ML19326A558

RO NP-33-77-25:on 770726,safety Features Actuation Sys Channel 3 RCS Pressure Deliberately Placed in Test Trip Bypass to Replace Defective Relay.Relay Replaced & Channel Removal from Test Trip Bypass

ML19326A558
Person / Time
Site:	Davis Besse
Issue date:	08/19/1977
From:	Batch S, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19326A541	List: ML19326A540 ML19326A558
References
NUDOCS 8002040727
Download: ML19326A558 (2)

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(j\ TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE !P'iU POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-77-25 DATE OF EVENT: July 26, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Placed SFAS Channel 3 RCS Pressure in Test Trip Bypass (TTEP) to replace a defective relay.

Conditions Prior to Occurrence: The plant was in Mode 3, with Power (MWT) = 0 and Load (MWE) = 0.

Description of Occurrence: On July 26, 1977, at 0305 hours0.00353 days <br />0.0847 hours <br />5.042989e-4 weeks <br />1.160525e-4 months <br />, Safety Features Actuation System (SFAS) Channel 3 Reactor Coolant System (RCS) Pressure was placed in Test Trip Bypass (TTBP) to replace a defective relay. This placed the station into the Action Statement of Technical Specification 3.3.2.1. The relay (K4 on BA305 Bistable) controls indication for a " BLOCK" light in the Control Room only, and is not used to actuate equipment. The work was perfor ei s

g under Maintenance Work Order MWO 376-77. Work was completed and SFAS Channel ?

RCS Pressure was removed from Test Trip Bypass at 0325 hours0.00376 days <br />0.0903 hours <br />5.373677e-4 weeks <br />1.236625e-4 months <br /> on July 26, 1977.

Designation of Apparent Cause of Occurrence: The station deliherately entered the Action Statement of Technical Specification 3.3.2.1 to repisce the defec-tive relay. To prevent recurrence of the relay failure, the vendce, Consolidated Controls, is investigating a design change.

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Analysis of Occurrence: Since SFAS Channel 3 RCS Pressure was placed in Test '

Trip Bypass, and since the other three channels were operable, the SFAS would operate if required under accident conditions. Therefore, no threat occurred to the health and safety of the public or to station personnel.

Corrective Action: The relay was replaced within twenty (20) minutes and the channel removed from Test Trip Bypass. Facility Change Request FCR 77-104, written on June 23, 1977, requested a design change to prevent relay failure.

Consolidated Controls is currently investigating a design change to identical relays in the SFAS to prevent recurrence.

Failure Data: No previous similar events have occurred.

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