05000338/LER-1979-038-03, /03L-0 on 790323:axial Flux Difference Outside 5% Target Band Due to Shutdown in Progress.Flux Difference Was Restored to Normal Range within Three Minutes by Boration

/03L-0 on 790323:axial Flux Difference Outside 5% Target Band Due to Shutdown in Progress.Flux Difference Was Restored to Normal Range within Three Minutes by Boration

ML19274E794
Person / Time
Site:	North Anna
Issue date:	04/18/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19274E780	List: 05000338/LER-1979-033, Forwards LER 79-033/03L-0,79-036/03L-0,79-037/03L-0 & 79-038/03L-0 05000338/LER-1979-033-03, /03L-0 on 790321: C Steam Generator Narrow Range Level Indicator LI-1496 Gave Readings w/20% Disagreement W/Two Other Channels.Caused by Steam Leak in One Sensing Line Isolation Valve 05000338/LER-1979-036-03, /03L-0 on 790320:control Room Emergency Ventilation Sys Charcoal Filters Failed 18-month Periodic Test.Caused by Filters Reduced Absorption Capabilities. Filters Have Been Replaced 05000338/LER-1979-037-03, /03L-0 on 790323:unidentified Reactor Coolant Leak Greater than One Gallon Per Minute Detected.Caused by Packing Gland Leak in Pressure Control Valve.Valve Was Repaired & Normal Operation Resumed 05000338/LER-1979-038-03, /03L-0 on 790323:axial Flux Difference Outside 5% Target Band Due to Shutdown in Progress.Flux Difference Was Restored to Normal Range within Three Minutes by Boration
References
LER-79-038-03L, LER-79-38-3L, NUDOCS 7904240421
Download: ML19274E794 (2)

LER-1979-038, /03L-0 on 790323:axial Flux Difference Outside 5% Target Band Due to Shutdown in Progress.Flux Difference Was Restored to Normal Range within Three Minutes by Boration

Event date:
Report date:
3381979038R03 - NRC Website

text

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tVENT DATE 74 lb HEPOH1 DATE 80 EVENT DESCRIPTION AND PROH ABLE CONSEQUENCES h l On 3-23-79 during a shift from Mode I to Mode II operation, the axial flux difference i o 2 l was outside the + 5% target band established by T.S. 3.2.1.

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NAME OF PREPAHER PHONE:

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

Attachment:

Page 1 of 1 Docket No.

50-338 Report No.

79-38/03L-0

Description of Event

On 3-23-79 during a shift from Mode I to Mode II' operation, the axial flux difference (AFD) was noticed to be outside t:1e 1 5% target band established by T.S. 3.2.1.

Actions were immediately taken to restore the AFD within its band. The total time the AFD was out of its band was 3 minutes.

Probable Consequence of Occurrence Axial flux indication is used to monitor in core flux shapes and to ensure abnormal flux shapes do not occur which could lead to exceeding hot channel factors.

If AFD is outside its target band, operational restrictions are placed on plant operations. None of these operating restrictions were exceeded, therefore the health and safety of the general public were not affected.

Cause

The cause for AFD exceeding its target band limits was the reactor shutdown that was in progress.

Immediate Corrective Actions

Returned AFD to within its, target band within 3 minutes by boration.

Scheduled Corrective Actions No further action required.

Action Taken to Prevent Recurrence No action required.

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