PNO-V-91-002, on 910303,Trojan Declared an Unsual Event & Initiated Plant Shutdown Due to Inability to Meet Requirements of TS 3.8.2.1,which Requires That Four 120 Volts AC Preferred Instrument Busses Be Operable

PNO-V-91-002:on 910303,Trojan Declared an Unsual Event & Initiated Plant Shutdown Due to Inability to Meet Requirements of TS 3.8.2.1,which Requires That Four 120 Volts AC Preferred Instrument Busses Be Operable

ML20203C210
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	03/05/1991
From:	Morrill P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-91-002, PNO-V-91-2, NUDOCS 9712150256
Download: ML20203C210 (1)

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p gyfg A l a m 0 g : p .I Vu lLj e PRFLIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-91-02 Date 03/05/91 6 preliminary notification constitutes EARLY notice of events of POSSIBLE safety or lic interest significance. The information presented is es initially received ,

hout verification or evaluation and is basically all that is known by Region V staff l f

cn this date, FACILITY: PORTLAND GENERAL ELECTRIC COMPANY Emergency Classification TROJAN NUCLEAR POWER PLANT X Notification of Unusual Event RAINIER, OREGON Alert DOCKET NO. 50-344 Site Area Emergency General Emergency Not Applicable

SUBJECT:

UNUSUAL EVENT AND PLANT SHUT 00WN At 5:50 P.M. PST on March 3,1991, Trojan declared an Unusual Event and initiated a plant shutdown due to the inability to meet the requirements of Technical Specification (TS) 3.8.2.1. TS 3.8.2.1 requires that four 120 volt AC preferred instrument busses be ep ;rable in Modes 1, 2, 3 and 4, and an inoperable bus is to be restored to operabla status t:ithin eight hours or the reactor must be in cold shutdown within the next thirty-six hours.

The preferred instrument bus was considered inoperable due to the unavailability of the preferred source which is the inverter powered by the associated battery. At 7:20 A.M. PST cn March 3,1991, the number four 120 volt AC instrument bus transferred from the preferred power source to the alternate power source as a result of an electrical fault in the inverter for the bus. When the licensee determined that repairs could not be expeditiously offected, the Unusual Event was declared and the plant shutdown was commenced.

A e Unit is currently in Mode S at 170'F. The licensee is testing the inverter after

/ ' lacino a resistor and a circuit board. The shutdown is expected to be longer than three (p)s.

Tho licensee notified the Resident Inspectors and the State of Oregon. A press release has b:en issued. Region V, v a the Resident Inspectors, will continue to monitor licensee d

cctions.

This information is current as of 11:30 A.M. PST on March 5, 1991.

CONTACT: P. Morrill, RV FTS 463-3740 L9 s!

FAX TO:,.

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