05000339/LER-1981-035-03, /03L-0:on 810423,RCS Subcooling Monitor Channel a Declared Inoperable.Caused by Erroneous Readings Due to Failure of Personnel to Return Monitor to Svc After Overpressurization Protection Instrumentation Testing

/03L-0:on 810423,RCS Subcooling Monitor Channel a Declared Inoperable.Caused by Erroneous Readings Due to Failure of Personnel to Return Monitor to Svc After Overpressurization Protection Instrumentation Testing

ML19345H393
Person / Time
Site:	North Anna
Issue date:	05/15/1981
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345H392	List: 05000339/LER-1981-035, Forwards LER 81-035/03L-0 05000339/LER-1981-035-03, /03L-0:on 810423,RCS Subcooling Monitor Channel a Declared Inoperable.Caused by Erroneous Readings Due to Failure of Personnel to Return Monitor to Svc After Overpressurization Protection Instrumentation Testing
References
LER-81-035-03L, LER-81-35-3L, NUDOCS 8105200234
Download: ML19345H393 (2)

LER-1981-035, /03L-0:on 810423,RCS Subcooling Monitor Channel a Declared Inoperable.Caused by Erroneous Readings Due to Failure of Personnel to Return Monitor to Svc After Overpressurization Protection Instrumentation Testing

Event date:
Report date:
3391981035R03 - NRC Website

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U.S. NUCLEAR REGULATORY CO.TfISSION LICENSEE EVENT REPORT O-CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

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DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

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On April 23, 1981, during Mode 1 operation, the Channel A Reactor Coolant Sys- /

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tem subcooling monitor was declared inoperable after erroneous readings were

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observed. Because the redundant Channel B core cooling monitor remained

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operable and the A monitor was restored to operable status within 7 days, the /

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public health and safety were not affected. This event is reportable pursuant /

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to T.S. 6.9.1.9.b.

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SYSTEM

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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The subcooling monitor malfunction was caused by failure of test persennel to /

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properly return the monitor to service earlier in the day upon completion of

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overpressurization protection instrumentation testing (2-PT-44.4.1). The

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monitor was satisfactorily returned to service by setting sensor defeat

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- witches to their proper position as applicable.

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FACILITY METHOD OF STATUS

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OPERATOR OBSERVATION

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8105200 W

Virginia Electric and Power Company North Anna Power Station, Unit #2 Attachment: Page 1 of 1 Docket No. 50-339 Report No. LER 81-035/03L-0

Description of Event

On April 23, 1981, during Mode 1 operation at 100% power, the Channel A Reactor Coolant System subcooling monitor was observed to be malfunctioning and was declared inoperable. This event'is contrary.

to T.S. 3.3.3.6, which requires two subcooling margin monitors to be operable in Modes 1, 2 and 3, and is reportable pursuant to T.S.

6.9.1.9.b.

Probable Consequences of Occurrence The purpose of the Reactor Coolant Subcooling Monitoring System is to provide continuous enalog indication of margin to saturation from RCS temperature and pressure inputs. Because the Channel B subcooling monitor remained operable to provide the required indication and the A monitor was restored to operable status within 7 days, the health and safety of the general public were not affected by the event.

Cause of Event

The subcooling monitor malfunction resulted when test personnel failed to properly return the monitor to service after overpressurization protection instrumentation testing (2-PT-44.4.1) was completed earlier in the day.

Immediate Corrective Action

The A core cooling monitor was satisfactorily returned to service by placing sensor defeat switches in their proper position as i

applicable.

Scheduled Corrective Action No scheduled corrective action is required.

Actions Taken to Prevent Recurrence Personnel involved were reinstructed on the importance of returning systems to normal conditions fcllowing satisfactory testing.

Generic Implications There are no generic implications associated with this event.