ML20086C520

Interim Deficiency Rept Re Fire in safety-related Cable Tray Located in Auxiliary Bldg.Initially Reported on 740404. Caused by Slag from Welding Operation.Damaged Cables Will Be Replaced

ML20086C520
Person / Time
Site:	Salem
Issue date:	05/14/1974
From:	Betz J Public Service Enterprise Group
To:	Knuth D US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20086C518	List: ML20086C520
References
10CFR-050.55E, 10CFR-50.55E, NUDOCS 8311280101
Download: ML20086C520 (2)

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_ , V e-John F. setz Pubhc Service Electric and Gas Company 80 Park Place Newark, N.J. 07101 201/622-7000 Vice-President Electne Operation May 14, 1974 U. S. Atomic Energy Commission Directorate of Regulatory Operations 7920 Norfolk Avenue Bethesda, Maryland 20014 Attention of Mr. Donald F. Knuth, Director Gentlemen:

CABLE TRAY FIRE - AUXILIARY BUILDING NO. 1 UNIT SALEM NUCLEAR GENERATING STATION In compliance with AEC Regulation 10CFR50(e), a verbal report was submitted on April 4, 1974 to the Region 1 Directorate of Regulatorf 0.3 rations of a fire in a safety-related cable tray located in the Auxiliary Building of No. 1 Unit, Salem Kuclear Generating Station. Our review and analysis of this occurrence is as follows:

About 11:20 a.m. on Thursday, April 4, 1974 a fire occurred in Cable Tray No. 1C807. This tray is located beneath elevation 84 near the west end of the 4 kV switchgear room of the auxiliary building. At the time of the fire it contained 22 cables.

Just prior to the fire a welding operation on ventilating duct work was in process beneath this tray and horizontally displaced from the point of the fire by a distance of slightly less than two feet.

During the welding operation the top of the tray had been protected by a thermalon cover. After the welder had completed a portion of his weld he smelled smoke and lifted the thermalon cover to investigate the tray. At this point flames flared up in the midst of the Jables in the_ tray. TheLflames died out within a few seconds, after which some smoldering existed.- A fire extinguisher was used to assure that-the fire was com-pletely out. .Less than one. minute elapsed.from the time the 4 flaming occurred until the extinguisher was,used. i

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U.S. Atomic Energy 5-14-74 Commission A piece of slag, equivalent in composition to the 60-10 weld rod in use by the welder, was found at the point of the fire lodged between the cable and a rung of the tray. This could have been flung from the velding operation or the welder could have inadvertently struck an are at this point when moving his are gun toward or away from the point of welding.

An investigation of the cables in the tray revealed that seven cables showed evidence of some effects from the fire. All of the cables in the tray, including these seven, have been tested and found to have no shorts and all indicated positive megger values.

While all of the " damaged" cables are still electrically functional, as a precautionary measure they will be replaced with new cable.

This incident was construction-phase related and would not have occurred during normal operation of the plant. It is important to note that the cable construction performed in the expected manner in that the flame was self-extinguishing after the external source of heat was dissipated and that the cables remained functional.

Records of the repairs and work activities are available for your inspection at the Salem site. If you require additional information we will be pleased to discuss it with you.

Very truly y prs, -

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