heavy water organic cooled reactor

43
AI-.CE-45 METALS, CERAMICS, AND MATERIALS HEAVY WATER ORGANIC COOLED REACTOR PRELIMINARY ANNULAR UC FUEL CASTING DEVELOPMENT Contract: AT(38-1)-430 FOR THE U.S. ATOMIC ENERGY COMMISSION By N. H. KATZ LEGAL NOTICE This report was prepared as an account of Government sponsored work Neither the United States, nor the Commission, nor any person acting on behalf of the Commibbion A Makes any warranty or representation, expressed or implied, with respect to the accu racy, completeness, or usefulness of the information contained m this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights, or B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed m this report As used m the above, "person acting on behalf of the Commission" includes any em- ployee or contractor of liie Commission, or employee of such contractor, to the extent that ' such employee or contractor of the Commission, or employee of such contractor prepares disseminates, or provides access to, any information pursuant to his emplojment or contract with the Commission, or his employment with such contractor iAR 1 5 1969 ATOMICS INTERNATIONAL-COMBUSTION ENGINEERING A Joint Venture for Heavy Water Organic Cooled Reactors WSTRIEJ-ION O DOCUMENT IS UNLIMITED •'^i

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Page 1: HEAVY WATER ORGANIC COOLED REACTOR

AI-.CE-45 METALS, CERAMICS,

AND MATERIALS

HEAVY WATER ORGANIC COOLED REACTOR

PRELIMINARY

ANNULAR UC FUEL CASTING

DEVELOPMENT

Contract: AT(38-1)-430

FOR THE U.S. ATOMIC ENERGY COMMISSION

By

N. H. KATZ

L E G A L N O T I C E This report was prepared as an account of Government sponsored work Neither the United States, nor the Commission, nor any person acting on behalf of the Commibbion

A Makes any warranty or representation, expressed or implied, with respect to the accu racy, completeness, or usefulness of the information contained m this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights, or

B. Assumes any liabilities with respect to the use of, or for damages resulting from the use of any information, apparatus, method, or process disclosed m this report

As used m the above, "person acting on behalf of the Commission" includes any em­ployee or contractor of liie Commission, or employee of such contractor, to the extent that

' such employee or contractor of the Commission, or employee of such contractor prepares disseminates, or provides access to, any information pursuant to his emplojment or contract with the Commission, or his employment with such contractor

iAR 1 5 1969

ATOMICS INTERNATIONAL-COMBUSTION ENGINEERING A Joint Venture for Heavy Water Organic Cooled Reactors

W S T R I E J - I O N O DOCUMENT IS UNLIMITED •' i

Page 2: HEAVY WATER ORGANIC COOLED REACTOR

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency Thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

Page 3: HEAVY WATER ORGANIC COOLED REACTOR

DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document.

Page 4: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

ACKNOWLEDGMENT

The author wishes to thank R. N. Beam for his unceasing

a s s i s t ance and suggest ions , which w e r e a major contribution

toward solving a difficult casting problem. "

1.1

Page 5: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-

CONTENTS

Page

Abs t rac t 6

I. Introduction. 7

II. Exper imenta l 9

A. Mold Gating Design 9

B. Cast ing Exper iments — Single-Cavity Molds 9

1. 3/4 in. OD (1/4 in. wall) by 3 in. Long 9

2. Scaleup to L a r g e r D iame te r s 13

a. Cast ing Nominal 2.000-in. OD Hollow Cyl inders . . 13

b . Casting Nominal 3.500-in. OD Hollow Cylinders . . . . . . . . 17

3. Analysis of Hollow UC Cylinders Cast in Single-Cavity Molds 19

a. Composit ion 19

b . Internal Defects 19

c. Dimensions 19

d. Metal lography 21

C. Cast ing Exper iments — Multiple-Cavity Molds 21

III. Discuss ion of Resul ts 28

A. Feas ib i l i ty Demonstra t ion . 28

B. Major P rob lem Areas 28

IV. Conclusions. 32

References 33

TABLES

1. Dimiensions of Single-Cavity Graphite Molds and As-Cas t Cyl inders . 18

2. Diamet r ica l Shrinkage of Cast Annular UC Fuel (Measured vs Calculated) 18

3

Page 6: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

FIGURES

Page

Graphite Mold Used for Single-Cavity Casting of 3 /4- in . OD Annular UC Fuel ( -1 /4 in. wall)

a. Components 10

D« x\.ssemDx6ci . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l u

As-Cas t Hollow UC Cyl inders , Nominal 3/4 in. OD (1/4 in. wall) by 3 in. Long

a. Casting F r o m Heat SC-4 12

b. Cast ings F r o m Heats SC-4, - 5 , and -6 12

Graphite Mold Used for Single-Cavity Casting of 2.000-in. OD Annular UC Fuel ( -1 /4 in. wall)

b. Par t i a l ly Assembled (Both cores positioned within base plate) . . . 14

C r a c k - F r e e , A s - C a s t , Hollow Cyl inders of Nomiinal 2.000 in. OD and 1/4-in. Wall Thickness 15 A s - C a s t , Hollow Cyl inders of Nominal 3.5 00 in. OD and 1/4-in. Wall Thickness

a. F r o m Heat SC-12, Showing Diametr ica l ly Opposed V^ X^ 3 . C- JXO « c * * B a « « » a a « a a c a « * a s o a « * * a a a * * a e a « « t * a X O

b . C r a c k - F r e e Cyl inders , 1-1/2 in. Long, Typical of Heats O^fc** •" X J t o " " X ( • e a a « a a e s a a * a a a * a a « « a « a a « * a a « s a a a a a X O

As-Cas t , Hollow Cyl inders , 3/4 to 3.500 in. OD and 1/4 in. Wall (Note excellent surface finish on ID of 2.000 and 3.500 in. OD C y X X X l d C T ' S / a a a « a « a a a a « a * e « « » e * « e a e a a a a a a a a a e a a a « a a l O

Compar ison of Measured and Calculated Diamet r ica l Shrinkage of A s - C a s t Annular UC Fuel , as a Function of Diameter (Values taken from Table 2) 20

Typical T r a n s v e r s e Mic ros t ruc tu r e of As -Cas t , Hollow, Stoichiometric UC Cylinder of Nominal 2.000 in. OD and 1/4-in. Wall Thickness

a. Adjacent to ID 22

iJ« \^ siiX L 6 X ^ * * a a a a a a * a e « a * a a a s a a a » « c * « a * « a a a * a « a a a a Lji CJ

C « . / x C L J 3 . C 6 X 1 X t O V . / X . / • • a a « a « a a a a * a a a a * a a e a a a a s a a a a « a e * a L4 dt

#

4

Page 7: HEAVY WATER ORGANIC COOLED REACTOR

FIGURES

Typical T r a n s v e r s e Mic ros t ruc tu re of As -Cas t , Hollow, Hyper s to ichiometr ic (~4.92 to 5.02 wt % C) UC Cylinder of Nominal 3.500 in. OD and 1/4-in. Wall Thickness

a. Adjacent to ID . .

b . Center

c . Adjacent to OD

Multiple-Cavity Graphite Mold, Assembled for Use in Skull-Cast T i l t -Pour Furnace (Note conical graphite dis t r ibutor and flat d i s t r ibu tor plate la te r added to top of mold)

Graphite Mold for Mult iple-Cavity Casting of 3-1/2 in. OD Annular UC Fuel Cylinders

a. Components

b. Assembled

C r a c k - F r e e Hollow UC Cylinder , 3 -1 /2 in. OD (1/4 in, wall) by 6 in. Long, Cast in Multiple-Cavity Mold (Note smooth, defect-free ID surface , as compared to porosity of OD C>U.X X e t c . w / a a s a a « a a « * a a » » e e * a a a e « a a e a a e a a a a i a e

5

Page 8: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

ABSTRACT

An exploratory casting p r o g r a m was conducted to de te rmine

the feasibili ty of cast ing hyper s toichiometr ic uranium carbide in

the shape of r i n g s , as fuel for application in advanced Heavy

Water Organic Cooled Reactor (HWOCR) annular e lement des igns .

Unique mold gating sys t ems w e r e developed for both s ingle- and

mult iple-cavi ty molds . This resul ted in the successful a r c ca s t ­

ing of uranium carbide fuel r ings and hollow cyl inders of var ious

outside d i a m e t e r s , ranging from 3/4 to 3.5 in. , all having a

1/4-in. v/all th ickness , and lengths up to 6 in.

The major problem a r e a s per t inent to the development of a r e ­

liable mul t ip le-cavi ty skull casting p roces s for annular uran ium

carbide fuel have been isolated and analyzed. However, additional

work is r equ i red to reso lve existing problem a r e a s and to develop

advanced technology for a l a r g e - s c a l e , economical , mul t ip le -

concent r ic - r ing cast ing p roces s for the advanced HWOCR concepts .

6

Page 9: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

I. INTRODUCTION

An exploratory casting p rog ram was initiated to de termine the feasibility of

and problem a r e a s assoc ia ted with the development of a p rocess tor fabricating

r ing-shaped hypers to ich iomet r ic UC fuel for application in advanced Heavy Water

Organic Cooled Reactor (HWOCR) annular e lement design concepts .

F r o m the standpoint of r eac to r design, the annular concept offers a number

of advantages over the rod -c lu s t e r e lement , chief among them being design

flexibility and more c r o s s - s e c t i o n a l fuel a rea per element . With r ega rd to

flexibility, each fuel ring and coolant channel may be var ied in th ickness , and

the number of fuel r ings may be var ied over a wide range . This is not feasible

for the r o d - c l u s t e r e lement , where the use of more than two or three kinds of

rods is imprac t i ca l , and the number of rods per element is l imited to bundles

which fit symmet r i ca l ly into a round p rocess tube (e .g . , 7, 19, 37, and 61 rods ) .

The design flexibility of the annular e lement may be used to advantage to obtain

a "balanced" design — one in which the coolant velocity in each coolant annulus

in the element is the s a m e , and in which the maximum cladding tempera ture on

both sides of each fuel ring is the s ame . This approach can elimiinate excess

coolant, and should resu l t in improved neutron economy.

In addition, the annular e lement may be designed with more c ross - sec t iona l

fuel a rea per e lement than a rod -c lu s t e r element . In the rod-c lus te r element ,

as the fuel a r ea is i nc reased , the maximum cladding t empera tu re of the cen t ra l

rods d e c r e a s e s . As the fuel a r e a of the annular element is increased , the cool­

ant a rea in the center of the element may be dec reased , maintaining the limiting

surface t e m p e r a t u r e on each fuel r ing. Thus, the advantage of the annular e l e ­

ment over the rod -c lu s t e r e lement i nc r ea se s with fuel a r ea . Increased fuel a r e a

r e su l t s in a r eac to r capital cost savings , by reducing the number of p r e s su re

tubes requ i red in the c o r e .

F r o m the standpoint of fabricat ion, the state of the a r t regarding casting of

annular UC fuel is v i r tual ly nonexistent. Several p re l iminary , unpublished,

s m a l l - s c a l e exper imen t s , conducted at Atomics International in previous y e a r s ,

indicated that UC r ings , pa r t i cu la r ly l a rge d iameter r ings , were difficult to

fabr ica te , due p r imar i ly to the high coefficient of the rmal expansion and the

inherent b r i t t l eness of UC.

7

Page 10: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

The p r i m a r y intent of the w^ork descr ibed in this r epo r t w^as to initiate d e ­

velopment of techniques for the cast ing of annular UC fuel of sound s t ruc tu re

and with controlled dimensional var ia t ions . This r epo r t p r e sen t s the s ta tus of

the initial phase of the development of annular UC fuel for use in concentr ic

fuel e lements .

Page 11: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

II. EXPERIMENTAL

A. MOLD GATING DESIGN

The reference procedure at AI for a r c casting UC fuel in the form of solid

rods cons is t s basical ly of t i l t pouring molten UC into mul t i -cavi ty graphite

(ATJ grade) mo lds . The molten UC is allowed to solidify without r e s t r a in t ,

usually resul t ing in uncracked r o d s . The casting of UC into an annular shaped

fuel is considerably more complicated, because it r equ i re s the use of a mold

c o r e . The s imples t approach ( i . e . , for metal fuel) is usually to use a solid

c o r e . However, e a r l i e r (unpublished) exper imenta l efforts at AI had indicated

that the use of solid graphite co re s always produced catas t rophic cracking of UC

upon solidification, due to the l a rge differential expansion between UC and graph­

i te . Thus , so l id -co re casting was not pursued, and all efforts w e r e initially d i ­

rec ted tov^ard designing a s ingle-cas t ing nriold gating sys tem which would give

uncracked r i ngs .

The use of a thin-wall graphi te core was selected as a f i rs t approach, on the

theory that the co re should be s t rong enough to r e s t r a i n the molten UC during

solidification; but its s t rength should be sufficiently low that it would crush with

contract ion of the UC during cooling, and would not impose hoop s t r e s s e s on the

ring that would be la rge enough to f rac ture the casting in tension.

Several thin-wall c o r e s , having a 0.010-in. wall thickness and a 1/4 in. OD,

were fabricated fronn ATJ grade graphi te , and were designed for casting UC

tubes , 3/4 in. OD (1/4 in. wall) by 3 in. long. The cores (one is shown in F ig­

ure la) were fabricated from solid graphi te blocks by f i r s t machining an over­

sized OD, boring the ID to exact d imens ions , followed by a f inished-dimension

cut on the OD. This technique was used throughout the p rogram, and was the

only method available without resor t ing to development of special tooling and

fabricat ion methods .

B. CASTING EXPERIMENTS - SINGLE-CAVITY MOLDS

1. 3/4 in. OD (1/4 in. wall) by 3 in. Long

The f i r s t s e r i e s of a rc casting exper iments used a single-cavity graphite

mold shown in F igure la and the thin-wall co re (0.010 in. thick) descr ibed

9

Page 12: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

'ft

TOP SUPPORT AND CENTERING PLATE FOR HOLLOW CORE

SOLID GRAPHITE ROD

(HEAT SINK)

0.010-in. WALL HOLLOW CORE

BOTTOM PLUG AND SUPPORT FOR HOLLOW CORE

UNC a. C o m p o n e n t s

7 6 8 0 - 5 1 1 5 4

rj^

% ^ ^ ' •

b . A s s e m b l e d

UNC 7680-51155

F i g u r e 1. G r a p h i t e Mold Used for S i n g l e - C a v i t y C a s t i n g of 3 / 4 - i n . OD A n n u l a r

UC F u e l ( - 1 / 4 in . wa l l )

10

Page 13: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

previously , a s sembled as shown in F igure lb. The f i rs t s ingle-cavi ty exper i ­

ment (SC-1) consis ted of melting a charge of 1.5 kg of hypers to ichiometr ic UC

(-4.9 wt% C) in an a tmosphe re of purified argon at 23 in. Hg, and pouring at

2500"C (via the mold d is t r ibutor ) into the mold cavity between the OD of the

hollow c o r e and the ID of the mold. Instead of a hollow cylinder , a solid slug

was formed, which was at t r ibuted to par t ia l dissolution of the 0.010-in. thick

core wall by the molten UC before solidification was complete . A duplicate ex­

per iment (SC-2) produced identical r e s u l t s . It was concluded that the heat t r a n s ­

fe r red to the thin-wall co re was not being diss ipated rapidly enough to prevent

dissolution of the c o r e . The next exper iment (SC-3) was s imi la r to the previous

two, with the exception that a solid graphite rod (Figure la) was added to the

mold (inside the thin-wall core ) , loosely contacting the core wall along its ent i re

length. The casting produced with this mold was a hollow cyl inder , 3/4 in. OD

(-1/4 in. "wall) by 3 in. long, which had severe ly cracked throughout during cool­

ing. The inabili ty of the UC to c ru sh the thin-wall core was a d i rec t resu l t of

having insufficient c l ea rance between the graphite rod and the co re ; in effect,

this produced a solid graphi te core which could not be crushed. However, the

thin-wall co re did not d issolve .

The mold was modified again, to overcome this so l id-core effect; the radial

c lea rance between thin-wall core ID and the graphite rod (heat sink) was in­

c reased froin vir tual ly ze ro to -0.004 in. The melting and casting of UC was

ca r r i ed out (Heat SC-4), using the same pa r ame te r s as in previous hea t s . This

unique approach produced a hollow, uncracked annular cast ing, 3 in. long by

0.7 10 in. OD by 0.244 in. ID (shown in F igure 2a). Examination of the cas t ing-

mold assembly , after r emova l from the furnace, confirmed the theory that the

UC would c rush the thin graphi te shell during cooling, and not build up sufficient

hoop s t r e s s to c r a c k the cas t ing . The casting was easily removed from the mold,

leaving all components of the mold intact (with the exception of the thin-wall co re ,

pa r t s of which adhered to the ID of the cast ing) . The a s - c a s t surface finish of

the cyl inder was coraparable to that obtained for cast UC r o d s . Two additional

heats (SC-5 and -6) were made , and produced duplicate r e s u l t s . The cast ings

from these three exper iments a r e shown in Figure 2b. A radiographic examina­

tion of the hollow cyl inders revealed only slight porosi ty adjacent to the top of

the cas t ing , much l e s s than that normal ly encountered in a solid slug.

11

Page 14: HEAVY WATER ORGANIC COOLED REACTOR

A I - C E - 4 5

.. C a s t i n g F r o m Hea t S C - 4

UNC 7 6 6 0 - 5 1 1 9

UNC 7 6 6 0 - 5 1 1 1 b . C a s t i n g s F r o m H e a t s S C - 4 , - 5 , and -6

F i g u r e 2. A s - C a s t Hol low UC C y l i n d e r s , N o m i n a l 3 / 4 in . OD ( 1 / 4 in . wa l l ) by 3 in . Long

12

Page 15: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

An impor tant considerat ion (real ized ear ly in this program) is that, with the

present mold design, the mold cavity may be completely filled; but it must be

prevented from being overfilled and forming a header , which is the usual p ro ­

cedure in cast ing r o d s . With this design, the formation of a header would be

followed by the miolten UC solidifying and contracting around the solid graphite

d is t r ibutor plate [which a l so se rves as a centering support for the thin-walled

core and solid rod (heat s ink ) ] , resul t ing in severely cracked cas t ings .

2. Scaleup to L a r g e r Diamete r s

The developinent effort in casting annular UC fuel was continued, with empha­

s is on expanding the p rocess to cas t considerably l a rge r d iamete rs than 0.750 in.

specifically 2.000 and 3.500 in. OD with a 1/4-in. wall th ickness .

New mold designs w e r e p repa red , using the design for the 3/4-in. OD cylinder

as a b a s i s , and taking into considera t ion the total inside d iametra l contraction

expected for 2.000- and 3.500-in. OD cyl inders of UC (from liquid at 2500°C to

ambient t e m p e r a t u r e ) , w^hich w e r e calculated to be -0.042 and -0.080 in. r e ­

spectively. Adding c lea rance for the hollow core wall th ickness , a mold for

casting a 2.000-in. OD cylinder v/as designed with a 0.065 in. c l ea rance , and a

mold for the 3.500-in. OD cylinder was designed with a 0.115 in. c lea rance .

a. Cast ing Nominal 2.000-in. OD Hollow Cylinders

In actual fabricat ion of the 2.000-in. d iameter mold, a machining e r r o r r e ­

sulted in only a 0,015 in. c l e a r ance . One heat (SC-7) was made, using this mold.

The resul t ing UC cylinder was 3 in. long and had two wide c r a c k s , d iametr ica l ly

opposed, extending the length of the cyl inder . Subsequent molds were fabricated

with the requ i red 0.042-in. c lea rance between the d iameter of the solid graphite

inse r t (heat sink) and the ID of the hollow c o r e , or a total of 0.065 in. between

the OD of the hollow core and the d iameter of the solid graphite inse r t . The

mold components for the 2.000-in. d iamete r mold assembly a r e shown in F ig ­

u re 3a. P a r t i a l and complete a s sembl i e s of the components a r e shown in F ig­

u res 3b and 3c respec t ive ly . The next four heats (SC-8 to -11) produced three

sound, c r ack - f r ee cyl inders having a mean OD = 1.936 in. and ID = 1.492 in., by

3 in. long. The three cyl inders a r e shown in F igure 4. The fourth cylinder was

found to have developed a c rack which extended part ial ly along the length. This

occur red as a r esu l t of an overfill of UC around the graphite distr ibution plate;

13

Page 16: HEAVY WATER ORGANIC COOLED REACTOR

A I - C E - 4 5

a. C o m p o n e n t s

f OLD BASE PLATE

UNC

MOLD BODY HOLLOW CORE

SOLID CORE (HEAT SINK)

DISTRIBUTOR AND CENTERING

PLATE FOR BOTH CORES

7680-51156

b . P a r t i a l l y A s ­s e m b l e d (Both

c o r e s p o s i t i o n e d w i th in b a s e p la te )

UNC 7680-51157

c . A s s e m b l e d

St

^

F i g u r e 3 . G r a p h i t e Mold Used for Single-Cav i ty C a s t i n g of 2 . 0 0 0 - i n . OD A n n u l a r

UC F u e l ( - 1 / 4 in . wa l l )

UNC 7680 -51153

14

Page 17: HEAVY WATER ORGANIC COOLED REACTOR

Ol

UNC F i g u r e 4. C r a c k - F r e e , A s - C a s t , Hollow C y l i n d e r s of N o m i n a l

2 .000 m . OD and 1 /4- in . Wal l T h i c k n e s s

7 6 6 0 - 5 1 1 5

> I—I

1

O w I

Page 18: HEAVY WATER ORGANIC COOLED REACTOR

A I - C E - 4 5

UNC 7 6 6 0 - 5 1 2 1 a. F r o m Hea t S C - 1 2 , Showing D i a m e t r i c a l l y Opposed C r a c k s

UNC 7660-5125 b . C r a c k - F r e e C y l i n d e r , 1-1/2 in . L o n g , T y p i c a l of Hea t s SC-13 to -17

F i g u r e 5, A s - C a s t , Hol low C y l i n d e r s of N o m i n a l 3.500 in. OD and 1 /4 - in . Wall T h i c k n e s s

NOMINAL 3 4 in. OD

NOMINAL 2.000 in. OD

NOMINAL 3.50C in. OD

UNC 7660-5123 F i g u r e 6. A s - C a s t , Hol low C y l i n d e r s , 3 / 4 to 3.500 in . OD and 1/4 in . Wal l (Note e x c e l l e n t s u r f a c e f i n i sh on ID of

2 .000 and 3.500 in. OD c y l i n d e r s )

16

Page 19: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

upon solidification, the overfill c racked and propagated into the cylinder. This

further ennphasized the need to avoid pouring a header or r i s e r above the cylin­

d e r s . The surface finish of the cy l inders v^as representa t ive of that usually en­

countered in cast ing UC s lugs . A radiographic analysis was made to deterinine

the extent of p r i m a r y pipe formation and other internal casting defects within

the cyl inder wal l . Only one cylinder exhibited a smal l p r imary pipe formation

which extended 1/4 in. dov/n from the top of the cyl inder . The other cylinders

did not exhibit any defects .

b . Casting Nominal 3.500-in. OD Hollow Cylinders

The apparent success in casting the 2.000-in. OD cylinder led to the fabr ica­

tion of a graphite mold and gating sys tem for casting the 3.500 in. OD cylinder,

based upon the design used for the 2.000 in. cyl inder . The fabricated molds

were s imi la r to the components and assembly shown in Figure 3. Molds were

fabricated with a total c lea rance of 0.080 in. between the d iameter of the solid

graphite i n s e r t (heat sink) and the ID of the hollow c o r e , or a total of 0,115 in,

between the OD of the hollow core and the d iameter of the solid graphite inse r t .

The length of the nnold cavity w^as l imited to 1-3/4 in. by the smal l UC melt

capacity of the furnace and the re la t ively l a rge d iameter of the cylinder.

The f i r s t a t tempt (SC-12) at cast ing a 3.500-in. OD cylinder of hypers to ichi ­

ometr ic UC resu l ted in an overfill of molten ma te r i a l around the distr ibution

p la te . Subsequent shr inkage generated c r a c k s , d iametr ica l ly opposed, which

propagated into the cylinder (Figure 5a). The next five heats (SC-13 to -17)

produced one additional c racked cyl inder , due to overfill , and foxur sound, c r ack -

free cyl inders with an average OD = 3.391 in. , an ID = 2.936 in, , and a length

which ranged between 1-1/2 and 1-3/4 in. A typical a s - c a s t cylinder is shown

in Figure 5b. The outside surface condition of this cylinder was represen ta t ive

of that found for a s - c a s t UC slugs . However, the inside surface , after removal

of the hollow co re in se r t , general ly exhibited considerably l e s s roughness and

fewer surface defects . A good view of the inside surface of the nominal 3.500-

in. OD cylinder is shown in Figure 6, which displays cast ings of different

d i a m e t e r s .

One problem encountered after removal of the UC cylinder from the mold

was delayed cracking , which occur red severa l hours l a t e r , but pr ior to removal

17

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AI-CE-45

TABLE 1 DIMENSIONS OF SINGLE-CAVITY GRAPHITE MOLDS

AND AS-CAST CYLINDERS

Mold D i m e n s i o n s (in.)

C a s t i n g D i m e n s i o n s (in.)

Sh r inkage (AD) (in.)

Nomina l 3 / 4 in . OD by 1/4 in . ID by 3 in. Long UC C a s t i n g

Oute r m o l d tube OD 1.000 ID 0.750

Inne r s h e l l c o r e OD 0.270 Solid c o r e i n s e r t OD 0.240

OD

ID

Top 0.724 Bo t tom 0.720

Top 0.267 Bo t tom 0.266

OD

ID

Top B o t t o m

Top Bo t tom

Nomina l 2.000 in. OD by 1.5 in . ID by 3 in. Long UC C a s t i n g

Outer m o l d tube OD ID

I n n e r she l l c o r e OD ID

2.375 2.000

1.520 1.500

OD

ID

Top Bot tom

Top Bo t tom

1.937 1.935

1.490 1.488

OD

ID

Top B o t t o m

Top Bo t tom

-0.026 -0.030

-0.003 -0.004

-0.063 -0.065

-0 .030 -0 .032

Solid c o r e i n s e r t OD 1.430

Nomina l 3.500 in. OD by 3 in . ID by 1-1/2 in . Long UC C a s t i n g

Oute r m o l d tube O D ID

Inne r she l l c o r e OD I D

Solid c o r e i n s e r t O D

4.000 3.500

3.000 2.970

2.855

OD

ID

T o p Bot tom

T o p Bot tom

3.395 3.390

2.930 2.930

O D

ID

T o p Bot tom

T o p Bot tom

-0 .105 -0 .110

-0 .070 -0 .070

TABLE 2

DIAMETRICAL SHRINKAGE OF CAST ANNULAR UC FUEL

(Measured jvs Calculated

Nomina l A s - C a s t

C y l i n d e r OD (in.)

3 /4

2.000

3.500

D i a m e t r i c a l Shr inkage (in.)

M e a s u r e d (Avg)

OD

0.028

0.064

0.107

ID

0.004

0.031

0.070

C a l c u l a t e d

OD

0.022

0.060

0.104

I D

0.007

0.045

0.089

Page 21: HEAVY WATER ORGANIC COOLED REACTOR

AI-CE-45

of the hollow core i n se r t . This was at tr ibuted to a combination of fac tors , in­

cluding res idua l hoop s t r e s s e s and further contract ion of the casting around the

graphi te . Maintaining a compres s ive s t r e s s on the cylinder c i rcumference until

the graphi te in se r t could be removed by machining appeared to be the immediate

solution to this p rob lem. S t ress rel ieving at elevated t empera tu res has been

considered as an a l t e rna te solution for future investigation.

3. Analysis of Hollow UC Cylinders Cast in Single-Cavity Molds

a. Composit ion

Both carbon and oxygen analyses w e r e made on each cylinder. The carbon

contents , which w e r e made to vary for the purpose of achieving either stoichi­

ometr ic or hypers to ich iomet r ic UC, were in the range of 4.72 to 5.02 wt % C.

The oxygen content, obtained by vacuum fusion, ranged from 50 to 310 ppm,

with the average being 13 8 ppm. The var ia t ion in carbon content did not appear

to affect the quality of the cast ings produced, in t e r m s of defects or c r a c k s .

b . Internal Defects

A radiographic ana lys i s was made to de termine the extent of p r imary pipe

formiation and other in ternal casting defects within the cylinder wall . The analy­

s is revea led a slight amount of porosi ty in one 3/4- in . OD cylinder, and a thin

p r imary pipe in one 2-in. OD cas t ing, extending 3/16 in. down from the top. All

other cyl inders examined were free of internal pipe formation. The number of

defects found were only a smal l fract ion of the total usually encountered in UC

s lugs .

c. Dimensions

A dimensional analys is was made on all a s - c a s t cy l inders , to determine the

degree of shrinkage as a function of the nominal casting OD. Major emphasis

was placed upon determining the total d iamet r ica l change of the cy l inders , with

the dimensions of the respec t ive graphite molds in which they were cas t serving

as r e fe rence . The dimensions of the single-cavity graphite mold conaponents,

and the cast ings produced from them, a r e given in Table 1. The mean d iamet r i ­

cal shrinkage ( A D ) was measu red , and is given in Table 2, where it is compared

to calculated shr inkage based upon the following assumpt ions:

19

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AI-CE-45

Q

-0.110

-0.100

-0.090

-0.080

-0.070

-0.060

-0.050

-0.040

-0.030

-0.020

-0.010

NOMINAL CASTING OD (in.

10-21-66 UNC 7680-51238

Figure 7. Compar ison of Measured and Calculated Diametr ica l Shrinkage of A s - C a s t Annular UC Fuel , as a Function of

Diameter (Values taken from Table 2)

20

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A I - C E - 4 5

1) M e a n coef f i c i en t of t h e r m a l e x p a n s i o n ( a , ) for UC = 16.0 i n . / i n . - ° C x 10

b e t w e e n 2550°C ( e s t i m a t e d s u p e r h e a t t e m p e r a t u r e ) and 2450°C ( e s t i m a t e d

s o l i d i f i c a t i o n t e m p e r a t u r e for U C , ), T h i s va lue w a s ob ta ined by e x t r a p o ­

l a t i n g t h e r m a l e x p a n s i o n da t a for h y p e r s t o i c h i o m e t r i c UC g iven in N A A - S R -

8538.^^^

2) M e a n coef f ic ien t of t h e r m a l e x p a n s i o n (a ^) for U C , , f r o m 2450 to

2 0 ° C , S 12.3 i n , / i n , - ° C x 10"^.^^^

3) M o l t e n UC c o n t r a c t s u n i f o r m l y in a l l d i r e c t i o n s .

A f u r t h e r c o m p a r i s o n of m e a s u r e d and c a l c u l a t e d d i a m e t r i c a l s h r i n k a g e i s

shown in F i g u r e 7. It m u s t be no ted tha t t he c a l c u l a t e d A D i n c l u d e s only s o l i d -

s t a t e c o n t r a c t i o n , and i s e x p e c t e d to differ f r o m the m e a s u r e d A D by an a m o u n t

w h i c h wou ld inc lude the c o n t r a c t i o n f r o m :

1) L i q u i d a t s u p e r h e a t e d cond i t i on to l iqu id a t m e l t i n g poin t of UC

2) L i q u i d - t o - s o l i d p h a s e change

3) E r r o r s in m e a s u r e m e n t of c y l i n d e r d i a m e t e r s .

d. M e t a l l o g r a p h y

A m e t a l l o g r a p h i c a n a l y s i s w a s p e r f o r m e d on the n o m i n a l 2.000 and 3,500 in.

OD c y l i n d e r s , t o a s c e r t a i n m i c r o s t r u c t u r a l c h a r a c t e r i s t i c s and h o m o g e n e i t y .

The r e s u l t s i n d i c a t e a u n i f o r m m i c r o s t r u c t u r e t r a n s v e r s e l y a c r o s s the w a l l

t h i c k n e s s , as shown in F i g u r e 8 for s t o i c h i o m e t r i c UC and in F i g u r e 9 for h y p e r ­

s t o i c h i o m e t r i c UC, The a n a l y s e s w e r e l i m i t e d to the 2,000 and 3,600 in. OD

c y l i n d e r s ; s i n c e t h e y r e p r e s e n t e d the m o s t diff icul t d i a m e t e r s to c a s t , and on t h e

c o n t e n t i o n t h a t , if n o n u n i f o r m p r o p e r t i e s w e r e p r e s e n t , they would m o s t l i ke ly

show up in the l a r g e r d i a m e t e r c a s t i n g s .

C . CASTING E X P E R I M E N T S - M U L T I P L E - C A V I T Y MOLDS

T h e i n i t i a l d e v e l o p m e n t w o r k d e s c r i b e d in S e c t i o n B w a s c a r r i e d out u s i n g

s i n g l e - c a v i t y g r a p h i t e m o l d s , w i t h c a s t i n g p e r f o r m e d in a n e x p e r i m e n t a l s i z e

( -3000 a inp) a r c - m e l t i n g f u r n a c e c a p a b l e of pour ing a m a x i m u m of 1.2 kg of

m o l t e n U C .

21

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A I - C E - 4 5

a . Ad jacen t to ID

A/-

Z5CX

UNC 6237-23-2

b . C e n t e r -- X '

(AT, 0.004 in.

250 X

UNC 6237-23-4

\

UNC

C .0C4 in .

250 X

c . Ad jacen t to OD

6237-23-6

F i g u r e 8, T y p i c a l T r a n s v e r s e M i c r o s t r u c t u r e of A s - C a s t , Hol low, S t o i c h i o m e t r i c UC C y l i n d e r of N o m i n a l 2.000 in. OD and

1 /4 - in , Wal l T h i c k n e s s

22

Page 25: HEAVY WATER ORGANIC COOLED REACTOR

A I - C E - 4 5

'i^i:KV^^'7

a. Adjacen t to ID

UNC 6237-36-2

b . C e n t e r

UNC 6 2 3 7 - 3 5 - 4

c . Adjacent to OD

UNC 6 2 3 7 - 3 6 - 6

F i g u r e 9. T y p i c a l T r a n s v e r s e M i c r o s t r u c t u r e of A s - C a s t , Hol low, H y p e r s t o i c h i o m e t r i c ( -4 .92 to 5.02 wt % C) UC C y l i n d e r of N o m i ­

nal 3.500 in. OD and 1 /4- in , Wal l T h i c k n e s s

23

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A I - C E - 4 5

UNC 7660-4003 F i g u r e 10. M u l t i p l e - C a v i t y G r a p h i t e Mold , A s s e m b l e d for

Use in S k u l l - C a s t T i l t - P o u r F u r n a c e (Note c o n i c a l g r a p h i t e d i s t r i b u t o r and f lat d i s t r i b u t o r

p l a t e l a t e r a d d e d to top of m o l d )

24

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AI-CE-45

The next phase of the annular fuel cast ing p rogram was directed toward

scaleup of both the length of the 3 -1 /2 - in . OD cylinder (from 1-1/2 to ~6.00 in,)

and the quantity of cyl inders cas t per heat . This entailed designing a completely

new mold gating sys tem, for use in conjunction with a large (10,000 amp) skull-

cas t t i l t -pour furnace. A mult iple-cavi ty mold, for casting five cyl inders per

heat , was designed and fabricated. The initial design for each individual mold

cavity was s imi la r to the design for the s ingle-cavi ty mold used in casting the

nominal 3 -1 /2 - in , OD r ings . An assembled mult iple-cavi ty mold is shown in

Figure 10.

The f i r s t a t tempt at cast ing five cyl inders simultaneously was Heat M C - 1 ,

which consis ted of skull melting a total charge of ~4 kg of hypers toichiometr ic

UC (~5.0 wt % C) and pouring at an es t imated t empera tu re of 2650°C. (The

skul l -cast ing furnace is es t imated to produce molten UC, superheated to at

leas t 100°C higher than the smal l a rc -mel t ing furnaces used in the s ingle-

cylinder casting exper iments . ) An analys is of the resu l t s of this heat indicated

that the hollow core inse r t s had burned through, result ing in the formation of

shor t thick-walled cyl inders which cracked severely upon cooling. A second

heat , MC-2 , produced a lmost identical r e s u l t s , with the exception that one

1- 1/2-in. long by 3 - 1/2-in. OD cylinder was found to be c rack f ree .

P r io r to making any additional h e a t s , the design of the mult iple-cavity mold

was modified. A l a rge , conical graphi te dis t r ibutor (shown in Figure 10) was

added to the mold, to provide a m o r e laminar flow and to di rect the flow of UC

into the cav i t i e s . A second modification was a flat dis t r ibutor plate (shown in

Figure 10), added to the miold to chill the molten UC before it entered the cavi­

t i e s . The next th ree hea ts (MC-3, -4 , and -5) resul ted in a total of three p a r ­

t ial ly filled mold cavi t ies ; the r ema inde r were unfilled, due to excessive chilling

and premiature solidification of the molten UC. As the distr ibutor plate appeared

to provide too much chilling and r e s t r i c t i on to the flow of UC, it was removed

for the next heat (MC-7), and only the conical dis tr ibutor was left in the mold.

The r e su l t s w e r e s imi la r to the initial heats ( i . e . , hol low-core burn through,

producing thick-walled cyl inders which cracked severely upon solidification and

cooling to ambient t e m p e r a t u r e s ) . The major problem was the development of

a method for achieving the c o r r e c t amount of heat dissipat ion. The mold design,

in which the solid core (heat sink) was separa ted from the hollow co re , had been

25

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A I - C E - 4 5

QilARTEE-SECTiONED SOUP CORE

hOLlOf CORE

UNC 7 6 6 0 - 4 0 0 2 a . C o m p o n e n t s

UNC 7 6 6 0 - 4 0 0 1 b . A s s e m b l e d

F i g u r e 11 . G r a p h i t e Mold for M u l t i p l e - C a v i t y C a s t i n g of 3 - 1 / 2 in. OD A n n u l a r UC F u e l C y l i n d e r s

F i g u r e 12. C r a c k - F r e e Hol low UC C y l i n d e r , 3 - 1 / 2 in . OD ( 1 / 4 in. wa l l ) by 6 in . L o n g ,

C a s t in M u l t i p l e - C a v i t y Mold (Note s m o o t h , d e f e c t - f r e e ID s u r f a c e ,

a s c o m p a r e d to p o r o s i t y of OD s u r f a c e )

UNC 7660-51137

26

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AI-CE-45

successful for s m a l l - s c a l e experi inents using s ingle-cavi ty molds . In this

application, the pour t empe ra tu r e was appreciably lower than in the mult iple-

casting p r o c e s s ; and the heat diss ipat ion was be t te r , since there was more

mold m a s s per cas t ing. However, the design had to be modified for multiple

cast ing, to provide rapid diss ipat ion of heat from the hollow core and prevent

burn through. The design was changed to bring the solid inse r t (heat sink) in

d i rec t contact with the hollow c o r e . The inse r t was fabricated in four sect ions ,

and two graphi te spacer spr ings (at top and bottom of the mold) kept these sec ­

tions apar t and in contact with the c o r e . The springs allowed the sections to

contract during solidification and cooling of the UC cyl inders without generating

sufficient hoop s t r e s s to c r ack the cy l inders . The mold components and the

assembled individual mold a r e shown in Figure 11. Five of these individual

molds w e r e assembled in a mold housing, as shown in Figure 10, for multiple

cast ing.

The ne'w mold design was evaluated in Heat MG-8, which was s imi la r in most

r e spec t s to the previous mul t ip le-cas t ing heats (MC-1 to -7). The heat resul ted

in two complete c r ack - f r ee cy l inders , having a nominal 3-1/2 in. OD (1/4 in.

wall thickness) and 6 in. length, as shown in Figure 12. The remaining three

cavit ies produced incomplete or cracked cyl inders , p r imar i ly due to overfill or

leakage around the center plug. The two c rack- f ree cyl inders produced were

s imi la r in gra in s t ruc ture to the cyl inders produced in the ea r l i e r s ingle-cavi ty

casting expe r imen t s . The inside surfaces of the cyl inders were very smooth,

and comparab le to the inside surfaces present on the 3-1 /2- in . OD single-cavity

cy l inders . On the other hand, the outside surfaces exhibited more porosity than

had been encountered previously . This was at tr ibuted to incomplete outgassing

of the heavy-wall graphite mold, against which the OD of the cylinder was

formed, as compared to m o r e complete outgassing of the thin-wall hollow core

which was used to form the inside sur face .

Fu r the r exper imenta l work in the developinent of economic p rocesses for the

casting of annular UC fuel cyl inders should include additional studies of mold

gating and dis t r ibut ion s y s t e m s .

27

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AI-CE-45

III. DISCUSSION OF RESULTS

A. FEASIBILITY DEMONSTRATION

The initial objective of the f i r s t phase in the development of a p roces s for

casting annular UC fuel (specifically, feasibil i ty demonstrat ion) has been

achieved. The s e r i e s of s ingle-cavi ty exper iments has shown that UC r ings , or

hollow cyl inders of var ious d i a m e t e r s , can be cast without c r a c k s and with a s -

cast surfaces comparable to those obtained on re fe rence p r o c e s s UC s lugs .

Problem a r e a s which r equ i r e further investigation a r e outlined in the following

section.

B. MAJOR PROBLEM AREAS

The mold gating sys tem design, which is the major var iab le in the p rocess

(as r ega rds i ts capabil i ty of producing minimum-defec t , c r a c k - f r e e cy l inders ) ,

was found to be l e s s complex for the s ingle-cavi ty mold design than for the

mul t ip le-cavi ty mold. The need for adequate heat diss ipat ion became m o r e c r i t i ­

cal with the higher pouring t empe ra tu r e of molten UC and the d e c r e a s e in mold

volume per casting which w^ere experienced in mul t ip le-cavi ty cas t ing. The

graphite spring spacer design used for mul t iple-cavi ty skull cast ing appears to

provide the rapid diss ipat ion of heat requi red ; however, considerably more ex­

per imenta l data is needed to es tabl ish the level of re l iabi l i ty of this design. The

mold-gating sys tem for mult iple casting of concentr ic cyl inders is expected to be

even more complex, but i s a lso expected to substantial ly i n c r e a s e p rocess

efficiency.

The following problem a r e a s in casting and mold-gating design, which a r e

basical ly inseparab le , a t t r ibuted to the fai lure to form and /o r maintain complete ,

c rack- f ree cy l inders :

1) Hollow core burn through

2) Uncontrolled cyl inder contract ion during solidification

3) Overfill format ion of header ( r i se r )

4) Residual hoop s t r e s s e s .

28

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AI-CE-45

Burn through, as indicated e a r l i e r in the r epo r t , occurred at the levels of

superheat experienced in both the sma l l - s ca l e single-cavity a r c casting and in

the mul t ip le-cavi ty skull casting exper imen t s . The solution to this problem was

ei ther to dec rea se the superheat or to provide bet ter heat dissipation from the

hollow c o r e . Decreasing the superheat was imprac t ica l , as this would invar i ­

ably resu l t in incomplete mold fill and severe cold shu ts . Thus, it was n e c e s ­

s a r y to modify the mold design to improve the heat dissipation from the hollow

c o r e . The graphite spring spacer design appears to have solved this problem

for mul t ip le-cavi ty cast ing, by t r ans fe r r ing heat from the UC to the quar te red

heat sink inside the hollow c o r e . Since acceptable 3-1 /2- in . OD (1/4 in. wall)

cyl inders w e r e cas t by this technique, it is now considered feasible to cas t any

hollow cylinder up to 3-1 /2 in. OD (and, projecting beyond th is , to at leas t

4 -1 /2 in. OD) with the same (-1/4 in.) wall th ickness . Additional experimental

work is requ i red to de te rmine whether the technique is suitable for casting cyl­

inders with a wall thickness appreciably g rea te r or less than the 1/4 in. used in

Phase I development.

Most of the cylinder cracking was caused by inadequate c lea rance allowance

for total cylinder shrinkage (liquid to solid s ta te + the rma l contraction) around

both the hoUow^ core and the heat sink. For the s ingle-cavi ty design, this p rob­

lem was solved by providing mold component c lea rances which matched the total

actual shr inkage experienced with a given cylinder d iameter . The same approach

was at tempted for xnultiple-cavity cast ing, but was unsuccessful , because skull

casting produced higher UC superheat which caused burn through of the thin-wall

hollow co re mold component. The sp r ing - space r design produced c rack- f ree

cy l inders ; but re l iabi l i ty has not been establ ished, due to insufficient exper i ­

mental data . However, the sp r ing - space r design technique v/ill be the reference

p rocess for cast ing annular UC fuel, unless it is proved to be inadequate or

unre l iab le .

Another major problem a rea which has not been completely resolved is mold

overfi l l , which occurs when either the amount of molten UC poured exceeds the

volume of the cavi t ies or the c o r r e c t mass of UC is unevenly distr ibuted to the

cav i t i es , A conical graphite d i s t r ibu tor , central ly located, was used to reduce

turbulence and equalize dis tr ibut ion. This approach would work if the s t rea in of

molten UC could be directed and maintained immediately above the d is t r ibutor .

29

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AI-CE-45

However, the present pouring technique was establ ished for skull casting slugs

with a header ( r i s e r ) , and it would have to be modified. In future development,

considerable effort w^ill be needed, to de te rmine an optimum gating sys t em.

Cont ra ry to the usual p rac t i ce of casting UC slugs with a r i s e r , annular UC

shapes may not r equ i r e a r i s e r to the same extent, if at a l l . This was indicated

by radiographic ana lyses , which revealed very thin p r i m a r y pipe adjacent to the

top of the cast ing. The la rge center m a s s , usually present in s lugs , is e l imi ­

nated in annular fuel cas t ings , thereby el iminating the region w^here severe

shrinkage and pipe formation often occur . An added advantage of casting without

a r i s e r is that considerably l e s s charge m a t e r i a l is requ i red per heat , or using

the same quantity of UC can produce more cas t ings . This is expected to inc rease

the casting efficiency and reduce operating and product cos t s ; because , in the

re ference slug cast ing p r o c e s s , 30 to 50% of the total weight of UC poured is

header ( r i s e r ) , and the balance is in the form of s lugs .

Another possible cause of cylinder cracking is the res idual hoop s t r e s s e s

within the cyl inder , formed by nonuniform solidification and contract ion during

cooling from the liquid s ta te to ambient t e m p e r a t u r e s . This cooling is con­

t rol led by the r a t e of heat diss ipat ion f rom the OD and ID of the cast ing, which

is a function of the mold design. The problem has not been reso lved , in t e r m s

of finding the optimum mold design; however , a proposed solution is to ma in ­

tain the cylinder in compress ion , d iamet r ica l ly , until a s t r e s s - r e l i e v i n g t r e a t ­

ment can be applied.

The economic feasibil i ty of production casting annular UC fuel has not been

the subject of this r epo r t , and cannot be adequately a s s e s s e d until addit ional

development is performed in the following a r e a s :

1) Continued mul t ip le-cavi ty casting development, until a re l iable p rocess

is established

2) Scaleup of the mul t ip le-cavi ty casting p r o c e s s , and modification of

existing mold designs to include concentr ic cylinder cast ing. A p rogram

would be requ i red to de te rmine the feasibility of concentr ic cyl inder casting

and i ts eventual sca leup.

3) Development of a sui table , economical p rocess for surface finishing

annular fuel to mee t HWOCR design r e q u i r e m e n t s . The l a rge surface a r ea

30

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to m a s s ra t io r equ i re s an economical machining p r o c e s s , and also a good

a s - c a s t surface finish which will minimize total stock removal . This p rob­

lem a r ea v/ould be grea t ly minimized in a fuel element design which used a

liquid meta l bond between fuel and cladding.

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IV. CONCLUSIONS

The feasibility of cast ing UC into r ing-shaped fuel, for use in advanced

annular element des igns , has been demonst ra ted . The casting p r o c e s s developed

incorpora tes a unique mold gating sy s t em, used in conjunction-with conventional

melting p a r a m e t e r s es tabl ished for prepar ing molten UC for casting UC s lugs .

The maximum OD of 3-1 /2 in. , wall thickness of 1/4 in. , and length of 6 in.

attained during this init ial phase of development were by design, and a r e not

considered to be l imiting d imensions .

While bench-sca le a r c - ca s t i ng and product ion-or iented skul l -cas t ing furnaces

have been used successful ly to cas t annular fuel in s ingle-cavi ty and mul t ip le -

cavity molds , respec t ive ly , a cons iderably g r e a t e r development effort will be

needed to es tabl i sh a high re l iabi l i ty level for the l a t t e r .

The major causes of cylinder cracking have been isolated and analyzed. It

is believed that they can be reso lved , for mul t ip le-cyl inder (and probably

mul t ip le -concent r ic -cy l inder ) cas t ing , through the development of adequate

mold gating s y s t e m s .

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REFERENCES

1. Pr iva te Communicat ion, H. Rood, Atomics International , Canoga Pa rk , Calif. (1965)

2. R. Mendez-Pena losa , "Thermal Expansion of Uranium Monocarb ide ," NAA-SR-8538 (September 30, 1963)

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DISTRIBUTION

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Advanced Planning & Resea rch Southern Se rv ices , Inc.

600 North 18th Street Bi rmingham, Alabama 3520 3

Attention: Mr. Ruble A. Thomas , Manager

Atomic Energy of Canada, Limited:

ASAEC Technical Representa t ive Whiteshell Branch, Chalk River Office U. S. Atomic Energy Commiss ion c /o Whiteshell Nuclear Resea rch

Es tabl i shment AECL Pinawa, Manitoba, Canada

Attention: Mr. H. J . Reynolds

USAEC Scientific Representa t ive Chalk River Liaison Office c /o Atomic Energy of Canada Limited Chalk River , Ontar io , Canada

Attention: Mr . Miller N. Hudson, J r .

Whiteshell Nuclear Resea rch Es tabl i shment

c /o Atomic Energy of Canada, Limited Pinawa, Manitoba, Canada

Attention: Dr . R. F . S. Rober tson

The Babcock and Wilcox Company Atomic Energy Division P . O . Box 1260 Lynchburg, Virginia 24505

Attention: Mr. W. M. Vannoy,

Carol inas Virginia Nuclear Power Assoc ia tes , Inc.

P a r r , South Carol ina 29066

Attention: Mr . H. T. Babb. Manager

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Communaute Europeenne De L 'Ene rg ie Atomique I sp ra Resea rch Center Casel la Pos ta le 1 I spra (Varese) Italy

Attention: Mr. Tauch 1

E. I. du Pont de Nemours and Company Explosives Depar tment Wilmington 98, Delaware 19898

Attention: Dr. D. F . Babcock, Direc tor 1 Reactor Engineering Section

E. I. du Pont de Nemours and Company Savannah River Laboratory^'^ Aiken, South Carol ina 29801

Attention: Dr. J . L. Crandal l 1 Mr . S. W. O 'Rear , Supv. 2 Technical Information Serv.

Mr. E. C. F i s s c /o Duke Power Company P . O . Box 2178 Char lot te , North Carol ina 28201 1

Massachuse t t s Insti tute of Technology 77 Massachuse t t s Avenue Room 24-109 Cambridge 39, Massachuse t t s 02139

Attention: Dr. Manson Benedict, Head 1 Dept. of Nuclear Engineering

Massachuse t t s Institute of Technology NW12-234 138 Albany Street Cambr idge , Massachuse t t s

Attention: Dr. E. A. Mason 1

Oak Ridge National Labora tory Union Carbide Corpora t ion AEC Operat ions P. O. Box X Oak Ridge, Tennessee 37831

Attention: Mr. D. A. Douglas 1 Mr. D. E. Ferguson 1 Mr. J . A. Lane (ORNL P . O . Box Y) 1 Dr. I. Spiewak 1

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Pacific Northwest Labora to ry P . O. Box 999 Richland, Washington 99352

Attention: Dr. J . J . Cadwell , Manager 1 Metal lurgy Depar tment

Puer to Rico Water Resources Authority Box 4267 San Juan, P u e r t o Rico

Attention: Dr. Modesto I r i a r t e , J r . 1 Sr. E lec t r ica l & Nuclear

Power Engineer

Rensse lae r Polytechnic Insti tute Troy, New York

Attention: Dr. P . B. Daitch 1 Dept. of Nuclear Science

and Engineering

Tennessee Valley Authori ty 303 Power Building Chattanooga, Tennessee 37401

Attention: Mr . C. H. Waugaman, Chief 1 Power R e s e a r c h Staff Mr . Harold L. Fa lkenber ry 1

U.S. Atomic Energy Commiss ion :

B r u s s e l s Office U.S. Mission to the European Communit ies APO, New York, New York 09667

Attention: Theodore J . l i t i s , 1 Acting Sr. USAEC Representa t ive

Chicago Operat ions Office 9800 South Cass Avenue Argonne, Illinois 60439

Attention: D. M. Gard ine r , Direc tor 2 Health &; Safety Division

Division of Compliance, Region 111 Suite 410 Oakbrook Profess iona l Building Oak Brook, Illinois 60523

Attention: Mr . H. D. Thornburg 1

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U. S. Atomic Energy Commiss ion (Continued):

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Oak Ridge Operat ions Office P . O. Box E Oak Ridge, Tennessee 37830

Attention: Mr. H. W. Behrman 1 Mr. R. L. Philippone 1

Richland Operat ions Office P . O. Box 550 Richland, Washington 99352

Attention: Mr. P . G. Hoisted, Direc tor 2 Resea rch & Development Div.

San F ranc i sco Operat ions Office (SAN) 2111 Bancroft Way Berkeley , California 94704

Attention: Mr. E. C. Shute, 1 Manager

Headquar t e r s , Washington, D . C . 20545:

Attention: Mr. R. M. F o r s s e l l , Chief 1 Advanced Development Branch Division of Naval Reac to r s

Division of Reactor Development & Technology:

Attention: Mr . Milton Shaw, Direc tor 1 Mr . R. W. Bean 1 Mr . M. Booth 1 Mr . J . W. Crawford, J r . 1 Mr . D. E. Erb 1 Mr. R. Fei t 1 Mr. A. Giambusso 1 Mr. P . A. Halpine 1 Mr . F . Kerze , J r . 1 Dr. J . A. L ieberman 1 Mr . W. M. McVey 1 Mr . B. T. Resnick 1 Mr . M. Rosen 1 Dr. E. E. Sinclair 1 Mr . F . R. Standerfer 1 Mr . A. N. Tardiff 2 Mr . K. A. Tr icket t 1 Mr. W. W. Ward 1 Mr . M. J . Whitman 1 Mr. W. A. Will iams 1 Dr. I. F . Zar tman 1

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RDT Site Offices:

A I - C E

RDT P r o g r a m Office (AI-CE) CPAO Canoga P a r k , California

Attention: Mr . J . V. Levy Manager , CPAO Mr. R. L. Morgan RDT Sr. Site Represen ta t ive

RDT Site Office P . O. Box 500 Windsor, Connecticut

Attention: Mr. A. J . Alexander RDT Sr. Site Represen ta t ive

RDT Site Office P . O. Box A Aiken, South Carol ina

Attention: Mr. J . H. Kruth RDT Site Represen ta t ive

United States Depar tment of the In ter ior Bonneville Power Adminis t ra t ion P . O. Box 3621 Por t land, Oregon 97208

Attention: Mr. E. C. S t a r r Consulting Engineer

Washington Public Power Supply System P . O. Box 166 130 Vista Way Kennewick, Washington

Attention: Mr . Owen W. Hurd, Managing Di rec tor

Westinghouse Elec t r ic Corpora t ion Atomic Power Depar tment P . O. Box 355 Pi t t sburgh 30, Pennsylvania 15230

Attention: Mr. S. Bartnoff, CVTR Pro j ec t Manager

Mr . Hood Worthington Devon Apar tments , No. 1512 2401 Pennsylvania Avenue Wilmington, Delaware 19806

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Atomics Internat ional P . O . Box 309 Canoga P a r k , California 91304 S. O. Arneson D/782 COOl R. Balent D/716 C002 G. D. Calkins D/745 COOl E. M. Chandler D/782 COOl J. C. Cochran D/784 COOl D. J . Cockeram D/731 C002 H. M. Diekamp D/797 C002 J. F . Erben D/799 C002 J. Falcon D/716 C002 J. J. F l ahe r ty D/797 C002 ^. C. Fulton D/710 C002 S. Golan D/793 C002 R. B . Gordon D/782 C002 J. R. Hume D/721 C002 R. T. Keen D/741 C004 G. Koris (Patent Office) D/896 C002 J. R. Lewis D/782 COOl J. E. Mahlmeis te r D/793 C002 W. E. Pa rk in s D/740 C002 T. G. P a r k e r D/782 COOl D. Saxe D/797 C002 S. Siegel D/793 C002 C. S t a r r ,, D/797 C002 B. J . Thomas D/782 Canada

*Atomics Internat ional Representa t ive at Cliaik River , Canada

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Combustion Engineering, Inc. Nuclear Division P . O . Box 500 Windsor, Connecticut 06095

C. Andrea 1 F . Bevilacqua 1 W. P . Bigler 1 H. C ahn 1 W. P . Chernock 1 A. W. Cope 1 J. R. Dietr ich 1 J. S. Greacen 1 R. S. Harding 1 H. V. Lichtenberger 1 E . H. Luther (Patent Office) 1 D. McLaughlin 1 H. Oslick 1 B. J . Selig 2 S. H. Shippenberg 2 P . Santoro 1 W. Taylor 1 J. C. Tobin , 1 R. P . Varnes* 1 S. Visner 1 J. M. West 1 R. H, Young 1 W, H. Zinn 1 CE HWOCR Fi le (B, Basu) 5 CEND F i l e , W. Simon 1

i HPO Representa t ive at Combustion Engineering. Use CE mailing add re s s .

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A I - C E

HWOCR P r o g r a m Office c/ P C

V L . M D W D K B D J . C B R S. W

w R M P H F C D C R H W H]

o A t o m i c s I n t e r n a t i o n a l O.

a.nog

E. E .

. G. P .

. S. G r S. L . A.

Box 309 a P a r k , C a l i f o r n i a 91304

A d l e r A n d e r s o n A n d r e w s Gary ' ' ' F l i n n

af H e l m Hoffman H u b e r

J a c o b s o n J o n e s Katz W. Mi

. A.

. B .

Keaten""" ne r

M u l l e r M u r r a y

Q u a n t o c k . K.

F . I. M. L . S. A. H.

S a n d e r s Shaw

S t a r r S t e r n S t o r r s T h o m p s o n T r i l l i n g V o l l m e r

V o n S t e i g e r . B . Wol fe*** PO C e n t r a l F i l e

:«HPO R e p r e s e n t a t i v e a t P i n a w a , C a n a d a . I'HPO R e p r e s e n t a t i v e a t H a l d e n , N o r w a y . i'HPO R e p r e s e n t a t i v e a t Doug las P o i n t , C a n a d a .

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