ML19224D504
| ML19224D504 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 06/21/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7907120373 | |
| Download: ML19224D504 (1) | |
Text
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June 21, 1979 Docket No.
50-298 Nebraska Public Power District ATTN:
J. M. Pilant, Director Licensing & Quality Assurance Post Office Box 499 Columbus, Nebraska 68601 Gentlecen:
Enclosed is IE Bulletin No. 79-02, Revision No. 1, which requires action by you with regard to your power reactor facility with an operating license or a construction permit.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely, 1
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tarl V. Seyfri.
Direc to r
Enclosures:
1.
IE Bulletin No. 79-02 Revision No. 1 2.
List of IE balletins Issued in last Twelve Montr.s cc:
L. C. Lessor, Superintendent Cooper Nuclear Station Post Office Box 98 Brownville, Nebraska 65321 9007120373
UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF IhSPECTION AND EYFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 79-02
~(Revision No. 1)
Date: June 21, 1979 Page 1 of 6 PIPE SUPPORT BASE PLATE DE3IGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
Since the issuance of IE Bulletin 79-02 on March 8, 1979, IE inspection experience and many inquiries from licensees indicate that additional informa-tion and clarification is needed.
This revision is intended to serve that purpose.
None of the requirements of the original Bulletin have been deleted, and the due date for completion of the requested actions (July 6, 1979) has not been changed. The following text supersedes the text of Bulletin 79-02.
Changes from the original text are identified by liues in the margin.
The purpose of this revision is to identify acceptable ways of satisfying the Bulletin requirements.
While performing inservice inspections during a March-April 1978 refueling outage at Millstone Unit 1, structural failures of piping supports for safety equipment were obser%d'by the.icensee.
Subsequent licensee inspections of undamaged supports showed a large percentage of the concrete anchor bolts were not tightened properly.
Deficiency reports, in accordance with 10 CFR 50.55(e), filed by Long Island Lighting Company on Shoreham Unit 1, indicate that design of base plates using rigid plate assumptions has resulted in underestimation of loads on some anchor bolts.
Initial investigation indicated that nearly fifty percent of the base plates could not be assumed to behave as rigid plates.
In addition, licensee inspection of anchor bolt installa; ions at Shoreham M shown over fifty percent of the bolt installations to be deficient.
Vendor Inspection Audits by NRC at Architect Engineering firms have shown a wide range of design practices and installation procedures which have been employed for the use of concrete expansion anchors. The current trends in the industry are toward more rigorous controls and verification of the instal-lation of the bolts.
The data available on dynamic testing of the concrete expansion anchors show fatigue failures can occur at loads substantially below the bolt static capa-cities due to material imperfections,+ - W
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also show low cycle dynamic failured
'1 due to joint slippage.
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