TE C H N I C A L NO T E
Wi t h r e g a r d t o P r o f . K a te B r o w n ’ s o p in io n le t t e r “C a l i f o r n i a ’ s S a n O n o f r e n u c l e a r p l a n t i s a C h e r n o b y l w a i t i n g t o h a p p e n ” ( publ i s hed i n t he L. A . Ti m e s on No v . 1 9 , 2 0 1 9 ) , w e n o t e h e r e t h a t th e a s s o c i a t i o n o f S a n O n o f r e wi t h Ch e r n o b y l i s te c h n i c a l l y i n a c c u r a te a n d g r o s s l y m i s l e a d i n g fo r th e r e a s o n s l i s te d b e l o w .
1) Th e c o n t e x t i s c o m p l e t e l y d i f f e r e n t . S a n O n o f r e i s a sp e n t f u e l st o r a g e f a ci l i t y in t h e U. S . , w h i c h e x p e r i e n c e d a mi n o r mi s h a n d l i n g o f a d r y c a s k in 2 0 1 8 . T h e e v e n t s a t C h e r n o b y l r e p r e s e n t a ma j o r a c c i d e n t and ra d i o a c t i v e re l e a s e at a l a r g e o p er a t i n g r ea c t or in t h e f o r m e r So v i e t U n i o n in 1986 .
2) Sp e n t f u e l i n a d r y c a s k ca n n o t su s t a i n a cr i t i c a l nuc l ea r c hai n r eac t i on . Dr y c a s k s a r e c y l i n d r i c a l c o nt ai ne r s ma d e o f s t e e l a n d c o n c r e t e , e a c h s t o r i n g a f ew doz en el em ent s of s pe nt f uel f r om a nuc l ea r r eac t or . H ow ev e r , a dr y c as k i s not a n uc l ear r ea c t o r . I t w oul d be phy s i c al l y i m p os s i bl e f o r t he s pent f uel i n a dr y c a s k t o s us t ai n a ch a i n r e a c t i o n e ve n i f i t w a s f l o o d e d w i t h w a t e r o r i t s g e o m e t r y w a s ch a n g e d , f o r e xa m p l e , b e c a u se o f a dr op. A s s uc h, a d r y c a s k c a nnot ex pe r i enc e an ex pl os i v e r unaw ay r eac t i on l i k e t he C he r noby l r eac t or , el i m i nat i ng a ma j o r dr i v i n g f o r c e f o r r a d i o a c t i v i ty d i s p e r s a l .
3) Sp e n t f u e l c a s k s c o n t a i n f a r l e s s r a d i o a c t i v i t y t h a n w h o l e r e a c t o r s . Th e r a d i o a c t i v i t y i n v e n t o r y i n t h e s e d r y ca sks i s va st l y l o w e r th a n i n a n o p e r a ti n g r e a c to r b e c a u s e ( i ) e a c h dr y c a s k s t or e s a re l a t i v e l y sm a l l a m o u n t of f uel , and ( i i ) r adi oac t i v i t y nat u r al l y dec ay s ov er t i m e 1 .
4) Dr y c a s k s a r e s p e c i f i c a l l y e n g i n e e r e d t o s t o p l e a k s t h r o u g h m u l t i p l e s a f e t y b a r r i e r s , a n d m i ti g a t e th e co n se q u e n ce s o f a r e l e a s e , sh o u l d a l e a k o ccu r . Th e r e s i d u a l r a d i o a c t i v i t y i s co n t a i n e d w i t h i n se a l ed fu e l ro d s , w h i c h i n t u r n si t wi t h i n t h e d r y c a s k s . T h e c a s k s a r e p r o p e r l y s h i e l d e d t o p r o t e c t wo r k e r s f r o m d i r e c t ex pos ur e t o ex c es s i v e l ev el s o f r adi at i on . S ho ul d t he c as k b e br eac hed , t he r adi oac t i v i t y w i l l s t ay w i t hi n t he fu e l ro d s . S h o u l d t h e re a l s o b e a b re a c h o f o n e o r m u l t i p l e ro d s w i t h i n o n e c a s k , t h e v a s t m a j o ri t y o f ra d i o a c t i v e m a t e ri a l w i l l n o t b e re l e a s e d i n t o t h e e n v i ro n m e n t b e c a u s e i t i s i n th e fo r m o f so l i d ( n o n - vo l a t i l e ) ce r a m i c pel l et s . A s m a l l a m o u n t o f g a s e o u s (v o l a t i l e ) ra d i o a c t i v i t y c o u l d b e re l e a s e d , b u t th e am ount i s s o sm a l l t h a t n o di s c e r nabl e heal t h c ons equen c es a r e ex pec t ed f or t he s i t e w o r k e r s , l e t al one t he gene r al p ubl i c or t he env i r onm en t 2 . T h i s r e m a i n s t r u e w h e th e r o n e i n s p e c ts t h e d r y c a s k s o r not .
5) Th e c a s k s a r e r o b u s t l y d e s i g n e d a n d t e s t e d to w i th s ta n d n o r m a l a g e i n g e f fe c ts a n d c o r r o s i o n ov e r t h e c o ur s e of t hei r l i c ens ed 60 - ye a r l i f e t i m e , a s w e l l a s a b n o r m a l s i tu a ti o n s s u c h a s d r o p fr o m a h e i g h t, e x p o s u r e to fi r e , su b m e r si o n i n w a t e r (a s a re s ul t o f si t e f l o o d i n g f r o m a hy p ot h e t i c a l ts u n a m i fo r e x a m p l e ) , l i g h tn i n g s t r i k e s , ear t hq uak es , t or nadoes , et c . M i n o r c r a c k s and de f or m a t i ons ca n o cc u r o f co u r se , b u t w o u l d n o t r e s u l t i n a si g n i f i ca n t r e l e a se o f r a d i o a ct i vi t y , a s e xp l a i n e d a b o ve .
6) T h e sp e n t f u e l i n t h e d r y ca sk s ca n n o t o ve r h e a t . In fa c t , th e a m o u n t o f h e a t g e n e r a te d b y th e s p e n t fu e l i s s o sm a l l t h a t t h e ca s ks d o n o t n e e d a n y a ct i ve co o l i n g 3 : th e a i r i n c o n ta c t w i th t h e e x te r i o r o f th e c a s k s i s s u ffi c i e n t to k e e p a l l th e m a te r i a l a t a n ac c e pt a b l e t e m p e r at u r e .
7) Th i s i s n o t a n e w t e c h n o l o g y w i t h m a j o r u n c e r t a i n t i e s . T h e o p e r a t o r s o f n u c l e a r p o w e r p l a n ts i n t h e U . S . h a v e been us i ng dr y c as k s f or s pent f uel s t or a ge f o r ov er t w o dec a des . T h ei r s a f et y r ec or d i s o ut s t andi ng . Ha v i n g
1 Fo r e x a m p l e , t h e r a d i o a c t i v e i o d i n e r e l e a s e d f r o m C h e r n o b y l , m e n t i o n e d i n P r o f . B r o w n ’ s o p i n i o n l e t t e r , h a s a h a l f l i f e o f e i gh t day s . T h i s m eans t hat i n a f ew m on t hs , nea r l y al l o f i t nat u r al l y dec ay s aw ay .
2 Th e r a d i a t i o n d o s e a t th e s p e n t fu e l s to r a g e si t e b o u n d a r y f o r a d r y c a sk l e a k a cci d e n t , es t i m at ed unde r c ons e r v at i v e as s um p t i ons is a b o u t 0 . 4 m S v . T h i s i s about t he s am e dos e r ec e i v ed dur i ng t w o r oundt r i p i nt e r c on t i nent a l f l i gh t s , and le s s t h a n a n abdom en X - ra y sca n .
3 Th e d e s i g n h e a t g e n e r a t i o n r a t e i n a d r y c a s k i s le s s t h a n 4 0 k W , a b o ut 1 0 0 , 0 0 0 l o w e r t h a n t h e h e at g e n e r at i o n r a t e i n t h e Ch e r n o b y l r e a c t o r .
sa i d t h a t, i t w o u l d b e d e s i r a b l e to m o v e t h e d r y c a s k s fr o m S a n O n o f r e and ot her per m anen t l y s hu t dow n nuc l ear pl ant s i t es th r o u g h o u t th e U .S . to a l o n g - te r m c e n tr a l i z e d s p e n t fu e l s to r a g e fa c i l i ty , s o th a t s u c h s i te s ca n b e r e t u r n e d t o “ g r e e n f i e l d ” co n d i t i o n s .
T he F ac ul t y o f t he N uc l ear S c i enc e and E ngi neer i ng D e par t m ent
De c e m b e r 6 , 2 0 1 9
Re f e r e n c e s :
U. S . Nu c l e a r Re g u l a t o r y Co m m i s s i o n , Ho l t e c I n t e r n a t i o n a l HI S T O RM 1 0 0 Ca s k S y s t e m , Sa f e t y Ev a l u a t i o n Re p o r t , M L 0 0 3 7 1 1 8 6 5 , M a y 4 , 2 0 0 0 .
Ho l t e c I n t e r n a t i o n a l , Fi n a l Sa f e t y An a l y s i s R e p o r t o n t h e H I - ST O R M U M AX C a n i s t e r S t o r a g e Sy s t e m , R e v . 3 , Ju n e 29 , 2 016.
El e c t r i c Po w e r R e s e a r c h I n s t i t u t e , D r y C a s k S t o r a g e W e l d e d St a i n l e s s St e e l C a n i s t e r B r e a c h C o n s e q u e n c e An a l y s i s Sc o p i n g S t u d y , No v em ber 17, 2017
Fi gur e 1 . S pe nt nuc l ea r f uel in d r y c a s k s is s h o w n h e r e a t t h e C o n n e c t ic u t Y a n k e e n u c le a r pow e r pl ant s i t e . Th i s storage area is all that is left of the now -d ecommissioned nuclear plant, which generated 580 MW of electricity for 21 effective full -p ower years. ( source: http://www.connyankee.com/html/fuel_storage.html )
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Fi gur e 2 . Th e s i t e o f t h e n o w - dec om m i s s i oned M ai ne Y ank ee nu c l ear pow e r pl ant . T he s i t e h as been r et u r ned t o “g r e e n f i e l d ” c o n d i t i o n s w i th th e e x c e p ti o n o f th e s p e n t f uel dr y c as k s , w hi c h ar e st o r e d i n o p e n a i r w i t h i n th e sm a l l w e l l - fe n c e d a r e a sh o w n i n t h i s p i c t u r e . (s o u rc e : B a n g o r D a i l y N e w s )
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Fi gur e 3 . Dr y c a s k s c o n t a i n i n g s p e n t n u c l e a r f u e l a r e i n s p e c t e d a t a n u n s p e c i f i e d U . S . nu c l ear p ow er pl ant . T he c a s k des i gn i nc l udes r adi at i on s hi el di ng, s o t ha t app r oac hi ng and handl i ng t he s e c as k s e x pos es t he w or k e r s t o a negl i gi bl y lo w r a d ia t io n d o s e . ( s o u r c e : N u c le a r E n e r g y I n s t it u t e )
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Fi gur e 4 . MI T nu c l ear s c i enc e and engi neer i ng f ac ul t y an d st u d e n t s vi si t in g th e sp e n t f u e l dr y - ca sk s t o r a g e f a ci l i t y a t th e P i l g r i m n u c l e a r p o w e r p l a n t i n P l y m o u th , Ma s s a c h u s e t t s . ( S o u r c e : M I T )
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Fi gur e 5 . Hi g h wa y P a t r o l O f f i c e r s c o n d u c t r a d i o l o g i c a l s u r v e y s o n t h e f i r s t Ne v a d a T e s t S i t e t r a n s u r a n i c wa s t e shi pm ent a t t he A r ea 5 R a di oac t i ve W a st e M anagem en t C om pl ex l oc at ed o n t he N ev ada T es t S i t e . Th e s e s h i p m e n t s tr a v el on n o r m a l publ i c r oads to thei r fi nal de s ti na ti on a t the W as te P i l ot Is ol a ti on P l ant nea r C a r l s bad, N ew M ex i c o . (source: NNSA)
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