ML20058L296

AO 263/74-12:on 740521,HPCI Turbine Auxiliary Oil Pump Failed to Start.Pump Motor Acceleration Relay Auxiliary Contact Assembly Partially Dislocated.Auxiliary Contact Properly Installed & Sucessfully Tested

ML20058L296
Person / Time
Site:	Monticello
Issue date:	05/30/1974
From:	Mayer L NORTHERN STATES POWER CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
AO-263-74-12, NUDOCS 9105140443
Download: ML20058L296 (3)

Text

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r Regulatory Docket File MSP NORTHERN STATES POWER COMPANY M I N N E A PQ t,,g S . M I N N E S OTA 55401 May 30, 1974 ,

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f N, Mr. J F O' Leary Directorate of Licensing Y '" ,($NfEn r, Office of Regulation JL1/L. b '8 United States Atomic Energy Commission

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Washington, DC 20545 -

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Dear Mr. O' Leary:

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MONTICELID NUCLEAR CENERATING PLINT -

Docket No. 50-263 License No. DPR-22 A0 263/74-12 ,

Inoperability of HPCI Auxiliarv Oil Pumo o r nerating Plant which we are A condition occurred at the Monticello Nuclee c.on 6.7. B.1, Abnormal occurr-reporting to your office in accordance with '-

ance Reports, of the Technical Specification sr Provisional Operating License 1

DPR-22.

On May 21, 1974, during testing of HPCI system modifications which were in-stalled during the recent refueling outage, the HPCI turbine auxiliary oil pump failed to start. Investigation revealed that the pump motor acceleration relay auxilierv contact assembly (see attached figure) was partially dislocated, ,

thus preventing the main morer contactor from energizing.

The i.xiliary contact assembly was properly installed and the oil pump success-fully tested. All other DC motor control centers were inspected for dislocated auxiliary contacts; all were found in good condition.

Routine electrical maintenance was performed on this equipment during the Spring 1974 refueling outage. It is believed that the auxiliary contact assembly was slightly dislocated when maintenance was performed and subsequent operations of the acceleration rela y resulted in further dislocation until the auxiliary contact failed to actuate. To prevent a recurrence, an inspection of the auxiliary contact assembly will be incorporated into the electrical maintenance procedure.

This occurrence did not affect safe operation of the plant since the RCIC ,

i and Automatic Pressure Relief systems were fully operable during the time that the auxiliary oil pump was inoperable.

9105140443 740530 CF ADDCK 05000263 CF 1

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NORTHt:.RN STATEC POWER COMF ANY Mr. J F O ' Le ary May 30, 1974 l Page 2 l

Co previous malfunctions of DC powered components have occurr nd due to dislocated auxiliary contacts. It is felt that this is an iso.'.cted incident nd that the planned additions to the maintenance procedures will ensure reliable future performances.

Very truly yours, Y hr L 0 Mayer, PE Director of Nuclear Support Services LOM/lh cc: J G Keppler G Charnoff

linnesota Pollutien Control Agency Attn. E A Pryzina attachment

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