ML20024G342
| ML20024G342 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 01/22/1973 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wachter L NORTHERN STATES POWER CO. |
| Shared Package | |
| ML20024G343 | List: |
| References | |
| NUDOCS 9102110333 | |
| Download: ML20024G342 (2) | |
Text
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g UNITED STATES
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I ATOMIC ENERGY COMMISSION i
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DIRECTOR ATE OF REGULATORY OPERATIONS d-9 ## f u l' 'c REOlON lli A
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799 ROOSCVELT ROAD I
yrgfgggg GLEN CLLYN, ILLINOIS 60137 (812)ess 2660 l
January 22, 1973 I
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Northern States Power Company Docket No. 50-263 ATTN Hr. Lao Wachter, Vice President Power Production 414 Nicollet Mall Hanneapolis, Minnanota 55401 Cantlement f
Thank you for your letter of November 3,1972, in response to our letters 1
dated June 29 and Septenber-13, 1972, all dealing with a program to verify that valves important to nuclear safety have wall thicknesses consistent with the minimum requirements specified by the applicable codes, standards, and procurement specifications.
t We have reviewed your detailed measurement progran plans and conclude that all of the couaitmente contained in your August 8 letter on this matter are being implemented except that, in paragraph three of your August 8 letter, you refer to a..." statistical sample of the valve type and manufactur6.
This could mean that you intend to use s l
l statistical sampling ; tan, as opposed to actual isessurement of each of the valves involved. While a statistical sampling plan may be an i
acceptable approach, the method of sample selection, aanple else, i
acceptance-rejection levels, and analysis of results of measurement t
activities become critical factors.
If you intend to use a sampling plan, please provide us with additional information, in writing, within 30 days, which relates tot (1) the basic eler.ents of the sampling plan, (2) the probability of failure of the sampling plan
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Northern States Power Company 2-January 22, 1973 i
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to identify a thin vall valve, and (3) the level of confidence involved.
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If you have questions regarding this utter we will be sled to discuse them with you.
Sincerely yours, i
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Boyce H. Crier
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Regional Director i
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