PNO-V-87-021, on 870310,reactor Tripped Due to Turbine Trip from Grounded Exciter.Caused by Maint Personnel Dropping Exciter Brush in Rigging.Licensee Plans Shutdown of Unit for 1 Wk to Perform Maint

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PNO-V-87-021:on 870310,reactor Tripped Due to Turbine Trip from Grounded Exciter.Caused by Maint Personnel Dropping Exciter Brush in Rigging.Licensee Plans Shutdown of Unit for 1 Wk to Perform Maint
ML20207T992
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 03/11/1987
From: Huey R, Johnson P
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-87-021, PNO-V-87-21, NUDOCS 8703240478
Download: ML20207T992 (1)


6-PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-87-21 Date: 3/11/87 ,

This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public int: rest significance. The information presented is as initially received without verification or evaluation and is basically all that is known by Region V staff on this date.

FACILITY: Southern California Edison Company Licensee Emergency Classification San Onofre Unit 1 Notification of Unusual Event DOCKET NO. 50-206 Alert Site Area Emergency General Emergency XX_,Not Applicable

SUBJECT:

SHUTDOWN GREATER THAN 48 HOURS At 1024 PST on March 10, 1987, with react'or power at 92%, the reactor tripped while personnel were performing preventive maintenance on the main turbine generator exciter brushes. An individual performing the maintenance dropped a brush into the rigging which grounded the exciter. This ground caused a loss of the generator field which resulted in a turbine trip. The end result was a reactor trip due to the turbine trip. The auxiliary feedwater system actuated in response to shrink in steam generator levels; other plant systems also functioned as required. There did not appear to be any significant damage to the exciter but the licensee indicated that current plans are to keep the Unit shutdown for approximately one week to perform maintenance items unrelated to the event. This event ended an 85 day continuous run.

The licensee is notifying local media.

This information is current as of 0900 PST, March 11, 1987.

CONTACT: P. Johnson R. Huey FTS 463-3745 (714)492-2641 Mf 9703240470 870311 DISTRIBUTION N-V -021 PDR H St. MNBB Phillips M E/W Willste Air Rights Mail:

Chairman Zech ED0 NRR IE NMSS ADM:DMB Comm. Roberts PA Com. Asselstine MPA AE0D Comm. Bernthal OGC Comm. Carr Regions:

SECY INP0 C g/ NSACf/ D ACRS Licensee! /_'% Axs7 CA (ReactorLicense~s) e REGION V: FORM 211 PDR Resident Inspector /ffry (Revised 3/14/83)

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