ML20086E432

AO 74-10:on 740626,HPCI Inverter Tripped,Rendering HPCI Sys Inoperable.Caused by Poor Connection Between Printed Circuit Board & Companion Jack.Connections Cleaned

ML20086E432
Person / Time
Site:	Vermont Yankee
Issue date:	07/03/1974
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E434	List: ML20086E432 ML20086E437
References
AO-74-10, VYV-3319, NUDOCS 8312070152
Download: ML20086E432 (2)

Text

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- VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SEVEN OROVC STRCC1 ,

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VERNON, VERMONT oS354 July 3, 1974 b //O, Director 4 b

k OOyj g Directorate of Regulatory Operations, Region I United States Atomic Energy Commission 631 Park Avenue 9 Es,} J g 78% .-

King of Prussia, Pennsylvania 19405 to 7

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REFERENCE:

Operating License DPR-28 Docket No. 50-271 Abnormal Occurrence No. A0-74-10 (10 Day Report) 3/

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Dear Sir:

As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7, we are reporting the following Abnormal Occurrence as A0-74-10.

at la2a on June 40, lyi4, auring normat plant operation, tne nrci inverter tripped, rendering the HPCI system inoperable. The inoperability ['

of the HPCI system is in violation of the Limiting Condition for Operation as defined in Section 3.5.E.1 of the Technical Specifications which states in part that the HPCI system shall be operable whenever there is irradiated fuel in the reactor vessel and reactor pressure is greater than 150 psig.-

The reactor was operating at 79% power at the time of this occurrence.

The inverter was replaced with an operable spare and the HPCI system was declared operable at 1620. During the time span of HPCI inoperability, t surveillance testing was initiated as required by Techaical Specifications ,

Section 4.5.E.2 and was terminated when the HPCI system was made operable.  !

It was subsequently determined that there was a poor connection betveen a printed circuit board and its companion jack. The connections were cleaned, the printed circuit board was re-installed into the inverter and the inverter  :

tested satisfactorily after operating for 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> on the bench.

The Plant Operations Review Committee met to review the incident and

{ concluded that actions taken as a result of this occurrence were proper and further concluded the faulty electrical connection was an isolated incident .

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5-COPY SENT REGION  ! >= _ _

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[a'T v Directorate of Regulatory Operations, Region I July 3, 1974 Page 2 of component malfunction and that'no further action is required.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION

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B. W. Riley \

Plant Superintendent WPM /sjp O

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