ML19329B656

RO NP-32-77-02:on 770527,while Replacing Cover on Crouse- Hinds Junction Box Containing Safety Features Actuation Sys Channel,Loose Output Lead Touched Box,Shorting to Ground. Caused by Insulation on Box Stripped Back Too Far

ML19329B656
Person / Time
Site:	Davis Besse
Issue date:	06/10/1977
From:	Bach S, Lingenfelter J TOLEDO EDISON CO.
To:
Shared Package
ML19329B568	List: ML19329B567 ML19329B656
References
NUDOCS 8002050765
Download: ML19329B656 (2)

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i e9 Lihile replacing the cover on a Crouse-Hinds Junction Box condaining SFAS j g l Channel, a loose output lead touched the box shorting to grodnd. HV-DHilsol r e9 as i es

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\ SUPPLEMENTAL INFORMATION FOR LER NP-32-77-2 DATE OF EVENT: May 27, 1977 . . ,

FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: A loose output lead in SEAS Channel 4 touched the cover on its Crouse-Hinds Junction Sox causing a short. A simulated RCS

- pressure rise and tripping of Decay Heat Pump #1-2 resulted in a violation of Technical Specification 3.4.1.

Conditions Prior to occurrence: The plant was in Mode 5. Power (MWT) 0 - Pcwer (MWE)0. RCS pressure less than 350 psig.

Description of Occurrence: Upon completion of ST 5031.02 in SFAS Channel 4, prior to replacing the cover on the Crouse-Hinds Junction Box, a loose output lead was discovered in the box. While tightening it, it momentarily touched the box. With the lead shorted to ground, current rose rapidly simulating an increase in RCS pressure. HV-DHil stroked closed at its setpoint of 433 psig.

The operator immediately tripped the Decay Heat Pump 1-2.

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N- / Designation of Apparent Cause of Occurrence: The insulation on the output lead had been stripped back further than necessary. (Improper installation)

Analvsis of Occurrence: The closing of DH 11 and subsequent de-energi:ation of Decay Heat Pump 2 caused Decay Heat flow to be less than 2800 gpm for 12 minutes. Since flow was not needed for decay heat removal and Decay Heat Pump 1-2 was re-started, no threat resulted to the health and safety of the public or to station personnel.

Corrective Action: The short was momentary. The bistable was then reset, HV-DHil reopened, Decay Hesc Pump was restarted and 3000 gpm flow restored to the RCS. A work request tas issued to insulate the bare wire to prevent re-

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currence. Also7 I&C Mecha'nics were ins' t ructed to be alert for similar situations and to initiate corrective action.

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Failure Data: No previous similar events have occurred.

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