ML19256B481
| ML19256B481 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 06/21/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7907120008 | |
| Download: ML19256B481 (1) | |
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UNITED STATES Eg','y'n NUCLEAR REGULATORY COMMISSION O
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i VJA NUT CR E E K, CA LIFORNI A 94596 June 21,1979 Docket No. 50-133 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentlemen:
Enclosed is IE Bulletin No. 79-02, Revision flo.1, which requires action by you with regard to your power reactor facility (ies) with an operating license or a construction permit.
Should you have questions regardino this Bulletin or the actions required of you, please contact this office.
Sincerely, f(i.( h,c i...
R. H. Engelken Director
Enclosure:
IE Bulletin flo. 79-02 Revision No. 1 cc w/ enclosures:
W. Barr, PG&E W. A. Raymond, PG&E E. Weeks, PG&E, Humboldt Bay
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836 069 7907120007
UNITED STATES NUCLEAR REGULATORY COMMISSIO:1 0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 June 21, 1979 IE Bulletin No. 79-02 (Revision No. 1)
(7906200183)
PIPE SUPPORT BASE PLATE DESIGNS USING CONCRETE EXPANSION ANCHOR BOLTS Description of Circumstances:
Since the issuance of IE Bulletin 79-02 on March 8, 1979, IE insJection experience and many inquiries from licensees indicate that addi'ional informa-tion and clarification is needed. This revision is intended to serve that puroose. None of the requirements of the original Bulletin have been deleted, and the due date for completion of the requested actions (July 6,1979) has not been changed.
The following text supersedes the text of Bulletin 79-02.
Changes from the original text are identified by lines in the margin. The purpose of this revision is to identify acceptable ways of satisfyino the Bulletin requirements.
While performing inservice inspections during a March-Aoril 1978 refuelina outace at Millstone Unit 1, structural failures of pipina 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 tiqhtened properly.
Deficiency reports, in accordance with 10 CFR 50.55(e), filed by Lona Island Lighting Company on Shorehan Unit 1, 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 ricid 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 Engineerinq firms have shown a wide range of design ractices and installation procedures which have been employed for the use of concrete expansio1 anchors.
The current trends.in the industry are toward more rigorous controls and verification of the instal-lation of the bolts.
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fatigue failuras can occur at loads sub" DUPLICATE DOCUMENT cities due to material imperfectiors or i gd 3 0 0,70
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also show low cycle dynamic failures at Entire document previously entered due to joint slippage.
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