ML19282B436
| ML19282B436 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 03/08/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7903150015 | |
| Download: ML19282B436 (1) | |
Text
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I' 7 Bro c,8 *%,k UNITED STATES 7
NUCLEAR REGULATORY COMMISSION f.g NI _h REGION lli 799 ROOSEVELT ROAD g
,6y GLEN E LLYN, ILLINolS 60137 MR -8.1979 Docket Nos. 50-10, 50-237, 50-249, 50-254, 50-265, 50-295, 50-304, 50-373, 50-374,40-454, 50-455, 50-456, 50-457 Commonwealth Edison Company ATTN:
Mr. Byron L2e, Jr.
Vice President P. O. Box 767 Chicago, IL 60690 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,
/Di James G. Keppler n rector
Enclosures:
1.
List of IE Bulletins Issued in Last Twelve Months cc w/encls:
Mr. B. B. Stephenson, Mr. R. Cosaro, Project Station Superintendent Superintendent Mr. N. Kalivianakis, Central Files Station Superintendent Director, NRR/DPM Mr. N. Wandke, Station Director, NRR/ DOR Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Anthony Roisman, Esq.,
Mr. R. H. Holyoak, Station Attorney Superintendent Mr. Dean Hansell, Office Mr. Gunner Sorensen, Site of Assistant Attorney Project Superintendent General 7903150015
8 a
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMFNT REGION III March 8, 1979 IE Bulletin No. 79-02
~.
PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS h
Description of Circumstances:
While performing inservice inspections during a March-April 1978 refueling outage at Millstone Unit 1, structural feilures 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 assumptions 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 plates. In addition, licensee inspection of anchor bolt installations at Shoreham has shown over fifty percent of the bolt installations to be deficient.
Vendor Inspectfen 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 fatiguc failures can occur at loads substantially below the bolt static capacities due to material imperfections or notch type stress l
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:
4 For pipe support base plates that use concrete expansion anchor bolts in Seismic Category I systems as defined by Regulatory Guide 1.29. " Seismic j
Design Classification" Revision 1, dated August 1973 or as defined in the applicable FSAR.
Veri,fythatgpe_suppor,tyse,plaeyexipility.wasaccountedfor 1.
u ir of supporting
%j he base plates a
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