05000338/LER-1979-116-03, /03L-0:on 790913,during Steady State Power,Two Disagreements Noted Between Individual Rad Position Indicator & Group Demand Counter.Caused by Instrument Drift. Indicators Recalibr & Tested Satisfactorily

/03L-0:on 790913,during Steady State Power,Two Disagreements Noted Between Individual Rad Position Indicator & Group Demand Counter.Caused by Instrument Drift. Indicators Recalibr & Tested Satisfactorily

ML19209B966
Person / Time
Site:	North Anna
Issue date:	10/08/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19209B965	List: 05000338/LER-1979-116, Forwards LER 79-116/03L-0 05000338/LER-1979-116-03, /03L-0:on 790913,during Steady State Power,Two Disagreements Noted Between Individual Rad Position Indicator & Group Demand Counter.Caused by Instrument Drift. Indicators Recalibr & Tested Satisfactorily
References
LER-79-116-03L, LER-79-116-3L, NUDOCS 7910110330
Download: ML19209B966 (2)

LER-1979-116, /03L-0:on 790913,during Steady State Power,Two Disagreements Noted Between Individual Rad Position Indicator & Group Demand Counter.Caused by Instrument Drift. Indicators Recalibr & Tested Satisfactorily

Event date:
Report date:
3381979116R03 - NRC Website

text

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8 60 61 DOCKET NUV3EH 68 63 EVENT DATE 14 75 REPOR T D AT E 80 EVENT DESCRIPTION AND PRO 3ABLE CONSEQUENCES O'o lDuring steady state operation on 9/13/79, Individual Rod Parition Indicator H02 o

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disagreed greater than 12 steps from the group demand counter. On 9/14/79, IRPI B08 g

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disagreed greater than 12 steps from the group demand counter. These events are l

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gcontrary to T.S. 3.1.3.2.

The IRPI's were returned to service within the time limits ;

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j of the appropriate a tion statement. This event is reportable as per T.S. 6.9.1.9.b.

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a gThese events are generic to Westinghouse Analog IRPI systems.

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T2 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS IThe cause of the IRPI disagreements was instrument drift.

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Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment: Page 1 of 1 Docket No. 50-338 Report No. LER 79-ll6/03L-0

Description of Event

During steady state operation at 34% power on 9/13/79, the Individual Rod Position Indicator H02 disagreed greater than 12 steps from the group demand counter. On 9/14/79, IRPI B08 indicated greater than 12 steps from its group demand counter.

These events are contrary to T.S. 3.1.3.2.

The IRPI's were returned to service within the time allowance of the Actic.: Statement.

These events are reportable as per T.S. 6.9.1.9.b.

and are generic to Westinghouse analog IRPI systems.

Frobable Consequences of Occurrence Operability of the control rod position indicators is required to determine control rod positions and ".areby ensure compliance with the control rod alignment and insertion limits.

Since '.he control rods were not misaligned and the IRPI's were returned to service as per the Action Statement, the safe operation of the unit was not affected.

As a result, at no time was the health and safety of the public affected.

Cause of the Event

The IRPI disagreements were the result of instrument drift.

Immediate Corrective Action

The IRPI's were recalibrated and functional tests were performed to ensure operability.

Scheduled Corrective Action Results of an Engineering Study on IRPI drift will be implemented.

Actions Taken To Prevent Recurrence No further action is required.

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