ML19224D633
| ML19224D633 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| 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 7907130203 | |
| Download: ML19224D633 (1) | |
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NUCLEAR REGULATORY COMMISSION
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9 SUITE 202, WALNUT CREEK PLAZA e
- ;.,, e WALNUT CREEK, CAllFORNI A 9'S96 July 2,1979 Docket tio. 50-133 Pacific Gas and Electric Company 77 Beale Street San Francisco, California 94106 Attention:
Mr. Philip A. Crane, Jr.
Assistant General Counsel 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,
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R. H. Engelken Director
Enclosures:
1.
IE Bulletin No. 79-14 with Appendix A 2.
Listing of IE Bulletins Issued in Last 12 Months cc w/ enclosures:
W. Barr, PG&E W. Raymond, PG&E E. Weeks, PG&E, Humboldt Bay 369 081 79071309D
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C.
20555 July 2,1979 IE Bulletin No. 79-14 5EISMIC ANALYSES FOR AS-BUILT SAFETY-RELATED PIPING SYSTEMS Description of Circumstances:
Recently two icsues 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 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 sJpports) 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 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.
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