05000265/LER-1981-006-03, /03L-0:on 810312,differential Pressure Between Drywell & Suppression Chamber Was Lost.Caused by Isolation of Differential Pressure Sys Due to Short in Electrical Circuit Resulting in Blown Fuse.Fuse Replaced

/03L-0:on 810312,differential Pressure Between Drywell & Suppression Chamber Was Lost.Caused by Isolation of Differential Pressure Sys Due to Short in Electrical Circuit Resulting in Blown Fuse.Fuse Replaced

ML20008F722
Person / Time
Site:	Quad Cities
Issue date:	04/06/1981
From:	Wykoff D COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20008F721	List: 05000265/LER-1981-006, Forwards LER 81-006/03L-0 05000265/LER-1981-006-03, /03L-0:on 810312,differential Pressure Between Drywell & Suppression Chamber Was Lost.Caused by Isolation of Differential Pressure Sys Due to Short in Electrical Circuit Resulting in Blown Fuse.Fuse Replaced
References
LER-81-006-03L-01, LER-81-6-3L-1, NUDOCS 8104210540
Download: ML20008F722 (2)

LER-1981-006, /03L-0:on 810312,differential Pressure Between Drywell & Suppression Chamber Was Lost.Caused by Isolation of Differential Pressure Sys Due to Short in Electrical Circuit Resulting in Blown Fuse.Fuse Replaced

Event date:
Report date:
2651981006R03 - NRC Website

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LER NUMBER: LER/R0 81-6/03L-0 II.

LICENSEE NAME: Commonwealth Edison Company Quad-Cities Nuclear Power Station Ill.

FACILITY NAME: Unit Two IV.

DOCKET NUMBER: 050-265 V.

EVENT DESCRIPTION

On March 12, 1981, at 1:20 p.m., dif ferential pressure between the Dry-well and the Suppression Chamber was lost. The loss was caused by the isolation of the pressure suppression system due to an open fuse. The fuse blew when employees of a contractor inadvertently allowed the ends of two wires to come into contact while pulling them through flexible conduit in accordance with the approved station traveler procedure. This was beleg done to allow spare conductors from an existing cable to be routed through the conduit for attachment to spare contacts on the limit switches for valves A0-2-1601-21 and A0-2-1601-22. The spare contacts are to be used for a necessary computer input required for the Technical Support Center.

The open fuse was replaced and differential pressure between the Drywell and the Suppression Chanber was restored at 4:20 p.m.

The three hours without differential pressure was less than the six hour limit imposed by Technical Specification 3.7.A.6.a.(3).

VI.

PROBABLE CONSEQUENCES OF THE OCCURRENCE:

The occurrence had no effect on the safety of the plant. The Reactor Building Ventilation System isolated automatically and the Standby Gas Treatment System functioned as designed.

Vll. CAUSE:

The event was caused when personnel working on the Pressure Suppression System accidentally caused a short in one of its electrical circuits.

Vill. CORRECTIVE ACTICN:

The Imnediate corrective actions were to replace the open fuse and to re-establish the differential pressure between the Drywell and the Suppression Chamber. A meeting with personnel involved was utilized to Instruct them to take extra precautions in their work practices to avoid re-occurrence of this type of problem. No further corrective actions are considered necessary.