ML20086E724

AO 74-04:on 740223,MSIV Rv 2-71B Failed to Open at Required Setpoint.Cause Under Investigation

ML20086E724
Person / Time
Site:	Vermont Yankee
Issue date:	02/25/1974
From:	Riley B VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML20086E718	List: ML20086E713 ML20086E724
References
AO-74-04, AO-74-4, VYV-3175, NUDOCS 8312070500
Download: ML20086E724 (2)

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VENMO,NT YANKEE NUCLEAR POWER CORPORATION SCVCNTY SCVCN OROVC STRCCT Ru rLAxo, VERMONT O ~,701

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VERNON, VCRMONT 05354 February 25, 1974 8

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co United States Atomic Energy Commission Directorate of Regulatory Operations, Region I N.- t 631 Parh isveaue g g King of Prussia, Pennsylvania 19406  % -

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REFERENCE:

Operating License DPR-28 Docket No. 50-271 p 4j ;;' .h/$

Abnormal Occurrence No. A0-74-04

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As defined by Technical Specifications ,for the Vermont Yankee Nuclear Pouer Station, Section 6.7.B.1, we are reporting the following Abnormal Occurrence as A0-74-04 and confirming our telephone conversation with your office on February 23, 1974.

At approximately 1008 on February 23, 1974, while performing a Main Steam Iselation Valve full closure test as a part of the plant startup test program, one of the four Main Steam Relief Valves, RV 2-71B, failed to open at its required setpoint as referenced in Technical Specifications, Section 2.2.B. It was determined that this condition was in violation of Technical Specifications, Section 1.0.A.1, in that it caused a safety system setting less conservative than the limiting setting established in Section 2. The reactor was in a scrammed condition at the time of the incident and had been operating at approximately 93%

power preceding the occurrence.

The maximum reactor pressure attained throughout the evolution was approximately 1104 psig which was well within the design and Technical

, Specification pressure limits.

Valve RV 2-71B was subsequently manually opened through its

, Control Room panel mounted switch at approximately 700 psig reactor l pressure. The manual opening confirmed valve operability in that mode of operation, r f 8312070500 740301 {

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VERMONT KEE NUCLEAR POWER CORPORATIOR 1

United States Atomic Energy Commission February 25, 1974 Page 2 A plant cooldown was initiated and the immediate program will determine the cause of the valve problem and apply corrective action prior to resuming plant operation.

Very truly yours, VERMONT YANKEE NUCLEAR POOER CORPORATION 0 l h .

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Bradford W. Riley C(

Plant Superintendent WFC/kbd O

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