ML20084A972

Ro:On 741008,Westinghouse Informed Util That Safety Injection Sys Delivery Curve Employed for Steam Line Break Accident Analysis Inconsistent W/Analyses Used for Recent Loca.Util to Maintain Shutdown Margin of at Least 2.45%

ML20084A972
Person / Time
Site:	Ginna
Issue date:	11/07/1974
From:	White L ROCHESTER GAS & ELECTRIC CORP.
To:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20084A958	List: ML20084A972
References
NUDOCS 8304060047
Download: ML20084A972 (1)

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ROCHESTER CAS U D ELE &ic CORPORATION 89 EAST AVEN e ROCliES TER, ll.y. .t M 9 Er 7

tion u wuait. JR inter o e uc t rae siot eer sera coot ns 5 4 b.2 700 November 7,1974 7 Mr. James P. O'Reilly '

r Director

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U.S. Atomic Energy Commission b Directorate of Regulatory Operations / -

Region I N G31 Park Avenue l'ing of Prussia, Pennsylvania 19406 m

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Subject:

Unusual Event - R.E. Ginna Nuclear Power Plant Unit No.1 '-

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Docket No. 50-244 ' '

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Dear Mr. O'Reilly:

Rochester Cas and Electric Corporatiori was informed at a meeting on

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October 8,1974 by Westinghouse Electric Co'r peration that the Safety Injection h System delivery curve employed for the Steam LUu Preak Accident Analysia (SLilA Analysis) was inconsistent with that used for recent Loss of. Coolant =

y Accident Analyses. The delivery curve had been revised subsequent to the most recent SLBA Analycis, rcrferr'od by Westinghousc in I cbrusrv 1971 to cccount for the as-built piping configuration and operatio +] characteristics and to _

p_ include a provision for system degradation over'the life of the plant. Those -

. revisions resulted in a lowrsing of the delivery curve. '

{ Preliminary analyses performed by Westinghouse with conservativo reactivity .

3 a pLrameters demonstrate that a shutdown margin of 2.45%Ak/k will insure that all f design criteria are met. The calculated shutdown margin for the present fuci a

$ cycle, Cycle 4, which includes provision for the most reactive contrei rod being stuck out of the core and includas a 10% design allowance,'2s 2.48%$k/k at E the end of the cycle ( 0 ppta boron) with equilibrium ::enon and is 0.25G Ak/k

[ ilt the haginning of the cycle with equilibrium xenon. The shutdown m:rgir 7 _ required by the Technical Snecifications is 1.9% Ak/k at the end of the cycle. T Ei - -

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} Roc 60 ster Gat and Electric CorporMioil has asked Westinghouse to perform' h g additional analyses in order to minimize the shutdown margin required to meet L all design objectives. In the interim, P.G&E will maiittain a chutdown marcin '

E at least 2.45% Ah/k. -

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2,p Very truly youri , -

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