ML20003A333
| ML20003A333 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 01/29/1981 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, NUDOCS 8102030508 | |
| Download: ML20003A333 (3) | |
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January 29, 1981 United States Nuclear Regulatory Commission Region I 631 Park Avenue King of Prussia, PA 19406 Attention:
Mr. Boyce H.
Grier Director Gentlemen:
SUBJECT:
Beaver-Valley Power Station Unit NO. 2 Docket No. 50-412 Final Report - Inferior Welds on Cable Tray Fittings Significant Deficiency Report No. 80-05 Enclosed is a copy of our Final Report - Interior Welds on Cable Tray Fittings.
This report is in reference to the poten-tially reportable deficiency concerning the welds under the pro-visions of 10CFR50.55 (e) (1) (i), (ii) and (iv) about which you were advised in our interim report forwarded with our letter -dated November 14, 1980.
A preliminary inspection of the factory procedures for repairing the fittings was reviewed by Stone & Webster and D.L.Co.
Vendor Surveillance Group personnel and the approach was found to be satisfactory.
DUQUESNE LIGHT COMPANY By:
M jg E.f J. Woolever Vice President Enclosure cc: Messrs.
V.
Stello (15)
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Jabbour 11 a
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FINAL REPORT INFERIOR WELDS ON CABLE TRAY FITTINGS BEAVER VALLEY POWER STATION - UNIT NO. 2 DUQUESNE LIGHT COMPANY Summary Rungs welds of poor quality were found on a number of cable tray
" tees" and " crosses" inspected in the field.
Field -inspection i ;rther disclosed that, when performing the rung welding,.the vendor 4
(T. J. Cope) did not adhere to his own detail drawings, which were reviewed and approved by S&W.
The fittings, some of which were installed, are'used in safety-related cable tray _-systems.
4 Immediate Action Taken A "Stop Work" order was issued to hold. installation of all remaining safety-related cable tray fittings (" tees" and " crosses" only)..No action was taken regarding f actory inspection at the time, because all trays - ordered -had been shipped to the jobsite before the deficiency was discovered.
Deficiency During a recent site inspection conducted by an NRC -inspector,
several installed cable tray. fittings were noted as having rung welds that appeared to be of poor-. quality.
Subsequent to the NRC 'in-
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spectors visit, several S&W engineers inspected-both' installed and uninstalled " tees" and " crosses" and found that a number of' welds 3
were deficient for the following reasons:
1.
Excessive porosity 2.
Discontinuities It was further determined that.the-vendor deviated from' approved
- detail drawings. when fabricating the.. fittings.
Deviations. were noted as follows:
1.
Rungs were welded on both sides'of back plate'instead'of the outside only, as shown on the drawings and, 2.
The third rung in from each end of the " tee" fittings was welded to'the back plate,-not swaged as shown on the drawings.
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Analysis of Safety Implications It was determined that a structural failure of one or more rung welds during a seismic event was possible because of the poor quality welds.
Should this occur it is possible that safety-related cables routed in the tray may be damaged as a result of the relative novement between the rungs and the side rails which could then occur during the seismic disturbance.
Failure of the welds could leave sharp edges on both the rung ends and the side rails that could abrade cable jacke and insulation systems causing circuit grounds and/or short circu.:s and subsequent failure of safety-related circuits.
Since these fittings are used on both safety-related-trains, safe opera-tion of the unit could be compromised.
Corective Action to Remedy Deficiency S&W determined that certification of tray fitting adequacy to sustain a seismic event without rung weld failure, by either test or analysis, was problematic.
The randomness of rung weld deficiences made selection of a representative sample extremely difficult.
Consequently, all tray " tees" and " crosses" installed in safety-related areas were removed and will be returned to the vendor, along with the uninstalled fittings, for either repair or replacement to ensure the structural adequacy of the rung welds during a seismic event.
The following steps have been taken to monitor the vendors per-formance of the repairs / replacement:
1.
The specification has been revised to require D.L.Co. 's shop inspector to visually inspect each weld located at the inter-section of the rung and the inside face of the side rail, prior to galvanize touch-up, so that an accurate asssessment of weld conformance to the specified criteria can be made. All welds at
.this intersection will be inspected.
2.
The vendor has revised his detail drawings to reflect his latest fabrication procedures and resubmitted them to S&W for approval.
D.L.Co. 's shop inspector will verify that the fittings conform to the latest drawings which are now approved.
A preliminary inspection of the f actory procedures for repairing the fittings was reviewed by S&W and D.L.Co. Vendor Surveillance Group personnel and the approach was found to be satisfactory.
Fitting repair is' now proceeding on a production basis and is expected to be completed by April 1, 1981.
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