ML20085G266

AO BFAO-50-260/7429W:on 741124,main Steam Relief Valve FCV-1-31 Failed to Reset Properly After Manually Opened. Caused by Excessive Pilot Valve Leakage.Valve Replaced. Installation Monitored

ML20085G266
Person / Time
Site:	Browns Ferry
Issue date:	12/04/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G269	List: ML20085G266
References
NUDOCS 8308240738
Download: ML20085G266 (3)

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) {v ty ABI!0RI!AL OCCURRE!CE REFORT Report I:o. : BFAO-50-260/7429W

• Report Date: December 4, 1974 Occurrence Date: Iovember 24, 1974 Facility: Browns Ferry liuclear Plant unit 2 Identification of Occurrence Execcnive blowdom of nain relief valve FCV-1-31 on I ovember 24, 1974, at 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br />.

Conditions Prior to Occurrence The reactor was operating at approximately 75-percent power. ~

Descrintion of Occurrence While conducting a startup test, main steam relief valve FCV-1-31 failed to properly reccat after it was manually opened. Pressure decreased to apprcxi-nately 570 psig before the valve rescated.

Desirnation of imnarent Ceuce of Occurrence Fron dicassembly and inspection it is concluded that the caloperation can be attributcd to exccssive pilot valve leakat;e. Tnis valve had not been pressure actuated since being placed in cervice. It is probable that the pilot had been leaking since installation.

Analysic of Occurrence The vessel prescure dropped from approxirc:.tely 960 psig to approximately 570 psig in about six minutes. Tne coolant terocrature at the recircule. tion pu g diccharge 5 changed approxim tely 120 F. in one hour. All auxiliary equipnent oport.ted satisfactorily. Tcere uere no adverse effects to the public health and cafety.

There were no radioactive natorials released to the environnent. The trcnsient in being studied in conjunction with vencel ucoge factorc. Preliminary investigation revealc no significant detrimental effects on vessel usage.

Corrective Action The valve that failed uns replaced with a new relief valve. Subscquent disacce=bly and inspection of the failed relief valve revealed a leaking pilot valve. Tne nulufacturer's reprecentative uns present during thic disacccmbly and incpection.

Failure Data Previous failurec are reported on Abnormal Occurrence Reports BFAO-7426U, unit 1; h?AO-749W, unit 1; BFAO-7349W, unit 1; and EFAO-7314U, unit 1.

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b y.cnufacturer: Target Rock Corporation; lbdel 67F Size: 6" inlet; 10" outlet Design pressure - 1,200 psi; cetpoint 1,100 psig + 11 psi I Cepe. city - 600,000 lb/hrcaturatedsteam

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__5 Mr. Edscn G. Case Acting Director of Licensing <d Q .f Office of Regulation W -

U.S. Atomic Energy Cornission j Washington, DC 20545 1 ,

Dear Mr. Case:

e i TEIUTESSEE VALLEY AUTHORITY - EROUNS FERRY NUCLEAR PLANT UITIT 2 -

0 DOCKET NO. 50-260 - FACILITY OPERATING LICENSE DPR ABNORMAL OCCURRENCEREPORTBFAO-50-260/7429W 2

j The enclosed report is to provide details concerning excessive blow- j down of ncin relief valve FCV-1-31 on november 24, 1974, at 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br /> cnd is submitted in accordance with Appendix A to Regulatory j

Guide 1.16, Revisica 1, October 1973 This event occurred on Browns

. Ferry Unclear Plant unit 2.

Very truly yours, y TEInlESSEE VALLEY AUTHORITY g M 2

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, E. F. Thomas tW$ h '$ i Director of Power Production f h C# '-

j Enclosure

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Mr. Nortan C. I:oseley, Director

. Region II Regulatory Operations Office, USAEC 1 p 230 Peachtree Street, NW. , Suite 818 J3' A Atlanta, Georgia 30303 qd l

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