ML19224D635
| ML19224D635 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 07/02/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 7907130205 | |
| Download: ML19224D635 (1) | |
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+,,,e W ALNUT CR LE K, CALIF OHNI A 91596 July 2, 1979 Docket tios. 50-275 50-323 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94105 At tention: Mr. Philip A. Crane, Jr.
Assistant General Counsel Gentleman:
The enclosed Bulletin 79-14 is forwarded to you for action.
Written responses are required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, ICiL n.R i -
I R. H. Engelken Direc tor
Enclosures:
1.
IE Bulletin flo. 79-14 with Appendix A 2.
Listing of IE Bulletins Issued in Last 12 Months cc w/ enclosures:
J. D. Worthington, PG&E W. Raymond, PG&E R. Ramsay, PG&E, Diablo Canyon 369 086 4
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Ut1ITED STATES f1VCLEAR REGULATORY COMMISSIOt WASHIllGT0tl, D.C.
20555 July 2,1979 IE Bulletin !!c. 79-14 SEISMIC AliALYSES FOR AS-BUILT SAFETY-RELATED PIPIf4G SYSTEMS Description of Circumstar.ces:
Recently two issues were identified which can cause seismic analysis of safety-related piping systems to yield nonconservative results.
One issue involved algebraic summation of loads in sone seismic analyses.
This was addressed in show cause orders for Beaver Valley, Fitzpatrick, Maine Yankee and Surry.
It was also addressed in IE Bulletin 79-07 which was sent to all power reactor licensees.
The other issue involves the accuracy of the information input for seismic analyses.
In this regard, several potentially unconservative factors were discovered and subsequently addressed in IE Bulletin 79-02 (pipe supports) and 79-04 (valve weights).
During resolution of these concerns, inspection by IE and by licensees of the as-built configuration of several piping systems revealed a number of nonconformances to design documents which could potentially affect the validity of seismic analyses.
ilonconformances are identified in Appendix A to this bulletin.
Because apparently significant non-conformances to design documents have occurred in a number of plants, this issue is generic.
The staff has determined, where design specifications and drawings are used to obtain input information for seismic analysis of safety-related piping systems, that it is essential for these documents to reflect as-built con-figurations.
Where subsequent use, damage or modifications affect the con-dition or configuration of safety-related piping systems as described in documents from which seismic analysis input information was obtained, the licensee must consider the need to re-evaluate the seismic analyses to con-sider the as-built configuration.
369 087
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