PNO-IV-89-024, on 890405,reactor Trip Occurred During Attempt to Synchronize Main Generator to Electrical Distribution Sys.Some Nonsafety Equipment Did Not Function as Expected. Resident Inspectors Will Continue to Monitor Activities

PNO-IV-89-024:on 890405,reactor Trip Occurred During Attempt to Synchronize Main Generator to Electrical Distribution Sys.Some Nonsafety Equipment Did Not Function as Expected. Resident Inspectors Will Continue to Monitor Activities

ML20244A709
Person / Time
Site:	South Texas
Issue date:	04/05/1989
From:	Bruce Bartlett NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-89-024, PNO-IV-89-24, NUDOCS 8904180156
Download: ML20244A709 (2)

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, ' . ll 4 April 5, 1989 l

l PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PN0-IV-89-24

[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 l Region IV staff on this date.

FACILITY: Houston Lighting & Power Co. Licensee Emergency Classification:

South Texas Project, Unit 2 Notification of Unusual Event (Docket: 50-499) Alert Site Area Emergency General Emergency X Not Applicable

SUBJECT:

REACTOR TRIP At approximately 7:25 a.m. (CDT),.STP, Unit 2, tripped from 11 percent reactor power, during an attempt to synchronize the STP, Unit 2, main generator to the electrical distribution' system. Immediately after shutting the main generator output breakers, STP, Unit 2, experienced a main turbine trip and loss of the STP, Unit 2, auxiliary transformer. The auxiliary transformer trip caused a loss of 13.8KV power and subsequent loss of reactor coolant pumps (RCP) and reactor trip (resulting from RCP undervoltage). The No. 21 standby diesel generator auto

. started and all safety systems appeared to function normally after the trip.

("A" 13.8KV bus had been supplied by the STP, Unit 2, auxiliary transformer; "B" and "C" 13.8KV busses were lined up to the Unit 2 standby transformer.) HL&P is investigating the cause of the main turbine generator and auxiliary transformer trips. This is the first reactor trip for STP, Unit 2, which was licensed for full power operation on March 28, 1989.

Some nonsafety equipment did not function as expected; for example, "D" RCP did not trip on bus undervoltage and the " Balance of Plant" (B0P) diesel generator did not auto start. ,

The Region IV section chief responsible for STP was in the control room at the time of the trip and observed the licensee's posttrip actions. The section chief and resident inspectors will continue to' monitor the licensee's troubleshooting activities.

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

Region IV received notification of this occurrence by telephone from the Section Chief at the site at 7:45 a.m. CDT. Region IV has informed EDO, NRR, and PA.

This information has been confirmed with a licensee representative.

CONTACT: B. A. Bartlett, 728-8287 l

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Comm. Rogers GPA 01 TNF0 Regions & HQ)

Comm. Curtiss PA SLITP H-St PDR ACRS ED0 OE FF NSAC RRI <

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DISTRIBUTION:

NRCRES, RESPN Research(PaulaDorm)

NRCRM, AE0D AE00 (Patty Wilson) ,

NRCRM, BROWN ARM (Karen Brown)

NRCRMP, 01ADW Inspector & Auditor (Displaywriter/PC)

.NRCRMP, 01DW Investigations (Displaywriter/PC) 1NRC02, OPAPN GPA:Public Affairs (Glady Ordaz) 1NRC0304, SLIPN GPA: State / Local Indian Tribes Program (Brenda Hill)

1NRC0304, NMSSPN Nuclear Material Safety & Safeguards (Pat Graaf) .

Nuclear Material Safety & Safeguards (Cathy Jenkins)

INRC0506, NMSSPN 1NRC0708, OEPN Enforcement (Betty Summers)

INRC1112, NRRPN Nuclear Reactor Regulation (Donna Berean)

INRC1516, 0GCPN General Counsel (Edna Downs)

INRC1718, ZECHPN Chairman (Lois Altoft)

INRC1718, ED0PN ExecutiveDirectorforOperations(DorisDay)

INRC1718, OCAPN GPA: Congressional Affairs (Janice Hester)

NRCRI, RIPN Region I NRCRII, RIIPN Region II NRCRIII, RIIIPN Region III NRCRIV, RIVPN Region IV NRCRV, RVPN Region V

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