ML17266A371

LER 80-061/03L-0:on 801027,dc Electric Buses Were Switched Into Configuration Such That One Dc Bus Provided Control Power for Both Component Cooling Water Loops.Caused by Electrical Maint Activity

ML17266A371
Person / Time
Site:	Saint Lucie
Issue date:	11/26/1980
From:	Pace P FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML17209A407	List: ML17209A406 ML17266A371
References
LER-80-061-03L, LER-80-61-3L, NUDOCS 8012050470
Download: ML17266A371 (3)

Text

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'hile activities re uired switchin of DC, Elect Buses into a configuration such that one DC Bus provided control power for both CCH loops. Action was taken er tech s ec 3.7 '. 1 and two independent CCH loops were reestablished in 45 minutes. This was well within the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limit. This event was the second occurrence of not havin two inde endent CCW loo s See LER 77-31 . No safet limits

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<<OURS Q22 4O SUSMITTCO LQQ 4 I LKQ 4'3 I'IQ 43 44 41 CAUSE DESCRIPTION ANO CORRECTIVE ACTIONS Q29 It was necessary during e>ectrical maintenance activities to provide control power for both CCW Loops from the same bus. This resulted in loss of inde endence of the CCH Loo s. After maintenance activities were completed, the two independent CCH Loops were again established. The attachment contains a detailed se uence of .events.

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k Reportable Occurrence 335-80-61 Licensee Event Report Pag'e Two P

CAUSE DESCRIPTION AND CORRECTIVE ACTION The plant was operating at 100% power with the "C" CCW Pump aligned to the "A" header and supplied from the "A" Electrical Buses (via the "AB" Buses). The "B" CCW Pump was aligned to the "B" header and supplied from the "B" Electrical Buses.

A ground was detected on the "B"b'attery charger and it was taken out of. service for maintenance. To maintain the "B" DC Bus, the "AB" Bus was separated fro'm the "A" Bus, thc "AB" charger placed on the "AB" Bus and the "B" Bus fed from the ",AB" Bus.

This configuration r'esulted in both the "B" and the "C" CCW Pump DC control power being fed frotn the "AB" charger and two "independent" CCW loops were not available.

The "B" battery charger was repaired and the DC Buses were realigned to provide two independent CCW loops within 45 minutes.