ML19319B801

RO NP-33-77-60:on 770816,electrolte Level Found Too Low for Station Battery Cell 2N-41.Caused by Personnel Covering Vent Cap Opening.Maint Work Order 77-1698 Initiated to Bypass Cell 2N-4L.Cell 2N-41 Checked for Cracked & Leaks

ML19319B801
Person / Time
Site:	Davis Besse
Issue date:	08/13/1977
From:	Baltz J, Grime L, Lingerfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19319B699	List: ML19319B698 ML19319B801
References
NUDOCS 8001270267
Download: ML19319B801 (2)

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DAVIS-BESSE UNIT CNE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-60

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DATE OF EVENT: August 16, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Electrolyte level too low for Station Battery Cell 2N-41.

Conditions Prior to Occurrence: The plant was in Mode 2, with Power (MWT) = 0, and Load (MWE) = 0.

Description of Occurrence: At 0845 hours0.00978 days <br />0.235 hours <br />0.0014 weeks <br />3.215225e-4 months <br /> on August 16, 1977, the battery cell 2N-41 electrolyte level was found to have been below the minimum allowable level. This occurrence was discovered by Maintenance personnel while monitoring the batteries during equalization.

This placed the station in the Action Statement of Technical Specification 3.8.2.3 which requires that 250/125 volt DC MCC 2, 125-volt DC Station Batteries and Chargers s must be energized and operable.

Designation of Anoarent Cause of Occurrence: The low electrolyte level was believed to have been caused by personnelerror in setting a flexible plastic container of electrolyte on the vent caps, thus covering the vent opening in the cap. This prevented the gas from escaping the cell, causing a pressure increase within the cell, thus forcing the electrolyte out the withdrawal tube. The bottle contained the electrolyt .

that had been removed to avoid violation of the high electrolyte limit set by Techni-cal Specification 4.8.2.3.2-b-3.

Analysis of Occurrence: The occurrence initiated no danger to the health and safety of the public or to station personnel. The batteries were capable of delivering all the capacity required for the emergency load even with the low electrolyte level in Call 2N-41 or with up to 2 cells out of service.

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Corrective Action: All containers were removed from the tops of the cells. Main-tenance Work order 77-1698 was initiated to jumper around Cell 2N-41. Bypassing the cell restored Battery 2N to operability at 1130 hours0.0131 days <br />0.314 hours <br />0.00187 weeks <br />4.29965e-4 months <br /> on August 16, 1977. Cell i 2N-41 was removed to allow the battery vendor to investigate for cracks and leaks but none were found. After a complete investigation, the cell will be replaced in the battery string. Maintenance Instructions will be revised to prohibit the place-ment of articles on cells that may block battery vents. This should prevent recurrence of this low electrolyte level due to vents being obstructed.

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( Failure Data: The station batteries have not previously been inoperable due to low electrolyte levels.

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