SUMMARY AND INTRODUCTION J . L. M e e m , A s s o c i a t e Physics Division
E. P. B l i z a r d
The L i d Tank F a c i l i t y b a s been a p p l i e d d i r e c t l y i n e x p e r i m e n t s needed t o s o l v e problems o f immediate i n t e r e s t i n the design of the a i r ducts through t h e r e a c t o r s h i e l d of t h e GE-Convair a i r p l a n e (sec. 6 ) . These experiments are e s s e n t i a l , s i n c e the configuration i s so complicated t h a t i t i s p r a c t i c a l l y impossible t o c a l c u l a t e . N e u t r o n and gamma i s o d o s e s a r o u n d m o c k u p s o f t h e GE-ANP i n l e t a n d o u t l e t d u c t s h a v e b e e n obtained. The d a t a o b t a i n e d p r o v i d e the information necessary f o r s p e c i f i In cation of the duct shields. a d d i t i o n , some m e a s u r e m e n t s h a v e b e e n made t o d e t e r m i n e t h e i n d u c e d a c t i v i t i e s around t h e d u c t . The l e a k a g e a r o u n d an a l t e r n a t e ducting arrangement is a l s o b e i n g measured. The Bulk S h i e l d i n g F a c i l i t y ( s e c . 7 ) h a s been a p p l i e d , i n p a r t , t o f u r t h e r a i r - s c a t t e r i n Q e x p e r i m en t s A 1t h o u gh t h e s e e x p e r i m e n t s are n o t y e t conc l ~ ~ s i v ei n , dications are that the e a r l i e r experiments gave doses t h a t were t o o h i g h ; b u t t h e d e s i g n s o f t h e 1950 S h i e l d i n g B o a r d a r e n o t y e t completely vindicated. T h e RSF‘ h a s a l s o been u s e d t o e x t e n d t h e s p e c t r a l and ,d o s e m e a s u r e m e n t s on t h e NEPA d i v i d e d s h i e l d mockup. T h e s e d a t a w i l l now b e u s e d t o improve t h e c a l c u l a t i o n o f t h e d o s e a t t h e crew p o s i t i o n . Additional e x p e r i m e n t s now u n d e r way a t t h e BSF i n c l u d e t h e i r r a d i a t i o n o f a n i m a l s and t h e measurement of t h e energy r e l e a s e p e r u~~~ f i s s i o n .
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T h e Tower S h i e l d i n g F a c i l i t y ( s e c . 8 ) h a s b e e n a p p r o v e d and t h e L a b o r a t o r y is committed t o a s c h e d u l e t h a t c a l l s
for completion o f construction i n Detailed engineering N o v e m h e r 1953. design h a s been c o n t r a c t e d t o the a r c h i t e c t u r a l f i r m o f Knappen, T i p p e t t s , A b b e t t , M c C a r t h y , who h a v e r e v i s e d t h e tower d e s i g n t o e l i m i n a t e c a n t i l e v e r t r u s s e s . T h e new d e s i g n had a s i g n i f i c a n t 1y h i g h e r n e u t r o n s c a t t e r i n g b a c k ground than e a r l i e r d e s i g n s ; conseq u e n t l y , a l t e r n a t e d e s i g n s a r e now being studied. I n i t i a l tests with the completed f a c i l i t y , which w i l l p r o b a b l y make u s e o f t h e G E - C o n v a i r s h i e l d d e s i g n , a r e s c h e d u l e d t o commence i n
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1954.
The n u c l e a r m e a s u r e m e n t ( s e c . 1 0 ) s t u d i e s include an experiment t o determine the angular d i s t r i b u t i o n o f n e u t r o n s s c a t t e r e d from n i t r o g e n a n d a new c a l i b r a t i o n o f t h e f a s t - n e u t r o n dosimeter. The a n g u l a r d i s t r i b u t i o n o f n e u t r o n s was m e a s u r e d by u t i l i z i n g t h e 5-Mev Van d e G r a a f f a c c e l e r a t o r . Analyses of the pulse-height d i s t r i butions of the nitrogen recoils indic a t e a d e f i n i t e change i n the d i f ferential cross section of nitrogen t h a t i s associated with the resonance v a l u e and a n i n c r e a s e i n t h e forward s c a t t e r i n g . The f a s t - n e u t r o n dosimeter was “ c a l i b r a t e d , ” i n a b i o l o g i c a l s e n s e , a t t h e Z e r o Power R e a c t o r a t A r g o n n e N a t i o n a l L a b o r a t o r y by t a k i n g advantage o f a s i t u a t i o n i n which a h i g h f a s t - n e u t r o n d o s e was a c c i d e n t a l l y It was r e c e i v e d by a n i n d i v i d u a l . f o u n d t h a t t h e ZPR l e a k a g e f l u x e s a n d fast-neutron dose readings i n the w a t e r r e f l e c t o r were q u i t e s i m i l a r t o t h o s e e x p e c t e d from a comparison w i t h t h e BSF d a t a .
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