PNO-IV-89-026, on 890405,unit Tripped from 11% Power Due to Lockout of Main & Auxiliary Transformers During Attempt to Synchronize Main Generator to Electrical Distribution Sys. Unit in Hot Standby & Startup Not Expected Until 890409

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PNO-IV-89-026:on 890405,unit Tripped from 11% Power Due to Lockout of Main & Auxiliary Transformers During Attempt to Synchronize Main Generator to Electrical Distribution Sys. Unit in Hot Standby & Startup Not Expected Until 890409
ML20248J236
Person / Time
Site: South Texas STP Nuclear Operating Company icon.png
Issue date: 04/06/1989
From: Bruce Bartlett
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-89-026, PNO-IV-89-26, NUDOCS 8904140368
Download: ML20248J236 (1)


.

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. April':6, 1989 s,

1 V . PRELIMINARY: NOTIFICATION OF EVENT OR UNUSUAL 0CCURRENCE -- PN0-IV-89-26:

h This preliminary notification ~ constitutes EARLY notice of events of POSSIBLE -

R ;safetyi orLpublic' interest significance. The'information is as~ initially received r without verification or evaluation,-and is basically all that is known by.the Region IV staff ~on this date..

L FACILITY: Houston : Lighting & Power Company Licensee Emergency Classification:

South Texas Project . Unit 2 Notification of Unusual Event L Docket:: 50-499 , Alert Site Area Emergency General Emergency -

X Not Applicable

SUBJECT:

SHUTDOWN GREATER THAN 48 HOURS

- At approximately 7:25 a.m. -(CDT), South Texas Project (STP), Unit 2 tripped from

ll' percent reactor power because of a lockout of the main and auxiliary transformers;which occurred during an attee.pt to synchronize the main generator to' the electrical distribution system. . (See PNO-IV-89-24, April 5,1989.) _

f . Investigation by Houston.' Lighting 8 Power (HL&P) continues regarding what caused initiation of;the main and auxiliary transformer lockout when the main generator circuit breaker (GCB) was shut. HL&P has completed an-inspection of.the GCB and

.is currently testing the GCB discordance relay. HL&P anticipates performing functional. tests of the GCB and associated main-generator protective functions after identification of the cause of"the _ initiating event. STP, Unit 2, is in Mode 3'(Hot. Standby) and plant startup is not anticipated before-Sunday, iApril 9, 1989..

~HL&P has investigated and identified the causes of the problems with the nonsafety~ equipment noted in PNO-IV-89-24, April 5,1989.

Neither the licensee nor the NRC plans to issue a press release.

3 -Region IV received notification _of this occurrence by telephone from the Responsible Section' Chief onsite at 7:30 a.m. on April 6, 1989. Region IV hat

!1nformed EDO, NRR, and PA.

This-information has been confirmed with a licensee representative.

CONTACT: B. Bartlett, 728-8287 DISTRIBUTION: MAIL: DCS (Orig. IE34) 0WFN NMBB NL NMSS E0Ti ES DOT (Transp. Only)

Chmn. Zech SECY Comm. Roberts CA - NRR ARM Comm. Carr OGC OIA OGC FAX: (5520: Y /89 0 //.'09 Comm.~ Rogers GPA 01 TfiF0 gions & HQ)

Comm. Curtiss PA SLITP H-St- PDR ACRS- ED0 DE TH~ NSAC RRI NRC Ops Ctr Licensee (Reactor)

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8904140368 890406

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