05000321/LER-1981-072-03, /03L-0:on 810707,instrument Root Valve B21-F500 for Low Condenser Vacuum Switches Had Been Isolated Causing Instruments to Trip.Cause Unknown.Valve Returned to Correct Position.Root Valves Locked Open

/03L-0:on 810707,instrument Root Valve B21-F500 for Low Condenser Vacuum Switches Had Been Isolated Causing Instruments to Trip.Cause Unknown.Valve Returned to Correct Position.Root Valves Locked Open

ML20009F454
Person / Time
Site:	Hatch
Issue date:	07/21/1981
From:	Coggin C GEORGIA POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML20009F451	List: 05000321/LER-1981-072, Forwards LER 81-072/03L-0 05000321/LER-1981-072-03, /03L-0:on 810707,instrument Root Valve B21-F500 for Low Condenser Vacuum Switches Had Been Isolated Causing Instruments to Trip.Cause Unknown.Valve Returned to Correct Position.Root Valves Locked Open
References
LER-81-072-03L, LER-81-72-3L, NUDOCS 8107310170
Download: ML20009F454 (2)

LER-1981-072, /03L-0:on 810707,instrument Root Valve B21-F500 for Low Condenser Vacuum Switches Had Been Isolated Causing Instruments to Trip.Cause Unknown.Valve Returned to Correct Position.Root Valves Locked Open

Event date:
Report date:
3211981072R03 - NRC Website

text

l NRC FORM 366 U5 S. NUCLEAR REGULATORY COMMISSION

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LICENSEE EVENT REPORT e

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60 61 OOCKiT NUMBER 68 69 EVENT DATE 14 75 REPORT D ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Ol2l lFollowing a reactor scram it was discovered that the instrument root j

[O i3 i l valve (B21-F500) for the low condenser vacuum switches (821-N056A,8) had i 10141 l bpon isolated. therphy. causing the instruments to be in the trin condi l lo151Itina.

Thorp were no effects uoon the oublic health and safety due to

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33 34 35 36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h lilolIThe exact cause of valve misposition is not known.

Upon discovery, the l [i ti j l valve was returned to the correct position.

All low condenser vacuum I

ii#2i iroot valves have been locked open in a manner to prevent recurrence of I

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O LER #:

50-321/1981-072 Licensee:

Georgia Power Company Facility Name:

Edwin I. Hatch Docket #:

50-321

Narrative

Report for LER 50-321/1981-072 1

Following a Rx scram it was discovered that the instrument root valve (B21-F500) for the low condenser vacuum switches (B21-N056AGB) had been isolated, thereby, causing the instrum-ents to be in the trip condition.

This, in fa't, had caused a c

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isolation and subsequently precipitated the reactor geram.

Redundant switches were available and operable.

The exact cause of the valve misposition is not known.

- In order to prevent recurrence the isolation valvesefor all low conden-ser vacuum switches on HNP-152 have been locked open in a

'aanner to prevent closing the valves without first removing the locking mechanism.

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