PNO-III-87-041, on 870319,turbine Tripped & Caused Reactor Scram.Caused by Fault in 6.9-kV & 4,160-volt Lines from Auxiliary Transformer to in-house Busses.Fault Also Caused Arcing & Burning of Busses.Fire Extinquished

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PNO-III-87-041:on 870319,turbine Tripped & Caused Reactor Scram.Caused by Fault in 6.9-kV & 4,160-volt Lines from Auxiliary Transformer to in-house Busses.Fault Also Caused Arcing & Burning of Busses.Fire Extinquished
ML20204F377
Person / Time
Site: LaSalle Constellation icon.png
Issue date: 03/20/1987
From: Ring M, Warnick R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-87-041, PNO-III-87-41, NUDOCS 8703260184
Download: ML20204F377 (1)
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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-III-87-41 ate March 20, 198 This. preliminary notification constitutes EARLY notice of events of POSSIBLE safety ,

or;public interest significance. The information is as initially receivea without.  !

v:rification or evaluation, and is basically all that is known by the Region III staff on this date.- ,

Facility: Commonwealth Edison Company Licensee Emergency Classification:

LaSalle Unit 1 Notification of an Unusual Event .

Marseilles, IL 61341 Alert Site Area Emergency & ,

Docket No. 50-373 General Emergency V l X Not Applicable Subj:ct: REACTOR TRIP; ARCING IN BUSS BARS FROM UNIT AUXILIARY TRANSFORMER j

-At 1:52 p.m. (CST), March-19, 1987, with the unit at 54 percent power, the generator shutdown, tripping the turbine and causing a reactor scram. All systems functioned as designed.

Tha generator shutdown was caused by a fault in the 6.9 kilovolt and 4160 volt lines from the unit auxiliary transformer to in-house busses located next to the Turbine Building.

(The cause of the fault is still under investigation.)

The transformer automatically tripped to isolate the affected busswork and the transformer deluge system activated. The fault also caused arcing and burning of the busses. The site fire brigade was sunsnoned and verified that the fire had been extinguished

-by 2:13 p.m. No offsite fire department was required. No injuries were reported. Initial damage repairs were expected to take about four days. A time estimate for complete repair has not been determined. (Unit 2 was not affected by this incident.)

Region III (Chicago) is following the licensee's course of action. <

The State of Illinois will be notified.

Regicn III was first informed of this event at 3:30 p.m. (CST), March 19, 1987. This information is current as of 11:50 a.m. (CST), March 20, 1987.

CONTACT:

WM. Ring EFW R. Warnick FTS 388-5602 FTS 388-5575 DISTRIBUTION:

H. St. ED0 NRR E/W Willste Mail: ADM:DMB Chairman Zech PA IE NMSS DOT:Trans only Comm. Roberts ELD OIA RES Comm. Asselstine AE0D NRC Ops Ctr 3'&6 Comm. Bernthal

-Comm. Carr SP 3.'32 Regional Offices ACRS SECY INP0 $30 NSAC 33/

CA RIII Resident Office PDR Licensee: 3'.39- (Corp. Office-ReactorLic.Only) p 0320 Region III PNO-III-87-041 PDR Rev. November 1986 g y ,

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