ML20151X057

Reports on Completion of Review of Application by Util for Authorization to Construct Plant & Informs That ACRS Believes That Proposed Reactor Can Be Constructed W/ Reasonable Assurance of Operation W/O Risk to Public Safety

ML20151X057
Person / Time
Site:	Diablo Canyon, 05000000
Issue date:	06/15/1967
From:	Palladino N Advisory Committee on Reactor Safeguards
To:	Seaborg G US ATOMIC ENERGY COMMISSION (AEC)
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References
FOIA-88-156 NUDOCS 8808250211
Download: ML20151X057 (4)

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• ADVISORY CC,MMITTEE ON REACTOR SAFEGUARDS-UNITCO STATES ATOMIC ENERGY COMMISSION Vs ASHINGToN. D.C. 20548 ,

JUN 151967 . .

Honorable Glenn T. Seaborg Chairman . ,

U. S. Atomic Energy Cccciosion Washington, D. C.

Subject:

REPORT ON VERM0liI YAIEEE HUCLEAR POWER 6"IATION Daar Dr. Seaborg: .

At ito cichty-sixth mucting, on Juno 8-10, 1967. the Advisory Comittee on Reactor Safeguards completed its ruview of the application by Vermont Yankco Nucioar Power Corporation for authorization to construct the Vermont

• Yankco Nuclear Power Station. This project was previously considered at ACRS Subcoc:mittee acet'ngs held in Washington, D. C. on May 10, 19673 and in Vornant on June 7, .)67. On the latter dato, the Subcon:nittee also -

visited the reactor oite. During its review, the Committee had the benea

• fit of diccussions with repreocntatives of Vermont Yankee Nuclear Power ,

Corporation, Ceneral Electric Company, EBASCO Services Incorporatad, Chicago Bridge and Iron Company, and the AEC Regulatory Staff. The Co=sittco also had the benofit of the documents listed below. .,...

Tho Vernant Yankco Nucioar Power Station is to be located in southern f.

Vermont, on the west bank of the Connecticut River in the town of Vornon_. .

'Iho Vormat Yankoo reactor will be a single cycle, forced circulation 4* ,

! boiling vator unit with a design power level of 1593 W(t). The average core power density of the Vermnt Yankee unit is essentially the same as that of the previously reviewod Browns Ferry reactors, and the complex of .

l emurgency core cooling systems is similar to that proposed for this Brovns Ferry reactors. The Committeo bolieves that several of the connents m&de in the March 14, 1967 report on Brovns Ferry apply to the Vermont Yankee .'

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4 application:

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1.. Analysio indicates that a large fraction of the reactor fuel .

- elecents mey bo expected to fail in cortain loss-of-coolant i

l accidents. The applicant states that the principal mode of

. failure is expected to be by localized perforation of the clad, a and that damago within the fuoi assembly of such nature or extent i' as to interfere with heat recovat sufficiently to cause clad molting would not occur. The Cocxnittoo believes that additional avidenco, both analytical and experimental, is needed and should be obtatand to demountrate that t.his model is adequately acacarv-l .

ati%r for the power denotty and fuer Buruup proposad.*

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Honorchic G1can T. Scab'org JUN 151967

2. Tho app?.icant considers th9 pocaibility of colting cnd subscquent .

disintcarction of a portion of a fuoi acsembly, by inlot coolant orifico blochago or by cthor meano, to be remoto. Houcvor, the resulcina of fecto in terms of fiosion product rolcaso, local high pressuro production, cnd pocoibio initiation of failuro in adja- -

cent fuel cic ants are not well known. Information should bo developed to shou that cuch av incident vill not load to unaccept-oblo conditions.*

3. A linear heat scacration rato of 28 KJ/ft is used by tho applicant as a fuci element damage limit. Expericental verification of this critorion is incomplete, and the applicant plans to conduct addi-tional testo. The Committoo recommends that such tests includo heat generation rates in exccas of those calculated for the worst anticipated trcnaient and fuoi burnups co:parablo to the maxicum c:.pccted in the reactor.*

4. In a loss-of-coolant accident, the coro spray and floodin3 systems arc roc,uired to function effectively under circumstancca in which coma arcos of fuel clad may have attained temperatures higher than thoco at which cuch cooling ccchanis=s havo been tested to date.

The applicant is conducting testo of these devicos at increased ec=poraturcs and has reported preliminary resulta which aro promisins. The Committec again urace that thoso costs be extended /*

to temperatures as high as practicable. The use of stainless croci in these tests for simulation of the Zircaloy clad appears i suitabic, but soma corroborating tests e= ploying Zircaloy should i

bo included. .

The reactor vessc1 for Vercon Yankco will be a field-fabricated vessel

j. quito ci=ilar to that proposed for the previously revicued Monticollo The Co=mittco recommends that great care and j Nuclear Generating Plant. .

diligence be exercised in the quality control program for this vessel to 1

casure the soundnoss of this important plant component.

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The Co=mitteo continues to cmphasico the importance of quality assurance in fabrication of the primary syctes and of inspection during sorvice life.

Tno Co=mittco reco=mendo that the applicant imple=ent those improvements in primary system quality which are practical with current technolo8y.*

Tho integrity of Vernon Dam, just downstream of 'the plant site, is essential to maintain the norcal coolins water supply to the plant. The applicant has .

cxamined the design of the dem and states that it should withstand, without I

gross failure, the maximum hypothetical carthquake selected for the site.

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Honorablo G1ct.n T. Scaborg dlfl 15 667 .

He hoo proposed, however, to provido an alternato moans of recoving shutdown heat from the plant in the ovent that the rivor icvol should fall bolov the normal cooling water inict. The Cocmitteo beliovos that ohutdown heat temoval can be accomplished by one r f the soveral methods

• being considered by the applicant.

The Cos ittoo recommando that the applicant givo special attention to the . -

design of critical cicments of the plant piping, including the dryvelle . , ,

torus connections, to ensuro that theco closents ara not overstrassed under caximus carthquako forces.

irculation loops Tho applicant propoces to uco sensing devices in i s of the reactor to detect the location of a pipo bre .. Signals itom theso devices vould bo used automatically to scicct various valvo actions that t j aro esacntial to the proper operation of the cmargency coro cooling systces.

In vicu of tho i=portance of the proper valve actiono in the unlikely event '

. of a major pipo break, the Co=mittoc recoc=cada that the consing instru=on-I tation and valve control cyctem be designed to full reactor protection system standards, and that consideration be given to providing more than one type of sensing devico in the system.

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Fuol clad te:peraturco follouing a secam line break should be further ,,

cvaluated during detailed design, wi-h due attention to using conservative assu=ptions and meihods in calculating these temperaturos. Steam lino l' /,

isolation valvo closure tices as short as thrco seconds may be required l:4 to maintain acceptably low fuc1 clad temperatures in this accident. The applicant has stated that isolation valvos with closure times adjustable

' from 3 to 10 seconds will be obtained for the plant.

Tho rod block monitor cystem for the Vercont Yankeo roactor is a two-channel system, with one channel required for rod blocking action. Tho -

applicant has propoacd that, if ono channel is bypasood for maintenanco, t an appropriato1y short interval between ecsts vill be used for the oper-

- ating channol. The Committeo believen that, if one channol of the rod block monitor system to to bo out of service for a long period of time, other ceasurcs, in addition to frequent tooting of the operative channel, should be taken to onsure that improper rod withdrawal is not allowed to .

occur.

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In view of the high design power density of the coro, an especially careful and cxtensiva start-up program will be required for this plant. If the start-up program or the additional information on fuel behavior referred to above should fail to confirm adequately tho dcoignor's expectations, r plant modifications or restrictions on oporation may be appropriate. - ,

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JUN 15 is57 1:enorabic Glenn T. Cer';oig .4- .,

Yhc Advicory Coraittco cc -- . :,r Safeguarda believes that the ite=c

=:ntioned chovo can be rc:.r,?wed during con:truction of the reactor cnd '

chould be followed by thc Rc3nla:ory Staf f. On the bacio of the foro-goin; co=: cats, and in vic.7 of the fcvorchic characteriotics of the oite, I the Co==ittec belicvco that the propcced rocctor can bo conatructed at .

the Vernon sito with rccconabic acscrance that it can be operated with- '

out undue risk to the health and safety of the public.

Sincorcly youro, 1

0.11GINAL SIONED BY

' N. J. PALLADINO U. J. Palladino Chaireca

• The Co==ittee believes that theco matters arc of significance for all large vct.cr-cooled power reactors, and warrant careful attention.

Reforcnecc:

1. Lmtter from Vermon: Yanhec nucicar Powcr Corporation, dated November 30, ,:

1966, includins Licen:o Application.Pover Station Plant Design and Analyais Report,

2. Ver on: Y nkco Eucicc Volu=cs I, II, cnd III. ..

3. Letter frcm Vermont Y:nhec Uuclear Pcuer Corporation, dated January 10, 1967, with Aacnd :nb Mo.1 to Licence Application. ,

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4. Letter from Vcraonc Ycnkco Nuclear Power Corporation, dated January 23, 1967, with Amendment No. 2 to 7.icence Application.

5. Letter fro: Ver=cnt Y nhec Nuclear Power Corporation, dated April 12, 1967, with A=:ndment No. 3 tc Licence Application.

6. Letter fro = Vercont Yanhec Uucicar Power Corporation, dated April 28, 1967, with Amend =0nt Ko, 4 to License Application.

7. Letter from Vorcont Y:nkco Nuclear Power Corporation, dated May 19, '

1967, with Amendment no. 5 to Licence Application.

8. Letter from Verton Yankee Nuclear Power Corporation, dated May 24, 1967, with Amend: cat No. 6 to License Application.

9. A=cndment No, 7 to Licence Application, dated June 2,1967.

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