ML19242D199

Significant Deficiency 79-1:during Installation of Equipment on Section of Main Control Board,Deficient Skip Weld of Wire Duct Detected.Investigation Revealed 60 Improper Welds.All Welds Will Be Repaired by 790629

ML19242D199
Person / Time
Site:	Catawba
Issue date:	06/21/1979
From:	DUKE POWER CO.
To:
Shared Package
ML19242D190	List: ML19242D189 ML19242D199
References
NUDOCS 7908140679
Download: ML19242D199 (2)

Text

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DUKE POWER COMPANY CATAWBA UNITS 1 AND 2 Report No.- 50/413-414/79-1 Report Date: July LO, 1979 Facility: Catawba Nuclear Station-Units 1 & 2 Identification of Deficiency: Main Control Boards Defective Welds Description of Defi.iency: _

During the installation of wiring and equipment on the IMN1 section of the main control board for Unit 1, an apparent deficient skip weld of a wire duct to the board structure was detected. During further inspection, other welds were observed on main control boards for both units which appeared deficient. The manufacturer was called in to reinspect these control boards and investigate the cause of any deficient welds. The inspection identified 60 welds broken or of que -

tionable quality. These were found in various random locations and included welds between structural members and welds betwcan stiffeners and the panel surface metal.

This deficiency was reported to NRC Region 11 on June 21, 1979 as a reportable item under IOCFR50.55(e).

The panels were manufactured by Frank Electric Co. at their York, Pa. plant, over a period of time from July 1,1977 to September 1, 1978.

Designation of Apparent Cause of Deficiency:

The manufacturer's investigation and analysis confirmed the apparent cause of the deficiency to be an inadequate welding process where a welder or welders did not follow the proper proceJure (i.e. obtain sufficient heat during welding to obtain proper base metal penetration of the steel.)

Analysis of Safety implications:

The total number of de'icient welds was less than 1/2 of one percent of the total welds involved in the main control boards. There was no evidence of loose members or plates, or ctanges in shape and position cf the board elements and the overall structural integrity of the boards was intact. Additionally, the seismic low level verification testing which is to be done prior to operation had not yet been performed on these boards. Since the plant was still in the construction stage, seismic verification testing was yet to be performed and the deficiencies were detected and corrected prior to operation, the health and safety of the public was not affected.

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