ML19261C078
| ML19261C078 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 03/08/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Clayton F ALABAMA POWER CO. |
| References | |
| NUDOCS 7903140532 | |
| Download: ML19261C078 (1) | |
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noatCo UNITED STATES
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NUCLEAR REGULATORY COMMISSION j
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MAR 8 1979 In Reply Refer To:
RII:3PO 50-348 50-364 Alabama Power Company Attn:
Mr. F. L. Clayton, Jr.
Senior Vice President Post Office Box 2641 Birmingham, Alabama 35291 Gentlemen:
The enclosed Bulletin 79-02 is forwarded to you for action. A written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, uf.O' ames P. O'Reilly D ector
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Enclosure IE Bulletin No. 79-02 7903140 5 3 &
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MAR 8 1979 Alabama Power Company,
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Mr. W. G. Hairston, III Plant Manager
~ Drawer 470 Ashford, Alabama 36312 Mr. R. E. Hollands, Jr.
QA Supervisor P. O. Box U Ashford, Alabama 36312 l
Mr. A. R. Barton Executive Vice President Post Office Box 2641 Birmingham, Alabama 35291 Mr. H. O. Thrash, Manager Nuclear Generation Post Office Box 2641 Birmingham, Alabama 35291 Mr. C. Biddinger, Jr., Manager Corporate Quality Assurance Post Office Box 2641 Birmingham, Alabama 35291 b
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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 8, 1979 IE Bulletin No. 79-02 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 concrere 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 resulred in underestima-tion of loads on some anchor bolts. Initial investigatiou indicated that nearly fif ty 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 r.hown over fif ty 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 concrcte 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 dynamic failures at loads below the bolt static capacities due to joint slippage.
Action to be Taken by Licensees and Permit 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 Classification" Revision 1, dated August 1973 or as defined in the applicable FSAR.
1.
Verify that pipe support base plate flexibility was accounted for in the calculation of anchor bolt loads.
In lieu of supporting analysis justifying the assumption of rigidity, the base plates 1 of 3