ML20058K800

Ro:On 750209,smoke Observed Coming from Motor Starter for Reactor Water Cleanup Discharge Isolation Valve. Investigation Revealed That Shorted Relay Coil Resulted in Overheating of Control Transformer

ML20058K800
Person / Time
Site:	Monticello
Issue date:	02/10/1975
From:	Larson C NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
NUDOCS 9102140418
Download: ML20058K800 (1)

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NORTHERN STATES POWER COMPANY

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}tnticello, Mimesota 55302 I

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Febmary 10,1975 i

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Mr. J. G. Keppler, Director p.

Regian:III 30ffice of Inspection and Enforcetent

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United States Nuclear Regulatory Comission 799EcoseveltRoad Glen 4Ellyn, Illinois 60137 g

Dear Mr. Keppler:

!sNfICEl10 NJCLEAR GENERATING PIM Docket No. 50-263 License No. DPR-22

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On Febmarf 9,1975, smke was obserted cctaing frca the mtor starter for reactor water cleanup discharge ifolatien valve.10 2399.

Investi-gation revealed that a started relay coil resulted in overneating of i

the control transformer in the mtor starter. Failure of the contml transfomer caused the isolation valve to be iraperabic. Neither this I

valve nor another valve in the discharge line was placed in the closed position as required by Technical Specification 3.7 D 2. The failed relay and rotor starter wre replaced and the systea was retumed to r.orm1 cperation within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. Further investigation of this c~ccurrence iscontiming.

Yours verf tgily, (b

g C. 2. lars PlantManager CEl/ma

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