05000338/LER-1979-063-03, /03L-0 on 790501:during Startup Operation,Rods A06,F08,K08,H10,C07,C09,E05 & L11 Observed to Have 12-step Disagreement Between Various Rod Position Indications.Caused by Electronic Drift in RPI Circuitry.Rpis Recalibrated

/03L-0 on 790501:during Startup Operation,Rods A06,F08,K08,H10,C07,C09,E05 & L11 Observed to Have 12-step Disagreement Between Various Rod Position Indications.Caused by Electronic Drift in RPI Circuitry.Rpis Recalibrated

ML19263E207
Person / Time
Site:	North Anna
Issue date:	05/31/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19263E199	List: 05000338/LER-1979-059-03, /03L-0 on 790501:fire Protection Hose Stations in Auxiliary Bldg Were Inoperable for 10-h W/O Backup Sys of Firewatch Established.Caused by Isolation of Auxiliary Bldg for Maint Taking Longer than Initially Estimated 05000338/LER-1979-060-03, /03L-0 on 790502:during Routine Startup Operation, Axial Flux Difference Deviated Greater than 5% from Target. Caused by Power Increasing Too Rapidly During Startup Operation 05000338/LER-1979-063-03, /03L-0 on 790501:during Startup Operation,Rods A06,F08,K08,H10,C07,C09,E05 & L11 Observed to Have 12-step Disagreement Between Various Rod Position Indications.Caused by Electronic Drift in RPI Circuitry.Rpis Recalibrated ML19263E198
References
LER-79-063-03L, LER-79-63-3L, NUDOCS 7906050303
Download: ML19263E207 (2)

LER-1979-063, /03L-0 on 790501:during Startup Operation,Rods A06,F08,K08,H10,C07,C09,E05 & L11 Observed to Have 12-step Disagreement Between Various Rod Position Indications.Caused by Electronic Drift in RPI Circuitry.Rpis Recalibrated

Event date:
Report date:
3381979063R03 - NRC Website

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W. R. Cartwright pnoug:

NAME OF PREPARER

Virginia Electric and Power Company North Anna Power Station, Unit 1 Page 1 of 1 Dacket No:

50-333 Report No:

79-063/03L-0

Description of Event

During normal startup a greater than 12 step disagreement was noted for rods H06, F08, K08, H10, C07, C09, E05 and L11.

These rods were noted at various times during the startup and were corrected as they occurred.

All RPI's were returned to service within one hour.

Reactor power was less than 5% at the time of this event, therefore, the requirements of action statement A2 were met.

Probable Consequence of Occurrence Operability of the control rod position indication is required to determine 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 general public was not affected.

This event has no direct affect on Unit #2 since Unit #2 is not operational at this time.

Since identical RPI circuity exists for Unit #2, this problem of voltage drift may occur when Unit #2 does become operational.

Cause of Occurrence This cause of the indicator disagreement was due to the electronic drif t in the RPI circuity.

The exact cause was volta e drif t in the ass ociated signal condi-r tioning card.

Immediate Corrective Action

Recalibration and functional check were performed on rods H06, F08, K03, H10, C07, C 9, E05, and L11 individual rod position indicators.

Scheduled Corrective Action An engineering study of IRPI drif t is already in progress.

Action Taken To Prevent Recurrence No further action required at this time.

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