w

ÅE-45

Measurement of Radioactivity in

the Human Body.

IÖ. Andersson and I Nilsson

AKTIEBOLAGET ATOMENERGI

STOCKHOLM • SWEDEN • I960

AE-45

RFR4 JÅN, m\

MEASUREMENT OF RADIOACTIVITY IN THE HUMAN BODY.

I. Ö. Andersson and I. Nilsson

Summary:

A body counter with a steel room and a 4-inch-diameter by 4-inch-

thick Nal scintillation counter has been in operation since February 1958.

It is used to control the internal contamination in people working with

radioactive materials. Measurements have also been made on the natural

activity in the human body. The average cesium-137/potassium ratio in

a group of Swedish males was in May 1959 73 fJ.|ac per gram of body po-

tassium and in June 1960 55 |J.|JLC per gram of body potassium. The cessation

of the nuclear bomb tests has caused a decrease in the cesium level in

people. This gives some information of how cesium is entering the biosphere.

Printed and distributed in December I960

LIST OF CONTENTS

Page

1. Introduction 3

2. The apparatus and its characteristics 3

3. Calibration 5

4. Measurements of cesium and potassium body contents

in Swedish people 7

5. Measurements of internal contamination 9

6. Human Body Counter. No. 2 11

References 13

Table I. 15

Table II. 16

FIGURES

Fig. 1. Lay-out of the equipment

2. Scintillation detector

3. Background 100 - 1750 Kev and a net human spectrum

4. Background 200 - 3500 Kev

5. Phantom— 8 — &

6 . 10 "yc K42 in man and 10 -yc K40 in phantom spectra

7. Cs 137 in phantom

8. Phantom spectrum matching the human spectrum

9. Measurement with street clothes

10. Cs 137, K 40 and bremsstrahlung bands

11. Histograms of Cs and K in males 1959

12. Zn 65 in man

13. Br 82 in man

14. Sr 90-Y 90 in phantom

15. Natural uranium in phantom

16. Studsvik Body Counter localities

Measurement of Radioactivity in the Human Body.

1. Introduction

Health physicists in many laboratories now use total body counters to

estimate body burdens of radioactive materials, The direct external measure-

ment with a body counter is in most cases a more convenient and accurate

method than estimating the body burden from excretion data. The extremely

low value of the maximum permissible total body burden of many nuclides

(0, 1 \3.c for Ra) imposes a rather severe requirement on counter sensitivity,

especially if it is desired to make measurements below the tolerence level

and in the region of natural activity (0, 01 \xc). The human body counter

technique has therefore been quite specialized. The detector must have a

very high sensitivity, it must be mounted in a special low background room

with 10-20 cm iron shielding and the construction materials must be par-

ticularly selected to have a low content of radioactive substances.

i

The body counter, which has been built at our laboratory became

operational in February 1958. It has been used to control internal conta-

mination in people and to make periodic measurements of the natural ac-

tivity in a group of Swedish people.

2. The apparatus and its characteristics

A layout of rthe apparatus is shown in Fig. 1» The- radiation detector

(Fig. 2) is a scintillation counter with a 4" diameter by 4" thick tallium-

activated sodium iodide, crystal. The crystal is packaged in an electrolytic

copper can with a quartz windowtand coupled, to an EMI. 9530 5IJ diameter

tphotomultiplier tube. A cathodejfollower-type preamplifier feeds the pulses

from the photomultiplier, to a 70-channel pulse height analyzer of the

Hutchinson-Scarrot type.

The detector unit can be. raised or-lowered and carriage arrangement

permits motion in a horizontal direction, which makes it possible to scan

a person placed on a stretcher.

In a routine investigation the subject is placed in a chair which slopes

ards at an angle of 45 and the centre of the

ted 40 cm from the back and the seat of the chair.

backwards at an angle of 45 and the centre of the detector crystal is loca-

To measure radioactivity in the human body down to natural levels it

is necessary to have a good radiation shielding around the detector and the

subject._ The shielding is in this case built of massive steel stabs of naval

armour-plate forming an iron room with inner dimensions 80 cm wide x

90 cm high x 270 cm long. The thickness of the shield is about 20 cm,

except for the door, which is 10 cm thick. The total weight is 23 tons. The

iron room is ventilated with filtered air.

The detector is sensitive to gamma-radiation with energies above

50 Kev and supplies information about the energy of the gamma photons,

which makes it possible to identify the gamma emitting isotope. The energy

resolution on Cs 137 (662 Kev) is 8, 0 %.

The background radiation inside the shield and its stability in time

determines the lowest measurable activity. Fig. 3 shows the spectrum of

the background radiation in the energy range 100 - 1750 Kev. As a com-

parison the spectrum of the natural activity from a person sitting in the

chair is indicated. The number of counts from background is 33, 000 cph

and from the human body 18. 600 cph. The background radiation comes

mainly from the detector assembly itself. There is a peak at 1, 46 Mev

from K 40 which exists both in the crystal and in the glass of the phöto-

multiplier where also radium and-'thorium can be found {Fig. 4). There

are now available sodium iodide crystals and photomultipliers which are

made particularly for low background-work. They should reduce our back-

ground by about a factor of two. Contributions to the background are also

made by small amounts of radioactivity in the shielding material and also

from the hard cosmic radiation. No time fluctuations in the background

have been observed.

Investigations of the different sources that contribute to the background

in shielded scintillation counters have been reported (10).

5.

The two peaks in the human gamma spectrum can be seen in all people

at the present. The peak at 1, 46 Mev is due to K 40 which is .a naturally-

occurring isotope of potassium. The amount of potassium in a typical adult

is 140 grams, emitting 420 gamma photons per second. The peak at 0, 662 Mev

is due to Cs 137, a nuclear bomb fallout product. It was first detected in

people 1955 (11), and the body content has been increasing since then. In

the spring of 1956 it was about 5 m \xc (I). At present the body burden jjs

about 8 m fxc. There is a considerable spread both geographical and in-

dividual.

3. Calibration

To be able to relate the counting rate in a particular photo peak to the

absolute amount of the gamma emitting isotope in the body it is necessary

to calibrate the apparatus by using known amounts of the radioactive substance.

'The calibration can always be done by administration of an additional known

quantity of the same radioelement, This technique is applicable in practice

only to radioelements of short physical half-life or a short effective half-

time in the body. With'elements of long biological half-time it is possible

to use "phantoms" in which one can reproduce the distribution of the iso-

tope in the body as well as the scattering and absorbtion properties.

The potassium calibration of bur detector has been performed by

using two methods,

a) administration of K 42 in man, and

b) measurements with a phantom, filled with a potassium solution.

K 42 emits a gamma ray of the energy 1, 52 Mev which differs only

slightly from the energy emitted by K 40 (1, 46 Mev). K 42 has the very

convenient half-life of 12, 4 hr and when administered to a human being, it

attains equilibrium with K 40 in a period of about 12 hourc (3, .12).

Four subjects of different body constitution were given a drink con-

taining 2 |ac K 42. The standardization of the solution was made by" a 4ir

proportional counter (8). The investigations that could be carried out were

a) to calibrate the detector for K 40 in man

b) to obtain the pure K 40 gamma spectrum from man

c) to study the response for different body constitutions. '

The results are given in Table 1» The detection efficiencies for the

four subjects were measured with two different detector positions. In

position 1, with the centre of the detector 40 cm from the seat and back

of the chair, the efficiency is essentially independent of the height and

weight of the subject. The average photopeak gamma efficiency of the

four subjects was 0. 106 % with a maximum deviation of 3> 7 % of that, value.

A potassium calibration was also made with a phantom (Fig. 5),

which is composed of right circular and elliptical cylinders with dimensions

to approximate an adult human. The phantom was filled with a solution of

natural potassium and measured with the detector in position 1. In Fig. 6

the spectra are shown from 10 gamma curie K 42 in a man (75 kg) and

10" gamma curie of K 40 in a water solution in the phantom (72 kg). The

conformity of the two curves indicates that in the case of potassium the

water filled phantom has che same attenuation and scattering properties

as the human body. The phantom measurement gave exactly the same

photopeak gamma efficiency 0. 106 % as obtained in the K 42 measurement.

Cesium is chemically and metabolically similar to potassium. Since

a potassium solution in the phantom, was a good approximation of the po-

tassium distribution in the body it seems reasonable to assume that the

phantom filled with a standardized cesium solution should give a good

calibration constant. Using this method the photopeak gamma efficiency

0. 168 % was obtained for Cs 137. in man. The shape of cesium in the

phantom spectrum is shown in Fig. 7.

A combination of the Cs and K phantom, spectra gives a good adap-

tation to the normal human gamma spectrum except in the low energy-

region (Fig, 8) where the counting rate from a person is 0 - 10 % higher

than that from the phantom. Our measurements indicate that this is mainly

due to surface contamination of radium daughters and radium in the human

body and not because of a difference in scattering properties between the

phantom and the human body. If the subject does not take a shov/er and uses

his normal street clothes there is definitely an interference from radium

daughters (Fig, 9) (13). Each subject therefore showers thoroughly before

being counted and each wears a special low-background dre o s during the

measurements,

The energy bands used for the estimation of the cesium and potas-

sium body content are shown in Fig» 10, Potassium gives a contribution

in the cesium band which can be calculated because the shape of the pure

K 40 spectrum is known (Fig. 7). The statistical accuracy obtained for a

typical adult by a one hour measurement (Fig. 10) is - 3, 5 % or - 5 grams

for potassium and - 4 % or - 0, 3 mfic for cesium,

A check on the calibration constants was obtained when we measured

a man, who had been measured in the Argonne Human Spectrometer. The

ANL estimate of the body content was 136 grams potassium and 10, 3 mfJLC

Cs 137. Our estimate was 138 grams potassium and 10, 5 m}.ic Cs 137 (3, 13).

The values are in excellent agreement.

4. Measurements of cesium and potassium body contents in Swedish people,.j I.I . , • - • • ! — — — — —

We make periodic measurements;.on,the natural gamma activity in

a group of Swedish people* It is qf course-important to know the natural

activity levels and their individual spread because this gives a sort of

background when making measurements pn internal contamination. It is

also interesting to investigate the cesium level,in people in our country.

A group of 27 adult males, from-the Stockholm area were measured

during May 1959 (3). The results are shown in histograms-in,Fig. 11. The

average potassium content was 2. 20 grams per kg body weight with a

standard deviation of 13 %. This standard deviation exceeds the experimental

error which indicates a considerable biological variation. Potassium is

concentrated in the muscle tissue so the amount is dependent on the body-

constitution and also on the age and sex (2). Our value is in agreement

with the results of many others (4, 15, 17).

The average cesium body content was 10, 8 mj-ic or 73 |J.fJ.c per gram

body potassium with a standard deviation of 28 %.

The main process through which people get cesium into the body is

by ingestion of food which is contaminated through soil integration and

plant uptake or direct fallout on vegetation. In this country as in countries

with similar food habits, dairy products seem to make the major con-

tributions. Differences in diet customs give different cesium body con-

tents. The lowest cesium value we found was 5, 3 mjac and the highest

was 20, 1 m(xc.

In Table 2 the Cs/K ratio in people measured at some other labo-

ratories is listed.

10 subjects were measured again in June 1960. The average Cs/K

ratio had decreased from 74 up.c/gK to 55 p.|j.c/gK from May 1959 to June

I960. This decrease is quite interesting because it gives an indication of

how Cs 137 is entering the biosphere. The question has been raised whether

Cs 137 is entering the biosphere largely through'direct fallout on vege-

tation or via the soil. This is an important question. If entry is via direct

contamination, Cs 137 levels in people will come into equilibrium with

the stratospheric fallout rate and continuation of weapons tests at the past

rate will produce relatively small increase in the Cs 137 body burden of

the population. If entry is via the soil continued testing at the past rate

may result in än equilibrium level in people (in about 100 years) that will

be from ten to fifteen times the present level. Cessation of tests would,

in the former case result in an immediate decline in the Cs 137 levels in

people at a rate comparable to the half-life of stratospheric fallout. In

the latter case the levels in people would continue to rise and reach a

maximum in about 1965 (7).

There have not been any nuclear bomb tests since Okt. 1958, -except

for the small French one. The decrease in the Cs 137 level in people which

we have found thus indicates that a considerable part of the Cs 137 is en-

tering the biosphere via direct fallout. Measurements on eight control

subjects at Argonne have also shown tliat the average Cs/K ratio had

decreased, from 64, 4 (j,[xc/gK in June 1959 to 55 jJifJ-c/gK in December 1959

(13). • .

Cs, 137, like potassium, is concentrated in muscles and the radiation

dose it delivers is essentially whole body. The dose from the present level

of_ Cs 137 is about 1 mr/year. This is., about 5 % of the dose from natural

K-40 or about 1 % of the dose from the natural background radiation.

5. Measurements of internal contamination.

The main purpose of our body counter is the identification of suspected

internal contamination. So far we have fortunately had only a few cases, all

of them below dangerous levels.

Zinc-65 was found in five subjects, who had done maintenance work

on the tank of the research reactor R 1. A typical spectrum is shown in

Fig. L?« Zn 65 is produced by neutron interaction with stable zinc. It has

a half-life of 245 days and emits a gamma fay of energy 1, 12 Mev. The

excretion rate was studied until a month after the administration and the

effective half-time in the "body was found to "Be 22 - 3 days. Zn 65 in people

working around reactors has also been reported by others (14).

'The spectrum of a subject with bromine - 82 in the body is shown in

Fig. 13. A leaking ampul containing neutron activated bromine had caused

the-intake. Br 82 has a short, half-life (36 hr)« The body content was esti-

mated-to 0, 1 (JLC.

The sensitivity of the detector is sufficient_to detect body burden much

below recommended tolerance levels for all beta-gamma emitting isotopes.

10 .

In all the above cases for example the body burdens were much below tole-

rance levels. ICRP 1959 gives the MPBB for Zn 65 as 60 \xc and for Br 82

as 10 (AC.

-3A one hour measurement offers the possibility of detecting 10 JJLC

of a 100 % gamma emitting isotope distributed in thejbodydf the gamma

energy is above 50 Kev. MPBB is in the region 0, 3 - 300 |xc. !

Pure hard beta emitters can be detected by means of bremsstrahlung.

Fig. 14 shows the spectrum from 1 (JLC Sr 90 - Y 90 in the phantom. The

ultimate sensitivity is dependent on how exact the subject's spectrum from

the natural activity is known in the low energy region. (Fig. 10).

We use the information about the shape of the spectra obtained from

the phantom measurement to calculate the number of" counts in the low

energy region that corresponds to the subject's cesium and potassium

levels. The difference between the measured and calculated count råtes

is then used to indicate the amount of bremsstrahlung. The lowest detec-

table body burden of Sr 90 - Y 90 in a one hour measurement with our

equipment is 0, 1 |xc or l/20 of the MPBB in bone.

Alpha emitters in the body can be detected by in vivo measurements

only if 1;he disintegration is accompanied by gamma photons or if there are

daughter products which decay by gamma - or hard beta - emission. Ura-

nium 238 and 235 can be detected down to levels of MPBB (5). The pro-

minent features of the uranium gamma spectrum are lines at 186 Kev and

about 90 Kev. The 186 Kev line is from U 235 (0, 8 y/a). The 90 Kev line

is due to Th 231, the daughter of U 235, and to Th 234, the daughter of

U 238. The 186 Kev line can be used to determine the U 235 content and

the relative magnitude of the 90 Kevli'neis an approximate indicator oJ t̂he

isotopic concentration level. A coarse calibration using an uranium so-

lution in the chest of the phantom (Fig. 15) has shown that the lowest lung

content of natural uranium that can be detected v/ith our. equipment in a

one hour measurement is about 40 mg. The ICRP 195& recommended MPL

of natural uranium in the lungs is 25, 6 mg.

SI.

Neutron dosimetry of humans by in vivo gamma spectrometric measure-

ments of the sodium - 24 content in the body has proved to be a useful tech-

nique. The human body contains natural, nonradioactive sodium - 23 at an

average amount of 105 grams. When the body is exposed to neutrons, neutron

capture yields Na 24, which emits 1, 38 and 2, 75 Me v gamma quanta. The

2, 75 Mev quanta can be measured without interference from the natural

activity. In order to calculate the neutron dose from the sodium activity

the energy spectrum of the neutrons must be known and also the activation

of the sodium in the body per incident neutron as a function of the neutron

energy (18). One author (6) has reported that the limit of detection with a

9" x 4" NaJ crystal is 12, 5 millirad if the measurement is made within

fifteen hours after the exposure.

6. Human Body Counter. No. 2

During the more than two years that we have utilized the body counter

it has definitely been proved that this type of instrument is a useful tool

to control exposure to internally assimiliated radioactive nuclides. It is

simple to establish that excessive doses have not acurred and in case of

contamination the nature of the radioactivity can be identified and the levels

of the specific isotopes can be determined directly.

At the new Research Centre of our Company at Studs vik a body counter

no. 2 will be built. It will be of the same type with a NaJ crystal and an iron

room. We intend to use a bigger crystal 8" x 4", so that the time per measure-

ment can be reduced from the 60 minutes at present to 15 minutes. The iron

room will be enlarged and have inside dimensions of 2 m x 2 m x 1, 8 rn in

order to provide more comfort for the subjects and also more space for

different detector arrangements. Fig. 16 shows the lay-out of the human

body counter localities.

Measurements of this type gives vast amounts data, which often have

to be treated in similar ways. The most common operations are subtraction

of the actual background, calculation of potassium and cesium contents,

•12.

applying corrections for the body constitution, checking certain energy bands

on,abnormal count rates etc. This invites the, use of automatic data pro-

cessing and we shall therefore in the new apparatus use a pulse height ana-

lyzer with read out on punched tape which is matched to our computer.

13,

References

1) ANDERSSON E C, SCHUCH R L, FISCHER W R and LANGHAM W LScience, _I_25, 1263 (1957)

2) ANDERSSON E C and LANGHAM W HScience, 131, 659 (I960)

3) ANDERSSON I ÖFOA-2 Report, A 2051-2097, Stockholm (1959)

4) BURCH P R J and SPIERS F WScience, _L20, 719 (1954)

5) COFIELD R EY-1250, Oak Ridge (1959)

6) COFIELD R EY-1283, Oak Ridge (1959)

7) LANGHAM W H and ANDERSSON E CHealth Physics, 2, 30 (1959)

8) MARTINSSON KAE-5, Stockholm (1959)

9) Me NEILL and GREEN R MCan J Phys. ; £7» 6 g3 (1959)

10) MILLER C E, MARINELLI L D. ROWLAND R E and ROSE J ENucleonics, _M (4), 40 (1956)

11) MILLER C E and MARINELLI L DScience, ^_24, 122 (1956)

12) MILLER C E and MARINELLI L DANL-5518, p 52, Argonne (1956)

13) MILLER C EANL-6104, p 78, Argcnne (i960)

14) PSRKINS R W and NIELSEN J MScience, J_295 94 (1959)

15) RUND O J and SAGILD UNature, 175, 774 (1955)

16) RUNDO JA/Conf. 15/P/1467, Geneva (1958)

17) SIEVERT R MStrahlentherapie ., 99, 185(1956)

14.

18) SNYDER W SPaper RB/55 presented at Symposium on Selected Topics in RadiationDosimetry, Vienna, June 7-11, I960

19) WOODWARD K T, CLAYPOOL H A and HARTGERING J BHearings before the Special Subcommittee on Radiation of the JointCommittee on Atomic EnergyPart 1, p 565 (1959)

IÖA and IN/EL

15.

Table I, K 42 counting-efficiency with different geometrical arrangements

BS

KE

ES

SB

Subj(

length

cm

187

178

179

164

2Ct

•Px:en•H©cr>

78

75

80

62

Averagee ffic iency

Average Yeff ic iency

Averagedeviation

Averageerror

Maximumerror

Averagephoto-fraction

Subject seated in chairx)

Crystal at position 1 '

Total

Eff.

0.119

0.124

0.119

0.116

0.120

0.667

Dev.

0.001

0.004

0.001

0.004

0.0025

2.0 %

4 %

Photopeak

Eff.

0.0186

0.0198

0.0196

0.0184

0.0191

0.106

Dev,

0.0005

0.0007

0.0005

0.0007

0.0006

3.1 %

3.7 %

Photopeak

fraction

15,6

16.0

16.5

15,9

15.9

x)Crystal at position 2

Total

Eff,

0.166

0,168

0.151

0.135

0.155

Dov»

0.011

0.013

0.004

0.020

0.012

7.7 %

)XO /o

1

Photopeak

Eff.

0,0262

0,0265

0,0229

0,02'?

0.0242

•

Dev.

0o0020J

0.0023

0.0013

0.0030

0.-.0016

6,6 %

12.4 %

Photopeak

fraction

15.8

15» 8

15.2

15.7

15.6

x) The centre of the crystal is in position 1,40 cm and in position

2,36 cm from the seat and back of 'the chair.

Tab le I l s Cs 137/K r a t i o In Htxc/g K •

in people. [Number of measurements]

U S-(7,

England

Canada (

Germany

SWEDEN

11)'

(16,19)

9,19)

(7,19)

1955

10

1956 }

41 [196]'

i'957

44 [311]

34 [16]

1958

34

39

?i-

32

[noo]

[7]

[30]

,[2]

1959

57

73

74

73

[183]

[2]::_

[15]

[27]

1960

55 [lO]

EHT unit

Potentio-meter

Amplifier

Cathodefollower

Puhe ampli-tude analyzer

Sealer

Figure 1. Layout of the Human Body Counter andblock diagram of its instrumentation.

Connexions to pre-amplifierand high voltage

Mu-metal mag-netic shield

Stainless steeldetector shield

5" photomultiplierEMI 9530

Inner standfor multiplier

4" x 4" Nal (Tl)-crystal

Shock shield

Fig, 2. The scintillation detector for HBC no. i .

103-

Background 33OOOcph

1460 keV

•o

CO

«> 1 0 2

ex.

101 .

Net spectrum

18600cph

—i—

1500500 1000Energy, keV

Fig. 3. Spectrum of an unexposed human

and background 100 - 1750 Kev.

10*1

10 3 '

•ocC}

ca

LO4

OJ

_cQ.

. O

10

1460

ThC"+RaC 2100-2200

ThC" 2620

T «

1000T r-

2000 3000Energy, keV

Fig. 4 Background 200 - 3500 Kev.

Head

Neck

Cross section Vertical length

ellipse 190x140 200

circle 0130

Over-arm circle 0100

Upper-body ellipse 200 x 300

Leg circle 0120

Material: 4 mm polythene

100

300

400

Lower partthe body

Forearm

Thigh

of ellipse 200 X

circle 0 76

circle 0150

360 200

450

400

400

Figure 5. Phantom with its inner dimensions

103

"O

cQQ

LO 1<p

Q .

O .

10 _l I I L _L

500

E'igure 6-

1000Energy» keV

o- 10~°v C K-40 in phantom

-B

1500

10 C K-42 in man

103

XI

c•00

1 102LOCNs_0>Qu

-CO .u

~lr~i• i

-

i

-

\ \

\

' It

\

VV

ttti

11

/••»

1\t\11t\1

Li

\

1

1

1t

1 1 1

r\i \/

//Iii

j

1 1 » f

\\

11

1

500Energy, keV

Figure 7. —

1000 1500

-—— 140 g K in phantom

.»._ 10"8 C Cs-137 in phantom

10 3 -

Phantorn spectrum

.Human spectrum

cva

CD

<N 1 0 2 .

Q-

Q-U

10 -

500

40K-1460 keV

1000 1500Energy, keV

B. Soectr;; from phautoni and human body with the same

amount of Cs 137 and K.

500 1000Energy, keV

Figure 9> Human-•y-spectrum

1500

douched and with standard clothes, 18600 cph (60 - 1750 KeV)

not douched and with normal clothes 22100 cph(60 - 1750 KeV)

Fi.^. 10. The oands used to determine K, Cs and bremsstrahlung.

10-

» s - « -

1 . 6 -57"

t 4-

2-

n

Average Zt 20

r = 13 %

n= 27

1 2

Fig. i i a. Frequency distribution of potassiumweight ratio in men.

3 gK/kg

10-

a

t 6-03cr .a> 4 -

2 -

n» 27

Average 73<r = 28 %

0 20 40 ;60 i80 100 120 140 Cs/gK

Fig. l ib . Frequency distribution of cesium potassiumratio in men. (May 1959)

301000 1500

'Energy, keV

Fig. 12. V-spectrum from a subject contam. with

7 mp.c Zn 65.

Energy, keV

Fig. 13. V-spectrum Irom a ma» contaminated by 36 hrBr 82 and 250 d Zn 65.

In the lower curve is his normal +Zn 65 spectrum subtracted.

3000-1

Normal human spectrumphantom measured 1 pc 90Sr + 90Y

-Normal human spectrum

200 300 400 500Energy, keV

600 700 800

Fig. 14. Spectrum of bremsstrahlung from Sr 90 + Y 90

3000-i

2000-

"O

c:ca

-isi

OJQ.

U

1000-

Normal human spectrum+ 200 mg nat. uranium in phantom

Normal human spectrum

200 mg nat. uranium in phantom

1000

Energy, keV

Fig. 15. Spectrum of natural uranium in a solution in the

chest of the phantom.

Patient way:\

^'Sluice*

Undressing-room

Material andpersonal way:\

Sluice!

"v_€hanging-room!

1 nstrument-roomi

Fig. 16. Lay-out of r aons connected with HB C no. Z.

LIST OF AVAILABLE AE-REPORTSAdditional copies available at the library of

AB ATOMENERGIStockholm • Sweden

A E N o

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Title

Calculation of the geometric buckling for reactorsof various shapes.

The variation of the reactivity with the number,diameter and length of the control rods in a heavywater natural uranium reactor.

Comparison of filter papers and an electrostaticprecipitator for measurements on radioactive aero-sols.

A slowing-down problem.

Absolute measurements with a 4«-counter. (2ndrev. ed)

Monte Carlo calculations of neutron thermaliza-tion in a heterogeneous system.

Metallurgical viewpoints on the brittleness of be-ryllium.

Swedish research on aluminium reactor technology

Equipment for thermal neutron flux measurementsin Reactor R2.

Cross sections and neutron yields for U1M, U145

and Pu"9 at 2200 m/sec.

Geometric buckling measurements using the pulsedneutron source method.

Absorption and flux density measurements in aniron plug in Rl.

GARLIC, a shielding program for GAmma Radi-ation from Line- and Cylinder-sources.

On the spherical harmonic expansion of theneutron angular distribution function.

The Dancoff correction in various geometries

Radioactive nuclides formed by irradiation of thenatural elements with thermal neutrons.

The resonance integral of gold

Sources of gamma radiation in a reactor core.

Optimisation of gas-cooled reactors with the aidof mathematical computers.

The fast fission effect in a cylindrical fuel element.

The temperature coefficient of the resonance inte-gral for uranium metal and oxide.

Definition of the diffusion constant in one-grouptheory.

A study of some temperature effects on the pho-nons in aluminium by use of cold neutrons.

The effect of a diagonal control rod in a cylindricalreactor.

RESEARCH ADMINISTRATION: A selected andannotated bibliogtaphy of recent literature..

Some general requirements for irradiation experi-

Metallograpbic Study of the Isothermal Transfor-mation of Beta Phase in Zircaloy-2.

Structure investigations of some beryllium materials.

An Emergency Dosimeter for Neutrons.

The Multigroup Neutron Diffusion Equations ASpace Dimension.

Amhof

N. G. Sjöstrand

H. McCnnck

R. Wiener

I. Carlvtk, B. Pershagen

Ktntin Martinsson

T. Högberg

G. Lagerberg

B. Forsen

E. Johansson, T. Nilsson,5. Claesson

N. G. SjöstrandJ. S. Story

N. G. Sjöstrand, J. Medms,T. Nilsson

R. Nilsson, J. Brann

M. Roos

S. Dipker,

I. Carlvik, B. Pershagen

K. Ekberg

K. Jirlovt, E. Johansson

M. Roos

P. H. Margin

1. Carlvik, B. Pershagen

P. Blomberg, E. Hellstrand,S. Hörner

N. G. Sjöstrand

K-E. Larsson, U. Dahlborg,S. Holmryd

T. Nilsson, N. G. Sjöstrand

E. Rhenman, S. Svensson

H. P. Myers, R. Skjoldebrand

G. Östberg

I. Fåldt, G. Lagerberg

J. Braun, R. Nilsson

S. Linde

Printedin

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Hgts

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24

4

14

20

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14

13

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Sw. er.

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4

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Affärslryck, Stockholm 1960