05000298/LER-1979-015-03, /03X-1 on 790525:breaker 1AS Failed to Close Automatically After Reactor Scrammed.Caused by Improper Operations of Switch 52 in Breaker 1AN.Breaker 1FA Failed to Trip.Caused by Misaligned Trip Coil & Armature

/03X-1 on 790525:breaker 1AS Failed to Close Automatically After Reactor Scrammed.Caused by Improper Operations of Switch 52 in Breaker 1AN.Breaker 1FA Failed to Trip.Caused by Misaligned Trip Coil & Armature

ML19275A142
Person / Time
Site:	Cooper
Issue date:	08/01/1979
From:	Bednar L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19275A141	List: 05000298/LER-1979-015, Forwards LER 79-015/03X-1 05000298/LER-1979-015-03, /03X-1 on 790525:breaker 1AS Failed to Close Automatically After Reactor Scrammed.Caused by Improper Operations of Switch 52 in Breaker 1AN.Breaker 1FA Failed to Trip.Caused by Misaligned Trip Coil & Armature
References
LER-79-015-03X, LER-79-15-3X, NUDOCS 7908310444
Download: ML19275A142 (1)

LER-1979-015, /03X-1 on 790525:breaker 1AS Failed to Close Automatically After Reactor Scrammed.Caused by Improper Operations of Switch 52 in Breaker 1AN.Breaker 1FA Failed to Trip.Caused by Misaligned Trip Coil & Armature

Event date:
Report date:
2981979015R03 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION NRC FQflM 366 (7pl UPDATE REPORT PREVIOUS _RE_P_0ET_DATE__ JUNE 23, 1979 LWCW3tt CV CW I M tt'U M I CONTROL BLOCK:

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8 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT 0 ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lAf ter reactor scrammed on APRM Hi upscale, breaker lAS failed to close automaticallv.

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2 m lThe breaker was then closed by its control switch. Breaker lAS ties 4160V bus lA to l

Ithe startup transformer when the generator trips. Breaker 1FA failed to trip automatic-l o

4 lally and when its control switch was operated to TRIP. This breaker is one of two brea l-o s

10 is I lakers connected in series which ties 4160V bus IF to bus 1A.This occurrence presented l 0

7 ln0 adverse Consequences to public health and safety. Redundant systems were available. I preaker IFA failure to trip is repetitive (79-8).

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33 34 35 36 37 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l Breaker lAS apparently failed to close because of improper operation of switch 52 in 1 i

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["i"TTl breaker 1AN. GE has been requested to evaluate. Switch < ontacts were cleaned ed :estell l satisfactorily. Breaker 1FA failed to trip because misalignment of the trip co'1 and I

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3 l the trip armature. Breakers are GE Magna Blasr Type AMH 4.76-250.

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