d 'u n r o ta m è tr e ou d 'u n com pte u r , r e d e s c e n d e n s u ite so u s la c a n a l is a t io n au p o in t de d é p a r t e t s e t e r m in e p a r une c ré p in e r e m p l ie de g r a v ie r s a f in d 'é v i t e r l e s b o u ch a g es p a r la t e r r e . L e r o ta m è tr e peu t ê t r e « b y -p a s s e d » e t un sy s tè m e de q u a tre vannes p e rm e t d 'o b te n i r le d éb it de fu ite voulu .

370 C. TELLEER et al.

NATURE OU TERRAIN DE RECOUVREMENT

GARE DE PISTONS RACLEURS----------v

TERRE DE SACLAY

20m

TERRE OE SACLAY

20m

BANDE DE POUKEN LAINE DE VERRE E T BRAI

T *ENDUIT GRAS

GARE OE PISTONS ✓RACLEURS

= | — . » ARRIVÉE

c t a o e r

ТУРЕ DE PROTECTION EXTERNE DU FEEOER

NOTA : SIMULATEUR DE FUITES I

Figure 5

Im plantation de la conduite expérim entale.

Figure 6

Sim ulateur de fuite.

L a f ig u r e 7 in d iq u e l e s p o s s ib i l i t é s d e c i r c u la t io n de,s f lu id e s . N o u s r e m a rq u e ro n s un c i rc u i t d 'h o m o g é n é isa tio n du gaz contenu dans une capac ité in te r m é d ia i r e d e 5 m3, un e c a n a l is a t io n d e r e to u r du g a z r a d io a c t i f p e r m e t ta n t d e f a i r e c i r c u l e r en c i r c u i t f e r m é le g a z m a r q u é s a n s a v o i r à le r e j e t e r d a n s 1' a tm o s p h è re . U ne p o m p e d e 5 m 3/h p e r m e t l a c i r c u la t io n du g a z .

U ne cuve de 5 m3 s e r t à f a i r e l e s m é la n g e s h o m o g è n es liq u id e s , avec b r a s s a g e à a i r c o m p r im é . U ne p o m p e à e a u p e r m e t d ' i n j e c t e r l e l iq u id e m a r q u é d a n s l e p ip e - l in e .


CAPACITÉ INTERMEDIAIRE

Figure 7

Plan de circu lation des fluides:C ircu it d 'hom ogénéisation du gaz contenu dans la capac ité interm édiaire.

—♦ C ircu it d 'in jec tion du gaz de la cap a c ité in term édiaire dans la canalisation. C ircuit ferm é de c ircu lation du gaz pendant les essais.C ircuit d 'apport du gaz radioactif pour com pensation des fuites.

B . R e p é r a g e d e s fu i te s d 1 ea u

N o u s a v o n s e m p lo y é l a m é th o d e , d é jà co n n u e , c o n s is ta n t à m a r q u e r l ' e a u c o n ten u e d a n s l a co n d u ite , à l a l a i s s e r f u i r u n c e r t a in te m p s , p u is à r e m p la c e r c e tte eau ra d io a c tiv e p a r une eau non ra d io a c tiv e , en fin à f a i r e c i r c u le r un p is to n - r a c le u r d é te c te u r r e p é r a n t à t r a v e r s la p a r o i de l a co n d u ite l a r a d io a c t iv i té re te n u e d an s le s o l e n to u ra n t c e tte d e r n iè r e .


1. Expériences antérieures

Un c e r ta in -n o m b re d 'e s s a i s de d é te c tio n de fu ite s de liq u id e p a r r a d io é lé m e n ts ont é té r é a l i s é s s u r des t ro n ç o n s de condu ite a t te ig n a n t 5 km , p a r PUTMAN e t JE F FE R S O N 14 j en u ti l is a n t du sod ium -24 sous fo rm e deCOsHNai en so lu tio n dans 1' eau . P lu s ie u r s m é th o d es de d é te c tio n é ta ie n t p ra tiq u é e s :

a) in je c t io n d 'u n e fa ib le q u a n tité d 'e a u f o r te m e n t m a rq u é e d a n s l 'e a u p u re r e m p l is s a n t la condu ite e t m e s u re de la v i te s s e d 'é c o u le m e n t de l 'e a u due à la fu ite , av ec o b se rv a tio n de la chu te de v i te s s e a p r è s p a s s a g e d 'u n e fu ite ;

b) r e m p l is s a g e to ta l de la co n d u ite d 'e a u m a rq u é e de faç o n hom ogène, m is e en p r e s s io n s ta t iq u e p o u r p ro v o q u e r l a fu ite , p u is d é te c tio n de 1' e x t é r i e u r p a r t r o u s de so n d a g e où é ta ie n t in tro d u its d e s d é te c te u r s ;

c) t r a n s p o r t so u s p r e s s io n d 'u n e co lo n n e d 'e a u m a rq u é e p o u s s é e p a r de l 'e a u p u re ; à 1 k m d e r r i è r e l a so lu tio n r a d io a c t iv e , u n d é te c te u r av e c e n r e g i s t r e u r à f i l m a g n é tiq u e é t a i t in tr o d u it d a n s l e p ip e - l in e , r e m o r q u é p a r un p is to n é ta n c h e . Une s é r i e de s o u rc e s de co b a lt ja lo n n a it e x t é r ie u r e m e n t l a c o n d u ite . Au b o u t du p ip e - l in e , on s o r ta i t le d é te c te u r et. 1' e n r e g i s t r e u r , e t le f i l é t a i t d é r o u lé d an s un le c te u r e n r e g i s t r e u r , f o u rn is s a n t un g rap h iq u e . On pou v ait a in s i d é te c te r à t r a v e r s la p a ro i du tuyau le liqu ide r a d io a c t i f qu i s ' é t a i t é p a n c h é d a n s le s o l au v o is in a g e d e s p o in ts d e fu ite e t c e la s u r d e s tro n ç o n s de 20 km , p a r r e p é ra g e de s ig n a u x a n o rm a u x p a r r a p p o r t au x « to p s » p r é v u s , c r é é s p a r d e s s o u r c e s c o n n u e s de co b a lt-6 0 . L a d is ta n c e d é te c ta b le m a x im a le d é p e n d a it de 1' e n r e g i s t r e u r à f i l .

2. Choix du traceur lors de nos expériences

L e ra d io é lé m e n t d o it p o u v o ir ê t r e fa b r iq u é f a c i le m e n t d a n s u n e p ile , s a p é r io d e d o it ê t r e de l 'o r d r e de la jo u rn é e e t son ra y o n n e m e n t s u f f is a m m e n t d u r . D ' a u t re p a r t , le p ro d u it de b a s e do it ê t r e so lid e ou m ie u x en s o lu tio n e t le ra d io é lé m e n t do it ê t r e in tro d u it d an s une co m b in aiso n a s s e z r é a c tiv e p o u r q u 'u n e f ra c tio n -a p p ré c ia b le du t r a c e u r d e m e u re fix ée aux a le n to u r s de la fu ite e t p u is s e ê t r e d é c e lé e . Sont u t i l is a b le s : , 1' a r s e n i c - 76, le b r o m e - 8 2 , le t u n g s t è n e - 187 e* le s o d iu m -2 4 . E n f a i t , c ' e s t à c e d e r n ie r que l 'o n f a i t t ap p e l ( I l é m e t d e s ra y o n n e m e n ts y de 1,4 e t 2,8 M eV, on l ’ o b tie n t f a c ile m e n t e t s a p é r io d e d e 15 h p e r m e t l a v id an g e de l a co n d u ite a p r è s e s s a i ) .

3. Appareillage de détection et forme du diagramme obtenu

L ' a p p a re illa g e é le c tro n iq u e e s t c o n s titu é de q u a tre c o m p te u rs G e ig e r- M ü lle r qui re ç o iv e n t l e s r a d ia t io n s (fig. 8). L e s im p u ls io n s son t a m p lif ié e s e t 1' e n re g is tr e m e n t e s t r é a l i s é s u r un m agnétophone M inifon à f i l (la d u rée m a x im a le de d é ro u le m e n t, d 'a b o r d d 'u n e h e u re , a é té p o r té e à c inq h e u re s , e l le p o u r r a i t m ê m e ê t r e p o r té e à v in g t h e u r e s , s i l a g ra n d e lp n g u ë u r d e s c o n d u ite s l ' im p o s a i t ) . C e tte é le c tro n iq u e , a s s e z f r a g i le , e s t e n fe rm é e e t su sp e n d u e d a n s un c h â s s i s m é ta l l iq u e é ta n c h e que l 'o n in t r o d u i t d a n s u n p is to n - ra c le u r a tta c h é p a r un câb le m é ta lliq u e de 1,50 m , à un a u tre p is to n - r a c le u r jouan t le rô le de t r a c te u r .


SCHÉMA DU CIRCUIT ELECTRONIQUE DE DÉTECTION

Figure 8

A ppareillage de détection.

A p rè s e n re g is tre m e n t, on peu t so it e x p lo ite r rap id e m en t le s r e n s e ig n e m e n ts r e c u e i l l i s en « é c o u ta n t» l a b an d e (n o m b re de p ic s ) , so it l e s ' t r a n s c r i r e so u s fo rm e de d ia g ra m m e d 'e n r e g i s t r e m e n t s u r p a p ie r ( in te n s ité du s ig n a l en fo n c tio n de l a d is ta n c e ) .

Nous donnons, c i- jo in t (fig. 9) un exem ple de g raph ique obtenu. Il s 'a g i t d 'u n e s s a i e ffec tu é le 15. 11. 1961. L a s o r t ie é ta i t d 'e n v ir o n 70 д c p a r fu ite ; s e u le l a fu ite d a n s 1' a r g i l e a v a it é té o u v e r te , b ie n e n c a d r é e p a r le s t r o i s iè m e e t q u a tr iè m e s o u r c e s de c o b a l t - 60 de 2 2 цс. On la s i tu e s u r le g r a ph ique (d is ta n c e s én a b s c is s e s , h a u te u r du s ig n a l en o rd o n n ée s) à 83 m de m u r d e b é to n de l a g a r e de d é p a r t . E l le e s t en r é a l i t é à 81 ,30 m : l a p r é c is io n e s t donc de l 'o r d r e de ± 2 m , ce qui e s t s a t is f a i s a n t dans la p ra tiq u e in d u s t r ie l le . On peu t o b s e rv e r que, p o u r une m ê m e a c tiv ité d es s o u rc e s de c o b a lt-6 0 (22 /lîc) , on o b tie n t d e s p ic s de h a u te u rs d if fé re n te s . C eci e s t p r o b a b le m e n t dû à d es d if fé re n c e s dans la v i te s s e de p a s sa g e du p is to n - r a c le u r d é te c te u r en fa c e de c e s d if fé re n te s so u rc e s . Donc la h au teu r du s ig n a l n 'e s t p a s ab so lu m en t r e p r é s e n ta t iv e de l 'a c t iv i t é qui l ' a provoquée, m a is en fo u rn it to u t de m ê m e un o r d r e d e g ra n d e u r . O n a d 'a u t r e p a r t r e m a r q u é , ' s u r to u s l e s d ia g ra m m e s o b ten u s , que l 'a s p e c t d è s fu ite s e s t d if fé re n t de ce lu i d e s s o u rc e s p o n c tu e lle s (dont le s ig n a l e s t b ien m o in s « é ta lé » ) .


Figure 9

Exemple d 'enregistrem ent de fuite.

4. Résultats expérimentaux

L 1 in s ta l la t io n d é c r i te p lu s h au t nous a p e r m is de c r é e r p a r le s s im u la te u r s , d e s fu ite s a r t i f ic ie l le s de liq u id e m a rq u é , s o it in je c té d ire c te m e n t dans la b ran c h e du s im u la te u r a l lan t v e r s la c ré p in e , so it contenu sous p r e s s io n dans la c a n a lisa t io n a p rè s m a rq u a g e to ta l de l 'e a u de la condu ite . Nous avons é tu d ié l 'in f lu e n c e de d if fé re n ts fa c te u rs :

a) In fluence de la fo rm e ch im iq u e so u s la q u e lle le t r a c e u r e s t in tro d u it: no u s av o n s c o m p a ré la f a c i l i té de d é te c tio n de l 'e a u m a rq u é e p a r du c h lo r u r e de so d iu m , du b r o m u r e de so d iu m , du b ic a rb o n a te de so d iu m , d an s le s q u e ls le sod ium é ta i t ra d io a c tif ; à a c tiv ité ég a le , le s r é s u l t a ts s.ont id en tiq u e s . Le sod ium r e s te p ro ch e de la fu ite , c a r le t e r r a in joue le r 6 1 e d 'é c h a n g e u r d 'io n s (e x c ep tio n f a ite p o u r le sa b le ) e t le f ix e . Q uand on m a rq u e le b ro m u re de so d iu m à la fo is s u r le b ro m e e t le sod ium , on ne f a v o r is e p as l a d é te c tio n . E n e f fe t , l o r s d 'u n e d é te c tio n t r è s r a p id e a p r è s in je c t io n , on o b tie n t d e s r é s u l t a t s p ro c h e s d e s p ré c é d e n ts , m a is s i la d é te c tio n ta rd e un peu , le b ro m e e s t d ra in é le long de la condu ite s a n s s e f ix e r s u r le t e r r a in . I l en r é s u l t e q u ' à a c t iv i té é g a le , le p ic r e p r é s e n ta n t l a fu ite a t e n d an c e à s ' é t a l e r j c e qu i d im in u e la p r é c is io n .

b) In flu e n ce d e l 'a c t i v i t é to ta le du liq u id e é c o u lé e t s é c u r i té : la fu ite é ta n t m a in ten u e lo r s de chaque e x p é r ie n c e à d éb it de 50 l / h pendant 1 h eu re , nous avons m a rq u é le s 7000 1 d 'e a u con tenus dans le fe e d e r su c c e ss iv e m e n t av ec 200 m e de so d iu m -2 4 , p u is av ec 150, 100, 50, 20 e t en fin 10 m e. L es g rap h iq u es son t to u s du m êm e type e t l 'o n co n s ta te que l 'o n d istingue encore t r è s b ie n u n e fu ite de 50 1 d 'e a u s ' i l y a une a c t iv i té de 10 m e p o u r 7000 1 d 'e a u . I l e s t donc in u ti le d 'u t i l i s e r d e s a c t iv i té s im p o r ta n te s .

E n s u ite , en t r a ç a n t à 10 m e p o u r l e s 7000 1 du p ip e - l in e , n o u s av o n s u t i l is é d iv e rs tau x de fu ite : 50 l /h , 25 l /h , 12 l /h , pu is 7 l /h . A 7 l /h , pen-


dan t 1 h e u re , la l im ite de d é tec tio n se tro u v e a tte in te . On peu t e s t im e r a in s i que p o u r d é te c te r c o n v e n a b le m e n t un e fu ite liq u id e , i l fa u t q u ' un e a c tiv i té d e 20 цс s o r te en r e la t iv e m e n t p eu de te m p s p a r l a fu ite ; c e la c o r re s p o n d d 'a i l l e u r s à l 'o r d r e de g ra n d e u r de l 'a c t i v i t é d e s s o u rc e s de c o b a lt-6 0 qui ja lo n n en t la con d u ite .

C e r é s u l t a t é t a i t p r é v is ib le s a n s ê t r e év id en t, c a r un e fu ite n ' e s t p a s u n e s o u r c e p o n c tu e lle e t so n é ta le m e n t p e u t a v o i r u n e in f lu e n c e s e n s ib le .

R a p p e lo n s que l e s c o n c e n t r a t io n s m a x im a le s a u t o r i s é e s au p r e m i e r p o in t d e b o is s o n so n t de 0,2 m c /m 3 p o u r l e so d iu m -2 4 e t 0 ,3 m e /m 3 p o u r l e b r o m e - 8 2 .

U ne a c t iv i té d e 20 ;uc p o u r 7 .1 c o r r e s p o n d à 2, 8 m e p a r m3 d 'e a u , s o it 14 fo is la CMA. Il fa u t donc d i lu e r 14 fo is av an t de r e j e t e r 1' eau m a r quée (é tang , c o u r s d 'e a u ) ou l a i s s e r d é c r o î t r e deux jo u r s e t d em i.

c) In flu e n ce du t e r r a i n : d e s f u ite s de m ê m e a c t iv i té ont é té r é a l i s é e s d a n s l e s q u a t r e t e r r a i n s d i f f é r e n ts . P o u r l a c r a i e , la t e r r e d e S a c la y e t l 'a r g i l e , le s signaux ob tenus ont eu se n s ib le m e n t la m êm e a l lu r e .P a r co n tre , p o u r l e s a b le , le s ig n a l a é té b e a u c o u p p lu s é ta lé e t c e t é t a le m e n t s ' e s t a c c r u a v e c le te m p s . C e p h én o m èn e t r a d u i t le m an q u e d 'a p t i tu d e du sa b le à f ix e r le so d iu m , ce qui n ' e s t p a s le c a s d e s a u t r e s t e r r a i n s .

d) In flu e n ce d 'u n e d ilu tio n à l 'e n d r o i t de la fu ite , c 'e s t - à - d i r e , d 'u n le s s iv a g e du so l a c tiv é p a r de 1' eau p u re : nous avons in je c té , en le s p o u s s a n t p a r C 0 2 d i r e c te m e n t d a n s le tu b e d e s c e n d a n t du s im u la te u r , 250 ¡лс de so d iu m -2 4 d ilu é s dans 4 cm 3 d 'e a u ; nous avons n e tto y é en su ite p a r 6 cm3 d 'e a u . P u is n o u s a v o n s e f fe c tu é un p a s s a g e du p i s t o n - r a c l e u r d é te c te u r .

D ans un e d eu x ièm e o p é ra tio n , nous avons p a r l a m ê m e v o ie f a i t p a s s e r 100 1 d 'e a u p u re , donc obtenu une d ilu tion th é o riq u e de 10 000. Le g raph ique ob ten u d a n s c e s c o n d i t ip n s m o n tr e d e s p ic s r é d u i t s d e m o it ié e n v iro n p a r r a p p o r t à ce u x du g ra p h iq u e p ré c é d e n t .

N ous en d é d u iro n s qu ' on p eu t la rg e m e n t la v e r la condu ite à 1' eau p u re s a n s a l t é r e r beau co u p la n e t te té d es p ic s du g rap h iq u e .

P o u r g é n é r a l i s e r , i l a u r a i t é té b o n d ' i n j e c t e r 1 000 ou 2 000 1, m a is c e c i a u r a i t a b îm é le t e r r a i n e t c r e u s é line c a v ité im p o r ta n te a u to u r d e l a c r é p in e du s im u la te u r .

e) In flu e n ce du n o m b re de r e s s u y a g e s ; le r e s s u y a g e c o n s is te à p a s s e r un p is to n - r a c le u r d an s la condu ite , p o u ssé p a r de l 'e a u p u re , a fin de r e m p la c e r 1' eau m a rq u é e p a r c e tte d e r n iè re , s a n s a u tre m é lan g e que c e lu i qui e s t c a u sé p a r le s fu ite s du p is to n .

N ous a v o n s c o n s ta té q u 'u n s e u l r e s s u y a g e s u f f i s a i t p o u r é l im in e r la r a d io a c t iv i té à l ' i n t é r i e u r de l a co n d u ite . C e c i e s t a p p a ru s u r le gaph ique p a r un b r u i t de fond d e m e u ré c o n s ta n t e n t re le p r e m ie r e t le d eu x ièm e r e s su y ag e , ce qui p ro u v e l 'é t a n c h é i t é du p is to n .

D ans lé c a s d 'u n e lo n g u e u r im p o r ta n te de co n d u ite à v é r i f i e r , le m a r quage to ta l de 1' eau n ' e s t p a s p o ss ib le e t l ' on fa i t p r o g re s s e r sous p re s s io n d an s la c a n a lis a tio n une co lonne d 'e a u m a rq u é e dont le p a s sa g e devan t c h a que fu ite c o n d u ira à é m e t t r e v e r s 1' e x té r ie u r u n e q u a n tité de p ro d u it m a r q u é d e 20 à 25 juc. L e g ra p h iq u e o b te n u a é té s e m b la b le au x p r é c é d e n t s .

f) In flu e n c e d e l a v i t e s s e du p is to n d é te c te u r : l e p a s s a g e du p is to n - r a c le u r d é te c te u r a é té e ffec tu é au c o u rs d es e s s a is à une v i te s s e c o m p rise e n t r e 200 e t 900 m / h s a n s m o d if ic a tio n a p p r é c ia b le s u r l ' a l l u r e d e s g ra p h iq u e s .


C onclusion : C es e s s a is m o n tre n t q u 1 av ec l 1 a p p a re il la g e u t i l i s é on d é te c te t r è s fa c ile m e n t une fu ite liq u id e à condition qu1 i l s o r te p a r c e l le - c i 20 à 25 juc de p ro d u it r a d io a c t i f , 1 ' é v a c u a tio n du l iq u id e m a rq u é a p r è s u s a g e s e f a is a n t p a r d ilu tio n , s to c k a g e ou c o m b in a iso n d e c e s d eu x m o y e n s .

C . F u i te s de gaz

L a m é th o d e c h o is ie c o n s is ta i t é g a le m e n t à d é te c te r un e c o n ta m in a tio n du t e r r a i n ; no u s av o n s e x a m in é l e s p o s s ib i l i té s :

a) d 'u t i l i s e r un m a rq u a g e hom ogène du gaz (a c tiv ité sp é c if iq u e en t r a c e u r co n s tan te to u t le long de la ca n a lisa tio n , ne d éb itan t que p a r le s fu ite s);

b) d 'u t i l i s e r l e m a rq u a g e , p a r in t r o d u c t io n 'd u t r a c e u r en u n e s e u le f o is , p ro d u is a n t u n e v a g u e m a rq u é e p o u s s é e p a r u n g a z in a c t i f .

I l co n v ien t de r e m a r q u e r que l a d é te c tio n in te r n e , c o n fo rm e à l a m é th o d e e x p o s é e en p h a s e liq u id e , donne é g a le m e n t en g a z d 'e x c e l l e n t s r é s u l ta ts , m a is n e p eu t c o n v e n ir aux a r t è r e s de d is tr ib u t io n de gaz en r a is o n de l a p r é s e n c e de jo in ts qui in te r d is e n t le p a s s a g e de p is to n s - r a c le u r s . IL s 'e n s u i t que nous so m m e s o b lig é s d 'u t i l i s e r une d é te c tio n p a r l 'e x t é r i e u r , f a c i l i t é e p a r l 'e m p l o i d 'u n é m e t te u r g a m m a é n e rg iq u e . C 'e s t p o u r c e la que p o u r l ' i n s t a n t n o u s av o n s l im i té n o s e s s a i s à l 'e m p lo i de b r o m u re de m é th y le m a rq u é au b ro m e - 82, su iv a n t la m éth o d e p ro p o sé e p o u r le s c â b le s té lép h o n iq u es p a r PA G ES e t LEVËQ U E [5].

S u r la co n d u ite d é c r i te p ré c é d e m m e n t l e s e x p é r ie n c e s s y s té m a tiq u e s s o n t e n c o r e en c o u r s e t l e s r é s u l t a t s p r é s e n t é s i c i n e so n t que p a r t i e l s . ,

1. Considérations théoriques

L e s c o n s id é ra tio n s th é o r iq u e s qui su iv e n t so n t ég a le m en t v a la b le s p o u r le s d é te c tio n s de fu ite s de liq u id e , m a is e l le s r e v ê te n t une im p o r ta n c e p a r t ic u l iè r e p o u r le s fu ite s s u r un c i r c u i t d 'a l im e n ta t io n en gaz où, le gaz d e v an t ê t r e coupé chex le s ab o n n és, le te m p s m is à la d isp o s itio n de 1' équ ipe d e r e c h e r c h e s e s t c o u r t e t n e s a u r a i t d é p a s s e r q u e lq u e s h e u r e s .

a) M a rq u a g e h o m o g è n e ; t e m p s o p tim u m p o u r l a d é te c tio n : S o it t l e te m p s é c o u lé à p a r t i r du m o m e n t où le liq u id e r a d io a c t i f a é té m is «n c o n t a c t a v e c le t e r r a i n p a r 1' in te r m é d ia i r e de l a fu ite . P o u r t = 0, 1' a c t iv i té s u r le t e r r a i n e s t n u lle ; p o u r t = °o, 1' a c t iv i té s u r le t e r r a i n e s t é g a le m e n t n u lle , i le r a d io é lé m e n t ay a n t c o m p lè te m e n t d é c rû . I l s 'e n s u i t q u ' i l e x i s te ü n te m p s topt où 1' a c t iv i té du t e r r a i n e s t m a x im u m .

L 'a c c r o i s s e m e n t d 'a c t i v i t é dA e n t r e l e s te m p s t e t t + d t e s t dû:« à l 'a p p o r t de l a fu ite : dA1 =qa0e-^t d t._ à l a d im in u tio n d e l 'a c t i v i t é A p a r d é c r o is s a n c e : . dA 2= -X A (t)d t.

C e tte é q u a tio n a p o u r so lu tio n :

A (t) = qaot e_Xl

e t A(t) p a s s e p a r un m a x im u m p o u r t= l/X = T j/0 ,7 (so it 21 h p o u r le 24Na e t50 h p o u r le 82Br).

D ans c e tte e x p r e s s io na 0 = a c t iv i té sp é c if iq u e au te m p s t = 0,A. = c o n s ta n te ra d io a c t iv e du t r a c e u r ,


A (t) = a c t iv i té s u r le t è r r a i n au te m p s t , q = d é b it de fu ite .

L a c o u rb e A (t) en fo n c tio n d e (t) e s t r e p r é s e n té e s u r l a f ig u re 10. On r e m a r q u e que c e t te c o u rb e p r é s e n te u n m a x im u m p la t (94% du m a x im u m

10,96

0,88

0,76

0,66

Courbe de l 'a c tiv ité fixée en fonction du temps (m élange in itia l hom ogène).

f ix é en u n e p é r io d e ) e t que m ê m e en l a i s s a n t f u i r le l iq u id e p e n d a n t une. d e m i p é r io d e , l ’ a c t iv i té e s t d é jà l e s 2 /3 de l 'a c t i v i t é m a x im u m p o s s ib le .

P a r co n séq u en t, 1' in té r ê t de l a i s s e r fu ir l a fu ite pendan t un te m p s s u p é r ie u r à un e d e m i p é r io d e d im in u e e t i l e s t to ta le m e n t i l l u s o i r e p o u r u n

b) M a rq u a g e p a r un e v ag u e de t r a c e u r , lo n g u e u r m ax im u m e x p lo ra b le : I l e s t é v id e n t que l ' i n j e c t i o n d 'u n e v ag u e de t r a c e u r d 'a c t i v i t é in i t ia le t o t a le A^ n e p e r m e t p a s d 'e x p l o r e r u n e lo n g u e u r in f in ie d e c a n a l is a t io n .

P o u r p e r m e t t r e la d é te c tio n d 'u n e fu ite de d éb it q, p e t ite d evan t le d é b it Q de l a c a n a l is a t io n ,le m ode de d é te c tio n (e n se m b le d e s c o n d itio n s g éo m é tr iq u e s e t du d é te c te u r) n é c e s s i te la p ré s e n c e s u r le t e r r a in , au te m p s t où s 'e f f e c t u e l a m e s u r e , d 'u n e a c t iv i té m in im u m « a m» t e l l e que l 'o n a i t

C e tte r e la t io n d é f in it le te m p s в au bo u t duquel la d é te c tio n n ' e s t p lu s p o s s ib le

A ( t) A(max)

02

3TT PÉRIODE

Br18 h 36 h 50 h 72 h 108 h

Figure 10

te m p s s u p é r ie u r à u n e p é r io d e .

a(t) = A (t) 3 =, Aoe-xt ^ > a m.

M a is au te m p s в la vague a p a rc o u ru une lo n g u e u r L = Q 0 /S (S = se c tio n d e l a c o n a lis a t io n ) e t l a lo n g u e u r m a x im u m e x p lo ra b le e s t a l o r s


t Q t g An bmax-sx L°gQani.R e m a rq u o n s que l e s deux c a lc u ls p r é c é d e n ts su p p o se n t que l 'a c t i v i t é

s u r l e t e r r a i n e s t f ix é e a u l ie u d e fu i te . D an s l a r é a l i t é , l 'u t i l i s a t i o n de b r o m u re de m é th y le m o n tre q u ' i l y a d iffu s io n d 'u n e p a r t i e du gaz v e r s le so l , ce qu i d im in u e le s q u a n tité s de r a d io é lé m e n t à u t i l i s e r e t f a c i l i te une d é te c tio n r a p id e .

E nfin , en p ra tiq u e , d an s le c a s du m a rq u a g e d 'u n e v ague , i l e s t g én é ra le m e n t p o s s ib le d 'a g i r s u r le d éb it Q de la c a n a l is a t io n e t de le d im in u e r to u t en m a in te n a n t la p r e s s io n c o n s ta n te p o u r l a i s s e r q c o n s ta n t . C e p r o céd é augm en te a(t), donc l a i s s e p a s s e r p a r l a fu ite une q u an tité p lu s g rande , ce qui en c o n tre p a r t i e d im in u e la lo n g u e u r m a x im u m e x p lo ra b le av e c une a c t iv i té in je c té e d onnée .

I l s 'e n s u i t q u e ,s u r u n c a s c o n c r e t , l e ch o ix d e l a m é th o d e d é p e n d ra e s s e n t ie l le m e n t :

a) du te m p s m is à la d is p o s i t io n d e l 1 é q u ip e d e r e c h e r c h e s ;b) d e Q e t d e l a fa ç o n do n t o n p o u r r a l e m o d if ie r ;c) d e l a lo n g u e u r d e l a c a n a l is a t io n .

2. Préparation du traceur

I l a p a ru o p p o rtu n d e p r é p a r e r le t r a c e u r g az eu x s u r l e l ie u m ê m e de l 1 e x p é r ie n c e , à p a r t i r du 82BrNH4. E n e f f e t , u n e t e l l e p r é p a r a t i o n é v i te l e s m a n ip u la tio n s en la b o ra to i r e e t p a r là m ê m e , d im in u e le d é la i e x is ta n t e n t r e s o r t ie de r é a c te u r e t débu t de l 'e x p é r i e n c e .

I l e s t é g a le m e n t a p p a ru que le ВгЗМЩ p o u v a it ê t r e i r r a d i é en so lu tio n d a n s u n e a m p o u le de q u a r tz . E n e ffe t, l ' i o n B r" a g it a lo r s c o m m e in t e r - c e p te u r de ra d ic a u x l ib r e s , a ttén u e fo r te m e n t l e s e ffe ts de ra d io ly s e , év ite donc le d égagem en t d ' 0 2 , ce qui conduit en fin d 'i r r a d ia t io n à des p re s s io n s a c c e p ta b le s d an s l 'a m p o u le de q u a r tz .

A la s o r t ie de r é a c te u r , le c o n ta in e r i r r a d i é e s t t r a n s p o r té s a n s d é la i s u r le t e r r a i n d an s un c h â te a u de "plomb s p é c ia le m e n t conçu p o u r la tr a n s '- fo rm a tio n du BrNILj en ВгС Н з (fig . 11). A p rè s b r i s de 1' am pou le de q u a r tz , l e r é a c t i f (8 0 4 (СН з)г+ 1 / 6 en v o lu m e d e SQ^H^) e s t in tro d u it en e x c è s s u r l a s o lu t io n d e B rN H 4 .(la r é a c t io n to ta le s e m b le n ' a v o i r l ie u qu e p o u r un e x c è s de 5 à 6 fo is l e s p ro p o rtio n s s to e c h io m é tr iq u e s) e t la r é s is ta n c e p e r m e t un chauffage à 80°C. L e b ro m u re de m é th y le a c tif dégagé a lo r s e n tra în é p a r du b ro m u re de m é th y le in a c tif p ro v en an t d 'u n e x tin c te u r .

D ans le c a s de la m éthode p a r vague, od la is s e d ire c te m e n t le gaz p ro d u it s 'é c o u l e r d a n s l a co n d u ite ; d a n s le c a s d e m é la n g e h o m o g è n e , i l e s t p o s s ib le de p ié g e r l e g az (c a rb o g la c e ) e t d e le r e l â c h e r au m o m e n t vou lu a v e c u n e p o m p e d o s e u s e .

3. Résultats

L e s d é te c t io n s d e s f u i te s e f f e c tu é e s à 1' a id e d e d é t e c te u r s p o r ta t i f s à s c in t i l la t io n o n t m o n t r é que:D an s l e c a s d 'u n m é la n g e h o m o g èn e :

APPLICATIONS DES RADIOELEMENTS A PÉRIODE COURTE 379

Figure 11

C ontainer de préparation du® BrCH3 sur le terrain.

a) П s u f f is a it g é n é ra le m e n t q u 1 e n v iro n 2 m e de t r a c e u r so ie n t p a s s é s p a r la fu ite p o u r r e n d re c e l le -c i d é tec tab le . R appelons que la fu ite s e tro u v e s o u s l a c a n a l is a t io n , s o i t à e n v iro n 1 ,30 m du s o l , c e q u i p ro u v e que la d if fu s io n du b r o m u r e d e m é th y le v e r s l e s o l e s t r é e l l e e t in te n s e .

b) L e d é te c te u r â s c in ti l la t io n d é c è le une a c tiv i té m ax im u m s u r le t e r r a in 17 h e n v iro n a p r è s l 'o u v e r t u r e d e s fu ite s , ce qui c o r r o b o r e l e s c o n c lu s io n s p r é c é d e n te s .

c) Le te m p s n é c e s s a i r e à la d é tec tio n dépend fo rte m e n t du déb it de fu ite . D ans le c a s de p a s sa g e d 'u n e vague:

a) L e s p lu s p e t i te s f u i te s que n o u s a y o n s pu d é c e le r c o r r e s p o n d a ie n t à d e s d é b i ts de f u i te s de 15 l / h e n v iro n . C e s f u i te s f u re n t d é c e lé e s a p r è s le p a s s a g e d 'u n e v ag u e d 'a c t i v i t é to ta le in i t ia le de 250 m e en 82Br, s u r la c a n a lisa tio n d éb itan t à 3,5 m 3/h (so it env iron 1 m e to ta l p a s s é p a r le s fu ites). P o u r c e s fu ite s , l 'u n e , d an s la c r a ie , p ré s e n ta i t une a c tiv ité m axim um 26 h a p rè s le début de l 'in je c t io n , a c tiv ité qui co rre sp o n d a it à"un signal d e 800cps p o u r un b r u i t d e fond de 100 c p s . L ' a u t re , d an s 1' a r g i le , p r é s e n ta i t 1' a c

380 C. TELLŒR et aL

t iv i té m a x im u m 24 h a p r è s le d éb u t d e l ' in je c t i o n , e t d o n n a it un s ig n a l de 400 c p s p o u r le m ê m e b r u i t d e fond.

b) L e b r o m u re d e m é th y le é t a i t en b o u t d e c a n a l is a t io n p ié g é s u r du c h a rb o n a c tif . L e p iè g e a g e fu t e x c e lle n t, m a is on s 'a p e r ç u t que le ch a rb o n d é g a z a it e t u n e g ra n d e p a r t i e d e 1' a c t iv i té fu t en d é f in i tiv e r e lâ c h é e d an s l 'a tm o s p h è r e . C ependan t, co m m e ce re lâ c h a g e e s t le n t, l e s co n d itio n s de s é c u r i té so n t s u f f is a n te s .

C onclusion: L e s r é s u l ta ts p ré c é d e n ts so n t p a r t ie ls , m a is en c o u rag ea n ts . En e ffe t, i l s ' a v è re que de fa ib le s a c tiv i té s de 1* o r d re de qu elq u es m e p a s s a n t p a r la fu ite so n t s u f f i s a n te s p o u r d é t e c te r d e s fu i te s d e l 'e x t é r i e u r en to u t t e r r a i n .

L e te m p s p en d a n t le q u e l le g a z e s t co u p é c h e z l e s ab o n n é s e s t l im i té au te m p s de p a s sa g e de la vague e t p a r su ite su ffisam m en t co u rt p o u r re n d re la m éthode exp lo itab le .

CONCLUSION GÉNÉRALE

L e c o n trô le d e s SQUdures p a r g a m m a g ra p h ie é ta n t m is à p a r t , l ' i n d u s tr ie g a z iè re f r a n ç a is e a donc la rg e m e n t u t i l i s é le s r a d io é lé m e n ts à p é r io d e c o u r te .

C e r ta in e s de c e s a p p lic a tio n s so n t s u s c e p tib le s d 'im p o r ta n ts d év e lo p p em e n ts p ra tiq u e s , en p a r t i c u l ie r l a r e c h e r c h e d es fu ite s de gaz s u r le s c a n a l is a t io n s de d is tr ib u tio n .


El] CADŒRGUES. R. e t LEVÊQUE. P . . Rev. chaleur e t industrie 318 (1951).[2] FISHER, C . e t LEVÉQUE, P . , Annales de l ' Institut technique des bâtim ents e t travaux publics 59 (1952)

1187.[S] BRION, J . . COURTOIS. G. e t PRADEL, J . . Résultats non publiés.[4] PUTMAN, J. L. e t JEFFERSON, S . , Actes Conf. in t. u til. EAFP (ONU) 15(1955) 173.[5] GUÉRON, J. e t PAGES, A ., Rev. c ib le s e t transmissions 1(1952) 96.

D I S C U S S I O N

C . T E L L IE R : I sh o u ld l ik e to m a k e a few g e n e r a l r e m a r k s on th i sp ro b le m o f r a d io is o to p e t r a c e r s . In th e c a s e o f r a d io is o to p e fo g g in g -o i l an d a i r - r e n e w a l t e s t s , w h ich c a n now b e r e g a r d e d a s fu lly - f le d g e d t e c h n iq u e s , th e te n d e n c y in in d u s t ry i s to u s e th e new m e th o d s s p o r a d ic a l ly fo r a w h ile and th e n to d ro p th e m a l to g e th e r . N o n - r a d io a c t iv e m e th o d s a r e p r e f e r r e d — ev en a t th e c o s t of r e l ia b i l i ty — s im p ly b e c a u se th e y do no t g ive r i s e to any new p ro b le m s .

O nce a c l e a r e c o n o m ic a d v a n ta g e i s a p p a re n t , h o w e v e r , a c h a n g e in a t t i tu d e b e c o m e s n o t ic e a b le . A good e x a m p le i s p ro v id e d by o u r le a k a g e t e s t s . T h e u s u a l h y d r a u l ic le a k t ig h tn e s s t e s t r e l i e s on v is u a l d e te c t io n . In th e ev e n t o f r a i n th e m e th o d b r e a k s dow n, and th e c o s t o f th e f a i lu r e is l i a b le to be h ig h . T h e o bv ious a l te r n a t iv e i s to u s e s o d iu m - 24.


W hen i t c o m e s to d e te c t in g g a s le a k s in a n u r b a n n e tw o rk t h e r e a r e n u m e ro u s co n v e n tio n a l m e th o d s ( e .g . in f r a - r e d r a y s ) , bu t w ith a l l o f th e m th e gas h as to m ake co n tac t w ith th e d e tec tio n a p p a ra tu s . In m any in s ta n c e s , h o w ev er, and e s p e c ia lly w h ere th e s o i l -c o v e r i s im p e rm e a b le , th e g as m ay t r a v e l s e v e r a l dozen m e te r s b e fo re re a c h in g th e a p p a ra tu s . T h is m ay m ean u n n e c e s s a r y e x c a v a tio n b e fo re th e le a k c a n b e lo c a te d . T h is c a n b e e x t r e m e ly ex p en siv e as w ell a s in conven ien t fo r th e c o n su m e r. R ad io iso to p es have an obvious ad v an tag e . O ur t e s t s have e s ta b lish e d th a t th e y only t r a v e l s h o r t d is t a n c e s . T h e m e th y l b ro m id e c o l le c ts in th e s o i l - c o v e r w ith in a m e te r o r so of th e le a k , and th e h a rd g am m a ra d ia tio n f ro m th e b ro m in e - 82 p e n e tra te s th e s o i l -c o v e r . It is p lanned to c a r r y out sh o r tly in d u s tr ia l te s ts on p ip e - le n g th s of s e v e r a l k i lo m e te rs . We w ill th e n b e ab le to cu t th e g as su p p ly a t 10 o 'c lo c k in th e even ing , c a r ry in g out dum m y te s t s im m e d ia te ly an d th e n c a r r y ou t th e a c tu a l d e te c tio n t e s t 2 h a f te r in je c t io n . A f te r th e g as c i rc u it h as b een te s te d s e v e ra l t im e s , i t should th en be p o ss ib le to c h a r t the ex a c t lo c a tio n of th e le a k s and r e - e s ta b l i s h th e g as supp ly a t 6 o 'c lo c k in th e m o rn in g . E ig h t h o u rs w ould th u s be av a ila b le fo r p a s s a g e of th e r a d io a c tiv e g a s to th e end of th e le n g th of p ip e u n d e r ex a m in a tio n w h ere i t w ould b e tra p p e d on a c tiv e c a rb o n o r d ry ic e and cou ld , if n e c e s s a r y , be r e - u s e d . F o r p sy c h o lo g ic a l r e a s o n s i t is no t d e s ira b le to c o n tam in a te th e n o rm a l gas supp ly to th e c o n s u m e r , even a t c o n c e n tra tio n s below th e m ax im u m p e r m is s ib le le v e ls (M PC).L e g a lly , o u r c o m m itm e n ts a t th e p r e s e n t t im e a r e co n fin ed to c o m p lia n c e w ith th e s e M PC v a lu e s and to r e p o r t in g a l l t e s t s to th e C o m m is s io n i n t e r m in i s t é r i e l l e d e s r a d io é lé m e n ts ( In te rd e p a r tm e n ta l C o m m itte e on R a d io e le m e n ts ) .

In th i s w ay i t w ill , I h o p e , b e p o s s ib le g r a d u a l ly to r e a c h th e s ta g e w h ere ra d io iso to p e m e th o d s beco m e g e n e ra lly accep ted fo r sa fe and r e l ia b le ro u tin e u se .

A . S E L L E R IO : A t P a le r m o w e h a v e a l s o b e e n d o in g s o m e w o rk onle a k d e te c tio n .

A nyone in te r e s te d in th e s e e x p e r im e n ts ca n find d e ta ils in th e p ro c e e d in g s o f th e P a le r m o A c c a d e m ia d i S c ie n z e L e t t e r e e A r t i , 23 Ju n e , 1962, "Д p ro b le m a d e lla r iv e la z io n e d i fughe in condotte s o t te r r a te di gas m edian te ra d io is o to p i . Im p ie g o d i a e r o s o l" , G . A gelao and Z . T e s a u r o D a rd a n o n i.

E . SOMER: I w onder w hether the au th o rs m ade any a ttem p t to exam ineth e c o r r o s iv e p r o p e r t i e s o f t h e i r m e th y l b ro m id e o r t r i e d to d e te r m in e w h e th e r o r not i t is e n t ire ly f re e f ro m , sa y , su lp h u r ic ac id . T h is would be a n im p o r ta n t c o n s id e r a t io n i f i t i s p la n n e d to u s e th i s m e th o d f o r th e d e te c tio n of le a k s in lo n g -d is ta n c e te le p h o n e c a b le s f i l le d w ith c o m p re s s e d a i r .I a s k th is b e c a u s e I b e l ie v e th a t m e th y l b ro m id e i s in fa c t u s e d in F r a n c e fo r le a k d e te c tio n in c a b le s .

G. COURTOIS (on b e h a lf of th e a u th o rs ) : We have no t m a d e any s y s te m a t ic c o r r o s io n s tu d ie s w ith th e m e th y l b ro m id e , n o r have we ex a m in e d i t f o r s u lp h u r ic a c id c o n te n t. W e h a v e , h o w e v e r , c a r r i e d o u t a n u m b e r of e x p e r im e n ts to s tu d y th e fix a tio n of m e th y l b ro m id e on v a r io u s su b s ta n c e s su c h a s p o ly th e n e , r u b b e r , s t e e l and c o p p e r , a s a r e s u l t o f w h ich we now av o id u s in g r u b b e r fo r jo in ts .


T h is tech n iq u e is no lo n g e r u se d fo r te lephone c a b le s in F ra n c e . T h e re a r e in an y c a s e .v e ry few c a s e s o f le a k s in te le p h o n e c a b le s n o w ad ay s; we h a v e had no q u e r ie s fo r th e p a s t f iv e o r s ix y e a r s , n o t, in fa c t , s in c e th e r e a s o n s f o r th e le a k s w h ich u s e d to o c c u r a t on e t im e w e r e d e te r m in e d .

R. CORNUET (C hairm an): T he m ethy l b ro m id e m ethod w as, o f c o u rse ,v e ry m uch u se d in 1952 and in subseq u en t y e a rs fo r le a k d e tec tio n in c a b le s . S ince th e n , a s M r. C o u r to is h a s p o in ted ou t, th e m a n u fa c tu r in g flaw in th e c a b le s h a s b e e n d is c o v e re d . T h e re i s , h o w ev e r, a n o th e r r e a s o n why th is te c h n iq u e i s no lo n g e r u s e d , and th a t i s th a t o th e r c o m p e ti tiv e te c h n iq u e s , su c h a s h a lo g en d e te c tio n , w h ich a r e ju s t a s s e n s it iv e y e t e a s ie r to h an d le h av e now b e c o m e a v a ila b le .

APPLICATIONS DU SODIUM-24 A DES MESURES DE DEBITS ET DE RECHERCHES DE FUITES

J. GUIZERIX E T R. C O R N U E T

CEN TRE D ’ ÉTU D ES NUCLEAIRES, GRENOBLE, FRAN CE


APPLICATION OF SODIUM-24 TO FLOW-RATE MEASUREMENTS AND LEAK DETECTION. The authors first give a description of some experim ents in which sodium -24 was em ployed to e lim inate decontam ination problems and to permit repetition of tracer injections. The sodium irradiation was carried out in the "Melusine” swimming-pool reactor at the Centre d 'études nucléaires in Grenoble.

To discover a leak in a central heating circuit the water circuit was tagged with Na24 - labelled sodium carbonate. A precise plan of the piping was m ade in order to delim it the sections for study after drainage and rinsing of the c ircu it. These studies were carried out on the ground w ith co llim a ted apparatus, the precise isoac tiv ity curves being traced a t d ifferen t dates.

The trend of activ ity in the area suspected of activation on account of the leak m ade possible d ifferentiation between that area and sectors suspect on account of cut-off piping or points of strong tracer adsorption.

A lead tank, situated in between two storeys, under the flooring of a room in which water was laid on, was intended to c o lle c t w ater com ing from possible leaks in the hydraulic insta llations above. In order to determ ine leakage from the tank, w ater labelled with Na24 was added to it. D ifficulty in tracing was caused by the super-position of patches of ac tiv ity up - and downstream of the leak , as w ell as by the la t te r ’s low ra te o f flow, which was estim ated a t 1 c m 9/m in .

An exact plot of the trend o f the activ ity , using isoactivity curves, m ade it possible to locate the leak

w ithin 15 h.A p re lim inary study, for the purpose of determ ining possible leakage of the order of 1 1/h betw een a

water-cooling circuit and a cellulose aceta te circuit whose flow-rates were known to be of the order of 5 m s/h , m ade i t possible to fix th e m ax im um tra n s it- tim e for waves of ac tiv ity in each o f fhe two c ircu its .

It was concluded tha t the leak could be revealed by in jecting 15 m e of Na24 into the water c ircu it and rem oving 3 1 o f a ce ta te over a period o f 20 m in . The coun t-ra te for this ac tiv ity and for an a liquot part of the to ta l activ ity in jec ted , counted in the sam e geom etry , indicated the leakage rate.

The "tw o-peak method" was adopted for measuring the flow-rate of water in a closed circuit. Circulation was carried out by a therm o-siphon, operating at 35Q*C and a pressure of 180 kg/cm 2. A single shot of 0 .5m c of Na24 in the form of carbonate was carried out and measurement of the tim e of transit of the wave of activity betw een two co llim ated sc in tilla tion detectors indicated the flow -rate with a re la tive accuracy of approxim ate ly 2%

APPLICATIONS DU SODIUM~24 A DES MESURES DE DEBITS ET DE RECHERCHES DE FUITES. Les auteurs décrivent en prem ier lieu quelques expériences où le sodium -24 a é té utilise afin de supprimer les problèmes, de décontam ination e t afin de pouvoir répéter les injections de traceurs. L*irradiation de sodium a é té faite dans le réacteur piscine « M é lu s in e » du C entre d 'é tudes nucléaires de Grenoble .

Pour dé tecte r une fuite sur un circuit de chauffage central, le circuit d 'eau a été marqué avec du carbona te de sodium m arqué au MNa. Un plan précis des canalisations a é té fa it afin de lim ite r les zones de re cherche après vidange e t rinçage du c ircu it. Ces recherches ont é té effectuées sur le sol avec des appareils co llim ates, en traçan t à différentes dates des courbes précises d 'isoac tiv ité ,

L*evolution dans le tem ps de la zone d 'a c tiv ité suspecte due à la fuite a perm is de la discrim iner des zones suspectes dues aux tuyaux en a tten te ou aux points de forte adsorption du traceur.

Une cuve d 'é ta n ch éité en plom b, située entre deux étages, sous le carre lage d ‘une salle d 'e a u , é ta it destinée à recu e illir les eaux provenant des fuites éventuelles dans les installations hydrauliques de l 'é ta g e supérieur.

•En vue de determ iner une fuite dans cette cuve, de l 'ea u marquée au 24Na a é té in jec tée sur la cuve. La difficulté de la recherche é ta it causée par la superposition des taches d 'a c tiv ité en am ont e t en aval de la fuite, ainsi que par le faible débit de cette dernière estim é â 1 cm* /m in .

383

384 J. GUIZERIX et R. CORNUET

Un tracé précis de l'évolu tion de la tache d 'a c tiv ité à l'a ide de courbes d 'isoactiv ité a permis, en 15 h, de déterm iner la position de la fuite.

Dans le but de déterm iner une fuite éventuelle de l'ordre de 1 l /h entre un circuit d 'eau de refroidissement e t un c ircu it d 'a c é ta te de cellulose dont les débits sont connus e t de l'o rdre de 5 m * /h , une étude préalable a perm is de fixer les tem ps de transit m axim um des vagues d 'a c tiv ité s dans chacun de ces c ircu its .

Cto en a déduit que cette fuite peu t ê tre mise en évidence en in jec tan t dans le c ircu it d 'e au 15 m e de ^ N a , e t en prélevant 3 1 d 'a c é ta te pendant 20 m in. Le taux de com ptage de ce tte a c tiv ité e t c e lu i d 'une partie aliquote de l 'ac tiv ité* to ta le in jec tée , com pté dans la m êm e géom étrie , perm etten t de déterm iner le débit de la fuite.

La « m é th o d e des deux p ic s » a é té utilisée pour m esurer un débit d 'e au dans un circuit ferm é; la c ir culation est réalisée par un thermosiphon, fonctionnant sous 350°C à une pression de 180 k g /c m 2. Une in je c tion quasi-ponctuelle de 0 ,5 m e de 24Na sous l»a forme de carbonate a é té réalisée e t la mesure du tem ps de transit de la vague d 'a c tiv ité entre deux détecteurs à scintillations collim atés a perm is de déterm iner le débit- avec une précision voisiñe áe 2%,

ИСПОЛЬЗОВАНИЕ НАТРИЯ-24 ПРИ ИЗМЕРЕНИЯХ ПОТОКОВ И ИССЛЕДОВАНИЯХ УТЕЧКИ. Авторы описывают

некоторые опыты, в которых в качестве индикатора использовался натрий-24 с целью исключения проблемы дезактивации и повторного введения индикаторов. Облучение натрия было произведено в бассей

новом реакторе "Мелюзин" в Исследовательском ядерном центре в Гренобле (Фракция).С целью исследования утечки в системе центрального отопления водяная система метилась карбонатом натрия-24. После очищения и промывки системы была составлена тщательная схема исследуемого уча с т-. к а , ограничивающая зону исследования. С помощью коллимированных приборов исследовалась почва, точные кривые иэоактивности исследовались для получения различных данных.

Обусловленное утечкой превращение в зависимости от времени исследуемой зоны радиоактивности позволило выделить его на фоке исследуемых зон в районе неподвижных труб или в местах сильного поглощения индикатора.

Исследовалась утечка на герметически закрытом свинцовом баке. Этот бак помещался между двумя ярусами, под настилом резервуара с водой, и был предназначен для сбора воды, которая могла появиться в результате возможной утечки в гидравлических установках, расположенных в верхнем ярусе. В бак вводилась вода, меченная изотопом натрия-24. Наложение радиоактивных пятен в нижней и верхней частях утечки, а также слабый выход потока, оцениваемого в 1 см3/мин, вызвали известную трудность в исследовании, и только четкое местоположение и рост радиоактивного пятна позволили при помощи кривых иэоактивности за 15 часов определить положение утечки.В целях определения возможной утечки порядка 1 л/час, которая имеет место между системой водяного охлаждения и системой ацетата целлюлозы, потоки которых известны и составляют примерно 5 м3/ч а с , предварительно проведенное исследование позволило установить время максимального пробега радиоактивных волн в каждой из этих систем.

Из этого был сделан вывод о том, что данная утечка может быть выявлена путем инъектирования в водяную систему 15 милликюри натрия-24, и извлечения 3 л ацетата в течение 20 мин. Число отсчетов этой активности, отнесенное к полной активности инъектированной воды, которая подсчитывалась при той же геометрии, позволяет определять утечку.

Для измерения потока воды в замкнутой системе был применен "метод двух максимумов"; циркуляция б и л а осуществлена при помощи термосифона, работающего при температуре 350°С и давлении 180 кг /с м 2 . Была применена квазиточечная инъекция натрия-24 (0 ,5 милликюри) в виде карбоната; при этом измерение времени пробега радиоактивной волны между двумя коллимированными сцинтилля- ционными детекторами позволило определить поток с относительной точностью, примерно равной 2%.

APLICACIONES DEL SODIO-24 A LA MEDICION DE CAUDALES Y DETECCION DE ESCAPES. Los autores describen en prim er lugar algunas experiencias en las que se ha utilizado sodio-24 a fin de evitar los problemas de descontam inación y poder repetir las inyecciones de indicadores. El sodio se ha irradiado en e l reactor de piscina "M élusine" d e l Centre d 'études nucléaires de Grenoble.

En e l circuito de agua se ha inyectado carbonato de sodio m arcado con MNa, con e l objeto de descubrir escapes en un c ircuito de calefacc ión cen tra l. Se ha trazado un plano exac to de las canalizaciones a fin de lim ita r las zonas de investigación, después de haber vaciado y lim piado e l circuito . Estas investigaciones se

APPLICATIONS DU SODIUM-24 A DES MESURES DE DEBITS 385

han efectuado sobre e l suelo con aparatos colimados, trazando en diferentes fechas curvas precisas de isoac ti- vidad.

La evolución en e l tiem po de la zona de activ idad , en la que se cree que se han producido escapes, ha perm itido distinguirla de las zonas sospechosas debido a las tuberías o a los lugares de fuerte adsorción de l indicador.

Un depósito de plom o estanco, situado en tre dos pisos, debajo de las baldosas de un cuarto de aseo, estaba destinado a recoger las aguas procedentes de los posibles escapes en las instalaciones h idráulicas de l piso superior.

A fin de determ inar los escapes, se ap licó sobre e l depósito agua m arcada con 24Na« La d ificu ltad de las investigaciones se debe a la superposición de las manchas de activ idad a la en trada y salida de l escape, asi com o a l bajo caudal de d icho escape, que era de 1 cm s /m in .

Por análisis exac to de la evolución de la m ancha de actividad m ediante curvas de isoactividad, se ha podido determ inar en 15 h e l lugar en que se había producido e l escape.

Con e l propósito de determ inar los posibles escapes de l orden de 1 1/h entre un c ircuito de agua de r e frigeración y un circuito de aceta to de celulosa, cuyos caudales conocidos son del orden de 5 m 3/h , un estudio p re lim inar ha perm itido fija r e l tiem po de tránsito m áxim o de las ondas de activ idad en cada uno de esas c ircuitos.

Se ha comprobado que un escape de esa. índole puede detectarse inyectando en un circuito de agua 15 me de MNa, y extrayendo 3 1 de a ce ta to durante 20 m in. El caudal del escape puede determ inarse m ediante e l índice de recuento de esta activ idad y e l de una parte alícuota de la actividad to ta l inyectada, determ inada en las mismas condiciones geom étricas.

Se ha u tilizado e l "m étodo de los dos m áximos" para m edir e l caudal de agua en un c ircuito cerrado; la c ircu lación se obtiene m edian te un term osifón, que funciona a 350#C a una presión de 180 k g /c m 2. Se efectuó una inyección cuasi-puntifórm e de 0, 5 m e de carbonato de sodio m arcado con 24Na; la m edición del tiem po de transito de la onda de actividad entre dos detectores de centelleo colimados perm itió determ inar e l caudal con una precisión relativa del 2%, aproximadamente.

L e s ap p lic a tio n s de t r a c e u r r a d io a c ti f , qui von t ê t r e d é c r i te s , donnent l ie u s o i t à l a d is p e r s io n d 'a c t iv i té d an s l e s eau x in d u s t r ie l le s u s é e s , s o i t à l a f ix a tio n de c e tte a c tiv i té ou à l a s ta g n a tio n d 'ea u m a rq u é e a p rè s u sa g e , d an s un m il ie u m a l d éfin i a p r io r i e t f a is a n t p a r t ie d 'u n e a i r e in d u s t r ie l le , ou d ’une m a n iè r e g é n é ra le en c o n ta c t avec la popu la tion .

Il im p o r ta it donc de fa ire appel à un tr a c e u r ra d io a c tif de co u rte p é r io d e p ro p re à s 'é l im in e r p a r s a s e u le d é c ro is s a n c e , év itan t de ce fa it une o p é ra t io n de d é c o n ta m in a tio n qu i s e r é v é la i t im p o s s ib le . C e fu t l 'u n e d e s p r e m iè r e s r a i s o n s du ch o ix du s o d iu m -2 4 p o u r n o s e s s a i s . P a r a i l l e u r s s a c o u r te v ie p e r m e t , d 'u n e p a r t , de re c o m m e n c e r év e n tu e lle m e n t le s e s s a is e t , d 'a u t r e p a r t , c o n tr ib u e à lu i d o n n e r un e c o n c e n tra t io n m a x im u m a d m is s ib le d a n s l 'e a u é le v é e .

Son ra y o n n e m e n t d u r p r é s e n te s o it un a v a n ta g e , s o i t un in c o n v én ie n t. Un av an tag e , p a r ex e m p le , p o u r le s r e c h e rc h e s de fu ite , lo rsq u e le s é p a is s e u r s de m a té r ia u x à t r a v e r s e r p a r le ra y o n n e m e n t s o n t im p o r ta n te s ; u n in c o n v é n ie n t, c a r i l im p o s e l 'u t i l i s a t io n de c o l l im a te u r s e n p lo m b a s s e z lo u r d s a f in de f a i r e d e s m e s u r e s a s s e z lo c a l i s é e s .

On c o n n a ît m a l s e s p r o p r ié té s de f ix a tio n p a r a d s o rp tio n s u r l e s d if f é re n ts m a té r ia u x . D ans le c a d re de nos e s s a is , cep en d an t, oû il fu tu t i l is é av ec de la r g e s q u a n tité s d 'e n t r a în e u r , ce phénom ène n 'a p a s é té une g êne .

C e t r a c e u r e s t f a b r iq u é p a r i r r a d i a t i o n d a n s le r é a c t e u r « p i s c i n e » M élusine du c e n tr e d 'é tu d e s n u c lé a ire s de G ren o b le , en g é n é ra l pendant une nu it.

386 J. GUIZERIX et R CORNUET

1. RECHERCH ES DE FU ITES

L e s r e c h e r c h e s de fu ite s à l 'a i d e de t r a c e u r s r a d io a c t i f s se lo n l a m é th o d e q u i c o n s is te à m a rq u e r l 'e a u de l 'e n c e in te p r é s e n ta n t l a fu ite , -à v id a n g e r c e tte d e r n iè r e e t à r e c h e r c h e r l e s ta c h e s d 'a c t iv i té p ro d u ite en ava l de l a fu ite , s ' a v è re n t ê t re le s p lus s im p le s e t e l le s so n t devenues c la s s iq u e s .

C ependan t, à n o tre s e n s , l a r e c h e rc h e d es ta c h e s a n o rm a le s d 'a c tiv ité d o it d é p a s s e r le s ta d e ^l'une r e c h e r c h e du ty p e to u t - o u - r i e n . E n e f fe t, l 'é v o lu tio n de l 'e a u m a rq u é e en av a l de l a fu ite p eu t s e f a i r e , p a r ex em p le , le long de l a c a n a l is a t io n qu i, b ie n que v id a n g ée de l 'e a u a c tiv e , p eu t ê t r e lé g è r e m e n t co n ta m in é e e t, p a r là , g ê n e r la r e c h e r c h e . Ou b ien e n c o re , i l p e u t r e s t e r de l 'e a u a c tiv e d an s u n p o in t b a s ou d an s un e c a n a l is a t io n e n a t te n te ; i l c o n v ie n t donc de p o u v o ir d i s c r im in e r c e s d eu x s i tu a t io n s .

D an s n o tr e p r e m i e r e x e m p le n o u s d é c r iv o n s u n e m é th o d e que n o u s app liq u o n s d 'u n e m a n iè r e sy s té m a tiq u e p o u r l a r e c h e r c h e d es fu ite s de ce type . E lle c o n s is te à su iv re l 'év o lu tio n dans le tem p s de tou te tache anorm ale d 'a c t iv i té en t r a ç a n t des c o u rb e s d 'is o a c tiv i té à l 'a id e d 'u n a p p a re il p o r ta t if c o l l im a té . C e t a p p a re i l c o n s ti tu é d ' u n d é te c te u r à s c in t i l la t io n s , e s t r e p ré s e n té à l a f ig u re 1. L a f ig u re 2 r e p r é s e n te u n d eu x ièm e type d 'a p p a re i l , qui p e r m e t d ' e x p lo re r le s p la fo n d s ou le s m u rs .

A ppareil m obile pour exploration au sol.

1 .1 . R e c h e rc h e de fu ite s u r un c i r c u i t de chau ffage c e n tr a l

L e s in s ta l la t io n s de ch au ffag e c e n t r a l r e p r é s e n te n t u n e s i tu a tio n t r è s fa v o ra b le aux r e c h e r c h e s de fu ite s , p a rc e que, d 'u n e p a r t , i l s 'a g i t de c i r c u i ts i s o l é s d e s r é s e a u x d 'a l im e n ta t io n en e a u , e t que , d 'a u t r e p a r t , u n e

APPLICATIONS DU SODIUM-24 A DES MESURES DE DEBITS 387

Figure 2

Ensemble m obile pour exploration des plafonds e t des murs.

bonne r é p a r t i t io n du t r à c e u r dans l 'in s ta l la t io n peu t ê tre effec tuée en m e ttan t en m a rc h e l 'a p p a re i l de chauffage.

Nous c ito n s 1' exem ple typique d 'une in s ta lla tio n d 'une cap ac ité de 1 5001, d an s la q u e lle une in je c t io n de 10 m e de 2*Na fu t e ffe c tu é e so u s l a fo rm e de c a rb o n a te av ec une q u a n tité 1 000 fo is s u p é r ie u r e en m a s s e de s e l in a c ti f e n t r a în e u r .

Au c o u rs d 'u n e p r e m iè r e p h a se a p rè s h o m o g é n é isa tio n du c i r c u i t , un r e le v é ra p id e du p la n d es c a n a lisa tio n s a é té r é a l is é . C e tte ph ase e s tn é c e s - s a i r e afin de l im i te r le s zones de re c h e rc h e c a r l 'e x p é r ie n c e m o n tre q u 'il ne fau t s e f ie r q u 'av ec p ru d en ce aux p lans é tab lis p a r le s in s ta lla te u rs .

P e n d a n t l e s p h a s e s s u iv a n te s on a v id an g é l 'in s ta l l a t io n e t on a : r in ç é - l e s c i r c u i t s .

C e r te s le te m p s c o n s a c ré à c e s d iv e rs e s o p é ra tio n s e s t un fa c te u r im p o r ta n t . Une m is e en c h a rg e de l a fu ite p eu t p ro v o q u e r une d is p e rs io n tro p im p o r ta n te du t r a c e u r , e t a in s i , d im in u e r l a p r é c is io n de lo c a l i s a t io n de l a fu ite . Un r in ç a g e tro p long peu t donner lie u à une d ilu tion tro p im p o rta n te de l 'a c t iv i té en av a l de l a fu ite . Il e s t donc im p o rta n t d 'e s t im e r l 'im p o r ta n c e du d éb it de l a fu ite .

D ans l 'e x e m p le donné, le s co u rb e s d 'iso a c tiv ité , à peu p rè s c irc u la ire s , on t to u t d 'a b o rd au g m en té de d ia m è tre . P u is , p en d an t e t a p r è s l a p h a se de r in ç a g e , ont d im in u é de d ia m è tre . E l le s é ta ie n t d û es à un é c o u le m en t dans le t e r r a i n so u s une p iè ce du r e z - d e Ach au ssée : l 'é v o lu tio n des co u rb e s d 'is o a c t iv i té c o r r e s p o n d a i t à u n e d if fu s io n , à u n la v a g e e t à u n é c o u le m e n t de l a s o lu tio n m a rq u é e .

1 . 2 . R e c h e rc h e de fu ite s u r un e cu v e d 'é ta n c h é i té

A p rè s l ’ex em p le c la s s iq u e que nous avons d é c r i t , nous èn avons c h o is i u n a u tre p o u r i l l u s t r e r l 'im p o r ta n c e de la c o n n a issa n ce p r é c is e de l 'é v o lu tio n de l a ta c h e d 'a c tiv ité dans le te m p s com m e fa c te u r de r é u s s i te .


L a re c h e rc h e en ques tion a é té r é a l is é e s u r une cuve d 'é ta n c h é ité , cons t i tu é e d 'u n e fe u il le de p lom b de 3 m m d 'é p a is s e u r , e n c a s t r é e dans l e so l d 'u n e s a l l e d 'e a u a y a n t u n e c in q u a n ta in e de m ë t r e s c a r r é s e t d e s t in é e à r e c u e i l l i r l e s eau x ré p a n d u e s s u r un s o l en c a r r e a u x de g r è s r é p u té non é tan ch e (fig. 3). L e s g o u ttiè re s au p lafond de l 'a t e l i e r s e tro u v a n t à l 'é ta g e in f é r ie u r p e r m e t ta ie n t d 'e s t im e r le d éb it de la fu ite à e n v iro n 1 cm 3/m in .

Figure 3

Coupe de la sa lle d 'e au .

U n c a r r e a u a y a n t é té e n le v é , u n e in je c t io n de t r a c e u r a é té r é a l i s é e d ans l a c a v ité c o rre sp o n d a n te , pu is le « c i r c u i t am on t» a é té m ise en ch a rg e , d an s une p a r t ie de l a s a l le , is o lé de l 'e n s e m b le , en ré p a n d a n t de l 'e a u s u r l e c a r r e la g e .

C e tte s i tu a tio n é ta i t peu fa v o ra b le à une r e c h e r c h e de fu ite . E n e ffe t, l 'e a u é ta n t m a rq u é e avec du 2*N a, nous d ev ions nous t r o u v e r en p ré s e n c e d 'u n e ta ch e d 'a c tiv i té en am on t de la fu ite , e t d 'une ta ch e en ava l, c e s deux ta c h e s pouvant s e s u p e rp o s e r .

T ro is in je c tio n s de 1 e t 2 m e avec e n tra în e u r fa ite s en t r o is po in ts d iff é r e n ts o n t é té n é c e s s a i r e s ; l e s f ig u re s 4 e t 5 m o n tr e n t l 'é v o lu t io n de l a ta c h e d 'a c tiv i té . L 'in te rp ré ta t io n de c e s co u rb e s s e r a i t tro p longue à r e la te r ic i , m a is e lle nous a am ené à p ré s u m e r l 'e x is te n c e d 'une fu ite dans l a zone h a c h u ré e . L a fu ite fu t e ffec tiv e m en t d éco u v erte dans c e tte zone, a p rè s 15 h de m e s u r e s .

A vec n o tr e t r o i s i è m e e x e m p le , n o u s -e n tro n s d an s lé d o m a in e de l a m e s u re du d éb it d 'u n e fu ite , la p o s itio n m ê m e de la fu ite n 'a y a n t p as d 'im p o r ta n c e . C e s e r a l e c a s d e s é c h a n g e u rs de t e m p é r a tu r e , p a r e x e m p le , où l a p ré s e n c e d 'u n e fu ite im p o se .le re m p la c e m e n t de l 'e n se m b le in c rim in é ou to u t au m o in s son dém ontage à des fin s de ré p a ra tio n .

APPLICATIONS DU SODIUM-24 A DES MESURES DE DÉBITS

Figure 4

Courbes d 'iso ac tiv ité « re c h e rc h e de fu ite sur cuve d 'é ta n c h e ite »

?¡U2® INJECTION 10 h 00 _ l e INJECTION 23h00

fЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧЧчЧЧЧЧЧЧЧЧЧЧЧчЧЧЧЧЧЧЧЧччч^Л^ЧЧчЧчЧЧЧЧЧЧЧЧЧЧЧчЧчЧЧЧЧчЧЧччЧЧЧччч■г

Figure 5

C ourbet d 'iso ac tiv ité « re c h e rc h e de fu ite sur cuve d 'é ta n c h é ité » .


1. 3. D é te rm in a tio n d 'u n d éb it de fu ite dans un m a la x e u r éch an g eu r de te m p é ra tu re

L e c i r c u i t en v isag é e s t c o n s titu é d 1 une en ce in te cy lind rique dans laq u elle c i r c u le de l 'a c é ta te de c e llu lo se . Au c e n tr e de c e tte en c e in te , dans un tuyau m u n i de p a le t t e s e t a n im é d 'u n m o u v e m e n t a l t e r n a t i f de t r a n s l a t i o n e t de r o ta t io n c i r c u le de l 'e a u ; 'l 'e n s e m b le c o n s titu e un m a la x e u r - é c h a n g e u r de te m p é r a tu r e .

I l a r r iv e que le tuyau c e n tr a l s e c o rro d e e t se p e rc e ; i l e s t in té re s s a n t a lo r s de p o u v o ir e f fe c tu e r d e s c o n trô le s p e rm e tta n t de m e t t r e en év id en ce un e fu ite de l 'o r d r e de 1 l / h d 'e a u dans le c i r c u i t d 'a c é ta te .

E n in je c ta n t une ac tiv ité Ai dans le c i rc u it p r im a ire e t s i Аг re p ré s e n te l 'a c t iv i té p a s s a n t dans le c i r c u i t s e c o n d a ire , Q i le d éb it du c i rc u it p r im a ire e t f c e lu i de l a fu ite , no u s pouvons é c r i r e l a r e la t io n A 2/A i = f / Q i en su p -

Tp o s a n t que / c d t = c o n s ta n te p o u r to u s le s p o in ts de la s e c tio n , c é ta n t la

oc o n c e n tra tio n à l 'in s ta n t t en un p o in t de la se c tio n e t T le te m p s de p assag e de l a vague d 'a c t iv i té en ce po in t.

C o n n a is sa n t Q i, on en d é d u ira f à co n d itio n de p o u v o ir é v a lu e r le r a p p o r t

Ag/Aj.

U ne p r e m iè r e m éthode p o u r é v a lu e r ce r a p p o r t p eu t c o n s is te r à p la c e r u n d é te c te u r c o n tre l a c a n a l is a t io n s e c o n d a ire en av a l du m é la n g e u r , pu is à e x p lo ite r le n o m b re de coups e n r e g is t r é au p a s sa g e de la vague d 'a c tiv ité , e n ap p liq u an t l e s r e la t io n s de l a « m é th o d e du n o m b re to ta l de coups » , d é c r i t e p a r H U LL [1] .

IL fau t e n c o re que l a cond ition J cd t = co n s tan te so it re m p lie au vo isinageo

du d é te c te u r ; de p lu s , un é ta lo n n a g e en r é g im e s ta t iq u e , d an s un e p o r tio n de c a n a l is a t io n id e n tiq u e à l a p o r t io n v o is in e du d é te c te u r e s t n é c e s s a i r e .

Nous p ré fé ro n s une m éthode de p ré lè v e m e n t d 'a c é ta te en ava l du c irc u it s e c o n d a ir e , m é th o d e qu i p e r m e t , e n p a r t i c u l i e r , d 'u t i l i s e r u n e a c t iv i té m o in d re .

A p p e lo n s q 2 l e d é b i t d 'u n p r é lè v e m e n t co n tin u e n u n p o in t du c i r c u i t s e c o n d a ir e , e f fe c tu é p e n d a n t le p a s s a g e de l a v a g u e d 'a c t iv i té .

L 'a c t iv i té co n ten u e d an s ce p ré lè v e m e n t e s t a i = A2 q2/Q 2 , à co n d itio n

que la r e la t io n J cd t = co n s tan te s o it r é a l is é e dans l a se c tio n du p ré lèv em en t, o

L e com ptage de ce p ré lè v e m e n t donne un n o m b re de coups N i. L e com pta g e d 'u n e a c t iv i té é ta lo n a2 donne u n n o m b re de co u p s N2 • N ous avons la r e la t io n su iv a n te :

APPLICATIONS DU SODIUM-24 A DES MESURES DE DÉBITS 391

e t

Ai _ ¿2 Ni Q2 A2 A j Щ q 2

L e r a p p o r t e s t d é te rm in é en la b o r a to i r e .

D ans le c i r c u i t e n v isag é , un e s s a i p r é l im in a i re nous a p e rm is , à p a r t i r de deux in je c t io n s p o n c tu e lle s e f fe c tu é e s en am o n t d e s c i r c u i t s p r im a i r e s e t s e c o n d a ire s , de c o n n a î t r e l e s te m p s de t r a n s i t du f ro n t d 'a c t iv i té d an s c h a c u n de c e s c i r c u i t s , a in s i que l a l a r g e u r de l a v ag u e d 'a c t iv i té . On en a d é d u it l e s d a te s de d éb u t e t de fin d e s p ré lè v e m e n ts p e n d a n t l e p a s s a g e é v e n tu e l d 'u n e v a g u e d 'a c t iv i té due à un e fu ite en u n p o in t q u e lc o n q u e du c i r c u i t p r im a i r e .

L e s d é b its é ta n t de 5 m3 dans le s deux c i r c u i t s , nous avons é ta b li que 15 m e de '^ N a é ta ie n t n é c e s s a i r e s à c e s o p é ra t io n s d e c o n t rô le p o u r m e t t r e e n é v id e n c e u n e fu ite de 1 l / h .

N ous u ti l is o n s , com m e dans l a p lu p a r t de nos ap p lica tio n s de t r a c e u r s , un d é te c te u r à s c in ti l la t io n s .

N ous c i te r o n s , p o u r te r m in e r , un ex e m p le d 'a p p lic a tio n d e '^ N a , dans le q u e l e n c o re l a c o u r te p é r io d e de ce t r a c e u r p r é s e n ta i t un in té r ê t p o u r son au to - déco n tam in a tio n .

2. M ESURE DE D ÉBIT SUR THERM OSIPHON H A UTE-PRESSION

L e c i r c u i t s u r le q u e l c e tte m e s u re a é té e ffec tiv e é ta i t c o n s titu é d 'u n e boucle fe rm é e s u r e l le -m ê m e , dans la q u e lle c i rc u la i t de l 'e a u à 180 kg /cm ? & u n e te m p é r a tu r e de 350°C , s o u s l 'a c t io n d 'u n th e rm o s ip h o n . C e c i r c u i t c o n s titu a it un e c e llu le d 'e s s a i de c o r ro s io n , p o u r la q u e lle l a c o n n a is sa n c e du d é b it é t a i t u n f a c te u r im p o r ta n t . U ne m é th o d e th e rm iq u e p e r m e t ta i t d 'a t t e in d r e t r è s in d i r e c te m e n t c e d é b it; c 'e s t p o u rq u o i, i l fu t d é c id é d 'u t i l i s e r l a m éthode du « p ic tim in g » pou r v é r i f ie r l a v a lid ité de l a m éthode th e rm iq u e .

L e c i r c u i t a v a it u n e c a p a c i té de 20 1 e n v iro n , e t l e s c a n a l is a t io n s un d ia m è tre de 20 m m . N ous avons in je c té 0 ,5 m e de 24Na, à l 'a i d e d 'u n d is p o s it if c o m p re n a n t u n e ja u g e d 'e s s a i de p r e s s io n .

Ce d isp o s itif e s t r e p r é s e n té à l a f ig u re 6. Il co m p ren d un . s a s de 10 cm 1 c o n s ti tu é p a r u n tu b e e n U. L e s v a n n e s 2 e t 3 p e r m e t te n t d 'in t r o d u i r e l a so lu tio n a c tiv e , to u t en m én ag ean t dans chaque b ran c h e une b u lle d 'a i r . C es v a n n e s é ta n t f e r m é e s , on m e t ta i t l 'e n s e m b le s o u s p r e s s io n à l 'a i d e de l a pom pe H P a p rè s a v o ir o u v e r t l a vanne 4 . L 'in je c tio n é ta i t e n su ite r é a l i s é e p a r l a p o m p e H P a p rè s a v o ir o u v e r t l a v an n e V . L e r ô le d e s deux b u lle s d 'a i r é ta i t im p o rta n t; i l p e rm e tta i t d 'é v ite r la d iffusion du p ro d u it dans l 'e a u de la pom pe ou v e r s le c irc u it .

L 'in je c t io n de 10 cm 3 de s o lu tio n a c tiv e d u r a i t q u e lq u e s d ix iè m e s de se c o n d e . D eux d é te c te u r s à s c in t i l la t io n c o l l im a té s é ta ie n t p la c é s s u r une b a s e de 2 m .

L e s deux p ic s d 'a c t iv i té e n r e g i s t r é s é ta ie n t p ra t iq u e m e n t id e n tiq u e s e t l ’on a pu é v a lu e r l ' e r r e u r de m e s u ré du d é b it à 2%.


VANNES 1 ET t, : INJECTION

Figure 6

Dispositif d ’ in jec tion du traceur dans la ce llu le HP.

R É F É R E N C E

Ш HULL, D. E. e t FRIES, B. A ., Actes Conf. in t. u til. EAFP (ONU) XV (1956) 236.

EMPLOI DU MNa COMME TRACEUR DANS LES TRAVAUX ÉDILITAIRES ET HYDROLOGIQUES

E. GASPAR, M. ONCESCU, P. SANDRU, L. GRIGORESCU, M. BIRNBAUMET T. TEITEL

INSTITUT DE FIZICÂ ATOMICA, BUCAREST, ROUMANIE


THE USE OF Na24 AS A TRACER IN PUBLIC WORKS AND HYDROLOGY. T he authors review th e work of the Institute of Atomic Physics in Bucharest in the application of short-lived radioisotopes in hydrology. Such work includes de term ination of fluid loss from m ain w ater-p ipes and investigation of infiltra tions n to barrages.

The páper deals principally with the determ ination of the d irection and flow veloc ity of subterranean waters through a sandy m edium , rich in o rganic substances, s ituated on the shore of the Black Sea.

A solution of NOjLa140 and Na**Cl, of which the activ ity was about 50 m e, was used to which inactive m ateria l was added. The choice of La and Na cations was determ ined by the absence of clayey m ateria l from the m edium studied.

The solution was introduced into a central w ell, and its passage through other neighbouring wells, spaced at distances of 1-5 m , was detected using submersible Geiger-M tiller counters. The operation was repeated in several places w ithin the region studied.

The activ ity to be used was calcu la ted , taking into account the effic iency of the detection apparatus, the dimensions of the portions of ground studied, the estim ated value of the flow velocity , the eventual absorption of th e tra c e r by the ground, and the m axim um perm issible levels of the radioisotopes in w ater.

The results o f the work have shown the inconsistency of one of the presently-held hypotheses in connection with the soiling by industrial residues of a fresh-w ater lake situated in the vicinity.

EMPLOI DU 24Na COMME TRACEUR DANS LES TRAVAUX ÉDILITAIRES ET HYDROLOGIQUES. Les auteurs passent en revue les travaux effectués à l'Institu t d 'études atom iques de Bucarest dans le dom aine de l 'app lica tion des radioisotopes de courte période en hydrologie. Ces travaux portent notam m ent sur la d é te rm ina tion des fuites dans les cana lisa tions d 'e a u p rinc ipa les, e t des in filtra tions dans les barrages.

Dans leur m ém oire les auteurs décrivent principalem ent les recherches qu'ils sont faites pour déterm iner la d irection e t la vitesse d 'écoulem ent d 'eaux souterraines à travers un m ilieu sablonneux, riche en substances organiques, situé sur les bords de la Mer Noire.

Us ont u tilisé à c e t effe t une solution de NOsM0La e t d e 24N aCl, dont l 'a c tiv ité é ta it d 'environ 50 me e t à laquelle on avait ajouté de la m atière inactive. Le choix des cations La e t Na a é té déterm iné par l 'a b sence de toute substance argileuse dans le m ilieu étudié.

La solution a é té in troduite dans un puits cen tra l; son passage à travers des puits voisins, situés à une d istance de 1 à 5 m les uns des autres, a é té dép isté à l 'a id e de com pteurs G eiger-M U ller subm ersibles.

L 'opération a é té répé tée en plusieurs endroits de la région considérée.Les auteurs ont c alcu lé l 'a c tiv ité à u tiliser, en tenan t com pte de l 'e f f ic a c ité de l 'ap p a re il dé tecteu r,

des dimensions des portions de terrain étudiées, de la valeur estim ative de la vitesse d 'écou lem ent, de l 'a b sorption finale du rad io ind icateur par le sol e t des concentrations m axim um s adm issibles des radioisotopes dans l 'e a u .

Les résultats de c e tte étude ont dém ontré l'inconsistance de l'hypothèse qui avait é té avancée sur la con tam ination , par des résidus industriels, d 'un lac d 'e a u douce situé dans le voisinage.

ИСПОЛЬЗОВАНИЕ Na24 В КАЧЕСТВЕ ИНДИКАТОРА В СИСТЕМЕ КОММУНАЛЬНЫХ СООРУЖЕНИЙ И В ГИДРОЛОГИЧЕСКИХ РАБОТАХ. Дается обзор работ, выполняемых в Институте атомной физики в Бухаресте, по применение короткоживущих радиоизотопов в гидрологии. Работы включают определение утечки при испытании водопроводных труб и просачивания воды через плотины.

Основная часть доклада посвящена методам определения-направления и скорости потока подземных вод через песчаную среду, богатую органическими веществами, на побережье Черного моря.

393

394 E. GASPAR et al.

Использовался раствор N03La14° и Na24Cl активностью 50 ик с добавлением неактивного материал а . Выбор катионов La и Na определялся отсутствием глинистого м атериала в изучаемой ср ед е .

Раствор вводился в центральный колодец, с помощью счетчиков Гейгера-Мюллера определялось его прохождение через соседние колодцы, удаленные друг от друга на 1 - 5 м.

Операция была повторена в нескольких местах изучаемого района. Активность рассчитывалась с учетом эффективности регистрационных приборов, размеров участков изучаемой земли, вычисленной величины скорости потока, возможного поглощения индикатора почвой и максимального допустимого содержания радиоизотопов в воде.

Результаты работы подтвердили несостоятельность одной их недавних гипотез о загрязнении расположенного поблизости чистого озера промышленными отходами.

EMPLEO DEL COMO INDICADOR EN TRABAJOS DE CONSTRUCCIÓN E HIDROLOGIA. La memoria revisa los trabajos que se rea lizan en e l Instituto de Física Atóm ica de Bucarest sobre aplicaciones de rad io isótopos de período corto en hidro logía. Entre otras cosas, se han determ inado pérdidas de liquido en con* ducciones de agua y se han investigado las infiltraciones en em balses.

Se em pleó una solución de i^LaN O s У de 24NaCl con una activ idad aproxim ada de 50 m curies, a la que se aQadió m a te ria l inactivo . Se elig ieron los cationes La y Na en vista de la ausencia de m ateria les a r cillosos en e l m edio estudiado.

La solución se introdujo en un pozo centra l y su paso por otros pozos próximos se detectó con ayuda de contadores G eiger-M uller sumergibles situados a distancias de 1 a 5 m.

La operación se rep itió en varios lugares de la zona estudiada.La cantidad de radioisótopo se calcu ló teniendo en cuenta e l rendim iento de los aparatos de detección ,

las dimensiones de las zonas estudiadas, e l valor calculado para la velocidad de c irculación , la posible a b sorción d e l indicador por e l te rreno y los n ive les m áxim os adm isibles de radioisótopos en e l agua.

Los resultados d e l traba jo han dem ostrado que no es válida la hipótesis según la cual un lago de agua dulce situado en las proxim idades se está contam inando con residuos industriales.

1 . D É T E C T IO N D ES F U IT E S E T D ES N O N -É T A N C H E IT É S DANS L E SG R A N D E S C O N D U ITES P R IN C IP A L E S D* A D D U C TIO N D 'E A U

L e g ra n d e s s o r du l i t to r a l ro u m a in de la M e r N o ire a p o sé le p ro b lèm e d ’a u g m e n te r le d é b it d ’eau d an s la co n d u ite p r in c ip a le qu i a s s u r e l ’a l im e n ta tio n en eau p o ta b le d e v i l l e s s i tu é e s au v o is in a g e de la m e r .

M a is on ne p o u v a it a u g m e n te r le d éb it s a n s v é r i f i è r au p r é a la b le s i le f a i t d ’a c c r o î t r e la p re s s io n n ’a u ra i t p a s eu pou r effe t de p ro v o q u er d es fu ite s d u es à une m a u v a ise é tan c h é ité ou à des f i s s u r e s .

L a c o n d u ite , d ’un e lo n g u e u r de 23 k m , b â t ie en b é to n a r m é e t en tô le de G m m , d ev a it ê t r e v é r if ié e so u s une p re s s io n de 10 à 11 a tm . On p o u rra it l o c a l i s e r le tro n ç o n p o s s é d a n t d e s fu i te s p a r l e s m o y e n s c l a s s iq u e s m a is i l f a u d r a i t a u s s i lo c a l i s e r le s fu ite s d an s le tro n ç o n de 500 m ce qu i s e r a i t e x trê m e m e n t la b o r ie u x .

On s ’e s t p ro p o s é d ’e m p lo y e r d e s t r a c e u r s r a d io a c t i f s p o u r lo c a l i s e r l e s f u i te s .

On e s t a r r i v é à la m é th o d e su iv a n te : on in tro d u it d an s le tro n ç o n à v é r i f i e r u n e so lu tio n m a rq u é e p a r un ra d io is o to p e , on a u g m e n te la p r e s s io n d a n s la co n d u ite ju sq u ’à 10 ou 11 a tm e t on la m a in tie n t p en d an t un e h e u re ( f i g . l ) .

L a s o lu tio n m a rq u é e fu it en q u a n t i té s s u s c e p t ib le s d ’ê t r e d é te c té e s , m ê m e p a r l e s p e t i te s f i s s u r e s . A p rè s a v o ir é v a cu é l ’e a u , on p ro c è d e à un la v a g e de la co n d u ite a f in de la d é c o n ta m in e r de m a n iè r e g r o s s iè r e (fig . 2).

P o u r l o c a l i s e r le s f u i te s , on in tro d u it d an s la co n d u ite un a p p a r e i l d é te c te u r qu i, to u t en s ’y d é p la ç a n t, t r a n s m e t l ’in fo rm a tio n à un e n r e g is t r e u r g ra p h iq u e au m oyen d ’un c â b le (fig . 3).

24Na COMME TRACEU.R DANS LES TRAVAUX ÉDILITAIRES 395

Figure 1

Schéma des vannes e t des prises.

APPAREILENREGISTRATES

Figure 2 .

Déplacem ent du détecteur dans la conduite.

L e ra d io iso to p e a é té c h o is i de m a n iè re à s a t i s f a i r e le s co n d itio n s g é n é r a l e s a u s s i b ie n q u e l e s c o n d itio n s p a r t i c u l i è r e s à l ’e x p é r ie n c e . .

L e s c o n d itio n s g é n é r a le s c o n c e rn e n t l a s o lu b i l i té du s e l c o n te n a n t le r a d io is o to p e d a n s le f lu id e u t i l i s é à d e s f in s d e d é te c tio n , e t l a p ro te c t io n c o n tre l e s r a d ia t io n s ( s é c u r i té du p e r s o n n e l e t c o n ta m in a tio n é v e n tu e lle ) .

C e s co n d itio n s im p o s e n t le cho ix du 24Na, qu i so u s la fo rm e de 2fNaCl, e s t f a c ile m e n t so lu b le , é m e t d e s ra d ia t io n s d é c e la b le s m ê m e à t r a v e r s l a p a r o i d e l a co n d u ite e t, en o u tr e , p r é s e n te une p é r io d e r a d io a c t iv e s u f f is a m m e n t c o u r te (15 h).

C o m m e c o n d itio n p a r t i c u l i è r e , i l c o n v ie n t d e m e n tio n n e r l e f a i t q u e l e ra d io is o to p e d o it ê t r e r e te n u d a n s le l o e s s t r a v e r s é p a r l a c o n d u ite .

C om m e la c o n c e n tra tio n m in im u m d é c e la b le de l a so lu tio n ra d io a c tiv e e s t de 1 m c /m 3, i l fa u t ég a le m en t que le 24Na, d ’a c tiv ité é lev ée , p u is s e ê t re p ro d u it ra p id e m e n t e t su ffisa m m e n t bon m a rc h é .

C e tte cond ition à é té s a tis f a i te g ra c e à l ’a id e du r é a c te u r a tom ique ro u m a in .

396 b. GASPAR et al.

:LÓÉSSl

N» /BETON RENFORCÉ

CÂBLE JIOÉTECTEURH

CÂBLE

MOTEUR

Figure 3

Coupe longitudinale.

L ’a p p a r e i l d é t e c te u r c o n t iè n t t r o i s c o m p te u r s G e ig e r du ty p e C T C -6 m o n té s en p a r a l lè le e t d isp o sé s sy m é tr iq u em en t p a r ra p p o r t à l ’axe de l ’appa» r e i l . On a u t i l is é t r o i s p ile s de 4,5 V pour l ’a lim en ta tio n .

L ’a p p a r e i l , q u i e s t e n t iè r e m e n t t r a n s i s to r i s é , , e s t de p e t i te s d im e n s io n s ; l ’in fo rm a tio n e s t t r a n s m is e p a r un s e u l f i l (fig . 4).

L ’e n r e g is t r e m e n t du ta u x de co m p tag e s u r to u te la lo n g u eu r de la co n d u ite n o u s a p e r m is de l o c a l i s e r l e s f u i te s a v e c une bonne p r é c is io n : s o it à m o in s d ’un m è t r e (fig . 5). L a f ig u re 6 i l l u s t r e l a p r é s e n c e de deux fu ite s d a n s un tro n ç o n é tu d ié .

2. D ÉTER M IN A TIO N DE LA CIRC U LA TIO N DES EA UX SOUTERRAINES

L ’é ta b l is s e m e n t d e s c a r a c té r i s t iq u e s h y d ro lo g iq u e s d e s b a s s in s a q u i- f è r e s s u p e r f ic ie ls ou s o u te r r a in s a f a i t l ’o b je t de n o m b re u se s é tu d es e t r e c h e r c h e s de la b o r a to i r e ou s u r le t e r r a i n . L ’é tu d e d e s eau x s o u te r r a in e s p r é s e n te beaucoup de d if f ic u lté s , d u es à la co m p lex ité du p ro b lèm e ( l ’écoule m e n t d e l ’ea u à t r a v e r s d e s m il ie u x p o re u x s o u te r r a in s , d e s t r u c t u r e e t de te x tu re peu connues; l ’o b se rv a tio n d ire c te d iffic ile à r é a l is e r ; le choix d e s m é th o d es ne m od ifian t p a s le phénom ène é tud ié e tc . ).

T o u te fo is , g r â c e à l a c o l la b o ra t io n e n t r e g é o lo g u e s , h y d ro lo g u e s e t p h y s ic ie n s , on e s t a r r iv é à t r o u v e r d e s p ro c é d é s qu i p e rm e tte n t , dans une c e r ta in e m e s u re su iv an t le s c a s , la d é te rm in a tio n d es p a ra m è tre s de l ’écoule m e n t d es eaux s o u te r r a in e s .

L e t r a v a i l q u e n o u s p ré s e n to n s a é té a c c o m p li d a n s l ’in te n tio n de d é t e r m i n e r l a d i r e c t io n e t l a v i t e s s e d ’é c o u le m e n t d e s ea u x s o u te r r a in e s à t r a v e r s u n e é p a is s e co u ch e de s a b le r ic h e en s u b s ta n c e s o rg a n iq u e s e t en s e l s m in é ra u x , s i tu é e s u r le l i t t o r a l d e l a M e r N o ire , e n t r e M a m a ia -S a t e t N â v o d a r i .

Figure 4.

Schéma du circuit électronique du détecteur.

Na COM

ME

TRACEUR DANS

LES TRAVAUX

EDILITA

IRES 397


Figure S

Diagramme de l 'ac tiv ité le long de la conduite.

Figure 6

Diagramme de l'ac tiv ité le long de la conduite.

2 . 1 . L e s m é th o d e s a c tu e l le s d ’in v e s tig a tio n

P a r m i l e s m é th o d e s c la s s iq u e s u t i l i s é e s s u r une v a s te é c h e l le e t dont le s r é s u l t a t s so n t a s s e z s a t i s f a i s a n ts , no u s r e m a rq u o n s d ’a b o rd c e l le s qu i son t b a s é e s s u r l ’em p lo i d es t r a c e u r s . L e s t r a c e u r s c la s s iq u e s peuvent ê t re c l a s s é s se lo n le s m é th o d e s u t i l i s é e s p o u r le s d é te c te r . C es m é th o d es co m p ren n e n t d es d é te rm in a tio n s ch im iq u es, d es m e s u re s de r é s is t iv i té , l ' ap p lic a tio n de l a c o lo r im é t r ie , d e s m e s u r e s fo n d é e s s u r l 'e m p lo i de s p e c t r o - m è t r e s d e m a s s e e tc .

On u t i l i s e f ré q u e m m e n t c o m m e t r a c e u r l e c h lo ru r e d e so d iu m . I l e s t d é te c té p a r v o ie c h im iq u e , ou p lu tô t p a r la m é th o d e é le c t r iq u e . M a is la , m éthode ne peu t ê t r e em p loyée que pou r le s ro c h e s re la tiv e m e n t p e rm é a b le s e t p o u r d es d is ta n c e s de 7 à 15 m [1].

P u isq u e le s m ilie u x de fa ib le p e rm é a b il ité con tiennen t souvent une f r a c tio n im p o r ta n te d ’a rg i le , en y a jo u ta n t un é le c tro ly te q u i e n tra în e la coagu la tio n bü la d is p e r s io n d e s c o l lo ïd e s , on p ro v o q u e a in s i le c h a n g e m e n t de l a p e r m é a b i l i té . L e p ro c é d é n ’e s t p a s a p p l ic a b le d a n s le c a s d e c o u r te s d is ta n c e s , où le t r a c e u r p eu t in d u ire d e s c o u ra n ts de d e n s ité . L e c o lo ra n t le p lu s f ré q u e m m e n t u t i l i s é c o m m e t r a c e u r p o u r l ’é tu d e d e s e a u x s o u te r r a in e s e s t la f lu o re s c é in e . L a f lu o re s c é in e c o m m e rc ia le e s t fo r te m e n t s o lu b le d a n s l ’ ea u e t d a n s l e s so lu t io n s a lc a l in e s e t p e u t ê t r e d é te c té e d a n s d e s c o n c e n tra t io n s in f é r i e u r e s à 0, 00001% [1 ].

L a f lu o re s c é in e p eu t ê t r e u t i l is é e d an s le s t e r r a i n s qu i co n tien n en t d es c o u c h e s g r a n u lé e s ou f i s s u r é e s , m a is e l le n ’e s t d ’a u c u n e u t i l i t é d a n s le s s o ls o rg a n iq u e s ou a r g i l e u x don t l a p e r m é a b i l i t é e s t r e la t iv e m e n t f a ib le .

MNa COMME TRACEUR DANS LES TRAVAUX ÉDILITAIRES 399

E lle e s t a b so rb é e p a r le s ro c h e s a rg ile u s e s e t e lle p ré se n te une g ran d e a ff in ité d ’échange avec le s io n s d ’hyd rogène [2, 3, 4] .D’a u tre s c o lo ra n ts - t r a c e u r s so n t: l ’é o s in e , l e b le u d e m é th y lè n e , l a fu c h s in e , le ro u g e C ongo , le b i c h ro m a te de l i th iu m e tc . L e s t r a c e u r s c h im iq u e s le s p lu s u t i l i s é s so n t: le c h lo r u r e d e so d iu m , le b ro m o fo rm e , la d e x t ro s e e t m ê m e l e s d é te r g e n ts c o m m e rc ia u x . E n ce q u i c o n c e rn e le s t r a c e u r s p h y s iq u e s , n o to n s le s is o to p e s s ta b le s 2H e t 180. L e d e u té r iu m a é té u t i l i s é av e c s u c c è s d a n s n o tr e In s t i tu t p o u r le p ro b lè m e de l ’in te r f é r e n c e d e s n a p p e s d ’eau , q u i e n to u re n t l e s so n d e s p é t ro l i f è r e s . L a d é te c tio n se fa i t a is é m e n t p o u r d e s c o n c e n tra - , t io n s d oub les de l a c o n c e n tra tio n n a tu re l le . L ’u ti l is a t io n du t r a c e u r 180 e s t t r è s économ ique , l ’iso to p e é ta n t p r é s e n t d an s l a n a tu re .

A insi, on a c o n s ta té que l ’eau de la m e r co n tien t 180 dans une p lus g ran d e p ro p o rtio n que le s eaux d o u ces . N i 2H, ni I8O2, quoique t r è s ind iqués vu q u 'i l s n ’in te r a g i s s e n t p a s â v e c le so l, n 1 o n t é té u t i l i s é s d a n s n o t r e t r a v a i l à c a u se d e s m é th o d e s de d é te c tio n , p lu s d é l ic a te s e t s u s c e p tib le s d ’ê t r e e m p lo y é e s au la b o r a to i r e . L e s t r a c e u r s r a d io a c t i f s , u t i l i s é s t r è s so u v e n t e t t r è s e ff ic a c e m e n t c e s te m p s d e r n ie r s d an s l ’in d u s t r ie , l ’a g r ic u l tu r e , l ’in d u s tr ie du p é tro le , la b io lo g ie e t c . , s e so n t a u s s i im p o sé s d an s le dom aine de l ’é tude de l ’h y d ra u liq u e s o u te r r a in e .

L a m éth o d e d e s t r a c e u r s r a d io a c ti f s p ré s e n te , d an s ce c a s , l ’av an tag e d ’u n e t r è s g ra n d e s e n s ib i l i té e t d ’u n e d é te c tio n f a c i le , s a n s n é c e s s i t e r le p r é lè v e m e n t d ’é c h a n t i l lo n s . E n d e h o r s de c e la , l e s i s o to p e s r a d io a c t i f s p eu v en t ê t r e in c o rp o r é s d an s une g ra n d e v a r ié té de s u b s ta n c e s o rg a n iq u e s e t in o rg a n iq u e s , qu i co n s titu e n t un v a s te r é s e r v o i r pouvant nous fo u rn ir le s t r a c e u r s d o n t n o u s av o n s b e s o in . L a f o rm e c h im iq u e d e p r é s e n ta t io n d e s t r a c e u r s e s t e s s e n t ie l le p o u r é v i te r l e s phénom ènes de ré te n tio n p a r le so l.

2 . 2 . L e s c a r a c té r is t iq u e s du t r a c e u r id é a l

D ans l ’é tude de l ’é c o u le m en t d es eaux s o u te r r a in e s à t r a v e r s un m ilie u c a r a c t é r i s é p a r c e r t a in s p a r a m è t r e s , un t r a c e u r id é a l d o it s a t i s f a i r e l e s c o n d itio n s su iv a n te s :

a) L e s in te ra c t io n s p h y siq u e s e t c h im iq u e s de la su b s ta n c e ra d io a c tiv e co n ten a n t le t r a c e u r av e c l ’eau s o u te r r a in e , l e s m in é ra u x d e s ro c h e s t r a v e r s é e s , ou avec le s su b s ta n c e s o rg an iq u e s con tenues p a r le so l, ne doivent p a s m o d if ie r l ’é ta t in i t ia l du t r a c e u r .

b) L e s c h é m a de d é s in té g ra t io n dü t r a c e u r ra d io a c t i f d o it p e r m e t t r e u n e d é te c tio n f a c i le e t s im p le .

c) L a c o n c e n tra tio n n a tu re l le du t r a c e u r r e s p e c t i f d an s l ’eau s o u te r r a in e d o it ê t r e n é g lig e a b le p a r r a p p o r t à la c o n c e n tra t io n m e s u ra b le av ec l a m é th o d e c h o is ie .

d) L a su b s ta n c e ch im iq u e qu i co n tien t le t r a c e u r do it ê t r e so lub le dans l ’eau e t fo u rn ir une so lu tio n dont le s p a r a m è tr e s p h y s ic o -c h im iq u e s e t b io lo g iq u e s (v is c o s i té , pH , c o n te n u m ic r o - o r g a n iq u e e t c . ) l e s p lu s p r o c h e s p o s s ib le s de c e u x d e l ’e a u s o n t p h r é a t iq u e s .

e) L a co n ta m in a tio n de l ’eau s o u te r r a in e d o it r e s t e r d an s d e s l im ite s a u to r i s é e s e t c e la d an s un p é r im è t r e de p ro te c tio n s a n i ta i r e re la t iv e m e n t p e t i t .


f) L a p é r io d e ra d io a c tiv e d e s r a d io is o to p e s u t i l i s é s d o it ê t r e c o m p a r a b le à l a d u ré e d e l ’o u v ra g e .

g) L a p ro d u c tio n e t le p r ix d o iv en t ê t r e s a t i s f a i s a n ts .

2 . 3 . L a r é te n tio n p a r le s o l d e s t r a c e u r s r a d io a c t i f s

L e cho ix du t r a c e u r r a d io a c ti f e s t b ien f a i t lo r s q u e la p lu p a r t d e s co n d itio n s m e n tio n n é e s son t r e s p e c té e s . P o u r de n o m b reu x tra v a u x , ex é c u té s d a n s d e s c o n d itio n s s e m b la b le s , on a u t i l i s é d e s t r a c e u r s d if fé re n ts se lo n l e s c a r a c t é r i s t i q u e s d i f f é r e n te s d e s c o u c h e s a q u i f è r e s t r a v e r s é e s p a r le t r a c e u r .

L ’étude de la c a p ac ité de ré te n tio n d es ro c h e s t r a v e r s é e s e s t e s se n tie lle d an s le cho ix du t r a c e u r . C e tte ré te n tio n p ré s e n te deux a s p e c ts d if fé re n ts : l ’a d s o rp tio n e t l ’é c h a n g e io n iq u e . L ’é c h an g e io n iq u e r e t i e n t l e s t r a c e u r s d an s le so l, s u r to u t quand i l s se p ré s e n te n t so u s fo rm e de c a tio n s . L e s c a t io n s r a d io a c ti f s so n t re m p la c é s p a r le s c a tio n s n a tu re ls d es m in é ra u x a r g ile u x , p r é s e n t s d a n s l a m a jo r i té d e s t e r r a i n s . L ’in te n s i té d e l ’é c h a n g e ionique dépend de la p ré p a ra tio n e t du type du m in e ra i a rg ileu x p ré se n t dans le so l (é ta n t donnée le u r g ra n d e c a p a c ité de r é te n tio n le s a r g i l e s so n t e m p lo y ées d an s le t r a i te m e n t d e s eaux ra d io a c tiv e s ) . L a m e s u re dans la q u e lle un ion r e m p la c e un a u t r e d ép e n d de l e u r s c h a r g e s é le c t r iq u e s e t de l e u r s r a y o n s . C ’e s t a in s i qu e l e s a n io n s so n t r e te n u s p a r le s a r g i l e s d a n s u n e p e t ite m e s u re , ta n d is que le s c a tio n s le so n t am p le m e n t e t, p a rm i c e u x -c i, le s ca tio n s dont le rayon e s t le p lus p e tit, su b is sen t une p lus g rande ré ten tio n . P a r ex e m p le , d an s l ’échange d e s io n s d e s m é tau x a lc a lin s s u r d e s a r g i le s , l ’a f f in ité du p r o c e s s u s c r o î t du L i au C s . P o u r le s c a tio n s de ra y o n é g a l, le c a tio n dont la c h a rg e e s t la p lu s é le v é e e s t p lu s f a c ile m e n t re te n u . E ta n t donné qu e l ’é c h an g e io n iq u e a t te in t un é q u i l ib re d y n am iq u e , i l e s t é v id e n t q u ’on peut ré d u ir e la ré te n tio n des t r a c e u r s ra d io a c tifs , en a jou tan t du m a té r i e l in a c ti f , q u i p a r t ic ip e , lu i a u s s i , au p r o c e s s u s d ’é c h a n g e . E n d e h o r s d e c e la , s i la s o lu t io n - t r a c e u r e s t fo r te m e n t ac id e , la ré te n tio n s ’a ffa ib lit, p a rc e que le ca tio n H+ e s t p lu s fo r te m e n t re te n u que tou t a u t re ca tio n . (R éc ip ro q u e m e n t, s i l ’on u t i l i s e un e so lu tio n b a s iq u e , c ’e s t le c a tio n r a d io a c ti f q u i s e r a f a c ile m e n t r e te n u . )

L e s t r a c e u r s an io n iq u e s ou n o n io n iq u e s , t e l s qu e p a r e x e m p le l ’iode e t c e r ta in e s su b s ta n c e s o rg an iq u e s , son t su ffisam m en t in se n s ib le s à l'éch an g e ionique, m a is peuven t s u b ir une a d so rp tio n p hysique . T o u te fo is , en g én é ra l, l ’a d s o rp tio n p h y siq u e e s t m o in s im p o r ta n te que l ’échange ion ique . E v id e m m en t, p o u r v a in c re l ’ac tio n de ce s deux e ffe ts , on peu t in tro d u ire dans l 1 eau s o u te r r a in e u n e g ra n d e q u a n tité d e s u b s ta n c e in a c tiv e , m a is d a n s ce c a s , i l f a u t c r a in d r e l a f o rm a tio n d e s c o u r a n ts de d e n s i té p e r tu r b a t e u r s .

2 .4 . L e p r in c ip e d e l a m é th o d e

L a so lu tio n r a d io a c tiv e u t i l i s é e co m m e t r a c e u r e s t in tro d u ite d an s un p u its c e n tra l , la d é tec tio n s ’effec tu an t dans d ’a u t re s pu its e n v iro n n a n ts .C e s d e r n i e r s d o iv e n t ê t r e d is t a n ts d ’au m o in s 0 ,75 m du p u i ts c e n t r a l . U ne d is ta n c e p lu s p e t i te d o n n e ra i t d e s r é s u l t a t s fa u x à c a u s e d e s c o u r a n ts de d e n s i té . P o u r é v i t e r d ’a u t r e s e r r e u r s , u n e im p o r ta n c e p a r t i c u l i è r e d o it


ê t r e a c c o r d é e au v o lu m e du l i q u i d e - t r a c e u r e t à so n m o d e d ’in je c t io n (le pom page e s t exc lu ). D ans le s p u its e n v iro n n a n ts , on in tro d u it d es c o m p te u rs s u b m e rs ib le s co n n e c té s à une in s ta lla tio n de com ptage ou d ’e n re g is tre m e n t. L e p a s s a g e du l iq u id e r a d io a c t i f à t r a v e r s l ’un d e s p u its e n v iro n n a n ts e s t in d iq u é g r â c e à u n m a x im u m d e l a v i t e s s e d e c o m p ta g e . L a v a l e u r d e l a v i t e s s e d ’é c o u le m e n t d e s eaux s o u te r r a in e s e s t o b ten u e en d iv is a n t l a d i s ta n c e e n t r e l e s d eu x p u its p a r l e te m p s q u i s ’éc o u le e n t r e le m o m e n t de l ’in tro d u c tio n du t r a c e u r e t le te m p s d ’o b s e rv a tio n d ’un m a x im u m d a n s l a v i te s s e de c o m p ta g e .

S i l a d i r e c t io n d ’é c o u le m e n t n e c o n c o rd e a v e c a u c u n e d e s d i r e c t io n s p u i ts c e n t r a l - p u i ts e n v iro n n a n t, e l le p e u t ê t r e o b te n u e en m e s u r a n t l e s in te r v a l le s de te m p s n é c e s s a i r e s p o u r o b te n ir d e s a c t iv i té s m a x im a d an s l e s p u its e n t r e le s q u e ls p a s s e le t r a c e u r .

2 , 5 . R é a l is a t io n e x p é r im e n ta le

L e s m e s u re s ont é té e ffe c tu é e s à to u r de rô le d an s t r o i s e n d ro its d iffé r e n ts , s i tu é s le long du l i t to r a l , s u r l a p la g e , qu i a , d an s c e tte ré g io n , une la r g e u r d ’e n v iro n 200 m . D ’un e n d ro it à l ’a u t re , la d is ta n c e é ta i t d ’env iron 800 m . C haque fo is , on a c r e u s é 7 p u its (dont un p u its c e n tra l) , d ’une p ro fo n d e u r a p p ro x im a tiv e de 5 m , le s d is ta n c e s e n tre c e s p u its v a r ia n t de 1 m à 5 m . L e t e r r a i n é ta n t f r ia b le , d a n s ch a q u e e x c a v a tio n on a in tr o d u it un tuyau de f e r , ayan t 1 0 c m de d ia m è tre , e t d an s le q u e l on a p ra tiq u é de nom b r e u x tro u § la té r a u x , a f in q u e l ’e a u p u is s e c i r c u l e r e n to u te l i b e r t é .

L e t r a c e u r d e v a it s a t i s f a i r e au x c o n d itio n s s u iv a n te s :a) p é r io d e r a d io a c t iv e c o u r te , q u e lq u e s jo u r s to u t au p lu s ;b) é m is s io n y, f a c i le à d é t e c te r a v e c l ’a p p a r e i l l a g e d is p o n ib le ;c) f a ib le r é te n t io n p a r l e s o l .L e s deux p r e m iè r e s co n d itio n s é ta ie n t s a t i s f a i te s p a r le s ra d io iso to p e s

24Na, S2Br, 1311, e t M<>La.P o u r o b te n i r u n e r é te n t io n n é g l ig e a b le , l e s a n io n s 82gr , 1311 a u r a ie n t

é té le s p lu s in d iq u é s , m a is , co m m e à ce m o m e n t là i l n o u s fu t im p o s s ib le de nous en p r o c u r e r à b re f d é la i, nous nous so m m es co n ten té s d ’un m élange de NO3 140L a e t 24NaCl que le r é a c te u r IFA nous p ré p a re fa c ile m e n t.

C e tte so lu tio n , im p o sé e p a r l ’u rg e n c e , é ta i t d 'a i l l e u r s re n d u e a c c e p ta b le p a r l ’a b sen c e de m a té r ia u x a rg ile u x dans le so l é tud ié (le s ex p é rien c es o n t é té e f fe c tu é e s en t r o i s p o in ts d if fé r e n ts , e n t r o i s é ta p e s d is t in c te s , e t ch aq u e fo is d a n s un so l d é jà e x p lo ré dont nous c o n n a is s io n s la s t r u c tu r e e t la c o m p o s itio n ). P a r p ré c a u tio n , au su je t de l ’échange ion ique , nous avons a jo u té du N 0 3L a e t du N aC l in a c ti f s , dams un r a p p o r t 10 à 1 .

N ous d ev o n s m e n tio n n e r que , d a n s le c a s g é n é ra l , l e s m e i l le u r s t r a c e u r s so n t l e s a n io n s 82Br e t 1*Ц.

L a v a le u r d e l ’a c t iv i té n é c e s s a i r e a é té é v a lu é e to u t en te n a n t co m p te de l ’e ff ica c ité d ’e n re g is tre m e n t des co m p teu rs , de m êm e que d es d im ensions du t e r r a i n é tu d ié , d e l a v a le u r p r é s u m é e de l a v i t e s s e d ’é c o u le m e n t e t de l a ré te n t io n é v e n tu e lle du t r a c e u r p a r le s o l . L ’a c t iv i té to ta le n é c e s s a i r e p o u r u n e s e u le e x p é r ie n c e , fu t d ’e n v iro n 30 m e .

L a so lu tio n r a d io a c tiv e d e N O s ^ L a + ZfNaCl, d ’un v o lu m e de q u e lq u es l i t r e s , é ta i t le n te m e n t in tro d u ite d an s le p u its c e n tr a l , à une p ro fo n d e u r de


1 m s o u s la s u r f a c e de l ’ea u s o u te r r a in e . L a s o lu t io n é ta i t p r é p a r é e s u r p la c e , p a r la d is so lu tio n de la su b s ta n c e ra d io a c tiv e d an s de l ’eau e x t ra i te d ’une ex cav a tio n su ffisam m en t é lo ignée p o u r ne pas m o d if ie r le co u ran t sou te r r a in .

L ’in s ta lla tio n de d é tec tio n , t r a n s i s to r i s é e , é ta it co n s titu é e d ’un c irc u it in té g ra te u r avec e n re g is tre m e n t, d ’un c i rc u i t de com ptage , d ’une so u rc e HT e t de s ix c o m p te u rs G -M . L e s c o m p te u rs é ta ie n t in tro d u its d an s d e s tu b e s m é ta l l iq u e s é ta n c h e s . L ’é n e r g ie é le c t r iq u e é ta i t fo u rn ie p a r u n e b a t te r ie p o r ta b le d ’a c c u m u la te u r s de 12 V.

L e s m e s u re s e ffec tu ée s ont p rouvé que la d ire c tio n de l ’écou lem ent sou t e r r a i n é ta i t S u d -N o rd , a v e c un e v i t e s s e m o y e n n e de 0 ,6 m p a r jo u r . C e r é s u lta t , v ie n t d ’in f i r m e r une h y p o th èse a n té r ie u r e , co n c e rn a n t la po llu tion in d u s t r ie l le d ’un la c d ’eau douce, s itu é à p ro x im ité .

E n ce qui co n c e rn e la con tam in atio n te m p o ra ire de la nappe so u te rra in e , on s ’e s t p r é o c c u p é d ’é v i t e r to u t e f fe t n o c if en v u e de p o u v o ir u t i l i s e r le s ea u x s o u te r r a in e s . E n v é r i t é , p o u r q u e la c o n c e n tra t io n in i t ia l e en 140L a (5 m c/1) so it ré d u ite à la v a le u r to lé ra b le , un in te rv a lle de tem p s de 30 jo u rs e s t n é c e s s a i r e . P e n d a n t ce te m p s le liq u id e r a d io a c t i f p a r c o u r t à p e in e 18 à 20 m .P o u r l e 24Na la r é d u c t io n s e p r o d u i t p lu s r a p id e m e n t e n c o r e (7 jo u r s ) .

En conc lu sion , nous devons so u lig n e r qué la m éthode em ployée, quoique s im p le e t s û r e , p eu t e n c o re ê t r e p e rfe c tio n n é e p a r la m e s u re , en la b o r a to i r e , de la c a p a c ité de r é te n tio n d es ro c h e s é tu d ié e s p o u r d iv e rs t r a c e u r s e t en s a tu ra n t d ’a v a n c e c e t te c a p a c ité de r é te n tio n du t e r r a i n av e c du m a t é r i e l in a c tif . Il fau t d ir e e n c o re que l ’em plo i de p h o to m u ltip lica teu rs com m e d é te c te u r s p o u r r a i t r e n d r e p o s s ib le l a d é te c tio n d e s c o n c e n tra t io n s r a d io a c t iv e s t r è s p e t i te s , ce qu i p e r m e t t r a i t d 1 e m p lo y e r d e s a c t iv i té s to ta le s f a ib le s e t l 'o b s e r v a t i o n d e 1 'é c o u le m e n t s u r de g r a n d e s d i s t a n c e s .


[1] KAUFMAN. W.J. andORLOV, G. T . , J. Amer. Wat. Wks Ass. 48, 5 (1956) 559-572.[2 ] HA LEVY, E., NIR, A ., HARPAZ, Y . and MANDEL, S .. Atomic World 10. 5 (1959) 184-186.[3] HA LEVY, E ., Actes 2ème Conf. int. util. EAFP (ONU) 9 (1958) 56.[4 ] HALEVY, E ., NIR, A .. Proc. 2nd UN Int. Conf. PUAE 20 (1958) 162.[5 ] IW A 1, s. , GODA, T. and INOUE, Y . , Disposal of radioactive wastes, IAEA, Vienna, 2(1960) 435.[6] VERMEULEN, T . and H1ESTER, N. K . . Ind. Engng Chem. 44 (1952) 636.[7 ] AMPHLETT, C .B ., Research, Lond. 8. 9 (1955) 335-340.[8] ASTAPOV, C .B., EMELIANOV, V.S. and SBCOV, K. N ., Gidrotekhnika i melioratsiia 10, 2 (1959) 22-29.

D I S C U S S I O N

P .C . LEV EQ U E: D id you a tte m p t to d e te rm in e how m uch ac tiv ity w asre c o v e re d e i th e r by pum ping o r by so m e o th e r m ethod?

E . GASPAR: N o. T h e o p e ra tio n i t s e l f d id no t r e q u i r e any m e a s u r e m e n ts of t h i s s o r t , an d th e r e w as no h e a l th and s a fe ty p r o b le m in v o lv e d .

P . O ZEN D A : I n o tic e you m e n tio n th a t th e s a n d w as r i c h in o rg a n ics u b s ta n c e s . I t s e e m s to m e th a t th is f a c to r w ould be of c o n s id e ra b le im p o r ta n c e in th e io n ic f ix a tio n o f th e e le m e n ts . T h e a b s o rb e n t c o n s ti tu e n t


of th e s o il i s m a d e up no t s o le ly of c la y s but a ls o of h u m ic c o llo id s and o r g a n ic s u b s ta n c e s g e n e ra l ly . D o n 't you th in k th a t th is m ig h t h av e p la y e d a s ig n if ic a n t r o le in th e r e te n t io n o f th e t r a c e r ?

E . G A SPA R : C e r ta in ly . Y ou m u s t r e m e m b e r , h o w e v e r , th a t th eg ro u n d w a s r i c h in s a l t s , b e in g s a tu r a te d b y s e a - w a te r , so th a t w e w e re ab le to u s e th e Na24 in th e fo rm of Naz4C l. B e s id e s , th e a c tu a l p r o c e s s of r e te n t io n d id n o t a ffe c t th e o p e ra tio n in any w ay.

DETERMINATION OF THE DISTRIBUTION OF SEWAGE CONCENTRATION IN LARGE NATURAL WATERS

FROM PLANNED SEWAGE OUTLETS

O. BERG AND E. SOMER THE DANISH ISOTOPE CENTRE, COPENHAGEN, DENMARK


DETERMINATION OF THE DISTRIBUTION OF SEWAGE CONCENTRATION IN LARGE NATURAL WATERS FROM PLANNED SEWAGE OUTLETS. The use of short-lived radioisotopes like Br82 and Na24 for the tracing of water-flow in large natural waters is already well-established in many countries. The usual technique consists principally in a short-term in jection of a rad ioactive solution a t points of in terest, and subsequent charting of the distribution of the a c tiv ity a t d ifferen t tim e intervals a fter the in jec tio n . In this m anner q u a lita tive inform ation about flow patterns, e tc . can be obtained.

The authors study the problem of determ ining suitable p laces for sew age-w ater outlets in the open sea a t lo ca litie s where the problem of the pollu tion of bathing beaches, fishing waters, e tc . exists. S ince the d ifficu lty here consists in evaluating the concentrations of sew age-w ater a t d ifferen t points to be expected as a result of accum ulation over a long period, the application of the ordinary short-term injection principle m entioned before seem s unsatisfactory. However, they m odified the evaluation of m easurem ents, working on the assumption that a continuous injection is built up of an infinite number of identical short-term injections. The consequence of this .assumption is that sufficient knowledge of the distribution of the activity from a single short-term in jection a t different periods a lte r in jection m akes.it possible, by integration of activ ity concentration with regard to tim e at every point of interest, to construct a single chart showing the stationary d istribution of sewage concentration which would be obtained as a result of a continuous sewage outle t with known rate of flow.

Errors and lim itations of the m ethod, which can usually be overcom e under p rac tic a l conditions, are described.

The method has found widespread use in Denmark, and investigations are now carried out on a routine basis with instruments tha t can be handled by a single sem i-sk illed techn ician . The boat which tows the d e tector in a zigzag line through the area of interest is fitted with a Decca radionavigation instrument, a battery- driven transistorized logarithm ic ra tem eter and a clock. Sim ultaneous readings of activ ity , position and tim e are taken every 20 s by means of an autom atic 16-m m film cam era. The system is so sim ple that one day ’s m easurem ents can be p lo tted and evaluated before the nex t day ’s m easurem ents are started .

DETERMINATION DE LA DISTRIBUTION DES CONCENTRATIONS D'EAUX USEES, DANS LES GRANDES ÉTENDUES D’ÉAU NATURELLE, A PARTIR DE CERTAINS ORIFICES D’ÉVACUATION. Dès à présent, beaucoup de pays u tilisent couram m ent les radioisotopes de courte période, tels que le brom e-82 e t le sodium -24, pour étudier ré co u lem en t dans les grandes étendues d ’eau naturelle . La technique hab ituelle consiste princ ipa le ment à injecter, pendant un temps très réduit, une solution radioactive en des points choisis e t à étudier'ensuite la distribution de l 'a c t iv i té a divers in tervalles après l ’in jec tion . On peut ainsi obtenir des renseignem ents qualita tifs sur les m odes d ’écou lem en t, e tc .

Les auteurs é tud ien t la question du choix de lieux appropriés pour l ’évacuation d ’eaux usées en hau te m er, dans les localités où la pollution des eaux pose certains problèmes (plages, pêcheries, e tc . ). La d iff icu lté consistant en l ’occurrence à évaluer les concentrations d 'eaux usées auxquelles on peut s’a ttendre en divers points à la suite d ’une accum ulation prolongée, l 'ap p lica tio n du principe susmentionné de l ’in jection rapide ne sem ble pas satisfaisante. Les auteurs ont cependant m odifié le mode d 'év a lu a tio n des mesures en partant de l ’hypothèse qu'une in jection continue est constituée par un nombre infini d ’injections brèves id en tiques. Grace à ce tte hypothèse, si l ’on est suffisam m ent renseigné sur la distribution de l ’ac tiv ité résultant d ’uné seule in jection , à divers moments après cette in jection on pourra, en intégrant en fonction du temps les concentrations d ’activ ité relevées pour chacun des points étudiés, é tab lir un diagram m e unique indiquant la distribution stationnaire des concentrations d ’eaux usées, que l 'o n obtiendrait pour une évacuation continue d 'eaux selon un débit connu.

405

406 О. BERG and E. SOMER

Les auteurs exposent les erreurs e t les lim itations inhérentes à ce tte m éthode, difficultés que Гоп peut cependant, en règle générale, surmonter dans la pratique.

La m éthode a trouvé une large application au Danemark, où l*on poursuit actuellem ent les recherches de façon courante, à l*aide d*un appareillage qui peu t ê tre m anipulé par un seul tech n ic ien sem i-q u a lifié . L’em barcation qui remorque le detecteur en zigzag a travers la zone étudiée est munie d*un appareil de radionavigation Decca, d 'un intensim ètre logarithmique à transistors actionné par une p ile , ainsi que d*une horloge. Toutes les vingt secondes, l ’activ ité , la position e t le temps sont relevés au moyen d*une cam era autom atique de 16 mm. Le système est te llem ent simple q u 'il perm et de m ettre en graphiques e t d 'évaluer les mesures d*une joum ee avant de com m ercer les opérations de la journée suivante.

ОПРЕДЕЛЕНИЕ РАСПРЕДЕЛЕНИЯ КОНЦЕНТРАЦИИ СТОЧНЫХ ВОД В РЕЗУЛЬТАТЕ ПРОЕКТИРУЕМЫХ СБРОСОВ СТОЧНЫХ ВОД в БОЛЬШИЕ ЕСТЕСТВЕННЫЕ ВОДОЕМЫ. Во многих странах уже достаточно широко используются такие короткохивуцие радиоизотопы, как Вгвг и Na24,для мечения водных потоков в больших естественных водоемах. Обычные методы включают введение растворов короткоживущих радиоизотопов в еду на исследуемых участках и последующее составление диаграмм распределения активности через различные промежутки времени после введения. Таким путем может быть получена количественная информация относительно образцов потока и других вопросов.

В докладе рассматривается проблема определения подходящих мест для сбросов сточных вод в открытое море, исключающих возможность загрязнение пляжей, участков для рыбной ловли и т.д. Поскольку здесь имеется трудность определения концентрации сточных вод, накапливавшихся длительное время ка различных участках, применение обычного принципа кратковременного введения, о котором упоминалось прежде, представляется неудовлетворительным. Однако мы видоизменили метод оценки измерений, исходя из того, что постоянное введение состоит из неопределенного количества абсолютно одинаковых кратковременных введений. Следствием такого предположения является то, что достаточные знания о распределении активности после разового кратковременного введения в различные промежутки времени после введения дают возможность» посредством интеграции концентраций активности относительно времени на каждой представляющей интерес стадии, начертить единую диаграмму, отражающую постоянное распределение концентрации сточных вод в результате продолжительного сброса при известной скорости потока.

В докладе описываются ошибки и ограничения метода, которых в практических условиях, как правило, можно избежать.

Метод нашел широкое применение в Дании, и в настоящее время проводятся исследования в обычных условиях с использованием аппаратуры, которой может управлять один техник, не имепций большой квалификации. Судно, которое тащит детектор, двигаясь зигзагами через обследуемый район, снабжено радионавигационной аппаратурой Декка, батарейным транзисторным логарифмическим интенсиметром и часовым механизмом. Каждые две секунды производится одновременная регистрация активности, местонахождения и времени с помощью автоматической 16 мм кинокамеры. Система настолько проста, что результаты однодневных измерений могут быть вычерчены и подсчитаны до начала следующего рабочего дня.

DETERMINACIÓN DE LA DISTRIBUCION DE LAS CONCENTRACIONES DE AGUAS RESIDUALES, PROCEDENTES DE ALCANTARILLAS, EN GRANDES VOLUMENES DE AGUA NATURAL. En muchos países, radioisótopos de período corto, com o e l 82Br y e l 24Na, se vienen em pleando desde hace mucho tiem po para estud iar las corrientes reinantes en grandes volúm enes de agua natural. La técn ica corriente suele consistir sobre todo en inyectar una solución radiactiva de período corto en los puntos de interés y trazar a continuación un gráfico de la distribución de la activ idad a d iferentes intervalos de tiem po después de la ap licac ión . De esta m anera , pueden obtenerse datos cualitativos sobre la distribución de las corrientes.

La presente m em oria tra ta’ d e l problem a que p lan tea la e lecc ió n de lugares adecuados para evacuar m ediante tuberías las aguas servidas en e l m ar, en localidades en las que existe e l peligro de contam inación de las playas, zonas pesqueras, e tc . Dado que en este caso la d ificu ltad estriba en evaluar la concentración probable de aguas residuales, en diferentes lugares, com o resultado de la acum ulación prolongada, la a p licación de ios radioisótopos de periodo corto, que se ha mencionado más arriba, podría parecer poco satisfactoria. Sin em bargo, los autores han m odificado e l procedim iento de evaluación de las mediciones, partiendo de la hipótesis de que un núm ero infinito de inyecciones breves idénticas equivalea una inyección continua. De e llo se deduce que, si se conoce con precisión suficiente la distribución de la actividad resultante de una

DETERMINATION OF DISTRIBUTION OF SEWAGE CONCENTRATION 407

sola inyección, a distintos tiem pos después de esa inyección, se puede, integrando la concentración de a c t ividad en fuAción d e l tiem po en todos los pumos de interés, traza r un gráfico que indique la distribución estacionaria de la concentración de las aguas residuales, que se obtendría en e l caso de una evacuación continua a razón de un caudal conocido.

En la m em oria se describen los errores y las lim itaciones inherentes a este m étodo; sin em bargo, en la prác tica es posible superar las d ificultades m encionadas. Este m étodo se ha aplicado en gran escala en D inam arca y actualm ente se están llevando a cabo investigaciones con instrumentos que puede m anejar un solo operario sem iespecializado. En la em barcación que arrastra e l detector en z ig -zag en la zona objeto de estudio, se ha instalado un instrum ento de radionavegación D ecca, un integrador logarítm ico transistorizado alim entado por baterías, y un reloj. Por medio de una filmadora autom ática de 16 m m , se procede cada 20 s a un registro sim ultáneo de la actividad, posición y tiempo. Gracias a la sencillez del sistema, las mediciones efectuadas cada d ía se pueden representar g ráficam en te y evaluar antes de com enzar las d e l d ía siguiente.

1. INTROD U CTIO N

T h e p o llu tio n o f b a th in g b e a c h e s , f ish in g h a r b o u r s and f ish in g w a te r s w ith sew ag e w a te r and w a s te w a te r f ro m in d u s t r ia l o r a to m ic in s ta l la t io n s is to d a y a p ro b le m in m an y c o u n tr ie s a l l o v e r th e w o rld .

N ew p u r i f ic a t io n p la n ts and b e t te r o u tle ts of w a s te and se w a g e w a te r a r e being c o n s tru c te d ev e ry w h e re . T h e re a r e m any th in g s to tak e in to cons id e ra t io n in su c h p r o je c ts , but fo re m o s t one m u s t m ake s u r e th a t th e p r o p o se d a r ra n g e m e n t w ill no t g ive m o re th a n a to le r a b le w a s te -w a te r co n cen t r a t io n a t a l l c r i t i c a l lo c a tio n s . T h is h as to be so lv e d by su f f ic ie n t p u r i f i c a tio n and C are fu l p la c in g of th e d is c h a rg e o u tle t.

In o r d e r to 'd e c id e on th is , th e d ilu tio n th a t th e d isc h a rg e d w a te r u n d e rg o e s on i t s w ay f ro m th e o u tle t to th e c r i t i c a l lo c a t io n s m u s t b e know n.

U n til r e c e n t ly th e r e h a s b ee n no q u a n tita tiv e m e th o d to d e te rm in e th e d ilu tio n f ro m p la n n e d o u tle ts w h ich a r e no t y e t in e x is te n c e .

Study of th e m o vem en t of d y es tu ffs and f lo a ts can g ive a g e n e ra l id e a of th e d ire c tio n and v e lo c ity of w a te r flow . H ow ever, e r r a t i c r e s u l t s a re often ob ta in ed b ec au se f lo a ts a r e in fluenced not only by th e w a te r c u r re n t but a lso by th e w ind, and d y e s tu ffs a r e on ly s e e n in th e top la y e r s of w a te r , so th a t th e y do n o t g iv e p r o p e r in fo rm a tio n o f th e m o v e m e n t o f th e to ta l body o f w a te r .

T h e u s e of s h o r t - l iv e d r a d io is o to p e s l ik e B r 82and N a24 fo r t r a c in g th e w a te r flow in la rg e n a tu ra l w a te rs is a lre a d y w e ll-e s ta b lish e d in m any count r i e s [ Í - 6J . T h e u su a l te ch n iq u e c o n s is ts p r in c ip a lly in a s h o r t - t im e in je c tio n of a ra d io a c tiv e so lu tio n a t p o in ts of in te r e s t , and su b se q u e n t c h a r tin g of th e d is tr ib u tio n of the a c tiv ity at d iffe ren t tim e in te rv a ls a f te r the in jection . B u t h e re a lso only q u a lita tiv e in fo rm a tio n abqut th e flow p a t te rn is ob ta ined .

T h is p a p e r d e s c r ib e s a m ethod fo r fu r th e r t r e a tm e n t of th e in fo rm a tio n ob ta ined in ra d io iso to p e flow te s t s in o rd e r to g ive th e re q u ir e d q u an tita tiv e f ig u re s of th e d is t r ib u t io n of se w a g e c o n c e n tra tio n . In fo rm a tio n i s a ls o g iven on th e equ ipm en t u se d in D en m ark fo r th e s e te s t s , w hich a re now p e r fo rm e d ro u tin e ly by s e m i- s k il le d te c h n ic ia n s .

2. THEORY

T o u n d e rs ta n d o u r m ethod of ev a lu a tio n le t u s c o n s id e r w hat h appens at a w a te r o u tle t w ith a con tinuous d is c h a rg e of Q m 3/ s and a c o n c e n tra tio n of po llu tion C q (given fo r exam ple as th e nu m b er of co li b a c ill i p e r cubic m e te r ) .


Co Q co li a r e em erg in g p e r second from the ou tle t. As soon as the po llu t io n h a s le f t th e o u tle t a lo n g itu d in a l and t r a n s v e r s a l d if fu s io n w ill s t a r t . T h e t r a n s v e r s a l d if fu s io n le a d s to a d ilu tio n of th e co n tin u o u s flow , w hile th e lo n g itu d in a l d iffu s ion only- r e s u l t s in m a te r ia l com ing to a c e r ta in po in t В a f te r d if fe re n t m ig ra tio n tim e s .

T h e d ilu tio n and m ig ra tio n t im e d is t r ib u t io n e x p r e s s e d a s th e f ra c t io n of the p o llu tion a r r iv in g in a un it of vo lum e at po in t В w ith a m ig ra tio n tim e t is a function f(t)B of t .

T h e to ta l c o n c e n t r a t io n of, f o r e x a m p le , c o l i b a c i l l i a t В w ill b e

CO

с в = c o Q J f ( t)B dt c o l i / m 3 (1 )о

T o m ak e th e e x p re s s io n independen t of th e p o llu ting agen t, we find th a tth e c o n c e n tra tio n of p o llu tio n a t В r e la t iv e to th e c o n c e n tra tio n a t th e ou tle tis - '

o 00RB = - ÿ = Q J f(t)B dt . (2)

о

F o r th e p ro p e r p lann ing of th e w a s te -w a te r d isp o sa l sy s te m it is n e c e s s a r y to know Rb fo r a ll c r i t ic a l po in ts in the whole a re a in to which the w aste w a te r is d isc h a rg e d .

S u p p o sin g th a t a s h o r t - t im e in je c t io n of a r a d io a c t iv e so lu t io n a t th e o u tle t h a s ta k e n p la c e , th e c o u n t - r a te a t p o in t В w ill be a fu n c tio n o f th e t im e a f te r in je c t io n (m ig ra tio n t im e )

F ( t)B = к f (t)B cps . (3)

T h e c o n s ta n t к d epends on th e s e n s it iv i ty of th e d e te c to r S (c p s /c m 3) and on th e am ount of a c tiv ity u se d A (c)

к = A S coun ts mà/ s . (4)

N ow, u s in g E q s . 2, 3 and 4, we c a n d e te rm in e th e R b v a lu e fo r a c o n tin u o u s d is c h a rg e of Q m 3/ s f ro m o u r m e a s u re m e n ts a f te r a ra p id in je c tio n of A c.

00

Rb = Á f F{t)B dt- (5)о

T h e in te g ra l is th e a r e a u n d e r th e c u rv e show ing th e v a r ia tio n of count- r a t e a t В w ith t im e and S i s d e te rm in e d by c a lib ra t io n of th e d e te c to r in a l a r g e v o lu m e c o n ta in in g a s o lu t io n o f th e r a d io is o to p e in q u e s tio n w ith a know n s p e c if ic a c t iv i ty .

DETERMINATION OF DISTRIBUTION ,OF SEWAGE CONCENTRATION 409

W e ca n c h e ck th e c o r r e c tn e s s o f E q . 5 by apply ing th e " to ta l count" m e th o d fo r f lo w -ra te d e te rm in a tio n s d e s c r ib e d by HULL [7].

A cco rd in g to th is m ethod th e to ta l n u m b e r of coun ts N re c o rd e d f ro m a d e te c to r in a flow s y s te m w ith a flow Q a f te r in je c tio n of A c is

N = c o u n ts , (6)

w h e re S i s th e s a m e c a l ib ra t io n f a c to r a s in E q . 4.If we app ly E q s .5 and 6 to th e s itu a tio n d ir e c tly a t th e o u tle t w here Rg = 1

and N i s equal to th e in te g ra l , we s e e th a t

R outlet 1 a s X Q ‘ ’ ‘

F ro m E q s .5 and 6 i t ca n b e s e e n th a t Rb c a n a c tu a lly b e g iv en d i r e c t ly in t e r m s of " to ta l coun t"

Г Nr = _ 5 = _ S ( 7 )

R b c 0 N0

w h ereco

Nb = J F (t)e d t co u n ts .0

So f a r we h av e su p p o se d th a t th e in je c tio n o f th e t r a c e r ta k e s p la c e in an e x is tin g o u tle t w ith flow Q. H ow ever, a s th e flow Q is g en e ra lly so sm a llth a t i t d o es no t a ffec t th e flow p a t te r n in th e s e a , we ca n eq u a lly w ell app lyE q . 5 fo r th e s itü a tio n a t a n o t y e t e x is tin g w a s te -w a te r o u tle t to be lo c a te d a t th e p o in t w h ere o u r in je c tio n ta k e s p la c e , and w h e re Q i s th e e s tim a te d f lo w -ra te f ro m th e p la n n ed o u tle t.

3 . LIM ITATIONS

T h e r e a r e t h r e e a s s u m p tio n s th a t a r e r e q u i r e d to b e fu lf i l le d i f th e ap p lica tio n of th e m ethod is to g ive a r e l ia b le r e p r e s e n ta t io n of th e expected c o n c e n tra tio n of p o llu tio n a t a c e r ta in point:

1. T h e flow of th e p lanned o u tle t m u s t not be so g re a t as to a p p re c ia b ly in flu e n ce th e c u r r e n ts in th e r e c ip ie n t . T h e a s su m p tio n i s a n a tu ra l r e s u l t o f c a r r y in g ou t th e in v e s tig a tio n b e fo re th e a c tu a l e x is te n c e o f th e o u tle t.

2. T h e in te g ra tio n of c o u n t - r a te on ly g iv e s q u ite c o r r e c t r e s u l t s w hen th e c u r r e n t a t e v e ry p o in t h a s had a c o n s ta n t f lo w -ra te and d ir e c tio n d u rin g th e in v e s tig a tio n .

3. The th eory a s su m e s , a s shown in the p rev io u s sectio n , that the integ ra tio n s a re c a rr ie d out over an in finitely long tim e. H owever, it i s d ifficult to extend m e a su re m e n ts o v er m o re them one o r a few d a y s . One can conclude that the con cen tration s a re only determ ined c o rre c tly fo r points where the follow ing i s v a lid :


т »J F (t) dt = J F (t) dt ,

0 о

w h ere T is th e toteil m e a su r in g tim e .In o th e r w o rd s , i t is only p o s s ib le to d e te rm in e th e c o r r e c t d is tr ib u tio n

o f c o n c e n tra tio n s of sew age w a te r in a r e a s th ro u g h w hich a ll th e ra d io a c tiv e t r a c e r h a s p a s s e d a f te r th e tim e T .

T h e s e a s su m p tio n s g e n e ra lly do not re d u c e th e ap p lic a b ility of th e m e thod fo r th e in v e s tig a tio n Of p lanned w a s te -w a te r o u tle ts . In th is connection a t te n tio n shou ld b e d raw n to th e fa c t th a t th e r e q u ir e m e n ts on a c c u ra c y fo r th e s e d e te rm in a tio n s shou ld not be e x a g g e ra te d . O th e r f a c to r s of d e c is iv e s ig n if ic a n c e fo r th e u ltim a te p o llu tio n , su c h a s th e flo w -ra te of th e p lanned o u tle t and th e co n ten t of c o li b a c i l l i , a r e in m o s t c a s e s e s t im a te d w ith co n s id e ra b le u n c e r ta in ty .

4 . T H E M ETHOD IN USE

T h e ra d io a c tiv e t r a c e r u sed in o u r ex p e rim en ts is b ro m in e -82 as am m on iu m b ro m id e . T h e n e u tro n ir ra d ia t io n of th is m a te r ia l ta k e s p la c e at R isfí in th e D R -2 r e a c to r of th e D an ish A tom ic E n e rg y C o m m iss io n . T h e fine ly - d iv ided m a te r ia l i s se a le d in bags of po lyv iny lalcohol — a w a te r-so lu b le p la s t i c m a te r ia l . T h e s e b ag s a r e p u t in to s ta n d a rd i r r a d ia t io n c a n s . In m o s t c a s e s about 800 m e a r e u se d fo r th e e x p e r im e n ts . A fte r ir ra d ia tio n the can i s tr a n s p o r te d to the te s t s i te and th e bag is put in to a bo ttle contain ing about0. 5 1 w a te r . A fte r a p p ro x im a te ly 15 m in th e bag and i t s c o n ten t a r e fu lly d is s o lv e d . . .

B y m e a n s of a s im p le re m o te -h a n d lin g d e v ic e th e c o n te n t of th e b o ttle i s p o u re d in to th e s e a a t th e lo c a tio n to be te s te d a s a p o in t fo r a p o s s ib le w a s t e - w a te r , o u t le t .

E a r l i e r a s p e c ia l , p n e u m a tic a lly -c o n tro lle d w a s te -w a te r o u tle t s im u la to r [6] w as u se d fo r th e in je c tio n s . H ow ever, a f te r s e v e r a l e x p e r im e n ts i t w as found th a t s im p ly p o u rin g out th e t r a c e r so lu tio n on th e w a te r su rfa c e g iv e s a good v e r t i c a l s p re a d of th e a c tiv ity a f te r a s h o r t t im e , p ro v id ed the so lu tio n h a s about th e s a m e d en s ity as the w a te r .

T h e r a d io a c tiv ity m e a s u re m e n ts ta k e p la c e f ro m a m o to r Boat th a t tow s ;a s c in ti l la t io n d e te c to r w ith a 3 in X3 i n p la s tic s c in t i l la to r . T he d e te c to r is sh o c k p ro o f m o u n te d in a w a te r - t ig h t , c y l in d r ic a l s t a i n l e s s - s t e e l h o u s in g . T h e s e n s itiv i ty S of ou r d e te c to r fo r B r 82 is 4. 107 c p s /c m3 w ith a background o f 3 cp s below 1 m w a te r .

-T h e boat re p e a te d ly ta k e s a zigzag c o u rse th ro u g h th e whole a re a covered by th e -ra d io a c tiv e so lu tion .

T h e in s t ru m e n ta t io n on b o a rd g iv e s a fu lly a u to m a tic r e g i s t r a t i o n of p o s it io n , t im e and c o u n t - r a te .

On an in s t ru m e n t b o a rd in th e v e s s e l a r e m oun ted a lo g a r i th m ic count- r a t e r i ie te r , a c lo c k , and p o in te r in s t ru m e n ts th a t g iv e th e p o s it io n of th e b o a t a c c o rd in g to th e D e c c a r a d io n a v ig a tio n s y s te m .

A 1 6 -m m f ilm c a m e r a a u to m a t ic a l ly ta k e s s in g le p h o to g ra p h s of th e in s t ru m e n t b o a rd e v e r y 20 s .


T h e lo g a r i th m ic c o u n t - r a te m e te r d e s e r v e s s p e c ia l m e n tio n . D u rin g th e t e s t a w ide ra n g e of c o u n t-ra te s is r e c o rd e d . O nly a lo g a r i th m ic coun t- r a t e m e te r c a n m a k e r e c o r d in g s w ith s u f f ic ie n t r e l a t i v e a c c u r a c y o v e r a w ide ra n g e of c o u n t-ra te s w ithout m anual ad ju s tm e n ts of the in s tru m e n t s e n s itiv ity . O ur lo g a ri th m ic r a te -m e te r is a t r a n s is to r iz e d v e rs io n of the in s t ru m e n t d e s c r ib e d by CO O K E-Y A RBO R OU G H [8]. It c o v e r s th r e e d e c a d e s (1 - 1000 c p s ) .

5. PRO CESSING T H E DATA

T h e r e s u l t s of a day 's m e a s u re m e n ts a r e r e c o rd e d by th e above m ethod on a f i lm 's t r ip w ith up to tw o th o u sa n d s in g le p ic tu r e s . T h e f ilm i s d e v e loped and p la c e d in a f ilm r e a d e r . T h e p o s it io n and c o u n t-ra te i s r e a d p ic tu r e by p ic tu re and a f te r c o r re c tio n fo r decay and backg round p lo tted d ire c tly on a D e c c a m ap o v e r th e in v e s tig a tio n a r e a . W hen th e p lo tt in g of a z ig zag c o u rse th ro u g h th e ra d io a c tiv e a r e a is se e n to be com p le ted , the f i r s t "sn ap sh o t" of th e d is t r ib u t io n h a s b e e n p r e p a r e d and th e n e x t i s c o n tin u e d on a new m ap . T he p lo ttin g fo r ea ch in v e s tig a tio n day g iv e s 1 0 - 15 "sn a p sh o ts " w h ich c o r r e s p o n d to th e n u m b e r o f t im e s th a t th e a r e a h a s b e e n c o v e r e d d u r in g th e d ay .

I s o -a c t iv ity c u rv e s a r e th en p lo tted on each m ap in ac co rd an c e w ith the m a rk e d a c tiv ity v a lu e s .

T h e n ex t s te p r e q u i r e s th e d e te rm in a tio n of th e v a r ia t io n of c o u n t-ra te w ith t im e fo r a s m a n y p o in ts in th e a r e a a s a r e n e c e s s a r y fo r c h a r t in g th e expected d is tr ib u tio n of w a s te -w a te r co n c en tra tio n . T he d e te rm in a tio n cons i s t s o f m a rk in g e a c h of th e c h o se n p o in ts on a l l o f th e 10- 15 " s n a p s h o t0" and fo r each po in t to d e te rm in e ju s t a s m any m o m en ta ry va lues of th e count- r a te by in te rp o la tio n fro m th e iso -a c tiv i ty c u rv e s .

N ex t, a t im e - a c t iv i t y c o o rd in a te s y s te m i s d ra w n .fo r e a c h p o in t , in w h ich th e v a lu e s found above a r e p lo tte d . T h e s e v a lu e s c o r re s p o n d to th e F (t)g fu n c tio n . T h e a r e a u n d e r e a c h of th e c u r v e s i s d e te rm in e d an d th e e x p e c te d c o n c e n tra t io n of w a s te w a te r found f ro m E q . 5.

A ll c o n c e n tra t io n v a lu e s a r e p lo t te d on a m a p and i s o - c o n c e n t r a t io n c u r v e s a r e c o n s t ru c te d (F ig . 1).

A lthough th is d e s c r ip tio n sounds co m p lic a te d , th e w ork ca n be o rg a n iz e d in s u c h a m a n n e r th a t th e is o - c o n c e n t r a t io n m a p , w h ich i s th e f in a l r e s u l t o f one d a y 's m e a s u re m e n ts , c a n be r e a d y 8 - 10 h a f te r th e r e tu r n of th e b o a t . T w o o r t h r e e p e r s o n s p a r t i c ip a te in p r o c e s s in g th e r e s u l t s .

One m ap w ith is o -c o n c e n tra t io n c u rv e s , h o w ev e r, show s on ly th e d is t r ib u tio n of w a s te -w a te r c o n c e n tra tio n u n d e r th e sp e c if ic w e a th e r , t id e and c u r r e n t c o n d itio n s o f th e day o f in v e s tig a tio n . It i s o u r e x p e r ie n c e th a t a c e r t a in lo c a t io n c a n o n ly b e a p p ro v e d a s s u i ta b le f o r an o u tle t a f t e r 4 - 6 e x p e r im e n ts c o v e r in g s ta t i s t i c a l ly th e m o s t l ik e ly s i tu a t io n s . S o m e tim e s a lo c a tio n ca n be ru le d out a f te r one e x p e r im e n t, and i t is th e re fo r e im p o r ta n t to p r o c e s s th e d a ta fa s t so th a t fu r th e r u n n e c e s s a ry e x p e r im e n ts a t th is lo c a tio n can be avoided.


F ig .l

The curves show the concentration (%) of sewage water in sea-water calculated for 10 h continuous discharge of 1 m3 sewage water per

second from the point of injection.

6. FU TU RE D EV ELO PM EN TS

In 1962 a lone about 50 su c h e x p e r im e n ts w e re c a r r i e d out in D e n m a rk and m any a re p lanned fo r m u n ic ip a litie s and in d u s tr ia l e n te r p r i s e s . T h e re fo re , i t i s w o rth im p ro v in g th e m ethod f u r th e r . We a r e a im in g a t a b e t te r m a th e m a tic a l u n d e rs ta n d in g and tr e a tm e n t of o u r m e a su re m e n ts , so th a t we ca n apply th is m ethod even in c a s e s w h ere th e a fo re -m e n tio n e d assu m p tio n s a r e no t fu lfilled .

A n o th e r im p ro v e m e n t w ill be th e ch an g e o v e r to c o m p u te r te c h n iq u e s fo r th e p ro c e s s in g of m e a s u re m e n t d a ta . We a r e p lann ing the r e c o rd in g of a l l t im e , p o s i t io n and c o u n t - r a t e d a ta on p u n ch ta p e on b o a rd th e v e s s e l . Im m e d ia te ly a f te r r e tu r n to h a rb o u r th e d a ta w ill be tr a n s m itte d to th e GIER c o m p u te r of th e D an ish C o m p u te r C e n tre . T h e r e s u l t s g iven as iso -c o n c e n t r a t io n c u rv e s by an X -Y r e c o r d e r w ill be re a d y a few m in u te s la t e r . T h is m e th o d w ill a c h ie v e c o n s id e r a b le s a v in g in w o rk in g h o u r s and th e r e s u l t s w ill b e a v a ila b le e a r ly enough to allow th e nex t d a y 's ex p e rim en t to be p lanned m o re c a re fu lly .


T h e in te g r a t io n m e th o d i s th e r e s u l t of d is c u s s io n s w ith S ta te H y d ro - g r a p h e r F . H e rm a n n , T h e D a n is h I n s t i tu te fo r F i s h e r i e s and M a r in e R e s e a r c h . T h e lo g a r i th m ic c o u n t - r a te m e te r w as d ev e lo p e d by B . F . H e r tz


and th e a u to m a tic r e c o r d in g m e th o d by N . J . S tau n , b o th f ro m th e D a n is h Iso to p e C e n tr e .

R E F E R E N C E S

[1] THOMAS, H. A . , "Radioactive Isotopes as Tools in sanitary engineering Research",Proc. 1st Int.Conf. PUAE15 (1955) 42.

[2] COCHRANE, H. B. ,"The use of radioactive Isotopes and characteristic Bacteria in tracing sewage Pollution in the Sea", The Surveyor (21 April 1956) 173.

[3] ELY, R. L ., "Radioactive tracer Study of sewage Field in Santa Monica Bay, ” IRE Trans, on Nuclear Science (March 1957) 49.

[4] GOODMANN, E. L , "A radio T racer for studying sewage D istribution” , Ind. Eng. Chem . 50 (1958) 210.[5] 1JUNGGREEN, K. e t aL , "Tracing of water flow by means of radioactive Isotopes and scintillation Coun

ters", J. App. Radiat. and Isot. 5 (1959) 204.[6] ALLINGHAM, R. A. and SOMER, E . , "Instrum entation for full scale techn ical radioactive tracer Experi

m ents", Ingeniorea, Int. Ed. 4 -(i960) 91.[7] HULL, D. E. and MACOMBER, М ., "Flow M easurements by the to ta l-count Method", Proc. 2nd. Int. Conf.

PUAE 19 (1958) 324.[8] COOKE-YARBOROUGH, E.H . and PULSFORD, E. W ., "An accurate logarithm ic counting-rate Meter cover

ing a wide Range”, Proc. Inst. Elect. E ngg., Part II, 98 (1951) 196.

D I S C U S S I O N

R. W O LF: I w onder w h e th e r , in m any c a s e s , c h e m ic a l t r a c e r s w ould not be p e r fe c tly adequate fo r th e p u rp o se s you have in m ind . In F ra n c e , we u se rh o d am in e В to p ro v id e u s w ith in fo rm a tio n on su ita b le se w a g e -d isp o sa l s i t e s . O bviously th e p ro c e s s in g of sa m p le s g iv es r i s e to c e r ta in d ifficu ltie s b u t, on th e o th e r hand , th e r e a r e no sh ie ld in g p ro b le m s in co n n ec tio n w ith s to r a g e o r t r a n s p o r t . M o re o v e r , i t is e a s i e r to m o d ify t e s t p r o g ra m m e s w hen u s in g c h e m ic a l s u b s ta n c e s th a n i t i s w ith r a d io a c t iv e t r a c e r s .

I should a lso be in te re s te d to know w hether you p lan to adapt th is m ethod to s m a ll- s c a le m o d e ls . By u s in g th is techn ique it m ight be p o ss ib le to c a l i b r a te su c h m o d e ls f ro m th e p o in t of v iew of d iffu s io n and o th e r p h enom ena .

E . SOMER: We a r e in fac t p re p a r in g m odel e x p e r im e n ts , m a in ly to se e how th e m e th o d c a n be a p p lie d to c a s e s w h e re c o n d itio n s a r e n o t w h a t w e have so f a r a s su m e d th e m to be: A s fa r as ch e m ic a l t r a c e r s a re co n cern ed , tech n iq u es involving th e u se of dyes tu ffs fo r quan tita tive d ilu tion ex p e rim en ts a r e m u ch m o re c o m p lic a te d th a n o u r m eth o d b e c a u s e , in ad d itio n to ta k in g sa m p le s , one h as to m ake ind iv idual p h o to m e tric d e te rm in a tio n s . One d a y 's w o rk w ith o u r m e th o d p ro v id e s u s w ith about 2000 m e a s u re m e n ts , w hich is f a r m o re th a n w ould be p o s s ib le w ith d y e s tu ffs . O ur r e s u l t s a r e th e re fo r e bound to be m o re a c c u ra te .

F ro m the econom ic s tan d p o in t, i t would a lso be v e ry expensive to c a r ry out co lo u rin g -a g e n t o r c o li- b a c te r ia te s t s w h ere no ac tu a l o u tle ts ex is t. W ith o u r tech n iq u e , th e c o s t of one fu ll s e t of e x p e r im e n ts , i .e . 4 -6 s in g le e x p e r im e n ts , is eq u iv a len t in D en m a rk to th e p r ic e of 50 m of o u tle t p ipe . R hodam in e t e s t s would be fa r m o re ex p en siv e .

R . W O L F: Y e s , b u t s m a l l - s c a l e m o d e ls a r e b u ilt p r e c i s e l y b e c a u s e t e s t s in n a tu re a r e so ex p e n siv e w hen a good ap p ro x im a tio n to ac tu a l cond i

414 О. BERG and E. SÔMER

t io n s i s r e q u ir e d . O nce a s m a l l - s c a le m o d e l w ith rh o d a m in e is a v a ila b le , i t i s e x tre m e ly e a sy to re p e a t th e te s t s . I am r a th e r s u rp r is e d , by th e way, in v ie w of th e m a n y v a r ia b le s in v o lv e d , th a t 4 -6 t e s t s sh o u ld b e enough to en a b le you to e l ic i t a l l th e in fo rm a tio n you n ee d .

E . SOM ER: On th e s u b je c t of m o d e l e x p e r im e n ts g e n e ra l ly , I sh o u ld l ik e to s a y th e fo llo w in g . D e n m a rk i s q u ite a s m a ll c o u n try bu t th e r e a r e about 40 — 50 p la c e s w h ere we p la n to c a r r y out o u r te s t s . It would be u tte r ly im p o s s ib le — and I d o n 't r e a l ly th ink it is even n e c e s s a r y - to c a r r y out c o s tly m o d e l e x p e r im e n ts a t e a c h of th e s e s i t e s . W e f in d — and th i s i s a l s o th e v iew of our h y d rau lic s e x p e r ts — th a t th e in fo rm atio n provided by an av erag e of 4 -6 e x p e r im e n ts i s a d e q u a te f o r th e p u rp o s e o f s e le c t in g a s e w a g e -o u tle t lo c a tio n .

T h e re is a n o th e r po in t I shou ld l ik e to m a k e . As o u r m ethod is a quant i ta t iv e one and y ie ld s in fo rm a tio n on se w a g e -w a te r c o n c e n tra tio n s a t p a r t i c u la r s i t e s , i t is a lso u se fu l f ro m th e po in t of v iew of d e te rm in in g w hat p u r if ic a tio n e ff ic ie n c y i s r e q u ir e d a t th e p u r if ic a tio n p la n ts fee d in g th e sew ag e o u t le ts in o r d e r to p r e v e n t p o llu tin g a g e n ts f ro m e x c e e d in g p e r m i s s ib l e l im i t s a t th e c r i t i c a l lo c a l i t i e s .

MESURE DU POIDS SPÉCIFIQUE DE L'ÉMULSION (EAU - VAPEUR) S'ÉCOULANT DANS UN

TUBE-ÉCRAN DE CHAUDIÈRE INDUSTRIELLE: EMPLOI DE SODIUM-24

C . M AILLE E T J. M O IN AR D

SO C IÉ T É S T E IN e t ROU BAIX, PARIS

E T

D. B L A N C E T J. F O N T A N

F A C U L T É DES SC IE N C E S, TO U L O U SE , FRANCE


MEASUREMENT OF THE SPECIFIC GRAVITY OF THE WATER-STEAM EMULSION FLOWING IN A SCREEN TUBE OF AN INDUSTRIAL BOILER USINÇ SODIUM-24. The circulation inside an industrial boiler depends cm the ñ o w -ra te and on the specific gravity of the w ater-steam em ulsion. Conventional methods for m easuring flow -ra te in screen tubes require com plex dev ices and m ay disturb the phenom enon under study.

The employm ent of an external radioactive source and detector for densitometry measurements is sim ple and in com m on use. Unfortunately, it is d ifficult to use in the present case. The authors have therefore d e veloped a m ethod consisting of the introduction of a calcu la ted am ount of sodium -24 in to the bo ile r w ater. This very sim ple dev ice does not disturb the now .

The experim ental design, built up a t die test station of Stein and Roubaix C o . , is described. Sodium -24 gives consistent results, although less accurate than the densitom etric process using an external source o fC o6*. Investigations are now being m ade on a series o f p a ra lle l tubes with the geometry, used in industrial boilers.

MESURE DU POIDS SPÉCIFIQUE DE L'ÉMULSION (EAU - VAPEUR) S’ÉCOULANT DANS UN TUBE-ÉCRAN DE CHAUDIERE INDUSTRIELLE: EMPLOI DE SODIUM-24. La circulation à l'in térieu r d 'une chaudière industrie lle est conditionnée par la vitesse d 'éco u lem en t e t le poids spécifique, de l'ém ulsion (eau - vapeur). Les procédés classiques de m esure de la v itesse d 'é co u lem en t dans les tubes d 'écrans nécessiten t des m ontages d iffic iles e t risquent de perturber le phénom ène à m esurer.

L 'em ploi d 'une source radioactive externe est un procédé simple e t courant de densim étrie; i l est hélas d iffic ile à adapter dans le cas actuel. C 'est pourquoi les auteurs ont adopte une technique qui consiste â In troduire dans l 'ea u de la chaudière une quantité calculée de sodium-24. Ce procédé, très sim ple, ne perturbe pas l'écoulem ent.

Les auteurs décrivent le montage expérim ental réalisé à la station d'essais de la Société Stèin e t Roubaix. La m éthode du sodium -24 conduit à des résultats cohérents, bien que moins précis que le procédé densim é- trique em ployan t une source externe de MCo. Les études en cours concernent une série de tubes para llè les , disposés selon la géom étrie adoptée dans les chaudières industrielles.

ИЗМЕРЕНИЕ УДЕЛЬНОГО ВЕСА ЭМУЛЬСИИ (ВОДА - ПАР), ПРОТЕКАВШЕЙ В ЭКРАНИРУЮЩЕЙ ТРУБЕ ПРОМЫШЛЕН

НОГО КОТЛА С ПОМОЩЬЮ НАТРИЯ-24. Циркуляция внутри промышленного котла обусловлена скорости» потока и удельным весом эмульсии (вода - пар). Обычные методы измерения скорости потока в экрави~ рунщих трубах связаны с трудными монтажными работами, и существует опасность получения и осаженных результатов.

Использование внешнего радиоактивного источника, являвшееся простым и широко применяемым методом денсиметрии, в настоящем случае представляет, к сожалению, трудность. Вот почему аатори применили метод, который состоит в том, чтобы вводить в воду котла отсчитанное количество натрия- 24. Этот очень простой метод не препятствует потоку.

Авторы описывают экспериментальный монтах, проведенный на опытной станции общества Штейн и Рубеке. Применение натрия-24 приводит к согласованным результатам, хотя и менее точным, чем при денсиметрическом методе, когда используется внешний источник с Сов°. Приводящиеся исследования касаются серии параллельных труб, расположенных по геометрии, принятой в промышленных котлах.

415

416 C. MAILLE et al.

MEDICION CON AYUDA DE SODIO-24 DEL PESO ESPECÍFICO DE LA EMULSION (AGUA-VAPOR) QUE ATRAVIESA LA PARRILLA DE AGUA DE UNA CALDERA INDUSTRIAL. La circu lación en e l in terior de una caldera industrial és función de la velocidad de l flujo y del peso específico de la emulsión (agua - vapor). Los procedim ientos clásicos de m edición del flujo en las parrillas de agua requieren dispositivos com plejos que pueden llegar a perturbar e l fenóm eno que se desea medir.

El sim ple procedim iento de em plear una fuente rad iactiva externa, que se em plea con frecuencia en densim etría, resulta d ifíc il de u tiliza r en e l presente caso. Por este m otivo, los autores han recurrido a una técn ica que consiste en introducir en e l agua de la caldera una cantidad calculada de sodio-24. Este p rocedim iento , que es muy sencillo , no a ltera e l flujo.

Los autores describen e l dispositivo experim ental montado en la estación de ensayos de la Société Stein e t Roubaix. El m étodo d e l sodio-24 da resultados coherentes, aunque menos exactos que la densim etría por m edio de una fuente externa de 6DCo. Los estudios se rea lizan con una serie de tubos paralelos, dispuestos según la m ism a geom etría que en las calderas industriales.

1. IN TR O D U CTIO N

P o u r é tu d ie r e x p é r im e n ta le m e n t la c i rc u la t io n d an s un e c h a u d iè re , i l f a u t d é te r m in e r le s c a r a c t é r i s t i q u e s p h y s iq u e s p r in c ip a le s de l ’é m u ls io n qui son t le s su iv an te s : a) la p re s s io n èt la te m p é ra tu re , b) la v ite s se d’écoule m en t, c) le po ids spécifique .

L a d é te rm in a tio n de la te m p é r a tu re ou de la p re s s io n e s t a s s e z fa c ile , m a is iso lém e n t, c e s p a ra m è tre s donnent peu de ren se ig n em en ts . P a r con tre , l a c o n n a is sa n c e ,m ê m e is o lé e ,d e la v i te s s e d ’é c o u le m en t ou du po ids s p é c ifiq u e e s t un re n s e ig n e m e n t q u a lita tif t r è s in té r e s s a n t .

P lu s ie u r s é tu d e s im p o r ta n te s 11] ont eu p o u r o b je t la c i rc u la t io n n a tu r e l l e d an s l e s tu b e s de c h a u d iè re s e t ont p e r m is d ’é la b o r e r d e s m é th o d e s d e c a lc u ls u t i l i s é e s p o u r d é te r m in e r le s d im e n s io n s d e s c h a u d iè re s in d u s t r i e l l e s m o d e rn e s . L e s e x p é r im e n ta te u rs ont g én é ra le m en t m e su ré le s te m p é r a tu r e s , l e s p r e s s io n s e t l e s v i t e s s e s d ’é c o u le m e n t, p a r l e s m é th o d e s c la s s iq u e s . B ien so u v en t, p o u r d é te r m in e r le s a u t r e s p a r a m è t r e s p r in c i paux, i l s ont é té o b lig és de f a i r e le u r s e s s a is dans des conditions b ien d iffé r e n te s de c e lle s que l ’on re n c o n tre dans la p ra tiq u e .R é c e m m e n t,p lu s ie u rs a u t e u r s [2 ,3 ,4 ,5 ,6 ,7 ,8 ,9 ,1 0 ,1 1 ,1 2 ,1 3 ] ont u t i l is é la m éthode d 1 ab so rp tio n de ray o n s g am m a p o u r m e s u r e r le p o id s sp é c if iq u e de l ’é m u ls io n lo r s de le u r s e s s a is .

C e p en d a n t, to u s c e s t r a v a u x n e f o u rn is s e n t p a s l e s m o y e n s e x p é r i m e n tau x a p p l ic a b le s au x c h a u d iè re s en fo n ctio n n em en t in d u s t r ie l . E n effe t, l ’em p lo i d es d isp o s itif s c la s s iq u e s de m e su re de la v ite s se te ls que le s tubes de P ito t et le s o r if ic e s d é p rim o g èn es e s t t r è s l im ité p u isq u ’il n ’e s t p as p o ss ib le de le s in s ta l l e r s u r un n o m b re im p o rta n t de tu b es a in s i qu’il e s t exigé p o u r u n e t e l l e é tu d e , s a n s c r é e r u n e p e r tu r b a t io n im p o r ta n te de l ’é c o u le m e n t, ou e n c o re , r i s q u e r de g r a v e s e n n u is d ’e x p lo ita tio n p a r le n o m b re a c c r u d e v a n n e s e t d ’a p p a r e i l s . P a r a i l l e u r s , l a m é th o d e d e m e s u r e du po ids spéc ifique de l ’é m u lsio n p a r la m éthode d ’a b so rp tio n de ray o n s gam m a n é c e s s i te une s o u rc e e t un d é te c te u r . L ’un ou l ’a u t re de c e s d isp o s itif s e s t p la c é dans la c h a u d iè re , e t c e la re n d t r è s com pliquée l ’ap p lica tio n de la m é thode à une c h a u d iè re in d u s tr ie l le .

N ous av o n s donc u t i l i s é une no u v elle m éthode de m e s u re du po ids sp é cifique d 'u n e ém u lsio n , ap p licab le en un point quelconque d ’un tube et fa isa n t ap p e l se u le m e n t à un a p p a re il la g e de m e s u re e x te rn e aux tu b e s e t au fo y e r de la ch a u d iè re . P o u r l ’app lica tion de c e tte m éthode, un rad ioé lém en t in té g ré d a n s un c o m p o sé non v o la til , e s t d is s o u s d an s l ’eau de la c h a u d iè re . L o rs

MESURE DU POIDS SPÉCIFIQUE DE L’ÉMULSION (EAU-VAPEUR) 417

d e la fo rm a tio n de l a v a p e u r , l a q u a n tité de ra d io é lé m e n t d a n s 1*é m u ls io n d im in u e p u isq u e l a v a p e u r n ’e n t ra în e p ra tiq u e m e n t p a s de m a t iè r e s o lid e . A in s i, au m o y en d ’un d é te c te u r q u i m e s u r e l ’a c t iv i té de l ’ea u en b a s d ’un tube d ’é c ra n , p a r ex em p le , avan t v a p o r isa tio n , pu is en su ite en hau t du tube , l à où l ’é m u ls io n e s t fo rm é e , no u s pouvons c a lc u le r le p o id s sp é c if iq u e d e c e tte é m u ls io n . C e tte m éthode a d é jà é té em ployée p a r DENGLER [14] m a is avec une t r è s m a u v a ise p ré c is io n .

L e but d es e s s a is é ta i t de v é r i f ie r l ’e f f ic a c ité de c e tte m éth o d e d e m e s u re a f in de p o u v o ir l ’a p p liq u e r e n s u ite aux c h a u d iè re s in d u s t r ie l le s . P o u r c e la , n o u s a v o n s c o n s t r u i t u n e m a q u e tte de c h a u d iè re à c i r c u la t io n n a tu r e l l e e t nous av o n s m e s u r é le p o id s sp é c if iq u e de l ’é m u ls io n , d ’a b o rd p a r a b so rp tio n de ra y o n s gam m a, pu is p a r la nouvelle m éthode . T ous le s a u t re s p a r a m è t r e s é ta ie n t m e s u r é s a fin d e p e r m e t t r e d e s c o m p a ra is o n s av e c l e s t r a v a u x d ’a u t r e s e x p é r im e n ta te u rs .

2. D ESC R IPT IO N DE LA CHAUDIÈRE E X P E R IM E N T A L E

L a c h a u d iè re à c irc u la t io n n a tu re l le e s t c o n s ti tu é e p a r :a) un tu b e v e r t i c a l ф 60 X 70 m m de 6 m de lo n g u e u r, ch au ffé s u r une

d e m i-c irc o n fé re n c e se u lem en t, p a r sep t r é s is ta n c e s p laquées co n trela p a ro i e x té r ie u re s im u lan t un tube d ’é c ra n de ch au d iè re ,

b) un tube v e r t ic a l de r e to u r d ’eau (fig . 1 et 2).L a p re s s io n nom ina le de fonctionnem en t e s t de 6 k g /c m 2.C e tte p re s s io n e s t b a s se , co m p arée à c e lle d es c h a u d iè re s in d u s tr ie lle s

m o d e rn e s , m a is e l le p e rm e t une r é a l is a t io n a s s e z sim ple, e t peu o n é re u s e . L a v a p e u r f o rm é e d a n s l a c h a u d iè re e s t c o n d e n sé e d a n s un s e rp e n t in r e f ro id i à l ’eau e t le c o n d e n sâ t re to u rn e au b a llo n . L e c i r c u i t e s t donc co m p lè te m e n t f e rm é .

S u r le s c h é m a r e p r é s e n té à l a f ig u re 1, l e s s e n s de c i rc u la t io n d ’eau e t de v a p e u r so n t r e p r é s e n té s p a r d e s f lè c h e s e t l ’e m p la c e m e n t d e s ap p a r e i l s de m e s u re s e s t in d iq u é . L ’e n s e m b le e s t so ig n e u se m e n t c a lo r ifu g é e t le tube e x p é r im e n ta l e s t en to u ré de c o q u ille s en a m ia n te d ém o n tab les , p e r m e tta n t le dém ontage du tube et son rem p lace m e n t éven tue l p a r un a u tre tube de d ia m è tre ou de fo rm e d if fé re n ts .

L ’a d m is s io n de la so lu tio n co n ten a n t le c h lo ru r e de so d iu m a c tiv é e s t e ffec tu ée p a r le s a s p ré s e n ta n t to u te ? le s g a r a n t ie s de s é c u r i té . M a lg ré l a c o u r te p é r io d e du so d iu m (15 h) e t b ien que le s d o se s u t i l i s é e s so ie n t in fé r i e u r e s aux v a le u r s ’ l im i te s f ix é e s p a r la C o m m iss io n de p ro te c tio n r a d io lo g iq u e , un r é s e r v o i r e s t p la c é en f in de c i r c u i t p o u r c o n s e r v e r l e s ea u x u sé e s , fa ib lem en t ra d io a c tiv e s , p lu s ie u rs jo u rs avant de le s envoyer â l ’égout.

L e s d é b i ts d ’eau e t de v a p e u r so n t m e s u r é s au m oyen de d ia p h ra g m e s e t de m a n o m è tre s d if fé re n tie ls à tu b e s en U. L e d ia p h ra g m e de m e s u re du d é b it d ’eau e s t p la c é s u r le tu b e de d e s c e n te s o u s le b a llo n ta n d is q u e le d ia p h ra g m e de m e s u re du d éb it de v a le u r e s t p la c é s u r la tu y a u te r ie de d é g ag e m e n t de v a p e u r r e l ia n t le ba llo n au c o n d e n se u r. L a p r e s s io n au b a llo n e s t donnée p a r un m a n o m è tre du type B ourdon . L e s te m p é r a tu re s à chaque d ia p h ra g m e , à la s o r t ie du co n d en seu r e t dans chaque zone de m e s u re s , son t m e s u ré e s avec d es th e rm o c o u p le s p la c é s s u r l a ’p a ro i e x te rn e d es tu b e s . C es th e rm o c o u p le s donnent la te m p é r a tu re de s u r fa c e d e s tu b e s q u i e s t , p r a t i -

418 C . MAILLE et al.

Figure 1

Schéma de la chaudière expérimentale.

q u e m e n t, c e l le de l ’é m u ls io n a in s i q u ’i l a é té v é r i f ié à un e n d ro it av e c un th e rm o c o u p le té m o in p la c é d a n s un d o ig t d e g an t.

L a m e s u r e du p o id s sp é c if iq u e m o y en d e l ’é m u ls io n e s t f a i te su iv a n t l a te c h n iq u e d é c r i t e d a n s l e s p a r t i e s 3 . 2 e t 3 . 3.

3 . D ETER M IN A T IO N DU POIDS S P E C IF IQ U E DE L ’ÉM ULSION E A U -V A P E U R

3 .1 . D é fin it io n s

S o it un tu b e v e r t i c a l d an s le q u e l c i r c u le de b a s en h au t, une é m u ls io n d ’ea u e t d e v a p e u r , c o n s ti tu é e p a r de l ’ea u d a n s la q u e lle so n t n o y é e s d e s b u lle s de v a p e u r . C es b u lle s de vap eu r se dép lacen t à une v ite s se su p é rie u re à c e lle de l ’eau (fig . 3 e t 4). ^

MESURE DU POmS SPÉCIFIQUE DE L’ÉMULSION (EAU-VAPEUR) 419

Ш Ш Ё Ё ш ьк

W ÈÈÈÈIÈIIm s % ¡ ¡p f á

И в»W ÈlÈlllÊsÈÈIIIm

■и м ■ ■ ■

ЯР?

МИ

^ Н | ¡ J

■ ; v

■ и и и и

ШЯвятЩ Я Я

Ш и■H■ и м

Д И И И и м

¡ я ^ и

■ И¡ н мlllWlla

ЛшЙЙёИ И и ' И Ь . » — .■.•Щ Д Ш И И -:иИ У М И к ..МММИММЮИШж И И В ш м И И И »

Й Ш И И И И И МжМВИДИИМИИИИи ■ I

■

iS m S B

« ■ рт »

Figure 2

Vue d'ensem ble de la chaudière expérimentale.

P o u r une se c tio n S du tu b e , un e p a r t i e Se e s t o cc u p ée p a r l ’ea u ta n d is qu e l e r e s t e £* e s t o ccu p é p a r la v a p e u r .

S o ien t:

ye , le po ids sp éc ifiq u e de l ’eau à la p ie s s io n p où e lle se tro u v e (en k g /m 3^ yv , le p o id s s p é c if iq u e d e l a v a p e u r à la p r e s s io n p où e l le s e tro u v e

(en k g /m 3),y , le p o id s sp é c if iq u e m o y en de l ’é m u ls io n , ve , l a v i te s s e d e l ’eau (en m /s ) ,Vy, la v i te s s e d e l a v a p e u r (en m /s ) ,v , , la v i te s s e re la tiv e de la v ap e u r p a r ra p p o r t à ce lle de l ’eau (enm /s)..

E n t r e c e s d iv e r s e s q u a n t i té s , n o u s p o u v o n s é c r i r e l e s r e la t io n s s u i v a n te s q u i d é f in is s e n t y:

S-у = S e Y e+ S v Yv,S 4 y = SeVeTe + Svv¡,yy


(b)

Figure 3

Disposition des sources e t du détecteur.(a) Cas du cobalt-60. (b) Cas du sodium-24.

Figure 4

Compteur e t source au cobalt.

MESURE DU POroS SPÉCIFIQUE DE L'ÉMULSION (EAU-VAPEUR) 421

L e s tra v a u x de S chm idt, r e p r i s p a r HOSSARD et GAMET [13] p e rm e tte n t enfin d ’é c r i r e la re la tio n

vr =< P(P .S ,Y ).

N ous avons v é r if ié que la v a le u r de Vt é ta i t en a c c o rd avec le s tra v a u x d e S ch m id t, m a is n o u s n e p ré s e n to n s p a s le s c a lc u ls q u i s o r te n t du c a d re d e n o tr e e x p o sé .

3 .2 . M e s u re p a r a b s o rp tio n de ra y o n s g am m a

a) Principe de la méthode

L a m e s u re d e la d e n s ité d ’un m é la n g e eau + v a p e u r p a r a b s o rp tio n de ra y o n s g am m a e s t , n o u s l ’av o n s vu, une m éth o d e e x p é r im e n ta le 'c o n n u e [1,2, 3 ,4 , 5]. L ’éc o u le m e n t e s t su p p o sé p e rm a n e n t e t l e s b u lle s de gaz r é p a r t i e s u n ifo rm é m e n t d an s le liq u id e . L ’a b so rp tio n de ra y o n s g am m a e s t p ro p o r tio n n e lle à la d e n s ité y d e ce m é la n g e . L ’a ttén u a tio n d ’un fa is c e a u é t ro i t d e pho tons p e rm e t de d é d u ire la v a le u r de y.

b) Absorption des rayons gammaÍ

L ’a b s o rp t io n du ra y o n n e m e n t g am m a e s t c a r a c t é r i s é e p a r l a r e la t io n g é n é r a le

I - I i e*11* , (1)

oùI j = in te n s ité du ra y o n n e m e n t in c id en t,I = in te n s ité du ra y o n n e m e n t é m e rg e a n t,x = é p a is s e u r d e l ’a b s o rb a n t en cm ,fi = c o e f f ic ie n t d ’a b s o rp tio n l in é a i r e en c m '1.L e co e ffic ie n t ц e s t r e l i é à la se c tio n e ff ic a c e m ic ro sc o p iq u e d ’a b s o rp

tio n p a r la fo rm u le :

ц = N 0p o-/ À , (2)

où

N0 = N o m b re d ’A vogad ro ,A = p o id s a to m iq u e , a = se c tio n e ff ic a c e m ic ro sc o p iq u e , p = d e n s ité de l ’a b s o rb a n t.D an s l e m o n ta g e u t i l i s é , l ’a t té n u a tio n du f a is c e a u d e r a y o n s g a m m a

o b é i t à l a r e la t io n :

I = I 0 ei*sxs e-Mix, e-My xv , (3)


oùHs = c o e ffic ie n t d ’a b s o rp tio n l in é a i r e du m a té r ia u de s t r u c tu r e , ‘ jUj = c o e ff ic ie n t d ’a b s o rp tio n l in é a i r e du liq u id e , juy = co e ffic ie n t d ’a b s o rp tio n l in é a i r e d e la v a p e u r, x s = é p a is s e u r to ta le du m a té r ia u de s t r u c tu r e ,X[ = é p a is s e u r to ta le du liq u id e , xv = é p a is s e u r to ta le de l a v a p e u r .D an s la su ite i l ne s e r a p a s ten u c o m p te d e l 'a b s o r p t io n d a n s l e s é lé

m e n ts d e s t r u c t u r e , c e l l e - c i é ta n t l a m ê m e d a n s to u te s l e s e x p é r ie n c e s . P a r c o n s é q u e n t l ’éq . (3) d e v ie n t :

N = Nn e _|1l ^ e _|iv xv,

N 0 é ta n t l ’a c t iv i té m e s u ré e p a r l e d é te c te u r lo r s q u e le tu b e e s t v id e e t N l ’a c tiv i té e n r e g is t r é e av ec le m é lan g e eau + v a p e u r s ’éco u lan t dans le tube .

A ux p r e s s io n s u t i l i s é e s d a n s le tu b e , l a d e n s ité de la v a p e u r e s t t r è s f a ib le p a r r a p p o r t à l a d e n s i té d e l ’eau ; l ’a b s o rp tio n d é s p h o to n s d a n s la v a p e u r p e u t donc ê t r e n é g l ig é e . F in a le m e n t l a r e la t io n u t i l i s é e s ’é c r i t

N = N0 e"t|x . (4)

ц e t x é ta n t le c o e ffic ie n t d ’a b so rp tio n e t l ’é p a is s e u r de l ’eau contenue dans le m é la n g e .

c) Dispositif expérimental

Un p r e m ie r d é te c te u r e s t d isp o sé en hau t du tu b e -é c ra n , où l ’on d é s ire m e s u r e r la d e n s ité du m é la n g e v a p e u r - l iq u id e . L a s o u rc e e t le d é te c te u r son t d isp o s é s à l ’in té r ie u r de p ro tec tio n s en plom b qui d é lim iten t un fa isc ea u cy lin d riq u e de ray o n s gam m a de 1 cm de d ia m è tre , qui t r a v e rs e rad ia lem en t le tu b e -é c ra n .

L a s o u rc e e s t c o n s titu é e p a r 5 m e de 60Co q u i é m e t deux r a ie s g am m a de 1,17 e t 1,33 M eV . L e d é te c te u r e s t une sonde à s c in ti l la t io n s c o n s titu é e p a r un c r i s t a l de N al a s s o c ié à un p h o to m u ltip lica teu r du type R adiotechnique 53 A V P. L e d isp o s itif é lec tro n iq u e a s so c ié com prend :- Un p r é a m p l i f ic a te u r q u i a d a p te l ’im p é d a n c e d e s im p u ls io n s e t m u lt ip lie

le u r a m p litu d e p a r 1 ,5 .- Un c i r c u i t é c h e l le e t un c i r c u i t in té g r a te u r q u i d é l iv r e un e te n s io n p r o

p o rtio n n e lle au n o m b re d ’im p u lsio n s re ç u e s ; c e l le -c i e s t m e su ré e de façon con tinue à l ’a id e d ’un e n r e g is tr e u r g raph ique .

U n se c o n d e n s e m b le d e d é te c tio n id e n tiq u e a u p r e m i e r e s t d is p o s é à l a p a r t i e in f é r ie u r e du tu b e -é c ra n .

.d) M is e en œ u v ré d e l a m é th o d e

L e tube é tan t v ide (é p a is se u r d ’eau x= 0) on m e su re lë s taux de com ptage do n n és p a r le s d é te c te u r s s i tu é s en h au t e t en b a s du tu b e . L o rs q u e le r é g im e d ’é q u il ib re de la b o u c le e s t a t te in t, le d é te c te u r p la c é en hau t du tube

MESURE DU POmS SPÉCIFIQUE DE L'ÉMULSION (EAU-VAPEUR) 423

e n r e g i s t r e un n o m b re d ’im p u ls io n s N /m in . C e tte a c t iv i té e s t du e a u m é la n g e g a z - l iq u id e . D ’a p r è s l ’ é q . (4), o n ,a l a r e la t io n x = ( l /^ )L o g ( N 0/N ) .

L a r e la t io n

y l *Ye + (a -x )> t5)

donne l a d e n s i té g a m m a du m é la n g e ; e t yv so n t l e s d e n s i té s de l ’eau e t d e l a v a p e u r , a e s t l e d ia m è t r e i n t é r i e u r du tu b e -é c r a n .

R e m a rq u e : O n p eu t é g a le m e n t c a lc u le r .x à p a r t i r d u c o m p ta g e ob tenu avec la boucle p le in e d ’eau , à cond ition de te n i r co m p te de la v a r ia tio n de ц en fo nction de la te m p é r a tu re . L e d é te c te u r p la c é en b a s du tube p e rm e t de v é r i f i e r l e s r é s u l t à t s o b te n u s ; i l d onne l ’a c t iv i té p o u r x = 6 c m d ’e a u , le tu b e au n iv e a u du d é t e c te u r é ta n t to u jo u r s p le in d ’e a u .

e) P r é c i s io n s û r l e s m e s u r e s

S o ien t t e t to le s te m p s p en d an t le s q u e ls l e s m e s u r e s d e Ñ e t No ( a c tiv i té s p a r m in u te ,c o m p te te n u du b r u i t d e fond de l a so n d e à s c in ti l la t io n s ) so n t e f f e c tu é e s . L a p r é c is io n o b ten u e p o u r N e s t d o n n é e 'p a r l ’e x p r e s s io n

s /(N + n )t +>/nX (N +n) t

où n e s t le b ru it de fond p a r m in u te e t t n le te m p s pendan t le q u e l i l e s t 'm e s u r é .

D e m ê m e , l a p r é c is io n o b te n u e p o u r N 0 e s t d o n n ée p a r l ’e x p re s s io n

>V(N0 + n ) t0 .

(N0 + n ) t0

P a r c o n s é q u e n t n o u s o b te n o n s la r e la t io n s u iv a n te :

A x _ + _1_ (~V(N + n )t + ’y/ntp + J(N 0 + n )t0 + Æ T nx ц цп \ (N + n )t (N0 + n )t0

où n e s t p e tit devan t N (200 cpm poiir 50 000 cpm ). Donc l ’e x p re ss io n (6) peut s 'é c r i r e

A x Au , 1 fJÑt | jN o to l x Ц p n "[ N t N0t 0 J ‘

O r

JN t 1,9 JÑTt¿ 1,7 Nt ” 1000 * N0 t 0 "lOOO

424 C . MAILLE et a l.

e t à 160ЯС on a ц = 0 ,058 ± 0 ,001 . D’où, yv é tan t t r è s fa ib le p a r ra p p o r t à ye, l a v a le u r n u m é riq u e de À x /x s ’é c r i t :

Д х _ 0,001 + 1 Г 1,7 + 1,9 1 _ _1_ J j 3 = _3_x ” 0 ,058 0,058 11000 1000 J " 58 100 100 '

e t p a r conséquen t

Д * + à i = J L + _ L - â i l 5y ~ x a 100 60 - 100 ~ 100 *

3. 3. M e su re p a r d é tec tio n d ’un ra d io é lé m e n t e n tra în é p a r l ’eau

a) Principe de la méthode

On in tro d u it d a n s l a c h a u d iè re e x p é r im e n ta le du 24N a, so u s fo rm e de N aC l qu i s e d is s o u s d a n s l ’e a u . L e 24N a é m e t deux ra y o n n e m e n ts g a m m a de 1,37 e t 2,76 M eV. L a p é r io d e de d é s in té g ra tio n e s t de 15 h . E n p la ç a n t deux d é te c te u r s co m m e p ré c é d e m m e n t e n h au t e t e n b a s du tu b e -é c ra n , on p eu t o b te n ir la d e n s ité du m é lan g e .

b) Dispositif expérimental

L e s d é te c te u rs so n t id e n tiq u e s à ceux qui oht é té d é c r i ts p récéd em m en t. S eu les le s p ro te c tio n s en plom b ont é té m odifiées .L’o u v e rtu re du d iap h rag m ^ c 'e s t - à - d i r e le d ia m è t re du f a is c e a u ,e s t m a in te n a n t d e 3 cm p o u r o b te n ir un e a c tiv i té p lu s im p o r ta n te .

c) Calcul des activités mesurées par les sondes

D é te c te u r p la c é en b a s du tube é c r a n . S o ien t P l a c o n c e n tra tio n en g /k g de 24Na dans l ’eau , N l ’a c tiv ité sp éc ifiq u e de 1 g ra m m e de 24Na e t V le volum e d ’eau vu p a r le d é te c te u r . C e lu i-c i m e s u re l ’ac tiv ité :

T = k 1V YeP N k 2 ,

oùk j =un fa c te u r te n an t com pte de la g é o m é tr ie s o u rc e -d é te c te u r , de l ’ab

so rp tio n d ’une p a r t ie d es photons dans le s p a ro is du tube et de l ’e ff ic a c ité du d é te c te u r ,

ye = po ids sp éc ifiq u e de l ’eau,k2 = f a c te u r te n a n t co m p te d e l 'a u to a b s o rp t io n d ’un e p a r t i e d e s ra y o n s

g a m m a d a n s l ’eau .P o u r s im p l i f ie r le s c a lc u ls on ad m et que V e s t un c y lin d re d e 6 cm de

lo n g u e u r e t de 3 cm d e d ia m è t re . P o u r d é te r m in e r k2 on p re n d une é n e rg ie m o y e n n e d e s r a y o n s g a m m a d e 2 M eV . L e s ta b le s d o n n en t u n c o e f f ic ie n t d ’a b s o rp tio n ц = 0 ,0 5 cm A. P o u r s im p l i f ie r l e s c a lc u ls on c o n s id è r e qu e le d é te c te u r v o it un c y lin d re d ’eau d e d cm d e d ia m è tre e t de a cm d e lo n gueu r (v o ir fig . 5)


Figure 5

Cylindre élém entaire.

S o it dT l ’a c t iv i té d o n n ée p a r un c y l in d r e é l é m e n ta i r e d e h a u te u r dx:

Г . J7 V *d*-

où As e s t l ’a c tiv i té du c y lin d re d ’eau de lo n g u e u r a, é m is e en d ir e c t io n du d é te c te u r . P a r une in té g ra tio n on o b tie n t

T = As. / V ^ d x = Aa l a 1 - e"^

On a donc f in a le m e n t:

T = k 1V 7 e P N ца 1 - e

D é te c te u r p la cé en hau t du tube é c ra n . Le volum e étudié e s t en co re le même, le fa c te u r g éo m é triq u e iden tique , m a is ce vo lum e V con tien t ic i un m élange d ’eau e t de v a p e u r .

V = V + V e v

oùVe = vo lum e o cc u p é p a r l ’ea u ,

= vo lum e occupé p a r la v a p e u r .

Du f a i t de l a v a p o r is a t io n , l a c o n c e n tra tio n en N aC l de l ’ea u e s t p lu s g ra n d e en hau t qu ’en b a s du tu b e . L e vo lum e d ’eau + v a p e u r an a ly sé en hau t du tu b e c o r re s p o n d à un p o id s (Ve ye + Vv-)v) d ’eau qui co n tien t (Л£.Te + % YV)P g ra m m e de 24Na, ce qui c o r re s p o n d à une a c tiv ité to ta le de (VeYe + V ^ P N c p s .

L e d é te c te u r , m e s u re


x é ta n t l ’é p a is s e u r d ’eau c o rre sp o n d a n t au vo lum e Ve . L e ra p p o r t e n tre le s deux a c tiv i té s m e s u ré e s en b a s (T) e t en h au t (t) du tube s 'é c r i t :

ou e n c o re :

_T = _______a It V y + V y e 'e ____ y 'v

Y7 c— b- -j 1 - e-"* j-

_T_ _ x Te (1 - e MJ )__________

* (x7 e + ( a - x ) y v )(1 - e 'MX )

Figure 6

T / t = f (x)

L a co u rb e T / t = f(x) (fig .6 ) p e rm e t de d é te rm in e r x en fonction de T / t obtenu e x p é r im e n ta le m e n t . T / t e s t e n c o re le ra p p o r t d e s a c t iv i té s m e s u r é e s p a r le d é te c te u r p la c é en h au t du tu b e , d an s le c a s où l ’o n n ’a q u e d e l ’e a u e td a n s le c a s oïl l ’on a un m é la n g e e a u + v a p e u r . C ’e s t c e r a p p o r t T / t q u i a é té

, m e s u ré e x p é r im e n ta le m e n t , ce qui a p e r m is é v i te r d ’é ta lo n n e r l e s d é te c t e u r s l ’u n p a r r a p p o r t U l ’a u t r e .


C o n n a issa n t l a v a le u r de x, on en déd u it com m e p ré c é d e m m e n t la d e n s i té g am m a.

d) Précision sur la mesure de l’épaisseur d’eau x

C o n s id é ro n s le r a p p o r t

L e s v a r ia b le s so n t ц , a, x, t , T . On p re n d la d if fé re n tie lle lo g a r i th m ique de c e tte e x p re s s io n :

T v

%4 1 ) л - П Ч - * ) dt_ _ dT

p-t** ” , ' -ма t " Te 1 - e

P a r co n séq u en t

Д хx /их

их

- д а

A t + Д Т + _ aT eMa- l e*1* - 1 J

( a + x ) P - - lД а .

L ’a p p lic a tio n n u m é riq u e con d u it f in a le m e n t à

Ay _ Д х Д а _ 9 8 _ 17У ~ x a ~ 100 100 " 100 ‘ (8)

e) Résultats expérimentaux

L e s r é s u l t a t s o b te n u s so n t r e p o r té s s u r le ta b le a u I.L e s e s s a i s e f fe c tu é s av ec le s d eux m é th o d e s m o n tre n t que l e s r é s u l

t a t s so n t c o n c o rd a n ts aux e r r e u r s e x p é r im e n ta le s p r è s . L a p r é c is io n s u r la m éthode du ,¿4Na e s t m o in s bonne que c e lle ob tenue avec la m éthode 60Co . ■ M a is d a n s le c a s d ’u n e c h a u d iè re in d u s t r ie l le l a m é th o d e du 24N a e s t p lu s fa c ile à m e ttr e en oeuvre . C ’e s t pou rquo i nous nous a ttach o n s à l ’a m é lio re r , l e s r é s u l ta ts que nous venons de d o n n er ne co n s titu a n t qu’une p re m iè re étape de n o tre t r a v a i l .

TABLEAU I

E N SEM B LE DES R ÉSU LTA TS EX PÉRIM EN TA U X

428 C . MAILLE et a l .

Date Heures N /N 0 T / t x У

17-10-61 16 h 10 - 16h 30 30

0. 785 4 ,15 615 ± 30 60 Со

19-10-61 13 h

15 h

17 h 15

0, 79

0 ,82

0, 75

4

3 ,78

4,95

610 t 30

510 ± 26

750 ± 38 no

nО

ОО

20-10-61 16 h 10 0, 79 4 610 ± 30 60 Со

23-10-61 12 h 30-13 h

24 h 10

0, 80

1 ,2

3 ,77 .

4 ,9

575 i 58

745 ± 130

60 Со

MNa

24-10-61 14 h 30 1,38 4 ,2 640 f 110 «N a

26-10-61 16 h 30 0 .80 3,77 575 i 20 60 Со

27-10-61 16 h 30 0 ,81 3 ,6 545 ± 55 60 Со

27-10-61 18 h 30 1.47 3 ,9 590 t 100 24 Na

f ) S o u r c e s d ’e r r e u r s s u r la m é th o d e du 24Na e t a m é lio r a tio n s e n v is a g é e s

Au b ru it de fond p ro p re U tou t m ontage de^détection s ’ajoute ic i l ’ac tiv ité p a r a s i te d es tu b e s v o is in s de c e lu i a l ’é tude . Il s ’ag it donc de p ro té g e r so ig n e u se m e n t le s d é te c te u r s . M a is d an s ce se n s , on e s t l im ité p a r le p o id s du d is p o s i t i f d e p r o te c t io n en p lo m b qui ra p id e m e n t d e v ie n t p ro h ib i t i f . N ous e n v isa g e o n s l ’u t i l i s a t io n d e so n d e k s c in t i l la t io n s d e diam 'fetre p lu s fa ib le (p h o to m u l t ip l ic a te u r R a d io te c h n iq u e 152 A V P, av e c g u id e d e lu m iè r e ) . C eci nous p e rm e t d ’au g m en te r l ’é p a is s e u r de la p ro tec tio n san s tro p en augm e n te r le p o id s . D e p lu s une r é p a r t i t io n p lu s é tu d iée du p lom b to u t au to u r du d é te c te u r a m é l io r e c o n s id é r a b le m e n t l ’e f f ic a c i té d e p r o te c t io n . N ous a llo n s le m o n tre r en ca lcu lan t le ra p p o r t s ig n a l-b ru it dans le cas d ’une s é r ie de 80 tu b e s d isp o s é s en un é c ra n de 5 m de la rg e u r e t de 5 m de h au teu r, en un poin t P s itu é à l ’in té r ie u r du nouveau d isp o s itif de p ro tec tio n dont l ’é p a is s e u r de p lom b e s t de 20 cm . Ce d isp o s itif e s t co n stitu é de s ix é lém en ts d ’un p o id s m oyen de 25 kg. On a s s im ile le tu b e é c ra n à une s o u rc e l in é a i re , de lo n g u e u r 1, d ’a c tiv i té sp é c if iq u e p a r u n ité de lo n g u e u r e t s itu é à la d i s ta n c e a de P .

L ’a c t iv i té d o n n ée p a r un é lé m e n t d l au p o in t P s ’é c r i t ( v o ir f ig . 7)

дdcp = k j B ---- ^ e ' ^ d l

4 ît x

= c o e f f ic ie n t te n a n t c o m p te de l a g é o m é tr ie s o u r c e - d é te c te u r e t de l ’e f f ic a c i té du d é te c te u r ,

B = « b u ild -u p f a c to r» ou f a c te u r d ’a u g m e n ta tio n ,Ae = a c t iv i té p a r u n ité d e lo n g u e u r en d é s / s - cm ,x = d is ta n c e d e l ’é lé m e n t d e l à s o u r c e au p o in t P ,ц = c o e ff ic ie n t d ’a b s o rp tio n l in é a i r e du m il ie u a b s o rb a n t.

MESURE DU POIDS SPÉCIFIQUE DE L'ÉMULSION (EAU-VAPEUR) 429

Figure 7

Activité donnée par un élém ent dl au point P.

L ’a c tiv i té Ф p ro v o q u ée au p o in t P p a r le tube e n t ie r , e s t donnée p a r la fo rm u le

_ 0 1 0 2

Ф = ф1 + ф2 = [f e ‘ / C ° S e > d 0 + f е̂ 'ССКв) d 6

0 0

où cpj e t ф2 so n t le s a c t iv i té s d o n n ée s p a r le s p a r t i e s in f é r ie u r e s e t s u p é r i e u r e s du tu b e . On a n é g lig é l ’a b s o rp tio n d an s l ’é p a is s e u r ( a - r ) d ’a i r , r é ta n t l ’é p a is s e u r du m a té r ia u a b s o rb a n t.

A p p lic a tio n s n u m é riq u e s

I o C a s d ’u n s e u l tu b e , le m il ie u é ta n t c o m p o sé d e 10 c m d ’a i r e t de 20 c m d e p lo m b .

L e s a u t r e s d o n n ée s so n t le s s u iv a n te s : a = 30 cm , r = 20 cm , B = 5 cm , ц = 0 ,47 c m ^ p o u r d e s p h o to n s d e 2 M eV, ц г = 9 ,4 .

Si on s e p la c e au c e n tr e du tu b e , le f lux en P e s t m ax im u m e t on a le s é g a li té s

‘ S1 °! - ' ■Г '-(I tf /c o se ) Г -( |ir/cos0 )% = e2 et / e de = / e de.


P a r une in té g ra tio n g raph ique , on tro u v e , p o u r 35° < 0 < 90°, que chacune d e s in té g ra le s a p o u r v a le u r 5 ' 10"5 ..

On déd u it la v a le u r de Ф:

ф= 5klAe . -ЮГ4 = 4kiA e..„ • 10~5=0,13 • 10Г5 k.A d é s / s 4тга a l e '

Si l ’on in tro d u it d an s le tu b e une a c tiv ité de 10 m e p a r 100 1 d ’eau so it 37 • 102 d é s /s - c m ? Ae= 7 ,3 - 104 d é s / s - cm e t d an s ce c a s ф = k , • 9 ,5-10-2 d é s / s .

2° S é r ie d e 80 tu b e s d is p o s é s en é c r a n

L e p o in t P s e tro u v e au c e n tr e de l ’é c ra n , en fa c e du tu b e c e n tr a l . L e flux g am m a y s e r a donc m ax im u m . On ca lc u le l ’a c tiv ité ï j d ’un d em i é c ra n . E n p r e m iè r e ap p ro x im atio n on peu t d ir e que chacun d es c inq p r e m ie r s tubes in d u iro n t en P l a m ê m e a c tiv ité que le p r e m ie r , le s c in q su iv a n ts la m êm e a c tiv ité que le s ix ièm e e tc . S u r la f ig u re le s ac tiv ité s de chacun de ce s tubes so n t d é s ig n é e s p a r cpj, cp6, . . . l e s é lo ig n e m e n ts du p o in t P p a r ap ag . . j

Ca lc u l d e on a vu d a n s l ’ap p lic a tio n n u m é riq u e p ré c é d e n te que cp =4 • 10-5 k jA g /a .A vec a j = 30 с т ,Ф 1 = 5Çj= 0,65 .1 0 5 k jA e d é s / s ,

ep a = 4 1 c m , Ф = 0 ,485 • 10"° k A d é s / s ,6 6 6 1 e

Ф1 1а 1 1= 66 cm , Фи = 0 ,3 • 10"5 kjA e d é s / s ,

Ф ,.а , = 9 4 c m , Ф = 0 ,2 1 -ÎO*5 k A d é s / s ,- 16 16 16 J лœ a = 124 cm , Ф = 0 ,160 • 1(Г5 k A d é s / s ,21 21 21 l e 7

<P26a26= 153 Cm» Ф26 = ° '13 •10’5 кЛ déS/ S*Ф з ^ ^ 182 cm , Ф31 = 0 ,1 1 0 -1 0 '5 к Д d é s / s ,

ф3ба3б= 212 c m » ф36 = °*094 ‘ 10' 5 k iAe d é s / s .

P a r co n séq u e n t^ = ЕФП = 2,13 • 10*5k1Ae d é s / s .

F in a le m e n t l ’a ç tiv i té to ta le en P , à t r a v e r s 20 cm d e p lo m b e t 10 cm d ’a i r , due è. to u t l ’é c r a n , s ’-éc rit

У = 2¥j. = 4,26 • 10'5 Aekx d é s / s .

g) Rapport signal-bruit R

A 30 cm d ’un tu b e s u r le q u e l p o r te l a m e s u re avec un c r i s t a l s c in ti l la - t e u r de 3 cm de d ia m è tre , le s ig n a l S e s t donné p a r

S = 2 ,2 - 10’2 k]A s ,

où A s e s t l ’a c tiv i té p a r u n ité de vo lum e te l le que

A, = ir(2,5)2 Ajp a r su ite :

2,2 • 10 k A _ S _ 1 s

R " ^ “ 4,26 •10-5T(2,5)2 k1A s " 26,5 ’

Ce ra p p o r t R, co m p a ra tiv e m e n t à ce lu i que nous avons obtenu au co u rs d e s p r e m ie r s e s s a is , e s t to u t à fa it a c ce p ta b le e t nous pouvons e s p é r e r obt e n i r une p r é c is io n c o m p a ra b le 'à c e lle de la m éth o d e u ti l is a n t l ’ab so rp tio n d ’un fa isc e a u de ray o n s gam m a; d ’au tan t p lu s que nous nous so m m es p la c é s d an s le s p lu s m a u v a is e s co n d itio n s p o u r le c a lc u l du ra p p o r t s ig n a l -b ru i t . P a r a i l le u r s , nous avons d an s nos d e r n ie r s c a lc u ls , n ég lig é l ’a u to -a b so rp - t io n d ’une p a r t i e du ra y o n n e m e n t d an s l ’ea u , é ta n t donné q u ’e l le n ’e s t que d e l ’o r d r e d e 10 à 15% 115 J .

MESURE DU POroS SPÉCIFIQUE DE L'ÉMULSION (EAU-VAPEUR) 431

CONCLUSION

L e s e s s a i s que no u s av o n s e ffe c tu é s s u r une c h a u d iè re e x p é r im e n ta le m o n tre n t que la m éthode de m e s u re de la d en s ité d ’une ém u lsion e a u -v ap eu r p a r ad d itio n de ra d io é lé m e n ts d an s l ’eau , donne d e s r é s u l t a ts c o m p a ra b le s k. ceux que l ’on o b tie n t avec la m éthode de l ’a b so rp tio n d ’un fa is c e a u de r a yons g am m a, e t en a m é r l io r a n t le d is p o s it if de p ro te c tio n du d é te c te u r , on p eu t e s p é r e r o b te n ir une a u s s i bonne p ré c is io n .

C ette m éthode a l 'av a n tag e d ’ê t re sim p le e t de ne p as p e r tu rb e r l ’écou lem e n t d e l ’e a u . E l le d o it t r o u v e r un e a p p lic a tio n in té r e s s a n te d a n s l ’é tu d e e x p é r im e n ta le de l a c i rc u la t io n d a n s l e s c h a u d iè re s .


[1] WAESELYNCK, R ., Etude de la circu lation naturelle dans les tubes de chaudières, Ass. Tech. Mar. e t A ér., (1948).

[2] SCHWARZ, K . , Untersuchungen über die W ichteverteilung die Wasser und Dampfgeschwindigkeit sowie den Reibungsdruckabfall in lotrechten und waagrechten Kesselsteigrohren, Ver. Deut. Ing. Forschungsh.445 (1954).

[3] HOURS, R ., Mesure de la concentration en gaz d 'une ém ulsion g a z-liq u id e par absorption de rayons gam m a, M émoires & travaux de la S. H. F. (1 6 -6 -5 5 ) .

^ [4 ] LOTTES, P. A. .and FLiNN, W .S ., A m ethod o f analysis of natu ral c ircu la tion boiling systems, Nuc. Sci. Eng. 1 (1956).

[5] 1SB1N, H. S . , SHER, N .C . and EDDY, K .C ., Void fractions Intw o-phase steam -w ater flow ,Amer. Inst. Chem . Eng. J. 3, 1 (1957).

[6] LAIRD, A. M ., SCOTT, A.W . and THOMSON, A .S .T . , Natural circulation investigations on an experim ental tw o-tube boiler, B.S.R. A. (7 March 1958).

[7] PETRICK, M ., Two-phase A ir-water flow phenom ena, ANL-5787 (1958).[8] COOK, W. H . , Boiling density in v e rtica l rec tangu lar m u ltichannel sections w ith na tu ra l c ircu la tio n ,

ANL-5621 (1956).[9] RICHARDSON, B. L ., Some problem s in horizontal tw o-phase tw o-com ponent flow , ANL-5949 (1958).

432 C . MAILLE et al.

[10] HOOKER, H. H. and POPPER, C .F . , A gam m a ray attenuation m ethod for void fraction determ inations in experim ental boiling h ea t transfer test fac ilities , ANL-5766 (1958).

[11] JAROSCHEK, K. and BRANDT, F . , Entwicklung eines Diagramms zur Berechnung des natilrlichen Wasser- um laufs in W asserrohrkesseln und Siedew asserreaktoren, Brennstoff W ârm e-K raft, 12, 5 (1960) 189.

[12] HUGUES, T . A. and MARKET, W ., S team -w ater m ixture studies in a v e rtica l p ipe a t high pressures, Babcok and W ilcox C o . , Research C en ter A lliance Ohio (D ec. 1960).

[13] HOSSARD, A. and G A MET, C ., C irculation dans les chaudières. Document Stein & Roubaix S. 314 (Juin 1949).

[14] DENGLER, C .E ., Mass. Inst. T ech .(1947).[15] FIELD, F.L. Nucleonics, 1 1 ,9 (1953) 66.

D I S C U S S I O N

E . SOMER: D r. H ours f ro m S aclay has po in ted out in th e pub lica tionyou quote in y o u r l i s t of r e fe re n c e s th a t changes in the s iz e of s te am bubbles a ffe c t th e r e s u l t s o f w a te r - s te a m r a t io d e te rm in a tio n s , th u s g iv ing r i s e to e r r o r s . Y ou d id no t m e n tio n th is e ffe c t in y o u r p a p e r . I shou ld be i n t e r e s te d to know w hat im p o r ta n c e shou ld be a tta c h e d to th is e ffec t b e c a u se we shou ld l ik e to m a k e u se of it fo r d e te rm in in g bubble s iz e in s y s te m s w h ere th e w a te r - s t e a m r a t io i s known.

C. M AILLE: We did not in v e s tig a te th e effec t of bubble d ia m e te r . Theo b je c t of th e e x p e r im e n ts w as to c o m p a re o u r m ethod w ith the m ethod u sing g a m m a r a y s f ro m an e x te r n a l s o u r c e . I b e lie v e th a t th e e f fe c t o f bu b b le d ia m e te r w ould b e th e s a m e in b o th c a s e s , w ould i t n o t?

E . ' SOMER: No, I do not th in k th a t the s iz e of th e bubbles would affec tth e s o d iu m -24 m e th o d to th e s a m e ex ten t as i t w ould th e c o b a l t- 60 m e th o d .

C . M A ILLE: W ell, th a t m ay be so , but I am in te re s te d in th is p ro b lem f ro m th e p o in t of v iew of th e b o i le r -m a k e r . W hat we a r e try in g to find out i s w h e th e r th e r e i s a g r e a t d if fe re n c e in d e n s ity b e tw e en one tu b e ahd a n o th e r . W e a r e n o t lo o k in g fo r v e ry h igh p r e c is io n .

I shou ld add, by th e w ay, th a t we m e a s u re d th e d en s ity only o v e r a n a r ro w s l ic e of tu b e and o u r r e s u l t s do not r e f le c t th e a v e ra g e d e n s ity . J a ro s c h e k and S chw arz h av e developed a m eth o d fo r c o r re c t in g th e d en s ity m e a s u re d o v e r a s l ic e of tu b e to th e a v e ra g e d en s ity .

R . CORNUET (C h airm an ): I shou ld be in te re s te d to know w h eth e r d e p o s it io n of th e t r a c e r on th e w a lls o f th e tu b e s in th e b o i le r in te r f e r e d in an y w ay w ith y o u r m e a s u r e m e n ts .

C . M A IL L E : W e d id c h e ck th a t and d id no t find any t r a c e r d e p o s itsin th e tu b e , w hich had v e ry sm o o th in n e r w a lls . In any c a s e , v e ry l i t t le of th e ra d io iso to p e w as in s e r te d and t e s t s only la s te d a s h o r t t im e .

R . CORNUET (C h a irm an ): W hen we c a r r i e d out s im i la r te s t s - a t th eN u c le a r R e s e a r c h C e n tre a t G re n o b le , we e n c o u n te re d d if f ic u lt ie s no t only on th a t s c o re bu t a lso b ec au se we found th a t the so lu b ility of the t r a c e r (Na24) v a r ie d a s a fu n c tio n o f te m p e r a tu r e . W e w ere" a l s o r a t h e r w o r r ie d abou t th e d e c a y o f th e t r a c e r , w h ich m e a n t m a k in g f a i r ly d e l ic a te c o r r e c t io n s .

C . M A ILLE: A t th e te m p e r a tu r e a t w hich we p e r fo rm e d o u r e x p e r im e n ts (in th e re g io n of 140°C) no s o lu b i l i ty p ro b le m s a r o s e . A s f o r N a24 d ecay , no c o r re c t io n w as n e c e s s a r y b ec au se we took s im u ltan eo u s and com p a r a t iv e m e a s u r e m e n ts w ith d e te c to r s p la c e d a t th e to p an d ' a t th e b o tto m of th e tu b e .

H ELD AT V IEN N A , 5 - 9 N O V EM B ER 1962

SEMINAR ON PRODUCTION AND USE OFSHORT-LIVED RADIOISOTOPES FROM REACTORS

CHAIRM EN O F SESSIONS

I. L .G . ERW A LL

C . TAYLOR

H . D. YASHIN

HI. D . YASHIN

P . C . A EBERSO LD

R .C . CORNUET

IV. E . SOMER

V. P . GUINN

V . K . SCH EER

W. JASINSKI

V I. W. JASINSKI

Iso to p te k n isk a L a b o r a to r ie s S tockholm

A tom ic E n e rg y R e s e a r c h E s ta b lis h m e n t, H arw e ll

USSR A cad em y of S c ie n c e s , L e n in g ra d

USSR A cadem y of S c ie n c e s , L e n in g ra d

Iso to p e s D ev e lo p m en t, U n ited S ta te s A tom ic E n e rg y C o m m iss io n , W ash in g to n , D .C .

C e n tre d 'é tu d e s n u c lé a ir e s , G ren o b le

D an ish Iso to p e C e n tre , C openhagen

G e n e ra l A tom ic D iv is io n ,G e n e ra l D y n am ics C o rp o ra tio n ,San D iego , C a lif .

U n iv e rs ity of H e id e lb e rg

In s titu te of O ncology, W arsaw

In s titu te of O ncology, W arsaw

SEC R ETA R IA T O F TH E SEMINAR

S cie n tif ic S e c r e ta r ie s :

E d ito r :

R e c o rd s O ff ic e rs :

M. COHEN

J . F . CAMERON

E .M . COUNSELL

T . J . JONES D. J . M ITC H ELL

A d m in is tra tiv e S e c re ta ry : P . GHELARDONI

D iv is io n of I so to p e s , IAEA

D iv is io n of R e s e a r c h and L a b o r a to r ie s , IAEA

D iv is io n of S c ie n tif ic and T e c h n ic a l In fo rm a tio n , IAEA

D iv is io n of L an g u a g es , IAEA

D iv is io n of S c ie n tif ic and T e c h n ic a l In fo rm a tio n , IAEA

433

I A E A S A L E S A G E N T S

ARGENTINAEditorial Sudam ericana, S. A.Alsina 500 Buenos Aires

AUSTRALIAM elbourne University Press 369, Lonsdale Street M elbourne, C. 1

AUSTRIAGeorg Fromme & Co.Spengergasse 39 V ienna V

BELGIUMO ffice In ternational de Librairie 30, avenue M amix Brussels 5

BRAZILLivraria Kosmos Editora Rua do Rosario, 135-137 Rio de JaneiroA g en d a Expoente Oscar M. Silva Rua X avier de Toledo, 140-1° Andar (C aixa Postal N* 5.614)SSo Paulo

BURMASee under India

BYELORUSSIAN SOVIET SOCIALIST REPUBLIC See under USSR

CANADAThe Q ueen's Printer O ttaw a

CEYLONSee under India

CHINA (Taiwan)Books and Scientific Supplies Service, L td .,P .O . Box 83 Taipei

DENMARKEjnar Munksgaard Ltd.6 NOrregade Copenhagen К

ETHIOPIAG .P . Giannopoulos In ternational Press Agency P .O . Box 120 Addis Ababa

FINLANDA kateem inen K irjakauppa Keskuskatu 2 Helsinki

FRANCE and FRENCH UNION Masson e t C ie , Editeurs 120, bd Saint-G erm ain Paris VIe

GERMANY, Federal Republic of R. Oldenbourg Rosenheimer Strasse 145 M unich 8

ICELANDHalldór Jónsson

j M jôstræ ti 2 Reykjavik

INDIAO rient Longmans Ltd.17, C hittaranjan Ave.C alcutta 13

ISRAELH eiliger and Co.3 Nathan Strauss Street Jerusalem

ITALYAgenzia Editoriale Intem azionale Organizzazioni Universali (A .E .I .O .U .)V ia M eravigli 16 Milan

JAPANMarnzen Company Ltd.6, Tori Nichome Nihonbashi P. O. Box 605 Tokyo Central

KOREA, Republic ofThe Eul-Yoo Publishing Co.5 ,2 -k a Chong-ro Seoul

MEXICOLibrería Internacional Av. Sonora 206 M exico 11, D .F .

MONACOThe British Library 30, bd des Moulins Monte Carlo

MOROCCOCentre de diffusion docum entaire du B .E .P .I.8, rue M ichaux-Bellaire (В. P. № 211)Rabat

NEPALSee under India

NETHERLANDSN .V . Martinus Nijhoff Lange Voorhout 9 The Hague

NEW ZEALANDW hitcombe & Tombs, Ltd.G .P .O . Box 1894 W ellington, С. 1

NORWAYJohan Gibndt Tanum Karl Johans g a te 43 Oslo

PAKISTANK arachi Education Society Haroon Chambers South Napier Road P .O . Box N o .4866 K arachi, 2

PARAGUAYA gen d a de Librerías de Salvador N izza C alle P te. Franco No. 39-43 Asunción

PERULibrerfa In ternacional de l Peni S.A . Boza 879 (C asilla 1417)Lima

PHILIPPINESThe M odem Book Company 508 R izal Avenue M anila

POLANDOirodek Rozpowszechniana Wydawnistw Naukowych Polska Akadem la Nauk Palac Kultury i Nauki Warsaw

PORTUGALLivraria Rodrigues 186, Rua do Ouro, 188 Lisbon 2

SOUTH AFRICAVan Schaik's Bookstore (Pty) Ltd. Libri Building Church St.(P. O. Box 724)Pretôria

SPAINLibrería Bosch Ronda Universidad, 11 Barcelona

SWEDENС. E. Fritzes Kungl. Hovbokhandel Fredsgatan 2 Stockholm 16

SWITZERLAND Librairie Payot 40, rue du M arché Geneva

SYRIAGeorges N. Coussa Im m . Chanan rue Khan e l-H arir (B .P . 779)Aleppo

TURKEYLibrairie H achette 469, IstiklSl Caddesi Beyoglu, Istanbul

UKRAINIAN SOVIET SOCIALIST REPUBLIC See under USSR

UNION OF SOVIET SOCIALIST REPUBLICS M ezhdunarodnaya Kniga Kuznetsky Most, 18 Moscow G-200

UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND

Her M ajesty's Stationery Office P. O. Box 569 London, S .E .l

UNITED STATES OF AMERICA National Agency for International Publications, Inc.801 Third Avenue New York 22, N .Y .

YUGOSLAVIAJugoslovenska Knjiga T erazije 27 Belgrade

IAEA publications can also be purchased re ta il at the United Nations Bookshop at United Nations Headquarters, New Y ork , a t th e new s-stand a t the Agency's H eadquarters, Vienna, and a t most conferences, symposia and seminars organized by the Agency.

Orders and inquiries from countries where sales agents have not yet been appointed may be sent to:

Distribution and Sales Unit, International Atomic Energy Agency,Kam tner Ring, Vienna I, Austria

END OF VOL. I

INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA 1963

PRICE; North America= US $8.50 Elsewhere= Sell 178,50 (51s.stg; NF 34,DM 29,80)

production and use of short-lived radioisotopes from reactors

Documents