PNO-I-85-067, on 850923,malfunction of One Reactor Protection Sys Ac Breaker Caused Small Electrical Fire.Operator Deenergized Breaker from Feeder Bus & Fire Extinguished. Spare Breaker Installed

PNO-I-85-067:on 850923,malfunction of One Reactor Protection Sys Ac Breaker Caused Small Electrical Fire.Operator Deenergized Breaker from Feeder Bus & Fire Extinguished. Spare Breaker Installed

ML20132E335
Person / Time
Site:	Three Mile Island
Issue date:	09/24/1985
From:	Conte R, Kane W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-85-067, PNO-I-85-67, NUDOCS 8510010062
Download: ML20132E335 (1)

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DCS No: 50289850924 Date: September 24, 1985.

PREllMINARY NOTIFICATION OF EVENT 0R UNUSUAL OCCURRENCE--PNO-I-85-67 i

' This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region I staff on this date.

Facility: .

Licensee Emergency Classification:

GPU Nuclear Corporation Notification of Unusual Event Three Mile Island, Unit 1 Alert Docket No. 50-289 Site Area Emergency General Emergency X Not Applicable

Subject:

REACTOR PROTECTION SYSTEM BREAKER MALFUNCTION On September 23,1935 at 1:27 p.m. a malfunction of one of two reactor protection 4

system AC breakers occurred resulting in a small electrical fire. Within a minute the operator de energized the breaker from a feeder bus and the fire was extinguished using a manual extinguisher. No fire brigade or offsite assistance was required. A reactor trip signal was not generated because the other AC breaker remained closed The plant was in a hot shutdown condition with safety rods withdrawn at the time of the event.

The event occurred during weekly RPS surveillance testing in preparation for the pending restart. The under-voltage test was completed satisfactorily, however, when the breaker was reset for the shunt trip test, it only partially closed. Locally, technicians attempted to use the shunt trip to open the breaker, but the breaker did not move. The switch that the technician actuated apparently put a seal-in function 4

to the shunt trip coil that is de energized only when the breaker is fully open and the prolonged current through the shunt coil caused it to overheat. Based on visual inspection apparently only the shunt coil was damaged. Additional inspection and l testing is being conducted. A spare breaker has been installed and is under going surveillance testing. The TMI-1 restart staff is following the licensee's corrective actions.

, CONTACT: R. Conte W. Kane FTS 590-1156 590-1167 01STRIBUTION:

H. St. MNBB Phillips E/W Willste Mail: ADM:DM8 Chairman Palladino ED0 NRR IE NMSS DOT:Trans only Comm. Zech PA OIA RES Comm. Bernthal ELD AE00 Comm. Roberts

, Comm. Asselstine i ACRS Air Rights INP0 g---

SECY SP NSAC D lCA PDR Regional Offices .

TMI Resident Section 1 1 _

RI Resident Office A t_

Licensee:

(ReactorLicensees}

Region I Form 83 (Rev. July, 1984) e510010062 050924 PDR ILE PNO-1-05-067 PDR 0\

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