ML20085L972

AO BFAO-7411W:on 740221,during Routine Testing,Check Light for Suppression Chamber to Drywell Vacuum Breaker FCV-64-28M Failed to Go Out When Valve Operated.Caused by Limit Switch Failure.Circuit Will Be Repaired

ML20085L972
Person / Time
Site:	Browns Ferry
Issue date:	03/01/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085L978	List: ML20085L972 ML20085L979
References
AO-BFAO-7411W, NUDOCS 8311070053
Download: ML20085L972 (2)

Text

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TENNESSEE VALLEY AUTHOptlTY r**33 CHATTANOOGA, TENNESSEE 1- .i 3740'i L -_!-

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March 1, 1974 ,

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I Mr. John F. O' Leary, Director s .,,

Directorate of Licensing

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Dear Mr. O' Leary:

TENNESSEE VALL"Y AUTHORITY - BROWNS FERRY NUCLEAR PLAUT UNIT 1 -

DOCKET HO. 50-259 - FACILITY OPERATIIU LICENSE DPR ABNOR!'.AL OCCURREICE REPORT BFAO-7411W The enclosed report is to provide details concerning check light failure on suppression chamber to drywell vacuum breaker valve FCV-64-28M which occurred on Browns Ferry nuclear Plant unit 1 on February 21, 1974, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 Very truly yours, TENNESSEE VALLEY NJTHORITY yuE.F. Thomas t Director of Power Production Enclosure CC (Enclosure):

• Mr. Norman C. Moseley, Director Region II Regulatory Operationc Office, USAEC 230 Peachtree Street, UW., Suite 818 Atlanta, Georgia 30303 l

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Report No.: BFAO-7411W Report Date: March 1, 1974 Occurrence Date: February 21, 1974 Facility: Browns Ferry Nuclear Plant unit 1 Identification of Occurrence Check light failure on suppression chamber to drywell vacuum breaker valve TcV-64-28M.

Conditions Drier to Occurrence The reactor was at approxi=ately 50-percent power.

Description of Occurrence During routine surveillance testing of suppression chamber to drywell vacuum breaker valves, the check light for FCV-64-28M failed to go out when the vacuum breaker valve was operated.

Designation of Arcarent Cause of Occurrence The assumed cause of the occurrence is a limit switch failure at the vacuum breaker ve3.ve inside the suppression chamber.

Analysis of occurrence The vacuum breaker is eculpped with switches indicating disc openire to approxir.ately 80 percent open; 3 degrees open and a check switch which indicates fuUy closed. The vacuum breaker valve is considered inoperable for full clos' ire only because the valve position indicating lights confi:=ed ope'"g and closure to within 3 degrees of fully closed. This is an allowable condition in accordance with technical specification 3.7.A.4.b.

Corrective Action The circuit will be inspected and repaired at the earliest opportunity when suppression chr.=ber entry can be made.

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