ML19199A218
| ML19199A218 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/20/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7904050021 | |
| Download: ML19199A218 (1) | |
Text
e UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Bulletin No. 79-02 Date: March 8, 1979 Page 1 of 3 PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
While performing inservice inspections during a March-April 1978 refueling outage at Millstone Unit 1, structural failures of piping supports for safety equipment were observed by the licensee.
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, 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 installations at Shoreham has shewn 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 installation 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 capacities due to material imperfections or notch type stress risers. The data also show low cycle dynanic failures at loads below the bolt static capacities due to joint slippage.
Action to be Taken by Licensees and Pennit Holders:
For pipe support base plates that use concrete expansion anchor bolts in Seismic Category I systems as defined by Regulatory Guide 1.29, " Seismic Design Classi#ication" Revision 1, ("^" """" " ~ AdfL"A41-the applicable FSAR.
DUPLICATE DOCUMENT 1.
Verify that pipe support base in the calculation of anchor Entire document previously entered analysis justifying the assum into system under:
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KING OF PRUS$1 A, PENNSYt V ANI A 19406 March 20, 1979 Docket Nos. 50-289 50-320 Metropolitan Edison Company ATTli: Mr. J. G. Herbein Vice President - Generation P. O. Box 542 Reading, Pennsylvania 19640 Gentlemen:
The enclosed IE Circular 79-05 is forwarded to you for information.
A written response is not required.
If there are any questions related to your understanding of the suggested actions, please contact this office.
Sincerely, AL oyce H. Grier Director
Enclosures:
1.
IE Circular No. 79-05 2.
List of IE Circulars Issued in Last Twelve Months cc w/encis:
E. G. Wallace, Licensing Manager J. J. Barton, Project Manager R. C. Arnold, Vice President - Generation L. L. Lawyer, Manager - Generation Operations G. P. Miller, Manager - Generating Station - Nuclear J. L. Seelinger, Unit 1 Superintendent W. E. Potts, Unit 1 Superintendent - Technical Support J. B. Logan, Unit 2 Superintendent G. A. Kunder, Unit 2 Superintandent - Technical Support I. R. Finfrock, Jr.
Mr. R. Conrad G. F. Trowbridge, Esquire Miss Mary V. Southard, Chairman, Citizens for a Safe Environment 790405oCet g.g