ML19270F830

LER 79-025/03L-0 on 790228:power Range Channel N42 Placed in Tripped Condition.Caused to Allow Replacement of Erratic Delta Flux Indicator.Indicator Replaced & Power Range Detector Returned to Svc

ML19270F830
Person / Time
Site:	North Anna
Issue date:	03/21/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19270F823	List: ML19270F822 ML19270F826 ML19270F830 ML19270F832
References
LER-79-025-03L, LER-79-25-3L, NUDOCS 7903270584
Download: ML19270F830 (2)

Text

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o 3 i tion to allow replacement of the N-42 Delta Flux indicator. Action Statement 2c of  ;

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44 3 36 3/ 43 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i O l Power range channel N-42 was placed in the tripoed condition to allow replacement of I

, i ;an erratically reading Delta Flux indicator. The indicator was replaced without I

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Attachment 1, page 1 of 1 Virginia Electric and Power Company North Anna Power Station, Unit #1 Docket No.: 50-338 Report No.: LER 79-025/03L-0 Description of Event:

During normal n ade 1 operation, channel N-42 delta flux indicator was noticed to be reading erratically. The other channels did not e xh ib i t the same behavior as channel N-42, therefore faulty indication was suspected. Although the indicator was still within calibration tolerances, replacement was desired. Power range channel N-42 was placed in a tripped condition and channel N-42 delta flux indicator was replaced within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

Probable Consequences of Event:

The delta flux indication associated with the power range detectors gives a continuous indication of flux shape within the core. Opera t ional requirements limit delta flux to certain values to insure hot channel factors are not exceeded. Although there is no reactor trip associated with the delta flux indication, it is still a safety related indication.

There are other methods for determining in core flux shapes in addition to three other delta flux indicator channels. Disabling one channel of power range instrumentation did not affect the safe operation of the plant or the health and safety of the general public.

Cause of Occurrence:

The cause of the erratic indication of channel N-42 delta flux indication was due to indicator failure.

Immediate Corrective Actions:

Channel N-42 delta flux indicator was replaced.

Subsequent Corrective Action:

No further action required.

Action Taken to Prevent Recurrences:

No further action required.

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