ML19326A556

RO NP-33-77-27:on 770719,J Bus Deliberately de-energized to Install Secondary Terminal Box.Caused by Load Dispatcher Request.On 770719,air Circuit Breakers Closed to re-energized J Bus

ML19326A556
Person / Time
Site:	Davis Besse
Issue date:	08/12/1977
From:	Beeler T, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19326A537	List: ML19326A536 ML19326A556
References
NUDOCS 8002040723
Download: ML19326A556 (2)

Text

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 \_/               .            DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-27 DATE OF EVENT: July 19, 1977 FACILITY: Dav'is-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: De-energizing "J" Bus which removed one of the two required independent offsite 345 KV transmission lines.

Conditions Prior to Occurrence: The plant was fn Mode 4, with Power (MWT) = 0 and Load (MWE) = 0. Description of Occurrence: At 0530 hours on July 19, 1977', the load dispatcher requested that "J" Bus be de-energized. This placed the station into the Action Statement of Technical Specification 3.8.1.1 since one of the two required inde-pendent offsite 345 KV transmission lines was removed from service. A verification of breaker alignment was made for the remaining offsite 345 KV transmission line and onsite Class lE Electrical Distribution System. Both in-fN1 dependent diesel generators were started and accelerated to E 900 rpm in d 10 ( seconds. This was completed by 0555 hours on July 19, 1977, in accordance with

   \        the Action Statement.

Designation of Apparent Cause of Occurrence: "J" Bus was de-energized by the Shift Foreman at the request of the Load Dispatcher so that Power Systems per-sonnel could install a secondary terminal box on "J" Bus Coupling Capacitor Po-tential Devices (CCPD) for testing purposes. Analysis of Occurrence: Since there was one 345 KV transmission line, one 345 - 13.8 KV startup transformer and one 13.8 KV Bus operable with two independent diesel generators to provide AC power, there was no threat to the health and safety of the public or station personnel. Corrective Action: At 1904 hours on July 19, 1977, air circuit breakers 34560 and 34563 at the Davis-Besse Station 345 KV Switchyard were closed to re-energize "J" Bus. This removed the station from Action Statement of Technical Specification 3.8.1.1. Failure D:ta: No previous similar events have occurred.

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