ML20085G962

AO BFAO-50-259/7453W:on 741007,loss of Position Indication Discovered in Suppression Chamber to Drywell Vacuum Breakers.Caused by Ground on Common Side of Position Indicating Lights for Valve FCV-64-28M

ML20085G962
Person / Time
Site:	Browns Ferry
Issue date:	10/17/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Case E US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085G957	List: ML20085G956 ML20085G962 ML20085G969
References
NUDOCS 8308290559
Download: ML20085G962 (3)

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, 'ul T;'ENNEElG3G VALLL . AU T H C A !TY " "~2 0 ' ' ~\;

Ci-iATTANCCGA, TENNESSE5 ,

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- l October 17, 1974 G, h/ s SEF 7 9/m 1. .m; b

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Mr. Edson G. Case .g 0ON4 /S/,j x ["l ' . ,,

d Acting Director of Licensing L: ,~ t et sx Office of Regulation ' '

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U.S. Atonic Energy Co=11ssion 1z. k ..

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Dear Fr. Case:

TEmiESSEE VALLEY AUTEORITY - BR0iGS FERRY UUCLEAR PLANT UNIT 1 -

DOCKET ';0. 50-259 - FACILITY OPERATII!G LICENSE DPR ABUCTSAI, 00CUF23CE REPORT BFAO-50-259/7453W The enclosed report is to provide details concerning loss of position indication on unit 1 surpression cha.nber to drpell vacuum breakcra and is submitted in accorda: ice with Appendix A to Regulatory Ouide 1.16, Revision 1, October 1973 This event occurred on B_ owns Ferry Huelcar Plant unit 1 on October 7, 1974.

Very tru 4 yours, TE'i1CSSEE VALLEY AUTEORITY

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E. F. Thomas Director of Power Production Enclosure CC (Enclosure):

Mr. Hornan C. Moceley, Director Region II Regulatory Operations Office, USAEC 230 reachtree Street, nu., Suite 818 Atlanta, Georgia 30303 8308290559 750117 1 {'i s'o / 7 PDR ADOCK 05000259 PDR S

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. . ABNORVAL OCCURRENCE REPORT ,

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• Report Number  : BEAO-50-259/7453W  !

Report Date  : October 17, 1974  !

Occurrence Date: October 7, 1974 l Facilty  : Brownc Ferry Nuclear plant Unit 1 i i

k Identificaticn of Occurrence Loss of pocition indication on unit 1 suppression chamber to drywell vacuum breakers.

Conditions Prior to Occurrence The reactor vac in rcutine startup operation at 34-percent power. pressure relief valves PCV-1-19 and ICV-1-23 had been operated manually a chort time ,

previously because of suspected seat leakage.

Description of Occurrence  :

The pocition indicating lights were loct on all twelve suppression chamber to drywell vacuum breakers FCV-64-28A thrcugh FCV-64-28M. Maintenance perscnnel were alerted and fcund that the fuse was blown in the indicating light circuit.

r Designaticn of Arparent Cause of Occurrence e

The failure was caused by a grcund on the commen cide of the position indicating lights for FCV-64-2SM which cauced the fuse supplying power to all 12 vacuum breaker position indicating lights to fail. The ground may have been caused by the chock or moisture created by cperaticn of relief valves ICV-1-19 and PCV-1-23 The exact cause cannot be determined until suppression chamber entry can be cade.

8 Analysis of Occurrence At the time the pcwer supply to the lighting circuit was lost, the vacuum breakers were in their proper closed pocition. The pocition of the dice on the suppression chamber to drywell vacuum breakers cannot be accertained by the operator without indicating lights. Therefore, as required by technical cpecifications, an >

orderly chutdown was started. Circuit continuity checks were performed while shutdown was in progrecc, and these checks showed that the valves were closed.

During the reactor descencien, efforts uere continacd to restore power to the lighting circuit. The pocition indicating lights for all vacuum breakers except FCV-64-28M were rectored, and these lights indicated the valves were closed. A "

temporary light uns installed using a ceparate power cource for FCV-64-28M which verified complete clocure.

The vacuum breakers were in a proper position and would have perforned their intended function. The failure of the lighting circuit did not cause damage to any other systens, componenta, or structures or create any adverse effect on the public health and cafety.

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Corrective Action Perranent pcVer was rectored to all ker indicating lights except FCV 64-28M. A temporary indicatinc 1 ch w~ n ted in series with a separate rover courca and th f P i itch for FCV-64-28M.

A ='k nci e the Thevacu'hbreakervalvepositi ind cupprecclcn enamber vill be ins ected h PP O , hamber entry can be

',fnen the cause of the r A -

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taken to prevent repetition o t occu en ado 3 o e rren e Failure Data

+he Grouna hac been determined, Failure data Will be reported when the cause O'*

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