ucrl 5124 phenomenology of contained nuclear explosions

8/7/2019 ucrl 5124 Phenomenology of Contained Nuclear Explosions

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PHENOMENOLOGY OF CONTAINED NUCLEAR EXPLOSIONS

L I V E R M O R E S I T E


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DISCLAIMER

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


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DISCLAIMER

Portions of this document may be illegible inelectronic image products. Images are producedfrom the best available original document.


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U C R L - 5 1 2 4 R e v . I

U N I V E R S I T Y O F C A L I F O R N I AL a w r e n c e R a d i a ti o n L a b o r a t o r y

L i v e r m o r e , C a l i f o r n i aC o n t r a c t N o . W - 7 4 0 5 - e n g - 4 8

P H E N O M E N O L O G Y O F C O N T A I N E D N U C L E A R E X P L O S I O N SG e r a l d W . J o h n s o n an d C h a r l e s E . V i o l e t

D e c e m b e r 1 9 5 8

P r i n t e d f o r t h e U . S . A t o m i c E n e r g y C o m m i s s i o n


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- 2 - UCRL-5124 Rev. I

PHENOMENOLOGY OF CONTAINED NUCLEAREXPLOSIONS*

Gerald W. Johnson and Charles E. Violet

University of CaliforniaLawrence Radiation Laboratory, Livermore, California

December 1958

I. INTRODUCTIONOn September 19, 1957, the first completely contained nuclear ex

plosion was fired at the Nevada Test Site. The results of this explosion12 3 4as w ell as its significance have been discussed in considerable detail. ' ' 'The explosion had an energy release equivalent to 1700 tons of high explo-

9sive. Since one ton is defined as 10 calories the total energy release12

was 1. 7X10 calories. During the month of October, 1958, several additional underground shots were detonated at various scaled depths withenergy releases from about 100 tons to more than 20 kilotons. In this paper the phenomenology of the first explosion, code name "Rainier", willbe discussed, as it is now understood. In addition, the gross results ofthe jnore recent explosions will be given.

II. THE RAINIER EVENTThe Rainier detonation took place in a room 6 ft x 6 ft x 7 ft at the

end of a tunnel driven into the side of a mountain. The vertical depth ofburial was 899 ft and the distcince to the nearest point on the sloping face

/ 1/3 790of the mountain was 790 ft. The scaled depth is given by D/W ' = TT%~663 ft. D is the actual depth in feet and Wthe energy release in kilotons. 5

The geology of the mountain as determined by the USGS is characterized by a cap of welded tuff about 250 ft thick which is underlain byseveral layers of bedded tuffs to a depth of about 2, 000 ft. The basement _ .

This report is based on a joint paper given at the Fourth Annual Symposium on Mining Research held at Rolla, Missouri, Nov. 13, 1958. Thework was performed under the auspices of the U.S. Atomic Energy Commission.


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- 3 - U C R L - 5 1 2 4 R e v . Ir o c k i s d o l o m i t e . T h e t uf fs v a r y f r o m u n c o n s o l i d a t e d t o c o n s o l i d a t e d . T h et u n n e l i t s e l f w a s i n a c o n s o l i d a t e d b e d s o t h a t n o s h o r i n g w a s r e q u i r e d .T h e t u n n e l s e c t i o n w a s a b o u t 7 ft x 8 f t . T h e g e o l o g i c a l s t r u c t u r e a n d t h eloc a t i o n of t he s ho t po in t w i th r e s p e c t t o t he s u r f a c e i s s how n in F ig . 1 .T h e a v e r a g e p r o p e r t i e s of t h e m e d i u m s u r r o u n d i n g t h e p o i n t of d e t o n a t i o n a r e l i s t e d i n t h e f ol lo w in g s e c t i o n s : T h e p h y s i c a l p r o p e r t i e s l i s t e da r e i n t e n d e d t o r e p r e s e n t o u r b e s t e s t i m a t e s of t h e a v e r a g e p r o p e r t i e s oft h e m e d i u m w i t h i n 10 0 ft of t h e c e n t e r of d e t o n a t i o n . T h e s a m p l e s w e r ea l l c o l l e c t e d i n t he v i c in i t y o f t he po in t of de t on a t i o n p r i o r t o t he s h o t . T hem a g n i t u d e s o ft en r e p r e s e n t a v e r a g e s of m i e a s u r e m e n t s m a d e b y v a r i o u s6g r o u p s .D e n s i t y :B u l k d e n s i t y i n s i t u

B u l k d e n s i t y d r yW a t e r c o n t e n t b y w e i g h tP o r o s i t yG r a i n d e n s i t yM o s t of t h e w a t e r c o n t a i n e d i n t h e r o c k i s r e l e a s e d b y h e a t i n g t o

l l O ^ C . A t t h i s t e m p e r a t u r e 8 0 % of t h e w a t e r i s r e l e a s e d , b y h e a t i n g t o6 0 0 ' 'C a n o t h e r 1 8 % i s r e l e a s e d , a n d a b o u t 2 % m o r e b y h e a t i n g t o 1 0 0 0 C .B u l k M o d u l u s :

T h e m e a s u r e m e n t w a s m a d e a t 25 "'C a n d i n t h e p r e s s u r e r a n g e 0 -5 0 00 p s i . T h e m o d u l u s a s m e a s u r e d f o r j a c k e t e d s a n n p l e s w a s t h e s a m ef o r bo th d r y a nd s a tu r a t e d t uf f a nd i s 3 . 5 x 10 dy ne s / c na S p e c i f i c H e a t :

T h e s pe c i f i c he a t f o r t he d r y r oc k in t he r a n ge of 25 C to 600 ' ' C a ndf o r ^wet r o c k i n t he r a ng e 25 C to 100 C w as c a l c u l a t e d f r o m th e c h e m ic a lc o m p o s i t i o n .

D r y R o c kT e m p e r a t u r e 2 5 C 1 0 0 C 2 0 0 C 4 0 0 ' ' C 6 0 0 CS p e c i f ic h e a t : 0 . 1 8 0 0 . 2 1 1 0 . 2 3 6 0 . 2 7 2 0 . 3 0 0C c a l / g / - C |

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- 5 - U C R L - 5 1 2 4 R e v . IS a t u r a t e d R o c k

T e m p e r a t u r e : 2 5 '' C 100CSp ec i f ic he a t : 0 . 30 0 . 32( c a l / g / ' - C )S p e c i f i c h e a t f o r s a t u r a t e d r o c k d o e s n o t i n c l u d e h e a t of v a p o r i z a t i o n .C h e m i c a l A n a l y s i s ( F r a c t i o n b y d r y w e i g h t ) ;

S i O ^ - 76%A l ^ O ^ - 13%F e O j - 1 . 5 %

F e O - 0 . 0 5 %N a ^ O - 2 . 0 %

C o m p r e s s i v e S t r e n g t h :3, 5 - 7 . O x 10 d y n e s / c m

T h e r m a l C o n d u c t i v i t y ( a t 2 9 . 0 0 . 3 C ) :3D e h y d r a t e d K = 1 . 70 x 1 0 " c a l / c m s e c C

S a t u r a t e d K = 2 . 6 0 x 1 0 " c a l / c m s e c ' CS o u n d V e l o c i t y ( m e a s u r e d i n s i tu ) :

5 / 2 . 4 X 10 cm i /s ecP e t r o g r a p h y :

T h e r e i s a m a r k e d s i n a i l a r i t y in a l l tu ff s a m p l e s t a k e n fro m i t h i s r e g i o n of t h e N e v a d a T e s t S i t e . T h e p r e d o m i n a n t c o n s t i t u a n t i s a m a t r i x off i n e - g r a i n e d z e o l i t e s i n c lu d i n g h e u l a n d i t e , c r i s t o b a l i t e an d m o n t m o r i l l o n i t e .L e s s t h a n 1 0 % b y v o l u m e i s r e p r e s e n t e d a s p h e n o c r y s t s , m a i n l y a l k a l i n ef e l d s p a r .F u s i o n T e s t s :

C o n e s p r e p a r e d f r o m c r u s h e d s a m p l e s w e r e h e a t e d in a f u r n a c e . A l lde f o r m e d i n t he r a ng e 1280 - 1300C . O n a c c ou n t o f t he l a r g e g l a s s c o n t e n t n o g r e a t v o l u m e c h a n g e w o u l d b e e x p e c t e d o n f u s i n g .

T h e t u n n e l w a s t e r m i n a t e d i n a s p i r a l ( F i g . 2 | d e s i g n e d b y G . T . P e l s o8a n d B . S u s s h o l z of s u c h d i m e n s i o n s t h a t i t w a s e x p e c t e d t o s e a l i t s e l f b yc o l l a p s e b e f o r e a n y r a d i o a c t i v e d e b r i s c o u l d p r o j e c t a r o u n d t h e s p i r a l ctndo u t t h e t u n n e l . P r i o r t o t h e d e t o n a t i o n , t h e r e w a s c o n s i d e r a b l e c o n c e r n

K ^ O - 5 . 0%M g O - 0 . 5 %CaO - 1%C O ^ - 0 . z%


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~ 7 ~ U C R L - 5 1 2 4 R e v . It h a t r a d i a l f r a c t u r i n g e i t h e r t o t h e t u n n e l o r t h e s u r f a c e m i g h t p r e v e n t c o n t a i n m e n t of t h e r a d i o a c t i v e p r o d u c t s by t h i s s i m p l e d e s i g n .

I I I . R E S U L T S F R O M T H E R A IN I E R E V E N TT h e R a i n i e r d e v i c e w a s d e t o n a t e d a t 0 9 h r 5 9 m i n 5 9 . 4 5 s e c . P a c i f i c

d a y l i g h t t i m e , o n S e p t e m b e r 1 9 , 1 9 5 7 . T h e c o o r d i n a t e s of t h e c e n t e r ofd e t o n a t i o n w e r e L a t . N 3 7 " 1 1 ' 4 4 . 8 0 " , L o n g . W 1 1 6" 1 2 ' 1 1 . 3 5 " , a n d t h ee l e v a t i o n w a s 6 6 1 1 f t .

F r o m t h e f i ri n g p o i n t a t 2 . 5 m i l e s f ew p e o p l e f e lt a n y g r o u n d s h o c k .S o m e h e a r d a n nu ffle d b o o m . S c a t t e r e d r o c k s w e r e s h a k e n l o o s e f r o m t h ec a p r oc k o f t he h i l l f o r d i s t a nc e s o f a bou t l / 2 nn i l e e a c h s i de o f t he po in to f d e t o n a t i o n .I n s p e c t i o n of t h e t u n n e l a f t e r t h e s h o t r e v e a l e d t h a t c o l l a p s e of t h et u n n e l h a d o c c u r r e d a t a r a d i a l d i s t a n c e o f 2 00 ft a n d t h a t s p a l l i n g h a d c o n t i n u e d t o a b o u t 4 0 0 f t. B e y o n d t h a t d i s t a n c e t o t h e p o r t a l , e x c e p t f o r o c c a s i o n a l s p a l l i n g t h e r e w a s n o d a n a a g e . T h e t o t a l a m o u n t of s p a l l e d m a t e r i a l be y ond 400 ft a m ou n te d t o a f e w c ub i c y a r d s . A t 1100 f t f r o m thec en te r o f de ton a t i on th e re w^as a sh i f t a long a bed din g p l an e of abo ut 0 . 35f t .

A s f a r a s c o u l d b e d e t e r n n i n e d , t h e r a d i o a c t i v i t y w a s c o m p l e t e l yc o n t a i n e d , a l t h o u g h s m a l l l e a k s t o t h e s u r f a c e c o u l d h a v e e v a d e d d e t e c t i o n . N o n e w a s d i s c o v e r e d i n s i d e t h e t u n n e l i n e x c e s s of n a t u r a l b a c k g r o u n d ( 0 . 0 4 m r / h r ) a s m e a s u r e d p r i o r t o t h e e x p l o s i o n , A s e a r c h u s i n gt h e m o s t s e n s i t i v e r a d i o c h e m i c a l t e c h n i q u e s w a s m a d e f o r r a d i o a c t i v ei s o t o p e s of t h e r a r e g a s e s , k r y p t o n a n d x e n o n . T h e c o n c e n t r a t i o n s oft h e s e g a s e s w e r e b e l o w t h e l i m i t s of d e t e c t a b i l i t y , n a m e l y 1 x 10 f i s -s i o n / f t . I t i s b e l i e v e d t h a t n o l e a k of a c t i v i t y o c c u r r e d t o t h e s u r f a c e ;h o w e v e r , s m a l l l e a k s na ig h t n o t h a v e b e e n d e t e c t e d d ue t o h i g h b a c k g r o u n d(2 0 m i l l i r o e n t g e n s / h r ) f r o m p r e v i o u s a i r b u r s t s .A c c e l e r a t i o n a n d d i s p l a c e n a e n t n a e a s u r e m e n t s b y t h e S t a n f o r d R e s e a r c h I n s t i t u t e , E d g e r t o n , G e r m e s h a u s e n an d G r i e r , I n c . , a n d S a n d i aC o r p o r a t i o n ' ' i n d i c a t e d t h a t d i r e c t l y a b o v e t h e p o i n t of d e t o n a t i o nt h e s h o c k a r r i v e d a t 14 6 n a s a n d t h e m a x i i n u m v e r t i c a l e x c u r s i o n w a s 9i n . T h e v e r t i c a l d i s p l a c e m e n t a t h o r i z o n t a l r a d i i of 1 00 0 ft f r o m a p o i n t


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- 8 - U C R L - 5 1 2 4 R e v . Io n s u r f a c e d i r e c t l y a b o v e t h e d e t o n a t i o n w a s l e s s t h a n l / 2 i n . A n a l y s i s ofa l l r e s u l t s i n d i c a t e d t h a t a b l o c k a b o u t 1 00 - 2 00 ft t h i c k s e p a r a t e d a n dr o s e a nd f e l l a s a u n i t . T h e m a x i m u m a c c e l e r a t i o n o n t h e s u r f a c e w a s5 . 8 g a t 1 86 m s a n d t h e m a x i m u m d i s p l a c e m e n t of 9 i n . o c c u r r e d a t 3 5 0 m s .R a i n i e r s e i s m i c ef f e ct s w e r e m e a s u r e d b y U . S . C o a s t a n d G e o d e t i c12 5S u r v e y a n d t h e U . S . G e o l o g i c a l S u r v e y . S e i s m i c s i g n a l s w e r e d e t e c t e da t v a r i o u s s t a t i o n s i n t h e c o n t i n e n t a l U . S . a n d a t d i s t a n c e s u p t o 1 00 0 m i l e s .S e i s m i c s i g n a l s w ^ere a l s o d e t e c t e d ( t h o u g h b a r e l y r e s o l v e d ) a t C o l l e g eS t a t i o n i n F a i r b a n k s , A l a s k a a t a d i s t a n c e of 22 00 m i l e s .

I V . P H E N O M E N O L O G Y O F T H E R A I N I ER E V E N TF r o m a n a n a l y s i s of c o r e s o b t a i n e d f r o m d r i l l h o l e s i n t o t h e R a i n i e rz e r o s i t e a s iw ell a s m e a s u r e m e n t s m a d e in t h e s e h o l e s , t h e s e q u e n c e of

e v e n t s i m m e d i a t e l y foUo^s^ing t h e e x p l o s i o n c a n b e r e c o n s t r u c t e d . T h ei n i t i a l c o n d i t i o n s i n t h e z e r o r o o m c a n b e c a l c u l a t e d a s f ol lo w ^s :

. 4n - 'T '4E n e r g y d e n s i t y : E = E + E = 3 / 2 n k T +w h e r e E = e n e r g y d e n s i t y i n t h e p a r t i c l e s

E = e n e r g y d e n s i t y i n r a d i a t i o nn = -rr = n u m b e r of p a r t i c l e s p e r c m

k = 1 . 37 X 10 e r g / K ( B o l t z n a a n n ' s c o n s t a n t )T = T e m p e r a t u r e K- 5 / 2 / 4(T = 5 . 74 X 10 e r g / c m /"K ( S t e p h a n - B o l t z m a n nc o n s t a n t )c = 3 x 1 0 c m / s e c ( v e l o c i t y of l ig h t )2 3A = 6 . 0 3 X 10 ( A v o g a d r o ' s n u m b e r )

M = m o l e c u l a r w e i g h tp = d e n s i t y i n g / c m

This can be pu t in the fo rnaE = 3 / 2 ^ k T + i ^

= 1 . 25 x 1 0 ^ ^ T + 7 . 6 5 X 1 0 " ^ ^ T ^ e r g / c m ^T h e p r e s s u r e e q u a l s 2 / 3 p a r t i c l e e n e r g y d e n s i t y p l u s l / 3 r a d i a t i o n

e n e r g y d e n s i t y , t h u sP = 0 . 8 3 x 1 0^ ^ T + 2 . 5 5 x l O " ^ ^ T ^ d y n e s / c m ^


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- 9 - U C R L - 5 1 2 4 R e v . IK n o w l e d g e of t h e e n e r g y r e l e a s e , v o l u m e a nd m a s s of m a t e r i a l i n

t h e z e r o r o o m e n a b l e s th e c a lc u l a t i o n of i n i t ia l t e m p e r a t u r e a n d p r e s s u r e .19T h e e n e r g y r e l e a s e o f t h e e x p l o s i o n w a s 7 . 2 x 10 e r g s ( o n e k i l o -12 7 19ton r e l e a s e s 10 x 4 . 2 x 10 = 4 . 2 x 10 e r g s ) . S inc e t he m a s s of m a -6 6 3t e r i a l i n t he r o om w a s a bou t 10 g ( 1 t on ) a nd t he vo lum e w a s 7 x 10 c m ,2t h e m e a n d e n s i t y w a s 0 , 14 g / c m . A t t h e s e e x t r e m e l y h i g h t e m p e r a t u r e s

e s s e n t i a l l y a l l e l e c t r o n s a r e s t r i p p e d fro nn n u c l e i a n d s i n c e t h e a t o m i cw e i g h t i s a p p r o x i m a t e l y tw i c e t h e a t o m i c n u m b e r , t h e e f fe c t iv e m o l e c u l a rweight is given by: S N . x 2 Z .^ e f f * S N ' ( Z . + ' I ) * ^1 1w h e r e N . = n u m b e r of a t o m s of a t o m i c n u m b e r Z . .

1 1T h e s u m m a t i o n i s t a k e n o v e r a l l a t o m s i n t h e z e r o r o o m . T h e r e f o r e , o n ec a n c a l c u l a t e t h a t a t t h e t i m e th e e n e r g y w a s d i s t r i b u t e d i n t h e r o o m t h et e m p e r a t u r e w^as a b o u t 1, 0 0 0 , 0 0 0 ' 'K a n d t h e p r e s s u r e 7 , 0 0 0 , 0 00 a t m o s p h e r e s ( b a r s ) . T h e r a d i a t i o n p r e s s u r e a t t h i s t e m p e r a t u r e is 250 0 b a r sw h i c h i s n e g l i g ib l e c o m p a r e d w it h t h e p a r t i c l e p r e s s u r e .

T he s ho c k f o r a bou t t he f i r s t t h r e e f e e t w a s s u f f i c i e n t l y s t r on g t ova po r i z e t he r oc k , a nd t o m e l t i t ou t t o 15 f t . T h e r o c k w a s c r u s h e d ou tt o a r a d i u s of a b o u t 130 f t. F r o m t h e t i m e of a r r i v a l m e a s u r e m e n t s a n dt h e e q u a t i o n of s t a t e of t h e m e d i u m , t h e p r e s s u r e v s d i s t a n c e c a n b e c a l -7 13c u l a t e d * a nd i s g iv e n i n F ig . 3 .

A s t h e s h o c k m o v e d o u t w a r d , t h e r o o m e x p a n d e d s p h e r i c a l l y a n dr e a c h e d a r a d i u s of 5 5 ft i n s e v e r a l m i l l i s e c o n d s . A t t h i s t i m e t h e c a v i t yw a s l i ne d w i th a bou t 4 i n . of m e l t e d r o c k ( t ha t w h ic h w a s i n i t i a l l y c on t a i ne d i n a s p he r e o f r a d i u s 15 ft a bou t t he c e n t e r of de to na t i o n ) a t a t e m p e r a tu r e of 1200 - I S O O ^ C . T h e de s c r i p t i o n of t he s t a t e of t he c a v i t y a tt h e s e t i m e s a n d t h e m e c h a n i s m s of i t s c o l l a p s e a r e g i v e n i n d e t a i l b y2K e n n e d y a n d H i g g i n s . T h e c a v i t y w h e n f i r s t f o r m e d w a s f i l l e d w i t hs t e a m a t a p r e s s u r e o f 4 0 a t m o s p h e r e s w ^hich i s a p p r o x i m a t e l y t h e l i t h o -s t a t i c p r e s s u r e . T h e c a v i t y s to o d l o n g e n o u g h , b e t w e e n 30 s e c a n d 2m in , f o r m u c h o f t he fl u id r o c k t o f low dow n the s i d e s a n d t o d r i p f r o mth e roof. A t t h i s t i m e t h e c a v i t y b e g a n t o c o l l a p s e a n d t h e c a v i t y c o o l e dr a p i d l y d u e t o e x p a n s i o n of t h e s t e a m q u e n c h i n g s o m e of t h e d r o p l e t s ofr o c k in f r e e f a l l , a s -w ell a s s o m e of t he " i c i c l e s " a s t he y hung s u s p e n de d


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- 1 1 - U C R L - 5 1 2 4 R e v . If r o m t h e c a v i t y roof. S e e F i g . 4 . T h e c a v i t y w a s f i l l e d w i t h b r o k e n r o c kf r o m t h e c o l l a p s e , a n d t h e c a v i ng p r o g r e s s e d s u c c e s s i v e l y v e r t i c a l l y t oa d i s t a nc e of 386 ft a bov e t he po in t of de ton a t i o n . B e c a u s e of t he p r e s e n c eof w a t e r a n d t h e l a r g e p e r m e a b l e r e g i o n p r o d u c e d b y t h e c o l l a p s e d c a v i t y ,t h e m e l t e d r o c k r a p i d l y c o o l e d t o t h e t e m p e r a t u r e of b o i l i n g w a t e r 9 3 C( 6600 ft a l t i t ud e ) . A l l of t he r oc k w h ic h w a s i n i t i a l l y m e l t e d c on ve r t e d t o ag l a s s o n c o o l i n g . T h e g l a s s w a s f o un d t o c o n t a i n a l l of t h e r a d i o a c t i v ef i s s i o n p r o d u c t s e x c e p t t h e r a r e g a s e s . T h e s e q u e n c e of e v e n t s i n t h e c o l l a p s e of t h e c a v i t y i s i l l u s t r a t e d in F i g . 5 .

T h e m o d e l d e s c r i b e d h e r e i s b a s e d o n d a t a f r o m o n e d r i l l h o l e f r o mt h e s u r f a c e v e r t i c a l l y d o w n w a r d t h r o u g h t h e r e g i o n of t h e d e t o n a t i o n a n df r o m t h r e e c o r e d h o l e s f r o m w i t h i n t h e t u n n e l . D r i l l i n g v e r t i c a l l y r e v e a l e dn o r a d i o a c t i v i t y u n t i l t h e d r i l l b r o k e t h r o u g h i n t o a 2 5 - f t - h i g h c a v i t y a t ad e p t h of 5 1 6 ft ( F i g . 5 ) . T h e d i m e n s i o n s o f t h e c a v i t y w e r e n o t m e a s u r e dbu t pho tog r a phs t a ke n i n s ide t he c a v i t y i nd i c a t e d r ough ly a c one w ^ i th ahe igh t of 25 f t . F r o m th i s po in t dow n to t he c e n t e r of de to na t i on , t he r o c kw a s b r o k e n a n d p e r n a e a b l e a s i n d i c a t e d b y t h e f a i l u r e t o r e c o v e r c o r e s a n dt h e l o s s of d r i l l i n g w a t e r . H e r e f o r t h e f i r s t t i m e , a r a d i o a c t i v e i s o t o p eof k r yp ton ( K r ) w a s de t e c t e d ( 5 - 9 x 10 f i s s i o ns / f t ) . T h e a c t i v i t y on t hes o l i d m a t e r i a l w^as ""lO f i s s i o n s / c u f t . B o t h t h e s e l e v e l s a r e m a n y o r d e r sof m a g n i t u d e b e l o w a c c e p t a b l e t o l e r a n c e l e v e l s . D r i l l i n g r a d i a l l y f r o m t h et u n n e l a t d i f f e re n t e l e v a t i o n s r e v e a l e d a c r u s h e d i m p e r m e a b l e z o n e f r o ma r a d iu s of 130 ft t o 55 ft a nd a p e r m e a b l e r e g io n w i th in t he 55 - f t r a d iu s .F i g u r e 6 s ho ve s t h e o r i e n t a t i o n of t h e u n d e r g r o u n d d r i l l h o l e s . 14, 15L o g g i n g t h e d r i l l e d h o l e s f o r t e m p e r a t u r e a n d r a d i o a c t i v i t yg a v e t h e r e s u l t s s h o w n i n F i g . 7 a n d 8 . F r o m t h e f a c t s t h a t t h e r a d i o a c t i v i t y s e e m s t o b e c o n c e n t r a t e d i n a b o w l - s h a p e d s h e l l of r a d i u s of a b o u t5 5 f t, t h a t t h e t e m p e r a t u r e t e n d s t o e q u a l i z e w i t h i n t h a t r a d i u s , a n d t h a td r i l l i n g w a t e r w a s l o s t w i t h i n t h a t r a d i u s , i t w a s c o n c l u d e d t h a t t h e i n i t i a lc a v i t y r a d i u s w a s 5 5 f t .

R a d i o c h e m i c a l a n a l y s i s of t h e g l a s s a n d t h e s u r r o u n d i n g m e d i u ms ho-w e d t ha t a lm os t a l l t he a c t i v i t y w^as t r a p pe d i n t h i s h igh ly i n s o lu b l e

T h e a d v i c e a n d a s s i s t a n c e of L . E . S h a f f e r , U n i v e r s i t y of C a l i f o r n i a ,B e r k e l e y , i n t h e p o s t s h o t d r i l l i n g p r o g r a m i s g r a t e f u l l y a c k n o w l e d g e d .


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