PNO-III-89-016, on 890303,Unit 1 Reactor Scrammed from 86% Power as Result of Turbine Trip,Which Appeared to Be Related to Fault in Unit 2 Sys Auxiliary Transformer. Unit 1 Expected to Remain Shut Down for Three Days

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PNO-III-89-016:on 890303,Unit 1 Reactor Scrammed from 86% Power as Result of Turbine Trip,Which Appeared to Be Related to Fault in Unit 2 Sys Auxiliary Transformer. Unit 1 Expected to Remain Shut Down for Three Days
ML20198K769
Person / Time
Site: LaSalle  Constellation icon.png
Issue date: 03/03/1989
From: Forney W, Harrison J
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:
References
PNO-III-89-016, PNO-III-89-16, NUDOCS 9710240123
Download: ML20198K769 (2)
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PRELIMINARY NOTir1 CATION Or EVENf OR UNUSUAL OCCURRENCE PNO-III-89-16 Date March 3,1989 This preliminary notification constitutes EARLY notice of events of POSSIBLE afety or pubite interest significance. The information is as initially Seceived without verification or evaluation, and is basically all that is M known by the Region 111 staff on this date.

Facility: Commonwealth Edison Co. Licensee Emergency N '

N LaSalle Units 1 & 2 classification:

Marsellies, IL 61341 X Unusual Event Alert

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Docket Nos. 50-373; Site Area Emergency 50-374 General Emergency Not Applicable

Subject:

UNIT 1 REACTOR SCRAM RELATED TO UNIT 2 TRANSFORMER FAULT At 11:02 p.m., the Unit I reactor scrammed from 86 percent power as a result of a turbine trip, which appears to have been related to a fault (short) in the Unit 2 System Auxiliary Trans fomer. Prompt action by the Unit 2 reactor operator prevented a scram of that unit, which remains in operation.

Unexpected equipment responses occurred on both units -- the station air system compressors for both units were lost; the process computer failed; the reactor building ventilation systems isolated for both units; the Unit 2 alternate reactor protection system breakers trip >ed (although the unit was on normal power sources); and a Unit 2 flow control valve in tie recirculation system locked up. All these equipment problems were corrected by 12:00 midnight.

When the Unit 2 transformer failed, the electrical loads were automatically transferred to he Unit Auxiliary Transformer, the unit's second source of off-site power. The two mergency diesel generators associated with these electrical loads were not required and did ot start. A third diesel generator, which powers the high pressure core spray system, did start system.

and remained in operation to ensure the availability of the high pressure core spray The licensee also reported that some Unit I water level alarms were received early, indicating possible setpoint drifting in the associated Static-0-Ring switches.

The licensee declared an unusual Event under its emergency plan.

The cause under of the Unit 2 transformer failure and its connection with the Unit 1 scram are investigation. The licensee expects Unit 1 to remain shut down for three days for unrelated maintenance. With the transformer out. Units I and gare in a 72-hour Limiting Condition for Operation (LCO) requiring shutdown if the second source of off-site power is not restored.

restored to serviceThelicenseebelievestheUnit2systemauxilgary[transformerwillbe before the 72-hour clock expires.

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DISTRIBUTION:

WHITE FLINT NORTH 1 MNBB 6 m REGIONS FAX T0: u U!

Chairman Zech CA XMD RI INPO Com Roberts OGC ARM RI! NSAC Comm. Carr 01 O!A Rly Licensee om. Rogers EDO RV NRC Ops Ctr imm. Curtiss NRR NL MAIL TO: PDR (8/634-3T437 ECY NMSS R$ DCS(Orig.)

GPA/SLITP/PA ACRS DOT (Trans. Only) 23 890303 h02 Rev. 03/01/89 PNO-1II-89-016 PDR

PMLtMINARY N0TlflCAT10g 0F EVENT OR UNUSUAL OCCURRENCE--PNO-!!!-89-16 Date March 3,1989 )

-2 IO LAe NRC Senior Resident Inspector has been on-site since about 2 a.m., March 3,1989. An Augrnented Inspection Team (AIT) has been dispatched to the site, headed by the Dresden Senior ,

Resident Inspector. Additional team members include tho LaSalle resident inspectors, two Region !!! (Chicago) electrical specialists, and an NRR representative.

The State of Illinois will be notified.

The Itcensee notified the Headquarters Operation Center of this event at 1:04 a.m. (CST).

March 3, 1989. This information is current as of 10:30 a.m., March 3, 1989.

h CONTACT: Y. Harrison

. o ney FTS 388-563b FTS 388-5590 O

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