ML20062J036

Primary Coolant Sys Pressure Isolation Valves,Calvert Cliffs Units 1 & 2, Technical Evaluation Rept

ML20062J036
Person / Time
Site:	Calvert Cliffs
Issue date:	07/21/1980
From:	Noell P, Stilwell T FRANKLIN INSTITUTE
To:
Shared Package
ML20062J034	List: ML20062J030 ML20062J036
References
CON-NRC-03-79-118, CON-NRC-3-79-118 NUDOCS 8009150426
Download: ML20062J036 (4)

Text

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TECHNICAL EVALUATION REPORT

• PRIMARY COOLANT SYSTEM i' PRESSURE ISOLATION VALVES BALTIMORE GAS & ELECTRIC COMPANY i

CALVERT CLIFFS UNITS 1 & 2 NRC DOCKET NO.

50-317, 50-318 NRCTACNo 12550, 12S81 FAC Pc.CJECT C5257 N PC CCNTR ACT N O. N RC-C3-79-118 F AC Tt.SK 213, 21-Prepared Cy Franklin Research Center Author:

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N. Noell/T. C. 5:ihc:

The Parkway at Twentieth Street Phi!acelphia. PA 19103

, RC Group Leader:

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N. Noe:.1 Prepared for Nuclear Regulatcry Commissicn Wasnington. D.C. 20555 Lead NRC Engineer

?. J. F0lk Jul:- 21. 1930 This re crt was cre:are: as an a:ccur* c' werk se:nse'ec ey an age 9Cy of the U^ite StaieS Gov 9'"St** Ne'?r er the U"!!e States G 0vernment

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1.0 INTR 00UCTION The NRC staf f has deter =ined tha: certain isolation valve configurations in systems connecting the high pressure Primary Coolant System (PCS) to lower-pressure sys: ens extending outside containment are potentially signi_: can:

con:ributert :o an intersystem less-of-coolant accident (LOCA).

Such configu.

rations have been found to represer.: a significant factor in the risk computed for core melt accidents. The s'equence of events leading to the core mel is i:.itiated by the f ailure of two in-series check valves to function as a pres-sure isolation barrier between the high pressure PCS and a lower-pressure sys:em ex:ending beyond containment. This causes an overpressuriza: ion and rup:ure of the low pressure syste=, which results in a LOCA that bypasses con-

ain=en:.

The NRC has determined tha: :he probabili:y of f ailure of these check va3ves as a pressure isola: ion barrier can.se signi : cant.y reduced, :: :.ne 3

p:e ssure at each valve is con:inuously =enitored, or if each valve is periodi-ca'ly inspected by leakage testing, ultrasonic exacinatien, c: radieg:aphic ine;e::i n.

NRC has e stablished a progra: to previde increased assurance tha:

s;:5 =ultiple isala: ion barriers are in place in all opera:ing Ligh '4a:e; Rea::c plan:s designated OCE Generic I=plementation Activi:y 3-i3.

In a generi: le::e of Feb ruary 23, 1980, :he NRC recues:ed all licensees

iden:ify :he fellcwing talve configura:icns whi:5 =ay exist in any of their plan: sys:e=s ec==unicating wi-5 :he ?CS: 1) tv: che:k valves in series or :)

.: :ne:i talve s i. s eries vi:h a :::s -opera:ed valve (P.C'i).

For plants i:

..i:n va,.ve cenfigura: ions c. concern were.ound to exis:,. censees were e

a fur:her reques:ed to indica:e: 1) whe:her, :o ensure integrity, continuous sur reillance eeriodic tes:ing was :urren:1y being conducted, 2) whe:her an; va.zes of con:ern were.neer. :c lack in:egri:y, and 3) whe:her plan: pr::e-d;res sheuic se revised or plan: redifica:iens be made to in:: ease :eliabili:y.

Frark.in Ke s e a::'.- Cen:e: '?EC' et? requerted b

he NEC te previde :e:h-n::al assis:ance :: ';RC 's 5 -5 a c:i

5y reviewing each '.i:ensee's su:=i::a'.

2;r. r: :riteria pt:vided by the ';EC and verifyin; the licensee's re::::ed

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2.0 CRI~IRIA

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n-l 2.1 Identification Criteria For a piping sys:e= to have a valve configuration of concern,- the follow-j:

ing five items =ust be fulfilled:

l3 1), Tne high-pres'sure syste: =ust be connected to the Primary Coolant System; I;

2)' there must be a high pressure / low pressure in:erface present in the line;

3). this same piping must even:ually lead outside containmen:;

4)

he line must have one of :he valve configura: ions shown in Figure 1; and 5)

he pipe line =us: have a dia=e:e: grea:er than 1-inch.

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3.0 TICF.NICA:. E*.*ALUATION FRC has reviewed the response (Eef. 2 } of the Ealtimore Gas and Elec:ric Conpany (3CE) to NRC's generic letter {Ref.1] concerning the issue of PCS pressure isolation valve configurations for Calvert Cliffs Plant Units 1 6 2.

The licensee s:a:ed tha: none of their piping systems have any of the valve configura: ions of concern, as described by the identification criteria.

FRC independently checked the plan: Piping and Instru=enta: ion Diagra=s (P& ids) [Ref. 3} for piping systems that =ight have hese valve configura-

ions.

In this review of the licensee's rerponse agains: :he PSIDs and the iden:ification criteria, FRC found no valve :enfiguratiens of concern, thus verifying 3GI's findings.

4.0 CONC'.U SIGN S In 3GI's Calver: Cliffs Plan: Uni:s 1 & 2, all piping syste=s larger :har.

1-inch diameter tha: are in:erconnected :c :he PCS are free of the valve con-figurations of concern. Therefore, no futher codifications to :his plan:'s Tecnnical Spe:ificaticas are necessary on :his accoun:..

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Generic NRC le::er, da:ed 2/23/ 50. frc= Mr. D. G. Eisenhut, Depar: men:

c f Opera:ing Reae:::s (DOR), :: Mr. A. E. Lundvall, Jr., 3alti= ore Css and Ilec:ric Cc=panv (SCI).

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Sal:i=cre Gas and Elec:ric Oc=panv's respense :o the generic NRC le::er, datei 2/25/53, fre Mr. A. E. 'undvall, Jr. (301) :o Mr. D. G. Eisenhu:

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