05000338/LER-1981-010-03, /03L-0:on 810211,w/unit in Mode 6,containment Purge & Exhaust Isolation Sys Was Rendered Inoperable When Power to MOV-HV-100B,D Was Lost.Caused by Fault on High Resistance Connection.Defective Parts Replaced

/03L-0:on 810211,w/unit in Mode 6,containment Purge & Exhaust Isolation Sys Was Rendered Inoperable When Power to MOV-HV-100B,D Was Lost.Caused by Fault on High Resistance Connection.Defective Parts Replaced

ML19345G246
Person / Time
Site:	North Anna
Issue date:	03/11/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19345G245	List: 05000338/LER-1981-010, Forwards LER 81-010/03L-0 05000338/LER-1981-010-03, /03L-0:on 810211,w/unit in Mode 6,containment Purge & Exhaust Isolation Sys Was Rendered Inoperable When Power to MOV-HV-100B,D Was Lost.Caused by Fault on High Resistance Connection.Defective Parts Replaced
References
LER-81-010-03L-02, LER-81-10-3L-2, NUDOCS 8103170444
Download: ML19345G246 (2)

LER-1981-010, /03L-0:on 810211,w/unit in Mode 6,containment Purge & Exhaust Isolation Sys Was Rendered Inoperable When Power to MOV-HV-100B,D Was Lost.Caused by Fault on High Resistance Connection.Defective Parts Replaced

Event date:
Report date:
3381981010R03 - NRC Website

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y U.S. NUCLEAR REGULATORY COMMISSION

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

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On February 11, 1981, with the unit in Mode 6, the Containment Purge and

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Exhaust Isolation System was rendered inoperable because power to MOV-HV-100B, /

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D was lost when the supply breaker feeding the motor control center for these /

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valves tripped because of a ground fault. Since the Purge and Exhaust

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penetrations (MOV-HV-100A, B, C, & D) were closed immediately, the health and /

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safety of the general public were not affected. This is contrary to T.S. 3.9. /

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9 and reportable pursuant to T.S. 6.9.1.9.b.

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SYSTEM

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ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRI' COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTLPER [A/ (18) LZ/ (19) [Z/ (20) /Z/ (21) /0/0/0/0/ (22) /Y/ (23) /N/ (24) [A/ (25) /K/1/8/2/ (26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

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A high resistance connection to a bus bar caused the fault which tripped open /

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the supply breaker to the motor control center. Defective parts of the MCC

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were replaced and the Containment Purge and Exhaust Isolation System was

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returned to service.

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FACILITY METHOD OF STATUS

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NA'1E OF PREPARER W.

R. CARTWRIGHT PHONE (703) 894-5151 810s179 g{g

Virginia Electric and Power Company North Anna Power Station, Unit #1 Attachment: Page 1 of 1 Docket No. 50-338 Report No. LER 80-010/03L-0

Description of Event

On February 11, 1981, with the unit in Mode 6, the containment Purge and Exhaust Isolation System was rendered inoperable due to a bad electrical connection on notor control center 1B1-2 causing the supply breaker to trip.

As a result, power to supply valve MOV-HV-100B and exhaust valve MOV-HV--100D was lost.

Probable Consequences of Occurrence Since the purge and exhaust penetrations (MOV-HV-100A, B, C & D) were immediately closed, the health and safety of the general public were not affected.

Cause of Event

A high resistance electrical connection at MCC IBI-2 caused an electrical fault which tripped open the motor control center supply breaker.

Immediate Corrective Action

Defective parts of the motor control center were replaced and the containment Purge and Exhaust Isolation System was returned to service.

Scheduled Corrective Action No corrective action is scheduled.

Actions Taken to Prevent Recurrence No action is-taken to prevent recurrence.

Generic Implications There are no generic implications.