05000285/LER-1980-027-03, /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

/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: 05000285/LER-1980-027, Forwards LER 80-027/03L-0 05000285/LER-1980-027-03, /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
References
LER-80-027-03L, LER-80-27-3L, NUDOCS 8011250474
Download: ML19345A954 (4)

LER-1980-027, /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

Event date:
Report date:
2851980027R03 - NRC Website

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secuencer timer testLtirer P4-6 ( Aux. P4 Pumo) on secuencer S1-2 f ailed to time out 1 taia!I 1, i a i I within the crescribed limit.

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LER No.80-027 Omaha Public Power District 4

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 not have prevented the complete anc proper loading of essential safe-t 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 Pumo) to be sequenced on arisen, the "A" channel prime signal sequencer 4

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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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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