ML19290E977

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Interim Status Rept Re out-of-tolerance Threads for NSSS Lateral Support Anchor Bolt Nuts.Results of Tests of Diameter Nuts Being Analyzed.Unable to Conclude Reportability of Incident Until Nut Strength Is Evaluated
ML19290E977
Person / Time
Site: Wolf Creek Wolf Creek Nuclear Operating Corporation icon.png
Issue date: 03/05/1980
From: Koester G
KANSAS GAS & ELECTRIC CO.
To: Seidle W
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
NUDOCS 8003170412
Download: ML19290E977 (2)


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Q ussas ans ano wcmc cOmar GLENN L. m O E ST E R me. ....................

March 5, 1980 Mr. W.C. Seidle, Chief Reactor Construction and Engineering Support Branch-U.S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 Rc: STN 50-482 Subj: Interim Status Report - NSSS Lateral Snpport Anchor Nuts

Dear Mr. Seidle:

The purpose of this letter is to supplement our previous notification of December 27, 1979, to you concerning difficulties experienced at the Wolf Creek Site with out-of-tolerance threads for the NSSS lateral support anchor bolt nuts. In that notification you were advised that additional inspections and analyses of selected anchor bolt nuts would be initiated in order to fully determine che extent and scope of these difficulties and, further, to assess the safety significance of this matter pursuant to 10CFR50.55(e) regulations. A follow up report by March 1, 1980 was indicated e.t that time.

Follow-up studies have s:*nce been initiated involving representative samples of nonconforming nuts identified at the two SNUPPS jobsites.

To date over 900 1/2 inch diameter nuts have been inspected and pertinent out-of-tolerance conditions identified for further analyses.

Three such nuts, representing worst care conditions identified between the two jobsites, have been tested at Lehigh University in accordance with test procedures approved by Bechtel Power Corporation. The results of these tests are currently being analyzed and will be compared with maxi-mum bolt loads being calculated for a given support structure. Based upon these analyses, efforts will also be made to correlate analytical and e=pirical test data in order to more precisely establish methods for determining the strength of the threads on the nut. This effort is expected to be complete on or about June 1, 1980. Until this effort is complete, we are unable to conclude whether the described difficulties represent a Signi.ficant Deficiency as defined in 10CFR50.55(e) .

Upon completion of the studies indicated above, you will be advised of additional follow-up actions required, as well as our conclusions regarding

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201 N. Market - Wuchsta. Kansas - Mail Address: P.O. Box 208 / Wichita. Kansas 67201 - Teleonone: Area Code (316) 261-6451

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Mr. W,C. Seidle March 5, 1980 the safety significance and reportability of this matter. In the event this item cannot be satisfactorily resolved by June 1st, an additional interim status report will be prepared and forwarded to you.

Very truly yours, t

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Q Glenn L. Koester Vice President - Operations GLK:bb