ML20027A240

LER 78-067/03L-1:re Failure Data for Decay Heat Flow.Caused by Personnel Error in Deenergizing Essential Bus

ML20027A240
Person / Time
Site:	Davis Besse
Issue date:	09/27/1978
From:	TOLEDO EDISON CO.
To:
Shared Package
ML20027A235	List: ML20027A233 ML20027A236 ML20027A237 ML20027A240 ML20027A241
References
LER-78-067-03L, LER-78-67-3L, NUDOCS 7810310342
Download: ML20027A240 (1)

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t TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWR STATION SUPPLEMENTAL INFORMATION FOR LER NF-33-78-81 PAGE 2 OF 2 Designation of Apparent Cause of Occurrence: All three incidents were caused by personnel errors. The electrician bumped into the undervoltage relay.

The operator lined the synchroscope to the wrong bus for both attempts to trans-fer essential bus D1 power supply from Diesel Generator 1-2 to bus D2.

Analysis of Occurrance: There was no danger to the health and safety of the public or to unit personnel. The core decay heat was extremely low since the unit had been shutdown since April 28, 1978. The brief loss of decay heat flow did not cause excessive co e temperatures.

Corrective ' Action: .At 1621 hours0.0188 days <br />0.45 hours <br />0.00268 weeks <br />6.167905e-4 months <br /> on June 15, 1978, essential bus D1 was re-energized i by performing a'" dead transfer" from the Control Room of power from bus D2 to essen-tial bus D1.

The operator was instructed to be more careful when transferring bus power and the electricians were instructed to be more careful when working on live breakers.

Failure Data: A previous loss of decay heat flow due to an essential bus being y de-energized by personnel error was reported in Licensee Event Report NP-33-78-72.

The bus was de-energized initially at different locations and personnel were

- performing different activities at the time of the incidents.

LER #78-067 7810310342-

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