E. Ottewitte - Cursory First Look at the MCFR

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Cursory i r s t Look t t heMol t en hl or i de Fast React or

s l t ernat i ve t o t he onvent i onal BATR Concept

Er i c Ot t ew t t e

pr i l 99



STR CT

I NEL i s present l yst udyi ngt he desi gn and f e a s i b i l i t yof a r o d ppl i cat i on_ Te s t i ngReact or BATR whi ch woul d event ual l y repl acet he dvanced Test React or ATR at I NEL Mol t enChl or i de as t React or MCFR concept w t h t very f a s tneut r on spectrumi n an annul ar core woul dengender hi gh neut r onf l u x e s dr i vi ngi nner nd out er t her mal neut r on f l u xt r a p s each va r i a bl ei n s i z e nd neut r on energy spectrum Cont i nuous processi ngand refuel i ngwoul d m n i m z e r eact or downt i me

bsence of f u e l el ement s and associ at ed s t r u c t u r e sshoul d maxi m ze t e s t space nd f a c i l i t a t eaccesst h e r e t o

Thi s paper col l at es f or t yyears of wor l dw de exper i ence w t h mol t en s a l t r e a c t o r scompi l i ngt he uni que pl uses and m nuses of such reactor I n addi t i on t reports advi ce of co member s of acurrent i nt e r n at i o na lmol t en s a l tconsor t i um



SUMM RY

Techni cal and Economc F e a s i b i l i t yFast mol t en chl ori de r e a c t o r shave been c u r s o r i l yconsi der ed bef or e but mai nl y f or t he U u

f u e l cycl e The ORNL MSR pr ogr amshowed t he f e a s i b i l i t yof f ue l s a l t ci rcul at i on The combi nat i onof tha t exper i ence and M FR research o u t - o f - p i l eexper i ment s and t h eor e t i c al s t udi es ,so f a r pr ovi dea b as i sf or bel i evi ng the concept wi l l work

Chem cal s t a b i l i t yand cor r osi on of mol t en s a l t sar e f a i r l ypr edi ct abl e Low vapor pressure oft he s a l t senhances saf et y and permts l owpressure s t r u c t u r a lcomponent s

Mol t en fue l s t a t e and external cool i ng si mpl i f y component desi gn i n a r a di at i onenvi r onment

They f or ego compl i cat ed ref uel i ng mechani sm cl ose t ol erances associ ated w t h s o l i df u e l ,andmechani cal control devi ces Mol t en s t a t e and l ow vapor pressure of t he s a l t s al s o of f e ri nher ent s a f e t yadvant ages

Gr aphi t e and Mo al l oys and coat i ngs appear as pr om si ng candi dates f or pr i mar y s a l tcontai nment, both i n and out of core These hi gh t emper at ure materi al s may permt hi gh fue l s a l tt emper at ures above 1000°C) Thi s can reduce fue l s a l t i nvent or y i n t he heat exchanger and al l owgast urbi ne cycl es and/ or pr ocess heat a p p l i c a t i o n susi ng hel i umas an i nt er medi at e and f i n a lcool ant

Key M FR dvantages

Soms al i en t

advant ages of t heM FR

concept ar e

Si mpl i ci ty no cont r ol r ods , f uelhandl i ng mechani sms, fue l el ements or associ ateds t r u c t u r e s Ver y uncl ut t ered shoul d maxi m ze t e s t space and f a c i l i t a t eaccess t h e r e t o Fl ui dfue l can be t ransf er red r emotel y by pumpi ng t hr ough pi pes connect i ng storageand reactor

2 MSRs don t r e f u e lor r r r oc e s s ,j u s t add f u e l and pr ocess out wast es Cont i nuouspr ocessi ng and ref uel i ng woul d m ni m z e reactor downt i me Can usef ul l y consume al lfue l f orms, si mpl i f yi ngf ue l suppl y whi l e si mul t aneousl y sol vi ng ot her peopl e spr obl ems

3 MSR s t he sa fes t concept of al l due t o very strong negati ve t emperat ur e c o e f f i c i e n t

No gaseous hydr ogen can possi bl y evol ve f r o mf u e l or pr i mar y cool ant Fuel al r eadymol t en and handl ed by system Si mpl e desi gn t echni que makes boi l i ng i mpossi bl e

Cont i nuous r emoval of f i s s i o npr oduct s r educes t h e i rheat source by t wo orders ofmagni t ude consequent l y, natural c i r c u l a t i o ns uf f i ces f oremer gency cool i ng, therebygr e at l yr educi ng t he desi gnat ed evacuati on area Al so, under any of f - normalcondi t i ons, t he l i q u i dfue l can be channel ed t o a cont i nuousl y cool ed drai n t a n k , i n asho r t t i me

Very f as t neut r on spectr um i n an annul ar cor e engenders hi gh neut r on f l ux es ,dri vi ngi nner and out er t her mal neut r on f l u x t r aps , each var i abl e i n s i ze and neutron energyspectrum by means of mol t en s a l t composi t i on El i mnat i on

of f ue l cl addi ng and



s t r u c t u r a lmat eri al s i g n i f i c a n t l yi mpr oves t he neutr on economy of t he reactor mor eneutr ons ar e avai l abl e f or appl i cati ons

El i m nat i onof pressur i zedand pr essur e- evol vi ngcomponent s i n s i d et he cont ai nmentr educi ngr i s kof cont ai nment f a i l u r e

6 Pot ent i al addi t i onal m ssi ons f or an MCFR B TR coul d i ncl ude

a Sr and Cs wast e t r ansmut at i on because of very hi gh neut r onf l u x

b Usef ul consumpt i on of f i s s i l ef u e l f r o mdi smant l ed weapons because of t hef l e x i b i l i t yi n f u e l f o r m

c Process heat R D due t o hi gh t emperatur ecapabi l i ty

d Li D or Li OD s he l l f or gener at i on of a 14 MeV f usi on neutron t r a p

I nher ent D sadvantages and Li m t at i ons t o MCFRs

Expect ed pr obl emareas and concer ns f or an MCFR w i l lbe tha t

Ext ernal cool i ng and l o c al pr ocessi ng pr oduce hi gh f u e l i nvent or y i n- p l a nt; on t heot her hand l t t l i nvent or y e x i s t sout - of - pl ant or i n t r a n s p o r t

Mol t en s a l t fu e l t r a n s f e r sheat poor l y compar ed w t h sodi umi n an LMFBR

3 The hi gh mel t i ngpoi nt ~ 560°C of s u i t a b l efu e l s a l t sn ec e s s i t a t e spr eheat i ng i n manypl aces

The hi gh mel t i ngpoi nt of t he f u e l s a l t l i m t st he At across a heat exchanger l e s s t hes a l t freeze Consequent l y one must i ncrease t he mass f l o wr a t e

5 The pr esence of f i s s i o npr oduct s i n t he fu e l s a l t n ec e s s i t a t e sa hi gh standar d of p l a ntr e l i a b i l i t yand l eak t i ght n es s

6 Cor r osi on and hi gh t emper at ure l i m t t he choi ce f or s t r u c t u r a lmateri al s

7 H gh neutr on f l u xdamages s t r u c t u r a lmateri al s

8 The pr ocessi ng pl ant r e qui r e sdevel opment s

9 Mut ant s i n t he f u e l s a l t i nc l udi ngs ul f u rf r o mchl ori nemut at i on corrode

L i m t s on power densi t y may come f r o m

Radi at i ondamage t o t he hi gh f l u x

H gh t emper at ure of t he fu e l cool ant causi ng l eakage t hr ougha seal expansi on mel t i ng



of met a l , or chem cal cor r osi on

3 Hi gh f u e l i nvent or y i n t he heat exchanger , a f f e c t i n geconom cs, doubl i ngt i me, and

reactor control

se of repl aceabl e graphi t ef or t he materi al i n cont act w t h t he f ue l cool ant t hr oughout t he reactor andmu of t he pri mary c i r c u i tm ght el i m nate mu of concer ns 1 nd 2



CONTENTS

STR CT

SUMM RY v

Techni cal and Economc eas i b i l i t y v

Key MCFR Advant ages v

I nherent Di sadvantages and Li mtat i ons t o MCFRs v i

I NTRODUCTI ON

TRREQU REMENTS

NDMSSI ONS

2

Requi r ement s of a BATR Concept 2

M ssi ons

GENER L MOLTEN SALT REACTORS 3

Physi co Chemcal Features 3

P e r i t e c t i cmel t i ng poi nt 3

Flui d Fuel Features 4

Ther mohydr aul i c Advant ages 4

Ext ernal Cool i ng 5

Cont i nuous On Li neProcessi ng 5

React or Safety 6

Leakage of Radi oacti ve S al t 7

r i t i c al i t yAcci dent Consi der ati ons 7

Ot her Concer ns 7

Bur ni ng i s s i l eFuel f ro mDi smant l ed Weapons 7

Di versi on and P r o l i f e r a t i o nPrevent i on 8

Wast e M ni m zat i on 8

Mol t en S al t Ther mal React or Exper i ence 9



A i r c r a f tReact or Experi ment

Ci vi l i an Ori ent edMol t en S al t React or Program

Mol t en S al t React or Exper i ment MSRE 1

Recent Work . 11

MOLTEN CHLORI DE RE TOR 12

Advant ages of a Very Fast Neut r on Spectr um 12

Pr oj ected React or Geomet r y 14

S al tComposi t i ons 14

Thermohydraul i c Consi der ati ons 16

Cool i ngand Heat Exchanger s 17

Conti nuous Pr ocessi ng 17

Pr i nci pal S al t Processi ng Met hods 18

Core S al t Processi ng 2

Abi l i tyt o Di gest Al l Exi st i ngSpent Fuel s 24

MCFR FuelCycl e . . . . . . . . 24

I n cor e Cont i nuous Gas Pur gi ng 25

Del ayed Neut r on Emtters 25

Safet y 26

Anal ysi s of Acci dent Si t uati ons 27

Resi st ance t o Ext er nal Thr eat

3

Effects of Neut r on I r r a d i a t i o nupon Mol t en S al t Chemsty 31

Ef f ect of Chem cal S t a b i l i t yupon Cor r osi on 31

Transmutat i ons of Sodi um and Chl ori ne 32

Chem cal Behavi or of Radi osul phur Obt ai ned by 35Cl n , p 35SDur i ng I n - P i l eI r r a d i a t i o n 32

Fi ssi onProduct Behavi or i n t he Fuel 33



S t r u c t u r a lMateri al s 35

Gener al Consi derat i ons and C r i t e r i a 36

Chem cal React i ons i n an M FR 38

Candi dat e Materi al sf or an M FR 4

Mat eri al sf or t he Core/ Bl anket I n t e r f a c e 4

Chem cal S t a b i l i t yof Hal i des 43

The I r r a d i a t i o nof Mol ybdenum and I r o n i n a Fas t H gh Fl ux React or 44

Enhanced Tr ansmut at i on of 9 Sr and Cs 44

Access and Mai nt enance 45

I n t r i n s i cR e l i a b i l i t y 45

MSR Exper i ence 46

Compar i sonof Pr i mar y Ci rcui t Conf i gur ati ons 46

React or Mai nt enance/ Repl acementPr ocedure 46

React or Shi el di ng

47Radi at i onSour ces i n Pr ocessi ng Equi pment 47

Auxi l i aryPl ant 47

Power Cycl e Opt i ons 8

Auxi l i aryHar dwar e 9

F i l l i n gDr ai ni ngand Dump System 5

Over al l Pl ant Si z e 5

Hi storyof t he MSFR 50

US c t i v i t i es 51

Eur opean Acti vi ty 52

Summary MSR State-of-the-Art 54

REFERENCES 55



Cursory F i r s t Look at t heMol t en Chl or i de Fast React or

as an Al t er nat i ve t o t heConvent i onal BATR Concept

I NTRODUCTI ON

I NEL s present l y st udyi ng t he desi gn and f e a s i b i l i t yof a Br oad w de v ar i e t y )Appl i cat i onf l e x i b l e ,hi gh- f l uxTest i ng React or BATR whi ch woul d event ual l y r epl ace t he Advanced TestReact or ATR at I NEL Thi s paper purposes t o compi l e t he uni que pl uses and m nuses of a BATRbased on t he Mol t en Chl or i de Fast React or MCFR concept I t s ver y fast neut r on spect r umi n anannul ar cor e woul d engender hi gh neut r on f l ux es ,dr i vi ng i nner and out er t hermal neut r on f l u xt r a p s ,each var i abl e i n s i z eand neut r on ener gy spect r um Cont i nuous pr ocess i ng and r ef uel i ng woul dm ni m z e r eact or downt i me Absence of f u e l el ement s and ass oci at ed s t r u c t u r e sshoul d maxi m ze t e s tspace and f a c i l i t a t eaccess t her et o

The paper f i rs t l i s t st he pr oj ect ed BATR r equi r ement s and ms si ons t t hen r evi ews gener i c

c har a ct e r i s t i c sof al l mol t en s a l t r e a c t o r sbef or e f ocuss i ng on t he mol t en chl or i de f a s t r eact or Thel a t t e rconcept was f i r s tpr opos ed as a f u t u r eI NEL hi gh f l u x t e s t i n gr eact or i n 1976 Thi s paper doesnot eval uat e f a s t and t hermal mol t en f l uor i de s a l t r e a c t o r s ,whose neut r on spect r a ar e mch s o f t e r ,asBATR concept s The opt i on of i ncor por at i ng t hose mol t en s a l t v ar i a nt s ,i n whol e or i n p a r t ,doesi n cr e a s et he f l e x i b i l i t yof t he mol t en s a l t TR concept

P ot e n t i a laddi t i onal ms si ons f or an MCFR BATR coul d i ncl ude

Sr and Cs wast e t r ansmut at i on because of ver y hi gh neut r on f l u x

2 Usef ul consumpt i on of f i s s i l efu e l f r o mdi smant l ed weapons because of t he f l e x i b i l i t yi nf u e l f o r m

3 Pr ocess heat appl i cat i ons due t o hi gh t emper at ur e c a p a b i l i t y

4 Li D or Li OD s he l l f or gener at i on of a 14 MeV usi on neut r on t r a p

Thi s paper i s based pr i mar i l yon r ef er ences Ta78, Ot 82 Ga89 and Ga92 t at t empt s t ocursori l y c o l l a t ef o r t yyear s of of f - andon- agai n exper i ence w t h mol t en s a l t r e a c t o r s ,as t appl i es t o aBATR concept , i n t oa r eadabl e summr y Som r edundanci es, i ncompl et eness and i ncohesi veness mybe expect ed i n t h i s sho r t e f f o r t Due t o t h e i rext ensi ve number , t h r e edi f f e r en tnot at i ons ar e used f orr ef er ences i n t hi s f i r stcursory c o l l a t i o n Exampl es ar e [ 1 ] , [ 1 ] ,and [ Ga89] Addi t i onal s p e c i f i cquest i ons may be addr essed by mmbers of t he mol t en s a l t consor t i umand f r i e ndswhi ch i ncl ude Ur iGat ORNL , Taube Sw t zer l and , K Fur ukawa J a p a n ) ,V Novi kov Mos cow , J Moyer andJ

D Lee LLNL , Gol ay M T , Ehud Gr eenspan LBL , Car l Leyse I daho F a l l s )and EO t ew t t e I NEL



TR REQU REMENTS ND MSSI ONS [ Ry91 ]

Requi rements of a TR Concept

The Broad Appl i cat i on TestReact or s t o have a neutron f l u x greater t han 10 n CM 2 s over avol ume of t e n s of l i t e r s broad spect rum of neut ron energi es s needed The core shoul d bemodul ar and f l e x i b l e t shoul d provi de easy access f or mul t i pl e i n- core l oops, beam t ubes, and r a b bi tt ubes i n order t o adapt t o a vari ety of di f f e r e ntmssi ons over t he 30- 50 year l i f e Devel opment r i s kshoul d be reduced The t wo most promsi ng conf i gurat i ons are mul t i pl e- annul ar and mul t i pl ehexagonal

Eval uat i ng t he f e a s i b i l i t yof TR concept s shoul d i ncl ude t he f o l l o w n gconsi derat i ons

Neut r on f l u xl ev el sand energy spectrum

Ther mohydr aul i csFuel s and mat eri al sMechani csR e l i a b i l i t ySaf ety ; a b i l i t yt o respond t o changes i n s a f e t yrequi rementsCost sCompl i ance; a b i l i t yt o respond t o changes i n compl i ance requi rements

M s si ons

Proj ected TR mssi ons, i n approxi mate order of p r i o r i t yi ncl ude t he f o l l o w n g

Fuel s and mat eri al s i r r a d i a t i o nt e s t i n g I sotope product i on Space nucl ear reactor t e s t i n g l a r g evol ume, hi gh power- densi t y space- react or f u el sand

component t es t i ng e g p a r t i c l ebed reactor4 Medi cal research5 Fusi on t e s t i n g6 I nt ense posi t ron f a c i l i t y7 Transmutat i on dopi ng



G N R L MOLTEN SALT REACTORS

Mol t en s a l t r e a c t o r s MSRs empl oy a l i q u i dp e r i t e c t i cmxture of f u e l and c a r r i e rs a l t s

Cool i ngmay be i n- core or e x t e r na l

The opt i mm al t ani on appears t o be t he ha l i des especi al l yf l u o r i n eor chl or i ne Ot her s a l t s a r e a l s opossi bl e [ Ot 82] Hal i des aff ord on- l i ne processi ng, i nhe r e n ts a f e t y desi gn si mpl i ci ty and ef f i ci ency Mol t en s a l t t echnol ogy s wel l devel oped and experi ence hasbeen good s ee page 9

Mol t en s a l t r e a c t o r scan operate at therml , epi therml or f a s t neutr on energi es They can serveas power r e a c t o r sf i s s i onpr oduct burners, and f u e l converters or breeders The power r ange s a l s oextr emel y f l e x i b l ewi th no s a f e t ycompr omses They ar e s u i t a b l ef or smal l and standby powerappl i cati ons i n r emote, unat t ended or f or- def ense a pp l i c at i ons Operat i onal mdes r ange f r o mconti nuous processed f uel t oa l i f eti me- seal ed reactor They have t he p ot e nt i a land pr oms e t o becomet he t h i r dgener at i on r e a c t o r s The l ea dt echnol ogy r e s i d esi n t he U S [ Ga89]

Physi co- Chem cal Features

The choi ce of f i s s i l emteri al i n MSR fue l s a l t does not s er i ous l ya f f e c tt he s a l t pr oper t i es

Hence, a gi ven reactor pl ant woul dbe capabl e of usi ng f i s s i l emteri al s i n a r bi t r ar ycombi nat i ons f orhi gh- t emperat ure, hi gh- ef f i ci encypower oper at i on

S a l t sa r e chemcal l y s t a b l eand evi dence good compati bi l i t y wi th mter ia l s Mol t en s a l t sw l l not chemcal l y i n t e r a c twi th a i r or water, r egardl ess of t emperat ures However , anyi nt roduct i on of hot obj ect s i n t owater coul d l ead t o a steam expl osi on Som MSR

cocnept s empl oy an i nt ermedi at e s a l t t o pr ecl ude t he p o s s i b i l i t yof radi oacti ve s a l t

i n t e r a c t i n gwi th wat er

2 They ar e nonf l ammabl e, aver t i ng f i r ehazards

3 Fuel and cool ant do not r e a c t wi th ai r and wat er when bot h ar e at t he same t emperat ure

4 No possi bl e evol ut i on of gaseous hydr ogen f r o mfue l or pr i mar y cool ant

5 Fuel and pr i mar y cool ant f eature hi gh boi l i ng poi nts and l ow vapor pressures

6 I n st agnant cool ed fo rm t he fue l does not rel ease t he vol a t i l e f i s s i onproducts

7 Som s a l t sare sol ubl e i n water, f a c i l i t a t i n gcl eanup of any l e ak s

P e r i t e c t i cmel t i ng poi nt

P e r i t e c t i cbehavi or i mpl i es t h a t t he mxi ng of two s a l t s l ower s t he mel t i ng poi nt f a r bel ow t h a tf or e i t h ers a l t by i t s e l f The amount of l ower i ng depends on t he mol ar r a t i oof t he two s a l t s except i onal l y l owt emperat ure s possi bl e at t he eut e ct i c poi ntor n ad i r Thi s may be of speci al val uef or non- f uel s a l t s wher e l t t l heat i s gener at ed

fue l mx wi th mel t i ng poi nt wel l bel ow 7 °C woul d m ni m z e a u x i l i a r yheati ng when shutdown and al l owa l arge t emperat ure r i s e i n the core wi thout reachi ng hi gh o ut l ett emperat ures >1000 C Low mel t i ng poi nts of t he component s a l t sa l s o wi l l f a c i l i t a t et h e i ri n i t i a ldi ssol uti on



Fl ui d Fuel Features

Fl ui d- f uel r e a c t o r sd i f f e rs i g n i f i c a n t l yf romal l t he present s o l i d - f u e lr e a c t o r s they cont i nuousl y

add fu e l and r emove f i s s i o nproduct s and requi re no f u el r ef a br i c at i on I ndeed t he e n t i r es o l i d - f u e l -el ement f abri cat i on process avoi ded Thi s saves a s i g ni f i c ant par tof t he head- end e f f o r tand cost

I t a l s oadds f l e x i b i l i t y

Fuel prepared f or an S can be conveni ent l y shi pped as a col d s o l i dand remel t ed j u s tbef ore i t added t o t he reactor system For smal l a dd i t i o nst he react or can be desi gnedt o accept the f uel i nt he f rozen s ta te as i n t he Mol t en S al t React or Exper i ment MSRE

The fu e l can be bl ended i n t o t he react or on an ad hoc ba si s at t he s i t e The amountadded wi l ldepend on i t s i s o t o p i cmakeup and concentr at i on but al l can beaccommodat ed by t he react or These advant ages ar e par t i c ul ar l yi mport ant f or f u e lderi ved f romweapons

3 There i s no need f or l ong l e ad t i mes and i n t e r i mst orage or f or exact l ong- range pl anni ngtha t may be upset by v ar i a t i o nson e i t he rt he suppl y or t he demand s i d e

Fl ui d fu e l can be t r a n s f e r r e dremot el y by pumpi ng t hrough pi pes connect i ng st orage andreact or

Mol t ensal t r e a c t o r s MSR have been mor e ext ensi vel y devel oped t han ot her f l u i d - f u e lpower system

Thermohydraul i c Aspect s

Low vapor pressures up t o hi gh t emperat ures and f avorabl e heat t r a n s f e rp r o pe r t i e sr e s u l ti nhi gh t her mal ef f i c i e nc i e s f o rMSRs Thi s precl udes s a f e t yhazards associat ed w t h hi gh pressures suchas rupt ures or depressuri zat i ons

Specific t hermohydr aul i c advant ages i nclude the fo l l o wn g

Al l component s f u e l pr i mary cool ant i n t he cont ai nment exhibi t l ow vapor pressure

Exi st ence of a l ar g e heatsink

3 Under any of f - nor mal condi t i ons t he l i q u i df u e l can be channel ed t o a cont i nuousl ycool ed drai n t ank i n a sho r t t i me

4 Nat ural convecti on r emoves decay heat

5 Can use a l ow mel t i ngpoi nt d i l u t i n gs a l t contai ni ng neut ron poi son as a core cat cher

The p e r i t e c t i cnat ur e of t he hal i de s a l t s f a c i l i t a t e sl ow t emperat ur e operat i on i n t he near term bym n im z in g chemcal l y- reduci ngcorr osi on probl em w t h Mo-Fe a l l o ys Wt h g r a ph i t e t h e s eprobl emmay not e xi s t L a te r hi gh t emperature operat i on l eadi ng t o hi gher eff iciencyprocess heat atcomposi t i ons away f rom t he e ut e c t i cnadi r can be i mpl ement ed when mor e i s known about ma te r i a lcorr osi on Of f - eutecti ccomposi t i ons can a l s omean hi gher BG and t her mal conduct i vi t y of s a l t



Hal i de s a l t sa l s o of f ersuper i or t hermal and r adi ati on s t a b i l i t y Thi s i n h i b i t st he f ormat i onofot her compounds , t her eby pr event i ng corr osi on

The ORNL MSR pr ogr amshows t ha t fue l s a l t c i r c u l a t i o ni s f e a s i b l e: i t i s f a c i l i t a t e di n pa r t byl oweri ng of mel t i ng poi nt s i n p e r i t e c t i cmul t i - component mxtures Chem cal s t a b i l i t yand cor r os i on oft he mol t en s a l t sar e f a i r l ypredi ct abl e

Heat t r a n s f e rdepends on fue l s a l t densi t y p t hermal conduct i vi t y k ) , v i s c o s i t y p) , ands p e c i f i cheat C ) O t h e s e , p T) p T), and Tm. p. ) ar e wel l known f or si ngl e s a l t s; much l es s sof or s a l t mxtures Knowedge of k T) f or mxtures i s b e t t e r , but s t i l lski mpy Maj or u nc er t a i n t i esi npredi ct i ng hf f or a m x tu r e shoul d s tem f r o mal l par ameter s except p T)

Ext er nal ool i ng

Havi ng t he f u e l i n a f l u i ds t a t e al l ows e x t e r na lcool i ng, t her eby avoi di ng s t r u c t u r a lcomponent si n f i el dsof s i g n i f i c a n tr adi ati on damage I t al so el i mnates l abor and mater i al costs associ at ed w t hf u e l el ement decl addi ng, d i s s o l u t i o n ,and f abr i cati on Fuel handl i ng by pumps and pi pi ng shoul d bel e s s compl ex than s o l i dfue l handl i ng The si mpl i f i edcore shoul dgreat l y ease t he pl ant desi gn, andi ncrease i t s r e l i a b i l i t yand a v a i l a b i l i t y ,t her eby decr easi ng cost

l u i ds t a t e systemal so f a c i l i t a t e so n - s i t ecl ose- coupl ed fue l processi ng Ext er nal cool i ngoft he mol t en s a l t al l ows t he pr i mary c i r cui t t ooperate at l owpressure: t h i sr educes t he s ev er i t yof t heenvi r onment and al l ows mat er i al s such as gr aphi t e f or pi pi ng

El i m nat i on of f u e l cl addi ng and s t r u c t u r a lmater i al s i g n i f i c a n t l yi mpr oves t he neutron econom

of t he reactor more neut r ons ar e avai l abl ef or

br eedi ng, r educedc r i t i c a l

mass , or ot her t r a d e o f f s

The pri nci pal di sadvant age of ext ernal cool i ng w i l lbe t he hazar d associ at ed w t h mul ti pl ec r i t i c a lmas ses pr esent i n t he pl ant out s i de t he reactor

ont i nuous On Li ne Processi ng

Fi ss i onproduct FP) i nvent ori es i n MSRs can be s i g n i f i c a n t l yr educed [ Ta78] by

Cont i nuous pur gi ng ofv o l a t i l e Ps w t h hel i umwhi ch r emoves

a nobl e gases w t hi n a per i od of m nut es ) ,

b hal ogens and t r i t i um,p a r t i a l l y ,and t o some ext ent t he nobl e and sem nobl e met al si n t he f o r mof aer osol s w t hi n a per i od of hours);

On- si t e chem cal hi gh-t emper atur e processi ng r emoval of t he non- vol at i l e ps and, i fneeded, some hazar dous a c t i n i d e s w t hi n a per i od vary i ngf r o mhour s t o weeks )

The f e a s i b i l i t yof t he var i ous s t e p sf or on- l i ne processi ng has been cal cul ated and i ndi vi dual l ydemonst r at ed at ORNL [ 16 , 17 ] I n addi t i on, t heur ani umrecovery s t e pwas demonst r at ed i n t he

MSRE when t he f i s s i l emater i al was changed f r o mur ani um 235 t o ur ani um 233 The process

i nvol ved 47 hour s of f l u o r i n espar gi ng over a si x-day per i od [ 5 1 t o pr oduce a urani umpr oduct pure



enough f or cascade r e- enr i chment

The f i s s i o npr oduct i nvent ory i n an e a r l i e rconcept of t he Mol t en S al t Breeder React or MSBR , was pl anned t o be a 10- day accumul ati on [ 7 ] mor e r ecent proposal

[ 1 8 ]suggest sr educi ng t he f i s s i o nproduct s t o a l e ve l wher e t he e n t i r ea f t e r h e a tcan be cont ai ned i n t he s a l t w t houtr eachi ng boi l i ng The l i m t t o t he r educt i on of f i s s i o npr oduct i nvent or y i n t he r eact or w i l ldepend onfactors of econom cs and f i s s i o npr oduct concent r at i ons among ot hers

Cont i nuous processi ng o n - s i t em ni m zes t he f i s s i l ei nvent ory envi r onment al hazar d andp r o l i f e r a t i o ndanger out si de t he reactor t he i nvent or y i n t he c o r e pi pi ng and heat exchanger sr epresent s al most t he ent i r e f uelcycl e i nvent or y Fuel s not t i e dup i n other pl a nt sor t h e i r t empor ar yst or age depot s t s a l s onot under t r a n s p o r tt o or f ro msuch l o ca t i o nsel i m nat i ng hi ghj acki ngsabotage and t r a n s p o r t a t i o nacci dent s F i n a l l y t never even occur s i n a form or cont ai ner s u i t a b l ef ort r a n s p o r t

Cont i nuous processi ng a l s or emoves hazar dous and neut r on- absorbi ng f i s s i o nproduct s whi l eaddi ng fresh shi m f u e l f rom t he opt i onal br eedi ng bl anket or f ro m sur pl us weapons Pu Thi s g r e a t l yr educes t h e pot e nt i a lr adi ol ogi cal danger of t he r eactor whi l e i ncreasi ng t he neut r on economyProcessi ng onl i ne al so al l ows on- l i ne r e f u e l l i n g That r educes downt i me and obvi ates mechani cal shi mdevi ces i ncreasi ng t he neut r on economy

React or Saf et y

MSRs possess many i nherent safety p r o p e r t i e s

Al r eady bei ng a mol t en f u e l f u r t h e r mel t down cannot occur

Fl ui d fu e l has i nher ent l y a strong negat i ve t emper at ur e c o e f f i c i e n tof r e a c t i v i t ydue t oexpansi on gr e at l y i nhi b i t i ngboi l i ng

3 El i m nat i onof pressur i zed and pressur e- evol vi ng component s i n s i d et he cont ai nment

El i m nat i onof t he p o s s i b i l i t yof gas and vapor evol ut i on especi al l y t he r el ease of f r e ehydr ogen and at t endant f i r ehazard

5 Reduced r i s kof r a d i o a c t i v i t yr el ease out si de t he cont ai nment due t o

a r educed r i s kof f a i l u r eof t he cont ai nment and

b two orders of magni tude r educt i on i n t he FP decay heat sour ce r e l a t i v et oconvent i onal s o l i d - f u e lr e a c t o r s due t o cont i nuous o n - s i t echem cal processi ng

6 Reduced FP i nvent or y i mpr oves t he c a p a b i l i t yf or emer gency heat r emoval by natur alconvect i on t her eby g r e a t l yr educi ng t he desi gnat ed evacuat i on a r e a

7 F l u i d i t yf a c i l i t a t e sr emoval f rom t he reactor t o ever - saf e cont ai ner s

8 Hi gh heat capaci t y of f u e l r e s t r i c t st emper at ur e r i s e on l o s s of nor mal cool i ng



Low s a l t vapor pressure mni mzes t he e f f e c tof any t emper ature r i s e

Leakage of Radi oact i ve Sal t

I n MSRs f ue l c i r c u l a t i n gt hroughout t he reactor syst em Consequent l y t he probabi l i t y of as i g ni f i c a nt r a di oa ct i vi t yl eak of l i q u i d - f u e lshoul d be hi gher c ompar ed t o s ol i d- f uelr e a c t o r sand t heconsequences mor e severe However t he ba r r i e r st o ext ernal FP rel ease f r o man MSR ncl ude t he

React or cool ant boundary,

Seal ed react or vessel pr i mary cont ai nment

3 React or bui l di ng secondary cont ai nment

I n a ddi t i on, pr a ct i ca l l ya l l MSR concept s remove f i s s i o ngases and v o l a t i l e scont i nuousl y, reduci ngs i g n i f i c a n t l yt he po t e nt i a lradi oact i ve source t e r m i n t he system Thi s reduces bot h t he r i s kofdi s p er s a lof r a d i o a c t i v i t yand t he amount of decay heat t h a t must be cont ended wi t h duri ng anacc i dent Fl u i df u e l a l s oal l ows shut down of t he reactor by drai ni ng the core i n t os u b c r i t i c a lcont ai ners f rom whi ch any decay heat can be readi l y r emoved by conduct i on and natural convect i on

Cr i t i c al i t y cci dent Consi derat i ons

For f i s s i o nr e a c t o r sone must prot ect agai nst c r i t i c a l i t yacci dent s duri ng fue l handl i ng I n MSRst he f u e l c r i t i c a li n t he mol t en s t a t ei n some opt i mal conf i gurat i on Thi s precl udes mos t s ol i d- f uel

c r i t i c a l i t yacci dent scenar i os wher e t he f u e l mel t s or sl umps I f t he fue l escapes t

opti mumenvi r onment or conf i gurat i on e g f a i l u r eof t he pri mary cool ant boundar y , i t wi l lbecomes u b c r i t i c a l. I n t h er ma l MSRsa gr a p hi t emoder a t or i sr equi r ed f or c r i t i ca l i t y. Thus c r i t i ca l i t yc a n

occur onl y i n t he core For ot her concept s, t he desi gn must si mpl y excl ude vessel s t h a t are notc r i t i c a l i t y - s a f ef or credi bl e fue l mxtures I n a ddi t i on,t he a b i l i t yt o add f u e l wi t h t he reactor on- l i nest rongl y l i m t st he amount of excess nucl ear r e a c t i v i t yt h a t must be avai l abl e

The mol t en nat ure great l y be ne f i t ssafety a s wel l: i ncrease i n t emperature causes a strongdecrease i n f ueldensi t y The i nherent s t a b i l i t yof t h i s negat i ve t emperature c oef f i c i entwi l l l i m texcursi ons el f - r e gul a t i ngsystem may be pos s i bl e,avoi di ng t he need f or cont rol el ement s

O her Concerns

Burni ng F i s s i l eFuel f rom D smant l ed Wapons

MSRs are s u i t a b l ef or t he be ne f i c i a lu t i l i z a t i o nof f i s s i l emater i al f romdi smant l ed weapons f ore f f i c i e n tand economc al energy pr oduct i on MSRs can u t i l i z eal l three maj or f i s s i l ef u el s:urani um233, - 235, and pl utoni um as demonst r at ed i n t he MSR Thi s f l e x i b i l i t yi s achi eved wi t houtreact or- core desi gn modi f i cati ons

Fuel recycl i ng and f abri cati on a r enot necessary F i s s i l e scan be t r e a t e dcompl et el y a t t hehead- end di smant l i ng f a c i l i t y Fuel shi pment s i z e sa r e a r b i t r a r yand t hus opt i mal l y s a f eand fue l

t r a n s p o r t a t i o n reduced t o a mni mum [ Ga92] The bul k of t he wast e can be : educed i n vol ume and



br ought i n t oshape s i z e f or m chem c al combi nat i on nd shi pment and di sposal s i z et ha t ar e t he mos taccept abl e or what ever e l s e may be deemed desi rabl e f or s a f e t y s e c u r i t yec onomy or pr ac t i c al i t y

The denatur i ng nd spi ki ngcan render t he fu e l u n a t t r a c t i v ef or p r o l i f e r a t i o nor di versi on Al l these

f a c t o r scombi ne t o possi bl y reduce p ot e n t i a lpubl i c obj ecti on

he fu e l suppl y f romt he di smant l ed nucl ear devi ces coul d be augment ed at any t i me or t o t a l l ydi spl acedby f u e l f r o mother sources y adj ust i ng other component s of t he f u e l t he convers i on r a t i ocan be contr ol l ed w t h i n r a t h e rw de l i m t s Thi s f u r t h e rassures uni nterr upted cont i nued operati on ofmol t en s a l t r e a c t o r sf or support of t he ov er a l lenergy economy The f ac t t hatno s u b s t a n t i a ldesi gnchanges ar e requi red t o ccommod te f i s s i l esuppl y changes a c t s as dampe r on t he propagati onofi n t e r r u p t i o n schanges i n schedul e or pl ans Thi s f l e x i b i l i t ya l s omoder at es any c o s t st h a t m ght r e s ul tf r o mchanges and i n t e r r u p t i o n s

D ver s i on and Pr ol i f er a t i on Pr event i on

he r e l a t i v e l ysi mpl e r emote handl i ng al l ows even t he f r e s hf uel t obe hi ghl y r adi oact i ve whi chprovi des a strong di versi on i n h i b i t o r Al so hi ghl y r adi oact i ve f u e l can be detected e a s i l y I f t het emperat ure of t he fu e l s al l owed t o drop t he f u e l s o l i d i f i e s nd agai n s d i f f i c u l tt o mani pul at epr ovi di ngaddi t i onal di versi on pr ot ect i on

SRs can be desi gned i n an ext r emel y s a f emanner w t h i nherentl y s a f epropert i es t ha t cannotbe al tered or t amper ed w t h These s a f e t ya t t r i b u t e smake t he SRs very a t t r a c t i v eand maycont r i but e t o t h e i reconomy by r educi ng t he need f or el aborat e s a f e t ymeas ur es

SRs further requi re a mni mum of s p e c i a lf u e l preparati on and can t o l e r a t edenatur i ng andd i l u t i o nof t he f u e l Fuel shi pment s can be a r b i t r a r i l ysmal l whi ch may reduce t he r i s kof di vers i on

Waste M n i m z a t i o n

Al l f i s s i o nr e a c t o r sgenerate radi oact i ve wast e SRs w t h t h e i rcont i nuous on l i ne r emoval oft he wast e f r o mt he r e s i du a lfu e l greatl y si mpl i f y t s subsequent handl i ng On l i ne processi ng cans i g n i f i c a n t l yreduce t he t r a n s p o r t a t i o nof radi oact i ve shi pment s t h e r e s no shi ppi ng bet ween t hereactor and t he processi ng f a c i l i t y Storage r equi r ement s ar e a l s oreduced as t h e r ei s no i n t e r imstorage f o r e i t h ercool down or preparat i on f or shi pment he wast e havi ng been separated f r o mt hef u e l requi res no accommodat i on f or e i t h e rc r i t i c a l i t yor f u e l di versi on concerns t he wast e shi pment scan be opt i m zed f or wast e concerns al one

The a c t i n i d e scan be r ecycl ed i n t o t he f u e l f or bur ni ng and l argel y el i mnated f r o m t he wast e

El i mnat i ngt he a c t i n i d e sf r o mshi pment s and f r o mt he wast e r educes t he very l ong contr ol l ed storaget i me of t he wast e t o mor e accept abl e nd r easonabl e per i ods of t i me [19 ] The on s i te on l i neprocessi ng a l s oal l ows f or t he i n s e r t i o nof some s e l e c t e df i s s i o nproducts l i k e l ong l i vedi odi ne backi n t o t he reactor f or t r ansmutat i on

The f i s s i o nproducts al r eady bei ng i n processi ng f a c i l i t yand i n a f l u i dmat r i x can beprocessed t o t he opt i mal f o r mdesi red That s they can be r educed i n vol ume by concent rat i on ord i l u t i o nt o t he mos t desi rabl e c ons t i t u t i on hey can be further t r ansf ormed i n t o t he mos t d e s i r a b l echem cal s t a t e shape s i z e or conf i gurat i ont o meet shi ppi ng and/ or s torager equi r ements Thecont i nuous processi ng al soal l ows maki ng t he shi pments t o t he f i n a l d i s p os a ls i t e as l a r g eor as smal las desi red Thi s can reduce t he r i s kassoci ated w t h each i ndi vi dual shi pment t o an accept abl e l e ve l



One pri mary f a c e t of t he nucl ear wast e pr obl emi s tha t reactor operat i on i nduces short - andi nt ermedi at e-l i ved r a di oac t i v i t yi n mat eri al s whi ch had been s t a b l eor onl y l ong- l i ved radi oact i ve Thesol uti on i s t o al t er n at i vel y s t o r et he acti vat ed mat eri al s unt i lt hey decay, or t o t r ansmut e thembacki n t oharmess s t a b l eor quasi - st abl e nucl i des When operat i on produces nucl i des whi ch poi son t heenvi r onment and l a s t l ong, t hen ecol ogypref ers t he added speed of t r ansmutat i on

Fuel cycl e wast es occur i n pr epar at i on of t he f u e l m l l t a i l i n g s )react or operat i on spent fue land acti vat i on of ai r and water ) and react or decomm ssi oni ng a ct i v at i onpr oduct s of s t r u c t u r a lmat eri al s) The l a t t e r are general l y n on vo l a t i l e ,boundup i n t he s t r u c t u r a lma t e r i a l ,and ext r emel ydi f f i cul t t orel ease t o t he envi r onment , even i n acci dent s i t u at i ons The m l l t a i l i n g sare i nherent l yl ow- l evel ol dup t anks and st acks w t h l a r ge di l u t i o nf a c t o r smanage t he ai r and wat er a ct i v at i o ns

Management of t he spent fu e l poses t he maj or pr obl em al l others pal e i n compar i son

I n t he absence of US r epr ocessi ng spent fue l has accumul at ed recent l y such as t o s a t u r a t et heu t i l i t ystorage pool s To prevent l o s sof nucl ear generat i on, DOE pl ans t o f i n daway- f rom r eact or

storage capaci t y f or 810 MT of spent fu e l by 1984 and at l e a s t25, 000 MT by 1996 Forei gnspentf uel wi l ladd t o these r equi r ements [3 2 ]

Mol t en Sal t Thermal React or Experi ence

The U S Depar t ment of Energy and i t s predecessor agenci es carri ed out t wo very successf ulreactor exper i ment s t he Ai r c r a f tReact or Exper i ment ARE) [ 4 ] and t he Mol t enS al tReact orExper i ment MSRE) [ 5 1

Ai rcraf t Reactor Experi ment

I n 1947 ORNL began a st udy on t he physi cs chemstry, and engi neeri ng of urani um andt hori umbeari ng mol t en f l uori des MSR t echnol ogy f i r s tappeared i n t he open l i t e r a t u r ei n 1957 Bri ant and Wei nberg[ l ] ) The p ot e n t i a lf or ver y hi gh t emper at ures and power densi t y i n t er e s t e dt heai r c r af tpropul si on proj ect

The RE [ 1 , 2 , 3 , 4 , 6 ]was a product of t he Ai r c r a f tNucl ear Propul si onProgram was aberyl l i ummoderat ed, t hermal react or f uel ed w t h a UF4/ NaF/ Zr F mx and cont ai ned i n I nconel Thereactor successful l y operat ed i n 1954 f or mor e then 90, 000 kWhr w t hout i n ci den t ,at t her mal power sup t o 5 nd t emper atures as hi gh as 1650°F

That programwas subsequent l y di scont i nued, but a c i v i l i an- o r i ent e dMol t enSa l t React orProgram MSRP that began i n 1956 [ 5 ] cont i nued devel opment of t h i s general t echnol ogy

Civi lI an- Orl ent ed Mol t en Sal t Reactor Program

The pri mary goal of t he e a r l yMSRP and f or most of t he t her mal mol t en s a l t r e a c to rprogramwas t he devel opment of a t her mal Mol t enS al t Breeder React or MSBR f or economc c i v i l i a npower[ 5 , 7 ]usi ng t he Th- 233Ufue l cycl e The MS R was concei vedas a near t her mal react or w t h agraphi t e moder at or The pref erred s a l t sare f l u or i des ,i nc ludi ng beryl l i umand l i t h i u mf l u or i des ,f ort h ei rdesi red nucl ear and t her modynam c p r o pe r t i e s Bot h t he beryl l i umand t he f l u o r i n ecausesi gni f i cant neutron moderat i on To achi eve breedi ng w t h t he s o f t neutr on spectrum i t i s necessary t os e l e ct t he t hori umcycl e [ 1 5 ]



I n order t o compet e w th other concept s usi ng t he 238U- Pufu e l c y cl e t he e f f o r twas f ocused ona system wi th i n t e g r a lo n - l i n echemcal pr ocessi ng I t i ncl uded

1 Eval uat i ng t he most promsi ng desi gns

Pi npoi nti ngs p e c i f i cdevel opment pr obl em

Devel opi ng materi al s f or f u e l s contai ner s and moderat or s

4 Devel opi ng component s, especi al l y pumps , val ves, and f l anges s u i t a b l ef or ext ended usewi th mol t en s a l t sat 1300°C

5 Devel opi ng suppl ement ary chemcal processes f or r ecover i ng val uabl e component s otherthan ur ani um f r omspent fu e l

6 Devel opi ngand demonst r ati ng t he mai ntai nabi l i ty of an MSR system

I n 1963, Al exander [ 6] summar i zed t he Oak Ri dge devel opment

The s i mpl i c i t yof t he reactor core and t he sem- conti nuous fu e l handl i ngapparatus l e adt o l ow c a pi t a lc o s t sand i ncr eased p l a nta v a i l a b i l i t y

The s i mpl i c i t yand conti nuous nature of f i s s i l eand f e r t i l estream pr ocessi ng met hods l e adt o negl i gi bl e fu e l cycl e c o s t si n o n - s i t epl a nt s

3 The negat i ve t emperat ure c o e f f i c i e n tof r e a c t i v i t yi nherent i n t he t her mal expansi on of

t he f u e lpr ovi des safety advantages over other reactor concept s

4 The i nternal l y- cool ed reactor o f f e r scompeti t i ve nucl ear per f or mance t he e xt e r n al l y -cool ed r e a c t o r superi or per f or mance

The MS R e f f o r twas di sconti nued i n 1972, r esumed as a t echnol ogy- devel opment program i n1974, and f i n a l l ycl osed out i n 1976 e s i d ua lpr obl emwas that Hast el l oy- Nl im te d t het emper atur es of t he ORNL MS R t he addi ti on of carbi des i n t othe grai n boundar i es keeps He f r o mfo rmng and swel l i ng t h e r e but at hi gh t emper at ur es t he carbi des di sappear i n t othe gr ai ns EZebr oski of EPRI f e l t tha t t he pr obl emw t h t he MS R was whet her t he system p a r t swoul d hol dtogether very l ong [ 10 ]

Mol ten Sal t Reactor Experi mnt MSRE)

The MSRP e f f o r tl ed t o t he desi gn, constr ucti on, and operati on of the 8-MWh Mol t en S al tReact or Exper i ment MSRE) C r i t i c a loperati on of t he MSRE spanned the peri od f r o mJ une 1965 t oDecemer 1969 Duri ng that t i me the reactor accumul at ed over 13,000 equi val ent f ul l - power hours ofoper ati on and demonst r at ed r emarkabl y hi gh l ev el sof o p e r a b i l i t ya v a i l a b i l i t yand mai ntai nabi l i ty

The MSRE was operated i n i t i a l l yw t h 23 5Uas t he f i s s i l efu e l at about 35 enr i chment Thatoper ati on spanned 34 mont hs begi nni ngi n 1965 and i ncl uded a sustai ned r un of 188 days p a r t l yatl owpower t o accommodat e t he exper i ment al program Al l aspects of operat i on, i ncl udi ng theaddi ti on of f i s s i l efu e l w t h t he reactor operati ng at power , wer e demonst r ated Subsequent l y t hemxture of 5U and 238Uwas r emoved f r o mt he s a l t s by f l u o r i n a t i o no n - s i t eand 233U was added t o t he



f u e l s a l t f or t he next phase of the opera t i on Pl ut oni umpr oduced dur i ng t he 235 U operati onr emai ned i n t he s a l t dur i ng t he 233U operati on. Several f i s s i l eaddi t i ons consi sti ng of PuF, wer e made[ 1 5 ]f or fue l makeup t o demonst r at e t h a t capabi l i t y. The pl ut oni umaddi t i ons wer e made by addi ngcapsul es of t he PuF3 i n t hes o l i df o r mt o t he reactor s a l t and a l lowng t he pl ut oni ums a l t t o di ssol ve.Thus, pl ut oni umf r o mt wo sour ces was bur ned i n t he MSRE t he added pl ut oni umand t he pl ut oni umt h a t was bred f r o mt he ur ani um 238 i n t he i n i t i a loperat i ons.

Thus, t he same r e a c t o r ,w t hout changes i n desi gn, oper ated successf ul l y on al l of t he maj orf i s s i l ef u e l s ur ani um 235 and - 233, and pl ut oni ummxed w t h ur ani um Thi s property pr ovi des t heul t i mat e f l exi b i l i t y i nt he u t i l i z a t i o nof f i s s i l efue l.

Recent Wor k

I n recent y e a r s ,B a t t e l l eNor t hwest Labor at ory BNW) has made c r i t i c a lexper i ment s onMSBR conf i gur at i ons [ 7]. Sever al Uni t ed St a t es uni ver s i t i eshave st udi ed t he chemstry of mol t en

s a l t s [ 8]. NL i d ent i f i ed t heneed [ 9] f o r i n - p i l ecorr osi ont e s t i n gat hi gh bur n- ups t o c l a r i f yt he e f f e c tof nobl e- met al deposi t i onon cont ai ner met al .

Germany st udi ed a var i ant cal l ed t he Mol t en S a l t Epi t her mal MOSEL) reactor [ 11 , 1 2 ] Toenhance breedi ng i n t he t hor i umc y c l e ,t h i s concept f orgoes t he gr aphi t e i n t he c o r e , t h a t i s used as amoder at or i n other MSR concept s . That har dens t he spectr um r eachi ng i n t ot he peak r egi on of t heur ani um 233 neut r on y i e l di n t he epi t her mal spect r um [ 11 ]

smal l MSBR desi gn st udy was under t aken i n 1978 as p a r t of DOE s Non- prol i f er at i ngAl ternati veSys t ems Amassment Pr ogr am( NASAP) [ 8 ]. Thi s st udy exam ned addi t i onal MSR

concept s t h a t mght o f f e rgreat er resi stance t o nucl ear p r o l i f e r a t i o nt han t he l i ght - wat er r e a c t o r soperati ng on a once-t hrough fue l cycl e he st udy l ed, ul t i mat el y, t o t wo s imlar concept ual MSRs

one, a break-even br eeder [ 8 , 9 ]usi ng a compl ex, on-l i ne f ue l pr ocessi ng pl ant and t he other asi mpl i f i edconvert er [ 1 0 ] , w t h a once- t hrough 30- year f ue l cycl e.

By mxi ng t he fue l w t h adequat e propor t i ons off e r t i l ema t e r i a l ,conver si on t o ei t h erpl ut oni umor ur ani um 233 i s possi bl e Cal cul at i ons have i ndi cat ed pr omsi ng conver s i onr a t i o s(near 9) f o r avari ety of condi t i ons and val ues above . 0 may be achi evabl e under c a r e f u l l ycont rol l edcondi t i onsw t h on-l i ne pr ocessi ng t o r emove f i ssi onpr oduct poi sons. W t h an appr opr i at e fue l c y c l e ,one f i s s i l emater i al can be bur ned of f al most compl et el y or bur ned and convert ed i n t oanot her. As an exampl e,one coul d bum pl ut oni umand pr oduce ur ani um 233. Such a conver si onw i l l t ransforma f u e l ,pl ut oni um par t i cul a r l y s ui t a bl ef or weapons, i n t oa f u e l , ur ani um 233, t h a t may be l e s s s u i t a b l ef orweapons but mor e neut r on pr oduct i ve i n non- f ast spectra . Fur t her mor e, whi l e pl ut oni umcoul d be

separat ed f r o mt he s a l t o r other a ddi t i v es )by chemcal means, ur ani umw i l lcont ai n s u bs t a nt i a lamount s of ur ani um 232 whi ch i s consi der ed a strong d e t e r r e n tt o p r o l i f e r a t i o n. he very strongr a d i o a c t i v i t yemanat i ng f r o mt he ur ani um 232 decay product s makes any d i r e cthandl i ng prohi bi t i veonl y a s h o r tt i me a f t e rchemcal p u r i f i c a t i o n.

More r ecent l y some concept s i n J apan [13] and at ORNL [14] addr essed si mpl i ci ty of desi gnand enhanced s a f e t yas t he pr i mary goal s .



MOLTEN CHLORI DE RE CTOR

The l i g h t e s tneutr on- moderat i ng materi al of si gni fi cance i n t he MCFR dri ver f u e l i s chl ori ne

at om c wei ght 35 5) The consequent very f a s t neutron spectrumengender s l ow f i s s i o nandcapture cross s e c t i o ns That i nduces a hi gh neut ron f l u xper f i s s i o nor un i t power and good neutronec onomy, provi di ngneut r on l eakage i s wel l t r e a t e d For a B TR concept , one m ght conf i gure t hedri ver f uel i nannul ar geomet r y s i m l a r t o current B TR desi gns I n t e r i o rt o t he annul us, moderat i ngmater i al such as t he Sr OD and CsOD used i n Taube s FP bur ner concept , woul d gi ve a hi gh t her malneutron f l u x t r a p That woul d pr ovi de abundant t her mal neut r ons f or t hes t a t e dB TR m ssi ons

Corr espondi ngl y, w tht h i sconcept one m ght consi der addi ng Cs and Sr t r ansmut ati on t o t he s t ofB TR m ssi ons

The excel l ent neutron economy al l ows one t o choose bet ween br eedi ng f u e l ,bur ni ng up f i s s i o nproducts , i sotopepr oducti on, i r r a d i a t i o nt e s t i n g ,and f undament al research i ncl udi ngw t h neutronbeams ) These a l t e r n a t i v e st h u s become t he ba s i sf or contr ol l i ngand usi ng t he neut r on l eakage

The mol t en s t a t eof t he f u e l enabl es even hi gher neutron fl uxes by perm tt i ng r e a c t o roperati onat very hi gh power de ns i t i e s Some MCFR desi gns f or power oper ati on approach 10 GWm thesewoul d not l i k e l ybe needed here Al so, t he very s t ee p f i s s i o nr a t e gradi ent acc ompanyi ng a t her malf l ux t r apmakes a mol t en f u e l core e s s en t i a lsi nce t he l o ca lf i s s i o ndensi t y can be one order ofmagni t ude greater than t he mean densi t y I n a s o l i d - f u e lcore such hi ghheat r emoval r a t e s woul d notbe achi evabl e

I n al l cases a d i r e c t l ycoupl edcont i nuousl y oper ati ng processi ng pl ant s proposed Some of t het echnol ogi cal pr obl ems of processi ng are di scussed I mpuri ti es accumul at i ng i n t he mol t en s a l t mayi nduce corr osi onon i r r a d i a t e ds t r u c t u r a lmat er i al s

dvantages of a Ver y Fast Neut r on Spect rum

n MCFR e x h i b i t sa very f a s t neutron energy spect r um chl ori ne atomc wei ght A=36cons t i t u t e s t h el i g h t e s tmaj or el ement t he s a l t contai ns onl y smal l amount s of Na A=23) or K A=39)

Thus no strong el as t i c s cat t e r er spervade t o moder at e t he neut ron s ener gy Choosi nga hi gh mol arcontent of UCI 3i n t he cor e s a l t f u r t h e ri n h i b i t st he neutron moderat i on The p r i n c i p a lmoderat i ngmechani sm then de f a ul t st o heavy el ement i n e l a s t i cs c a t t e r

Tabl e compar es t he medi an f l u xener gy of t he r e s u l t i n gneutron spectrumt o t ha tf or other f a s tr e a c t o r s Si nce t he neutron capture cross secti on decreases w t h energy and many i sotopes exhi bi tthreshol d behavi or f or f i s s i o n Fi gur e 1 t he hard spectrum enhances f i s s i o nover capture The r e s u l ti s t h a t

Reacti vi ty per u ni t mass i n cr e a s e s ,decr easi ng t he c r i t i c a ls i z e

Mre a c t i n i d e snow i s s i o nu s e f u l l yr a t h e rthan j u s t t r ansmute i n t oahi gher- Aa ct i ni de

3 The 233U n , 2 n cross secti on f or pr oduci ng 232U, a pr ol i f e r at i on det e r r ent ,i n cr e a s e s

4 P a r a s i t i cneutron capture by f i s s i o nproducts and s t r u c t u r a lmat eri al s decr eases, therebyi mpr ovi ngt he neutron ec onomy, and decr easi ng t he s e n s i t i v i t yof t hos e mat er i al s



Tabl e Fast React or Compari son

Fuel Medi an F l uxCycl e Reactor Energy

238U / Pu N L 1000 MWe LMFBR 130 keV

AI 1000 M e LMFBR 180 keVFast a ZPPRs 190 kev

GCFR Latt i ce 187 keV1000 MWe GCFR Desi gn 176 keV

MCFR i n cor e cool i ng 198 keVM F R i nter nal bl anket,

out- of - core coop 370 keV

U tr a-H gh Fast Fl ux 471 keV

Nol ten Ch ori de TestReactor

ThU M FR out-o f c ore coophi gh enri ched 700 kev



5 Both 233Paand 234Utend mor e t o f i s s i o n Thi s el i mnates t he need t o remove and hol d233Pa f or decay i nto 233 U

I na

pl ut oni umf uel edMCFR t he hi gh a ct i ni de dens i t y,t he

absence of core i ntemal s, and t hevery f a s t neutron spectrum can combi ne t o r a i s eBG up t o 7 233U/ Thsystem coul d probabl y onl yachi eve G of 2 t o 5. Shoul d one pref er a BG near z e r o , t he l o ca lneutron economy can be di vert edt o other advantages such as smal l er bl ankets, sl ower f i s s i o nproduct cl eanup, added Th i n t he core mxt o reduce power d en s i t y,cool i ng i n - c o r e ,or operati on at l ower p e r i t e c t i coperat i ng t emperat ures

The f a s t neutron spectrum a l s oi mpl i es l owf i s s i o nc r os s s ec t i o nsr el a t i ve t oa t hermal neutronspectrum To accompl i sh t he same power densi t y as i na t hermal system t he f l u xl e v e l smust exceed10 6n cm 2 sec The l a c kof core i ntemal s l i m t sradi ati on damage probl em i n t he external cool edMCFR On t he pl us s i d e, such f l u x l e v e l smght b en ef i tMCFR v a r i a n t ssuch as hi gh f l u x[7 5 ]reactors f or mol ecul ar s t ud i e sand radi o- medi ci ne product i on [76] and f l u x - t r a pbumer r e a c t o r sf ort roubl esome f i s s i o nproduct t ransmut ati on [2 3 ]

Pr oj ect ed React or Geomet ry

The best MCFR ar r angement mght be a smal l number of c y l i n d r i c a lt ubes i n a skewed annul arconf i gurati on The chai n reacti on woul d concentrate wher e the tubes converge However , as no fue ls a l t boundari es e xi s tal ong the tube axes , c r i t i c a l i t yboundari es bl u r

Skew ng the tubes woul d keep t he hi gh l e v e l sof neutron f l u xand power generat i on i n t hepri mar y s a l t away f ro mt he reactor vessel wa l l s , dependi ng on i ndi vi dual tube s u b c r i t i c a l i t y,di stanceof separati on bet ween tubes , and angl e of t h e i rskew For exampl e, i f they a r e near c r i t i c a lby

t hemel ves and ar e di s t a n tf rom one another, then t h e i r f l uxes wi l l f ol l owa cosi ne d i s t r i b u t i o nover t het o t a l di stance bet ween bends However , i ncreasi ng t he i n t e r - t u b ecoupl i ng cause t he f l uxes w t hi n t het ubes t o f a l l of f mor e steepl y beyond the tube convergence regi on

Not e t h a t i f one keeps the tubes f a i r l ydecoupl ed, t h a t approaches t he ATR type of operati onwher e power l e ve lcan be vari ed by l obe Her e one coul d a l s o vary t he neutron spectrumby tube orl obe by runni ng separate c i r c u i t si n one or mor e t ubes and choosi ng a di f f e r en ts a l t composi t i on

Th concent rat i on and o the rf ue l s a l t paramet ers wi l l a l s oa f f e c tneutron d i s t r i b u t i o n sbecausethey moder at e t he neutrons whi ch shortens t h e i rmean f r e e path Fl uxes wi l la l s oextend i n t o t hebl anket i n al l di r e c t i o nsbut wi t h much shorter rel axati on l engths

The choi ce of tube ar r angement w i l ldepend upon a det a i l ed t r a destudy of e f f e c t i v ecore s i z e:ext ensi on of t he chai n r e a c t i o nout al ong t he t ubes wi l l i ncrease exposure of t he pressure vessel t oneutrons emanat i ng f rom t he tubes mak i ng t he core s i z esmal l reduces s t a b i l i t yof t he system t operturbati ons

Sal t Composi t i ons

The l i m t i n gc r i t e r i ai n t he search f or f u e l , f e r t i l emteri al and cool ant s f or i n t e r n a l l ycool ed systemar e as f ol l ows

smal l e l a s t i cscat t er i n g f o rf a s t neut rons



2 smal l i n e l a s t i cs c a t t e r i n g

3 l ow neutron capture cross- secti ons f or f a s t neutr ons

4 t her modynam c and k i n e t i cs t a b i l i t yof pl ut oni umand ur ani umcompounds

5 mel t i ng poi nt bel ow7 °C i n t he pure s t a t eor i n t he di ssol ved s t a t e

6 boi l i ngpoi nt above 1500- 1600 °C f or bot h pure and di ssol ved s t a t e s so as t o m ni m z evapor pressure

7 s t a b i l i t yagai nst at mospher i c c o ns t i t u e nt s ,oxygen, wat er car bon di oxi de

8 hi gh t her mal conducti vi t y and s p e c i f i cheat capaci ty

9 l owf u e l s a l t vi scosi ty so as t o m n i m z e pumpi ng c o s t s

10 good corr osi onpr oper t i es i f possi bl e

11 adequat e technol ogi cal or l abor atory exper i ence

12 r e l a t i v e l ycheap and avai l abl e materi al s

13 non- t oxi c

Gr aphi cal s t u di e sof mos t of these paramet er s may be f ound i n [ Ot 82]

These w de r angi ng c r i t e r i aar e f u l f i l l e dbes t by t he chl ori ne compounds PuCl3, UCl 3 and NaCl ,due especi al l y t o chl ori ne l ow neutron moder at or NaCI i s t he per i tec t i c- f orm ngc a r r i e rs a l t ofpref erence due t o i t s abundant occur r ence i n nature [ Ot 82] Fl uori de s a l t scan a l s obe r un as a f a s treactor but not w t h Li and Be as i nt he t her mal MS R concept

The be s t neutron economy of an M FR i s achi eved w th PuCl3 or 233UCl 3 as f i s s i l efu e l E taval ues of 5U ar e s i g n i f i c a n t l yl ower at hi gh neut ron energi es The corr espondi ng f e r t i l ef u e l saregeneral l y 238UCl 4or ThCl , Br eedi ng of r epl acement f u e l obvi ates t he need f o r i s ot opi cenr i chmentprocesses

Tabl e 2 summar i zes t he i nt er compar i sonof c a r r i e rs a l t cat i ons The goal of keepi ng t he core

spectrumhard di scour ages use of Be and Li t h e r ebecause of e l a s t i cdownscat t er ; Ca andK

downscat t er t he l eas t Na under goes t he mos t i nel as t i c s cat t e r; Ca and K t he l e as t P a r a s i t i cneutroncapture t hough smal l exceeds by magni t udes f orLi and K over tha t f or Ca, Mg and Na Cat r ansmutes t he l e as t i n t or a d i o a c t i v i t yor t r oubl esome chem cal s

Cati onchoi ce on t he b as i sof p e r i t e c t i cmel t i ng poi nt depends on t he range of accept abl eacti ni de mol ar contents Boi l i ngpoi nts f or c a r r i e rchl ori des pl ay no r ol e ast hey f ar exceed those f ora c t i n i d echl or i des The chem cal s t a b i l i t yt he a l k a l ichl or i des NaCl and KCI surpasses tha t of t heal kal i ne ear t hchl or i des MgCl , andCaCl , NaCI abounds by f a r t hemos t i n nature and c o s t st hel e as t S al t densi t y a f f e c t spumpi ng power needs but t he hi gher de ns i t i e sof t he a c t i n i d echl or i desdwarf any di f f erences due t o c a r r i e rs a l t choi ce The l i g h ta l k a l i st r a n s f e rheat the bes t



I n summar y NaCI costs l i t t l eand e x h i b i t sgood physi cal and chemcal propert i es and Caf eat ure b e t t e rnucl ear propert i es f or t he core s a l t but t he much hi gher Cl concent rat i on obscures t hemNa and L i l ook best f or t hebl anket s a l t Fi nal choi ce must wei gh t hese r e l a t i v eadvant ages pl us t hel ocati on of p e r i t e c t i cmel t i ng poi nts near t he desi red a c t i n i d emol ar f r a c t i o n

Thermohydraul i c Consi derati ons

The mol t en s t a t eal l ows hi gh power d ens i t i es up t o 10 er l i t e rand hi gh t emperatureoperat i on whi l e at l ow pressure Fuel mel t i ng s p a r t of t he desi gn and so s not a probl em Fuelvapori zat i on does not occur unt i lext r eme t emperatures contri but i ng t o l ow operat i ng pressures Onl yt he cont ai ner mat eri al s i mpose t emperature l i m t s W t h Mo a l l o y s900°C appears t o be an upper l i m t Graphi t e s t r u c t u r e sshoul d t o l e r a t econsi derabl y hi gher t emperat ures H gh t emperat ure operat i oncoul d a l s ol ead t o process heat mssi ons

The c r u c i a lpar amet er here i s t he core power densi t y The gi ven val ue i s h i g hbut s t near t he

present s t a t eof t he ar t power de ns i t i e sf or some hi gh f l ux r ea c t or s Tabl e 3

Tabl e I nt ercompar i son of Sa l t Cat i ons

Rat i ng Accor di ngt o Core Sa l t Goal s

good i nt ermedi at e poor

nucl ear p r o pe r t i e se l a s t i cs c a t t e r K Ca Na Mg Pb Li , Bei n el a st i c s ca t t er K Ca e Li , g Na Pbneut ron absorpti on Mg Ca Li , Na Pb e Li , r a d i o a c t i v i t y Ca Pb Mg Li , Cs Li , Be Na

Rb Sr , Bai mpuri t y mutant s Ca Sr , Cs K Na Be a Mg Li , Pboveral l nucl ear Ca K Mg Na Pb Li , Be

physi cal propert i es P K Na Li , Pb Mg Ca eb p vapor p r e s s al l o k

heat t r a n s f e rcoef Li , g Na K Ca Pb Rb Cs Ba Sr

chemcal behavi ors a l t s t a b i l i t y Na K Rb Cs Mg Ca Pb Sr , Ba

economcsc os t Na Ca K Mg Li , Pb e

di sposal same as r a d i o a c t i v i t y

overal l compari soncore Na K Ca Mg Pb Sr , a Li , Be

Mg Ca K Pb Li , Bebl anket Na 7L i



Cool i ng and Heat Exchangers

The f u e l s a l t may be cool ed external l yor i n- core Under t he ext r eme operat i ngcondi t i ons ofver y hi gh neut r onf l uxes and hi gh s p e c i f i cpower , e x t e r na lcool i ng s preferred Thi s l eads t o hi ghf u e l i nvent or y and mul t i pl e c r i t i c a lmas ses i n t he pri mar y l oop

Conti nuous Processi ng [17, 81, 141- 146]

Mol t en s a l t r ea ct o r s of f ert he advant ages of o n - s i t econt i nuous pr ocessi ngusi ng chemcalseparati on pr ocesses i ndi genous t o t he hi gh t emperat ure mol t en s a l t medi a Fi s si onproduct s may begr ouped i n t ot h r e ecl asses

FPA f i s s i o nproducts of a l k a l iand a l k a l ie a r t hbut a l s or a r e e a r t hel ement s whi ch have f r e eent hal py of chl ori de f ormati ong r e a t e rt han t hose of PuCl

FPS f i s s i o nproducts of sem- nobl e met al s w t h f r e eent hal py of f ormati onsmal l er than thoseof PuCl

FPE f i s s i o nproducts e x i s t i n gi n el ement ar y f o r mbecause of t he l ow f r e e ener gy of chl ori def ormati onor negati ve bal ance of chl ori ne

The pyrochemcal separat i on of pl ut oni umor ur ani umf r o m t he i r r a d i a t e dfue l coul d be car r i ed out i nt he f ol l ow ngs t e p sof t he met al transport process

Mol t en s a l t pr i mary phase Pu, FP p a r t of FP r emai ns

Metal l i cphase p a r t of FP r emai ns

Mol t en s a l t secondar y phase cont ai ni ngonl y Pu

Tabl e 3 Power densi t y i n hi gh- f l uxr e a c t o r s

Power densi t y GWth / m

i n core vol ume i cool ant vol ume

Fei nberg , researchreactor 3- 5 8- 10

Mel ekes CM2 Sovi et Uni on 2- 5 5

FFTF USA 1- 0 2

Lane Mol t en chl ori des 5- 10 5- 10

HFI R USA meanmaxi mum

2

4- 384

8- 5

Pheni x 250 France . 46 1

Thi s paper 10- 9 10- 8



Some processi ng shoul d occur cont i nuousl y, some bat chw se Bat chw se w i l l general l ybee as i e r mor e e f f i c i e n ti n separ at i on, and mor e econom cal Thi s study does not deal w t h t hen ea r - i d en t i c alconcerns associ at ed w t h s t a r t i n gear l yc o r e sup w t h PuCl or 235UCl3 i nst ead of

U l

Cor e s al t pr ocessi ngr emoves f i s s i o nproducts, oxi des, corr osi onproducts, and chl ori net r ansmutat i on products; pa r t cont i nuousl yand part bat chw se I t al s o r e adj us t st he chl ori nest oi chi ometr y

Pri nci pal Sal t Processi ng Methods

The S concept i nherent l y avoi ds mny of t he convent i onal processi ng s t a ge s ,especi al l y fu e lel ement di ssol ut i onand refabri cat i on. The absence of these stages r emoves t he need f or hi ghdecont am nat i on st ages i n pr ocessi ng P r o l i f e r a t i o nconcerns al so di scour age hi gh decont amnat i on

r e s i d ua lr a d i o a c t i v i t ymakes weapon constr ucti on hazardous El i mnat i ngal l t h e s estages r educes c o s t s

Thi s l eaves j u s t t he separ at i on stages core s a l t cl eanup and bred-Uextr acti on f r o mt he bl anket

The most pr om si ngmet hods ar e by

Sol vent extr acti on f r o maqueous sol uti on

Vo l a t i l i t y

Pyr ometal l urgy

Pyrochemst r y mol t ens a l t el ec t r o l y s i s

We f i r s t r evi ew t he chemstry of t he heavy el ement s

Chemstry of t he Heavy El ement s[ 81] The separ at i on processes, es pec i al l ythose basedon sol vent ext r a ct i on, t a keadvant age of t he somewhat unusual chemcal behavi or of t he ac t i n i des

El ement s i n t he anal ogous l anthani de s er i esal l e xhi bi ts im la r chemstry t he presence of th ree ,r e l a t i v e l yl oosel y- bound, out er e l e ct r o n scauses each at om t o exhi bi t a p o s i t i v eval ence of 3

The ac t i n i des al s oal l f o r ma t r i p o s i t i v e I I I val ence s t a t e However , some a l s oevi dencel oosel y-boundi nner el ectr ons Thi s l eads t o t e t r a p o s i t i v e I V ,pent aposi t i ve V , and hexaposi t i ve V1 s t a t e s

These hi gher oxi dat i ons t a t e sevi dence di f f e r e nts t a b i l i t i e s Tabl e 4 whi chf a c i l i t a t e se x t r a c t i o nand separ at i on of t he heavy el ement s Th and U d i f f e rpronouncedl y, Th evi denci ng most l y j u s t t heI V s t a t e

The I I Iand I V s t a t e se a s i l ypr e ci pi t a t ef r o maqueous s ol ut i onas f l u o r i d e s; t he V or VI s t a t e s donot The f l uor i desof t he I I I and I V s t a t e sdo not v o l a t i l i z e; t he V I - s t a t ef l uor i de sdo at f a i r l yl owt emperat ures The I V and VI s t a t e sappr eci abl y di s s ol v ei n cert ai n organi c l i q u i d; t he I I I - s t a t eni t r at e sr emai n v i r t u a l l yi n s o l u b l ei n t h e s el i q u i d s



Sol vent Extracti on f r om queous Sol uti on The extr act i onof a ct i ni de sf rom aqueouss ol ut i onby an organi c sol vent i s t he most advanced process: i t has been w del y used si nce about1951 The Thor ex vers i one x t r a c t s 3U f r o maqueous s o l u t i o nof i r r a d i a t e dTh f ue l el ement s [ 7 ] I tr e l i e son t he s t a b i l i t ydi f f er encesbet ween Th and U n hi gher val ence s t a t e s Tabl e 4

The f a c i l i t yof sol vent ext ract i onf or mul t i - stage opera t i onw t hout consumng addi t i onal heat orchemcal s p a r t i c u l a r l yb e n e f i t s

Si t uat i ons requi ri ngext r eme p u r i f i c a t i o n Use of enough st ages can l ower t he gamma c t i v i t yf r o mf i s s i o nproduct s i n t he extractedur ani umt o be l owthat of natural ur ani umThus one mght not want t o f urni sh t h i s c a p a b i l i t yt o a f o r ei gn nat i on

2 Si tuat i onswher e t he pr opert i es of t wo m t a l s p a r a l l e lone anot her so cl osely that a s i n g l ep r e c i p i t a t i o nor c r y s t a l l i z a t i o ncan not se pa r a t et o t he degr ee r equi r ed Thus t h i s met hodmy not be needed f or Th U separati on

The di ssol ut i onst ep f o r a c hl or i de s a l t has t o be t he si mpl est of al l: j us t add wat er Di f f erentorgani c s o l v en t sseparat el y e x t r a c tt he U, Th, and wast es Addi t i onof Cl and CCl 4subsequent l yrechl ori di zesU and Th

Di sadvant ages associ ated w t h t h i s met hod i ncl ude

Extra c r i t i c a l i t yprecaut i ons f orH- moder at ed fue l sol ut i ons

2 Mul t i pl i c i t yand compl exi t y of s t e ps

3 Large wast e vo l umes

4 Large shi el ded space r equi r ed

5 Addi t i onal s t e ps needed t o pr oduce s o l i dwast es

Tabl e 4 Rel at i ve s t a b i l i t i e sof oxi dat i ons t a t e s of t he a ct i ni deel ement s [ 8 ]

Atomc NoEl ement

89 c

9Th

91Pa

92U

93Np

94Pu

95 m

96 m

97Bk

I I I

I V

VI

Legend most s t a b l es t a t edecreasi ngl y s t a bl e



Vo l a t i l i t yProcesses Vol at i l eUF b. p. 56 . 4 ° C e a s i l yseparates f r o mf i s s i o npr oduct and Thf l u o r i d e s. The a b i l i t yt o decont amnat e t o l ow a c t i v i t yl e vel s par al l el st ha t f or sol vent extract i on.However , t he v o l a t i l i t ymet hod r e q ui r e sf ewer s t e p sand therefore smal l er vol umes of hi ghl y-

radi oact i vewast es compar ed w t h aqueous processi ng.

Vo l a t i l i z a t i o nshoul d work especi al l ywel l f orprocessi ng a ThF4/ NaF or other f l u o r i d ec a r r i e rbl anket s a l t mx One woul d oxi di zet he bred UF4 t o UF separate i t by d i s t i l l a t i o n ,chl or i di zei t andr educe i t t o UCl3 The r emai ni ng ThF4woul d return t o t he bl anket.

Di s t i l l i ngUCl UCl5, or UCl6 f r o ma mx of ThCl 4 andchl or i desof t he s t r u c t u r a lmater i al s andf i s s i o npr oduct s woul d be mor e d i f f i c u l t: mor e v o l a t i l echl or i des compounds e x i s tand t h e i rvapor- pressure ranges over l ap However , consi derabl e l o s s devel opment e f f o r thas been expended onmet hods f or separati ng v o l a t i l echl ori des; t he probl em may be sol vabl e.

Pyr omet a l l ur gi ca lProcessi ng I n t he 1950 s NL devel opedpyr ometal l ur gi cal processest o recover and puri fy f i s s i l eand f e r t i l emter i al f r o mbreeder r e a c t o r s. Al t houghdemonst r at ed on ap i l o t - p l a n ts c a l e ,much engi neeri ng devel opment r emai ned t o evol vea wor kabl e and r e l i a b l eprocess,especi al l y i n vi ewof c r i t i c a l i t yr e s t r i c t i o n s.

t y p i c a lprocess woul d use a mol t en chl ori def l ux t o cont act t he oxi de f ue l and a mol t en met alt o e x t r a c tt he a c t i n i d e. Hence t he need f or hi gh t emper at ure pyro). W t h mol t en chl ori de s a l t f u e l sonl y t he e x t r a c t a n t needed: f or chl ori def u e l s ,Di l l on[28] pr oposeda Mg Zn a l l o y. s imla r met almay work w t h Th/ U cycl e chl or i des.

Pyrometal l urgi cal processesdecont amnat e by f a c t o r sof onl y about one hundr ed W t h t hemone mus t handl e fue l whi ch poses no probl emf or mol t en s a l t processi ng: t r e q ui r e sno fue l

fabri cat i onor ot her handl i ng;

everyt hi ng

done r emot el y anyhow Leavi ngi n r a d i o a c t i v i t ya l s oi n h i b i t suse of t he mat er i al f or weapons.

Because of i t s compact ness , pyromtal l urgi cal process can operate cl ose- coupl edt o t he r e a c t o rand on a much s h o r t e rcycl e t han t heaqueous route. I f economcal , a pyrochemcal processi ng p l a ntcoul d e a s i l ybe ac commodat ed w t hi n t he reactor bui l di ngdue t o i t s smal l s i z e. Pre l i mnary worki ndi cat es t h a t c ap i t a land operat i ng c o s t smay be hi gh because of t he smal l batch type operat i onsneeded .

Detract i ons i ncl udel ow recovery r a t e sand t he devel opment needed t o cope w t h t emper at ur esabove 1000°C. H gh t emper at ure equi pment of grea t r e l i a b i l i t yt ha t can be operated and r epl acedr emot el y i s hard t o desi gn and expensi vet o t e s t. However , work al r eady done i ndi c a t e st h a t t hed i f f i c u l t i e smay be ove r come.

Mol t en Sal t El ect r ol ys i s. Techni ques e x i s t t o deposi t a c t i n i d eoxi des and car bi des f r o mmol t en s a l t s ol ut i onthrough e l e c t r o l y t i cr educti on [143] e. g. UO2+2 sol n) 2e = U s o l i d at t hecat hode . At t he anode: 2 Cl - s o l n = C1 gas 2e . Si m l a r l yTaube [ 147] ment i oned r educi nga c t i ni de sd i r e c t l yi n t h e i rmol t en chl ori de mxtu re. The C1 r el eased coul d be used t o chl ori di ze ThO2f or bl anket feed.

Core Sal t Processi ng

On equi l i br i umc y cl e ,t he core f uel wi l li ncl ude c a r r i e ra l k a l is a l t e. g. NaCI ) , f i s s i l eUCl 3,di l uent ThCl 4, a c t i n i d et r ansmut ant s e . g. PaCl 4, NpCl3 and PuCl3 , i mpur i t y oxi des, f i s s i o n

pr oduct s i n



var i ous f or ms and s t a t e s s t r u c t u r a lcor r os i onpr oduct s, and sul fur f ro mchl or i ne t r ansmutat i on Someof t he mut ant s may f o r mcompl ex chl ori des l i k e Cs2UCl 6and compounds l i k eUI and US whi chp r e c i p i t a t eout at sundry t emperat ur es

Core s hi mmater i al mus t repl ace i r r a d i a t e dcore s a l t near cont i nuousl yso as t omai ntai nc r i t i c a l i t y The f u e l bumup r a t e 1. 6 gmmn f or a 2250 MWh pl a nt f i x e st he r a t e of s hi mr epl acement Act ual core s a l t pr ocessi ng can s t occur batchw se or cont i nuousl y The choi ce wi l ldepend i n p a r t on t he al l owabl e i nventoryof core s a l t i n r epr ocessi ngand t he al l owabl e l e ve lof FPconcent r ati ons i n t he cor e The l a t t e rdepends on

l The r e a c t i v i t ywor t h of FP

2 The e f f e c tof l ower Th U r a t i oor i nc r easedreactor s i z eon reactor per f or mance

3 The e f f e c tof FP on G

4 Accept abl e r a d i o a c t i v i t yl e v e l si n t he pri mar y c i r c u i t hi gh l e v e l snecessi t ate r emot epr ocessi ng and extr a pl ant shi el di ng

Recovery Opti ons The f i r s t opt i on s whet her t o cl ean up t he s a l t r emove t he bad p a r t orj u s t recover t he 233UCl 3and scrap t he r e s t si nce NaCl s so cheap Sol i dfu e l cycl es convent i onal l ytake t he l a t t e rappr oach Her e we choose t o cl ean up t he s a l t because

NaCl r a d i o a c t i v i t ypr ecl udes easy di sposal

2 Enr i chment i n 3 7Cl i fchosen woul d f o r f e i tcheap c os t ar gument s

3 Di scar di ngnon-ur ani uma ct i ni de swoul d mean poor f uel ut i l i z at i o nsi nce every a c t i n i d ea tomcan event ual l y f i s s i o n i n t hi sspectrum

4 Cont i nuousgas r emoval gi ves a good s t a r t on s a i l cl eanup

I t mght be f e a s i b l et o j us tremove t he p a r a s i t i cneutron absorbers and cor rosi on agents: l et t hes a l t accumul at e t he r e s t of the most l y- r adi oac t i venon-vol at i l emut ant s, some as s ubs t i t u t ec a r r i e rs a l t

The advant ages ar e

l u i t a b l epl ace t o s t or e non- v ol a t i l eradi oacti ve wast es

2 The reactor wi l l t r ansmut e many of t he wast es i n t oa l e s s hazar dous f o r m

3 The r a d i o a c t i v i t ywi l l add t o t he heat source

4 The r a d i o a c t i v i t ydi scour ages di vers i onof t he cor e s a l t f o r weapons pur poses

Pot ent i al di sadvantages t o wat ch f or and control a r e

Change i n v i s c o s i t yand other t hermophysi cal propert i es

2 Mut ant pl a t e - o utcausi ng f l o wbl ockage, radi ati on s o u r c e s ,or ot her pr obl em



The enumer at ed advant ages seem r e a l enough t o warrant t h i sbasi c appr oach p r a c t i c a l i t i e smayrequi re som modi f i cat i ons

Conti nuous Remval of Mut ant Gases Fi ssi onproduces Se, Xe, Kr, I 2, and Br 2whi chare al l gases at reactor t emperatures Thr eshol d r eac t i o ns al s oproduce He and HT gas One ton off u e l f romt he core of a f a s t br eeder cont ai ns x 10° Ci of 85Kr ,100 Ci of 131Xe a f t e rcool i ng 4months) , 130 and 7 Ci of I a f t e rcool i ng 4 and 6 mont hs, r e s pe ct i v el y , 13 Ci of 129I and 2200Ci of T I n an MSR c i r c u i tr u p t u r e ,t h e s ewoul d al l present a radi ati on hazar d Gas accumul ati on wi l lal so bui l d up pr es s ur e , af f e ct i ng c i r c ul at i o n

I n r emedy f or t he MSBR ORNL proposed a cl eanup system whi ch r e c i r c u l a t e sgas i n l oopsacross each mai n s a l t pump I nj ected hel i um nucl eat es bubbl es whi ch absorb gas es , t h es mal l - p ar t i c l ef og of i ne r tmetal s ( Pd, Tc, Ru, Rh, and Te) and som of t he v o l a t i l echl ori des Whi l e i n a hol d- up t ankt o r educe decay h e a t , some of t hemetal s and chl ori des deposi t out Passage t hrough t r a p sand bedsr emoves Kr, Xe, water, e t c bef ore returni ng t o t he hel i um i n j e c t o r About 20 of t he bypass f l owunder goes a l ong del ay i n whi ch al l i sotopes except t he 10- year 85Krdecay t o an i n s i g n i f i c a n tl e ve l

Present l y 85Kr l e vel sf ro mr e a c t o r sare smal l enough t o di schar ge d i r e c t l yt o t he at mospher e Shoul d nucl ear power abound i n 30- 40 years i t may be necessary t o separate out Kr; l ow- t emper aturef racti onati on l ooks l i k ea promsi ng met hod

Evapor ati on and f r a c t i o n a t i o ncan a l s oconcentrate t r i t i u mf o r l engthy storage t h i s i s present l ydone i n s o l i dfue l r epr ocessi ng

An i nt er medi at e h a l f - l i f emakes 137Cs one of t hemor e t r oubl esome f i s s i o nproducts ; onl y asmal l port i on of t he A=137 y i e l dcomes d i r e c t l yt o 137Cs Though t he gaseous precursors decay

r e l a t i v e l yqui ck, cont i nuous gas extr acti on coul d r emove al o t

of them bef or e non- gaseous Csf ormed Thi s woul d

Lower t he a c t i v i t yof t he c i r c u i t

2 Avoi d t he mor e d i f f i c u l tr emoval of CsCl or other comound l a t e r

3 Hel p i s o l a t eCs f or i ndi vi dual i zed vol ume r educt i on

The mai n desi gn parameter s f o r gaseous f i s s i o nproduct r emoval are

1 The absorpti on requi red i n t he del ay beds

2 The hea t r emoval needed t o avoi d excessi ve t emper at ur e r i s e i nt he charcoal t r a p s

One fo rmof del ay bed i s a trough of sw mmng pool s i z e Low pressure st eamf orms above t he pooland passes t o condenser uni t s Such a system woul d dwar f t he r e a c t o ri n s i z e Al t e r na t i v el y,onem ght s t o r et he gases s a f e l yand r e l i a b l yat hi gh pressure

Remval of Non- Gaseous F i s si on Product s The i ne r tmet al s not escapi ng as f og wi l ll i k e l ydeposi t i n var i ous p a r t sof t he pri mary or FP r emoval c i r c u i t s External pr ocessi ng wi l lr emovet he r emai ni ng 50- 60 f t he f i s s i o nproduct s as necessary unl ess on- l i ne t reat ment pr ocesses can bedevel oped



We ment i oned t h r e epossi bl e processi ng met hods above O t hese sol vent extr acti on f romaqueouss ol ut i oni s t he best est abl i shed However , economcs may requi re t he processi ng pl ant t o

serve mul ti pl e reactor f a c i l i t i e s Processi ng at a di f f er ent l oc at i on,woul d mean

I ncr eased out- of - pl ant i nvent or y

2 I ncr eased hazar d of r a d i o a c t i v i t y ,sabot age, and p r o l i f e r a t i o n

Combi ned w t h t he di sadvant ages ment i oned above, t h i s argues f or consi derati on of t he l ess- devel opeds a l t processi ng met hods

Control of t he Oxygen Level s Oxygen and oxygencont ai ni ng compounds r e a c t w t h l

t o p r e c i p i t a t eur ani umoxi des and oxychl or i des Oxygen can ent er t he s a l t t hr ough a i r wat er vapor ort r ansmutati on of F The vagar i ous nature of a i r and wat er vapor entry n ec e s s i t a t e skeepi ng t he oxygencontent wel l bel ows a t u r a t i o n A cont i nuous gas bubbl i ng system w t h chem cal r educi ng agent

shoul d hel p ; so shoul d t he appr eci abl e capac i t y of the s a l t f or oxygen

Exper i ment i n d i c a t e sd i f f i c u l t yw t h si mpl e met hods of s a l t cl eanup such as t he smal l change i ns o l u b i l i t yby t emperatur e adj ust ment An a l t e r n a t i v ee f f e c t i v emet hod routes t he bypass gas f l owt hr ough a bed, wher e t he gas mxes cont i nuousl y w t h i n j e c t e dl i q u i dNaAl Cl4 Gr eat er s t a b i l i t yof

Al 2O3causesi t t o f o r m o ver Al Cl 3. The s ol i d a l um nathen s epa r a t es outby f i l t r a t i o nor c y c l o ne.

Removal of Sul f ur I mpuri t i es Sever al nucl ear r eact i ons conver t chl or i ne t o s ul f ur Massbal ance and Coul omb b a r r i e r scombi ne t o i n h i b i tmos t of t h e se r e a c t i o ns ,but hi gh f l u x l e v e l sbol st erproducti on 35Cl converts t o 32S

S and S CI shoul d pr oduce onl y smal l amount s of °S f avor i nga 17 Cl enr i chment agai n A na tu r a lchl or i ne- f uel l ed system w i l lpr oduce mor e s ul f urt han t he s a l ts o l u b i l i t ycan handl e Phosphorus , t hough pr esent i s onl y t r a n s i t o r y,decayi ng qui ckl y t o s u l f u r

The pr esence of s u l f u r ,or of any otherel ement capabl e of compoundi ng w t h urani um need notadver sel y a f f e c t t hef e a s i b i l i t yof t he system si mpl e adj ust ment of t emperatur e and UCl 4 content cani nduce p r e c i p i t a t i o ni n a cl eanup c i r c u i t Because one can r e l i a b l epredi ct t he producti on r a t e of thesemut ant s, t he concentr ati on i n t he core coul d be s a f e l ymai ntai ned cl ose t o s a t u r a t i o n t hen even ani n e f f i c i e n tr emoval process woul d s u f f i c e

The e f f e c tof t he s u l f u rpr esence wi l l ,i n p a r t , depend on i t soxi dat i on s t a t e For mol t en s u l f u r ,t he o x i d a t i o n - s t a t eequi l i br i umi s f a i r l ywel l f i xed; t he pr edomnant s t a t e t ends t o be pos i t i v e The p o s i t i v i t yal so i ncr eases w t h i r r a d i a t i o n

Mai ntai ni ng the Chl ori ne Stoi chi omet ry Each a c t i n i d eatom n i t i a l l ybi nds t h r e eor fourat oms Al t hough f i s s i o ns p l i t seach a c t i n i d eatom i n t otwo pr oduct atom, t he net val ency r educes i np a r t due t o i n e r t gases and an excess of chl or i ne occurs Thi s can l ead t o several cor r osi on agent s,e s p e c i a l l yUCI The i nt ense f i s s i o nf r agment i r r a d i a t i o nof t he s a l t pr oduces short - l i ved i o ns whi chqui ckl yoxi di ze UCI , t o UCl 4

To hol d down t he concent r at i on of UCl 4,and excess Cl i n general ; one can r e a c t t he f uel sal t ata modes t r a t e w t h met al of natur al urani umor thor i um or w t h other r educi ng agents

Stori ng Troubl esome Fi ssi on Product s by Usi ng Them as Car r i er Sal t O al l t hef i s s i o nproducts, 90Sr and 7Cs shoul d present the mos t tr oubl e However Sr and Cs bel ong t o t hea l k a l i n ee a r t hand a l k a l ic l a s s esof el ements A good way t o manage these l ong- l i ved s a l t sm ght





reactor f u e l cyc l e

Have l ow neut r oncross sec t i ont o avoi d neut r oni cs penal t y

2 e non- volat i l eso as t o not pose a hazard i n a transport acci dent

3 e d i f f i c u l tt o separate f r o mt he c or e s a l t

Tr oubl eso me l ong- l i vedf i s s i o npr oduct s mght be i d ea l

I n Core ont i nuous Gas Purgi ng

I n- core cont i nuous gas pur gi ng of t he mol t en f ue l can s i g n i f i c a n t l yi mpr ove t he s af e t yof ani n- core acci dent

mxture of hydr ogen- hel i umgas s cont i nuousl ybubbl ed t hr ough t he l i qui df u e l i n t he core

The mean dwel l t i me of t he gas bubbl es needs t o be contr ol l edand t he mean transport t i me of t hemol t en component s t o t hese bubbl es mus t a l s obe cont ro l l ed: e. g i f speed- up i s d es i r e d ,i nt ensi vem x i ng; i f del ay, l o c a laddi t i onof a f u r t h e rgas s t r eam

The ai m of t he gas s t r i p p i n g s as f o l l ows

1 t o r emove t he v o l a t i l ef i s s i o nproduct s whi ch i n t he c ase of an ac ci dent c ont r olt heenvi r onment al hazar d: I - 1 31 ,Xe- 133, Kr - 85and precursors of Cs- 137 For t het her mal r e a c t o r ,one woul da l s or emove t he I - 135, precursor of Xe- 135, t o i mpr ove t heneut r on bal ance

2 t ocontrol t he pr oduct i onof del ayed neut r ons si nce most of t he precursors and nucl i desof t h i s gr oup ar e very v o l a t i l e ,e g Br- l - i sotopes

3 r emoval of oxygen and sul phur , cont i nuousl y

4 i n s i t ucontrol of cor rosi onpr obl ems on s t r u c t u r a lmater i al s

For a f i r s tapproxi mat i on, a r b i t r a r i l yas sume a gas f l u x of 30 cm3/ s nor mal s t a t e of H2/ He. At 20 barpressure and w t h a dwel l i ng t i mei n core of 20 seconds, t he gas bubbl es wi l lonl y occupy a f r a c t i o nof t he core equal t o 10 of t s vol ume and have l t t l i nf l uenc e of t hec r i t i c a l i t y , but t he col l apsi ngof

bubbl es r e s u l t si n a p o s i t i v ec r i t i c a l i t yc o e f f i c i e n t

The system pr oposed f or cont i nuous r emoval of t he v o l a t i l ef i s s i o nproduct f r o mt he core i t s e l fhas a r e t ent i o nt i me of some hundr eds of seconds onl y Each pr ocessi ngmechani sm whi ch operatesout of core s l i m t e d by t he amount of mol t en fue l bei ng pumped f r o mt he cor e t o t he pr ocessi ngpl ant Thi s amount , due t o t he hi gh c api t a l c os tof t he fue l and hi gh operat i onc o s t scannot be greatert han t h a t whi ch gi ves a fue l i n- core dwel l t i me of about one week Even w t h a day dwel l t i me , t h a ti s , i fa f t e rone day t he f ue l goes t hr ough t he pr ocessi ng p l a nt , no accept abl e s o l u t i o nt o t he I - 131pr obl em s obt ai ned s i nce t he a c t i v i t yof t h i s nucl i de s onl y di mni shedby one or der of magni t ude

Onl y d i r ec t i n - c o r er emoval gi ves t he dwel l t i me i n core as l owas some hundr eds of seconds

Del ayed Neutron E m t t e r s



Some of t he shor t - l i vedi odi neand bromne (perhaps a l s oa r s e ni c ,t e l l u r i u m i sotopes ar e t heprecursorsof t he del ayedneut r ons

Ot her possi bl e nuc l i des i ncl udeAs- 85, Kr - 92 -9 3 , Rb- 92, -9 4 , Sr- 97, - 9 8 , Te- 136, - 137 ,Cs- 142,- 143 The r emoval of t h e sedel ayed- neutr onprecursors f r o mt he core reduces t he val ue of betwhichi sal r eady l ower f or Pu- 239 than f or U 235 Thus one must t r a d eof f bet ween rapi d r emoval of t hehazar dous I - 131, and a dwel l t i me i n t he core f or t he del ayedneutron precursors I - 140, I - 13 9,I - 138,I - 137 and t he appropr i at ebromne i sotopes

I n t h i s case t he mean dwel l t i me of i odi ne i n t he s t eady s t a t ereactor i s about 100 seconds t canbe seen that t he a c t i v i t yof i odi nef or a 2 5 GWt reactor i s of t he order of onl y 10 k i l oc ur i e s f orseconds) a c t i v i t yof approxi mat el y or f or 1000 second ext racti on r a t e

Thi s amount of pl u toni umi s of t he order of 10 4 r el a t i v e t ot he amount of pl ut oni umf i s s i o nedi nt he same t i me (approx 10 4 mol Pu/ s) However , i t s t i l lhas t o be recovered, whi chunf ort unat el ymkes t he pr ocessi ngmor e compl i cat ed

Last but not l e as t i s t he i n- coregas ext ract i onof t wo other el ement s :

oxygen, i n t he f o r mof O, f r o mi mpur i t i es i e PuOCI )

sul phur , i n t he fo rmof S, f r o mt he nucl ear r e a ct i o n35 CI n , p35S

afety

The mol t en chl ori des r e a c t o rseem t o be a r e l a t i v e l ys a f e systemdue t o t he f ol l ow ngreasons

an ext r emel y hi ghnegat i ve t emperat ure c oe f f i c i e ntof r e a c t i v i t y,s i nce duri nga t emper at ur er i s e pa r t of t he l i qui dfue l i s pushed out of t he core i n t oa n o n - c r i t i c a lgeomet r y buf f ertank The dumpi ng of f uel i ncase of an i n ci d en ti s a l s opossi bl e i n an ext r emel y shor tt i me

Precursorsof del ayedneut r ons f or Pu- 239 f as t f i s s i o n

Group H a l f - l i f et12 s

Fr act i on Probabl e Nucl i de

52 75 3 8 Br - 87

2 22 79 28 0 I 137 Br 86

3 5 19 21 . 6 I - 138, Br - 89

4 2 . 09 32 8 I - 139, Br - 90

5 0 549 10 3

6 0 216 3 5



i n a more seri ous i nci dent when t he fu e l t emper at ur e i ncr eases t o 1500- 1700 ° dependi ngon e x t e r na lpressure t he fu e l begi ns t o bo i l The vapor bubbl es gi ve r i s e t oa new anduni que,very hi gh negati ve f u e l voi d e f f e c t

t he l eakage of f u e l t o t he cool ant i s pr obabl y not a seri ous pr obl embecause the cool ant i scont i nuousl yprocessed

l eakage of cool ant t o t he fu e l f or t he same reason cannot cause l ar ge pr obl ems provi dedt he l eak r emai ns smal l

di sadvant age of a mol t en fu e l reactor i s t he need t o i n i t i a l l yheat t he s o l i d i f i e df uel i nanon c r i t i c a lgeomet r y w t h e x t e r na lpower e g f r o mt he e l e c t r i c algr i d) Thi s pr obl emhas been f u l l yover co me i n t he case of t he mol t en f l u o r i d et her mal reactor Oak Ri dgeNati onal Labor at or y

Anal ysi s of Acci dentSi t uat i ons

Cont i nual r emoval of v o l a t i l ef i s s i o nproducts f r o mt he s a l t sduri ngoperat i onel i mnat es se ve r a lobnoxi ousspeci es f r o mbei ng present i n an acci dent Many of t he r emai ni ng hazar dscoul d s t a y i n t hes a l t Thus, no acci dent can occur whi ch corresponds i n s e v e r i t yof r adi oac t i vi t yt o t he mel t down ofs o l i df u e l syst ems The maj or concernthen becomes tha t no pr i mar y ci r c ui t f ai l ur el e adt o c r i t i c a lmas ses f o r m n g

Smal l Leakages Leaks bet ween core and bl anket pose no seri ous chem cal t h r e a tas t he s a l t sar e compat i bl e Howeve r , other f a c t o r si nf l uencewhet her t he pressure di f f erenceshoul d f o r c ecores a l t l eaks i n t o t he bl anket or vi ce versa

H gher t emper atur es i n t he core s a l t may producehi gher vapor pressures t h e r et han i n t he bl anket

The core s a l t a l s oc i r c u l a t e sunder pump pressure whi l e the bl anket s a l t need not I f a r e ser ve t ankautomat i cal l yr epl aced f u e l s a l t l eaki ng i n t ot he b l a nk e t ,t he sys temcoul d si mul t aneousl yappr oachs u p e r c r i t i c a l i t yand hi gh t emper at ur e, a strong t emper atur e coeff i c i entnot w t hs tandi ng The hi ght emper at ur e coul dfurther abet t he d e t e r i o r a t i o n I n c o n t r a s t ,bl anket s a l t l eaki ng i n t ot he c or e woul donl y dampen t he c r i t i c a l i t y however , t h i s coul dr es ul t i ndegr aded syst emper f or mance

n anomal ous r i s e i n concent r at i onof 233Uor f i s s i o nproduct i n t he b l a nk et ,or a r i s e i nt emper at ur e there due t o i ncr eased f i s s i o n s ) or a drop i n core s a l t pressure woul d s i g na lc o r e - t o -bl anket l eakage Leakage of bl anket s a l t i n t ot he core woul d decrease t he core mean t emper at ur e andbl anket s a l t pressure

The secondar ycool ant c i r c u i tshoul d be pressur i zeds l i g h t l yhi gher above t he pr i mar y one, and t het e r t i a r yeven hi gher Thi s wi l lcause l e s s a c t i v ecool ants l i k ehel i umor l e ad t o l e ak i n t ot he mol t ens a l t He i n e r tand t he s a l t cl eanup system whi ch al r eady separates t he f i s s i o nproduct gases, woul dremove hel i umas wel l Lead i nt e r a ct sw t h ni c kel - bear i nga l l o y s ,but not w t h Mo or gr aphi t e Tr apsat c e r t a i npoi nt s i n t he c i r c u i twoul d l o c a t et he p o s i t i o nof l e ad l eakage

The cont ai nment bui l di ngwi l l catch l eakage of v o l a t i l ef i s s i o nproducts f r o mt he pri mar y c i r c u i tor bl anket t o t he a i r , s i m l a r t o MSRE w t h appr opr i at edet ecti onand l e ak - t i ghtba r r i e r s

Loss of Fl ow Leaks, pi pe break, heat exchanger pl uggi ng, and pump f a i l u r ecan al l reducef l o wi n t he pr i mar yc i r c u i t I n mos t events the reactor

s h u t s down and t he f u e l drai ns t o a s a f e t yt ank;



there f i s s i o npr oduct decay and del ayed neut r on- i nduced f i s s i o ncont i nue t o gener at e hea t , but t he hi ghcapaci t y of t he s a l t r e s t r a i n st he t emper atur e r i s e

The e f f e c tof a si ngl e pump f a i l u r edepends upon t he pri mar y c i r c u i tar r angement

Wt h s i n g l epumps per channel f a i l u r eof one pump woul d shut down one whol e cor e channel The fue l s al t i ntha t core channel mus t then drai n out t o s t o pf u l l power pr oduct i on i n i t Subsequent r epl acement byvoi d, b l a nk et ,or c a r r i e rs al t woul d cause a l a r gel o s s of r e a c t i v i t ythereby s h u t t i n gdown t he r eact orunl ess

l The separ at i on bet ween channel s was such tha t they wer e i ndi vi dual l y near c r i t i c a l ,and

2 M s s i n gr e a c t i v i t ycoul d be added t hrough enr i chment enhancement

Then one coul d cont i nue operati on on a r educed s c al e ,e. g 6/ 7 f or s i xout of seven channel s s t i l loper at i ng, u n t i la mor e oppor t une t i me occurr edi n whi ch t o drai n t he whol e core and r epl ace

mal f unct i oni ng equi pment

W t h mul t i pl e subchannel s per cor e channel , each w t h pumps and exchanger s , f a i l u r eof onepump s t i l lal l ows pa r t i alr eact or operati on u n t i la b e t t e r t i me f or s hut down and r epai r I f one oper at edt he Pl an B or C subchannel s or t he pl an heat exchanger at l es s t han f u l l e f f i c i e n c y,then t h e i rf u l luse i s a vai l abl ei n t he event of one subchannel f a i l u r e Thi s woul d however , i ncrease out- of - corei nvent or y and c api t a lcosts t hough Shoul d t he cor e t ubes be connect ed i n s e r i e s ,then any i n- coremal f unct i on l e akor pi pe br eak) woul d requi re systems hut down

Shoul d bot h r egul ar and emer gency power suppl y f i l al l pumps woul d f a i l unl es s t hey ar e steamt ur bi ne dri ven However , e l e c t r i c a l l ydr i ven pumps ar e easi er t o i ncl ude i n t he cont ai nment and a l s oe as i e rt o suppl y f or p r e- t e s t i n g,et c I n e r t i awoul d hel p e l e c t r i cpump r un- down r a t e s , or someshort-terma u x i l i a r ysuppl y m ght have t o be pr ovi ded u n t i l f u l l dump of f u e l has t aken pl ace Thef l u i dcoul d a l s odr ai n t hr ough a freeze val ve by gravi t y i n t oa nat ur al - convect i on cool ed t ank whi chhas a n on cr i t i c algeomet r y

I n t he event tha t f l o wceases and core s a l t r emai ns i n p l a c e,the s t r ong negat i ve t emper atur ec oef f i c i ent wi l lcont r ol t he t emper atur e and power i n i t i a lt emper at ure i n cr e a s ewi l ldecr ease d en s i t y,whi ch decr eases r e a c t i v i t yand thereby power , u n t i l some equi l i br i ums t a t ei s r eached MCFR PUst udi es [29] w t h a s i mpl i f i ed r eact or model showed tha t t he t emper at ure r i s eof t he s a l t f or a r e a c t i v i t ys t e pof up t o 1 shoul d be l es s t han 300°C f or pumps f a i l i n gout of 8, l es s t han 230°C

I n s ummar y, i t appear s tha t r eact or s t a b i l i t yconcer n over out-of-core i nvent ory may pr ecl ude t he

use of out-of-core subchannel s as wel l as di c t at e s er i e sconnect i on of t he cor e channel s Thi s meansdesi gni ng t he system f or hi gh r e l i a b i l i t yt o m n i m z e shut down and f or r api d r e p ai rof heat exchanger s ,pi pi ng, and pumps when shut down does occur Rapi d r e p ai rwi l l ent ai lexpedi ent r emoval of al l t hecore s al t f ol l owed by a s a l t f l ushi ng of al l r a d i o a c t i v i t yf r o mt he system The strong t emper at ur ec o e f f i c i e n tshoul d d i s p elany c r i t i c a l i t yacci dent concer ns

Structural Fai l ure Fai l ure of t he tubes separ at i ng core and bl anket woul d l ead t o no chem calor compat i bi l i t y pr obl ems Di l ut i on of t he core s a l t w l l r educe r e a c t i v i t y; onl y i fcore s al t wer er epl eni shedas i t ent er ed and di spl aced t he bl anket, coul d a r e a c t i v i t yi ncrease occur ven then t hesystemcoul d accommodat e t emper at ure r i s ef r o mmoder at e s a l t a ddi t i o ns ,as ampl e mar gi n e x i s t sabove operati ng t emperat ure on a s h o r tt e r mba s i s The l i m tt o t he per m ss i bl e r a t e of such s al taddi t i on needs t o be establ i shed



Vessel f a i l u r ewoul d requi re rapi d dumpi ng fromboth t he c i r c u i tand t he catchpots Dump tanksshoul d probabl y be si zed t o contai n t he contents of one secondar y cool ant c i r c ui t aswel l as al l coreand bl anket s a l t Rel i ef val ves on t he secondary systemw i l lprotect t he pr i mar y c i r c u i tf r o mpressuri zati on r e s u l t i n gf r o m a maj or steam gener at or f a i l ur e i n t ot he secondary system

I n t he event of a maj or c i r c u i tf a i l u r e oper at i ng pr essur ewoul d pl ay an i mpor t ant r o l ei n t hesubsequent f a t e of t he f i s s i o nproducts and t he cont ai nment The mol t en s a l t s t hemsel ves exhi bi t l owvapor pressures Al t houghhi gh pumpi ng l o s s escan cause pr i mar y c i r c u i tpressures up t o 46 p s i l e a dsecondar y cool ant a c t s e s s e n t i a l l yl i k ea hydr aul i c system wi th l t t l stored ener gy M s s i l ef or mati oni s therefore unl i kel yand t shoul d be possi bl e t o demonst r at e a cont ai nment whi ch wi l lnot bebr eached f r o m t h i s cause

Wth a hi gh pressur e hel i umcool ed sys temone must ask whet her an acci dent m ght aer osol i ze t hecore s a l t However a pr oper l y desi gned r eactor vessel coul d wi t hst and t he f u l l hel i umpressure f r o masevere rupture bet ween t he cool ant and pr i mar yc i r c u i t s Thus r el ease of a c t i v i t yt o t he reactor

cont ai nment c e l l woul d not occur except under a si mul t aneous doubl e f a i l u r e

The c e l l i t s e l f s smal land can economcal l y be mde i n t he f o r mof a prestressed vessel t o wi t hst and m s s i l e damge and t oac t as an addi ti onal ba r r i e rt o f i s s i o npr oduct r e l e a s e i na l l ow pressure bui l di ngcont ai nmentwoul d pr event r e l e as ef r o msmal l l e ak si n t he e a r l i e rcont ai nment stages

Emrgency ool i ng Unl i kes o l i df u e l mol t en s a l t can qui ckl yt r a n s f e ri n t oa geometr i cal l ys a f e tank Gr avi ty can provi dea f a i l s af et r a n s f e rmet hod f r o mreactor t o hol di ngtank a pi pewher ei n t he s a l t s nor mal l y kept frozen woul d open natural l y upon l o s sof e l e c t r i cpower

I n t he t a n k t he s a l t wi l lc i r c u l a t enat u r al l yas heat f r o mf i s s i o npr oduct decay t r a n s f e r st hr oughtube wal l s t o ai r convected by natural d r a f t t ower s Ot her wi se pressure woul d bui l d up f r o m s a l tvapor i zat i on The absence of mechani cal movi ng par t s wi l lmke t h i s whol e system hi ghl y r e l i a b l e;

mul t i p l i c i t ycoul d add even f u r t h e ri n t e g r i t y forced d r a f tsystem woul d pr obabl y l ayout mor ecompact l y and cheapl y

second cool i ng opt i onwoul d c i r c u l a t en a t u r a l l ya l owmel t i ng poi nt s a l t or NaK t hr oughU t ubes i n t he tank t o boi l i ng wat er heat exchanger s Ai r cool ed condenserss i t u a t e di n a nor mal orforced d r a f tstack woul d condense t he st eamf or med Al t e r n at i v el ythe heat coul d t r a ns f er di r ec t l yt oa l ar ge boi l i ngp o ol t h usac commodat i ng decay heat f or a protracted per i od wi t hout mkeupCondenser s or mak e up wat er woul d be provi ded f or conti nuous oper ati on

c a t c ha l ls a l t bed bel ow t h i s apparatus woul d serve as a backup f or any l eaks or br eaks Theheat of s a l t f or mati on woul d gr eatl y ai d i n absor bi ng decay ener gy n i ndependent cool i ng system

m ght remove decay heat The bed woul d a l s od i l u t et he fu e l s a l t Pr oper choi ce of t ank di ameterwoul d i nsure s u b c r i t i c a l i t y

Recover y f r omemer genc y tanks or beds woul d requi reh ea t e r s dr a i n sand pumps Wen c a r r i e ror bl anket s a l t s added f or d i l u t i o nand/ or heat absor pti on by l a t e ntheat of f ormati on a met hod t osepara te out the dump s a l t woul d a l s obe needed

ompari son of SRs t o Other Reactors MSRs shoul d be b i o l o g i c a l l ys a f e rbecause

The p l a ntconti nuousl y r emoves v o l a t i l ef i s s i o nproducts

The fu e l s al r eady mol t en and i n coni act w t h mat er i al s desi gned f o r tha t condi t i on



The r emoval of v o l a t i l e sf r o mt he pr i mary c i r c u i ts t r equi r es at t e nt i ont o t h e i rpresenceel sewher e i n t he p l a nt However i t shoul d not be d i f f i c u l tt o i nsure t he i n t e g r i t yof a st orage medi umbel ow ground Af t er a s u i t a b l edecay per i od some of t he gases may be rel easabl e t o t he at mospher e

I n t he event a pump f a i l sor ot her f l o w l o s s occurs t he onl y concern i s tha t decay heat mghtbui l dup vapori zat i on pressure However t he same c o i l swhi chpreheat t he f l u i dcoul d a l s ocool t hef l u i d

Prec i pi t at i on out of Eut ect i c M xtures Af t er t he t emper at ure of a s a l t mxture f a i l s t o t hes o l i d i f i c a t i o np oi n t ,t he composi t i on of l i q u i dchanges s l i d i n gal ong t he l i qui duscurve as c r y s t a l sseparat e out W t h l ow i n i t i a lU mol ar c o n t e n t ,cool i ng pr e c i p i t a t e sout NaCI c r y s t al s ,t her ebyenri chi ng t he f l u i di n UCl3 W t h hi gh i n i t i a lUCl3 mol ar c o n t e n t ,cool i ng produces UCl3 C r y s t a l sandNaCI - enri ched f l u i d I n ei t hercase t he l i q u i dmgrates t o t he nearest e u t e c t i cpoi nt n ad i r composi t i onand causes a concent rat i on of U 3 Thus one must consi der possi bl e c r i t i c a l i t ys i t u a t i o n sand desi gngeomet r i es t o prevent t hem Probabl y p r e c i p i t a t i o nof UCl3 c r y s t a l sf roma UCl 3- r i c h f l u i d s t he

l es s - s er i ouscase

Boi l i ngOf f of Sal t M xtures I n t he event tha t t he c a r r i e rs a l t had a boi l i ng poi nt much l owert han that of t he a ct i ni d e c hl or i des ,one coul d postulate a p o s i t i v et emper at ure coef f i ci ent cont ri but i oni n t hat t emperat ure regi on For t unat el y c a r r i e rs a l t sappear t o be l e ss vol a t i l et han acti ni de c hl o r i d es

ontai nment Sol i d fu e l pl a nt sgeneral l y f eat ure t r i p l econt ai nment : fu e l el ement reactor v es s e l ,and then t he cont ai nment bui l di ng The M FR wi l lf eat ure reduced FP r a d i o a c t i v i t ydue t o cont i nuousgas cl eanup but i t wi l li nherent l y have onl y doubl e cont ai nment of pi pi ng and a bui l di ng econdradi at i on hazard a r i s e sf rom a c t i v a t i o nof t he secondary cool ant and near by equi pment by del ayedneut r ons i n t he pri mary c i r c u i t

To f u r t h e rcont ai n t hese hazards a l ow- pr essur e l e a k - t i g h tmembrane mght be f or med around t hewal l s , f l o or sand cei l i ng of t he reactor syst em Thi s membrane can a l s of o r mpar t of t he duct i ng f ort he i ne r t gas ci rcul ati on r equi red t o cool t he concret e s t r u c t u r eand shi el di ng and i n h i b i tvesseloxi dat i on Heat l o s se sw t h i n s u l a t i o nr e s t r i c t i n gt he concret e t emper at ures t o bel ow 70°C woul d beabout wat t s/ m w t h 40 cm of i n s u l a t i o n Thi s woul d equate t o about 3 o ta l heat r emoval bywat er or ai r cool i ng

The mai n bui l di ng woul d c ons t i t u t e t het e r t i a r ycont ai nment I t Svol ume must be s u f f i c i e n tt ocont ai n t he st ored energy of any gases present I n t he l eadcool ed desi gn t h e s eare cover gas vol umesat l ow t o moderat e pressure The hel i um cool ed vers i on may requi re a l a r ge rout er cont ai nmentvol ume and/ or i nt ermedi at e prest ressed concret e cont ai nment Sec 3 . 6 . 3. 3

Mol ten Sal t ombust i on Support Mol t en s al t i t sel fdoes not burn but w i l l supportcombust i on w t h s o l i d ssuch as wood coke paper p l a s t i c s ,cyani des c hl o r a t e s ,and ammoni um s a l t sand w t h a c t i v emet al s such as al um num sodi um and magnesi um Wat er f rom spray s p r i n k l e r sorl ow- vel oci t y f og nozzl es provi des good f i r eprotecti on

Resi st ance t o ext ernal t h r e a t

One can post ul at e a number of scenar i os wher ei n e x t e r na lexpl osi on i mpact t h r e a t e n st he reactori n t e g r i t yd i r e c t l yor t hrough a l oss- of - cool ant acci dent These coul d i nvol ve ground or a e r i a lbombspl anes and space r e - e n t r yp r o j e c t i l e s e. g met eors m s s i l e s ,space l a bo r a t o r y ,by e i t he racci dent ori nt ent i on n i n d i v i d u a l ,a subnat i onal group or anot her count r y mght i n t e n t i o n a l l yi n i t i a t e Nature



t h r e a t e n sw t h ear thquakes, tornadoes, and dam breaks

I n many or most of t h e se s i t u at i o nsone coul danti ci pate t he danger ost reactors al r eady l i ebel owgr ound l e ve l S t i l lthe vessel s genera l l ysi t hi gh enough t o be rupture-prone t o strongexpl osi onsor i mpact s Such an i nci dent coul d r el ease vol at i l i z edf i s s i o nproducts and acti ni des ofconsequence gr e at l yexceedi ng a si mpl e bomb or ot her i n i t i a t i n gevent

To protect agai nst these t h r e a t san M FR coul d uni quel y t r a n s f e ri t s f uel t oa storage t a nk l ocatedr emot el y under addi t i onal e a r t hor i nan otherw se har dened bunker

Fi s si onr e a c t o r si nherentl y i nduce hi gh l ev el sof r a di o ac t i v i t y e r r o r i s tcoul d del i ber a t el yrel ease radi oacti ve gases and, by means of expl os i ve devi ces ,radi oacti veaer osol s Al t houghan MSR

pl ant conti nuousl ypur ges i t s f u e l much of t he probl emr emai ns t he same amount of f i s s i o nproductshave s t l lbeen gener at ed per MW and mus t eventual l y be di sposedof transported f r o m i n- pl a nts a f estorage t o some f i n a ls af e s t or age Onl y sem per manent storage at t he MSR s i t e can al l ev i a t et he

t r a ns po r t a t i o nr i sk r el at i ve t oother r e a c t o r s But even then such a hi gh f i s s i o nproduct concent r ati onmght a l s oa t t r a c tsaboteurs

I n c o n t r a s t a f usi on reactor produces onl yt r i t i u mwhi ch s concei vabl ydi spersabl e I n- p l a ntrecycl i ngf u r t h e rmti gates t he probl em However , t he onl y near-termeconomcal f usi on reactor i sproj ected t o be t he hybr i d whi ch wi l lpr oduce weapons- gr adef i s s i l efu e l agai n

Effec t s of Neut ron I r r adi at i on upon Mol ten Sal t hemstry

E ff e c tof Chemcal S t a b i l i t yupon Corr osi on

Usi ng t he mol t en s a l t f u e l as t he pr i mar y cool ant of a nucl ear reactor presents many novelprobl em i n both reactor desi gn and sys temchemstry The success of t he ORNL Mol t en S al t React orPr ogr amshows tha t t can be done at l e as t up t o t h ei rpower l e v e l s Exper i ence t her e al s or eveal edthat t he chemcal s ta te s often behave as i n equi l i br i um Thi s al l ows much progress t owar dsunder st andi ng i nt e r a ct i o nsw t hi n t he s a l t chemcal s t a b i l i t yand bet ween t he s al t and t s envi r onment corr osi on) si nce many of t he e q u i l i b r i aar e gr oss l ypr edi ctabl e

The f r e eenergy of f ormati on of t he compounds , G meas ur es t he chemcal s t a b i l i t yof t he s a l t ss p e c i f i c a l l yt h e i rabi l i t y t or e s i s t f o r m n g other compounds whi ch p r e c i p i t a t eout Taube has deducedt he t emper at ur e- dependent G f or s a l t sof i nt e r e s t[82]

Candi dat e r e a c t a n t si n t he sys temwhi ch t h r e a t e ns a l t s t a b i l i t yar e

At mos pher e consti tuent s oxygen, water , and car bon di oxi de

S t r u c t u r a lm ter i a l s

3 Fiss i on productsand other mut ant s

Radi ol ysi s al s o af f e ct ss a l t s t a b i l i t y

Chemcal corr osi oni nvol ves several sci ences Physi cal chemstry and metal l urgy descri be t hephysi cal , chemcal , and mechani cal behavi or Ther modynam cs r eveal s t he spont aneous d i r e c t i o nof a



react i on and whet her or not cor r os i oncan occur. El ec t rochem st r y descr i bes el ec t rodek i n e t i c s: t hed i s s o l u t i o nand pl at i ng cut of d i f f e r e n tmateri al s i n e l e c t r i c a lcontact.

Transmutati ons of Sodi um and Chl or i ne

The hi gh neut ron f l u xw i l lcause consi derabl e t r ansmut ati onsi n t he s a l t vi a t he f o l l o w n gr e a c t i o ns

35Cl n, y 36Cl bet a- , 3. l x10 5 years - > 38Ar vol at i l e

37Cl n,y3 8Cl be ta - ,37.3minutes8Ar vo la t i le

' 35C n, p) 35S bet a - , 8 7 days) - + 35C1

2 3N a ( n , y )2 4N a(bet a- , 1 5h )_ _ +2 4M g ( n , y ) 5 M g ( n , y) 26 M g ( n , y) 2 7 M g (be t a - ,9m i n ) 2 7 A l.

The b u i l d - i nof sul phur wi l la f f e c tt he mol t en fu e l chemstry, as di scussed be l ow Magnesi um andal umnum t h r e a t e nt o physi cal l yc l u t t e rup t he system

Chemcal Behavi or of Radl osul phur Obtai ned by 35Cl n, p)35S Duri ng I n - P i l eI r r a di at i on[ J a75]

The r a t h e r l a r g econcent r ati onof sul phur f or med by 35Cl n, p35S r eact i on i n t he mol t en chl ori dessys t emproposed f or t he f a s t reactor makes i t necessary t o obt a i n t he f u l l i nf or mat i onon t he chem calbehavi or of t he r adi osul phur. The mos t recent s t u di e son t he chem cal s t a t e sof radi osul phur obt ai nedby i r r a d i a t i o nof a l k a l ichl ori des have shown t he compl exi t yof t h i s probl em

To obt ai n new data on t he behavi or of radi osul phur we have i nvesti gat ed t he i nf l uence of t he t i meand t emperat ur e of i r r a d i a t i o nand of p o s t - i r r a d i a t i o nheat i ng on t he chem cal d i s t r i b u t i o nof t hesul phur

Experi ment Desc r i p t i o n. Sodi um chl ori de Mer ck reagent) was heat ed f or 60 hr at 200 °Ci n an oven i n vacuo The dri ed sampl es of 100 mg seal ed i n evacuat ed 10 4 t o r r quartz tubes , wer ei r r a d i a t e dnear t he core of t he Saphi r swmmng pool reactor at a nom nal neutron f l u xof 5 x 10 1 ncm 2 s-1 and est i mat ed t emperat ur es of 150- 190 °C After i r r a d i a t i o nt he sampl es were kept f or 8 dayst o al l owt he decay of Na

The Met hod of 35S- Speci es Separ a t i on-The cr ushi ng of t he i r r adi a t edampoul e wasmade i n a speci al devi ce f r o mwhi ch t he ai r was removed by pur gi ng w t ha ni t rogen streamcont ai ni ng 10 ppm of oxygen After cr ushi nga gentl e streamof ni t rogen was al l owedt o - f l o wf orabout 10 mn The gases evol vedwer e col l ectedi n cool ed t r a p s. The i r r a d i a t e ds l a t was di ssol ved i n2 N o l u t i o ncont ai ni ngc a r r i e r sof S CNS- 5O 2 , SO42- . Duri ng di ssol ut i onoxygen was notcompl etel yexcl uded al t hough ni t r ogen gas was passed conti nuousl y t hr ough t he system Ther adi osul phur f ound i n gaseous f o r mwas deter m ned as bar i umsul phate. For t he 3 5S- speci esseparati ont he chem cal met hod descri bed recent l y by Kasrai and Maddock was used The radi oacti vesampl eswer e count ed under a t h i n w ndow Gei ger count er Al l meas ur ement s wer e made i n dupl i cat e w t hand w t hout Al - absorber

Pos t - i r r adi at i onHeati ng- - Theseal ed i r r a d i a t e dampul es wer e heat ed i n an e l e c t r i covenat 770°C f or 2 hr or at 830°C f or about 5 mn and t hen cool ed and cr ushed i n a cl osed systemunder



a stream of ni t r ogen

Ef f ect of Length of I r r adi at i on Ti me S2 r emai ns t he preponderant f r a c t i o ni ndependent of

t he i r r a d i a t i o nt i me. For mat i on of S i s i ndi cat ed by charge conservati on duri ngt he C1 n ,p ) 35Sreacti on Al ternat i vel yi t can be supposed tha t reducti on of sul phur t a ke s pl ace by capture of el ectr onsdue t o t he di schar ge of F- centers The presence of S i n t h i s oxi dat i on s t a t e i n t he l a t t i c ei s no l ongercontested The precursors of hi gher f or ms may be S as a r e s ul tof an el ectron l o s s f r o mS

However , t he i n t e r a c t i o nof chl ori ne e n t i t i e sf or med by i r r a d i a t i o nw th radi osul phur t o f o r mspeci es asSCI , SCl2 SCIZmay be an i mpor t ant mechani sm n f o r m n g t he precursors of sul phat e and s ul ph i t e.

Duri ng l onger i r r a d i a t i o n ssome of t he sul phi de i s converted i n t ohi gher oxi di zedf or ms Thi smay be a consequence of radi ati on- produceddefects w t h oxi di zi ng character e. g. V- centers or d e r i -vat i ves I t i s possi bl e that t he concentr at i onof defects responsi bl e f or r educti on of t he sul phurdecr eases by anni hi l at i onwhen new t r a p sare f or med. The oxi dat i onof radi osul phur w t h i ncrease ofradi ati on damage concentr at i on may a l s obe due t o t he reacti on of r e c oi lsul phur w t h chl or i ne at oms .

The presence of O f i n t he c r y s t a lmust not be negl ect ed I t has been suggested tha t r a d i o l y s i sof OH

can be responsi bl e f or accel erati ng t he oxi di zi ng process

Ef f ect of Pos t - I r r a di at i onHeati ng The e f f e c t of p o s t - i r r a d i a t i o nheat i ng i ncl udi ngmel t i ngcan be seen i n Tabl e 5. Compari sons bet weenheat ed and unheat ed sampl es ar e made f or i r r a d i a t i o n sof 2, 12 and 24 hr For 2 hr i r r a di a t i on, r es ul t son sampl es heat ed at a t emper at ure bel ow t he mel t i ngpoi nt of NaCl ar e al so presented As i s seen, on he at i ng,a part of t he r adi osul phur i s f ound i n av o l a t i l ef o r m The v o l a t i l er adi osul phur appears at t he expense of S0 and hi gher oxi dat i onf or ms Ther e su l t sshow tha t w t h t emper atures above t he boi l i ngpoi nt of sul phur and above mel t i ng poi nt ofNaCl t he S and S and/ or SxCl yr ecei ve s u f f i c i e n tk i n e t i cenergy t o mgrate t o t he surf ace or even t oescape f r o mt he c r y s t a land be col l ected as v o l a t i l er adi osul phur However , t h e r eare some di f f erences

i n t he35S chem cal d i s t r i b u t i o non heat i ng bel owand above t he mel t i ng poi nt of NaCl exper i ments2 - 3 ) I t seems that f or r e l a t i v e l yshor t per i ods of i r r a d i a t i o n 2 hr onl y the sul phate and s u l p h i t e

precursors account f or t he v o l a t i l er adi osul phur f r a c t i o n For a l onger t i me of i r r a d i a t i o n ,on mel t i ngt he S val ue decr eases t o about 2 and t h i s corresponds t o an i ncrease i n t he v o l a t i l er adi osul phur exper i ment s 5, 7). However , a smal l and p r a c t i c a l l ycons t ant yi el d of S i s f ound i n t he mel t a f t e rl onger i r r a d i a t i o n.

Fi ssi on Pr oduct Behavi or i n t he Fuel

The f i s s i o nof PuCl3 causes t he f ormat i onof two f i s s i o nproducts FP1 and FP2 and t h r e eat oms ofchl ori ne PuCl3 n , f FP, FP2 3C1 For t he f i s si oni ngof 100 at oms of Pu t he f o l l ow ngbal ancehas been suggest ed 100 PuCl3 n , f - 0 008 Se gas) 0 003 Br gas 0 942 Kr gas) l 05RbCI 5 49 SrCl2 3 03 YCl3 21 5 ZrCl3 0 29 NbCl 5 ? ) 18 16 MoCl2 0 28 MoCl3 401 Tc metal 31 45 Ru met al . 73 Rh met al 12 66 Pd met al . 88 AgCl 0 66 CdCl 2 0 06 I nCI 0 324 SnCl2 67 SbCl3 7 65 TeCl2 6. 18 I gas 21 23 Xe gas 13 34CsCl 9 50 BaCl2 5 78 LaCl3 13 98 CeCl3 4 28 PrCl3 11 . 87 Nd l 3 l 44 PmCl3 3 . 74

SmCl 3 0 60 EuCl . 0 03 CdCl 3 .



Tabl e 5 Effects of pos t- i r radi at i on heati ng

Expt

I rr ad Post i r rad

S2 S S0 2- S0 2- ` S vol at i l et i me t r e a t m e n t 4 3

2 hrs no 73 . 1 ± 0 . 4 9 . 8 0. 8 16 . 9 ± 0 . 8 0 . 01

770 0C75 . 4 2 . 8 5 . 3 0 . 3 3 . 6 2. 3 15 . 4 1 . 12 hrs

3 830oC 77 . 2 2 . 0 11 . 0 0. 8 6 . 6 2. 5 5 . 0 ± 1 . 45 mn

4 12 hr s no 67 . 5 n . 7 12 . 1 0 . 1 20 . 4 ± 0 . 6 0 . 01

830 007 . 15 1 . 9 18 . 9 7 . 65 mn

6 24 hrs no 6 4. 4 2 . 5 11 . 9 ± 0 . 5 23 . 7 ± 2 . 0 0 . 01

830 0C68 . 2 ± 3 . 4 2 . 3 ± 0 . 5 21 . 4 ± 2. 3 7 . 9 ± 0 . 75 mn

Exp 5 = 4 .3 1012 n C A -1

Expt 6 7 = 5 0 1012 n cm 2 s

` Sul phi te f r act i on i s l ess t han 5 i n our exper i mentsand al ways l ower t han sul phat ef r act i on



From t he e a r l i e rpubl i shed data Chasanov, 1965; Har der et al 1969 ; Taube, 1961) i t appearst ha t t he pr obl emof t he chemcal s t a t e oxi dati ons t a t e i n t h i s chl ori de medi um f or t he f i s s i o nproductel ement const i t uent requi res further c l a r i f i c a t i o n

From a si mpl e consi derat i on i t seems t h a t the f r eei ng of chl ori ne f ro m t he f i ssi oned pl ut oni umi scont rol l edby t he f i s s i o nproduct el ement s w t h st andard f r e eent hal py of f ormat i on up t o 1- 20 KJ / molof c h l o r i n e ,t h a t i s up t o mol ybdenum chl ori de The mor e nobl e met al s such as pal l adi umt echneti um r ut heni um r hodi umand probabl y t e l l u r i umand of course nobl e gases : xenon, krypt on pl usprobabl y i odi ne and bromne, r emai n i n t h e i rel ement ar y s t a t ebecause of l ack ofchl or i ne Mol ybdenum as a f i s s i o npr oduct w t h a yi el d of 18 r om200 l l f i s s i o nproducts may r emai n i np a r t i n metal l i c f o r m Si nce mol ybdenum a l s opl ays t he r o l eof s t r u c t u r a lmat eri al t he corr osi onpr obl em of t he me t a l l i cmol ybdenum or i t sall oys ar e str ongl y l i nked w t h t he f i s s i o nproductbehavi or i n t h i s medi um

The possi bl e reacti on of UCl and PuCl w t h MoCl 2 r e s u l t i n gi n further chl ori nati on of t he

a c t i n i d e s - t r i c h l o r i d e st o t e t r a c h l o r i d e sseem, f or PuCl very unl i kel y G1000K450 kJ /mol Cl ) but t h i si s not so f or UCl

A r a t h e rseri ous pr obl ema r i s e sout of t he possi bl e r e ac t i o nof oxygen and oxygen cont ai ni ngcompounds e g wat er ) w t h PuCl and UCl whi ch r es ul t s i na p r e c i p i t a t i o nof oxi des or oxychl o-r i d e s The cont i nuous processi ng may permt some cont r ol over t he permssi bl e l e ve lof oxygen i n t hee n t i r esystem as wel l as t he cont i nuous gas bubbl i ng sys temwi t h appropri at e chemcal reduci ng agent

Corr osi onof t he s t r u c t u r a lma t e r i a l ,bei ng mol ybdenum s a l s ostr ongl y i nf l uenced by t he oxygencont ai ni ng substances, a protecti ve l ayer of mol ybdenum however , may be used on some s t e e lmateri al s usi ng el ect rodeposi t i on or pl asma spr ayi ng t echni ques

Not e t h a t al l these consi derat i ons have been based on st andard f r e e ent hal py: but even a change i nt he t her modynam c a c t i v i t yf ro m= t o = 001 whi ch means a change i n f r e eent hal py of 14kJol

t h u s appears i n s i g n i f i c a n tas f ar as t h e s erough cal cul ati ons go

The most i mpor t ant react i ons i n t he f e r t i l ema t e r i a lar e

f i s s i o nprocess : UCl - - *f i s s i o nproduct s 3C1

oxi dati on process : UCl 1/ 2Cl 2 UCl 4; 250K 25kJ / mol

di sproport i onati on: UCl UCl - 3UCl 4 Um

Structural Mat er i al s

To f i n dmateri al s of s u i t a b l estrength and endurance one must a n t i c i p a t et he envi r onment and t heresponse of materi al s t o i t Envi r onment i ncl udes r a di a t i o n,t emperat ure, pr es sur e, f l ui dcomposi t i on,chemcal a dd i t i v es ,condensat i on, and vapori zati on Mat eri al response depends on mechani cals t r e n g t h s ,metal l urgi cal phases, and chemcal i nt e r ac t i o ns corr osi on)

Requi r ement s on t he mat eri al w l l i ncl ude s u i t a b l et hermophysi cal pr o pe r t i e s ,a b i l i t yt o f a b r i c a t eand wel d, product a v a i l a b i l i t y ,and exi stence of pe r t i n en texperi ence f or t he ma te r i a l



General Consi derat i ons and Cr i t er i a

Pl ant Li f e Economcs I n i t i a lstudy usual l y suggests se ve r a leconom cal mat er i al s The

mater i al costi s

i mport ant but t he t r ue i ns t al l edcos t depends a l s oon s i z e,pi pe schedul e systemcompl exi t y j o i n tmake up f abri cati on t echni ques and l abor r a t e s , Downti m and l i f eexpect ancyf uncti ons of t he mater i al response wi l la f f e c tt he ongoi ng mai nt enance c o s t s Fortunat el y metal susual l y have known corr osi on r a t e s

Corrosi on [ 80 26 The mos t i mpor t ant engi neer i ng t a s k i s l i k e l yt o be f i ndi ngmater i al swhi ch r e si s tcorr osi on by f u el and bl anket s a l t mxtures cont ai ni ng f i s s i o nproducts and otheri mpuri ti es Thi s my requi re a t r a d e - o f fwi th system condi t i ons such as l ower i ng t emperat ur edecreasi ng vel oc i t y ,or r emovi ng oxi di zers

Al ternatel y one mght s a c r i f i c esome corr osi on resi st ance f or hi gher s t r e n g t h; a l s o, t hebestmater i al mght not be readi l y avai l abl e The mos t desi rabl e materi al w l l probabl y combi ne moder at e

cost wi th reasonabl e l i f e Somet i mes t he envi r onment condi ti ons change wi th t i me The s t r u c t u r a lmater i al must handl e t h a t or be changed a l s o Exper i ment al l oops under si ml ar reactor oper at i ngcondi t i ons are t h u s i nval uabl e they al l owone t o exam ne actual corroded p i p e,val ves and f i t t i n g s

Many f a c t o r scan a f f e c tcorr osi on some of whi chmy be obscure The quest i ons bel owhel p i neval uat i ng them

What i s t he composi t i on of the corr osi ve f l u i d ?

2 What i s t he concent r at i on s peci f i c gr avi t y ,pH et c. ?

3 What i s t he oper at i ng t emperat ure and pressure?

4 I s water present at any t i me?

5 I s ai r p r e s e n t ,or i s the oppor tuni ty f or a i r - l ea kshi gh?

6 I s t he systemever f l us hed, r i n sed,or drai ned out?

7 I s a s l i ghtamount of corr osi on obj ecti onabl e f r o ma cont am nat i on st andpoi nt ?

8 Has any s pec i f i ctr oubl e or probl embeen exper i enced wi th c e r t a i nmat er i al s?

9 What mater i al s are bei ng or have been used f or val ves and f i t t i n g s ?

10 What were t he comparat i ve l i v e sof t he mater i al s used?

11 Are t h e r especi al f a b r i c a t i o n ,handl i ng or i n s t a l l a t i o npr obl ems?

12 What i s t he est i mated i n s t a l l e dcos t or ca pi t a l i z ed cos tf or t he proj ected l i of t he pi pi ng?

Met al l urgi cal s t r u c t u r emarkedl y a f f e c t scorr osi on resi st ance f ort unatel y i t can of ten be a l t e r e d Physi cal chemstry and i t s vari ous d i s c i p l i n e sare mos t usef ul f or st udyi ng t he mechani s ms ofcorr osi on r ea ct i ons , t hesurf ace condi t i ons of metal s and other ba si c pr oper t i es



Cor r osi on by El ect r ochem cal Attack [ 80] Under chemcal a t t a c k ,met al i o ns l eave anodi careas of the surf ace and ent er i n t ot he s o l u t i o n ,thus di ssol vi ng the surf ace Thi s creates an etcheda f f e c t I n t he sol uti on t hey chem cal l y r e a c t wi t h other el ement s such as oxygen, c hl o r i ne ,et c to fo rmnonmetal l i c compounds ; pl at e- out of t hese darkens t he surf ace wi t h a protect i ve,

passi ve f i l mExampl es i ncl ude ru s t on i r o n ,oxi de l a ye ron al umnum and passi vat i on of s t a i n l e s ss tee l byi mmer si on i n n i t r i caci d

Whi l e they r emai n i n t a c t ,such f i l ms general l y protect t he met al or at l e as tretard f u r t h e rdegradat i on However , hi gh stream v e l o c i t i e s v i br a t i o n,and t hermal shock can al l break t he f i l mconti nui t y he pi ckl i ng of pi pe t o r emove m l l scal e i l l u s t r a t e scont rol l ed cor rosi on by di r ec t at t a ck

Gal vani c a c t i o n,or bi metal corrosi on, exempl i f i es anot her common mechani sm wo di ssi ml armetal s e s t a b l i s han e l e c t r i c a lp ot e nt i a lwhen t hey c o n t a c t ,or connect by an e l e c t r i c a lpat hway, i n t hepresence of a conduct i ng sol uti on e l e ct r o l y t e

I n bol t ed j o i n t s ,such as pi pe f l a ng es ,t he r e l a t i v es i z e sof t he anodi c and cat hodi c areas becomei mpor t ant n anodi c area tha t i s smal l i n r e l a t i o nt o t he cat hodi c a r e a accel erates t he cor r osi on

Where f l anges and b o l t sare di ssi ml ar metal s, t he bol ti ng met al shoul d be cat hodi c t o t he f l ange met al

Cor r osi on Prot ecti on[ 80, 1261 The means of r educi ng corr osi on i ncl ude

1 Use of c or r o s i o n- r e s i s t a ntmetal s and al l oys

2 Prot ecti ve coat i ngs such as pai n t ,el ec t r opl at i ng, e t c

3 Cathodi c protecti on by t he use of a s a c r i f i c i a lmet al hi gher i n t he e l e c t r o p ot e nt i a ls e r i e s

I mper vi ous graphi t e f or handl i ng hydrof l uori c, s u l f u r i c ,and n i t r i ca c i d s has some t emperat ureand concent rati on l i m t s t i s unsui t abl e f or use w t h f r e e bromne, f l u o r i n e ,and i o di ne ,as wel l aschromc a c i dand s ul f ur t r i o x i d e Normal l y, i t sporosi t y makes graphi t e unsui tabl e as a pi pi ngmateri al ; however , vari ous r e s i nsused as i mpr egnant s wi l l produce an i mper vi ous materi al he pi pemanuf actur er shoul d know what corrosi ves ar e t o be handl ed so he can provi de t he proper i mpr egnant

concern here woul d be t he e f f e c t sof hi gh radi ati on on t he organi c r e s i nas wel l as t he graphi t e

he use of l i n e dpi pi ng syst ems f or corrosive surf aces i s rapidl y i ncreasi ng Li ni ngs i ncl ude g la s s ,p l a s t i c s ,el astomers, and vari ous metal s Li ned pi pe syst ems usual l y r e l yon carbon s tee l as amai ns t ru c tu r a lcomponent : ease of l ubri cati on and l ow c os t permt i t suse wi th most l i n i n g sandmanuf actur i ng t echni ques Gl ass- l i ned s tee l pi pe has one of t he broadest r anges of corr osi on r e s i s t a nc e

of al l t s smoot h surf ace i mpr oves product f l ow, but i t has poor i mpact and t hermal shock r e s i s t a n c e,requi ri ng care and handl i ng dur i ng i n s t a l l a t i o nand mai nt enance Ther mal shook r e s i s t a n c ecoul d be aval idconcern where one pl ans t o compl etel y and qui ckl y r emove t he fue l f rom t he pr i mary c i r c u i t ,several t i mes per year

Ther mal and Radi at i on- I nduced xpansi on Temper atur e and radi ati on wi l l cause mos tmateri al s t o expand Thi s wi l l a f f e c tt he choi ce of mater i al s f or core tubes , reactor v es s e l , ando u t - o f - r e a c t o requi pment p i pes ,pumps, heat exchangers f or pri mary, secondary, and t e r t i a r yc i r c u i t s Tabl e gauges t hermal expansi on f or some mater i al s of i n t e r e s t both o and graphi t e l ooka t t r a c t i v e



Core t ubes need t o be f ar enough apart t h a t expansi on does not cause s t r e s s e sby f orci ng t hemt ogether Desi gn f or l ongi t udi nal expansi on w i l lprevent bow ng and/ or breakage of g r a ph i t e

Pr oper l ayout shoul d accommodat e expans i on i n o u t - o f - r e a c t o rpi pi ng Expansi on e f f e c t si n a

pump or heat exchangerar e mor e c r i t i c a l

f ort unat el y r a d i a t i o nl e v e l sthe re ,

f romdel ayed neut rons,are near t h r e emagni t udes bel ow t hat i nt he core

Chemcal Reacti ons i n an M R

Compat i bl e content materi al s are t hose whi ch do not form s t a b l echl ori des Exampl es ar eg r a ph i t e ,i r o n , n i c kel ,and t he r e f r a c t o r ymet al s The chl ori des of t he pure f ue l s a l t are hi ghl y s t a b l e ,r e ac t i n gl i t t l w t h materi al s t h e ycont act However , over t he reactor l i t he core and bl anket s a l t sw i l lmut at e i n t oa vari et y of composi t i ons, beget t i ng addi t i onal chemcal speci es f i s s i o nproduct s andf r e echl ori ne f rom f i s s i o n; other mut ant s t hrough neut ron capt ure ; oxygen cr eepi ng i n t hrough s e al s Fort unatel y, f l u i dsys t ems can process cont i nuousl y whi ch hel ps t o keep t h e se i mpuri t i es l ow

Chem cal r e a ct i o n sbet ween t h e s es a l t mxtures and i ncompati bl e cont ai ner materi al s coul d

Preci pi t at e f i s s i l emat eri al l eadi ng t o c r i t i c a l i t ys a f e t yprobl ems

2 I n t he presence of hi gh t emperat ures, hi gh v e l o c i t i e s ,and hi gh radi at i on f i e l d s ,causecorr osi on l eadi ng t o l eakage and mai nt enance probl ems

React i ons w t h Fi ss i on- Pr oducedMut ant s When urani umf i s s i o n s ,t he UC 3 mol ecul ars t r u c t u r ebreaks up, creati ng t h r e echl ori ne i o n sand t wo f i s s i o nproduct s FP Tabl e 7 [ 9] g i v est heval enci es o f - t h e s eFP i n t h e i rmos t s t a b l es t at e l a r ges t , f r ee,energy of f or mat i on [ 17, 32, 86, 127] atreactor t emper at ures

Tabl e Coef f i ci ent s of t hermal expansi on f or some candi dat e s t ru c tu r a lmateri al s [ 86, 97]

Mat er i al Temp Range ° C Coef f i ci ent 10 6/ ° C

Ext r uded graphi t e al ong t hegrai n 20- 100

10002

agai nst t he grai n 20- 1001000

3

Mo 5C 5

Hast el l oy N 20- 100 11

Fe 25 12

N25 12-13

3 4SS 25 17

Cr ol oy 20- 100 18



The FP w i l l onl y form chl ori des i f t he f r e eent hal py of f or mati on exceeds about 20 k i l o j o u l e spermol e chl ori ne: FP up t o and i ncl udi ngmol ybdenum The gases xenon, krypt on, and probabl y i odi neand br om ne ar e i n er t t o chl ori di zati on; so ar e t hemor e i n er t met al s such as pal l adi um t echneti umr ut heni um r hodi um and probabl y te l l ur i um Based on MSR exper i ence they wi l le i t h erent rai nw t h t he i n er tgases or p l a t eout on met al s u r f a ce s

Thi s sugges t s the product i on of about 80 kg i nsol ubl e metal per Gwt h- year That amount of met aldeposi t i on warr ants seri ous a t t e n t i o nt o prevent r e s t r i c t i o n sand pl uggi ng

Si nce each Pu atom i s s i o n si n t otwo product at oms, t he average val ency shoul d be 3 chl or i dei ons per Pu/ 2FP per Pu = 5 t o mai nt ai n el ec t r o neut r al i t y Chasonov showed that f or PuCl3 t heaverage val ency i s cl ose t o 0 i ndi cat i nga def i ci encyof Cl i ons However , t he r emoval of t her e l a t i v e l y - i n e r tmet al s l i k eRu, Pd, and Te, e i t h er t hrough pl ate-out or de l i ber a t e l yby t he pr ocessi ngsystem can qui ckl y l ower t he aver age val ency Bel ow . 5 Cl i ons ar e i n excess, produci ng cor r osi on

I n s ummar y, t ube pl uggi ng may occur at some l ocat i ons and t ube di ssol ut i onby cor rosi onatothers I n - pi l e t es t i ng t ohi gh bur n-ups i s needed t o study these compet i ng e f f e c t s

Exper i ence on mol t en f l uor i de sys t ems i n di c at e stha t i r r a d i a t i o nand f i s s i o nproduct s do notaccel erate corr osi on McLai n p . 800

Mol ybdenum as a f i s s i o nproduct w t h a y i e l dof 18 out of 200 of al l f i s s i o nproduct s mayr emai n, i n p a r t i n met al l i c f o r m When mol ybdenum s t he s t r u c t u r a lmater i al , t he corr osi onpr obl emsof met al l i c mol ybdenum or i t s al l oysar e s t r on gl yl i nked w t h t he f i s s i o npr oduct behavi or i n t h i smedi um Fi ssi onf r agment MoCl2 w i l lr e a c t w t h UCl3 t o f o r mUCl 4 p l u s Mo Li kew s et he excess

chl or i ne r el eased w i l lr eac t w t h t he strongest r educi ng agent p r e se n t UC3, t o f o r m UCl 4.

The E f f e c tof UCl 4Presence i n t he Cor e Sal t [ 31]. Pure UCI , hi ghl y corrodes cont ai nermet al s , but bot h theory s t abi l i t yof cor r osi onproduct chl ori des and l abor at or y exper i ence show tha t

d i l u t e U Cl f uel at t a cksl i t t l e: al l oys of i r o n n i c k el or refractory met al s such as mol ybdenum r e si s tchl ori de f u el and bl anket s a l t s pr ovi di ngt he UCl3 UCl4 mx cont ai ns no mor e than a f ew per cent

UC4. Al l oyscan a l s oi ncl ude mnor amount s of mor e r e ac t i v emet al s suchas c hr o m u mi f t he d es i g nal l ows f or some sur f ace l eachi ng

Ext r apol ati ngf r o mORN exper i ence w t h f l u o r i d ef u el s a l t sat compar abl e heat r a t i n gsi r r a d i a t i o nshoul d nei t her rel ease chl ori nef r o mt he mel t nor enhance t he attack of t he cont ai nermater i al s

Tabl e 7 Val enci esof t he f i ssi onpr oduct el ement s i n mol t en chl ori des

Val ency l ement s

- 2 Se, Te- 1 I

0 Kr , Xe 1 Rb, Ag, I n Cs 2 Sr Zr Mo, Pd, Cd, Sn, Ba, Sm Eu 3 Y, Tc, Ru, Rh, Sb, La, Ce, Pr Nd, Pi n Gd 5 Nb



andi date Mat er i al s f or an M R

The hi gh f l u x l e v e l si n an M R suggest hi gh r a d i a t i o ndamage However , due t o t he uni que

tube conf i gurati on t he onl y exposed s t r u c t u r ei s the core/ bl anket i nt e r f a ce: t he bl anket s hi el dst hevessel , reduci ng t r a d i a t i o ndose by t h r e emagni t udes

eyond t he hi gh r a d i a t i o nenvi r onment of t he reactor l i e pi pi ng, pumps, and heat exchangers f orthe pr i mary f uel - cool ant These f ace exposure t o hi gh t emperatures, del ayed neutr on i r r a d i a t i o n ,andcorrosi on by s a l t t r ansmut ant i mpuri ti es

Mat er i al s i n t he secondary and p o s s i b l e - t e r t i a r yc i r c u i t sface a much m l der envi r onment

However , t he amount s of materi al s t her e gr eat l ysurpass those i n t he pr i mary c i r c u i t ,therebys e n s i t i z i n gt h e i rc os t: except f or t he hi gh t emperature hel i umcase , one pref ers l ower operat i ngt emperatures so as t o al l owcheaper materi al s The c os t f a c t o r ,however, must a l s obe bal anced w t hfactors of corrosi on, t hermal s t r ess , and avoi dance of secondary- cool ant f reezi ng e s pec i al l yf or a ct i v e

l iqu id metal on the i nt ermedi at e heat exchanger t ube s

Tabl e 8 l i s t st he most prom si ng materi al s f or use w t h t he di f f er e ntf l u i d s Strengthconsi derat i ons di c t at et he t emperature l i m t s Corr osi on t e s t s under M R condi t i ons have general l ynot been carr i ed out yet Mat er i al s whi ch bes t r e s i s t corr osi on by chem cal attack shoul d be thosew t h smal l f r e eenergy of chl ori de f ormat i on Low vapor pressure hi gh boi l i ng and mel t i ng poi nt swi l l al s oal l ow chl ori des whi ch fo rm t o r emai n as protecti ve cover i ngs From avai l abl e i nf ormat i onMo i s a strong candi date

Overvi ew on Metal s H gh ni ckel a l l o y sand r e f r a c t o r ymetal s appear t o be t he onl y metal scompat i bl e w t h fu e l and bl anket s a l t Super i or s t r e n g t hand resi stance t o corr osi on and r a d i a t i o n

embri t t l ement at hi gh t emper atur e recommend mol ybdenum al l oys par t i c ul ar l yTZM f or contact w th

Tabl e 8 Materi al s f or vari ous M R f l u i denvi r onment s

Appr oxi mate Mater i alFlu id Candi date Mat eri al s Temper at ur e L i m t °C

Mol t en Chl ori de S al t S t a i n l e s ss tee l 600Hastel l oy N 7Mol ybdenum or TZM 1000- 1200 ?Gr aphi t e 1500

Hel i um Ni ckel a l l o y s 900- 1000Mol ybdenum or TZM 1000Graphi t e 1500

Lead Fecral l oy or Crol oy 5

Mol ybdenum 1000 ?

Super heated Steam St ai nl es s s t eelor hi gh ni ckel 55al l oy s

Lower Temper atur e I r o na l l o y s 45Steam and wat er



t he c i r c ul at i ngf l u i d

Ther e i s some i ncent i vef or usi ng mol ybdenum al l oys f or al l t he component s i nc l udi ngpumpswhi ch contact t he s a l t However mass i ve mol ybdenum out si de t he core woul d requi repr ecauti onsagai nst i t s external oxi dat i on e . g encl osi ngt he reactor vessel and ot her s e n s i t i v ecomponent s i n a hotbox pur ged w t h an i n e r tor s l i g h t l yr educi ngat mospher e An a l t e r n a t i v et o t h i s woul d be t o usedupl ex m t er i al a pr otect i ve o l a yerel ect r odeposi t edor pl asma spr ayed onto cer t ai n s t e e l s

For t he l e s s severe condi t i onsof t he reactor vessel and t he s a l t ducts returni ngf r o mt he heatexchanger , Hast el l oy- Nor advanced devel opments of t h a t a l l o ymght s u f f i c e However , havi ngdeci ded t o us e mol ybdenum or t he core/ bl anket membr ane a change t o a di ss i ml ar met al el sewher ei n t he s a l t c i r c u i tc oul d c aus egal vani ccor r os i on Al so, ni ckel a l l o y sr e s i s tmol t en l ead a candi dat esecondary cool ant very poor l y c ompar ed w t h mol ybdenum they woul d pr obabl y be subj ect t o a t t a c kwhen t he l ead l eaked through t he heat exchanger i n t ot he s a l t

o Al l oys o o f f e r shi gh t emper at ur e s t r e n g t hgood i r r a d i a t i o nr e s i s t a n c eand hi gh t her malconduct i vi t y pr omsi ng t r a i t sf or a m t er i al i n contact w t h fu e l and bl anket s a l t sa t hi ght emper at ur es However , f abr i cat i onof l i g h tmol ybdenum s ec t i o ns r equi r eswel di ngand heat t r eat ment t h i s t echnol ogyneeds devel opment , but i t al r eady pr oceedi ngf o r ot her appl i cat i ons

Al so, t he hi gh s p e c i f i cc o s t of mol ybdenum s accept abl e onl y on a l i m t e d basi s t he vesselpi pi ng, e tc shoul d use m t e r i a l s whi ch a r e cheaper and mor e e a s i l yf abri cat ed Candi dat es i nc l udeMo/ Fe, Mo/ N and Ti / Zr / Mo TZM a l l o y s W t h Mo/ Fe i ndi cat i onsar e t h a t t he swel l i ngf or Fe hasal r eady peaked a t t he operat i ng t emperat ures, whi l e t h a t f or Mo occurs at much hi gher t emper at ur es

The use of mol ybdenum or t a l l o y smay permt hi gh f u e l s a l t t emper at ur es above 1000°CThi s can reduce f u e l s a l t i nvent ory t hr ough hi gherpower dens i t i esand a l l o wgas turbi ne cycl es and/ orpr ocess heat appl i cat i ons usi ng hel i uma s an i nter medi ate and f i n a lcool ant

o has an appr eci abl e absor pt i oncross sect i on f or neutrons Such r eact i ons al so pr oduces i g n i f i c a n tamoun t s of t ec hnet i um Thi schanges t he nat ur e of t he s t r u c t u r a lmter i al and makes i tradi oact i ve

Previ ous di scussi oni ndi cated o t o be s t r o n g l ycor r osi onr e s i s t a n t The most s i g ni f i ca nt r ea ct i onfrom t he st andpoi nt of cor r o si onshoul d be

UCI , + o - 2 UCl3 MoCl 2

UCl 4 wi l l bea ma j o r c ons t i t u enti n t hebl anke tf r o m t heneutront r a ns mu t a t i o nof ThCl4. F r ee c hl or i def r o mf i s s i o nof U n t he core combi ne w t h UCl3 t o f o r mUCl 4. I t a l s or ea ct s di r e ct l yw t h Mo

o + C1 - MoC 2

Traces of oxygenor wat er w i l lpr oducemol ybdenum oxi de, e . g

MoCl oo Cl

W t h al l of t h e s er e a c t i o nsmechani ca l p r o pe r t i e sw i l lchange

Gr aphi t e Bot h carbon and graphi t e r e s i s tcorr osi onand conduct heat wel l enough t o war r ant



e x i s t i n guses i n heat exchangers and pumps r esi n- bonded graphi t e has f ound w de appl i cati oni nt he chemcal process i ndus t r i es Bot h Amer i ca and France have used graphi t e w t h Li F/ BeF2 mol t ens a l t: McDonnel l - Dougl asmar ket s a h i g h - s t r e n gt h ,woven graphi t e f or t h i s; t he French company PU

s e l l sa product w t h graphi t e connect ed t o heat exchanger mat eri al [27]

The hi gh t her mal conduct i vi t y r es ul t s i nexcel l ent t her mal shock resi st ance S t i l lone must e xe r tcare as carbon and graphi t e ar e weak and b r i t t l ecompar ed w t h met al s

Tensi l estrength vari es bet ween about 5 and 3000 l b / i n 2 and i mpact resi st ance i s ni l Abrasi onresi st ance i s poor H gh t emperat ure s t a b i l i t y s good and they can be used at t emperat ures up t o 4000or 5000°F i f protected f r o moxi dati on ( burni ng) Si l i con- base coat i ngs s i l i c i d e sor s i l i c o ncarbi de)and i r i d iumcoati ngs ar e cl ai med t o gi ve prot ecti on up t o ar ound 2900°F

Based on t he e x i s t i n gexperi ence as a s t r u c t u r a lmat eri al f or mol t en f l uor i det her mal breeders andon peri odi c r epl acement of tubes , we as sumed graphi t e f or t hephysi cs s t u di e shere 2 cm t h i c kf or t he

tube wal l and 4 cm t h i c kf or t he vessel wal l

Heat Exchanger Consi derat i ons As ment i oned above l ow vapor pressure of t he pr i mar y andsecondary fused s a l t s per m t s t h i n- wal l edheat exchangers These ar e hi ghl y ef f i c i ent i nheat t r a n s f e r ,thereby decreasi ng necessary area and f i s s i l evol ume out-of-core However , assumng cl ose p i t c h ,theywi l l requi re devel opment and t e s t i n gt o r e s i s t t he t her mal and v i b r a t i o n a ls t r a i n sover a l ong wor ki ngl i f e

Refractorymet al s a r e a t t r a c t i v eas t hey can ac commodat e hi gh t emperat ures, whi l e s t l laff ordi ngt he good heat t r a n s f e rof a me t a l l i cmat eri al s t r i n gcandi dat e s Mo t does have an appreci abl ecross s ec t i onf or neut r on absorpt i on t h i s a f f e c t sdel ayedneut r on acti vat i on but not neutron economyor r a d i a t i o ndamage t h e r e O g r e a t e rconcern s t he wel di ngand j oi ni ngpropert i es of Mo t s

c o s t ,and t s oxi dati on

Mater i a l s f or t he Core Bl anket I nt er f ace

Fi ndi ng an i n t e r f a c emat eri al tha t can w t hs tand a 10 16 n cm 2 sec f l u xover an acceptabl e peri odof t i me i s i ndeed a chal l enge t s gr e at l yeased by assum ng p er i o di cr epl acement of t he f ew t ube s:an act i on f a r l es s compl i cat ed than t he convent i onal r epl acement of fue l el ement s ; j u s t drai n t he coreand bl anket and uncoupl e t he t ubes out si de t he reactor Thi s i s especial l yf e a s i b l ei f one uses a cheapmat eri al l i k egraphi t e The secti on on Access and Mai nt enance di scusses t h i s further S t i l l t he tubesmay experi ence a cumul at i ve dose of 1023 n cm2 i n j us ta f ew mont hs Al so i r r a d i a t i o nof g r a phi t eproduces stored energy

Mat er i al s f or React or Vessel

The reactor vessel wi l l experi ence

( l ) Low pressure

( 2) Temper at ur e hi gher than t he bl anket s a l t mel t i ng poi nt

3 Radi ati on damage f r o ma 1013 n cm2 s ec- 1 f l u x s ui t a bl e ma t er i a lmust meet thesecondi t i ons; i t shoul d a l s o m ni m z e



1 I nduced r a d i o a c t i v i t yso as t o maxi m ze access

2 Cost

Candi dat es i ncl ude graphi te and pr est r essed concr ete of l ow- acti vati ng composi t i ons

Chem cal S t a b i l i t yof Hal i des

Thi s secti on sur veys t he chemcal s t a b i l i t yof t he hal i des i n t he system t endency t o br eak up andt h e i rcor r osi veness t endency t o chemcal l y attack t he s t r u c t u r a lmat er i al s i n t he pr i mar y c i r c u i tat t het emper ature of concer n

Fi gur e compar es t he s t a b i l i t yof some chl or i de and f l uori de compounds t he l ower t he G t hemor e s t a b l e NaCl and Li F ar e p a r t i c u l a r l ygood I n gener al chl ori des ar e l e ss s t abl ethan f l u o r i d e s

Thi s pattern of decreasi ng s t a b i l i t ywi th h a l i d eatomc number cont i nues t hr ough br omne and i odi ne

The smal l al ues f or MoCl 2 and MoCl 3 i n h i b i tt h e i rf ormat i on, whi ch why Mo apr ef er r ed s t ru c tu r a lmater i al i n a chl or i de system Gr aphi t e a l s or e s i s t schemcal a t t a c k f ormat i on ofCF and CCI , we l l The appreci abl e or hal i des of Fe, Cr , and Ni makes them unsui t abl e ass t r u c t u r a lmater i al i n cont act wi th s a l t

Chl or i des gener al l y di s s ol v ei n H O f l u o r i d e sdo not I nsi de t he mol t en s a l t c i r c u i tt he pr esenceof oxygen or water wi l l pr oduce oxychl or i des OCI whi chcor r ode Out si de t he r e a c to r, water



s o l u b i l i t ymay f a c i l i t a t ecl eanup of l eaks or s p i l l s.

AGf o ro t h e rh a l i d e sar el e s sava i l ab le; t h e yar e g en er a l l yl e s ss t a b l e .

Chemcal Behavi or Hal ogens r e a c tvi gor ousl y w t h t he a l k a l imetal s t o f o r ma very s t a b l ebi nar y compound S a l t sof a l k a l i n eearths a l s oexhi bi t l a r g ef r e eener gy f or f or mati on Pb hal i des ar enot so s t a b l e: ORN [13] f ound PbCl 2 t o r e a c tw t h t he s t r u c t u r a lmateri al s avai l abl e t hen They a l s of ound Zr Cl2 t o cause a snowy p r e c i p i t a t e.

I n addi ti on t o havi ng hi gh mel t i ng p o i n t s ,a l k a l ihal i des conduct e l e c t r i c i t yi n t he mol t en s ta te , andotherw se behave l i k eel ectr oval ent compounds W t h t he except i on of l i t hi umf l u o r i d e ,t hey r e a d i l ydi ssol ve i n wat er .

The I r r adi at i on of Mol ybdenum and I r o n i n a Fast H gh Fl ux Reactor

The hi gh neut r on f l u x i r r a d i a t i o ncauses physi cal and chem cal changes i n s t r u c t u r a lma t e r i a l s.

Mol ybdenum s a m x tu r e of s t a b l ei sotopes . The mos t i mpor t ant by- product of neutr oni r r a d i a t i o ni s t he Tc- 99 beta-emtter w t h t = 2 1 x 105years and bel ongs t o t he f ol l ow ngt r ansmut at i on chai n:

23 )98Mo n ,y ) 99Mo be ta - , t 1 / 2=66h)- 99Tc bet a - , t 2=2. 1 x 1 05 y) n , y )1 00 Tc be t a - , t 1 / 2 =17 s ) 100Ru

For appr oxi mat el y 1000 kg mol ybdenum n t he core i n t he f o r mof cool i ng t u b e s , or about 10, 000mol es, t he Mo 9 gi ves 2300 mol . The i r r a di a t i o n r a t e NMo- 9 9( mol s/ s) = 2 . 3 x 103 x 6 x 1023 x( 10 x 10 27) x 10 16= 1. 2 x 1017atoms . After an i r r a d i a t i o nof 700 hr s a steady s t a t econcent r ati on

of99Moi sr eached = 1. 2 x 10 1

7/ 3 x 10 -

5= 3 x

102 at oms = 0 005mol .

The r a d i o a c t i v i t yof t he 99Tc t1/ 2=2. 1 x 105y=6 2 x 1012s) , a f t e rt h r e eyears i r r a d i a t i o nof 1000 kgof mol ybdenum n t he f a s t reactor c o r e ,= 2x1017atoms/ s x 3 x 3 1X107s/ year ) x 10 13 / 3 .7x11= 3 Ci / t onne of Mo

The di ff usi onr a t e of hydr ogen f r o mt he mol t en f u e l t o t he cool ant and bl anket ( her e a l s oUC -NaCl mus t a l s obe ment i oned .

One can as sume tha t t h i s mel t cont ai ni ng hydr ogen i s s a t u r a t e dso t ha t t he por osi t y of t he wal l( mol ybdenum w i l lpl ay a m nor r o l e. The mos t i mpor t ant f a c t o ri s t he v a r i a t i o ni n t he mechani calpr oper t i es of t he mol ybdenum caused by t he upt ake of hydr ogen.

The pr obl emof mol ybdenum cor r osi on i n chl or i ne cont ai ni ng medi a i s p a r t i c u l a r l ycompl i cat ed byt he numer ous mol ybdenum chl or i des: MoC 2 MoC 3. MoC 4 MoC 5

Enhanced Transmutat i on of 90Sr and7s

For t he reference case t he t r ansmut at i on r a t e sobt ai ned a r e:

9 Sr:t=185yr; t teff= 5

137Cs: t e f f= 8 95 yr ; t b/t e f f 3 . 3



The t o t a l r educti on i n hazard f r o mboth f i s s i o nproducts equal s 13 5

The amount of s t r ont i um 90, t hemost hazar dous nucl i de, i n t he hi gh f l u xbur ner i s about t he sameas t ha t f ound i n t he power reactors a f t e r3 years of oper at i on

owever t he most i mpressi ve r e s ul tcomes f r o mconsi deri ngt he end of t he f i s s i o npower a r e a Where by compar ed t o storage n a t u r a ldecay w t h a combi ned hal f l i f eof 39 years) w t houtt r ansmutat i on, t he t r ansmutat i on case shows t h a t t he amount of nucl i des r emai ni ng wi l l be r educed bya f a c t o rof 1000

I n a hi gh f l u xt r ansmutat i on the reduct i on by a f a c t o r1000 woul dbe achi eved w t h 6 years i nt he l i f e t i meof one reactor generati on

The systemproposed f or t he t r ansmutat i on of 90Sr and Cs, f u l f i l l st he f ol l ow ngc r i t e r i a:

1 The ener gy bal ance i s p o s i t i v e

The hazar dous wast e bal ance i s str ongl y negat i ve That i s t he amount of hazar dousmater i al destroyed great l y exceeds t he amount of f r es hl y pr oduced, e g t r i t i u m 0 3 andt he a c t i v a t i o nproducts of t he s t r u c t u r a lmater i al

3 The r a t e of des t ruct i on( t r ansmutat i on) i s approxi mat el y at l ea s tone order of magni t udegr eat er t han t h a t due t o spont aneous beta decay

4 The per i od i n whi ch a t housand- f ol dr educt i on i n t he hazar d can be achi eved i s t he same ast he l i f e t i meof one r e a c t o r ,t h a t i s , 20 t o 4 yr s

5 The neutron bal ance of t he system i s p o s i t i v e That i s i t permts br eedi ng t o occur al ongw t h t he t r ansmutati on

6 The weakest f e a t u r ei s shown i n t he r e l a t i o ns hi pbet ween t he probabi l i t yof cat ast r ophi crel ease t o t he envi r onment f o r t he t r ansmutat i on operati on, P r a n st ot h ep r o b a b i l i t yofas i m l a revent i n t he case of s t o r a g e ,P s t o r ewher e i t i s desi red t h a t

7 The pr oposed syst em a mol t ensal t f a s t r e a c t o r ,whi l e r a t her exo t i cf r o ma t echnol ogi calp oi n tof vi ew, i s not as f ar r emoved f r o m t he present s t a t e of t echnol ogy as some ot hert r ansmutat i on pr oposal s e g hi gh- fl uxhi gh- energy a c ce l e r a t o r s ,contr ol l ed t hermonucl earr e a c t o r smay be

ccess and Mai ntenance

The goal s f oral l nucl ear power pl a nt si ncl udee f f i c i e n tr e l i a b l e ,and s a f ereactor operati on Thi se n t a i l sadequat e i nspecti on and oppor t uni ty formai nt enance and r e pa i r W t h MSRs one can dr ai n t hef u el ,f l us h t he sys temw th cl ean s a l t , and then repl ace t he whol e reactor vessel or i ndi vi dual heatexchanger u n i t s However , w t h external cool i ng, t he pr i mary c i r c u i temts del ayed neut r ons; t h e s ea c t i v a t ec i r c u i tequi pment and t he secondary c o ol a nt ,i n h i b i t i n gaccess and mai nt enance t h e r e

I n t r i n s i c Rel i abi l i t y



The MSR avoi ds i n t r i c a t emechani cal devi ces i t needs

No compl ex refuel i ng mechani s ms

Few of t he cl ose t ol er ances pr esent i n s ol i d- f ue l l e d r e ac t o r s

3 No mechani cal control devi ces i n t he cor e or bl anket

Thi s i mpl i es t he hi gh system r e l i a b i l i t yof a chemcal or hydr aul i c pl ant pumps , heat exchanger s, andcont ai ni ng materi al s w i l loperat e r e l i a b l yso l ong as t hey do not exceed pr oven l i m t sof cor r osi on,t her mal expansi on, and s a l t vel oci ty

MSR Experi ence

MSR demonst r at ed tha t w t h pr oper desi gn one can mai nt ai n an act i ve f l ui d- f ue lsystem w t hout

undue d i f f i c u l t y Such desi gn shoul d e nt a i l easy r epl acement of pump and heat exchanger or i n - s i t ur epai r s an exampl e, a U- t ube heat exchanger al l ows t he maj or component s t o expand and a l s opermts pl uggi ng any l eaki ng t ubes f r o mt he l es s- a ct i vecool ant c i r c u i ts i de These f e a t u r e sdo c os tsome extra f u e l i nvent ory t hough

Compari son of Pri mary Ci rcui t Conf i gur a t i ons

I n nucl ear r e ac t or s r a di a t i oni n h i b i t saccess t o t he pr i mar y c i r c u i t The l i q u i dnature of M FR

f u e l al l ows t he r emova l of most of t he r a d i a t i o nsour ces dur i ng reactor s hut down

One woul d l i k et o desi gn t he pr i mar y c i r c ui t t oa l l o wr educed power oper ati on whi l e r e p a i r i n gasmal l ex- cor e por t i on of t i n a shi el ded c e l l r-rhen r emoval cf me I t - t u b e c i r c u i tf r o moper ati ngwoul d s t l ll eave ( n - 1 ) / nof t he reactor i n oper ati on Adver sel yt he pr i mar y c i r c u i tmus t l i e Cl ose t ot he cor e s o as t om ni m z e out-of-corefue l i nvent ory

React or Mai ntenance Repl acement Procedure

Upon s hut down t he core f l u i dmay d r a i nor be pumped i n t o s a f egeomet r y t a n k s Operat or s coul dt hen f l u s ht he pr i mar y c i r c u i t s ,f i r s tw t h ( i r r a d i a t e d )bl anket s a l t and t hen w t h f r e s hbl anket mx Thel a t t e rm ght f i r s tcl ean up t l bl anket r egi on i t s e l f Each mx woul d need a s e p a r a t edra i n tank Bot ht anks and l i n e sm ght r equi r e auxi l i a r yheati ng Wat er or steam coul d accompl i sh t he f i n a l cl eanupchl or i des di ssol vee a s i l yi n wat er

W t h a cl ean system oper at ors coul d decoupl e and repl ace t he gr a p hi t et ubes j us t l i k e f uelel ement s, onl y much f a s t e r

No del ay t i me s needed f or r a d i o a c t i v i t yt o di e down

Low r a d i o a c t i v i t ygreat l y eases t he handl i ng pr obl ems

3 Spent t ube s w i l l r equi re no ext ensi ve st orage as f or spent f u e l el ement s t hey shoul d bee a s i l ydi sposed of

Onl y a f ew N=3- 6 tubes are i nvol ved



Core t ubes wi l l probabl y requi re t he mos t f requent r epl acement of al l t he s o l i dreact or component sdue t o t he combi ned e f f e c t sof r a d i a t i o ncorr osi on, and hi gh t emperat ure Frequency of repl acementmght be s iml ar t o t ha tf or LWR and LMF R e f u e l l i n g 6-12 mos Even more f r equent i n t e r v a l scan be t o l e r a t e dw t hout s i g n i f i c a n tpenal t y The c o s t sof r epl acement t ubes w i l l be negl i gi bl e a l s o One woul d l i k e t o remove t he tubes w t hout di st urbi ng t he react or vessel Once i n a g r e a twhi l e, t hereact or vessel or a graphi t e vessel coul d a l s obe r epl aced

React or Shi el di ng

External cool i ng may cause some uni que shi el di ng probl em due t o t he cir cul at i on of del ayedneut ron e m t t e r s Assumng a del ayed neut ron f r a c t i o nof 0 . 003 a t o t a l - t o - c o r evol ume r a t i oof f o u r=3 secondary neut r ons per f i s s i o n a core power densi t y of 10 MWh per l i t e rneut ron mul t i pl i c at i onf act or k i n a 5 - i n pi pe = 2/ 3 a reasonabl e a r b i t r a r yguess , [ Ot 82] c a l c u l t e st h a t an unshi el ded 5 - i npi pe w i l lproduce del ayed neut ron f l uxes of t he order 10 2 10 13 n CM 2 sec nearby

Thi s f l ux l evelcoul d appreci abl y a c t i v a t et he pri mary c i r c u i tenvi ronment , causi ngdel ay anddi f f i cul t y i nmai nt enances Rout i nga l t e r n a t esubchannel s t hrough separat e shi el ded c e l l sout si de t hevessel woul d p a r t l yci r cumvent t he probl em t hen i f one subchannel broke down t he operat or coul ddi vert f l owt o anot her Af t er a s u i t a b l edecay t i me t he broken s ubc i r c u i tcoul d be ent ered and f i xed

The del ayed neut ron radi at i on stem f rom r e l a t i v e l yshort - l i vedemtters ; i t wi l l qui ckl ystop oncereactor operati on does The hi gh gamma r a d i a t i o nf rom f i s s i o nand a c t i v a t i o nproduct s l a s t s muchl onger : i t cont i nues duri ng s hut down Cont i nuous f i s s i o nproduct cl eanup hel ps t o keep t h e s egammaradi at i on l ev el sdown

Radi at i on Sources i n Processi ng Equi pment

To avoi d neut rons f ro mdecay al phas, t he process shoul d avoi d use of l i g h t el ement s, e s p e c i a l l yBe, F, B, Li A] , O, Mg and Na i n decreasi ng order of i mpor t ance

The presence of 2 32U especi al l y i n core s a l t process i ng, w l l a l s oproduce penet rat i ng r a d i a t i o n

Auxi l i ar yPl ant

Power Cycl e Opt i ons

Gener al l y t he pri mary cool ant t r a n s f e r sheat t o

n i nt ermedi at e l i q u i dcool ant whi ch generat es st eam f or a t u r b i n eor t o

2 gas cool ant whi ch passes d i r e c t l yt o hi gh- ef f i ci encygas t u r b i n esand/ or process beatappl i cat i ons

Mel t i ngp oi n t corr osi on, and a c t i v a t i o n by del ayed neut rons c ons t i t u t et he mai n concerns i n t heauxi l i ary pl a n t

I nt ermedi at e Li qui d Cool ant f or St eam Cycl e Li qui d met al s and f used s a l t s because oft h e i rhi gh boi l i ng poi nts and t hermal c onduc t i v i t i esal l owoperat i on at hi gh t emperat ures and l owpressures Thi s promot es e xc e l l e ntheat t r a n s f e rw t hout expensi ve and hazardous hi gh pressure



equi pment Low pressure especi al l y permts use of t h i nheat - exchanger tubes

Resear ch e a r l i e ron Na- gr aphi t e r e a c t o r sand l a t e ron LMFBRs has pr oduced a broad base of Na

t echnol ogy Si m l ar t echnol ogy e x i s t sf or t he l owmel t i ng p e r i t e c t i cNa-K mxture Ei ther one butespeci al l y NaK, avoi ds pr o bl em of cool ant f r eezi ng NASA- Lews has a l s opi oneered t he use of K

wi th a K- vapor t u r b i n e g e t t i n gup t o 65 ef f i ci ency That c yc l ewoul d pr obabl y need mor e studyt hough

Unf ort unatel y a l k a l imetal s r e a c t vi gorousl yw t h both steamand mol t en s a l t mal l l e a kont he hi gh- pr essur e steam s i d ecoul d s pel l di s as t er I f t he a l k a l i l eaked i n t ot he mol t en s a l t r emoval bypr ocessi ng woul d be hard Sodi umwoul d r e a c tw t h UCl3 t o f o r mNaCI and pure U met al ; t he l a t t e rcoul dp l a t eout or other wi se accumul at e

Lead behaves b e t t e rchemcal l y as i t r e a c t sl i t t l w t h e i t h e rs a l t or steam and shoul d not enl argeany l e ak s Lead c o s t s a l ot but t ha t has not di sc our aged t he B r i t i s hf r o mchoosi ng i t t w i l lr equi r e

devel opment of s u i t a b l epumps and components especi al l y i n r egards t o cor ros ion The i n e r t i aas soc i a t ed w t h l e ad shi gh densi t y w i l la l s or equi r e hi gh strength constr ucti on

Lead w i l lneed a u x i l i a r yheat i ng t o prevent f r eezi ng dur i ng l owpower and s t a r t - u pcondi t i ons

The cool er p a r t sof the l ead c i r c u i tcoul d use l ow a l l o ys t e e l sbut r egi ons above 500°C may r equi r eother mter i al s t he superheat er w i l lneed dupl ex t ubi ng as l ead a t t a c k sni ckel - beari ng a l l oy s

Mol t en s a l t scompet e f avor abl ywi th l i q u i dmetal s they e x h i b i tt hermal c on du ct i v i t i e si nt er medi at e t o wat er and t he poor er of t he l i q u i dmetal s Thei r s p e c i f i cheat c ap ac i t i e sp a r a l l e lwat er s Fur t her mor e an i nt er medi ate cool ant of mol t en s a l t shoul d mor e cl osel y mat ch t he pr i mar ys a l t i n physi cal p r o pe r t i e st her eby r educi ng f r eezi ng and t hermal s t r e s spr obl em They cos t f ar l e s sthan l i q u i dmetal s Tabl e 8 shows t ha t a wi de choi ce i n p e r i t e c t i cmel t i ng poi nt s e x i s t samongcandi dat e s a l t mxtures

Consi der abl e experi ence e x i s t si n pumpi ng and gener al use of mol t en s a l t s especi al l y i n s a l t bathsand pet r ol eum r e f i n i n gappl i cati ons whi ch f eatur e constant hi gh t emper at ures and cont i nuous systemoper ati on S a l t swork wel l wi th Hastel l oyN

Tabl e 8 Eutecti c mel t i ng poi nts of some s a l t mxes [1 2 1

Sa l t Mx P

ZrF4 NaF 500NaBF4 408

ThCl 4/ PbCl 2 39592 NaBF4/ 8NaF 3842 ( Li F) / BeF 2 6

ThCl 4 NaCI 360- 370ThCl 4 PbC l 2 Li Cl 325- 335

NaNO2 NaNO3 KNO 142NaAI Cl 4 108

However steam l eakage i n t ot he cool ant s a l t coul d pr oduce l o c a l l yhi gh cor ros ion Processi ngd i f f i c u l t i e swoul d a r i s ei f t he cool ant l eaked i n t ot he f u e l s a l t For t h e s e l a t t e rr easons t he B r i t i s hdeci ded agai nst mol t en s a l t s f or t he secondar y cool ant



Cool ant f or as Cycl e CO or ot her oxi di z i nggas l eaki ng i n t o t he fu e l s a l t woul d r e a c t t of o r mUO That coul d overl oad t he oxi de r emoval secti on of t he s a l t cl eanup pl ant

I n e r thel i umavoi ds t h i s pr obl em He cool i ng s a l s ounder devel opment f o r ot her r e a c t o r sal ongw t h a He gas t ur bi ne

t shoul d work wel l w t h mol ybdenum heat exchanger t ubi ng al t hough t h i s i snot ye t f u l l yendors ed

Bot h France and t he Sovi et Uni on are consi der i ng gaseous al um nous chl ori de t o power t he f i r s ts t a g eof gas t u r b i n es; di ssoci ati ng NO N O g a s t he second stage

Lower t ur bi ne wor ki ngpressure w t h gas s houl d permt mor e component pr ef abr i cat i on Thatshoul d l ower i n s t a l l a t i o nt i mes and save on const r ucti onand i n t e r e s tchar ges Avoi di ngt he steamgener ator and t e r t i a r yc i r c u i ta l s or educes c o s t s t he extent dependi ng upon t he gas cycl e eff i ci ency

Poor heat t r a n s f e rp r op er t i e sof gas penal i ze t he cycl e w t h a l a r g erheat exchanger Thi s means

hi gher out of core f u e l s a l t i nvent ory One must a l s oanal yze t he safety of a pr essur i zed secondar ycool ant

Auxi l i ary Hardware

Pumps Pumps t h a t c i r c u l a t emol t en s a l t sexperi ence unusual me t a l l u r gi c a lchemcal physi caland mechani cal condi t i ons S a l t sexhi bi t t emperat ure dependent physi cal pr oper t i es t t emper at ur esnear 700° they corrode many s t r u c t u r a lmater i al s and d e t e r i o r a t echemcal l y i f exposed t o a i r wat er orwater vapor

ORNL successful l y t e s t e ds i ngl e s t a gecent r i f ugal s a l t pumps i n t he MSR and i n l oops a t 650°Cup t o 16 000 hour s Two s t age sem axi al pumps may requi re b a s i cdevel opment work Bot h pumpdesi gns requi re devel opment and t e s t i n gt o successful l y i ncrease s i z e st o t he r ange needed f or a 1000MWe pl a nt

Bot h pump desi gns s e p a r a t et he hi gh t emper ature pumpi ng el ement s f r o mt he pr i mar y s h a f ts e a land bear i ngs t h i s al l ows t he l a t t e rp a r t s t o operate near ambi ent t emperat ures and t o use convent i onall ubr i c ant s An i ne r tgas buffers t he space bet ween t he hi gh t emper atur e pumped s a l t and t he pri marypump s h a f ts e a l El astomeri c s e a l sand l u b r i c a n t smus t be pr otect ed f r o mexcessi ve gamma heat i ngand r a d i a t i o ndamage

I n i t i a l l ymechani cal pump desi gns avoi ded r ubbi ngp a r t si n t he s a l t s; now pumps w t h j our nalbear i ngs i n t he s a l t have operated successful l y

No d i r e c texper i ence e x i s t sw t h hi gh power conti nuousl y r unni ngl e a dpumps The desi gnpr i nc i p l e swoul d pr obabl y f o l l o wt he sodi umpump desi gn devel oped f or LMFBRs but w t h hi gherpower and strength r equi r ements

Core B anket Seal An e a r l i e rsecti on emphasi zes guardi ng agai nst core f l u i d l e aksmor e t hanbl anket l eaks Therefore t he core tubes shoul d be a s i n g l ee n t i t yt hr oughout t he reactor w t h nopressure s e a l bet ween core and bl anket s a l t

One s o l u t i o nmght be t o r out e t he cor e t ubes through a second t ube or sl eeve whi ch penetr atest he reactor vessel However such a sl eeve w i l l i t s e l fexperi ence hi gh radi ati on damage and requi rer epl acement

t woul d a l s ot her mal i ze neut r ons Thus we p r e f e rt o create a bl anket s e a l on t he core



tube Low bl anket pressure enhances t he f e a s i b i l i t yf or i t One coul d a l s odesi gn a cat cher f or l i m t edbl anket l eakage as p a r t of t he bl anket process i ng st r eam Then, no sea l at al l m ght even wor k

F i l l i n g Dr ai ni ngand ump System

Two tanks bel owt he r e a c t o rvessel serve f or f i l l i n gand dr ai ni ng Each can cont ai n t he whol e s a l ti nvent or y of core or bl anket They provi de f or qui ck dumpi ng of t he cor e and/ or bl anket or f oraccumul at i ng s a l t l eaks f r o m t he reactor vessel Two mor e tanks f uncti on as st andbys and as del aytanks f or s a l t r emoval f or pr ocessi ng, one each f or cor e and bl anket An emer gency cool i ng tankwoul d r emove t he decay heat f r o many tank t hr ough t he same system l i n e sused f or preheat i ng

Mechani cal pumps or gas pr es sur e can t r a n s f e rt he s a l t For i n i t i a lf i l l i n gt he f uel orbl anket s a l twi l lbe br ought t o s i t e i n s o l i df o r m E l e c t r i ci mmer si onheaters or steam c o i l sthat pass bel owt hesurf ace of a s a l t bath mel t t he s a l t under i ne r tgas i n smal l no n c r i t i c albat ches Heat i ng a s o l i dbathof s a l t f r o mt he bottomal one can devel op s u f f i c i e n tpressure t o rupture equi pment or expel t he mol t ens a l t t hrough t he s o l i dsurf ace nce mol t en t he s a l tcan be pumped i n t o t he reactor

The pri mary s a l t c i r c u i t swi l l r equi r e preheat i ng t o about 600°C t he secondar y, l e s s I n someareas i t wi l l be mor e econom c and conveni ent t o heat whol e spaces such as t he reactor vaul t andprocessi ng pl ant; t r a c eheat i ng i s bet t er f o rl onger l engths of pi pewor k as i nsecondar y pi pes t o t hesteamgenerators ubmer ged centr i f ugal pumps c i r c u l a t et he s a l t They ar e of a type whi ch permtsno cont act of t he s a l t w t h t he packi ng gl and The ORNL MSRE encount er ed no p a r t i c u l a rpr obl emsw t h preheat i ng

The MSR uni quel y s e p a r a t e sconcentrates, and s t o r e sp a r t of i t s was t es w t hi n t he pl ant f orneutron economy, s a f e t y and cor r osi on pr ot ecti on of t he reactor Bei ng al r eady i n t he f o r mof aconcent r at ed heat source suggests t he p o s s i b i l i t yof d i s s i p a t i n gt he decay heat by putt i ng i t t o work One use coul d be f or preheat i ng Hel i um or a l ow mel t i ngpoi nt s a l t l i k eFl i be 363°C) coul d be t heheati ng agent An a u x i l i a r yheat er woul d provi de a backup heat source, es pec i a l l ypri or t oaccumul at i ng s uf f i c i e nt f i s si o npr oduct wast e

Over al l Pl ant i ze

Bui l di ngl ayout i n t he B r i t i s hMCFR PU desi gn i s compac t t he reactor vessel and pri mary c i r c u i tar e smal l t he p l a ntr equi r es no el abor ate f u e l handl i ng machi ner y The skewed- t ube conf i gur ati onandtube r epl acement machi ner y here f o r f e i tsome of t h i s compact ness I f i n l i nepyr ochem cal processi ngpr oves pr a c t i c aland econom cal , i t shoul d i t i n t he bui l di ng w t h l i t t l s i z ei ncrease Thi s i ncl udes t heatt endant cont r ol and mai nt enance areas I f f e a si b l e hi gh pressure s torage of f i s s i o ngases woul d a l s o

save much space

Hi s t or y of t he MSFR

Begi nni ngs h o r t l ya f t e rWorl d War I I but ext endi ng i n t o the 70 s s ever a l l a bor a t or i esl ooked atmol t en s a l t f a s t reactor MSFR concepts I nt e r e s tgener al l y f ol l owed t he f or t unes of t he t hermal MSRand so has waned i n r ecent years

Thr oughout t h i s t i me t he i nhe r e n tabsence of cl addi ng i n MSRs has hi nted of a neutron economys u f f i c i e n tf or breedi ng or other uses her mal reactor doesn t br eed e a s i l y; i t r e qu i r e scar eful desi gnand cont i nuous

processi ng t o m n i m z e nonpr oducti ve neutron captures i n f i s si onproducts, core



s t r u c t u r a lmateri al s and control poi sons An MSFR s not so s e n s i t i v e; i t has no moder at or and l t t l

i n t e r n als t r u c t u r e Cl and l i m t e d a l k a l i t y pi c al l yNa ar e t he l i g h t e s tmateri al s pres ent Theref ore t heneut r on spectrumr emai ns f a s t and f i s s i o npr oducts absor b f ar f ewer neut r ons

Numer ous wor ker s have al r eady st udi ed t he MSFR U/ Pu) as a breeder f i s s i o npr oduct bur ner andu l t r a - h i g h ,f a s t - f l u xt es t f aci l i t yw t h ver y har d neutron spectrum

Though not usual l yemphas i zed t he very hard spectrumand good neut r on economy of an MSFRof f er t hepr ospect of u s e f u l l yconsum ng al l a ct i ni deproduct s: sooner or l a t e ral l t he t r a ns a ct i ni de sf i s s i o n I f some capture i n i t i a l l y ,t ha t onl y ge ne r a l l yfurther def or ms t he nucl eus t hereby i ncreasi ngt he probabi l i tyof f i s s i o n

US Act i vi t i es

Goodman et al [ 11]pr oposed a mol t enchl ori def a s t reactor MCFR) i n 1952 Scat char d et al [ 121

r evi ewed t he chem cal pr obl emsi nvol ved I n 1956 Bul mer et al , [ 131desi gned and eval uat ed a 500MWh MCFR, external l ycool ed At tha t t i me t he wor k was s e c r e tand onl y l a t e r dec l ass i f i edChl ori desof sodi um magnes i um ur ani um and pl ut oni ummade up t he f u e l s a l t The bl anket wasdepl et ed ur ani umoxi de cool edby sodi um Thei r r e p o r tcont ai ns numer ous t r a d e s tu d i e s ,some s t l l

usef ul

Bul mer chose chl or i desover f l uori des t o l i m tneut r on moder at i on However he f e l t tha t t hestrong 35 CI n , p r e a c t i o nwoul d requi re enr i chment i n Cl Taube [ 14- 16] of t he I n s t i t u t eofNucl ear Resear ch Warsaw shared t h i s vi ew More r e c ent l ybot h Taube [17] and Fauger as [181havement i oned that f l u o r i d es a l t smay work wel l w t h 33U n a f a s t reactor i n s p i t eof t he ext r a moder at i onThe MSFR work t hen s h i f t e dt o Ar gonne Nat i onal Laboratory ANL)

E S B e t t i s ORNL) f e e l s tha t [ 19 ] ORNL s l ook at t he M FR was very s u p e r f i c i a lsi nce t wasout si de t h e i rt her mal reactor charter They mai nl y c r i t i c i z e dt he hi gh f u e l i nvent or y t i e dup i n t he heatexchanger B e t t i st hought that Taube had a good i dea i n di r e c tcool i ng i n- c o r e ,no f u e lc i r c u l a t i o nw t h boi l i ngHg [201,but that i n s u f f i c i e n tqu ant i t i e sof Hg e x i s t ORNL l ookedunsuccessf ul l yat mol t en l e addi r e c tcool i ng cor r os i onpr oved t o be t he Achi l l esHeel

I n 1967 NL s ummar i zed [21] t he fu e l propert i es and nucl ear per f or manceof f a s t r e a c t o r sf uel edw t h ur ani umand pl ut oni umt r i c h l o r i d e sdi ssol vedi n chl ori desof a l k a l i sand al kal i ne-eart hs I ncl udedwer e t he physi cal and chem cal pr opert i es of t he f u e l ,and t he heat r emoval and neut r oni cs f or onehomogeneous reactor and two i nt ernal l y-cool edr e a c t o r s The opt i mum core vol ume f or 1000 MWe

power pr oved t o be 10 000 l i t e r sf or each t ype Each exhi bi t ed f avor abl ec h a r a c t e r i s t i c sof hi gh

breedi ng r a t i o , l a r g enegat i ve t emper at ur e c o e f f i c i e n t sof r e a c t i v i t y,and l ow f uel -cyc l ecost Howevert he u na t t r a c t i v ec h a r a c t e r i s t i c sof l a r g epl ut oni umi nvent or y l a r g evol ume compl exdesi gn andcont ai ner mat eri al pr obl ems i ndi cat ed t he need f or a si zeabl e pr ogr amt o devel op t he MCFR U/ Pu.

Recent l y L E McNeese [22] offeredt he f o l l ow ngcomments on t he M FR

Resi st anceof Mo t o s a l t corr osi onseems t o depend d i r e c t l yon t he oxi dat i ons t a t e sp r e se n t ,as expressedby t he r edox p ot e n t i a l Thi s cor r esponds t o t he di r e c t i o nsof t he Sw s schem cal research

2 Re gr aphi t e vs Mo as a s t r u c t u r a lma te r i a l: gr aphi t e s a s t e p up i n t echnol ogyr equi r ement s I t s a l s o subj ect t o r a d i a t i o ndamage ORNL st opped t he engi neer i ng on i t



f or MS R

3 Re i n- corevs e x t e r na lcool i ng i n - c o r eo f f e r sl ower i nvent or y SI , but hi gh s t ru c tu r a l

r a d i a t i o ndamage The e x t r ashi el di ngf or out-of-corei s i nconsequent i al Though t heout - of - core (Pu)vers i ono f f e r sa br eedi nggai n of 6 - 0 7 t o counteract t he e x t r ai nvent ory, t he economc meas ur e of i n t e r e s t at l ea s tf or U Pu cycl es) i s appr oxi mat el y SI2BG I n summary external w i l l be e as i e st ,but may be l e s s economc i n t e r m of fue l c o s t s Fi ssi onpr oduct bur ner concept sar e of l i t t l ei nt e r e st: onl y 129Iseparati on has beencont empl at ed

4 The Sw s s mol t en chl ori de f a s t reactor desi gns pr es ume that a stream of about one ppm canbe cont i nuousl ydi r e c t e df or pr oces s i ngand returned For t h i s:

a t he chemstry e x i s t s at l e as t f or f l u o r i n esystem) ;b t he engi neeri nga b i l i t ye x i s t s;c t he smal l - scal e ORNL/ MSBR pl an- 11 was not f i ni s hed; andd scal i ngup has not been done and woul d be a s i g n i f i c a n tundert aki ng- - - much

work t o be done

European Acti vi ty

Pol an d/ Sw t ze r l an d,Led by Meczysl aw Taube Taube f i r s t i n Pol and and l a t e r i nSw tzer l and l ooked at a vari ety of MSR concepts , pr i mari l yon t he pl ut oni umcycl e Pri nci pal s t u d i e swer e on

1 systemof about f our f a s t MCFRs and one MSR burner of f i s s i o nwast e [ 23 ] Theoveral l systemconsumes i t s own f i s s i o nproduct wast es and s t i l lhas a p o s i t i v ebr eedi ng

gai n The bur ner f e a t u r e sa t her mal f l u xt r a p surroundedby f a s t reactor mol t en fue l

Thehi gher t he s p e c i f i cpower (MW1) i n t he system t he l ower t he s t e a d y - s t a t ef i s s i o nproductconcent rat i onbec omes

2 Opt i mzat i on of t he br eedi ng r a t i o f or an MCFR(U/Pu), t h e o r e t i c a l l yachi evi ngl 6 1 8[24]

The 10 power densi ty as sumed by Dr Taube f ar exceeds t he 7 80kW 1 t echnol ogyof ORNL Thus, l i t t l edi r e c texper i ence appl i es S t i l lL E MNeese ( ORNL) was unabl e t oi mmedi at el y foresee any i n t r i n s i cd i f f i c u l t yw t h 10 [22]

Present l y, t he Sw s s wor k has s t opped, as t he e l e c t o r a t epushes t he l aboratoryfrom eactorresearch t owar ds general energy research and devel opment

Fr ance I n France, Comm Ener g At om que (CEA) and E l e c t r i c i t ede France ( EdF) sponsoreddevel opment of t he MS R as backup t o t he Super phoeni xbreeder EdF emphasi zed l ower power s f ornea r- t e rmf e a s i b i l i t y Thei r l ong- t e r mi n t e r e s t si ncl udedd i r e c t - c o nt a c ti n- cordmol t en- l eadcool i ng CE pur sued hi gher t emper at ur es f or l ong- termappl i cat i on Thei r near- t e r mi nt e r es t scentered onexper i ment al corr osi ons t u d i e s

Fontenay- aux- Roses(CEA) and Pechi neyUgi ne Kuhl man (PUK) studi ed severa lhi gh t emperat ureMSR concept s [ 18, 25, 26], a Th/ 2 U cycl e i n f as t and t her mal f l u o r i d e - s a l tr e a c t o r sand an MCFR( U/ Pu) The MCFR desi gn f e a t u r e si n- corecool i ng anda 7 62 m c y l i n d r i c a lcore surr ounded by a

30 mbl anket

Tabl e 9 i nt er compares t he mai n f a s t and t her mal MSR concepts of t he French



A CEA/ PUK subcompany, SERS, and Car bonne- Lorr ai ne [271carr i ed out experi ment al s t u di e si n

1974- 1976 i ncl udi ng

1 Test s of t he mechani cal per f or mance of t he mat er i al s under t emperatur e andr a d i a t i o n

2 Cor r osi on t e s t s i n sal tat hi gh t emper atur e3 Operat i on cf l oops at hi gh t emperature : one f or i sot her mal hydrodynamc s tu d i e s a

non- i sother mal one w t h smal l f l owf or heat exchange s tu d i e s and a t h i r dnon- i sothermalone f or cor r osi on

I n 1977, i f t he above r e sul t swer e p o s i t i v e they wer e t o deci de on a devel opment pr ogr am whoseobj ect woul d be t he const r ucti on of a pr ot otype of 25 5 MWh

The Amer i can and Fr ench at omc or gani zat i ons wer e al s o seeki ng t o agree on t he f i e l d sofpr epar at i on f or a 2 MWe MSBR demo p l a nt They wer e t o deci de i n 1979 on t he const ructi on oft h i s r e a c t o r dependi ng on t he pr ogress w t h hi gh t emper at ur e r e a c t o r sand success of t he French

Super phoeni x 1200 MWe Li qui d Met al Br eeder Reactor LMFBR

Engl and B r i t i s hworker s st udi ed MSRs i n 1964 and 1965 The MSFR i n t e r e st e dthem t he mostand they f e l t that such a st udy woul d compl ement t he US MSBR pr ogr am A prel i mnary study of af a s t syst em usi ng t he 233U/ Pucycl e and f l u o r i d es a l t s di d not l ook encour agi ng, so they r ef ocused ona 233U Pucycl e and chl ori de s a l t s Work on s al t chemstry began i n 1965 ; i n 1970- 1972 t he pr ogr am

ext ended t o i ncl ude ot her mat eri al s aspect s

Tabl e 9 Compar i son of French MSR concept s

CHARACTERI STI C Fast Reactor Ther mal Reactor

Power Mw : Ther malEl e ct r i c al

20501000

2251000

Core s p e c i f i cpower w cm 255 22

Eff i ci ency 49 44

F ue l mol 15 PuCl3 85 NaCl 71 7 Li F, 16 BeF 12 ThF4, 3 UF 4

F e r t i l ema t e r i a l mol 65 238UCl3, 35 NaCI 71 7 Li F, 16 BeF12 ThF 3 UF 4

Secondar y cool ant Al Cl3 NaBF 4

Worki ng f l u i d Di ssoci at i ng NO Gas Steam

Core fue l v el oc i t ym s 2 2 5

Neut r on spect r um 01 Kev t o 10 Mev Ther mal

Moderat or None Gr aphi t e

S t r u c t u r a lmater i al : reactor and t ubes Mol ybdenum Al l oy Ni ckel orI ron Added

Hastel l oy- N



Wor ker s at Harwel l and Wnf r i th exam ned t h r ee va r i a nt sof a 2500 MW M FR 238U/ Pu)( 23- 31] : i n- core di r e ct cool i ng by mol t en l ead drops, i n- core cool i ng by bl anket s a t passi ng t hroughMo t u b e s , and e x t e r n a lcool i ng

The d i r ec tscheme encount ered t oo many pr obl ems The i n- core cool i ng concept appeared t owarrant f urt her study but the fu e l i nvent ory di d not appear t o be a s l ow as f i r s t t hought ; a l s ot he hi ghv e l o c i t i e sand hi gh pumpi ng pressures pr esented seri ous desi gn pr obl ems The corr osi on l i m t sandst rength of mol ybdenum or i t s a l l o y sa t react or t emperat ures represent ed a l a r g eunknown

Wt h ext ernal cool i ng, a t f i r s t t he fu e l i nvent ory i n t he react or c i r c u i twas t o hi gh However ,c ompac t l ayout s and hi gher bu t s t i l lachi evabl e heat exchanger vol umet r i c r a t i n g sreduced i t t o w t h i nreason The neut ron f l u xwas 3 x 10 1 n cm s i n t he react or and 3 x 1 i n t he heat exchanger

Sovi et Uni on Very l i t t l ei s known about Sovi et Uni on engi neer i ng s t u d i e s However , extensi ves a l t t hermodynam c and physi cal propert y s t u d i e ssuggest a much l a r g ersupport i ng research programt han i n t he West ern wor l d USSR revi ew book on Li qui d- sal t Nucl ear React ors regards MSRs a sreactors of f u t u r ew t h c ompac t and promsi ng fu e l cycl es They concl ude t h a t t he devel opment alf ocus must be on t he e xt e r n a lfu e l c y c l e ,ergo t he USSR a t t e n t i o nt o s a l t propert i es

Summary MSR S t a t e - o f - t h e - A r t

Both t he 2 MWh RE and t he 8 MWh MSR demonst rat ed ext ended successf ul MSR

perf ormance but under condi t i ons l e s s str enuous t han t hose consi dered f or a 1000 MW or M FR

The quest i on r emai ns : w i l l a c i r c u l a t i n g - f u e lsyst emhol d t oget her l ong enough t o be p r a c t i c a l ?Mores p e c i f i c a l l y ,how w i l l t he candi dat e cont ai ner materi al s Mo a l l o y s ,gr a p hi t e, o rcomposi t es w t h t hese hol d up a t hi gh t emperat ure t o corr osi on by t he vari et y of mut ant s and oxi dat i on s t a t e swhi ch hi gh

burnup produces? The answert o

such quest i onswi l l

come f rom i n - p i l ecorr osi ont e s t i n g

The Frenchhave an ongoi ng experi ment al program i n such engi neeri ng s t u d i es ,but i t may be propri et ary

Much wor k needs t o be done i n devel opi ng and scal i ng up t he processi ng system

Wth e x t e r n a lcool i ng most of t he fu e l c i r c u l a t e sout si de t he core Thi s t h r e a t e n st he react ors t a b i l i t y I nvent ory reducti on requi res compac t l ayouts and hi gh heat exchanger ef f i ci ency



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18 Fauger as, P e t al Mol t en Sa l t Reactors f or H gh Temper at ur es, Tr ans APS, 20 : 703- 704,Apri l 1975

19 B e t t i s ,E S Pri vate communi cat i on, 13 November 1975

20 Taube, e t al New Boi l i ngSa l t F a s t Br eeder React or Concept s, Nucl ear Engi neeri ngand Desi gn, 5 109- 112, 1967

21 Nel son, P e t al , Fuel Propert i es and Nucl ear Per f or manceof F a s t Reactors Fuel ed w t hMol t en Chl ori des, Nucl ear Appl i cat i ons, 3: 540- 547, Sept ember 1967

22 McNeese , L E ORNL) Private communi cat i on, Apr i l 1977

23 Taube, E H Ott ew tt e, and J Li gou A Hi gh- Fl uxFast Mol t en Sa l t React or f or t heTr ansmut at i on of Cassi um 137 and an St r ont i um 90, Sw ss Feder al I n s t i t u t ef or React orResearch, Wuerenl i ngen, Sw t zerl and, EI R- 259, Sept ember 1975

24 Taube, Ver y H gh Br eedi ng Rat i o i n t he Mol t en Chl ori deFast Power React or w t hExt er nal Cool i ng, Sw ss Feder al I n s t i t u t ef or React or Research, Wuerenl i ngen,Sw t zer l and, I n t e r n a lReport) TMHL- 261, J u l y 1975

25 Gr enon, and J Gei st Mol t enSa l t React ors, Oak Ri dge Nat i onal Laboratory,Tennessee, ORNL- TR- 2508 Transl ated by F Kertesz f r o mEner g Nucl P a r i s ) ,13( 2) :

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26 Gr enon, and J J Gei st Mol t enSa l t Reactor , Rev Fr Ener g 25(263) : 477- 487, May1974 i n Fr ench)

27 Taube, Private communi cat i on, August 1975

28 Di l l on, I G Revi ewof t he Chem str y Mol t en Sa l t Reactors and t he equi l i br i umBet weenMol ten Meta l andS a l t s , Dept de Geni e Radi oacti f , Centre d Etudes Ncl eai r es deFont eney- aux- Roses, CEA-CCNF-2690, CONF- 730482- 1,1973

29 Smth, J et al An Assessment of a 2500 MWe) Mol t en Chl ori deSa l t Fast Reactor,

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3 Ral ph, J Di r ect Contact Heat Transf er i n a Mol t en Sa l t Fast Breeder Reactor, AnExper i mental Study Usi ng Anal ogue F l u i ds , React or Heat Transfer, edi ted by Dal l eDonne, Karl sr uhe, Ger many, 1973, paper no 23, pp 704- 727

31 Har der, B R G Long, and P St enaway Compati bi l i t yand Pr ocessi ng Pr obl ems i nUse of Mol t en UCl 3- Al kal iChl ori desMxture a s React or Fuel s, Symposi um onRepr ocessi ng of Nucl ear Fuel s, I owa S t a t eUni ver si t y, Ames, I owa, 25- 27August 1969,( Nucl ear Metal l ur gy, Vol ume 1 5 ) , e di t e dby P Chi ot t i ,CONF690801, 1969, pp 405- 432



3 The D l emma Over Spent F ue l Who s t o Do What w t h How Much . . And When TheEner gy Dai l y, February 1979, pp . 4- 6

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34 Saf e Handl i ng of Radi onucl i des, Safety Seri es No. 1, Code of Pr ac t i c e sponsored by t heI AEA and t he Worl d Heal t h Organi zat i on) I AEA Vi enna, 1973.

35 Angel o, J . J r. and R G Post . Nucl ear Fuel Cycl e and t he I sotopi c Composi t i ons,Nucl ear Technol ogy, 24 3) : 323- 330, December 1974

36 . Wol f e, R and R Ramey The Tr ansurani um Cont am nat ed Waste Research andDevel opment ProgramW thi n t he Ener gy Research and Devel opment Adm ni str at i on ERDA) , Trans . AN3 21 : 246, J une 1975

37 O l i v i e rJ . P The Management of Fi s si onProducts and Long- Li ved Al pha Wast es,Advances i n Nucl ear Sci ence and Technol ogy Vol . 8 pp . 141- 172, 1975 .

38 Gera, F and D C J acobs Consi derat i ons i n t he Long- Term Management of H gh LevelActi ve Wastes, Oak- Ri dge Nat i onal Laboratory, Tennessee, ORNL- 4762 February 1972

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45 US E Di vi si onof Waste Management Transport ati on . Hi gh- Level Radi oacti ve Was t eManagement Al t e r n a t i v es Was hi ngt on, D C May 1974

46 Wl d, H Radi oact i ve I nvent are and deren z e i t l i c h e rVer l auf nach Abschal t en desReakt ors , I n s t i t u tf u e r Angewandt e Syst em echni k and Reaktor physi k,Kem ors chungs zent nm Karl sr uhe, Kf K- 1797, 1974 .

47 McKenzi e, D S et al Di sposal of Transurani c Sol i d Was t e Usi ng At om cs I n t er n a t i o na l



Mol t en S al t Combust i on Pr ocess Atomcs I n t er n at i o na l ,Canoga Park Cal i f o r n i a ,AI - ERDA- 13151 May 1975

48 Bower s E U et al , Wast e Management Speci al Studi es Pr ogress Repor t December 1974 J anuar y 1975 A t l a n t i cRi chl and Hanf or d Co Ri chl and Washi ngton ARH- LD- 107 DFebr uar y 1975

49 Aug Ki s t Paen Quant i t i es of Act i ni des i n Nucl ear Reactor Fuel Cycl es Lawr enceBerkel ey Laborat or y Cal i f or ni a LBL- 3682 Apri l 1975

50 Taube Pl ut oni um - Gener al Sur vey Ver l ag Cheme GmbH Wei nhei mBer gst r

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51 Ott ew tt e E H Tr ansur ani um Cr oss Sect i ons Whi ch I nf l uence FBR Economcs SecondConf er ence on Neut r on Cr oss Sect i on Technol ogy Washi ngton D C March 1968 U S

Dept of Commerce N S Speci al Publ i cati on299 Vol ume 1, pp 415- 425

5 Mol kenhauer C The Cont r ol l ed Ther monucl ear React or as a Fi ssi on Pr oduct Bur nerBat t el l e Pac i f i cNor t hwest Labor ator i es Ri chl and Washi ngton BNWL- SA- 4232 1972

53 Gor e F and B R Leonar d Tr ansmut at i on i n Quant i t y of 1 7Cs i n a Cont r ol l edTher monucl ear Reactor Nucl ear Sci ence and Engi neer i ng 53 3) : 319- 323 November1974

54 Wol kenhauer C B K Leonard and B F Gor e Tr ansmut at i on of Hi gh- LevelRadi oacti ve Wast e w t h a CTR Batel l e Pack Nor t hwest Labor ator i es Ri chl andWashi ngton BNWL- 1772 Sept ember 1973

55 Vogel sang H F et al , Tr ansmut ati ons Radi oact i vi t y i n D- T Tokamak Fusi on React orNucl ear Technol ogy 3) : 379-391 J une 1974

56 Hennel l y E J Nucl ear Dat a f or Acti ni de Recycl e Nucl ear Cr oss Sect i ons andTechnol ogy N3S Speci al Publ i cati on4 5 Vol ume Washi ngton DC March 1975 R

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57 Benj amn R et al A Consistent Set of Transpl ut oni um Mul t i gr oup Cr oss Sec t i o ns ,Nucl ear Cr oss Sect i ons and Technol ogy NBS Speci al Publ i cat i on 425 Vol ume I

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58 Cr of f G Par amet r i c Studi es Concer ni ng Acti ni de Tr ansmut at i on i n Power React orsTr ans ANS 22 : 345 San Fr anci sco November 1975

59 Beaman S L Acti ni de Recycl e i n LMFBRs as aWast e Management Al t e r na t i v e, Tr ansANS 22 : 346- 347 San Franci sco November 1975

60 Br een R J El i m nat i on of Ac t i ni des w t h LMF R Recycl e Tr ans ANS 21 : 262 NewOr l eans J une 1975

61 Hegedues F and S Chakr abor t y Cal cul ati on of t he Bur nup of Cs by 80 MeV

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62 Gr egor y, V and Stei nberg, A Nucl ear Transf ormati on Systemf or Di sposal ofLong- Li vedFiss i onPr oduct Wast e, Br ookhaven Nati onal Labor ator y, New York,BNL- 8558 November 1967

63 Stei nber g, et al Neut r on Bur ni ngof Long- Li vedFi ssi onProduct s f or WasteD sposal , Br ookhaven Nat i onal Labor at or y, BNL- 8558, BNL 8558 New York, Sept ember1964

64 Cl ai bor ne, H Neut r on- I nducedTransmut at i on of Hi gh- Level Radi oact i ve Wast e, OakRi dge Nat i onal Labor at or y, Tennessee, ORNL- TN- 3964, December 1972

65 G l i nsky, Vi ctor Nucl ear Ener gy and Nucl ear P r o l i f e r a t i o n ,Nucl ear Mat eri al sManagement 6 4) : 43- 46, Wnter 1977- 1978

66 G l i nsky, Vi ct or Pl ut oni um P r o l i f e r a t i o nand t he Pr i ce of Money, U S Nucl earRegul ator y Com ssi on News Rel ease, S- 78- 8, 1978

67 Topi cal Meet i ngon Anal yt i cal Met hods f or Saf eguar d and Account abi l i t yMeasur ement onSpeci al Nucl ear Mat er i al , W l l i amsbur g, Vi r g i n i a ,May 15-17, 1978

68 Wye, Non- Prol i f erati on: Long-Term S t r a t e g y, For ei gn A f f a i r s ,56 : 601- 23, Apri l1978

69 S t a r r , The Separ at i on of Nucl ear Power From Nucl ear P r o l i f e r a t i o n ,Ener gyTechnol ogy V Chal l enges t o Technol ogy, Proceedi ngs of t he F i f t hEner gy Technol ogyConference, Februar y27 March 1, 1978, Washi ngt on, D edi t ed by R F Hi l l ,Gover nment I n s t i t u t e sI nc Washi ngt on, Apri l 1978, pp 103- 110

70 Nori , Kazuhi sa Possi bl e I mpact on J apan of t he Expect ed New U S Nucl ear P o l i c y ,AI F I NFO No 105, Apri l 1977

71 S t a r r , Nucl ear Power and Weapons P r o l i f e r a t i o n The Thi n Li nk, Proceedi ngs of t heAmer i can Power Conf erence, Chi cago, I l l i n o i s ,Apr i l 18-20, 1977, I l l i n o i sI n s t i t u t eofTechnol ogy, Chi cago, 1977, 39 : 26- 33

72 E D vi si onof Reactor Devel opment and Technol ogy The Use of Thori um i n Nucl ear

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73 Amal di , E The Pr oducti on and Sl ow ng Down of Neut rons, Encycl opedi a of Physi cs,Vol 336, Par t2, Neut r ons and Rel ated Gamma Ray Pr obl ems, Edi t ed by S Fl uegge,Spri nger Verl ag, Berl i n, 1959

74 Leyse, C (EG G I daho, I nc. pri vat e communi cat i on, 1977

75 Li gou, J Mol t en Chl ori des Fast Br eeder React or, Reactor Physi cs Cal cul at i ons, Sw s sFeder al I n s t i t u t ef or React or Research, Wuer enl i ngen, Sw t zerl and, EI R 229, November1972



76 . Br ugger, R N We Need More I nt enseTher mal - Neut r on Beam , Physi cs Today, 21 ( 12):23-30, December 1968

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78 . Lane, J Test - React or Per spect i ves, React or and Fuel - Processi ngTechnol ogy, 12 l ):

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79 Taube, and J Li gou. Mol t en Pl ut oni umChl or i des Fast Br eeder React or Cool edbyMol t en Urani um Chl ori de, Annal s of Nucl ear Sci enceand Engi neeri ng, 1: 277- 281, 1974

8 Font ana, G and N D Gr eene, Cor r osi onEngi neer i ng Second Edi t i on ,McGraw Hi l l ,New York, 1978,

81 . Gl ass t one, S and Sesonske, Nucl ear React or Engi neer i ng D Van Nost r and, Pri ncet on,1963

8 Taube, and J Li gou Mol t en Chl or i des Fas t Breeder React or , Probl em andP o s s i b i l i t i e s ,Sw ss Federal I n s t i t u t ef or React or Resear ch, Wuer enl i ngen, Sw t zerl and, EI R 215, J une, 1972

83 . Desyat ni k, V N S F Kat yshev, and S P Ras popi n . Physi cochemcal Pr oper t i es of Mel t sCompr i s i ngM xt ures of Urani um Tetr achl or i de w t h t he Chl or i des of Al kal i Mel t al s,Sovi et J our nal of At om c Energy, 4 2) 108- 112, February 1977

84 . Ki nosz, D L and E Haupi n . El e ct r i c alConduct i vi t yand Densi t y of Chl or i de Mel t s,Proc of t he I n t e r n at i o na lSymposi um on Mol t enSal t s ,The El ectr ochemcal S oc i e t y,I nc.

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85 J anz, G J Mol t en Sal t sHandbook, Academ c Press , New York, 1967 .

86 Lynch, T Edi t or. Handbook of Mat eri al s Sci ence Vol . I Gener al P r o pe r t i e s , R

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87 J a nz ,G J . F Dampi er , G R Lakshi m nar ayanam P K Lorenz, and R P TTompki ns Mol t en Sal t s Vol ume El e ct r i c alConduct ance Densi t y, and Vi scosi t y

Dat a, Nat i onal St andar d Ref erence Dat a Seri es Nat i onal Bur eau of St andards 15 ,Oct ober , 1968

88 Desyat ni k, V N S P Raspopi n, and K Tri f onov Vi scosi t yof Thori um ( I V)Chl or i de Magnesi um Chl or i de Syst emMel t s, I z v e s t i y aVysshi khUchebnvkh Zavedeni i ,Khi mya i Khi m cheskaya Teknol ogi ya19 3) 351- 354, 1976

89 Perry, Robert H and Ceci l H Chi l t on Chem cal Engi neer s Handbook, F i f t hEdi t i on ,McGraw Hi l l ,New Yor k, 1973, pp . 3- 236

9 Ti pt on, J r. C R Edi t or, React or Handbook, Vol ume I Mat eri al s, Second Edi t i onsI n t e r s c i e n ce ,New York, 1960



91 . By s t r a i ,G P and V N Desyat ni k. Ther mal Conduct i vi t y of Al kal i Met al Chl ori des,Tepl of i zi cheski e I ssl edovani vaZhi dkostei , 1975, pp 34- 8

92 . By s t r a i ,G P V N Desyat ni k, and V Zl okazov Ther mal Conducti vi t i es of Al kal i ne Earth Chl ori des, Tepl of i zi kaVysoki khTemperat ur e, 13 3): 665- 666, May J une, 1975

93 . Sl adkov, I. B and T G Koti na The Ther mal Conducti vi t i es and Ther mal D i f f u s i v i t i e sofCert ai n Group I V and V El ement Hal i des i n t he Li qui d S t a t e , Zhur nal Fi zi cheskoiKhi mi , 48 1878, 1974.

94 By s t r a i ,G P VN Desyam k, and V Zl okazov. The Ther mal Conducti vi ti esofFused M xtures of Urani um Tetr achl or i de wi th Rubi di um and Caesi um Chl ori des, Russi anJ our nal of Physi cal Chemstry, 50 2): 208- 209, 1976

95 Ganbi l l , R Fused S al t Ther mal Conducti vi t y, Chem cal Engi neer i ng, 66 ( 16)

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96 . Perry, Robert H and Ceci l H Chi l ton Chem cal Engi neer s Handbook, F i f t hEdi t i o n,McGraw H i l l ,1973, p 3- 242.

97 . Weast , Robert C and Mel vi nJ . Astl e. CRC Handbook of Chemstry and Physi cs, CRCPress, Boca Raton, F l o r i da ,1981 .

98 . Bondar enko I. I .Group Const ant s f or Nucl ear React or Cal cul at i ons, Consul t ant s Bur eau,New York, 1964

99 Mapl es, C G Got h, and J Cer ny Nucl ear Reacti on Q Val ues, Nucl ear Dat a, 5 ) , ecember 1966

100 Desyat ni k, V N S P Raspopi n, and K I. Tri f onov Cal cul at i onof t he Li qui dus Li nesf or Bi nary Syst ems of Urani um Tet rachl ori de wi th Al kal i Met al Chl ori des Usi ng aStructured Model , Russi anJ our nal of Physi cal Chemstry, 48 : 776, 1974.

101 Desyat ni k, V N I F Ni chkov, P T Porodnov, S P Raspopi n, and V Ski ba. F u s i b i l i t yD agram of ThCl 4 UCl 3and PuCl3- UCl3, I zvesti vaVysshi kh Uchebnykh,Tsvet naya Metal l urgi ya, 13 1) : 101- 103, 1970

102. Desyat ni k, V N and S P Raspopi n I nt e r a ct i onof Urani um ( I V) and Thori um I V)

Chl ori des wi th Sodi um and Pot assi umChl ori des ( The NaCl - ThCl 4- UCI 4andKCl-ThCl4-UCI4Systems ,ussian ournalofnorganic hemistry2 5:780 781 1975

103 Gor bunov, L V V N Desyam k, S P Haspopi n, and K I Tri f onov The I nteracti on ofThori um Tetr achl or i de wi th Al kal i ne Ear t hMet al Chl ori des, Russi an J our nal of I norgani cChemstry, 19 11 ): 1692- 1693, 1974.

104 Desyat ni k, VN The Lead Di chl ori de- Urani um Tet rachl ori de- Thori umTet rachl ori deSystem Russi an J our nal of I norgani c Chemstry, 21 (11) 3166- 3167, 1976

105 Desyat ni k, V N N Vokhmyakov NN Kurbator, and S P Raspopi n PhaseDi agr amof t he Syst emLi Cl UCI , ThCl 4, I zvesti ya Vysshi kh Uchebnykh Zavedeni i



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1 6 Desyat ni k V N NN Kurbator and S P Paspopi n F u s i b i l i t yDi agr amof t he System

ThCI

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107 . Desyat ni k V N Yu T Mel yni kov S . P Paspopi n and I . F N chkov F u s i b i l i t yD agram of t he Syst em PbCI22- ThCI 4 I z v e s t i y aVysshi kh Uchebnykh Zavedeni iTsvetnava Metal l ur gi a 12 3): 99- 100 1969

108 Oymada Ryozo Phase Di agr ams of ThCI Syst ems Cont ai ni ng NaCl KCl and Li CI andt he Li m t at i on of t he Congr uent l y Mel t i ng Compounds For mati on Denki Kagaku 39 l ):2 -5 , 1971 .

109. Vdovenko V Ya Ger shanovi ch and I G Sugl obova Tennogr aphi schesko i

Rent genogr aphi schneskoe I ssl edovani i e Bi nar ni sch Syst em ThCl 4- Li CI i ThCl - NaClRadi okhi m ya 16 6) 886- 889; 1974 .

11 Desyat ni k V N V Dubi ni n F N chkov and S P Raspopi n The F u s i b i l i t yD agram of t he KCl - ThCl System I zvesti ya Vysshi kh Uchebnykh Zavedeni i TsvetnayaMetal l urgyi ya 9, 4): 82-83 1966

111 Kor shanov B G V I . I onov R Bakl ashova and V V Kokor ev. I n v e s t i g a t i o nof t heI nteracti on of ThCl wi th t he Chl ori des of Mg Ca Ce Al , Fe Nb Ta and t he Oxychl or i deof Nb i n Mel ts I zv. Vysshi kh Uchebn Zavedeni i Tsvetn Met . 4 6) 114- 118 1960Transl ated by E E Conr ad I S- TRANS- 56 Ames Laboratory.

112 . J anz G J . R P T Tomki ns C A l en J . R Downey J r. GL Gardner U Krebs andS K Si nger Mol t en S a l t s Vol ume 4 , Pa r t 2, Chl ori des and M xtures E l e c t r i c a lConduct ance Densi t y Vi scosi t y and Sur f ace Tensi on Data J Physi cal and ChemcalRef erence Dat a 4 4 ): 871- 1178 1975

113 Vokhmyakov N VN Desyat ni k N N Kurbator and S P Raspopi n Fus i b i l i t yD agram of t he System Li Cl UCl3 ThCl I zvesti ya Vvsshi kh Uchebnykh Zavedeni iTsvetnaya Met al l urgi ya 16 6) 86- 87 1973

114 Desyat ni k V N Yu T Mel yni kov and I I Tr i f onov. Tr oynaya Syst ema MgCl UCl3

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115 . Desyat ni k V N Yu T Mel yni kov S P Raspopi n and V I Suschko Ter nary Sys t emsCont ai ni ng UCl3 and UCl wi th Chl ori des of Na K and Ca Atomnaya Ener gi ya 31 6) :631- 633 December 1971

116 Desyat mk V N Yu T Mel yni kov S P Raspopi n and I l Tr i f onov. Mel t i ng Poi ntDi agr ams of Ter nar y Sys t ems Cont ai ni ng NgCl CaCl UCl3 and UCl AtomnavaEner gi ya 33 6) : 994- 995 December 1972 .

117 Desyat ni k V N B V Dubi ni n Yu T Mel yni kov and S P Raspopi n I n t e r a c t i o nofUCl3 w i t hAl k al i ne Ear t h Met al Chl or i des ,ZhurnalNeorgani cheskoiKhi m i ,20 4):



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118 Thoma R E et al Sa l tSyst ems f or Appl i cat i oni n Advanced Reactor Technol ogyReactor Chemstry Di vi s i onAnnual Progress Repor t f or Peri od Endi ng

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119 Thoma R E Phase Di agr ams of Nucl ear Reactor Materi al s Oak Ri dge Nati onalLaboratory Tennessee ORNL- 2548 November 1959

120 Desyatni k V N Yu I zmodenov Yu T Mel ni kov F Ni chov and S P Raspopi n

F u s i b i l i t yDi agr ams of Syst ems Based on Magnesi um and Urani um Chl ori des Sovi etJ our nal of Atomc Energy 26 : 634- 635 1969

121 S t e r l i nYa and V V Artamonov Phase Di agr ams of t he Syst ems UCl4- PbCl2 UCI -UC and UCI 4- MgCl2 Sovi et J ournal of Atomc Energy 22 589-593 1967

122 J anz G J G L Gardner Ur sul a Krebs and R P T Tomi ns Mol t en S a l t s Vol um 4,Part Fl uori des and Mi xt ur es E l e c t r i c a lConduct ance Densi t y Vi scosi ty and Sur f aceTensi on Dat e J Phys Chem Ref Dat a 3 1) , 1974

123 Taube and B Dawudi Thermscher Krei sl auf i n ei nem Sal zschmei ze- Reakt or m tAusser em War meaust auscher Ei dg I n s t f u e r Reakt or f orschung i n t e r n a lr e p o r t )TM HL- 270 Oct ober 1975

124 Desyat ni k V N S P Raspopi n and K Tri f onov Vi scosi ty of ThCI 4 MgCl 2 SystemMel t s I zvesti ya Vvsshi khUchebnykh Zavedeni i Khi mva i Khi m cheskaya Teknol ogi ya19 3) : 351- 354 1976

125 Desyatni k V N I Nechaev and Yu P Cher vi nski i Vi s c o s i t i e sof Mol t en Mi xt ur esof Urani um Tetr af l uori de w t h Al kal i F luor i des Sovi et J ournal of Atomc Ener gy 46 5):

408- 409 1979

126 Bauman T C and L T Overstreet Corr osi onand Pi pi ng Materi al s i n t he CPIChem cal Engi neeri ng 85 8): 59- 68 1978

127 Lumsden J Thermodynam cs of Mol t en Sa l t Mi xt ur es Academ c P r e s s ,New York 1966

128 Argonne Nati onal Laboratory Reactor Physi cs Constants ANL- 5800 Second Edi ti on J u l y ,

1963 p 594

129 Engl e J r A Users Manual f or ANI SN One- Di mensi onal Di screte Or di nat esTransport Code w t h Ani sot ropi cS c a t t e r i n g ,Oak Ri dge Nati onal Laboratory TennesseeK- 1693 March 30 1967

130 Gr eens N e t al MPX Modul ar Code Syst em f or Generat i ng Coupl edMul t i gr oupNeutron- Gamma L i b r a r i e sf r o mENDF/ B Oak Ri dge Nati onal LaboratoryTennessee ORNL- TM3706 March 1976

131 Engel J R H T Kerr and E J Al l en Nucl ear Characteri sti cs of a 1000- MWeMol t en-Sal t Br eeder Reactor Tnans. ANS 22 705 1975



132 Cal amand, Cr os s Sect i ons f o r Fi s si onNeut r on Spect r umI nduced React i ons, Handbookon Nucl ear Acti vat i onCross Sect i ons, l AEA Techni cal Repor t s Seri es No 156, Vi enna,1971

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