ML20136B755

Forwards EA Gulbransen Re Tmi.Hydrogen in Cooling Water Should Be Removed & Burned Catalytically to Prevent Buildup of Another Hydrogen Bubble in Reactor

ML20136B755
Person / Time
Site:	Crane
Issue date:	06/13/1979
From:	Heinz J SENATE
To:	Hendrie J NRC COMMISSION (OCM)
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ML19261E774	List: ML19261E773 ML20136B746 ML20136B755
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NUDOCS 7909110570
Download: ML20136B755 (16)

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i Mr. Joseph Hendrie Chairman Nuclear Regulatory Commission 1717 H Street, N. h'.

h'a s h i ng t on, D.C.

20556

Dear Mr. Hendrie:

I appreciate your concern over the Three Mile Island accident.

I am interested in the issue and an accurate analysis of the problem.

Enclosed for your consideration is an analysis by Dr. Gulbransen of the University of Pittsburgh of the events which led to the hydrogen bubble in the reactor during the Three Mile Island accident, as well as two pertinent articles.

If I can be of further assistance please contact me.

Sincerely,

.A n He$ L \\1A Q JI (Ind ted States Senatg in e

JH/jdd enclosures 7909110

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[.,

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• I) april.'0, 1919

1. ,ein tor Jetni !!a i az, 111

c. : ate Office 'h t i l d i n g g q,g,,,

g7 q~. ' '

g

obi ng t on, DC 20310

't o r 4 a ! I n r N ' a x :

4 As a 1cn3 t iae rmoa rch or' e r on the.A iieal ad u t a ll u r:;i ca l properrie. ot /. i re en i a,n md eleconlu-alluys ni 1sa+.

'or of the f acult y of the Npa r timo t of "e t a l la rsic a l. n.u! "a t e ria l o '%inear ias of t he 17a lve rs ity o f P i l t abo r.;h, I nn nd. mitt.ing to eu *y aal;ila and s

cora :tions en the ace blent at the Yhree "tle Tsinad noc1>ar reactor.

Prior to 19 7/4, I teorked.at the '.?outinghause Research Center in

?ittsburgh for nearly 3$ years on the oxidat ten aad corrosion of com-3rcia11y useful metals and alleys i nc l ud ing x,i rcon i o.,

and Zirealoy tr.

I have long.been greatly concerned about the use of /.trecof um alloys as cla 'd i ng for t he uranin.n dio:s ide fuel pellets ta ancione reactors.

My analyais of past and future behavior of the conctor is, briofly,

.as follevs:

The reactor undermnt a n1]ar temperature oscurnfan during hich, from available inforaatton, I auld coaelude that 10 -13 pe rce nt at the Zirealoy cl.id.:.n3 reacte.1*;ith

.s t. Un to f a c n zi ruo tmq dioxide and hydrogen, rhl.s reac tion f urni ched mt of the hy d rogon in the ht,bble at the reactor hyad.

Part of the hydrown pro!>.ubly p, *t rated the oy!de film en the Ztrealoy II claddlas to dinsolve in the etal and to for., xtreentu.n hyd ri de, Z ell j f,

Chis hydride h tu l os hyd re;en ec,o f i l b r ium pre ssu res at the nornal*ederatias terparature of the reactor.

Such reacted hydro;;,on obviously cannot be vented.

(Attached find two papers describing our work on this reaction.)

This wack e ad that hydecsan gas rapidly panatrates the oxide. At defacts nod ndaes apalling of the hydrida and ex tde could occur.

I suggest that this reaction may have occurred in the reactor absorbing the hydrogen bubble.

%'lth or without spalling onbrittlement of the cladding must have occurred with serious danage to the Zircaloy in the reactor.

The spalled zirconium hydrido and zircontum oxido :ould fait to the bottom of the reactor together with tho fool pellets.

The circulating cooling water continues to react with the frenhly spalled zirconium hydride surfaces forring ore xirconium dioxide and hydrogen.

I predict that this reaction will continue until all of the Zircaloy II cladding is reacted.

o n.

w c. w,...,s i.D.m. a m 31

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• nrt1 ?O, 1919

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Page 2 j

I As a ch,ul.t of the abcve analysis ! u r,3c s t the foll In; scceduros:

( l) hJcogen in the coolint; 'ater shoubt be c.aaved and burned catalyt ically to perv. nt botid up of another Sydro,ea bubble in the reactor.

(2)

Che 1.w t cerature Zirealey II - f ater rNet ien will oatinue as noted above. All re1< md gues mst be c

filtered.nd t r. pped b. f o c.f 1.n a I m; to c eve r.+1!"icIive gases and r.1d icac t i'/c pa rt icu l a t.es.

The only sa fe

• i c'.nmical and ceaditicos after in accident like tha t a t

'bree Mile Island is to have all of the Zircoloy II reacted to the oxide.

(3) lijdrc;en in the c.f reulating cooling.:ater r.ust be c:onitored and removed until a near zero value is attained to insure that no metal and hydride remains.

A temperature excursion with unreacted metal and hydride in the reac tor ceuld lead to re ferration of the hydrogen bubble.

Hydrogen gangas of high :ensitivity are now availabic or could be ccde ia a short time.

(4)

I an ruch ccacerned about the effect of hydrogen en the reactor eessel and piping.

I strongly recomend that e verfrents he nde on hydrogen embrittlement of the alleys aced in the reactor and piping under ccaditions stuulating these,:hich occurred in the reactor.

(3)

I trengly reconmend that experinents should be nade on the ef fect of hydrogen in the cooling water at high prossure on pec oxidi/ed /.iccaloy II to evaluate the penetration and pick-up of hydregen as a function of teaperature.nd pressure.

(6)

I ccec -end calculations on how r.uch of a rapid steam or ' cater re1ction could occur before Zircaloy II the hydrogen forned embrittles the cladding and ruins the reactor.

(7)

Sensitive hydrogen gauges should be installed on the prirary and secondary loops and on the reactor itself to ronitor the Zircaloy II - steara and water reac tion.

I should like to re,ncat that these suggestions are based on ex-tensive research in the field of gas-metal reactions.

'y own basic research on /.irconium began in 1947 before the formatien of the

'.*es t i n3 on ;c 2e t t is ! tocic Pe cor I.iberatories.

Tuenty years of nearly 1

continuous rescacch eas conducted on the reactiens of zirconium,

"anator.1An "einz, III April 20, 1979 P/ <;c 2

/. t re a loy I f, /.t rea l oy IV and t he o the r z i r c on ium a l l oys s.'i t h o >.'.t;c.n, #

air, nitro ~,en and water vapor over a tenperature range of 25*C to Q)0 C and at presr. ores of a few torr to over 100 atroupheres.

This work 'tas report.ed in 25 papers and rany research roports to the b'estin:; house

'GrctrIc Corporation.

' ny 1 port ent tec1.nical proble as ';cre nolved including the colubility of hydrogen in z!rconfo a, Lt<e cru tal structire and inn 3a of henoneneity of. i re so f rn hyd ri.10, P r M.,.,. the r..i e or d i r r.r; tun of hvd roven in <.lrci a ton, the role of ox'de riles ca hyd regen adsorpt i n, the rate of o :Idatica of zircunium in 0::,3en, the rat a of n i r r *.ia

.:-r cit t en la n it reyn, t he L,ge s of hyd r.23en react hen w ith z i r.m:nt n.n f a to r a a l t ic c c pe m.N, :i e c ite of r

ra:).ct icn of zi rconium alleys in tator at hl ;b pr.

-are d tha...' ator i

'iO*C.

1: o

's M ta of 7.irenicy It in enut t' 1 cw i g s t e.i..i a t L.

in addition to the above atudies of diccet intarost to noclear reactors, I have rade studies on the cettcring r.neticos of zirconinen f

for removing trace aciounts of reactive casas such as hydre en, ex;.;;en

[

s nnd '.cator vapor in inert gases for use in incan.4sc.at 1,.

p.

I hwe also studied the high terparature reactions of zirceo o, w i t h os.; ga n t o r

ua.<! nice the li@ t outpnt and color tamperature of flash *:o P:s.

I stren3 y urge your sericus considerat!on of the suggestions I 1

have rade br:re.

[ write as an iadividual ecientist d.eply cencarned abant the prob 1r.,s of nuclear pcwor.

?,e s pec t t'u l ly,

l'ari 3. Gulbranson, Ph.D., P.E.

.id j unc t Cescarch Professor Departnent of

• e tallurgical and l'aturials Engineering l'a i;crsity of Fi t t 3borgh EAC/nk

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Reaction of Hydrogen with Preoxidized Zircoloy-2 at 300 to 400"C Earl A. Gulbransen and Kenneth F. Andrew Research Laboraturies, Westinghouse Dectric Corporation, Puttsburgh, Pennsyleania AUSTRACT 300*-100*C was The permeability of preformed oxide films to hydrogen at studied. Two types of reactions v.ere observed. If the oxide film was per-meable, a general reaction occurred w ith the formation of ziiconium hy dride phases on the surf ace. If the oxide film was rdritively impt rmeable, reaction ocr:urred at the edges of the sample where defects probably exist in the oxide.

The reaction starts at loct,lized areas and >preads through the nu.tal with hy dride and oxide film spalling from the metal continually.

The mechani>m of the teaction of hydrogen with Zirconium reacts with hydrogen at temperatures puie Zr was considet ed earlier (4). The permeability up to 550'C to form stable hydrides of the metal of several types and thicknes>es of oxide films to hy-when the hydrogen concentration exceeds the ter-minal >olubility (1.2). The formation of a h dride drogen was deter mined at 15 0 ' C.

The results 3

.-howed that the oxide film formed at ioom temper-phase on the surface and in the metal causes major atur e o.. auinded und e!t aned meta! 3 ample; ofTo ed changes m the phy.<ical and chernical prope:nvr of more re.i:,tance to hydtogen per meation than thicker the metal or alloy (3),

oude films foimed at 250'C and higher. Oxygen Hydride phases can form readily at 400'C since the terminal solubility is only 1.P,6 nt.1 or 200 ;>pm aad nitto;;en di>.-olved in the rnetal phase had no effect on the rate of permeation when compared to by weight of hy drogen. One of the ef'ective barriers an eNide-fiee..u r f ace. Chemically polished sur-to reaction cf 7r at 300'-400'C with hydin;wn i: a f ato et 7; wer e impe: me..bic to hy dr ogen at 150'C.

.-urface oxide film (4),

With the develo; ment of Zr-Sn alloys for u.-e in Experimental nucl ear power readora, it ia of Inte:e.-t to.-tudy the pritm:.b:llty of -cut al types of o ide film-in hy.

Alta rctux.-The vacuum triics obalsnee apparatus w.i> u n ti (fe) for piepering the oxide fihn3 and for dru';en 6t temper atu:ss of.500'-400'C and Se ef-detet:r.inin;; the t e.n tion w;th h drogen. Details of 3

fccts of the hydro;en ract!en on the a!!oy,

J' C i1R t W i..

.c.

'10 i

n., per cm as

' s.t"'l n.iinst the time in Tame 1. CH d cad uccieepph.c oco'on of Z..nley.2

<n m.s Cui ve A., hows the time course for the n

_ _ _ _ _. ~ _ _. -

M,:

ed.anple containin:t the rooin tempm at n.e nu.w.s.: rut e.:iv f,im. A ap,d en ption of hydr opn, ccui 3 with c% ment wi r, nement

.vi r, the 6mpontion Zr H, n (43 at. hythogen) being Zr Major Hf 0.0035 formed in 2 min of reaction. Although the hydrogen

" ' " ~

13

• N 0.0038 tinued during evacuation until the hydrogen pres-Ni 0.055*

H 0 0020 sure was reduued to a value curresponding to the Cr 0.100' O

0.1400 decomposition pieuure characteristic of the hy-At 0.0045 dride phase (about 10" mm Hg) (2).

On cooling to ioom temperature, the sample was cw maat.

found to be brittle and cracked readily into a num-the apparatus and method have been described (5).

ber of pieces. Since the terminal solubility was only Pure hydrog.m was prepared by diffusing a pur2-1.06 at. G at 400'C, most of the hydrogen was in fled grade of hydrogen through a hot Pd tube.

the hydride phase ZrILi and was concentrated in Samples.-Thick strips of Zircaloy-2 were ob*

the surface layer. A rapid reaction occurred at tained from the Westint; house Atomic Power Divi-400'C although the room temper aturo oxide nini sion and rolled to strips 5 ar.d 10 mil thick. Table I limited the reaction with hydrogen at 150'C.

thows the spectrographic and chemical analyses of Curve B of Fig. I shmvs the results for the chem-ically polished rample. Although the chemical pol.

the alloy.

Some

>hing solution removes metal from the sample, a Samples were abraded and cleaned (6).

of the samples were given a chemical polishing passive type of oxide or corrosion film remains on treatment in a special acid bath having the compo-the alloy. Curve B thows that the paufve film pro-sition: 45% HNO,10G HF, and 45% H.O.

tects the metal for 2 min of reaction time after Steam reacted samples.-These were reacted with which reaction occurs. However, as fast as hydride steam at 309'C for three days to weight gains of is formed. it spalls from the metal giving a weight 118 to 1">5 ghm'. Altheugh most of the oxygen jcss instead of a wei;ht gain. The rate of spalfing forms an external oxide film, some oxygen may increases steadily with time as more surface is ex-dissolve in the metal.

posed for reac: ion. An examination of the epecimen af ter cooling shows that the sample ed",es '.ere the Results and D.iscussion only regl'>ns attacked by hydrogen.

It is concluded that chemical polishing the alloy Comparison of Initic! Pretreating Procedures forms a film which was nearly impermeab!e to hy-Abraded and chemically polished samples of Zir-drogen over the major portion of the surface. How-caloy-2 were reacted at 400'C with pure hydrogen ever, reaction occurred at the sample edges. Since at 5.0 cm Hg pressure. Since the vacuum was better the attack is highly localized, spalling of hydride than 10 ' mm Hg, the samples showed no evidence occurred with a loss of weight. Curves A and B of' for a pick-up of oxygen on heating to the reaction Fig. I were reproducible.

temperature.

Fig. I shows the time course of the hydriding Permeabilit1/ of Preformed Oride Films reaction for both samples. Here weight gam m mt-to flydrogen Zirealoy-2 samples were reacted with pure oxy-soo gen at 400'C to form oxide film thicknes.:es of 10, fa ZrH3,,

24.5. and 73 ug/cm'. These weight gains corres-1 ponded to 615.1510, and 4480A of oxido using the I

Mo

[

conversion factor of 61.5 (6) to relate Angstroms to weight t ain in miciop ams per em'.

/

• 00 ~ l

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70

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0 iO i

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ho

1. C&winn cf

1..it at cwe Mm o, N dn J,ng L #* d " I Z..cSoy.2..:CO'C. 5 0 cm Hg of H, C v,. e A c'st o.Dd

,o:m iu,per:+ure c de htm, curve 6, chitmic s!!y rob.N.d F.; 2 En.o..

m,n o.e.

f 10 g./c t, - cn h,. i..a,y n:5 2 2 9 C. 5 0 u, H d H.

e.. A Mm.

. ' f oi lH l. N o il l(I, C ri'<.

( 4 iiVi d a.h,N 'a!.:i s '.i '

'i

. ~

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• o w an d d. sad u!'er

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• j

'0<w H3 ;, r. w e e g

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- ~ ~ - ~ ~

- ~ - ~ - - - -

- - ~ -

T.n M 1m I

Room tomp

%ne Mat hed hptrcc n, oxide no a p:dling.

}

[

Fme ciacks en l

sui hce.

l Wne flenction at ed ges

""O Chem.

g poli 3hed w ith spalling.

.g

)

10 GIS Wuemreen Reaction at e:d:;es w ith : palling.

I

- kgr un fleaction at (dges

1 5 u

w ith s;,alling.

69. 3. Ellec t of thm unde him (2 4 5,,9 end on Ndodmg

/

73 4i80 i, ray R.: action at ed;;es Zier atoy.2, 400'C, 5 cm Hg of H, o ith 3palhng.

g

.\\

• e mew, roug

-

• w t io 90 ~

g

/,,,

-q f

T d!, H l.

',s -

.f < c MM t.n h b apa re ac tbn of AT y

6

u. e r htmt ort Zuculcy 2 g,

f ib Psepored it.

on. H.O. 3 h s 11 DO*C i

~ ~ ~ ~ --

0

[

h H.olm sa (3

Ume (hr 51 O l O 20 d

r r.o mt en s G

ut i' r es.

y 40 1 rrC(rmn) mn p. n, inkk w Te m p.

.w.

rms g

pg(m;A'y,i.*

'C em Fm iu

-..m t o u wt m o if 42 0 002 f IM 9 310 Joo 2I

• 80 '*

hr.

n 42 o sat in 9.3 :o suo

.s o rw erwtwn m a Iso 4 Ef fnt of th.n oude f Jrn (73 ug/cm') on hydoding

,j'f,'A';%]n, M(ci]y 2. 400*C. 5 0 un Ug of He a gi o,m i,,,

a,,o t,o io 7 V6 0 Oc 2J l '.' 8 i 00 no

$0 r ' e wf o

r. 2 i r, e n thr. g These ramples weic reacted with hydior,en at is u o 007 sie 1,. coo no io ras, races,r.ir. 2 r $7c3Mn in 400*C and 5.0 cm Ifg preput e. Fig. 2. 3, and 4 0 :3 ones n2 a no no

. o r $7/,l $,O.,

au o (.,a in smo no io show the tims courses for the oxidath.n and hydro-

• 2 v., m a i

gen s caction eurves for three npeiiments. If>dio-

~ ~ ~ ~ ~

~

gen was added af ter removing the oxygen and evac-

- - ~ ', ~ ~ ~ ~

• d e f ter % f ought) Pit (MIO uating to a piewute of I x 10' mm lig.

The weight change-time cuives for the h3dingen action occurr ed af ter C br for I cm IIg hydiop:n reaction were similar to Curve B of Fig.1. Af ter pienure and af ter 12 min for 5 0 cm II; hydroge n an induction period, reaction occurred with imme, piessure. The 100'C e.speriments showed scaction diate spalling of hydride. This behavior was char.

in three of thc. four esperiments. The fourth experi-acteristic of a highly localized attack. On cooling, ment would piobably <how reaction if the reaction all.of the samples showed a highly 'ocalized attack time had been exterded.

at the edges.

Fig. 5 show s a photograph of the 350*C-1 cm Table 11 Summarizes the results on this > cries of lig prh +m e exper:mont. The tuurse of the ed;c i

cNperiments. It is cr.ncluded that the oxide films ty pe of > palling ia een cleaily. All uf the camp es weic nearly impeimeable to hydroy,en except at the w hich reacted with hydiogen in this gioup of ex.

edges where localized attack occurs with 1, palling periment-icacted at the edges u shown in Fig. 5.

1 of the hydride ingether with the oxide film.

To pros e that the alloes haene' i, steam-Im d

oxice nlm ie.ict with h.diogen at the edges x."m' i

i tay Stuches on Steam Formed Oxide Films Six damples of Zirealoy 2 wete reacted with ddit actic>n studie.4 w ere made of the spalled nuto-s' cam at 399 C for thace days to form oxide films

al and the remMnmg metal phe The

>tt a ~..

)

of thkknene between 110 155,g/cm'. Tnew thick-treno.hd Zn caloy-2 -ample s eaue d u sth h3d:m n r

neues. weie,3-w; of the 350 g/cm' 6!m thick-at.;00' C rnd 5.0 cre He of If. *. :o e tmhed pet. F.e j

xe. found by Thomas (7) for tions.ition !n the cor-5).

ronon rate. The picknee of hydside in the nicam.

The galled ieacMn pivduct,mc an a m.y d f-reacted Dlms before hydsiding was not tested, fract;on p,.tturn cha:acteristic of the delta-hy dr:de Samples were reacted in the aureceived condi-ph.-c hwinn the compMtion Z: H, (1) with no tit >n with hydropen at pr eput e.4 of 1.14. ; nd 5 0 i.vidt m e of a metal phawe. Tne w ay di'Ir..cKn (m H: and at t(mpeintuies of 100'- 400' C. Toble pitm r. cf the iema:rins metal r.ee a paticin char-

.l M Zr wid. no h ch hfe ; t i chon, AhW h

!!! hows a rummaiy of the oxide thickner-ci. the rw. r ;

3

'c ule n." ctiota ma F e es pi c:ed, t he uno mt u a.*

hydiopn im tion conditinn. and te olto

'oo r '.. " t o dt.t.it by s a a>

d # ' a llon met r r!-

At 300 C no t ex tion oerm ied in 20 hi for a h3 -

IE'

.s l i' ' ! = t 'N (

j! I.

d;'stgi n pl( n..ut e f or 2 4 ett) ItL % hnlc at M C t L4 l'

.U

' ; M t d t i t

'!P-

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