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ORNL-

366

9

FREPflEWTION OF k CESIUM

( 3 7 C ~ )

BOROSILICATE GLlSS

POWER SOURCE

C .

L. O t t i n g e r ,

E.

E . P i e r c e , and R. W.

Schaich

Isotopes Division

APRIL 1965

OAK

RIDGE

NATIONAL

JABOLUTORY

Oak

Ridge,

Tennessee

operated by

UNION

CARBIDE

CORPORATION

f o r the

U. S. ATOMIC EW3GY CONMISSION

3 4 4 5 b 0548240



Page

. . . . . . . . . . . . . . . . . . . . . . . . . .

1

os tmct

. . . . . . . . . . . . . . . . . . . . . . . . 1

ntroduct ion

2

hemical

Processing . . . . . . . . . . . . . . . . . . . .

Source Fabrication

P e l l e t i z a t i o n

. . . . . . . . . . . . . . . . . . . . . 4

. . . . . . . . . . . . . . . . . . . . .

4

Encapsulation

. . . . . . . . . . . . . . . . . . . . .

5

Assembly and Measurements

. . . . . . . . . . . . . . .

5

References . . . . . . . . . . . . . . . . . . . . . . . . . 13

Appendix.. . . . . . . . . . . . . . . . . . . . . . . . . 14



C . 5;. Ot t inger

E .

14

Pierce

R ,

bJ.

Schaich

37

A

cesium

(

CS) ‘boros i l i ca te sass powr source wii;’t.i 125

watt:;

tl-ierrrml

output was prepared

a t

-the

Isotopes

Development Center, O a k Ricl.ge National h b o r a t o r y

( O R N I L )

.

Techniques

for

the

p r e p r a t i o n of

‘the

u e l matei-Tal.,

i t s

casking

i n t o t h e p ro pe r

foi-11,

and the

fabrication

of

-the

f inal source capsules were developed,

This

paper descr ibes

t he chemical. proc essin g, fuel. pre pa rat ion , source

enxapsu-

l a t i o n ,

heal;

output measurements,

capsule l e ak - r a t e

d e t e r -

minutions, and measurervents on

t h e l o a d e d

skipping cask.

INTRODUCTION

I n 1961

a

program was initiated a t t h e ORNL Isotopes Development Center

t o

develop

techniques for the preparakion

of

a 1-25-mtt

( t h c m a l )

137Cs power

source fo r use i n an

m6 e r w a

C I ~ J ~ J ~ ~ ~ E I ~ ~ ~ O T ~he prP fe r red f u e l Por~ri

would

contain

ti?? 137Cs

i n

a glass v i t h

the h ighes t p rac t ica l power dens i ty

arid

a l o w l e ach

r a t e

i n

sea.

water.

Fused cesium ( l S 7 C s ) a luminos i l i ca te w a s cons iaered as a S O U T C ~mate r i a l

s ince 2 ha6 been shown t o have low s o l u b i l i t y i n most

aqueous

systcms and

t o

have a n eg l i g i b l e r e l e a s e of

137Cs

a t elevated temperntures . l

However,

t he 137Cs

concen t rat ion i n

cesium (137Cs)

aluminos i l icatc i s t o o low

(6-‘(

cur ies /g )

f o r

ap p l i c a ti o n s r eq u i r i n g

a

concentrated

he t

source;

s o

t h e

inves t iga t ion of 137~s source materials was extended t o the cesium

g ~ u s s e s

Culcir iation of cesium tetrapheny lboron i n

a i r

y i e l d s

C S ; ~ Q . B & ~ ~

be reacted with Si02 a t high temperature t o produce ces ium boros i l icate

glass .

A l l of

t h e

operations can be carried out by remote manipulator c e l l

operations.

borosilicate glass

was se lec ted

which

can

For t h i s r e as on

cesium

137Cs

.



2

as tlie

fml .

fomi

for

t h i s p r o j ec t , and t h e deve1,opmcnt

O S

a manufacturing

process

for t h i s m a t e r i a l

w a s

undertaken.

CHEMIC

AI,

PR

W E

NG

Prior

t o fu3.1-scale processing a t the Fission Products Development

Laboratory,

a

s e r i e s

of

experimental. crsi1.m gl.ass

preparations

was m. ie.

These included the preparat ion of i n ac t i v e

cesium

g lasses 'Graced

w l - t h

137Cs,

w i t h cesium contents ranging from 30-55 h ,;, and t h e p r ep am t i o n

o f

sma3 . l

amounts

of

i ~ ~ l yc-Live cesium (137~s)

orosilicate g3.a.::~

i n a

hot

cell.

On t'ne

bas is

of

t h e

resul.ts

o f these

experimental

runs, a

flow sheet (Fig. 1.) w a s developed Lo produce cesium

(

13'Cs) borosilica-t;z

g lass

v i t l i

a

cesium

content o f h.5-50wt ,;$.

one - t h i r d

of

khe atoms i.n fission-psodirc-f; cesium a r e 137Cs.

w a s as

rfoll.ows.

I t

w i l . l

be

r eca l led tha t abou t

The procedure

1.

Product-grad.e

fission-product . 3 7 C ~ @ l ( 3 3 cu r i e s

of

13"%sper

gram of c e s i m )

was

dissolved i n 0,L

M

a c e t i c

a,cLd

e

3 .

The

s l - u r y

vas

heated t o -(O C and sodium te t raphcnyl-

boron,

at

a

r a t l o

of

3.2 gi-iuns ~ i e r ;iTrm o f

cesium, vas

added.

4.

'Che system was cooled to 30°C; t h en t h e s l u r r y was

fil

ered

through

a

medium po ros ity - al.widim Ti l t c r

t'iiimblz

.

Nine preci.pi-tations we:^'^ necessary

I.n

ord.er

t o

yield.

s u f f i c i e i i t material t o

complete th e sourc e. The major opera t iona l problem thai; w a s encountered

dinring -the first

few

ruiis

was the tendency

of the

cesium tetraphenylboron

p r e c i p i t a t e

t o

s t i c k

t o

.Line

w d . 1 ~

f

the p r e c i p i t a t o r . Since

the

p r e c i p i t a t e

c o u l ~ I

ot be washed

o f f

t h e p r e c i p i t a t o r

m b l s

by normal water

spray flushing,

the

qiumtiitier, o f chemicals added had.

to

be

var ied

from

b a t c h

t o hatch

i n o%(ier

o mainta in

the desired

l3''Cs content

i n

t h e f i n a l

glass. Adjustment;

of the

ag i ta t i on and

tmshing

cycles r e s u l t zd

I.n an

operating procedure which T.WS used suc ces sful ly on the l a s t

four runs,

The



3

O R N L - D W G

64-7054

**

SE 0 2

0.1

N

ACETIC ACID

3-7 *

SODIUM TET RAP HEN YL BORON CsCl

PR EC PITAT ION

- 2.5

g / l i t e r CE S I UM

-v 8

g / l i t e r

SODIUM

T E T R A P H E N Y L BORON

*

BATCH SIZES: 2000 curies

TO

5 4 0 0 c u r i e s OF

137Cs

SiO, ADDITION S VARIED

TO PRODUCE AVERAGE

ACTIVITY CONCENTRATION

O F -15.5 curies/q IN FINAL

PRODUCT

**

FILTRATE

TO

WASTE TREATMENT

HOT-OFF-GAS TO

W A S TE TRE A TM E NT

HOT- OFF-GAS TO

W A S TE TRE A TM E NT

A S S A Y A ND

M E A S U R E M E N T S

Fig. 1. Cesiwti-137 Borosilicate Glass ProJec t - Flow Diagram



4

y i e l d

w a s

$$,

as

shown i n

Table

1,

w i t h

most of the

l o s s

i n equipment,

holdup

Table

1.

C e s i u m ( TCs)

boros il . i ca te p rcc ip i ta thxxs

-__-

.......

lll llalcine l...pre......c i p i t a t c

. ___....-

A ct i v i t y

Hatch S t a r t i n g 13'cs

Weight coincent

rat

i011 Total.

number ana lys i s , cur ies cur ies /g cur i es

1

2

5

6

9

Tota.ls

4

940

2,760

2,050

4,200

-I. ,500

2

000

4 '(00

5,200

35,750

_;,400

315.0

1.65

0

131

0

26 5

285

2

126

8

276

0

305 0

322,

2>2.92

13.5

15.0

15.0

15.0

15.0

1'7.0

17.0

17.0

l (.

4,250

1,960

2

-C'(O

I t ,

2 7980

2 ~ 6 0

4,630

3 h ,

3ho

S x

cesiun

sel ec te d batches of t he calci ned powder i n a Waring

Blend.or.

The C O I ~ ~ T J O S ~ ~ ~ S

w r e

loaded

i n t o

platinum cups;

-then th ey were

melted

individ .ual ly in s m a . l l

furnaces

a t l 2 O O 0 C f o r 3

hr.

l3'@s)

boros i l icate composi tes

were

prepared by blending

The s i x

melts weye weighed and

measurerl, and

t h e excess

platinum

was

removed by trimming with

a

shmp ki.if'e,

and mechanical los ses (ca lcu lat ed from veight-I.oss measurements) w a s

approxjimately 2,5013

cilri.es

(-10 ).

Ilea% out;put

ii1easvremenl;s were r i m

on

t h e Tndj.vid.ual rnclts

using

caLnrdrnet r ic tech niqu es developed by Posey e t

al_.s Yfle

d . a t a p e r t a h i n g t o Ynese

glass

r n e l k s are listed

i n

Table

2.

Since

the dens i ty va lues

are

based

on. m%.r;..imwa

dimensions, they are lower

than the t iwe physical.. ensity

of

t he gIass,

from

0.1.9

watts/m3,

t o

0.24

w a t t s / m L ,

i s

probably representa. t ive

for

a

series

o f cesi1m ( l S 7 C s ) horos il . i ca te g las ses

made

by -Lhz

technique

described.

The

'tokal 3?Cs

l o s s by v o l a b i l i t y

The

range of

power density,



5

Table 2.

Data on cesium ( l S 7 C s ) b o r o s i l i c a t e glass melts

Activi ty Heat Power

tk ig ht , Dens i ty , concentra t ion, cmtput den s i t y ,

Tota l

nutiber g l d cw i e

s / g

watts 137~s

w a t t s l a

c u r i e s

l 232.0

3.06

13.

I 14.41

0.19 3,200

2 316.0

3.24 14.8

20.58

0 . a 4,670

3 316.4

3.16

14.8

20.61

0.21

4,690

4

308.5

3.05

16.1

24.45

0.24 4,970

281.2

3.02 16.1

22*3 ,

0.24 4,550

b 2E . B

3.00

16.1 22.613

0.24

4,600

1

(40.9 125.10 26,680

Encapsulat ion

The s i x completed

cesium

(13-'Cs) b o r o s i l i c a t e glass melts (Fig. 2 ) were

loaded

i n t o two I l as te lloy inn er

capsl-iles.

The inner

capsules were

velded

rerfiotely

(p ig . 5)

under argon containing "KT t r a c e r .

~ a c ~ i

nner capstfie

was cleaned and Leak- tes ted f o r 85Ki,.

The inner capsules were inserbed

into

Xlsstelloy

oiiter

caps ules which were then welded remotely

under

wgon

with

KY

tr a ce r, The completed caps ules (Fig. 4) e r e l e a k - t e s t e d f o r

Kr,

then

cleaned. o an average smear count

of'<200

d/min f o r

a

sing1.e

smear over t h e en t i r e s u r f ace .

All of

t h e

l e a k

ra tes ,

determined

by thc

fi

tracer

niettioci.,

~iez le

elow

the

limit

of

detection

of

oW@t

n i ~ l y e a r

s ee

il-ppendizr

.

85

Assembly

and

Measmementc

@a3,1.0r.ime"Lic

mneasusements

on t h e cornpleted capsules showed 55.6 watts for

No.

1

and. 69,5 wa t t s

f o r No.

2.

Capsule

;No. 1 ms placed i n the bot tom of

t h c c a v i t y of

a

l?.O-in.-thick depleted

uranium

s h i e l d (Fig.

5 ) ,

and capsule

No.

2 w a s placed on t o p of capsule No. 1. The fr e e space above tile capsules

was approximately 1/8 in .

Thrce thermocouples were a t t a ch ed

t o

the shield--one on the bottom and

t w o

on oppos ik sides

of the

c y l i n d r i c a l p o r ti o n . A s shown i n Table 3, t h e

shrielcl

surface

temperature

was

f a i r l y uniform, w i t h

the

ternperatwe on t h e

boikom

surface running s l i g h t l y

l e s s

t h a n t h a t on t h e s i d e s .



I

,



9

Fig.

5.

Fuel Loading

of

Cesium (137Cs) Borosilicate Power Source



1

Table 3 .

Cesium (

137Cs

) borosi l icate power 'source

temperature measurements

May 28,

1962

my 29, 1@2*

oc

**

Time, Temp, Time, Temp,

c **

min Bottom Side Side

min

Bottom Sid e Sid e

0 80

88 83

72 80 80

1 5 81 85 85

15 io- 81

81

30 83

85

85

30 n

81 83

45

83

86 85

45 80 82

83

60 83

86

86

60

80 82 4.

*

**

These readings were taken with the shield resting on wooden blocks.

Ambient temperature w a s 30°C i n a l l cases.

The

uranium

s h i e l d w a s placed i n th e shipping cask (Fig. 6) nd allowed t o

remain overnight t o measure th e temperature under t ran sp ort condit ions.

Table 4 ives the temperatures thus measured; they showed that no tempera-

t ur e problems should be expected during tr an sp or t.

Table 4.

Cesium

(137Cs)

bo ro si l i ca te power source

shipping cask temperatures

L

Temp,

C

Time, Between ca sk Cask

hr Ambient and sh ie ld surfac e

____. _

I

0

1 7 - 5

16.25

18.25

30

27

27

28

72

72

72

71

30

41

41

41

The uranium shield

w a s

removed from the shipping cask and placed on

i t s

s id e

i n two wooden

V

blocks.

s h i e l d i n his a t t i t u d e .

The

r e s u l t s of these measurements and the

ca lcu la ted va lues

are

shown i n Table

5.

The agreement between the calcu-

lated and observed readings

w a s

s a t i s f a c t o r y

for

a

source

of

t h i s

s i z e

and

shape.

Radiation measurements were taken with the

-k

Smears

for

surface contamination were made on the uranium shield, the

inside of the shipping cask, and the

sur face

of

the shipping cask

just

p r i o r

t o lo adin g f o r shipment. In a l l cases the con taminat ion leve l was <20 d/min

alpha and <500 d/min beta-gamma.



i

11

PH O TO 577 7

Fig. 6 . Uranium

o s i l i c a t e Power Sou



12

Table 5.

Cesium (137Cs) bo ro si l i ca te power source

radiation measurements

Distance from

s h ie ld , em

Rad ia t ion ( s ide ) ,

mr/hr

Calculated Observed

Radiation (e nd ), mr/hr

Calculated Observed



1.

R. E .

Lewis, Reported i n

ORNL

progress repor ts and

s m n r i z e d i n

"Glasses"

Isotopes

and Radiation Technology,

1:81+

(Fa l l

1963).

2.

T,

C .

Quinby, Method

of

preparing radioact ive cesium

SQUTC~S,

U,

S.

Patent 3,114,716,

Dee. 17,

1963.

3 . J , C. Posey, T. A,

But le r ,

and P. S.

Baker, Hot c e l l calor im etry

f o r rout ine determination of thermal power genera ted by ki loc uri e

sources, Proceedings

_I_.

f the Tenth Conference on H o t $ahorator ies

and_ Equipment, Washington, D, C .

Nuclear Society.

1962 , pp. 2b5-m merican

4.

E. D. Arnold m d

B.

F. &skewitz, SDC - A sh ie ld in g des ign ca l cu -

la t ion code f o r f u e l h an dl in g f a c i l i t i e s

(A

smrking but incomplete

program

fo r

Vne

IBM-7090,

t o be publ i shed

as

ORNL-3041).



All

o f

Liir

s o u c c

capsules K J C ~ elded in a sealed weldel*

ixndcr

argon.

'Yh

following

procediux

was

used,

1.

2.

3 .

-L .

5.

6 .

> .

8 .

9.

The capsule, w i t h

a

p r p s s - f i t cap, w a s i n s e rt e d i n t o t h e

wclder, and the welder was sealed. The

capsule

cap was

scored t o permit transfer o f atmosphere betwpm the welder

&nil thc. capsule.

Tnc:

welder ~~8.smr:mtGed

nd

r e f i l l e d s i x t imes

hrii Ii

dry

argon. 'Then

3.1,

w a s pressur ized

t o

three atmospheres w%th

argon containing two

cimizs

of 8

The

cnpsifl-e w a s

welded.

The

capsule

was i-eninvccl f r 9 m

-the welder, aid t h e

wzld ~ i a s

i cispec

Led

visin_lly,

'The surface o f

Lhe capsule

was

cleaned.

The capsule w a s i n s e r t e d i n t o

.the

l e ak de t e c t o r

(a

sca led

cliamber having vaJ..vsd l i n e s to mcuim

ind argon supply and

cozmcctcd tiirou@ a valve .to 8,s). evacuated cow-Ling chmd,cr).

The

l e a k

de tec to r

was

evacuated

and

refilled

w i t h

d i ~ y rgon

foiir

tinies.

pres

su re .

Then I.-

as : f i l l e d

with argon

xL ztmospheric

The'

capsule

msallowed

t o

r c m i n i n

t h e l e a k

dc tcc to r for

fo u r

hours .

pass through any

leaks

i n the capsule and mix with t h e argon

i n the leak detector .

T;x mixed A r - 8sK r i n tile capsule cowl-d thus

The valve betveen M E 3.eizk de tec to r and the evacuated

cou i t ing cimbelg

t m b

opencil, and t h e system

was

al . lowd to

stabilize.

The counting chamber vas the a seaJ-ed, removed

from

the

system, &nil the

~ r s

counted,

The

fol lowing

csl.culations were ma& t o

d e t e m i n e I.eak

r a t e

:

Free volunz of

welder

12.2

l i t e r s

Free volume of

l e a k

dekector

1.08 l i k r s

VoJ-me of counting chamber

1.07

l i t e r s

Presswe o f welding gas ;i atm

8 5 ~ontent 2QOO rii

Efficiency of counter

( A r

+ R 5 ~ r

l ,

background count =

1(300

-

50 c/Klin



I

15

a)

Volume of'

welding gas

a t Z a t m

= 36,600

m l

b)

Concentrat ion

of

8*Kr i n

welding 88s

=

c )

D i s i n t eg r a t i o n rate

=

0.055 mc/m;l. x 2.22 x 110'

d / m i n * m c =

12*2

lo7 d/nin*ml.

d)

e )

count

r a t e a t l e f f i c i e n c y =

1 2 . 1 10

/ m i n * d

Tinerefore,

1

c/mrin

= 0.83 x 10 ' mL

f )

Since only 50$ of the l e ak d e t ec t o r g a s 1s

smiplcd,

1

c/min

= 1.66 x

niL

of welding gas

Since

the

back4,rounrl count c m v ar y by

120

c/niin

from nigh o l o w , any count ra te

of

1 20 c / i i ~ n

(equ iva len t t o 2.0 x io-* m~

of

gas)

represenbs

an uncer ta in leak.

count r a t e i s equ iva len t t o

a l e a k

r a t e

of

0.44

ml/year

under

the

cond.it ions described. Tine Limit of

detection may

be 1-educed

by increas ing the accmiu-

l a t i o n

time.

g )

For

a

4-hr accumula t ion , th i s

w h i c h

i s

t h e lowes t l eak rate de-tectable

i



t

1

1 7

1.

Biology

Library

2

-4

ClenCra,l Research Library

5. Reactor Di.vision

Library-

6-7.

ORTn.

- Y - L 2

Technical. Library

Document

R e ferenc S e c tLori

8-27.

Laboratory

Records

Department

28. 1,Bboratory liecords,

QRTU..I

R.C.

29. P. S .

Balier

30. E . E.

Beaueh-amp

3 1 _ .

71. A.

B u t l e r

3 2 .

J.

11. Gi l . l e t t c

33.

K.

W.

Iiaff

34. E .

E. Ke'cchen

EXTEfUAL

DZSTRIBWION

35

H.

IT. L af f e r t y

36. H.

G. MacPherson

37.

C. E. Lmib

38.

C.

E.

Larson

39. R.

G.

Niemeycr

40-43. C. L. Ot t inger

4.4. .

E.

Pie r ce

45.

J'. C. Pigg

46. A. E'.

Xupp

4 7.

H Russe:1.L

48-51. R, Id.

Schaich

52. M. J. Skinner

5 3 . A. M.

Weinberg

54-Research.

and

Developen-i;

Division,

AEC,

O R 0

55-512.

Given distribution as shown i n TID-45OO (39th ed.) .under

Isotopes -inkus trial

Teelinology category

(75

copies -

CFSTI)