PNO-V-85-033, on 850605,Channel C Reactor Trip Breaker Failed to Open During Surveillance Testing of Undervoltage Trip Attachment.Preliminary Info Indicates That Failed Breaker Refurbished During Current Outage

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PNO-V-85-033:on 850605,Channel C Reactor Trip Breaker Failed to Open During Surveillance Testing of Undervoltage Trip Attachment.Preliminary Info Indicates That Failed Breaker Refurbished During Current Outage
ML20125B789
Person / Time
Site: Rancho Seco
Issue date: 06/06/1985
From: Miller L
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-85-033, PNO-V-85-33, NUDOCS 8506110548
Download: ML20125B789 (1)


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h PRELIMINARY NOTIFICATION OF E?ENT OR UNUSUAL OCCURRENCE-PNO-V-85-33 Date: 06/06/85 Thia preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public int rest significance. The information presented is as initially received without verification cr cvaluation and is basically all that is known by Region V staff on this date.

FACILITY: Sacramento Municfpal Utility District Emergency Classification Rancho Seco Nuclear Power Plant Notification of Unusual Event Sacramento, CA Alert Docket No. 50-312 Site Area Emergency General Emergency XX Not Applicable

SUBJECT:

REACTOR TRIP BREAKER FAILS TO OPEN DURING SURVEILLANCE TESTING At 8219 PM (EDT) on June 5, 1985, the licensee notified HQ duty officer that the channel "C" r :ctor trip breaker (RTB) failed to open during surveillance testing of the undervoltage trip cttcchment . The RTB did open as required during testing of the shunt trip attachment. The plc t was in refueling shutdown (Mode 5) at the time. The licensee is replacing the failed RTB with another GE AK2-25 type DC breaker. The failed RTB is one of four DC breakers and 2 AC brn kers in the reactor trip system. Failure of a single RTB to open on a valid reactor pr;tiction signal would not have prevented insertion of the safety rods due to redundant br:ckers in the reactor trip system.

Praliminary information indicates that the failed RTB was refurbished during this refueling cutzge by Babcock & Wilcox, Lynchburg.

R:girn V Senior Resident Inspector and Project Section Chief will be attending a 2:00 PM (EDT) me: ting with licensee to get additional information on the failure mode. NRR (S. Miner, J.

Be:rd) will teleconference the meeting.

This information is current as of 11:00AM (PDT) June 6,1985.

CONTACT: L. Miller FTS 463-3869 DISTRIBUTION H St. f,,72__ MNB

.g Phillips 2% 2 :70 2 'K2 2:/7 E/W Willste Air Rights Mail:

Ch;irman Pallidino EDO NRR IE NMSS ADM:DMB Comm, Zech PA OIA RES DOT:Trans Comm. Bernthal MPA AEOD Only Comm Roberts Comm. Asselstine ELD Regions: b - 7 , W/ '

g,.y/ g -JlVg7 g yag-g SECY INPO#!o? NSAC ACRS Licensect ~7.*.7 V CA (Reactor Licensees) REGION V: FORM 211 PDR ResidentInspectorlJ'2- (Revised 3/14/83) 8506110548 050606 PDR I 8cE - -"

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