05000298/LER-1979-008-03, /03L-0 on 790420:breaker 1FA Failed to Trip When Control Switch Operated to Trip.Caused by Failure of Auxiliary Switch Contact Mounted Inside Breaker 1FA to Make Proper Electrical Contact.Breaker Inspected & Cleaned

/03L-0 on 790420:breaker 1FA Failed to Trip When Control Switch Operated to Trip.Caused by Failure of Auxiliary Switch Contact Mounted Inside Breaker 1FA to Make Proper Electrical Contact.Breaker Inspected & Cleaned

ML19274F042
Person / Time
Site:	Cooper
Issue date:	05/18/1979
From:	Bednar L NEBRASKA PUBLIC POWER DISTRICT
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
Shared Package
ML19274F041	List: 05000298/LER-1979-008, Forwards LER 79-008/03L-0 05000298/LER-1979-008-03, /03L-0 on 790420:breaker 1FA Failed to Trip When Control Switch Operated to Trip.Caused by Failure of Auxiliary Switch Contact Mounted Inside Breaker 1FA to Make Proper Electrical Contact.Breaker Inspected & Cleaned
References
LER-79-008-03L, LER-79-8-3L, NUDOCS 7906080252
Download: ML19274F042 (1)

LER-1979-008, /03L-0 on 790420:breaker 1FA Failed to Trip When Control Switch Operated to Trip.Caused by Failure of Auxiliary Switch Contact Mounted Inside Breaker 1FA to Make Proper Electrical Contact.Breaker Inspected & Cleaned

Event date:
Report date:
2981979008R03 - NRC Website

text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION o'

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's LICENSEE EVENT REPORT CONTROL BLOCK: l l

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l l

lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6

p l E l C l P l R l 1 l@15l 0 l 0 l -l 0 l 0 l 0 0 l- 0l0l0l@l4 [1 ll Il l1 l@l l

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9 LICENSEE CODE 14 LICENSE NUM8ER 25 26 LICENSE TYPE J0 57 CAT 58 7

8 C ON'T S$RCs F l@l 0 5 10 l 0 10 l 2 l 9 l 8 @l 0 14 2l017l9l@l015111817 19 l@

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7 8

60 61 DOCKET NUVSER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PRO 8ABLE CONSEQUENCES h o

2 preaker 1FA failed to trip when its control switch was operated to trip. The breaker i

yas scheduled for a periodic inspection during niant shutdown. Breakers 1FA and 1AF, l

o 3

ponnected in series, tie the emergency bus IF to offsite power. On loss of offsite o

4 power,f reakers 1FA and 1AF trip and isolate the bus IF.

Similar problems occurred I

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pn January 12, 1977 (Report No. 76-60) and on February 17, 1978 (Recort No. 78-6).

No 1 0

7 l Significant occurrence took place. There was no effect upon public health and safety. l 0

8 l

SYSTEV

CAUSE

CAUSE COVP.

VALVE CODE CODE SUSCODE COVPONENT CODE SL8 CODE SUBCODE lElDl@ lB @ lC l@ l C l Kl T l B l R l K l@

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9 10 14 12 13 18 19 20 SEQUENTIAL OCCU R R E NCE REPORT REVISION LER RO EVENT YEAR REPORT No.

CODE TYPE N O.

@ REPORT l7 l9 l_

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,,,. 21 22 23 24 26 27 28 29 3J 31 J2 T KE ACTC ONP NT YET HOURS 22 SB IT FO A B.

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B 3J 34 35 36 31 40 el 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS l Auxiliary switch contact 52H/1N, mounted inside the breaker 1FA, apparently did not l

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lmake good electrical contact. The breaker was inspected, its auxiliarv switch cleaned I 3

gand good electrical contact verified. The breaker was trip tested after it was racked l in. In future breakers 1FA and 1GB will be trip tested after being racked in.

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% POWER OTHER STATUS 15 0 RY DISCOVERY DESCRIPTION lHlg l0l0l0lgl NA l

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• A$TiviTY CONTENT

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RELE ASED OF RELE ASE AVOUNT OF ACTIV,TY LOCATION OF RELEASE l Z l @ l Zlgl NA l

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9 9 10 11 44 45 80 PERSONNEL E XPOSURES NUY9ER TYPE

DESCRIPTION

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i IES PERSONNEL INJU DESCRiPriON@

NUVsEa 1010l01@l NA I

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8 9 11 12 80 LOSS OF CR DAVAGE TO F ACILITY TYPE D E SC RIP T'ON Lz J@l NA l

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8 9 10 68 69 30 5 Ladislav F. Bednar 402-825-3811 o

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