PNO-V-87-016, on 870221,shutdown Commenced Due to Train B of Solid State Protection Sys Not Returning to Svc within 2 H. Caused by High Steam Generator Level on Generator 1-4 & Feedwater Flow Instabilities & Valve Position Problem

PNO-V-87-016:on 870221,shutdown Commenced Due to Train B of Solid State Protection Sys Not Returning to Svc within 2 H. Caused by High Steam Generator Level on Generator 1-4 & Feedwater Flow Instabilities & Valve Position Problem

ML20211Q440
Person / Time
Site:	Diablo Canyon
Issue date:	02/23/1987
From:	Mendonca M, Narbut P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-87-016, PNO-V-87-16, NUDOCS 8703030092
Download: ML20211Q440 (1)

, .- -

i 4 r PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-87-16 Date 02/23/87

.This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest 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: PACIFIC GAS & ELECTRIC COMPANY Emergency Classification DIABLO CANYON UNIT 1 X Notification of Unusual Event DOCKET N0.~50-275 Alert SAN LUIS OBISP0 COUNTY, CA _ Site Area Emergency General Emergency Not Applicable

SUBJECT:

UNIT 1 REACTOR SHUTDOWN REQUIRED BY TECHNICAL SPECIFICATIONS (TS)

AND SUBSEQUENT TURBINE TRIP / REACTOR TRIP At 5:05 am on February 21, 1987, while at 100% power, Unit 1 began an orderly shutdown in accordance with Technical Specification 3.3.1 and 3.3.2 since Train B of the Solid State Protection System (SSPS) had not been returned to service within the required two hours.

Earlier at 3:05 am, SSDS Train B had been removed from service for maintenance and testing activities. While testing the SSPS autcmatic function input " testing" lamp, an I&C technician created a small spark when placing the multimeter leads across the lamp socket.

The train B 48 vdc power supply breakers tripped, de-energizing the voltage coils on the Train B reactor trip breakers (RTB B and bypass breaker A). However, bypass breaker B had been closed when Train B was removed from service, and power remained supplied to the control rod mechanisms in accordance with Westinghouse design. I&C technicians re-energized the 48 vde power supply, and operators closed reactor trip breaker B. Both source range channels were identified to be energized, and remained offscale high for 22 minutes until the source range channels were placed in level trip bypass and their instrument power fuses were removed to de-energize the detectors. At 8:30 am SSPS Train B tas declared operable, and the plant power rampdown was discontinued. Evaluation and t: sting of the source range detectors was also successfully completed, and the detectors remained operable.

At 9:00 am, from 29% power, the unit experienced a turbine / trip reactor trip due to high stram generator level on steam generator 1-4. Feedwater flow instabilities and a feedwater flow regulating valve position problem contributed to the high level trip. The licensee is conducting further testing of the regulating valve and main feedwater control systems.

This information is current as of 9:00 am (PST) on February 23, 1987.

The media has shown interest.

CONTACT: M. Mendonca RV P. Narbut FTS 463-3720 805-595-7351

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! 0703030092 070223 /@s Mdh.J GA 7FI M V d -016 PDH

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