ML19282B493
| ML19282B493 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 03/08/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Goodwin C PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 7903150065 | |
| Download: ML19282B493 (1) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
$ l. M.
h FIEGION V S [E ' i SUITE 202, WALNUT C REEK PLAZ A k
0 1990 N. C ALIFORNI A BOULEVARD 9
9 W ALN UT CREEK, C ALIFORNI A 94596 March 8,1979 Docket No. 50-344 Portland General Electric Company 121 S. W. Salmon Street Portland, Oregon 97204 Attention: Mr. Charles Goodwin Assistant Vice President 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, NL g
R. H. Engelken Director
Enclosures:
1.
List of IE Bulletins Issued in the past 12 months cc w/ enclosures:
B. Withers, PGE F. C. Gaidos, PGE 7903150065
UtlITED STATES fiUCLEAR REGULATORY COMMISSI0fl 0FFICE OF If1SPECTION Afl0 EflFORCEMEllT WASHIf;GTON, D.C.
20555 March 8, 1979 IE Bulletin flo. 79-02 PIPE SUPPORT BASE PLATE DESIGilS USIfiG CONCRETE EXPANSI0fl AriCHOR 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 Unit 1, indicate that design of base plates using rigid plate assumptions has resulted in underestima-tien 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 f1RC at Architect Engineering firns 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 verifica-tion 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 Classif1 cation" Revision 1, dated August 1973 or as defined in the ility was accounted for DUPLICATE DOCUMENT In lieu of supporting dity, the base plates Entire document previously entered into system under:
ANO ]TO]/Y00 3 f No. of pages: