ML19270F491

Responds to NRC Question Re Assumption of Credit for Charging Pump Operation During Small Break LOCA Analysis. Informs of Action Taken to Ensure Safety & Meet NRC Requirements.Will Return to Stretch Power Operating Limits

ML19270F491
Person / Time
Site:	Calvert Cliffs
Issue date:	02/12/1979
From:	Lundvall A BALTIMORE GAS & ELECTRIC CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
NUDOCS 7902140196
Download: ML19270F491 (3)

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BALTIMORE GAS AN D ELECTRIC COM PANY GAS AN D ELECTRIC DUILDING B ALTl M O R E, M A RYL A N D 21203 Fobruar" 12, 1070 ARTHUR E. LU N DVALL, ) R.

v.c c pac s.oc ~ r sum, Of'fice of ?!uclear Pc'tetor Peculation U. 3 '!uclear "crulatory Comicnion Washincton, D. C. 0555 Attn: "r. Robert U Reid, Chief Operatin* Peacto"n Er' inch Fh

'Jivinion of onerntir~ Perctorn Cuhject: "alvert Cl i IPn '!ue ] nrtr I'o ,;er p] 'tn t Unita "on. '

1 2,20-ket '!n c . 5 0 '" 7 A 50 919

EC3 Anal vni n ?- n rm t i on n centinran:

A nunntion vtn nnkel roc en t i:, E' a nerber o" 'rour 't ## c o n c er n i n '-

cno of the accu-ntionn ':ned ir our "-ore ency Core Cooline Cyctem (Fe^P)

Analysen ?ne cpecific question van whether we annu-ad crelit for oneratior of a charr inc n'rm d irine tha nn'tll brenk l onn-of-cool nnt necilent ( En"?. )

analyses.

The method and results cortained i n CE'!PD-197, ""al culation "etholn for the Or Enall Ereak LO% Pvaluntion "odel", are dirnetly 'tnnlie-able to Calve"t Clif"" " nit P'n . 2. "'h i s d o ~r an t h'in toen referenard in all of the ECCC An'11ynen suhnitte ! for both Calvert ClifPn Units cince its incue in Auruct lo7h. Thin incluien relond nutnittalc, an vell as the stretch power (?700 I&t) requent cuhnittalc. CF'!PD-137 vac later nodified by CP'!PD-137, supplenent 1 (January 1977), which vac also referenced in our nuhnittals herinning with the Unit 1 Cycle 3 reload rubnittal, dated Decenter 1, 1077 CF"DD-137 and FFl!PD-137, Surnl ennnt I do not acc'r.e credit for the operation of a el trrinr runn durinr thn nnall treak LOCA. The nnalI break LOCA has always been nhavn to be a 2 ens limiting accident than the Inrre break LOCA for ECCS purnocec. Consequently, in all of the reload and strotch power requesta previously nentioned the arplicable FCCS analynin han alwayn been b'tced on the larce break nodel. W e snall break nodel ( CE'iPD-137 and , later, Supple ent 1) vaa included b: reference as beinr not apnlicable.

During thn latter half of 1o76, while conductin~ the analysec for the Unit !!o. 1 ctretch power request, which vac cubnitted on " arch 2h, 1977, none c' 's in the CE Pnall Ereak Model indic'tted that the analycin nicht ' lueted with leco uncertainty in the nredicted recults if we were to ar- credit for che operation of ore charrine runn. Tn no N

%0' 7902140196

, doing, a significant savings in ran-hours and connuter time vould be achieved, and since the charginc punps are classified ac nafety-related equipment and have operability requirements documented in the license technical specifications , it was felt c.t the tine that thin assunntion was appropriate and was not advernly sicnificant from a cafety standpoint.

Therefore, credit for the uce of one charging punp vas assumed, and the cnall break was acain stated as being lesc liriting than the larre break. ?!o chance was ever made to the reference to CENPD-137 and Sunplement 1 because thene documents describe the nethods applicable to all rnall break analynes, whereas the charging punp accunption van baing nade on a specific nlant analysis. Consequently, the channe in assumptions to include a charginc punn was never specifically noted in the stretch power requests or cubcequent reload requests to the NRC.

In light of the above developnent and as dincussed in telephone conversations with your staff, ve have taken the following prudent actions.

1. We have requested Combuction Engineerinc (CE) to conduct either a comparative analyais for other neoping analysis to deternine if a vorst cace snall break ECCS analysis ascuning no chargine punn vould likely conclude that the small break LOCA is still less liniting than the larre break.

?. Pending the results of the above analysis, we have reduced powcr on both Calvert Cliffs Units to 2560 MWt, the authorized power level prior to tho anproval of ntretch power (2700 ?Nt).

If the renults of the analysis are favorable, we intend to return to the stretch power creratine limits.

3. We have also requested CF to conduct the vorst case nnall break analysis assuming no charging pump.

h. We have verified that a single failure analysic var perforned on the charging systen using the criteria at that tine, i.e.

active failures only, and that no charring runns were accuned on the steam line b cak analvsis.

The Dlant Onerationc and Fafety Reviev Connittee and the Off-Site Fafety and Review Connittee met on this natter on February 9,1979 and concluded that the above actions are prudent and sufficient to ensure no adverse impact on the health and safety of the public.

The Office of Insnection and Enforcement vnc notified of the above developnent by telephone on February 9, 1979 This letter cerves as the initial confirnation of that telephone notification. Subsequent reports shall be made as required.

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Ue vill inforn you by telenhone of the results of the cor.nc.rative or sconinr' analysis as soon as ve ret then. Assuninc favorable results, we intend to return to the stretch power operating limits at that time, and ernect that further discuccions may then be required to reviev what further actions may be necessary to resolve this issue satisfactorily.

Very truly yourc, , ,

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f 54_j._'< , . , t n ~c d'*:= W ,

cc - J. A. Biddison, Fsquire G . F. "'rowbridge , Esquire

'fr. E. L. Conner , Jr , !!PC Hr. P. W. Kruse, CF

?!r . D. P. Johnson, OI?cF , Kinr* of Prussia