ML19316A582

AO-270/75-13:on 750728,string of Keowee & Switching Station Batteries Simultaneously Removed from Svc.Caused by Operator Error.Charging Procedure for Battery Sys Revised to Require Control Operation Confirmation Prior to Charging

ML19316A582
Person / Time
Site:	Oconee
Issue date:	08/11/1975
From:	DUKE POWER CO.
To:
Shared Package
ML19316A581	List: ML19316A580 ML19316A582
References
NUDOCS 8001130087
Download: ML19316A582 (2)

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DUKE POWER COMPANY OCONEE UNIT 2 Report No.: A0-270/75-13 Report Date: August 11, 1975 Occurrence Date: July 28, 1975 Facility: Oconee Unit 2, Seneca, South Carolina Simultaneous outage of one string of Keowee Identification of Occurrence:_ batteries and one string of switching station batteries Conditions Prior to Occurrence: Unit at rated power Description of Occurrence:

On July 28, 1975, during the process of planning the startup of Unit 1 (Units 2 and 3 in full power operation), it was discovered that one string of Keowee batteries and one string of switching station batteries were being charged and were therefore out of service simultaneously. The charging of the Keovec batteries (one string) had begun at 0850 hours0.00984 days <br />0.236 hours <br />0.00141 weeks <br />3.23425e-4 months <br />, July 28, 1975, and the charging of the switching station batteries (one string) had begun at 0915 hours0.0106 days <br />0.254 hours <br />0.00151 weeks <br />3.481575e-4 months <br />, July 28, 1975. Although the control operator was notified that these batteries were to be taken out of service, he failed to recognize that they should not be taken out of service simultaneously.

When the error was discovered at 1535 hours0.0178 days <br />0.426 hours <br />0.00254 weeks <br />5.840675e-4 months <br />, power reduction of Units 2 and 3 was immediately initiated to bring the units to a hot shutdown. The batteries were returned to service at 1554 hours0.018 days <br />0.432 hours <br />0.00257 weeks <br />5.91297e-4 months <br /> and power reduction ceased.

Designation of Apparent Cause of Occurrence:

The apparent cause of this occurrence was operator error in that he failed to realize that the two sets of batteries should not be tahan out of service simultaneously.

Analysis of Occurrence:

The one string of switching station batteries and the one string of Keowee batteries were out of service for approximately six hours and forty minutes, during which time the station operated normally. The switching station battery system is a redundant system which provides emergency power for primary control and protective relaying when normal AC rectified power is unavailabic. Similarly, the Keowce batteries, one string for each Keowce unit, provide emergency Keowee station power when the normal power is unavailabic. One string of each of the two systems has the capacity for handling full loads during an emergency situa; ion. Therefore, it can be concluded that the health and safety of the public were not affected by this j occurrence.

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_2-Corrective Action:

The charging procedure for the Keowce battery system and the switching station battery system will be revised to require confirmation from the control operator that when it is desired to charge one of these systems (either Keowce or switching station), the other system is not being charged at the same time. Additionally, all operating personnel have been instructed to review the incident report and pertinent sections of the Technical Specifi-cations.

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