ML20084H568

AO BFAO-7437W:on 740602,switch 2 Failed to Operate at Tech Spec Setting of Greater than or Equal to 378 Inches Above Vessel Zero During Surveillance Testing.No Cause Stated. Switch Readjusted.Testing Frequency to Be Once Every 2 Wks

ML20084H568
Person / Time
Site:	Browns Ferry
Issue date:	06/12/1974
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084H572	List: ML20084H568 ML20084H574 ML20084H577
References
AO-BFAO-7437W, NUDOCS 8305040636
Download: ML20084H568 (2)

Text

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June 12, 1974 p * %'s

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IhA Mr. John F. O' Leary, Director 5k .,.7 j7@j Y/ }y7- $ I Directorate of Licensing g Y.h

Office of Regulation

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U.S. Atomic Ener6y Co mission Washington, DC 20545

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Dear Mr. O' Leary:

TEH!ESSEE VALLEY AUTHORITY - BROWS FERRY UUCLEAR PLtdiT UNIT 1 -

DOCKET HO. 50-259 - FACILITY OPERATING LICH!SE DPR ABNORMAL OCCURRE:!CE REPORT BFAO-7437W The enclosed report is to provide details concerning reactor vessel water level switch malfunction and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 This event occurred on Browns Ferry Kuclear Plent unit 1 on June 2, 1974.

Very truly yvurs, THEGSSEE VALLEY AUTHORITY

') - L jymr E. F. Thomas Director of Power Production

N Enclosure CC (Enclosure):

Mr. Norman C. Moseley, Director Region II Regulatory Operations Office, USAEC 230 Peachtrae street,ird., Suite 618 Atlanta, Georgia 30303

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8305040636 740612 PDR ADDCK 05000259 i (r 'h' S PDR  !. ,  ;

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ii ABFORMAL OCCURREIICE REPORT

• t Report No.: BFAO-7437U Report Date: June 12,-197b -

Occurrence Date: June 2, 1974 -

Facility: Browns Ferry Nuclear Plant unit 1 Identification of Ocet!rrence Reactor vessel water level switch malfunction.

Conditions Prior to Occurrence Reactor was in startup mode to continue startup testing.

Description of Occurrence During routine surveillance testing, LIS-3-583, switch No. 2, failed to operate at the technical specification setting of greater than or equal to 378 inches above vessel zero.

Analysis of Occurrence .

The. switch is part of the automatic depressurization system (ADS) initiation logic. The ADS is co= posed of two logies, each capabic of initiating the systc=,

Although LIS-3-583 was inoperable, level stdtches in the other logic were found to opcrc,tc corrcctly. Acrafet c, if tequ14cd, the AL3 wvuld imve 'veen lu1Lir. Led.

Corrective Action The switch is a nagnet-actuated proximity type. It was readjusted to onerate at the correct value and functionally tested. An accelerated testing frecuency of once ever/s 2 wecks has been initiated on the switch for the next 2 months. If the suitch tests satisfactorily during this period, the normal testing frequene'/

of once a month will be resumed.

Failure Data Yarway level indicating suitch, Model No. 4418EC, seriel No. 26693.

No previous failures have been experienced with this type of switch.

Stdtch Date Failure Corrective' Action

. LIS-3-58B 6/2/74 Setpoint drift Reset se^polat f

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