ML19275A142

LER 79-015/03X-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

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: ML19275A140 ML19275A142
References
LER-79-015-03X, LER-79-15-3X, NUDOCS 7908310444
Download: ML19275A142 (1)

Text

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NRC FQflM 366' U.S. NUCLEAR REGULATORY COMMISSION (7pl UPDATE REPORT PREVIOUS _RE_P_0ET_DATE__ JUNE 23, 1979

", LWCW3tt CV CW I M tt'U M I (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

CONTROL BLOCK:

1 l l l l l lh 6

o 1 lNlE l C l P l R l 141 l@l 15 0 l 0 l - l 0 lLICENSE l 0 l - l 0 0 l 025l@l264 l 1LICENSE 0 l 0NUM.iER l 1 TYPE 1 1l@l JO l

57 CAT 58 I@

7 8 9 LICENSEE CODE CCN'T 0 1 5ouRC I60L l@LOi s l 0DOCKETl 0 lNUMBER 0 l 2 i 9 l 868 @l69 01512 5 7 I8 74@ l0 EVENTI DATE 75 0l . 01ATE 7l ol@

l AlREPORT 80 7 8 61 .

EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h o 2 lAf ter reactor scrammed on APRM Hi upscale, breaker lAS failed to close automaticallv. I m lThe breaker was then closed by its control switch. Breaker lAS ties 4160V bus lA to l o 4 Ithe startup transformer when the generator trips. Breaker 1FA failed to trip automatic-l o s lally and when its control switch was operated to TRIP. This breaker is one of two brea l-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 o 8 preaker IFA failure to trip is repetitive (79-8) . 80 I

7 8 9 SYSTEM CAUSE CAUSE COMP. VALV E CODE CODE SUSCODE COMPONENT CODE SUBCODE SUSCODE 7

o 9 8

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9 10 11 12 13 18 19 E @ W@ 20 SEQUENTIAL OCCURRENCE REPORT REVISION EVENTYEAR REPORT NO. CODE TYPE NO.

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37 41 42 l@ J@ lGl0l8l0l@

43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i o l Breaker lAS apparently failed to close because of improper operation of switch 52 in 1

["i"TTl breaker 1AN. GE has been requested to evaluate. Switch < ontacts were cleaned ed :estell

, 2 l satisfactorily. Breaker 1FA failed to trip because misalignment of the trip co'1 and I i 3 l the trip armature. Breakers are GE Magna Blasr Type AMH 4.76-250. l i 4 I l

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ST * % POWE R OTHER STATUS Dis O RY DISCOVERY DESCRIPTION y l Gl@ l010 l0 l@l NA l lAl@l Operator Observation l ACTIVITY CO TENT RELEASEO OF MELEASE AMOUNT OF ACTIVITY LOCATION OF RELEASE NA 7

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PERSONNEL EXPOSURES NUMBE R TYPE OESCRIPTION i 7 1010101@l Zl@l NA l 8

' PER$cNNd%u'4ES NuMeEa DESCRIPTION @ / O 3;z . ,9 l i NA l 7

4 8 9 10101 Ol@l12 11 80 LOSS OF OR OAMAGE TO FACILITY h TYPE D E SC RIP TION  %/

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F is '3 to ehr PHCNE:

402-825-3811 NAME OF PAEPARER