PNO-III-97-072, on 970906,shutdown to Correct Potential Undervoltage Condition During Certain Accident Scenarios Occurred.State of Wi Will Be Notified.Info in Preliminary Notification Reviewed W/Licensee Mgt

PNO-III-97-072:on 970906,shutdown to Correct Potential Undervoltage Condition During Certain Accident Scenarios Occurred.State of Wi Will Be Notified.Info in Preliminary Notification Reviewed W/Licensee Mgt

ML20216C151
Person / Time
Site:	Point Beach
Issue date:	09/08/1997
From:	Mccormickbarg, Mcmurtray T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-97-072, PNO-III-97-72, NUDOCS 9709080232
Download: ML20216C151 (2)

September 8. 1997 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO Ill-97-072 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 Region 111 staff (Lisle. Illinois) on this date.

Facility Licensee Emergency Classification Wisconsin Electric Power Co. Notification of Unusual Event Point Beach 2 Alert Two Rivers. Wisconsin Site Area Emergency l

Dockets: 50-301 General Emergency X Not Applicable

Subject:

SHUTDOWN TO CORRECT A POTENTIAL UNDERVOLTAGE CONDITION DURING CERTAIN ACCIDENT SCENARIOS On September 6. 1996. Unit 2 was shut down to resolve a potential undervoltage condition which might occur during certain loss-of-coolant accidents where there was also a loss of offsite power.

The licensee determined that during specific accident conditions requiring power from emergency diesel generators G01 or G02, the startup of the containment spray pump and the No. 3 service water pump could create a voltage decrease sufficient to cause a trip of the affected 480 volt bus. The electrical loads would then be automatically reloaded onto the bus. This plant's accident analysis. however, does not accommodate this temporary shutoff of electrical power to the containment spray pump, service water pump, and other safety related loads supplied from the 480 volt bus.

The licensee had previously prepared an operability evaluation permitting continued plant operation based on testing used to establish the load profiles required for starting the containment spray pump and the No. 3 service water pump. Further analysis of the test results, however, showed that the actual electrical loads would be higher than shown in the test and could cause an undervoltage trip of the bus under certain accident conditions.

During the outage the licensee intends to install a modification eliminating the undervoltage trip when the emergency diesel generators supply power to the bus. The licensee and the NRC staff are currently reviewing this modification to determine if it will require NRC evaluation and issuance of a license amendment. The outage is expected to last 10 to 14 days.

The State of Wisconsin will be notified. The information in this preliminary notification has been reviewed with licensee management.

90 32 970900 L PNO-III-97-072 PDR u t, aw b {I

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O PAGE 2 P0lNT BEACH 2 - PN '

SEPTEMBER 8. 1997 The licensee issued a news release on the shutdown.

The NRC Operations Center was notified of the impending shutdown at 8:26 p.m. on September 5, 1997. This information is current as of 10 a.m. on l September 8. 1997.

Contact:

TONY MCMURTRAY JAMES MCCORMICK-BARG j (920)755-2309 (630)829-9872 l

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