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EFFECTS OF IONIZING RADIATION

ON STABILIZED PHOTO OPTICS I

I

Odober 1969 I

, I I

AEC RESEARCH &

DEVELOPMENT REPORT

1 _ I -- -- I U

~A~FE~E 'ME~~O~WALINS~TUTE NORTHWEST PACIFIC IYORTldWESt LABORATQRIES

B~TTELLE B@ULEVARD, P. 0. BUI 999. RICHLAND. )WSHINGTON 89362

367g 00061 4935 ij!\J'k\'L - 11 3 7

U C - 4 0 , R a d i a t i o n L f f e c t s

on M a t e r i a l s

E F F E C T S OF I O N I Z I N G R A D I A T I O N ON

S T A B I L I Z E D PHOTO O P T I C S

J . H . K l e i n p e t e r

M e t a l l u r g y and Ceramics Depar tment Chemis t ry and b l e t a l l u r g y D i v i s i o n

and

IA!. J . C l a r e *

I s s u e d By

FFTF E n g i n e e r i n g Depar tment

O c t o b e r 1969

"Wol l ensak , I n c o r p o r a t e d 850 Hudson Avenue R o c h e s t e r , New York 14621

BATTELLE MEMORIAL INSTITUTE PACIFIC NORTHWEST LABORATORIES RICHLAND, WASHINGTON 99352

Printed in the United States of America Available from

Clearinghouse for Federal Scientific and Technical Information National Bureau of Standards, U.S. Department of Commerce

Springfield, Virginia 22151 Price: Printed Copy $3.00; Microfiche $0.65

E F F E C T S OF I3?!IZIidG R A D I A T f a N O N

S T A B I L I Z E D P H O T O O P T I C S

J . H. K l e i n p e t e r a n d W . J . C l a r . 2

A B S T R A C T

S e v e r a l nonbrowning l e n s e s were t e s t e d f o r u s e f u l l i f e

i n a r a d i a t i o n f i e l d . I n c l u d e d i n t h e t e s t were a 30-150 mm

v a r i a b l e f o c a l - l e n g t h o r "zoom" l e n s , f i x e d f o c a l - l e n g t h l e n s e s

i n 1 / 2 - i n . f / 2 . 5 , 1 - i n . f / 2 . 5 and 4 - i n . f / 2 . 5 s i z e s , and s u i t -

a b l e c o n t r o l s of c o n v e n t i o n a l g l a s s . A l l t h e nonbrowning l e n s e s

were u s e f u l beyond 10' r a d t o t a l i n t e g r a t e d d o s e , and t h e 1 - i n .

f / 2 . 5 was u s a b l e a f t e r 2 x 1 0 ' ~ r a d . Coupons of t h e g l a s s e s

used i n t h e manufac tu re of t h e s e l e n s e s were i r r a d i a t e d and

t e s t e d f o r changes i n r e f r a c t i v e index and v i s i b l e l i g h t

t r a n s m i s s i o n .

iii

CONTENTS

INTRODUCTION . 1

EXPERIMENTAL PROCEDURE . 4

CONCLUSIONS. . 27

NOTES ON SPECTROPHOTOMETER SCANS . . 30

F I G U R E S

General Arrangement of Equipment for Measurement of Light Transmission of Test Lenses 6

Light Transmission Measuring Equipment with Lens and Photocell Uncovered 7

Light Source Showing Voltage Regulator, Autotrans- former, Meters, and Photoflood Lamp in Test Position 8

Photometer, Photocell, and Lens in Test Position 9

General View of 3730 Building Irradiation Facility 10

Percent Light Transmission of Sample S 714-297 Compared to Air Versus Wavelength of Visible Light 16

Percent Light Transmission of Sample PM 681-320 Compared to Air Versus Wavelength of Visible Light 17

Percent Light Transmission of Sample BL 649-338 Compared to Air Versus Wavelength of Visible Light 18

Percent Light Transmission of Sample PM 620-602 Compared to Air Versus Wavelength of Visible Light 19

Percent Light Transmission of Sample BL 617-366 Compared to Air Versus Wavelength of Visible Light 20

Percent Light Transmission of Sample S 612-581 Compared to Air Versus Wavelength of Visible Light 21

Percent Light Transmission of Sample PM 603-502 Compared to Air Versus Wavelength of Visible Light 22

Percent Light Transmission of Sample BL 573-574 Compared to Air Versus Wavelength of Visible Light 23

Percent Light Transmission of Sample BL 541-599 Compared to Air Versus Wavelength of Visible Light 24

Percent Light Transmission of Sample S 520-617 Compared to Air Versus Wavelength of Visible Light 2 5

Percent Light Transmission of Sample BL 517-645 Compared to Air Versus Wavelength of Visible Light 26

vii

E F F E C T S O F I O N I Z I N G R A D I A T I O N ON

S T A B I L I Z E D PHOTO O P T I C S

J . H . K l e i n p e t e r a n d W . J . C l a r e

I N T R O D U C T I O N

Many o f t h e p r o c e d u r e s and m a n i p u l a t i o n s r e q u i r e d i n t h e

n u c l e a r i n d u s t r y must b e per formed remote ly w i t h s e v e r a l f e e t

o f s h i e l d i n g between t h e o p e r a t o r and t h e t a s k b e i n g per formed.

T h i s r e q u i r e m e n t h a s r e s u l t e d i n t h e development of many h i g h l y

v e r s a t i l e m a n i p u l a t i n g t o o l s c o v e r i n g t h e gamut from s i m p l e

tongs t o mechan ica l and e l e c t r o - m e c h a n i c a l hands c a p a b l e of

v e r y d e l i c a t e mot ion and p o s s e s s i n g g r e a t s t r e n g t h .

The problems a s s o c i a t e d w i t h v iewing have r e s u l t e d i n a

wide v a r i e t y o f s o l u t i o n s r a n g i n g from m i r r o r s t o s h i e l d i n g

windows and t o v e r y complex, h i g h l y v e r s a t i l e p e r i s c o p e s .

With t h e i n c r e a s e of r a d i a t i o n l e v e l s and t h e u s e of more

mass ive s h i e l d i n g , d i r e c t v iewing th rough h i g h d e n s i t y g l a s s o r

l i q u i d s h i e l d i n g windows becomes l e s s s a t i s f a c t o r y . Use of

l e a d g l a s s s h i e l d i n g windows 4 f t i n t h i c k n e s s i s n o t uncommon.

L i g h t l o s s e s th rough windows o f such t h i c k n e s s a r e h i g h and

t h e l o s s e s th rough even t h i c k e r windows would b e a l m o s t

i n t o l e r a b l e .

U n t i l t h e development of c l o s e d - c i r c u i t t e l e v i s i o n , view-

i n g was p o s s i b l e from a few r i g i d l y f i x e d p o i n t s and i n o n l y a

narrow range o f m a g n i f i c a t i o n . T e l e v i s i o n cameras, on t h e

o t h e r hand, can b e mounted on movable p l a t f o r m s o r booms and

can a c c e p t l e n s e s w i t h a wide r ange o f f o c a l l e n g t h s . Now,

f o r t h e f i r s t t i m e , v iewing i s n o t r e s t r i c t e d t o a d i r e c t l i n e -

o f - s i g h t a r rangement o f p r i sms and m i r r o r s .

From t h e o u t s e t , r a d i a t i o n - i n d u c e d d a r k e n i n g o f t h e g l a s s

components of t h e v iewing d e v i c e s has been a s e r i o u s problem

and t e l e v i s i o n v iewing sys t ems a r e no e x c e p t i o n .

Glass exposed to a field of ionizing radiation tends to

darken with exposure. This phenomenon is caused by the forma-

tion of color absorption centers accompanying the electron scat-

tering. Electrons ejected from their normal positions are cap-

tured in lattice defects forming "f" centers which absorb in the

visible spectrum. At the same time, the site vacated by the

electron forms a "V" center which does not absorb light.

Two methods developed for solving this problem have been

by (1) increasing the conductivity of the glass, and (2) shift-

ing the color of the absorption band outside the visible spec-

trum. Increasing the electrical conductivity accelerates anneal-

ing by increasing the rate at which the electrons can escape the

"f" centers and fill in the "hole" at the "V" center. Conduc-

tivity can be increased either by increasing the concentration

of alkali metal ions or by raising the temperature of the glass.

At temperatures between 100 and 500 "C, a 30' rise causes approxi-

mately an order of magnitude increase in conductivity for many

of our common glasses. This effect, strictly a "rule-of-thumb"

type relationship which should be used with caution, is included

only to indicate the temperature necessary for reducing the anneal-

ing time to a practical level.

The wavelength of the color absorption band is, to a degree,

a characteristic of the chemical makeup of the glass. The addi-

tion of even a small amount of certain chemicals can cause a

shift in the wavelength of the "f" center absorption. One to

3% of cerium oxide will often shift the wavelength of the absorp-

tion band outside the visible spectrum, and the amount of ioniz-

, ing radiation needed to cause a disturbing amount of darkening

will be increased several orders of magnitude.

The addition of cerium oxide to a glass melt, however, adds

an overall yellowish cast to the glass and reduces its light

transmission capability. This radiation stabilizer thus must

be added with caution and its benefits carefully balanced against

its faults.

I n a d d i t i o n t o g l a s s damage, t h e e f f e c t of i o n i z i n g r a d i a -

t i o n on e l e c t r o n i c components of t h e l ens -camera sys tem must

a l s o be c o n s i d e r e d . Much p r o g r e s s has been made i n t h e r a d i a -

t i o n h a r d e n i n g of t h e s e s y s t e m s , and improvements i n t h i s f i e l d

a r e expec ted t o c o n t i n u e .

With t h e adven t of t h e v a r i a b l e f o c a l - l e n g t h l e n s , t h e

problem o f remote l e n s change has been s i m p l i f i e d . S e v e r a l

m a n u f a c t u r e r s , b o t h i n t h i s c o u n t r y and ab road , have o f f e r e d

v a r i a b l e f o c a l - l e n g t h o r "zoom" l e n s e s a d a p t e d f o r remote o p e r a -

t i o n of t h e diaphragm, f o c u s , and zoom f u n c t i o n s . U n t i l r e c e n t l y ,

none of t h e s e l e n s e s were made o f nonbrowning g l a s s . However,

Wollensak, I n c . now o f f e r s s e v e r a l nonbrowning l e n s e s s u i t a b l e f o r u s e on t e l e v i s i o n cameras. These a r e p o t e n t i a l l y u s e f u l

i n s e v e r a l phases of t h e o p e r a t i o n and main tenance of t h e F a s t

F lux T e s t F a c i l i t y . T h i s r e p o r t d e s c r i b e s t h e s t u d y and e v a l u -

a t i o n of s e v e r a l o f t h e nonbrowning l e n s e s produced by Wol lensak .

Because of i t s s u p e r i o r m a n i p u l a t i v e p o t e n t i a l i n a r emote ly

c o n t r o l l e d and s u s t a i n e d o p e r a t i o n , t h e v a r i a b l e f o c a l - l e n g t h

o r "zoom" l e n s h a s been s t u d i e d i n g r e a t e s t d e t a i l and t h e

r e s u l t s emphasized i n t h i s r e p o r t . T h i s s t u d y was a c o o p e r a t i v e

e f f o r t i n which Wollensak f u r n i s h e d t h e l e n s e s , B a t t e l l e - N o r t h -

w e s t per formed t h e i r r a d i a t i o n s , and b o t h p a r t i c i p a t e d i n i n t e r -

p r e t i n g and r e p o r t i n g t h e r e s u l t s .

A s t h e s t u d y p r o g r e s s e d , i t became a p p a r e n t t h a t much u s e -

f u l i n f o r m a t i o n c o u l d be g a i n e d by i r r a d i a t i n g each s e p a r a t e

t y p e of g l a s s i n t h e s e l e n s e s a s an i n d i v i d u a l e n t i t y r a t h e r

t h a n a s p a r t of a comple ted l e n s sys tem. I n c l u d e d i n t h i s

s t u d y , t h e r e f o r e , was t h e examina t ion of 11 s e p a r a t e t y p e s of

g l a s s used i n t h e d e s i g n of t h e s e l e n s sys t ems .

T h i s work was u n d e r t a k e n under te rms of S p e c i a l Agreement

BSA 510 and Prime C o n t r a c t AT (45-1) - 1 8 3 0 . The j u s t i f i c a t i o n

of t h e work and working ar rangement i s d e t a i l e d i n t h a t c o n t r a c t .

E X P E R I M E N T A L PROCEDURE

The l e n s o f p r imary i n t e r e s t f o r t h i s t e s t was t h e f / 2 . 7 ,

30-150 mm nonbrowning r e m o t e - c o n t r o l zoom l e n s . A l e n s of

s i m i l a r s p e c i f i c a t i o n b u t of c o n v e n t i o n a l g l a s s was used a s a

c o n t r o l . Lenses o f 4 , 1, and 1 / 2 - i n . f o c a l l e n g t h s were a l s o

i n c l u d e d a s a t e s t o f o t h e r nonbrowning g l a s s sys tems . I n each

c a s e , a c o n v e n t i o n a l g l a s s c o n t r o l was i n c l u d e d .

Two i r r a d i a t i o n f a c i l i t i e s were used i n t h e s e t e s t s . Both

were of t h e swimming poo l t y p e w i t h a c o b a l t 60 s o u r c e . The

more c o n v e n i e n t i n s t a l l a t i o n was t h e one i n 3730 B u i l d i n g of t h e

P a c i f i c Northwest L a b o r a t o r i e s . I tems t o be i r r a d i a t e d i n t h i s

f a c i l i t y were i n t r o d u c e d i n t o a p o s i t i o n i n s i d e t h e a r r a y of

c o b a l t 60 r o d s by means of a permanent ly p o s i t i o n e d 2 - i n . OD

t u b e . A t t h e t ime of t h i s t e s t , t h e dose r a t e a t t h i s p o s i t i o n

was 2 x l o 7 r a d / h r . A 4 - i n . s t a n d a r d we igh t s t e e l p i p e was a l s o

a v a i l a b l e f o r i t e m s t o o l a r g e f o r t h e 2 - i n . t u b e s . T h i s p i p e , 6 l o c a t e d o u t s i d e t h e a r r a y , was r a t e d a t 2 . 2 x 10 r a d / h r a t t h e

t ime of t h i s t e s t .

The f a c i l i t y o p e r a t e d by Douglas Uni ted Nuclear a t t h e i r

l O O K r e a c t o r s i t e was used f o r i t e m s t o o l a r g e f o r t h e 4 - i n .

p i p e . T h i s f a c i l i t y i s equipped w i t h a 6 - i n . p i p e i n t h e c e n t e r

o f t h e c o b a l t f u e l a r r a y . The dose r a t e a t t h e t ime of t h i s t e s t

was 2 . 2 x l o 6 r a d / h r .

The exposure l e v e l s i n t h e s e f a c i l i t i e s were measured w i t h

chemical d o s i m e t e r s a t t h e t ime of i n s t a l l a t i o n . Subsequent

m o n i t o r i n g was per formed by means o f i o n i z a t i o n chambers o r by

c a l c u l a t i o n from t h e known decay r a t e of c o b a l t 60. I n t h e

s t r i c t e s t s e n s e , d o s e r a t e s e x p r e s s e d h e r e a r e i n te rms o f energy

absorbed by t h e chemica l d o s i m e t e r , b u t s i n c e most o t h e r f i e l d

s t r e n g t h measurements w i l l be on a s i m i l a r b a s i s , i t would s e r v e

no u s e f u l purpose t o c o n v e r t t h e s e measurements t o a c t u a l energy

absorbed by t h e g l a s s o r by o t h e r m a t e r i a l of t h e s p e c i f i c l e n s

system.

During t h e c o u r s e of t h e exposure , r a d i a t i o n h e a t i n g

caused a t e m p e r a t u r e r i s e i n t h e l e n s e s . For r e l a t i v e l y long

te rm exposures , t h e t e m p e r a t u r e s t a b i l i z e d a t approx ima te ly

80 O C . Measurements o f o p t i c a l c h a r a c t e r i s t i c s were made of

t h e l e n s a s soon a s p r a c t i c a l a f t e r removal from t h e s o u r c e .

A l l l e n s e s were i n s p e c t e d and l i g h t t r a n s m i t t i n g c h a r a c -

t e r i s t i c s measured b e f o r e t h e s t a r t o f t h e t e s t . A f t e r each

increment o f e x p c s u r e , each l e n s was a g a i n i n s p e c t e d f o r p h y s i -

c a l o p e r a t i o n and t h e l i g h t t r a n s m i s s i o n measured. Per formance 6 of t h e s e i n s p e c t i o n s and measurements was p lanned a f t e r 10 ,

7 8 9 10 , 10 , 10 , and 10" r a d s t o t a l i n t e g r a t e d dose . A t e l e -

v i s i o n camera and moni to r were a l s o s e t up w i t h a r e s o l u t i o n

c h a r t t o mon i to r r e s o l u t i o n .

L i g h t t r a n s m i s s i o n was measured w i t h a Gamma Model 700-W

photometer equipped w i t h a c o s i n e r e c e p t o r . The l i g h t s o u r c e

was a 500-W r e f l e c t o r - p h o t o f l o o d . To minimize f l u c t u a t i o n s i n

l i g h t i n t e n s i t y , a Sorensen Model AP 1010 v o l t a g e r e g u l a t o r

was used i n t h e power l i n e w i t h an a u t o t r a n s f o r m e r t o r e g u l a t e

t h e a c t u a l v o l t a g e t o t h e lamp. A v e r y s e n s i t i v e v o l t m e t e r

and ammeter were used t o mon i to r power t o t h e lamp. The g e n e r a l

s e t - u p i s shown i n F i g u r e s 1 th rough 5.

The l e n s u n d e r t e s t was mounted on t h e p h o t o c e l l o f t h e

photometer and s e t up on a s t a n d approx ima te ly 8 f t from t h e

l i g h t s o u r c e . The p o s i t i o n s o f t h e p h o t o c e l l and l i g h t s o u r c e

were n o t changed d u r i n g t h e t e s t . A l l e x t e r n a l l i g h t was

s h i e l d e d from t h e t e s t a s shown i n F i g u r e 1.

Befo re i r r a d i a t i o n , each l e n s was mounted on t h e p h o t o c e l l

and t h e m e t e r a d j u s t e d t o r e a d t h e l i g h t t r a n s m i t t e d a s 1 0 0 % .

The l e n s was t h e n removed and t h e r e a d i n g r e c o r d e d a s t h e pho to -

me te r r e a d i n g f o r t h a t l e n s . T h i s v a l u e v a r i e d s l i g h t l y from

l e n s t o l e n s .

Neg 0681451

FIGURE 5 . G e n e r a l View o f 3730 B u i l d i n g I r r a d i a t i o n F a c i l i t y

A f t e r exposure t o t h e c o l b a l t 60 s o u r c e , each l e n s was

remounted on t h e p h o t o c e l l and i t s l i g h t t r a n s m i s s i o n measured

w i t h a l l t h e mechanica l a d j u s t m e n t s t h e same a s f o r t h e s t a n d -

a r d u n i r r a d i a t e d measurement.

To obse rve t h e e f f e c t of i r r a d i a t i o n on t h e r e s o l u t i o n o f

t h e l e n s e s under t e s t , a Motorola Model S1120C camera and a

Genera l E l e c t r i c Model 25B2 moni tor were connec ted i n c l o s e d

c i r c u i t . R e s o l u t i o n was r e a d d i r e c t l y from a RETMA 1956 r e s o -

l u t i o n c h a r t l i g h t e d a t 2 8 - 3 0 f t - c a n d l e s .

T h i s r e s o l u t i o n t e s t was s e t up, n o t a s an e v a l u a t i o n o f

t h e r e s o l v i n g c a p a b i l i t y o f t h e l e n s b u t a s a means o f d e t e c t -

i n g g r o s s changes i n r e s o l u t i o n . Because equipment f o r accu-

r a t e l y e v a l u a t i n g l e n s r e s o l u t i o n was n o t a v a i l a b l e , t h i s method

of moni to r ing was chosen r a t h e r t h a n t o i g n o r e comple te ly t h i s

a s p e c t o f l e n s per formance . I t s h o u l d b e p o i n t e d o u t t h a t ,

inasmuch a s t h e camera was n o t i n good a d j u s t m e n t , t h e s e d a t a

a r e q u a l i t a t i v e o n l y . The c h a r t was i l l u m i n a t e d by ambient

l i g h t from f l u o r e s c e n t f i x t u r e s abou t 15 f t above t h e f l o o r .

The l i g h t i n t e n s i t y a t t h e p o s i t i o n o f t h e c h a r t was measured

t o be 28-30 f t - c a n d l e s . A Weston mete r equipped w i t h a c o s i n e

f i l t e r was used f o r t h i s measurement.

The r e s o l v i n g c h a r a c t e r i s t i c s o f a l l l e n s e s t e s t e d were

w e l l known f o r t h e u n i r r a d i a t e d s t a t e . I n t h e i n t e r e s t o f t i m e

s a v i n g , t h e r e f o r e , no l o c a l measurements were made b e f o r e t h e

s t a r t of t h e i r r a d i a t i o n . The f i r s t i nc rement of exposure of

t h e 1 - i n . f / 2 . 5 l e n s r e q u i r e d o n l y t h r e e min. A t t h e end o f

t h i s f i r s t exposure s t e p , and because t h e camera f o r t h e r e s o -

l u t i o n t e s t had n o t y e t been l o c a t e d , no r e s o l u t i o n r e a d i n g was 6 made on t h a t l e n s a f t e r 10 r a d .

The r e s o l u t i o n i n l i n e s p e r i n c h r e p o r t e d h e r e does n o t

approach t h e r e s o l u t i o n de te rmined on an o p t i c a l bench f o r t h e s e

same l e n s e s . The r e s o l u t i o n does , however, r e f l e c t t h e l i m i t

BNWL- 1137

imposed by t h e camera-moni tor sys t em. The r e s o l v i n g power of

t h e l e n s must be r educed below t h a t of t h e camera-moni tor combi-

n a t i o n t o p e r m i t d e t e c t i o n o f any change. For a r e s o l u t i o n

t e s t , t h e l e n s must b e mounted on t h e camera, f o c u s e d a s a c c u r a t e l y

a s p o s s i b l e on t h e c h a r t , t h e i r i s diaphragm a d j u s t e d t o t h e p r e -

s e l e c t e d f i g u r e , and t h e r e s o l u t i o n r e a d on t h e m o n i t o r . When

t h e l e n s c a n n o t be f o c u s e d o r t h e diaphragm a d j u s t e d , t h e r e s o l v -

i n g c h a r a c t e r i s t i c o f t h e sys t em canno t b e . d e t e r m i n e d . T h i s

s i t u a t i o n o c c u r r e d a f t e r exposure of t h e 1 - i n . f / 2 . 5 l e n s t o 10 9

8 r a d and a f t e r exposure of t h e zoom l e n s t o 10 r a d . The o t h e r

two l e n s e s under e v a l u a t i o n o p e r a t e d e a s i l y a f t e r exposure t o 8 10 r a d . R e s o l u t i o n t e s t r e s u l t s a r e r e p o r t e d on T a b l e 1.

A l l l e n s e s were i n s p e c t e d and l i g h t t r a n s m i s s i o n d e t e r m i n e d 6 b e f o r e t h e s t a r t o f t h e t e s t . A f t e r 1 x 10 r a d t o t a l e x p o s u r e ,

each l e n s was i n s p e c t e d and l i g h t t r a n s m i s s i o n d e t e r m i n e d . These

d a t a a r e r e p o r t e d i n T a b l e 2 . The c o n v e n t i o n a l g l a s s l e n s e s

had da rkened s o s e v e r e l y a t t h i s p o i n t t h a t t h e y were t o t a l l y

u s e l e s s f o r f u r t h e r t e s t p u r p o s e s .

The l e n s e s were t h e n r e t u r n e d t o t h e s o u r c e and t h e i r r a d i a -

t i o n c o n t i n u e d . A l l f o u r of t h e s t a b i l i z e d l e n s e s s u r v i v e d t h e 7 8 10 r a d exposure and t h e t e s t was t h e r e f o r e c o n t i n u e d t o 10 .

The mechan ica l f u n c t i o n o f t h e zoom l e n s was i n o p e r a t i v e a t t h i s

p o i n t , w i t h o n l y t h e l i g h t t r a n s m i s s i o n b e i n g measured. A f t e r 9 10 r a d , t h e mechan ica l o p e r a b i l i t y o f t h e f i x e d f o c a l l e n g t h

l e n s e s was s o s e r i o u s l y impa i red t h a t normal a d j u s t m e n t s were

n o t p o s s i b l e . D e s p i t e t h i s , t h e 1 - i n . f / 2 . 5 l e n s was i r r a d i a t e d

t o l o l o r a d . A t t h i s p o i n t , a l l t e s t l e n s e s were r e t u r n e d t o

Wollensak f o r mechan ica l r e p a i r .

I n s p e c t i o n r e v e a l e d s e r i o u s damage t o t h e o r g a n i c p a r t s .

The l u b r i c a n t was ha rdened and v e r y v i s c o u s , p l a s t i c g e a r s had

been s t r i p p e d a s a r e s u l t o f t h e i n c r e a s e d l o a d , and t h e p l a s t i c

c l u t c h p l a t e s had d e t e r i o r a t e d b a d l y .

T A B L E 2 . R e s o l u t i o n i n L i n e s Per I n c h

T o t a l I n t e g r a t e d D o s e , r a d

T e s t 1 o 6 1 0 1 o 8 L e n s f / N o . C e n t e r E d g e C e n t e r E d g e C e n t e r E d g e

Zoom F u l l o p e n 4 5 0 3 0 0 4 0 0 3 0 0 ( 1 )

1 / 2 - i n . f / 2 . 5 5 . 6 5 5 0 3 0 0 4 6 0 0 3 0 0 4 5 0 3 0 0

( l ) A t l o 8 rad e x p o s u r e , t h e zoom l e n s was m e c h a n i c a l l y i n o p e r a t i v e . For t h i s r e a s o n , no r e s o l u t i o n o b s e r v a t i o n s couZd be made.

( ' ) ~ t 10' rad e z p o s u r e , t h e I - i n . Lens was mechan ica lZy i n o p e r a t i v e . For t h i s r e a s o n , no f u r t h e r r e s o l u t i o n o b s e r v a t i o ~ s couZd be made.

TABLE 2 . L i g h t T r a n s m i s s i o n o f I r r a d i a t e d Lenses i n Percen t

Ex o s u r e , r a d

0 l o 6 10- As Maximum ( 4 ) A f t e r L e n s I r r a d i a t e d C l e d n i n q

N . B . Zoom 1 0 0 5 8 4 3 2 7 ( 1 ) g - 3 0 ( ~ ) ( 1 . 2 l o 9 ) 9 ( 2 x l o g r a d ) ( 2 x 1 0 r a d )

N . B . 1 1 2 - i n . f J 2 . 5 1 0 0 5 5 6 5 5 2 1 6 3 1 2 9 ( 2 x 1 0 l 0 r a d ) ( 2 x l 0 l 0 r a d )

N . B . 1 - i n . f / 2 . 5 1 0 0 9 8 9 8 9 7 8 9 8 4 ( 3 ) 7 3 8 1 ( 2 x l o g r a d ) ( 2 x l o g r a d )

N . B . 4 - i n . f / 2 . 5 1 0 0 6 9 7 7 6 9 5 8 6 2 6 5

S t d . Zoom 1 0 0 0

S t d . 1 - i n . f / 1 . 5 1 0 0 0 . 4

S t d . 4 - i n . f / 2 . 5 1 0 0 0 . 4

( ' ) A f t e r l o 8 r a d , t h e m e c h a n i c a l movements were f r o z e n and an o i l - L i k e c o a t i n g was n o t e d on t h e g l a s s .

( ' ) !There was a v o i l - l i k e f i l m on t h e gZass a f t e r t h i s e x p o s u r e . L i g h t t r a n s m i s s i o n w i t h t h e f i l m was 9 % and 3 0 % a f t e r c 2 e a n i n g . The " o i l " may have come from diaphragm l u b r i c a n t .

( 3 ) ~ f t e r 10' r a d , t h e m e c h a n i c a l a d j u s t m e n t s wouZd n o t o p e r a t e . However, i r r a d i a t i o n was c o n t i n u e d t o r a d .

( 4 ) ~ h e n i n s p e c t e d a t t h e WoZlensak f a c t o r y a f t e r t h i s i r r a d i a t i o n , a f i l m was s e e n on t h e g l a s s . L i g h t t r a n s m i s s i o n measurements u e r e made b e f o r e and a f t e r remova l o f t h e d e p o s i t .

The zoom l e n s was r eassembled a f t e r a l l o p t i c a l p a r t s had

been c l e a n e d . The p l a s t i c g e a r s were r e p l a c e d w i t h m e t a l , t h e

c l u t c h p l a t e s w i t h c a r b o n , and a d r y f i l m l u b r i c a n t used on a l l

c o n t a c t s u r f a c e s . The f i x e d f o c a l l e n g t h l e n s e s were c l e a n e d ,

d e g r e a s e d , and l u b r i c a t e d w i t h a d r y f i l m l u b r i c a n t .

A l l f o u r l e n s e s were t h e n r e t u r n e d t o B a t t e l l e - N o r t h w e s t

f o r f u r t h e r i r r a d i a t i o n . The 1 / 2 - i n . and t h e 4 - i n . l e n s e s were 9

each g i v e n an a d d i t i o n a l 10 r a d , w h i l e t h e 1 - i n . l e n s was g i v e n

an a d d i t i o n a l lo1' r a d . The zoom l e n s was exposed t o 1.1 x 10 9

r a d . The mechan ica l f u n c t i o n s of t h i s l e n s were o p e r a t e d a t t h e

end o f e a c h inc remen t w h i l e s t i l l i n t h e r a d i a t i o n f i e l d , t h e n

removed, i n s p e c t e d , and r e t u r n e d t o t h e i r r a d i a t i o n f a c i l i t y .

U n f o r t u n a t e l y , t h e l a c k o f a camera a t t h i s t ime compel led t e r m i -

n a t i o n o f t h e r e s o l u t i o n t e s t .

Mechanica l o p e r a t i o n s of t h e zoom l e n s c e a s e d t o f u n c t i o n 9 a f t e r 1.1 x 10 r a d e x p o s u r e , a g a i n from l u b r i c a t i o n and p l a s t i c

p a r t f a i l u r e .

I n t h e meantime, Wollensak had p r e p a r e d f i v e coupons e a c h

o f 10 d i f f e r e n t nonbrowning g l a s s b l a n k m a t e r i a l s and f o u r cou-

pons of an e l e v e n t h t y p e of g l a s s . These coupons were c u t t o

0.500 i n . by 0.500 i n . by 2.0 i n . and p o l i s h e d on two o p p o s i t e

long f a c e s .

Samples were i d e n t i f i e d by m a n u f a c t u r e r ' s name, t h e i n d e x

o f r e f r a c t i o n , and t h e d i s p e r s i o n , o r "V" v a l u e . The code used

t h e m a n u f a c t u r e r ' s i n i t i a l and two t h r e e - d i g i t numbers s e p a r a t e d

by a hyphen. The f i r s t g roup of numbers c o n s t i t u t e d t h e l a s t

t h r e e d i g i t s of r e f r a c t i v e i n d e x f o r t h e Sodium "DM l i n e , and

t h e second group d e n o t e d t h e d i s p e r s i o n v a l u e w i t h o u t t h e d e c i -

mal p o i n t . The samples were :

BL - Bausch 6 Lomb., R o c h e s t e r , New York S - O p t i c a l g l a s s d i s t r i b u t e d by F i s h -

Shurman Corp . , New R o c h e l l e , N . Y . PM - S o v i r e l Department , P a r r a - M a n t o i s ,

P a r i s , France .

One of t h e f i v e coupons of each sample was k e p t a s a con- 7 8 t r o l , and one of e a c h o f t h e o t h e r f o u r exposed t o 10 , 10 ,

l o 9 , and l o l o r a d . I n t h e c a s e of t h e BL 573-574, t h e 10 7

exposure was o m i t t e d because of t h e l a c k of a f i f t h coupon.

A f t e r i r r a d i a t i o n , each coupon was measured f o r l i g h t

t r a n s m i s s i o n t h r o u g h o u t t h e v i s i b l e r ange on a Beckman DB 200

double beam s p e c t r o p h o t o m e t e r . T h i s measurement was compared

t o a s i m i l a r s c a n of t h e u n i r r a d i a t e d c o n t r o l . No a t t e m p t

was made t o minimize o r s t a n d a r d i z e t h e t ime l a p s e between

removal from t h e r a d i a t i o n f i e l d and t h e l i g h t t r a n s m i s s i o n

measurement. I n no c a s e was t h e d e l a y l o n g e r t h a n 7 2 h r s .

These r e s u l t s were r ep roduced a s r e c o r d e d , w i t h a t r a c e

f o r each exposure l e v e l on t h e same g raph . A s can be r e a d i l y 1

s e e n i n F i g u r e s 6 th rough 16 , t h e l o s s i s much l e s s a t t h e r e d

end o f t h e spec t rum t h a n a t t h e b l u e end. T h i s r e s u l t might

s u g g e s t t h e i n c a n d e s c e n t o r sodium vapor l i g h t s t o be much more

d e s i r a b l e f o r u s e w i t h t e l e v i s i o n v iewing sys tems t h a n t h e mer- [ I cury vapor l i g h t s , s o o f t e n used i n h i g h l e v e l r a d i a t i o n c e l l s . 1 I

I n t h e c a s e of t h e a c t u a l s p e c t r o p h o t o m e t e r s c a n s , t h e I

i

l i g h t t r a n s m i s s i o n of each sample a t each r a d i a t i o n l e v e l i s

compared t o t h a t of a i r t h roughou t t h e v i s i b l e spec t rum

( F i g u r e s 6 through 1 6 ) ,

See Note 1

Transmission, %

FIGURE 6 . P e r c e n t L i g h t T r a n s m i s s i o n o f Sample S 7 1 4 - 2 9 7 Compared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Transmission, %

F I G U R E 7 . P e r c e n t L i g h t T r a n s m i s s i o n o f Sample PM 6 8 1 - 3 2 0 Compared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

See Note 3

Transmission, %

F I G U R E 8 . P e r c e n t L i g h t T r a n s m i s s i o n o f SampZe B L 6 4 9 - 3 3 8 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b Z e L i g h t

F I G U R E 9 .

Transmission, %

P e r c e n t L i g h t T r a n s m i s s i o n o f Sample PM 620-602 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

See Note 4

0 20 40 60 80 100 120

Transmission, %

FIGURE 10 . P e r c e n t L i g h t T r a n s m i s s i o n o f Sample B L 617-366 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Transmission, %

FIGURE 11. P e r c e n t L i g h t T r a n s m i s s i o n o f Sample S 6 1 2 - 5 8 1 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Transmission, %

FIGURE 1 2 . P e r c e n t L i g h t T r a n s m i s s i o n of Sample PM 6 0 3 - 5 0 2 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Transmission, %

FIGURE 23. P e r c e n t L i g h t T r a n s m i s s i o n o f Sample B L 573-574 Compared t o A i r V e r s u s WaveZength o f V i s i b l e L i g h t

Transmission, %

F I G U R E 1 4 . P e r c e n t L i g h t T r a n s m i s s i o n o f Sample B L 5 4 1 - 5 9 9 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

See Note 5

0 20 40 60 80 100 120

Transmission, 70

FIGURE 1 5 . P e r c e n t L i g h t T r a n s m i s s i o n o f Sample S 520-617 Com- pared t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Transmission, %

FIGURE 1 6 . P e r c e n t L i g h t T r a n s m i s s i o n o f S a m p l e B L 517-645 Com- p a r e d t o A i r V e r s u s W a v e l e n g t h o f V i s i b l e L i g h t

Upon r e t u r n t o Wollensak, t h e r e f r a c t i v e i n d e x of each

sample was a g a i n de te rmined . These d a t a a r e p r e s e n t e d i n

Tab le 3.

C O N C L U S I O N S

I t a p p e a r s t h a t , o p t i c a l l y , t h e nonbrowning zoom l e n s e s 9 can p r o v i d e a c c e p t a b l e s e r v i c e w e l l beyond 10 r a d t o t a l expo-

s u r e . A t t h i s p o i n t , a l o s s of two t o t h r e e s t o p s can be

e x p e c t e d . T h i s l o s s no rmal ly can be t o l e r a t e d , s i n c e t h a t

amount of leeway i s d e s i g n e d i n t o t h e t o t a l sys tem.

The mechanica l o p e r a t i o n of t h e l e n s was a d e q u a t e b u t 9 s l u g g i s h a f t e r 1 x 1 0 r a d t o t a l exposure . C a r e f u l c h o i c e o f

components and l u b r i c a n t s s h o u l d e x t e n d t h e mechanica l l i f e

t o w e l l beyond t h i s exposure .

Of t h e f i x e d f o c a l l e n g t h nonbrowning l e n s e s t e s t e d , t h e

1 - i n . f / 2 . 5 was t h e b e s t . L i g h t t r a n s m i s s i o n a f t e r 2 x 10 10

r a d exposure was reduced much l e s s t h a n one s t o p . The f o c u s

and i r i s movement were b o t h v e r y s t i f f a f t e r 1 x 10" r a d

because of i n t e r n a l c o r r o s i o n of t h e b r a s s p a r t s . The c a u s e

f o r t h i s c o r r o s i o n has n o t been i s o l a t e d .

The 4 - i n . f / 2 . 5 l e n s l o s t l e s s t h a n one s t o p a f t e r expo-

s u r e t o 2 x 10' r a d . There was no impairment o f i t s mechani- 9 c a l f u n c t i o n a f t e r 1 x 10 r a d .

The g r e a t e s t r e d u c t i o n i n l i g h t t r a n s m i s s i o n , s u s t a i n e d

by t h e 1 / 2 - i n . f / 2 . 5 l e n s , o c c u r r e d two t o t h r e e s t o p s a f t e r

2 x 10' r a d . There was no impairment of i t s mechan ica l f u n c -

t i o n a f t e r 1 x 10' r a d .

The i r r a d i a t i o n and measurement o f l i g h t t r a n s m i s s i o n and

r e f r a c t i v e index o f t h e v a r i o u s g l a s s samples has i n d i c a t e d

t h a t t h e r a d i a t i o n s t a b i l i t y of t h e nonbrowning g l a s s o f f e r e d

l e n s m a n u f a c t u r e r s i s q u i t e good. These measurements a l s o d i s -

c l o s e d t h a t l o s s i n l i g h t t r a n s m i s s i o n does n o t f o l l o w a

TABLE 3. Effect of Gamma Radiation on the Refractive Index of Glass

G l a s s S a m p l e I d e n t i f i c a t i o n T o t a l

S 7 1 4 - 2 9 7 PM 6 8 1 - 3 2 0 BL 6 4 9 - 3 3 8 PM 6 2 0 - 6 0 2 BL 6 1 7 - 3 6 6 S 6 1 2 - 5 8 1 Dose, r a d

Refractive Index, h o

A G l a s s S a m p l e I d e - n t i f i c a t i o n - T o t a l

D o s e , r a d PM 6 0 3 - 5 0 2 BL-573-574 B L 5 4 1 - 5 9 9 S 5 2 0 - 6 1 7 B L 5 1 7 - 6 4 5

Refractive Index, h o

s t r a i g h t l i n e r e l a t i o n s h i p w i t h r a d i a t i o n d o s e . I n f a c t , some

samples were found t o r e c o v e r t o a r emarkab le d e g r e e . The o b s e r v e d

changes i n r e f r a c t i v e i n d e x were , w i t h one e x c e p t i o n , l e s s t h a n

0.001. T h i s r e s u l t would i n d i c a t e no d e t e c t a b l e l o s s i n r e s o l u -

t i o n by l e n s e s made from t h e s e g l a s s e s f o r t e l e v i s i o n sys t ems

( s e e T a b l e 3 ) .

A f i l m y d e p o s i t was n o t e d on s e v e r a l of t h e comple ted

nonbrowning l e n s e s , e s p e c i a l l y t h e zoom and t h e 1 - i n . f / 2 . 5 .

T h i s f i l m was s e e n on t h e zoom l e n s a f t e r a t o t a l d o s e o f 1 . 2 9

x 10 r a d , and on t h e 1 - i n . l e n s a f t e r 2 x l o l o r a d . I t s h o u l d

b e n o t e d h e r e t h a t t h e zoom l e n s was c l e a n e d a f t e r t h e f i r s t 8 1 x 10 inc remen t a.nd t h e 1 - i n . lenr; was c l e a n e d a f t e r t h e f i r s t

1 x l o l o i n c r e m e n t . The s o ~ i ~ c e c f t h i s f i l m was p o s s i b l y t h e o i l

o r g r e a s e used t o l u b r i c a t e t h e mechan ica l components of t h e com-

p l e t e d l e n s e s . On t h e o t h e r hand, a f i l m was d e p o s i t e d on f i v e

of t h e 1 2 g l a s s coupons i r r a d i a t e d t o l o l o r a d . I n t h e c a s e o f

t h e s e coupons, each was wrapped i n d i v i d u a l l y i n new aluminum

f o i l , and s o f a r a s i s known, t h e r e was no c o n t a c t w i t h any

o r g a n i c m a t e r i a l d u r i n g i r r a d i a t i o n . T h i s would s u g g e s t

t h a t we may e x p e c t some such d e p o s i t a t e x t r e m e l y h i g h d o s e s

r e g a r d l e s s of t h e n a t u r e o f t h e l u b r i c a t i o n .

These t e s t s d e m o n s t r a t e t h a t , i n some c a s e s , t h e nonbrown-

i n g l e n s e s a r e s u p e r i o r t o t h e i r c o n v e n t i o n a l c o u n t e r p a r t by

a s much a s 10,000 t o 1. The nonbrowning zoom l e n s a p p e a r s t o

b e s u p e r i o r t o i t s c o n v e n t i o n a l g l a s s c o u n t e r p a r t by a b o u t

2,000 t o 1.

N O T E S ON S P E C T R O P H O T O M E T E R S C A N S

Note 1.

A f t e r exposure t o l o l o r a d , Sample S714-297 was c o a t e d

w i t h an opaque d e p o s i t which rubbed o f f w i t h some d i f f i c u l t y .

For t h e i r r a d i a t i o n , t h e samples were wrapped i n aluminum f o i l

t o p r e v e n t c o n t a c t between samples . A l l samples f o r each expo-

s u r e were packed t o g e t h e r i n one f o i l - c o a t e d package .

Four o t h e r s o f t h e l o l o r a d coupons a l s o were found t o b e

c o a t e d a f t e r i r r a d i a t i o n . None was a s dense o r a s d i f f i c u l t t o

remove a s was t h e c o a t i n g on Sample S714-297.

Note 2 .

Sample PM681-320. L i g h t f i l m d e p o s i t on s u r f a c e on 10 10

coupon.

Note 3 .

Sample BL648-338. L i g h t f i l m d e p o s i t on s u r f a c e of 10 10

r a d coupon.

Note 4.

Sample BL617-366. Very s m a l l amount o f f i l m d e p o s i t on

s u r f a c e o f lo1' r a d coupon.

Note 5.

Sample S520-617. Very l i g h t f i l m d e p o s i t on s u r f a c e o f

l o l o r a d coupon.

D I S T R I B U T I O N

No. of Copies

O F F S I T E

1 AEC Chicago Patent G r o u ~

G. H. Lee

31 AEC Division of Reactor Development and Technology

M. Shaw, Director, RDT Asst Dir for Nuclear Safety Analysis 6 Evaluation Br, RDT:NS Environmental C, Sanitary Engrg Br, RDT:NS Research G Development Br, RDT:NS Asst Dir for Plant Engrg, RDT Facilities Br, RDT:PE Components Br, RDT : PE Instrumentation 6 Control Br, RDT:PE Liquid Metal Systems Br, RDT:PE Asst Dir for Program Analysis, RDT Asst Dir for Project Mgmt, RDT Liquid Metals Projects Br, RDT:PM FFTF Project Manager, RDT:PM (3) Asst Dir for Reactor Engrg, RDT Control Mechanisms Br, RDT:RE Core Design Br, RDT:RE (2) Fuel Engineering Br, RDT:RE Fuel Handling Br, RDT: RE Reactor Vessels BY, RDT:RE Asst Dir for Reactor Tech, RDT Coolant Chemistry Br, RDT:RT Fuel Recycle Br, RDT:RT Fuels 6 Materials Br, RDT:RT Reactor Physics Br, RDT:RE Special Technology Br, RDT: RT Asst Dir for Engrg Standards, RDT EBR-I1 Project Manager, RDT:PM

1 AEC Idaho Operations Office

Nuclear Technology Division

C. W. Bills, Director

1 AEC San Francisco Operations Office

Director, Reactor Division

No. of Copies

4 AEC Site Renresentatives

Argonne National Laboratory Atomics International Atomic Power Development Assoc. General Electric Co.

AEC Division of Technical Information Extension

Areonne National Laboratorv

R. A. Jaross LMFBR Program Office N. J. Swanson

Atomic Power Develonment Assoc.

Document Librarian

Atomics International

FFTF Program Office (5)

Liquid Metal Information Center

J. J. Droher (2)

Babcock & Wilcox Co.

Atomic Energy Division

S. H. Esleeck G. B. Garton

BNW Representative

N. A. Hill (ZPR 111)

Combustion Engineering

1000 MWe Follow-On Study

W. P. Staker, Project Manager

BNWL- 1137

No. of Copies

5 General Electric Com~anv

Advanced Products Operation

Karl Cohen (4)

Nuclear Systems Programs

D. H. Ahmann

Gulf General Atomic Inc.

General Atomic Div

D. Coburn

Idaho Nuclear Cor~oration

D. R. deBoisblanc

Oak Ridge National Laboratory

W. 0. Harms

Stanford University

Nuclear Division Division of Mechanical Engrg

R. Sher

United Nuclear Cor~oration

Research and Engineering Center

Woller:sab, Inc.

850 Hudson Avenue Rochester, New York

W. J. Clare

Bechtel Corporation*

J. J. Teachnor, Project Administrator, FFTF

Dis tr- 3

No. of Couies

15 Westinghouse Electric Corporation*

Atomic Power Division Advanced Reactor Systems

J. C. R. Kelly

O N S I T E - H A N F O R D

1 Bechtel Cor~oration*

M. 0. Rothwell (Richland)

1 Westinehouse Electric Cor~oration*

R. Strzelecki (Richland)

4 AEC RDT Site Representative

P. G. Holsted (3) T. A. Nemzek

AEC Richland O~erations Office

J. M. Shivley

AEC Chicago Patent Group

R. K. Sharp (Richland)

Atlantic Richfield Hanford Company

W. H. Koontz

Battelle Memorial Institute

* D i s t r i b u t i o n by F F T F

No. of Copies

6 9 B a t t e l l e - N o r t h w e s t

A s t l e y B e r r e t h B l a s e w i t z Cochran Condot ta Cox de Ha las Erben Evans Gronemeyer Hammond Hofmann K l e i n p e t e r (20) L i t t l e McDonald McMahon N i g h t i n g a l e P l a t t

W . E . Roake F. P. Rober t s R . J . S q u i r e s G . H . S t r o n g G . L . Tingey L . D . Van Hess H . H . Van Tuyl E . J. Wheelwright M. F . W i i t a l a W . R . Wykoff Legal - 703 Bldg Legal - R O B , 2 2 1 - A BNW - T e c h n i c a l

I n f o r m a t i o n ( 5 ) BNW - T e c h n i c a l

P u b l i c a t i o n s (2) FFTF F i l e , 703 Bldg (10) FFTF TPO ( L i s t "T") (3)