PNO-I-90-059, on 900730,plant Shut Down Due to Excessive RCS Leakage.Util Will Repair Plant Electromatic Relief Valves Found to Be Leaking During Startup.State of Ny Has Been Informed

PNO-I-90-059:on 900730,plant Shut Down Due to Excessive RCS Leakage.Util Will Repair Plant Electromatic Relief Valves Found to Be Leaking During Startup.State of Ny Has Been Informed

ML20056A320
Person / Time
Site:	Nine Mile Point
Issue date:	07/30/1990
From:	Cook B, Meyer G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-90-059, PNO-I-90-59, NUDOCS 9008060374
Download: ML20056A320 (1)

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DCS No: 50220900730 l

. Date: July 30,1990 I PREli.MihARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-90-59 f This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region I i

staff on this date, i

Facility: Licensee Emergency Classification: i Niagara Mohawk Power Corp. X Notification of Unusual Event  ;

Nine Mile Point Unit 1 Alert '

Oswego, New York Site Area Emergency ON 50-220 General Emergency Not Applicable ,

Subject:

NOTIFICATION OF UNUSUAL EVENT FOR NINE MILE POINT UNIT 1: SHUTDOWN REQUIRED DUE TO EXCLSSIVE REACTOR COOLANT SYSTEM LEAKAGE At 11:00 A.M. on July 30, 1990, an Unusual Event was declared at Nine Mile Point  ;

Unit I when reactor coolant system leakage ~1ncreased by greater than 2 gallons per l minute within the prior 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period, Unit Technical Specifications require plant shutdown if this leakage rate limit is exceeded. 4 Niagara Mohawk had identified this increasing leakage condition after noticing increasing levels in the drywell floor drains and had commenced a voluntary reactor shutdown at 10:50 A.M. en July 30, 1990, prior to reaching the Technical Specification '

leakage limit. The reactor shutdown from 1*4 power, 250 degrees F and 25 psig, and subsequent Unusual Event d6claration became mandatory af ter the Technic 61 ,

Specification leakage limit was exceeded at 11:00 A.M. The Unusual Event was '

terminated at 11:20 A.M. on July 30, 1990 when the reduction of reactor system pressure during the shutdown caused system leakage to decrease below 2 gpm. .

In addition to investigation and repair of the condition causing the excessive reactor I coolant system leakage, Niagara Mohawk will repair 2 or 3 of the plant's Electromatic Relief Valves (ERVs) which were found to be leaking during the startup. ,

Niagara Mohawk had received authorization to restart Nine Mile Point Unit 1 on  ;

July 27, 1990 and had commenced unit startup at 1:25 A.M. on July 29, 1990. Region I has responded to media inquiries.

The St6te of New York has been informed. *

' CONTACT: Glenn Meyer Bill Cook, SRI  !

i FTS 346-5183 314-342-4041 i

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9008060374 900730 h_1 -09 HC 3 -

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