ML19329F881

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RO 80-55/O1T-0:during Review of FSAR Safety Analyses for Boron Dilution Accident Potential,Nonconservatism in Cold Shutdown Analysis Determined.Cause Unknown.Accident Analysis Review Initiated
ML19329F881
Person / Time
Site: North Anna  Dominion icon.png
Issue date: 07/11/1980
From:
VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
References
NUDOCS 8007110300
Download: ML19329F881 (1)


Text

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$ o ~7 - Il Hfteter pqutyggy g;r ACS ' t to D.1p,egog.

Admin. Officer RONS Chier '

RCES Chier-Virginia Electr'ic and Pcwer Cc:pany ~

Frus Chs.t'.

North Anna. Pcwer Station Units 1 and ? - NPF-4, UPF-7 Sfgde dhief, Cccket Nos. 50-338,60-339 P A Officer..

24 Hcur ReportJhle EVant Emgoy Qfic q, tiritten Folic.edip '

  • Q - (% <pson 1 Event: Patent',al Ncccansarvatis , in FEAR Sliery 4.112 sis. for ilacca.Gilucla .

Event during Cold Shutdcan LEil/fl0 Eo-055/ GIT-O curing a review of the FSAR safety analyses for tocca ui'lutian accide..-

it was dotarr.ir.ed that a potential nancanservatis.! may exist in du cold cht dcwn analysis. Sactica 15.2.4.3 states that with a baron concentratiun of 15C0 pra ar.d a dilution ficw rate of 3C0 gra, the reactor cc.ild so critic.1 in 15.5 c.inutes. If this is cc.r. pared with the analysis for hat shi. tuc..,a o o the sra chutdan :.argin, (at least 1.771 S.) uith a tarcn ccccar,tratica .d 13C0 pra ar.d a a 1utica fica cate of 165 gra, ..here ti a , m. tc,e . ! .! t. . ,

c c i t i ca'- la 30.5 c ic...tcs, it appears that ti.a RCS valt:45 ..u ;a to u t..a canditicas are ti.a sa.ia; that is, a full liC5.

This r:ay cot te- a conservative assu1ptica for the call cimiac. .a c.n li t bhen the RCS cay la drained to the centerline of tha RCS iwtieg fue 1.a ,

or inspection activities. This smaller BCS vc,1we (atant 3315 ft4 n./'..

ftJ) Lauld rasult in a tira to criticality of less thaa 16.5 ' i e.a t u s :. c . 4 . :

cald shu tdt...n.

Tha cause of this discrepancy is not kncan at tiiis tire.

1.'a ha'.e initistad a review of the accidant ar.11ysis i s .t..i . . lu 1. i.

as L pticos'in the analysis are not as conservati=sa as p.avicici) Li. c Si.e .

Unit 1 is prasEntly operating in a Staady Stata C;c.jirian at . ', : i. . .

and Unit 2 is in Ecda 3 (Itot Standby).

Since par Tech. 5psc. 3.1.1.3.2, the PG valves to the b h:ca cc i e . . . .:

veriflad tc ha Ic:ked closed within 15 .inutes af ter a pha..iJ .ulat imn o.

makeup activity and the fact that neither unit is in cald 4.nuru:...a p ci6a ;

justificatian for continued operation.

Coreccthe acticns to be taken are panding cc:platica a? r...: c ru . -..c inves tig:.tica.

/Joo?. 5 I6 Yh(

8007110 300 s l