ML19282B452
| ML19282B452 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 03/08/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7903150025 | |
| Download: ML19282B452 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION
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Docket No. 50-358 Cincinnati Gas and Electric Company ATTN:
Mr. Earl A. Borgmann Vice President Engineering Services and Electric Production 139 East 4th Street Cincinnati, OH 45201 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, A,.Keppler[a. b ames G Director
Enclosures:
1.
IE Bulletin No. 79-02 2.
List of IE Bulletins Issued in Last Twelve Months cc w/encls:
Mr. J. R. Schott, Plant Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC U. Young Park, Power Siting Commission Citizens Against a Radioactive Environment 7903150025
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U.S. NUCLEAR REGULATORY COMHISSION OFFICE OF INSPECTION AND ENFORCEMENT
- AEGION III 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 support 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 Unit 1, indicate that design of base plates using rigid plate assu=ptions has resulted in underestima-tion of loads on some anchor bolts. Initial investigation indicated that near.ly fifty percent of the base plates could not be assumed to behave as rigid pistes. In addition, licensee inspection of anchor bolt installations at Shotsham 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 a. dor 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.
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