ML20084H619

AO BFAO-7435W:on 740526,HPCI Isolated on High Steam Flow & HPCI Inboard Containment Isolation Valve FCV 73-2 Could Not Be Reopened.Cause Unknown.Valve Operator & Motor Replaced & Valve Returned to Svc After Functional Testing

ML20084H619
Person / Time
Site:	Browns Ferry
Issue date:	06/05/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H622	List: ML20084H619 ML20084H628
References
AO-BFAO-7435W, NUDOCS 8305040692
Download: ML20084H619 (2)

Text

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I'r. John F. O'Learf, Director Directorate of Licencing Office of Re mlntion U.S. Ator.ic E.nercr C0=iscion Washington, DC 20$45 Deer I:r. 0' Leary:

TEi:UESSEE VALLEi AUT.iORITI - BRO',GiS FERRY UUCLEAR PLAUT UNIT 1 -

DOCEI;T I:0. ';0-2j9 - iACILITI OPEM.TE3 LICENSE DPR !aNO3:'aE OCCiTRTC:05 REPORT 3FAO-7435U The enclosed report is to provide detnils concerning liPCI icolation and is cut.~.itted in cecorder.cc with l'.ppendix A to Regulaton/ Guide 1.lf,, Revision 1, October 1973 Thic event occurred on Browns Ferrf Nuc1cer Finnt unit 1 en 1:ry 26,1974 6

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P.r. Uormn C. ':occley, Director Region II Regulator / Oncraticac Office, USAEC 230 Pecchtree Gtreet, HU., Suite 818 Atlcata, Georgia 30303 r

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1 ABI:0R"AL OCCURPECD REFORT Report No.: EFAO-7435U Report Date: June 5, 1974 Occurrence Date: 1:2y 26, 197h .

Facility: Erovnc Ferry nuclear Plant unit 1 Identificatien of Occurrence ITCI isolation.

Conditions Prior to Cccurrence The reactor nas at 37-percent pouer starting up to renune startup tests at the 100-percent pouer plateau.

Descrintion of Occurrence During the perference of reutine curveillance tccting, IECI isolated on high stecnflow. Following this icolation, the IECI inboard containment isolation valve, FCV 73-2, could not be rcotened. The unit ran brought to the cold shutdown conditica and dryuell entry was made to repair the valvo.

Decirnation of Arpr. rent Cauce of Occurrence The exact cauce of the failure of valve FCV 73-2 ic undetermined. The valve itcclf uc: fcuna t;. u,cc..ute f;;. Q ..iL'.~a; Lluli.e. The m1ve .vLui vye2,2Lv1 , . c.

badly burned and one gear tcoch was found broken in the gear rechanien.

An entensive tecting progrcr has been condected to determine the cause of the high stecnflou icolaticn. It has been found that thic phenonenon occurs on a liPCI start with a relatively cool turbine. The icolation condition rpparently is not repeatable when the 190I is operated dail/, but has been repeated then the HPCI was idle for 68 hourc between operations.

Analycin of Occurrence HPCI failurc 'in itself procented no dcnger to cafe reactor operation cince other enginecred cafer;urd cysteus ucre available at thic time. The failure of FCV 73-2 to open rade it nececccry to bring the reactor to a cold chutdown condition for repairc.

Corrective Action The velve oncrator and rotor vere replaced end the valve returned to cervice after functionel testing. HFCI was natisfactorily tested on nuniliary coiler stecm and with reactor stern at 150 pcic and at rated pressure. Increasing the d/P trip point high enough to prevent cpurious isolation during HPCI ctartup  ;

trancients has been rejected an a renody of the EPCI icolation en startup. To t do co would recult in locc of cdecuate protection for the pipe.brea'c accident.

Until a colution is approved, operability of the Hf0I will be ensured by daily operation.

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