ML19320A802

Interim Deficiency Rept Re Failure of post-tensioning Anchorheads.Generally Concurs W/Inryco 800530 Rept.All Category B Heat Treat Lots Will Be Tested.Replacement Anchorheads from Accepted Heat Treat Lots Will Be Installed

ML19320A802
Person / Time
Site:	Byron
Issue date:	06/27/1980
From:	Naughton W COMMONWEALTH EDISON CO.
To:
References
NUDOCS 8007020631
Download: ML19320A802 (2)

Text

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- /! j One F st Nabonal Plaza. Cnicago. Ilhnois Address Reply to: Post Ofhce Box 767 (kWJCJj Chicago, Illinois 60690 June 27, 1980 Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Reaion III U.S. Nuclear Regulatory Commission 799 Roosevelt. Road Glen Ellyn, IL 60137

Subject:

Byron Station Units 1 and 2 Post-Tensioning Anchorhead Failure NRC Docket Nos. 50-454 and 50-455 References (a): December 26, 1979 letter from W. F. Naughton to J. G. Keppler (b): February 29, 1980 letter from W. F. Naughton to J. G. Keppler (c): May 15, 1980 letter from W. F. Naughton to J. G.

Keppler

Dear Mr. Keppler:

Commonwealth Edison Company notified your office on November 29, 1979 of the failure of two (2) field anchorheads for the horizontal. tendons used to post-tension the concerte (primary) containment on Byron Units 1 and 2. That notification was made under 10 CFR 50.55(e). References (a), (b), and (c) contained interim reports concerning these failures, as well as two (2) additional failures.

We have reviewed the INRYCO, Inc. report entitled, " Failure Investigation of Post. Tensioning Anchorheads Used in the Byron Unit 1 Nuclear Containment Structure," dated May 30, 1980, and generally concur with-its' conclusions and recommendations. ,

However, it is Commonwealth Edison's decision to increase to 100%

the sample size for testing Category "B" heat treat lots, hence

'providing further assurance that the post-tensioning system installed in the field will perform satisfactorily. In additon, the sample size for testing Category "A" heat treat lots will be 25%

initially, increased to 50% after one rejection, and 100% after two rejections.

As testing continues, replacement anchorheads from accepted heat treat lots will be installed in the field in preparation.for resuming post-tensioning. As previously requested by members of A

%%\0-8007020 $3\ -

.7 Mr. James G. Kappler, Director June 27, 1980 Page 2 ,

your. staff, Commonwealth Edison will notify you prior to the beginning of tendon stressing at Byron Station.

One copy of the INRYCO, Inc. report is herewith enclosed, and the five (5) additional copies as requested will be forwarded under separate cover.

Please address any questions you may have to this office.

Very truly yours,

, ,/ l NWls ale-W. F. Naughton

. . _ _ Nuclear Licensing Administrator Pressurized Water Reactors Attachment' cc: Director of Inspection Enforcement 4956A s

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