ML20086E747

AO 74-03:on 740204,LPCI Differential Pressure Indicating Switch 2-137B Failed to Indicate Properly Upon Isolation from Normal Sys Pressure W/Bypass Valve Open.Cause Not Stated.Sensor Replaced

ML20086E747
Person / Time
Site:	Vermont Yankee
Issue date:	02/04/1974
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E739	List: ML20086E732 ML20086E747
References
AO-74-03, AO-74-3, VYV-3155, NUDOCS 8312070506
Download: ML20086E747 (1)

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( -VERMONT YANKEE NUCLEAR POWER CORPORATION SEVENTY SCVCN OROVE STHECT Ru ri.Asn, Vtde10NT 03701 VYV-3155 amv Toi P.O.DOX 157 VERNON. VERMONT c5354 February 4, 1974

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United States Atomic Energy Commission l5

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birectorate of Regulatory Operations, Region I 631 Park Avenue g O,7 h11 e ' I b.

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King of Prussia, Pennsylvania 19406 .

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REFERENCE:

Operating License DPR-28 E 4 7*,,f.,f Docket No. 50-271 L . -4 Abnormal Occurrence No. A0-74-03 '

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Cd!i l\ W Gentlemen:

As defined by Technical Specifications for the Vermont Yankee Nuclear Power Station, Section 6.7.B.1, we are reporting the following Abnormal Occurrence as A0-74-03 and confirming our telephone '

conversation with your office. '

On February 4, 1974, at 1300, during conduct of a monthly functional test of the Low Pressure Coolant Injection System, Differential Pressure Indicating Switch 2-137B failed to indicate properly when it was isolated from normal system pressure with its bypass valve open. Under this conditioa, the sensor should have indicated zero PSID, however, it continued to indicate approximately 8 PSID. It was deterrained that this condition was in violation of Technical Specifications, Section 1.0.A.4 in that it could have presented the performance of the intended safety function of an engineered safety feature system. Functionally, this sensor operates as a pressure permissive in the Low Pressure Coolant Injection System Loop Selection Logic and has a redundant sensor which was tested and found to be operating properly thereby maintaining proper system availability.

The reactor was operating at approximately 97% power at the time of this incident.

The sensor was immediately replaced, functionally tested and verified to be operable.

Very truly yours,

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VERMONT YANREE NUCLEAR POWER CORPORA ON 4

8312070506 740211 '

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gDRADOCK05000 B.W. Riley '

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l Plant Superintendent WFC/kbd , g COPY SENT RIT>K)N M