ML20085M921

AO BFAO-7333W:on 731108,during Accelerated Surveillance Testing,Reactor Protection Sys Water Level Switches LIS-3-203B & C Malfunctioned.Caused by Setpoint Drift. Switches Recalibr

ML20085M921
Person / Time
Site:	Browns Ferry
Issue date:	11/16/1973
From:	Eric Thomas TENNESSEE VALLEY AUTHORITY
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20085M925	List: ML20085M921 ML20085M927 ML20085M931
References
AO-BFAO-7333W, NUDOCS 8311090459
Download: ML20085M921 (3)

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TENNESSEE VAL Y AUTHORITY M CHA'TTANDOGA, TENNESSEE 5 lc 37401 L Jbm

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e: f Mr. John F. O'Imary, Director g f Directorate of Licensing g Office of Regulation 4 ,

U.S. Atomic Energy Cc= mission w~ ~ ~

Washington, DC 20545

Dear Mr. O'Icary:

TEIRIESSEE VALIZY AUTHORITY - BROUNS FERRY NUCIEAR PLANT UNIT 1 -

DOCKET IIO. 50-259 - F1.CILITY OPEP.ATING LICENSE DPR ABNORMAL OCCURRENCE REPORT BFAO-7333u The enclosed report is to provide details concerning a reactor water level switch malfunction which occurred on Erowns Ferry Nuclear Plant unit 1 on I:avember 8,1973, and is submitted in accordance with Appendix A to Regulatory Guide 1.16, Revision 1, October 1973 Very truly youro, TE'CTESSEE VALLEY AUTHORITY

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

Mr. Homan C. Moseley, Director Region II Regulatory Operationc Office, USAEC 230 Peachtree Street, IN.

Atlanta, Georgia 30303 0

8311090459 731116

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g o o ABNDINAL OCCURRENCE REPORT Report No.--EFAO-7333W Report Date--November 16, 1973 Occurrence Date--November 0,1973 Facility--Browns Ferry Nuclear Plant unit 1 Identification of Occurrence -

Unit 1 reactor protection system reactor water level switch malfunction.

Conditions Prior to Occurrence Reactor at 30-percent power, 300 MWe, during startup test program.

Description of Occurrence During accelerated surveillance testing on November 8,1973, reactor water level switches LIS-3-2033 and C vere found to operate outside the technical specifi-cation setpoint of 538 inches above vessel zero as specified in Table 3 1.A.

The switches operated at 533 inches and 537 inches, respectively.

Analysis of Occurrence These level switches are arranged in a one out of two taken twice logic in the reactor protection system. The other two channels were immediately' tested and-found to operate satisfactorily. If required, the RPS would have.perfomed its intended function.

Corrective Action The switches vere recalibrated and functionally tested several . times -to verify.

repeatability. New locking plate assemblies will be installed pending their

. receipt which is expected within two weeks. An accelerated testing frequency of once a week has been initiated for all four switches. This test frequency

~, vill also apply to the switches after locking devices are. installed until three consecutive tests prove satisfactory. The testing frequency will then be increased to biveckly'and the original test schedule of once a month. vill.be.

resumed after three consecutive tests have been satisfactorily perfomed on' the biveekly frequency..

9 Failure Data-

. )Barton.Model288 differential preasu m indicating. switch. . .

Serial Nos.:~ LIS-3-203B--288A-9959~ -:

. 'LI8-3-203C--288A-9960 ,

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7. . . - O 2-O Switch Date Failure Corrective Action operated outside tech Reset switch to setpoint US-3-203B 10/9/73

- spec limit operated outside tech Reset switch'to setpoint us-3-203c 10/9/73 ,

spec limit Cperated outside tech Reset Ewitch to setpoint -

us-3-203B n/8/73 spec limit -

Operated outside tech Reset switch to setpoint US-3-203c n/8/73 spec limit .

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