ML19345A954

LER 80-027/03L-0:on 801027,during Monthly Ac Sequencer Timer Test,Timer FW-6 on Sequencer S1-2 Failed to Time Out within Prescribed Limit.Caused by Sticky Operating Mechanism.Timer Replaced W/Spare

ML19345A954
Person / Time
Site:	Fort Calhoun
Issue date:	11/03/1980
From:	Mueller R OMAHA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19345A949	List: ML19345A948 ML19345A954
References
LER-80-027-03L, LER-80-27-3L, NUDOCS 8011250474
Download: ML19345A954 (4)

Text

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• SQ 63 CCCK ET NvV9ga EVENT OESCRIPTtCN ANo PnC9ABLE CONSECUENCES h la 6 2i ! Ourino the cerformance of Surveillance Test ST-ESF-5. Section .1 (the monthlv 3C 1 taia!I secuencer timer testLtirer P4-6 ( Aux. P4 Pumo) on secuencer S1-2 f ailed to time out 1 1, i a i I within the crescribed limit. Durino the time of the failure, the DC secuencer cir- 1 I,i3i i cuitry which activates P4-6 as well as the AC and DC secuencer circuitrv actuatino i I

I a is 1 I the redundant Aux. Feedwater Puro (P4-10) were found to be coeratinc as desianed.

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LER No.80-027 4

Omaha Public Power District Fort Calhoun Station Unit No.1 Docket No. 0500028S

! Attacnment No. I Safety Analysis i The Fort Calhoun Station Unit No.1 is so designed that no single j . failure can prevent the safe shutdown of the plant, if required. The

failure of tt:e FW-6 timer relay associated with AC sequencer 51-2 would t

not have prevented the complete anc proper loading of essential safe-

j. guards equipment should the need have arisen.

Prior to starting ST-ESF-5, prime signal sequencers Sl-1 and S2-1

. were operable and in auto standby. (Sl-1 and $2-1 are the DC powered

sequencers fed from the "A" and "B" engineered safeguards channels re-spectively). The derived signal sequencers 51-2 and $2-2 were then separately bypassed as per ST-ESF-5 to test their Bliss Eagle timing relays. (Sl-2 and S2-2 are the AC paered sequencers fed from "A" and "B" channels respectively). Had the need for FW-5 (Auxiliary Feedwater 4

Pumo) to be sequenced on arisen, the "A" channel prime signal sequencer Sl-1) would have performed the desired function. In additien, the "B" channel sequencer $2-1 (prime) woulc have sequencec on the redundant Auxiliary FW pumo (FW-10) had it been called upon to do so.

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LER No.80-027 Omaha Public Power District Fort Calhoun Station Unit No.1 Cocket No. 05000285 Attachment No. 2 Corrective Action The Bliss Eagle timer in question was replaced with an identical scare which was, in turn, satisfactorily tested per ST-ESF-5 (F.1).

The A-C sequencer timers of sequencers Sl-2 and 52-2 will continue to be exercised and operability verified on a monthly basis per sur-veillance test ST-ESF-5.

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I LER No.80-027 Omaha Public Power District Fort Calhoun Station Unit No.1 Docket No. 05000285 Attachment No. 3 Failure Data This is the eleventh failure of a Bliss Eagle Timer. Previous failures were reported per:

Abnormal Occurrence 75-1 Abnormal Occurrence 75-13 Abnormal Occurrence 75-16 LER 76-21 LER 77-9 LER 77-18 LER 77-25 LER 78-016 LER 78-027 LER 78-032

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