PNO-I-85-066, on 850907,fire Broke Out in Relay Room During CRD Surveillance Testing.Reactor Manually Tripped.Licensee Troubleshooting to Determine Cause

PNO-I-85-066:on 850907,fire Broke Out in Relay Room During CRD Surveillance Testing.Reactor Manually Tripped.Licensee Troubleshooting to Determine Cause

ML20137L883
Person / Time
Site:	Three Mile Island
Issue date:	09/09/1985
From:	Conte R, Kane W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-85-066, PNO-I-85-66, NUDOCS 8509130084
Download: ML20137L883 (1)

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DCS No: 50289850907 Date: September 9, 1985 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-I-85-66 1

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 Number 50-289 Site Area Emergency j General Emergency X Not Applicable i

1

Subject:

FIRE IN CONTROL R00 DRIVE POWER DISTRIBUTION PANELS 1 On Saturday, September 7, 1985, shortly before 4:00 p.m., the licensee conducted control rod drive surveillance testing. During the transfer of Regulating Bank No. 5

, (8 banks or groups of control rods exist) to the auxiliary power supply, lights on the j rod control panel brightened and blinked, indicating that an additional group i (No. 6) also was affected; and, shortly thereaf ter, a fire alarm annunciated in the control i room. The fire location was the relay room, which contains the control rod drive (CRD) power distribution panels along with integrated control system /nonnuclear instrumenta-

tion (ICS/NNI) panels. Sircultaneously, a security guard was in the area and the individual reported to the control room of arcing and smoke emitting from the CRD panels. Operators initiated a manual reactor trip to deenergize the system (3

58 p.m.). The trip opened two AC breakers which fed four DC breakers which also opened.

The fire brigade responded and only needed to expend one CO2 extinguisher. The j licensee needed no offsite fire assistance, and the fire was out within seven minutes.

4 Temperature in the room did not get high enough to activate the cardox system.

Extensive damage occurred to several transfer switches (relays) and wiring in the CR0 i

panels; however, the ICS/NNI panels were unaffected. It appears there was an equipment ,

malfunction that caused DC power supplies to parallel out of phase.

The licensee is in the process of repairs and troubleshooting to determine the cause of 1

the event, and to determine the extent of secondary ef fects, if any. Testing on repaired equipment is expected to occur tomorrow (Tuesday).

i CONTACT: R. Conte W. Kane FTS 590-1150 488-1126

DISTRIBUTION

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ACRS Air Rights INPO- -.

SECY SP NSAC p--

CA PDR Regional Offices TMI Resident Section 7 /')

RI Resident Office wa l' @91@e4850909 Licensee:

PNO-I-85-066 PDR (Reactor Licensees) i Region I Form 83 i (Rev. July, 1984) -

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