05000339/LER-1981-038-03, /03L-0:on 810505,during Mode 1 Operation,Channel III Feedwater Flow Indication for Loop 2 Failed High.Caused by Failure of Loop Multiplier/Divider/Square Root Card.Card Replaced & Channel Recalibr & Returned to Svc

/03L-0:on 810505,during Mode 1 Operation,Channel III Feedwater Flow Indication for Loop 2 Failed High.Caused by Failure of Loop Multiplier/Divider/Square Root Card.Card Replaced & Channel Recalibr & Returned to Svc

ML20004D602
Person / Time
Site:	North Anna
Issue date:	06/03/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20004D595	List: 05000339/LER-1981-038, Forwards LER 81-038/03L-0 05000339/LER-1981-038-03, /03L-0:on 810505,during Mode 1 Operation,Channel III Feedwater Flow Indication for Loop 2 Failed High.Caused by Failure of Loop Multiplier/Divider/Square Root Card.Card Replaced & Channel Recalibr & Returned to Svc
References
LER-81-038-03L, LER-81-38-3L, NUDOCS 8106090570
Download: ML20004D602 (1)

LER-1981-038, /03L-0:on 810505,during Mode 1 Operation,Channel III Feedwater Flow Indication for Loop 2 Failed High.Caused by Failure of Loop Multiplier/Divider/Square Root Card.Card Replaced & Channel Recalibr & Returned to Svc

Event date:
Report date:
3391981038R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BL0CK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On May 5, 1981, during Mode 1 operation, Channel III feedwater flow indication /

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for Loop 2 failed high. This condition would have prevented the channel from /

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generating a reactor trip signal on a steam flow / feed flow mismatch (FS>FW)

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coincident with low steam generator level. The affected steam flow > feed flow /

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reactor trip bistable was placed in that tripped conditien in I hour by placing /

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the feed flow channel in " test". Therefore, the health and safety of the gener-/

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al public were not affected.This event is reportable pursuant to T.S.6.9.1.9.b./

SYSTEM

CAUSE

CAUSE COMP.

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CODE TYPE NO.

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CAUSE' DESCRIPTION aND CORRECTIVE ACTIONS (27)

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The feed flow channel failed high due to failure of the loop multiplier /

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divider / square root card. The defective NMD card was replaced and the channel /

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was satisfactorily recalibrated and returned to service.

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FACILITY METHOD OF DIS M RY DESCR M M (32)

STATUS

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OPERATOR OBSERVATION

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NA ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36) l

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l PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39) l

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LOSS OF OR DAMAGE TO FACILITY (

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TIPE

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PUBLICITY l-ISSUED DESCRIPTION (45)

NRC USE ONLY

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NAME OF PREPARER W. R. CARTWRIGHT PdCN (703) 894-5151 0

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Decket No. 50-339 Report No. LER 81-038/03L-0

Description of Event

On May 5,1981, while operating at 100% power, it was observed that the Channel III indication for Loop 2 feedwater flow had failed high. This condition would have prevented a reactor trip signal from being generated by the channel on a steam flow / feed flow mismatch (steam flow > feed flow) coincident with low steam generator level.

This event is contrary to T.S. 3.3.1.1 and reportable pursuant to T.S.

6.9.1.9.b.

Probable Consequences of Occurrence The consequences of this event were limited because the steam flow >

feed flow reactor trip bistable was placed in the tripped condition within I hour in accordance with the Action Statement of T.S. 3.3.1.1 and channel IV for Loop 2 feedwater flow remained operable. As a result, the health and safety of the general public were not affected.

Cause of Event

The feed flow channel failed high due to failure of the multiplier /

divider / square root card (NMD card) in the loop circuitry.

Immediate Corrective Action

i The defective NMD card was removed and replaced with a new card.

The channel was then satisfactorily recalibrated per procedure and returned to service.

Scheduled Corrective Action No scheduled corrective action is required.

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Actions Taken to Prevent Recurrence l

No further actions are required.

Generic Implications There are no generic implications associated with this occurrence.

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