ML18037A234

Interim Deficiency Rept Re Weld of Biological Shield Wall Base Ring to Outer Shell Plate.Defects Discovered in Horizontal Stiffener to Inner Shell Plate Welds of Ring 3. Metallurgical Analysis Underway.Final Rept Available 800331

ML18037A234
Person / Time
Site:	Nine Mile Point
Issue date:	01/15/1980
From:	Terry J NIAGARA MOHAWK POWER CORP.
To:
References
NUDOCS 8001230191
Download: ML18037A234 (6)

Text

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SUBJECT:

Interim deficiency rept .re weld of biological shield wall base iing 'to'uter shell plate, Defects discoveredof-'ing 'in horizonta,1 stiffener to inner shell plate welds

,d, 2.,

3, Metallurgical analysis underway. Final iept available 800331 DISTRIBUTION CODE ~ B019$ COPIES RKCKIVEDiLiTR ~ ENCL'IZE:

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NIAGARA MOHAVIKPOVIER CORPORATION/300 ERIE 80ULEVARD O'EST. SYRACUSE, N.Y. 13202/TELEPHONE (315) 474.1511

'anuary 15, 1980 Office of Inspection and Enforcement Region I Attention: Mr. R. T. Carlson, Chief Reactor Construction and Engineering -"

Support Branch U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Dear Mr. Carlson:

Re: Nine Mile Point Unit 2, Docket No. 50-410 A potential significant deficiency involving the Biological Shield llall base ring to outer shell plate .weld was previously reported to Mr. L. Narrow of your staff on May 30, 1979. The investigation and resolution of this problem has not been 'completed. Consequently a final report on, this subject will not be available until March 31, 1980. This letter serves as an interim report.

The results of the metallurgical analysis which were discussed in our September 18, 1979 letter are now in the final stages of being compiled and will be provided in our final report.

The status of the Biolooical Shield wall investigation is summarized as fol 1ows:

1. As reported in our September 18, 1979 report, the base ring to outer weld has been 100 percent re-examined and reworked as required. 'hell

2. The inner wall to base plate welds have been 100 percent re-examined and reworked as required.

3. The cover plate to stiffener welds for Rings 1 and 2 are being 100 percent re-examined and reworked as required.

4. Defects have been discovered in the horizontal stiffener to inner shell plate welds of Ring 3. Due to the inaccessibility of these welds, it is difficult to determine the extent of the defects QggP.

Therefore, Niagara Mohawk is investigating the most effective alternatives to resolve this matter.

/D 800>S30 i'tt .

L

An independent consultant was contracted to conduct. a metallurgical evaluation of the welds in the Biological Shield Wall. To aid in, this evaluation a metallurgical analysis has been performed on two sample horizontal stiffenei to inner shell plate welds removed from Ring 3.

P I

As indicated above, a final report summarizing our tests and analyses and identifyng any safety implications will be provided by March 31, 1980.

Very truly yours, N1AGARA MOHAWK POWER CORPORATION Joh . erry Senior Vice President

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