ML19319B799

RO NP-33-77-58:on 770817,Control Rod 3,Group 5,indicator Found Misaligned to More than 6.5%.Caused by Loose Control Room Panel Indicator Connection.Connection Tightened & Indicator Returned to Correct Position

ML19319B799
Person / Time
Site:	Davis Besse
Issue date:	09/13/1977
From:	George T, Lingerfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19319B697	List: ML19319B696 ML19319B799
References
NUDOCS 8001270265
Download: ML19319B799 (2)

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@l Control Rod 3 of Group 5 indication was inoperable. The indicator light 7 89 g[ for Rod 3_showed that it was 100% withdrawn, but the indicator itself ]

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CAUST DE SCRIPTION gl Instrament and Control personnel found that connections on the Control  ;

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s s TOLEDO EDISc.. Ct.l'PANY DAVIS-BESSE UNIT ONE NUCLEAR POWEE STATION CI. SUPPLEMENTAL INFORMATIO?* F0.4 LER NP-33-77-58 DATE OF EVENT: August 17, 1977 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Control Rod 3 of Group 5 indicator was inoperable.

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

Description of Occurrence: At 1700 huurs on August 17, 1977, the Absolute Position Indicator (API) indicated that Control Rod 3 of Group 5 was sisaligned to greater than 6.5" of its group average. This placed the unit in Action Statement (a) of Technical Specification 3.1.3.3.

The indicator light for Rod 3 showed that it was 100% withdrawn; the indicator lights for the remaining control rods in Group 5 also showed 100" withdrawal.

Since relative and absolute positions on the computer indicated that all rods in Group 5 (including Rod 3) were 100% withdrawn, it was suspected that the API indi-g cator for Rod 3 was defective.

a Designation of Accarent Cause of Occurrence: Upon investigation, Instrument and Control personnel found the indicator to be freely movable. They checked the connections on the Control Room panel for Group 5, Control Rod 3 indicator and discovered the connection to be loose.

1 Analysis of Occurrence: There was no threat to the health and safety of the public or to station personnel. The control rod was actually aligned with the group, only the indication was incorrect. The control rod was operating properly.

j Corrective Action: At 2110 hours0.0244 days <br />0.586 hours <br />0.00349 weeks <br />8.02855e-4 months <br /> on August 17, 1977, the connection was tightened l

and the indicator returned to the correct position (100% withdrava) . This removed the unit from the Action Statement of Technical Specification 3.1.3.3. To further prevent recurrence, all connections on the Control Room panel Absolute Position Indicators were checked but no other connections were found to be loose.

Failure Data: On August 12, 1977 the API for Rod 4, Group 4, was inoperable dun to a bad relay.

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