ML19329B586

RO NP-33-77-04 on 770506,safety Feature Actuation Sys Channel 4 Put in Tripped Condition Due to Failure to Satisfy Acceptance Criteria for Surveillance Test.Caused by Circuit Board Failure.Circuit Board Replaced

ML19329B586
Person / Time
Site:	Davis Besse
Issue date:	06/06/1977
From:	Batch S, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19329B528	List: ML19329B525 ML19329B586
References
NUDOCS 8002050721
Download: ML19329B586 (2)

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L DATE OF EVENT: May 6, 1977 FACILITY: Davis-Besse Unit 1 ,

IPENTIFICATION OF OCCURRENCE: SFAS Channel 4, Containment Radiation was rendered inoperable due to failure to satisfy acceptance criteria for ST 5031.01. There-fore, the channel wss put in a tripped condition.

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Conditions Prior to Occurrence: Station in Mode 6. No core alterations in i progress.

1, j Description of Occurrence: At 0500, May 6, 1977, Surveillance Test ST 5031.01 on SFAS Channel 4 (Containment Radiation Channel) was being performed. The channel passed everything except check source response. Shift Foreman declared channel inoperable and put channel in tripped condition as per Action Statement No. 9 of . CTS Table 3.3.3.

- Designation of Aoparent cause of Occurrence: This event has been determined to

.be a failure in a circuit board in the Channel 4 Containment Radiation Module.

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Analysis of Occurrence: Since the other three SFAS Containoent Radiation Channels were still operable, the SFAS was still functional. No threat to i

the health and safety of the public or station personnel was realised.

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I Corrective Action: ISC investigated and found a defective circuit board which was replaced. The channel was then proven operable and returned to service.

l j Failure Data: No previous similar events have occurred.

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