Future considerations in the shipment of plutonium

Abstract

Based on t h e data presented, i t i s concluded t h a t h e a t loads and r a d i a t i o n l e v e l s associated w i t h h i g h exposure p l u t o n i u m w i l l r e q u i r e many changes i n f u t u r e s h i p p i n g p r a c t i c e s f o r t h i s t y p e m a t e r i a l s . I n c o r p o r a t i o n o f neutron s h i e l d i n g i n packaging i s expected t o be r e q u i r e d as w i l l r e d e s i g n t o accomodate increased h e a t loads. Moreover, safeguards c o n s i d e r a t i o n s a r e expected t o b r i n g about t h e use o f s p e c i a l l y designed t r u c k s f o r p l u t o n i u m t r a n s p o r t . These t r u c k s w i l l i n c o r p o r a t e s p e c i a l f e a t u r e s t o f u r t h e r h e l p p r e v e n t t h e f t w h i l e i n t r a n s i t . From t h e v i e w p o i n t o f c r i t i c a l i t y safety, l i m i t a t i o n s on f u t u r e packageand t r u c k l o a d i n g s should be no more r e s t r i c t i v e than a t present. I n some instances, c r i t i c a l i t y s a f e t y l i m i t a t i o n s may be r e l a x e d s l i g h t l y by t a k i n g c r e d i t f o r t h e lower f i s s i l e c o n t e n t o f h i g h exposure plutonium. An e s t i m a t e o f how much p l u t o n i u m c o u l d , b e shipped i n a t r u c k , undert h e above mentioned c o n d i t i o n s , was found t o be about 1.5 MT p l u t o n i u m (as Pu02) p e r t r u c k . T h i s q u a n t i t y would r e p r e s e n t about one months product i o n f r o m a l a r g e separations p l a n t .I n t h e more d i s t a n t future, one p o s s i b l e d i r e c t i o n which m i g h t tend t o s i m p l i f y some o f t h e t r a n s p o r t r e l a t e d problems i s t h e n u c l e a r park concept. Under t h i s concept o n s i t e f a c i l i t i e s would preclude t h e t r a n sp o r t a t i o n o f p l u t o n i u m over long d i s t a n c e s . Nuclear r e a c t o r s , t h e separat i o n p l a n t , and t h e fuel f a b r i c a t i o n f a c i l i t i e s , w i t h emphasis on t h e l a t t e r two, would be l o c a t e d on one s i t e and p l u t o n i u m would be t r a n s p o r t e d from one f a c i l i t y t o another w i t h o u t a c t u a l l y e n t e r i n g t h e p u b l i c t r a n s p o r t a t i o n sys tem.

Health physics manual of good practices for plutonium facilities. [Contains glossary]

“…Large masses of plutonium can generally be treated as a point source of neutrons located at the center of the mass if the distance between the center of the mass and the measurement point exceeds the dimensions of the plutonium source array. The neutron dose equivalent rate H (in millirem per hour) at a distance r (in centimeters) from the center of a large mass of plutonium, plutonium oxide, or mixed oxides can be found from Equation (4.6) (Brackenbush, Brown, and Faust 1974):…”