ML19275A227

LER 79-100/03L-0:on 790903,during Steady State Operation, Greater than 12-step Disagreement Was Noted Between Rod Position Indicator D-10 & Group Demand Indication.Caused by Voltage Drift in Signal Conditioning Card

ML19275A227
Person / Time
Site:	North Anna
Issue date:	09/27/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19275A222	List: ML19275A221 ML19275A227 ML19275A231
References
LER-79-100-03L, LER-79-100-3L, NUDOCS 7910030347
Download: ML19275A227 (2)

Text

NRC FORM 66 U.S. NUCLE AR REGULATORY COMMISSloN CONTROL BLOCK: l l l f

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/ 8 ,J 63 DOCKET NUMB E R 6M 63 EVENT DATE EVENT DESCRIPTION AND PROBABLE CONSEQtlENCES h o 2 During steady state operation, a greater than 12 step disagreement was noted between i o 3 l rod position indicator D-10 and the group demand indication. This is contrary to l g) l T.S. 3.1.3.2. The rod position indication was restored 'rithin 8 hourr, as per l This event is reportable as per T.S. 6.9.1.9.b 4

[O s ! Action Statement a.2 of T.S. 3.1.3.2.

[5] The health and si.fety of the general public were not affected by this event. l O 1 l I

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i o l The cause of this event was a voltage drift in the signal conditioning card. l r, ,

Immediate corrective action was to recalibrate and to perform functional tests.

Further corrective actions have been determined and are presently being pursued. l

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i Virginta Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 1 Docke t No. 50-338 Report No. LER 79-100/03L-0 Description of Event:

During steady state operation, a greater than 12 step disagreement was noted between rod position indicator D-10 and the group demand indication. This is contrary to T.S. 3.1.3.2.

The rod position indication was restored within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> as per Action State-ment a.2 of T.S. 3.1.3.2.

This event is reportable as per T.S. 6.9.1.9.b. and is a generic problem with Unit #2. -

Probabic Consequences of Event:

Operability of the control rod position indication is required to determine control rod position and thereby ensure compliance with the control rod align-ment and insertion limits.

Since the control rod was not misaligned and the position indication was re-stored, there was no effect on the safe operation of the plant. As a result, a t no time was the health and safety of the general public affected.

Cause of Occurrence:

The cause of this event was a voltage drift in the signal conditioning card.

Immediate Corrective Action:

A recalibration and functional test was performed and the IRPI was returned to service.

Scheduled Corrective Action:

Results of an engineering study on IRPI drif t will be implemented.

Action Taken to Prevent Recurrences:

No further corrective action was required.

10/C2 L / -

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