ML20002C720

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Responds to Util 721109 & 1206 Ltrs Re AEC Re Valve Wall Thickness Verification Program.Requests Addl Info Re Sampling Plan Failure Probability & Level of Confidence Involved,Valve Listings & Design Pressure Ratings
ML20002C720
Person / Time
Site: Big Rock Point, Palisades  File:Consumers Energy icon.png
Issue date: 12/27/1972
From: Grier B
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To: Haueter R
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
Shared Package
ML20002C721 List:
References
NUDOCS 8101100784
Download: ML20002C720 (2)


Text

.

UNITED STATES ATOMIC ENERGY COMMISSION

,.3 DIRECTORATE OF REGULATORY OPERATIONS s / '

.h REGION lil

  1. '8 tis 5' p 799 ROOSEVELT ROAD TrtzrHoNE GLEN ELLYN, ILLINOIS 6o137 (312)858-2660 December 27, 1972 Consumers Power Company Docket No. 50-155 ATIN:

Mr. Robert L. Haueter Docket No. 50-255 Electric Production Superintendent - Nuclear 212 West Michigan Avenue Jackson, Michigan 49201 Gentlemen:

Thank you for your letter of November 9, 1972, in response to our letter dated September 13, 1972, and your supplemental letter, dated Decenter 6, 1972, which you have provided to clarify certain questionable aspects of your November 9 letter.

We have reviewed both of the above identified letters as they relate to the adequacy of the prograc! you plan to implerent to assure that certain valves in your Big Rock Point and Palisades Plants meet vall thickness requirements. Our review of your planned valve wall thickness verification program has been based on the guidelines contained in our letter of June 29, 1972, and a second letter, dated September 13, 1972, and we coteent as follows:

With respect to your plans for the Palisades Plant, you apparently intend to determine the adequacy of valve wall t'aicknesses on a sampling basis and have identified a saeple size of about 30 percent, insofar as the total number of valves is concerned, and a minicum sample size of about 12 percent relative to types of valves and manufacturers. While a sampling plan may be an acceptable approach, the method of sample selection, sanple size, acceptance levels, and analysis of results of measurement activities become critical factors. Consequently, please provide us with additional infor-mation, in writing, within 30 days, which relates to:

(1) the probability of failure of the sampling plan to identify a thin i

wall valve, and (2) the level of confidence involved.

Concerning your cosaments relative to the Big Rocic Point Plant, 1.e., the last two paragraphs of your November 9 letter, it is necessary that we receive additional information, in writing, within 30 days, in order to implement our evaluation of your position in this matter. This information should include, but I

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Consurers Tower Company December 27, 1972 not be limited to:

(1) a listing of the valves Civolved based on the contents of our June 29, and September 13, 1972, letters.

(2) identification of the design pressure rating and highest anticipated operatint pressure for each of these valves, and (3) an analysis of valve design pressure ratinr. versus highest anticipated operatinE pressure for each valve which can be evaluated in tert.s of the maximum amount of reduced wall thickness that could be accomnodated by desirn overpressure considerations.

Your cooperation with us in this matter is appreciated.

Sincerely yours, Boyce H. Crier Regional Director Ralph B. Seve11, Nuclear ec:

Licensinr Administrator bec w/1trs dtd 11/9/72 and 12/6/72:

R0 Chief, RT60B R0 Chief, RCB RO:HQ (4)

Licensing (4)

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