ML19260B974

Confirms Verbal Rept Re Noncompliance to Specs for Nuclear Valves.Caused by Error in Computer Program,Developed by Subcontractor.All Reported Frequencies Will Be re-analyzed

ML19260B974
Person / Time
Site:	Grand Gulf
Issue date:	11/12/1979
From:	Niehaus P WILLIAM POWELL CO.
To:
References
REF-PT21-79-168-000 NUDOCS 7912180054
Download: ML19260B974 (2)

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THE WM. POWELL COMPANY 2503 Spring Grove Avenue P.O. Box 14006. Cincinnati, Ohio 45214, U.S.A.

uY 513/852-2000 November 12, 1979 United States Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive Suite 1000 Arlington, Texas 76012 Attention: Mr. K.V. Seyfrit, Director

Reference:

Phone conversation of 11/9/79 between Mr. Edwin E. Winterfeldt and Mr. Joe Loftus of Powell and Mr. Ramon Hall, Duty Officer, NRC.

Dear Mr. Seyfrit:

The following is a confirmation of a verbal report in accordance with NRC Regu-lation 10CFR Part 21 of a noncompliance to specifications for nuclear valves sucplied by the Wm. Powell Company to the Mississippi Power and Lignt Co.,

Grand Gulf Nuclear Station, Units 1 and 2, Port Gibson, Mississippi 39150. This nuclear plant is still under construction and therefore, is not in operation. The noncompliance was verified to exist by the Wm. Powell Company on November 9, 1979.

We have supplied Mississippi Power and Light with Class 1, 2, and 3 valves which were, by design specification, to have a minimum natural freq.2ncy of 33 hertz.

In the process of reviewing the pcssibility of recertifying these valves to have a minimum natural frequency of 100 hert:, in accordance with a Sechtel procosed specificaticn change, !! was discovered that the original calculations were in error. We have determined that the error lies in a computer program which was develcped by one of our subcontractors.

We find that this error is not of a fixed magnitude, nor does it disqualify all valves supplied. The error magnitude is dependent upon the geometry of each valve and therefore, necessitates a reanaiysis of aach qualifying seismic report for this customer. The valves, we know today, that fall below the specification require-ment are cylinder coersted 8 and 10" figure 1503, Sechtel item numbers 1 A.11 A through F ,14.21 A through D, and 14.10 A thecush D, supplied against Sechtel specification 945-M-242.0.

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November 12, 1979 Page 2 The Wm. Powell Company's Engineering Department has initiated a project to reanalyze all reported frequencies. This activity is expected to continue for the next six weeks.

The Wm. Powell Company has notified Bechtel Corporation, engineers for Mississippi Power and Light Company, of the above situation and will continue to notify them as additional information is obtained.

Sincerely, THE WM. POWELL COMPANY i a V.P. , Mf g. & Engineering

- PWN/Ir Three copies to: Director, Office of inspection and Enforcement U.S. Nuclear Reculatory Commission Washington, D.C. 20555

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