ML19256B480
| ML19256B480 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| 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 7907120006 | |
| Download: ML19256B480 (1) | |
Text
o UNITEL STATES y
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- NUCLEAR REGULATORY COMMISSION
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SUITE 202, WALNUT CHEEK PtAZA WALNUT CREEK CALIFORNIA 94596 June 21,1979 Docket Nos. 50-275 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94105 Attention: fir. Philip A. Crane, Jr.
Assistant General Counsel Gentl emen:
Enclosed is IE Bulletin No. 79-02, Revision No.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 regarding this Bulletin or the actions required of you, please contact this office.
Sincerely, ili( 5',y L l...-_
R. H. Engelken Director
Enclosure:
IE Bulletin No. 79-02 Revision No. 1 cc w/ enclosures:
W. A. Raymond, PG&E J. D. Worthington, PG&E R. Ramsay, Diablo Canyon
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835 067 7907120006'
UNITED STATES NUCLEAR REGULATORY COM'11SSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGT0fi, 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 Circunstances:
Since the issuance of IE Bulletin 79-02 on March 8,1979, IE inspection experience and many inquiries from licensees indicate that additional informa-tion and clarification is needed. This revision is intended to serve that puroose.
None of the recuirements of the oriainal Bulleti-have been deleted, and the due date for completion of the reouested actions (July 6,1979) has not been changed. The following text supersedes the text of Bulletin 79-02.
Changes from the origiu. text are identifiad by lines in the margin. The purpose of this revision is to identify acceptable ways of satisfyina the Bulletin requirements.
While performina inservice inspections durina a March-Aoril 1978 refuelina outaae at Millstone Unit 1, structural failures rf pipina suoports for safety eouipment were observed by the licensee.
Subseq.nt licensee inspections of undamaged supports showed a larae cercentage of the concrete anchor bolts were not tiahtened properly.
Deficiency reports, in accordance with in CFP 50.55(e), filed by Lona Island Lighting Company on Shoreham Unit 1, indicate that desian 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 riaid plates.
In addition, licensee inspection of anchor brlt installations at Shoreham has shown over fifty percent of the bolt instailations to be defic'ent.
Vendor Inspection Audits by NRC at Architect Engineerina firms have shown a wide rance " 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 instal-
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lation of the bolts. -
The data available on dynamic testing of thp'
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fatigue failures can occur at loads substar cities due to material imperfections or not DUPLICATE DOCUMENT also show low cycle dynamic failures at loa g}O' Q(h due to joint slippage.
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