ML19224D640
| ML19224D640 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/02/1979 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Johari Moore SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| NUDOCS 7907130216 | |
| Download: ML19224D640 (1) | |
Text
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SUITE 202, WALNU T CHE E K PLAZA WALNUT CREE K, CALIFORNI A 94596 July 2, 1979 Docket tios. 50-361 50-362 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 31770 Attention: fir. J. B. Moore Vice Presidant Gentlemen:
The enclosed Bulletin 79-14 is forwarded to you for action.
Wri tten responses are required.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
}ltii. n < f....-
R. H. Engelken Director
Enclosures:
1.
IE Bulletin tio. 79-14 with Appendix A 2.
Listing of IE Bulletins Issued in Last 12 Months cc w/ enclosures:
J. H. Drake, SCE M9 094 T 9 0 71;7 (y29
s' UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C.
20555 July 2,1979 IE Bulletin No. 79-14 SEISMIC ANALYSES FOR AS-BUILT SAFETY-RELATED PIPING SYSTEMS Description of Circumstances:
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 some seismic analyses.
This was addressed in show cause orders for b yer Valley, Fitzpatrick, Maine Yankee and Surry.
It was also addressed in IE Bulletin 79-07 which was sent to all pcwer reactor licenrees.
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.
Nonconformances 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.s-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.
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