PNO-V-85-071, on 851007,one of Two Auxiliary Feedwater Pumps Declared Inoperable Due to Failure of Pump Thrust Bearing. Caused by Disintegrated Thrust Bearing Due to Inadequate Lubrication.Bearing Replaced

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PNO-V-85-071:on 851007,one of Two Auxiliary Feedwater Pumps Declared Inoperable Due to Failure of Pump Thrust Bearing. Caused by Disintegrated Thrust Bearing Due to Inadequate Lubrication.Bearing Replaced
ML20133H036
Person / Time
Site: Rancho Seco
Issue date: 10/09/1985
From: Eckhardt J, Myers C
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-85-071, PNO-V-85-71, TAC-59691, NUDOCS 8510160240
Download: ML20133H036 (1)


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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-85-71 Date: 10/9/85 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by Region V staff on this date.

FACILITY: Sacramento Municipal Utility District Licensec Emergency Classification Rancho Seco Nuclear Power Plant Notification of Unusual Event Sacramento County, California Alert Docket No. 50-312 Site Area Emergency General Emergency

_XX_Not Applicable

SUBJECT:

AUXILIARY FEEDWATER PUMP THRUST BEARING FAILURE On October 7, 1985 the licensee declared one of two auxiliary feedwater pumps to be inoperable due to the failure of a pump thrust bearing.

While in hot shutdown, a trip of the auxiliary boiler caused the plant to lose auxiliary steam supplying the operating main fcedwater pump. The electric motor driven auxiliary feedwater pump (B&W, Canada) was manually started and operated for approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> until the auxiliary boiler was restored. Just before securing the auxiliary feedwater pump, an operator noted that the pump outboard bearing casing was hot. The pump bearing i casing temperature was subsequently measured to be 280 degrees F on contact. Proper bearing cooling water was verified.

On subsequent disassembly of the pump, the ball bearing type thrust bearing was found to have  ;

apparently disintegrated due to inadequate lubrication. The licensee determined that the oil slinger for the thrust bearing had been improperly installed. Initial review ,

indicatesthattheimpJoperinstallationmayhavebeendonein1978.

The licensee is proceeding with replacement of the thrust bearing and other pump repairs.

As noted in a Confirmatory Action Letter dated October 4,1985, the licensee will brief Region V prior to restart on its justification for resumption of power operations.

Region V has responded to media inquiries.

This information is current as of 1:30 P.M. (PDT), October 9, 1985.

CONTACT: C. Myers J. Eckhardt FTS 463-3752 (209) 748-2791 DISTRIBUTION 'I ~ Y I a.,,

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