05000338/LER-1979-028-03, /03L-0 on 790225:greater than 12-step Disagreement Noted Among Rod Position Indication,Computer Position Indication & Demand Signal Indication for Rod 9.Caused by Voltage Drift in Signal Conditioning Card

/03L-0 on 790225:greater than 12-step Disagreement Noted Among Rod Position Indication,Computer Position Indication & Demand Signal Indication for Rod 9.Caused by Voltage Drift in Signal Conditioning Card

ML19282C593
Person / Time
Site:	North Anna
Issue date:	03/26/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19282C591	List: 05000338/LER-1979-022-03, /03L-0 on 790227:power Supply to Post DBA H Recombiner Deenergized Rendering Recombiner Inoperable for 4-h.Caused by Deenergizing of Motor Control Center to Perform Voltage Measurements 05000338/LER-1979-028-03, /03L-0 on 790225:greater than 12-step Disagreement Noted Among Rod Position Indication,Computer Position Indication & Demand Signal Indication for Rod 9.Caused by Voltage Drift in Signal Conditioning Card ML19282C590
References
LER-79-028-03L, LER-79-28-3L, NUDOCS 7903300370
Download: ML19282C593 (2)

LER-1979-028, /03L-0 on 790225:greater than 12-step Disagreement Noted Among Rod Position Indication,Computer Position Indication & Demand Signal Indication for Rod 9.Caused by Voltage Drift in Signal Conditioning Card

Event date:
Report date:
3381979028R03 - NRC Website

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LICENSEE EVENT REPORT h CONTROL BLOCK: l l

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l l j (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6

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8 69 61 DOCK ET P. UMBER 63 69 EVENT DATE 74 25 REPORT DATE 83 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

' During Mode 2 operation, a greater than 12 sten disaareement was noted between rod i

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l position indication, computer position indication and demand signal indication for l

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1014ll rod N09. This was contrary to T.S. 3.1.3.2.

Reactor power was 4.05 durina this time I lO13l l and therefore action statement a.2 of T.S. 3.1.3.2 was satisfied.

This event is I

loisI reportable as per T.S. 6.9.1.9.b.

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS 27 i

O IThe cause for this indicator disaareomant was dun tn vn1tano drift in tha sinnal I

lilii lconditioning card.

Immediate corrective action was tn rocalibrato anef

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Lig l functional checks.

Both of which were done satisfactorily.

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NUMBER TYPE I t l 71 1010 l 0 l@l Z l@l N/A PERSONNE t iNau' RIES DESCRIPTION @

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8 9 11 12 80 LOSS OF OH DAMAGE TO FACILITY Q TYPE

DESCRIPTION

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8 9 10 W. R. Cartwright PHONE:

703-b90'blbl NAME OF PREPARER

Virginia Electric and Power Company North Anna Power Station Unit #1

Attachment:

Page 1 of 1 Docket No.

50-338 Report No.

LER 79-028/03L-0

Description of Event

During mode 2 eperation in preparation for shifting to mode 1 operation a greater than 12 step discrepancy was noted for rod position indication for rod N09.

This was contrary of T.S. 3.1.3.2.

Reactor power at the time of this discrepancy was 4% steady state.

Therefore the requirements of action statement a.2 were already met.

_ obable Consequences of Event:

Pr Operability of the control rod position indication is required to deter-mine control rod position and thereby ensure compliance with the control rod alignment and insertion limits.

Since reactor power was below 50% there was no effect on the safe operation of the plant and the health and safety of the genera: public was not endangered.

Cause of Occurrence The cause of the indicator disagreement was due to voltage drift in the signal conditioning card.

Immediate Corrective Action

Recalibration and functional checks were performed on Rod Position Indication for rod N09.

Both were performed satisfactorily.

Scheduled Corrective Action:

An engineering study of IRPI drift is already in progress.

A_ction Taken To Prevent Recurrence:

No further action required at this time.