PNO-V-87-084, on 871216,licensee Induced Unexpected Load Transient on One safety-related Diesel Generator During Loss of Offsite Power Test.Dhr & Control Units Unaffected.Cause Being Investigated

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PNO-V-87-084:on 871216,licensee Induced Unexpected Load Transient on One safety-related Diesel Generator During Loss of Offsite Power Test.Dhr & Control Units Unaffected.Cause Being Investigated
ML20237C623
Person / Time
Site: Rancho Seco
Issue date: 12/16/1987
From: Dangelo A, Miller L
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-87-084, PNO-V-87-84, TAC-63030, NUDOCS 8712220038
Download: ML20237C623 (1)


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k r PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PN0-V 87-84 Date 12/16/87 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The ir. formation presented is as initially received ,

without verification or evaluation and is basically all that is known by Region V staff on this date.

FACILITYi SACRAMENTO MUNICIPAL UTILITY DISTRICT Cmergency Classification RANCHO SECO UNIT 1 Notification of Unusual Event DOCKET N0. 50-312 Alert HERALD, CA Site Area Emergency General Emergency

_X_Not Applicable

SUBJECT:

STOP WORK ORDER ISSUED ON RANCHO SECO TESTING DUE TO IMPROPER PARALLELING 0F EMERGENCY DIESEL GENERATOR At approximately 7:30 am (PDT) on Wednesday, December 16, 1987, during the conduct of a loss of offsite power test, the licensee induced an unexpected load transient on one of the four safety related diesel generators. This occurred when the licensee attempted to shift loads to offsite power to allow securing the diesel when a governor control oil leak occurred.

When the diesel was paralleled to offsite power the diesel load rose to a maximum of approximately 3,300 kilowatts. The original load prior to paralleling was approximately 200 kilowatts. Operator action to reduce load caused diesel load to go to zero and caused a reverse power condition on the generator. Licensee personnel were unable to remotely open the diesel generator output circuit breaker since only one of two SFAS signals had been reset. Licensee personnel subsequently manually tripped the diesel generator locally, ending the event.

The transient did not interrupt decay heat removal or interfere with any control circuits.

All 4KV electrical buses are currently aligned to their normal offsite power sources.

The licensee has issued a Stop Work Order which has stopped all System Review and Test Program testing until the root cause of the transient has been determined, and appropriate corrective actions have been completed.

There has been local media interest.

This information is current as of 4:00 pm (PST) December 16, 1987.

CONTACT: L. Miller A. D'Angelo FTS 463-3869 (209) 748-2791 l DISTRIBUTION BY 5520: FAX T0:

l Date Time Date n Time f Chairman Zech EDO RI INP0 l Comm. Roberts AEOD RII NSAC l Comm. Bernthal PA0 RIII LICENSEE Comm. Carr SLITP RIV RESIDENT INSPECTOR ~

Comm. Rogers NRR HQS. OPERATIONS OFFICER '

SECY NMSS f CA ARM MAIL T0:

PDR 01 DCS (Original)

OGC OIA DOT:(Trans. Only. Applicable State)

ACRS RES GPA 8712220038 871216 RV FORM E11 ]$ ' 3

$-V -084 DCD Revised: 8/19/87 o