ML19319B809

RO NP-33-77-64:on 770827,reactor Coolant Pump Motor 1-1-2 Tripped W/Instantaneous Ground & Differential Current Relay Indicating Fault.Caused by Damaged B&C Phase Surge Capacitors.Capacitors Repaired & Setpoints Reset

ML19319B809
Person / Time
Site:	Davis Besse
Issue date:	09/22/1977
From:	Beeler T, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19319B724	List: ML19319B723 ML19319B809
References
NUDOCS 8001270273
Download: ML19319B809 (2)

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O t TOLEDO EDISON CCMPANY DAVIS-3. ESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-64 i

DATE OF EVENT: August 27, 1977 j FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Reactor Coolant Pump Motor 1-1-2 was declared inoperable on August 27, 1977.

Conditions Prior to Occurrence: The plant was in Mode 2, with Power (%7) = 125 and Load (SI) = 0.

Description of Occurrence: Reactor Coolant Pu=p Motor 1-1-2 tripped at 17/.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> on August 27, 1977, with instantaneous ground (50GS) and differential current relay (87m/A-B-C) targets indicating the fault. This placed the Station into the Action Statement of Technical Specification 3.4.1 since one of the two Reactor Coolant Pumps in the loop were not in operation.

D Designation of Apparent Cause of Occurrence: Upon inspection of the Reactor Coolant Pump 1-1-2 =otor terminal box, Station maintenance personnel discovered B&C phase surge capacitors to be damaged. The exact cause of tha damage of the surge capacitors is not known.

Analysis of Occurrence: There was no danger to the health and safety of the 7

public or Station personnel. The ther=al pcwer was at a low value and the remaining three Reactor Coolant Pumps were supplying the required coolant flow.

i .;y Corrective Action: The high flux and the flux-delta-flux setpoints were reset for three pump operation as required by the Action Statement of Technical Specification 3.4.1. Station maintenance personnel replaced C-phase surge capacitors and re-installed B-phase surge capacitors after caulking the crack in the porcelain and opening in the seam with RTV silicone sealant.

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At 0058 hours6.712963e-4 days <br />0.0161 hours <br />9.589947e-5 weeks <br />2.2069e-5 months <br /> on August'317 1977, Reactor Coolant Pump 1-1-2 was declared operable.

This removed the station from Action Statement of Technical Specification 3.4.1.a.

On August 29, 1977, an inspection was made on the remaining reactor coolant pump motors. A defective capacitor was found in A phase for Reactor Coolant Pump 1-2-2.

Station maintenance personnel replaced A phase surge capacitor with a new one. A f Facility Change Request (77-280) has been prepared to investigate the position of the surge capacitors in the reactor coolant pu=p motor terminal boxes.

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i Failure Data: No previous similar events have occurred.

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