ML19262B913

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Informs of Work W/Westinghouse to Define Specifics of Examination Program Re Hole Formation in Rotted Guide Thimble Tubes.Details Will Be Forwarded Before Second Cycle of Operation at Facility
ML19262B913
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 01/11/1980
From: Mills L
TENNESSEE VALLEY AUTHORITY
To: Rubenstein L
Office of Nuclear Reactor Regulation
References
NUDOCS 8001160471
Download: ML19262B913 (1)


Text

TENNESSEE VALLEY AUTHORITY CH ATTANOOGA, TENNESSEE 374o1 400 Chestnut Street Tower II January 11, 1980 Director of Nuclear Reactor Regulation Attention: Mr. L. S. Rubenstein, Acting Chief Light Water Reactors Branch No. 4 Division of Proj ect Management U.S. Nuclear Regulatory Commission Washington, DC 20555

Dear Mr. Rubenstein:

In the Matter of the Application of ) Docket Nos. 50-327 Tennessee Valley Authority ) 50-328 In my letter to you dated November 27, 1979, TVA provided responses to NRC concerns about guide thimble wear in Westinghouse fuel assemblies. These responses showed the adequacy of the guide thimble tubes based on post-irradiation observations of 14 x 14 fuel assemblies and conservative analytical extrapolations of the 14 x 14 data to 17 x 17 fuel assemblies.

In your letter dated December 14, 1979, to H. G. Parris, it was stated that the Westinghouse analysis probably accounts for all of the major variables that control the wear process, however, because of the complexities and uncertainties, the NRC believes that it would be prudent to examine an irradiated 17 x 17 assembly to verify the Westinghouse model.

TVA is working with Westinghouse to define the specifics of an examina-tion program which will demonstrate that there is no occurrence of hole formation in rodded guide thimble tubes. TVA agrees that the wear phenomenon is a time-dependent process, and, as recommended in your letter, details of the examination program will be provided to the NRC before the second cycle of operation for Sequoyah Nuclear Plant.

It is our understanding that this issue is resolved for Sequoyah's first cycle of operation until the first refueling outage.

Very truly yours, TENNESSEE VALLEY AUTiiORITY

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