ML19345C809

LER 80-082/03L-1:on 801030,review of 801010 Event Re Overcurrent Trip of 480-volt Breaker B52-204 Revealed Similar Events Occurred in June 1979 & Apr 1980.Cause Unknown.Review of Current Loading Requested

ML19345C809
Person / Time
Site:	Pilgrim
Issue date:	12/01/1980
From:	Mcloughlin M BOSTON EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19345C807	List: ML19345C806 ML19345C809
References
LER-80-082-03L, LER-80-82-3L, NUDOCS 8012080417
Download: ML19345C809 (1)

Text

NRC FCRM .',66 (7-77)

LICENSEE EVENT REPORT a

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(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) lo lt 8I 9l Ml Al Pl Pl Sl 1l@l 0 l 0 l -l 0 l 0 l 0 l 0 ] 0 l - l 0 l 0 l@l 4 l 1 l 1 l 1 l 1 l

l@l Si CAT 68 lg 14 15 LICENSE NUMSER 25 26 LICENSE TYPE JG 7 LICENSEE CODE CON'T l0l1l 7 8 S$Rc}lL 60

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-l 0 l 2 l 9 l 3 @l 110 ! 3 l 0 l 8 l 0REPORT 68 69 ev ENT DATg 74 75 l@lDATE 1l 2 l 800 l 1[ 8 l 0 EVENT OESCRIPTION AND PROBABLE CONSEQUENCES h l o l 21 l ORC review on October 30, 1980 of an October 10, 1980 event concerning an overcurrent i Io Ial l trip of 480 volt breaker B52-204 revealed that similar events had occurred which il l o 14 l l should be reported. In June 1979 and again in April 1980 480V bus BIS had tripped andl 101 s 1 l operator action was required to restore it to service. The overcurrent trip and manual1 l 016 l l reClosure of 480 volt breaker B52-103 temporarily resulted in the unavailability of sj l O I 7 I l single loop of the RBCCW System and other safety related equipment. l l

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12 13 18 79 20 7 8 9 10 11 REVISION SEQUENTI AL OCCURRENCE REPORT CODE TYPE N O, EVENT YE AR REPORT NO.

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._ l218l0l 22 23 24 26 27 28 29 30 31 32 NOURS S8 iT POR 1 8. SUPPLIE MAN FACTURER K N AC 0 ONP NT M lEl@lFl@ W@ [,,Z_j@ l 0 l0 l0 l0 l l41N l@ l42N l@ lNl@ l44G l 0 l 8 l 047 l@

JJ 34 35 36 3/ 40 43 CAUSE DuCRIPTION AND CORRECTIVE ACTIONS lilo1iFollowing the June 1979 trip, the breaker relays were tested and found to be operating; ji jij lwithin their time current curves. The breaker was overhauled and no problems were l

,,,,,l detected. Following the April 1980 trip, the breakers overcurrent trip settings were l

,, i3, l increased but maintained within their intended operating ranste. A detailed review of l l

g l the current loading of 480V buses B14 and B15 has been requested from Engineering. 80 7 8 9 oTHER STATUS 15 A DISCOVERY DESCRIPTION S  % POWER l Operational Event l N.A. lAl@l W'

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8 ACTIVITY CO'0 TENT 4 mount OP ACTIVITY LOCATION OP RELEASE REttASEO OP RELEASE N.A. N.A.

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j PERSONNEL EXPOSURES NUV8ER TYPE CESCRIPTION l i l 7 l l 0 l 0 l 0 l@[_,2,,j@l N.A. l PERSONNE L INJURIES NOV8 E R DESCRIPTION l

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80 LOSS OF OR OAMAGE TO PACILITY TYPE OESCR:PTioN 7

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7. 8 9 hl 10 N.A. l 68 69 lllllllllllll3 30 3 M. Thomas McLoughlin PH@N E: b