ML19273B220
| ML19273B220 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/08/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7904040353 | |
| Download: ML19273B220 (1) | |
Text
nr004 UNITED STATES NUCLEAR REGULATORY COMMISSION
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March 8, 1979 Docket Nos. 50-317 50-318 Baltimore Gas and Electric Company ATTN: Mr. A. E. Lundvall, Jr.
Vice President, Supply P. O. Box 1475 Baltimore, Maryland 21203 Gentlemen:
The enclosed IE Bulletin No. 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,
/
k W-
[ Boyce H. Grier r " Director
Enclosures:
1.
Listing of IE Bulletins Issued in Last Twelve Months cc w/encls:
R. M. Douglass, Manager, Quality Assurance L. B. Russell, Chief Engineer W. Gibson, General Supervisor, Operations QA R. C. L. Olson, Senior Engineer K. H. Sebra, Principal Engineer 790404 0 3 6 3
A, UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND NFORCEMENT WA:HINGTON, 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 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 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 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" the applicable FSAR.
1.
Verify that pipe DUPLICATE DOCUMENT in the calculati analysis justifyi Entire document previously entered into system under:
ODO ANO No. of pages:
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