ML19274F042

LER 79-008/03L-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

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: ML19274F040 ML19274F042
References
LER-79-008-03L, LER-79-8-3L, NUDOCS 7906080252
Download: ML19274F042 (1)

Text

NRC FORM 366 U. S. NUCLEAR REGULATORY COMMISSION

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" ' LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l lh (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6 o i p l E LICENSEE l C l PCODE l R l 1 14l@15l 0 l 0 l -l 0 lLICENSE 0 l-0 l 0 NUM8ER 0l0l0l@l4 [1LICENSE ll Il TYPEl1 l@l l 57 CAT 58 l@

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S$RCs60F l@l610 5 10 l 0 10 l 2 l 968l 8 69@l 0EVENT DOCKET NUVSER 14DATE 2l017l9l@l015111817 74 75 REPORT DATE 1980l@

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 o 3 yas scheduled for a periodic inspection during niant shutdown. Breakers 1FA and 1AF, l o 4 ponnected in series, tie the emergency bus IF to offsite power. On loss of offsite o 3 power,f reakers 1FA and 1AF trip and isolate the bus IF. Similar problems occurred I o 6 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 7

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/l [0l3 L 3J l-l l0l 26 27 28 29 31 J2 T KE ACTC ONP NT YET HOURS 22 SB IT FO A B. S PPLIE VANLFACTURER B

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44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS i o l Auxiliary switch contact 52H/1N, mounted inside the breaker 1FA, apparently did not l

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

, , gand good electrical contact verified. The breaker was trip tested after it was racked

, 3 l in. In future breakers 1FA and 1GB will be trip tested after being racked in. I 15 l 41 1 I 7 8 9 80 ST S  % POWER OTHER STATUS 15 0 RY DISCOVERY DESCRIPTION i s lHlg l0l0l0lgl NA l [Bl@l Observation A$TiviTY CONTENT *

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RELE ASED OF RELE ASE AVOUNT OF ACTIV,TY LOCATION OF RELEASE i s 9 9 l Z l @10l Zlgl NA l l NA ,

7 11 44 45 80 PERSONNEL E XPOSURES NUY9ER TYPE DESCRIPTION i

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80 LOSS OF CR DAVAGE TO F ACILITY TYPE D E SC RIP T'ON i 3 NA 8 9Lz_ J@l10 l

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I I IIIIIIIIIII I 7 8 9 10 68 69 30 5 NAVE OF PREPARER Ladislav F. Bednar 402-825-3811 o PHONE: $