ML19242A084
| ML19242A084 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 07/02/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Short T OMAHA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7907310212 | |
| Download: ML19242A084 (1) | |
Text
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July 2, 1979 Docket No.
50-285 Omaha Public Power District ATTN:
T. E. Short, Assistant General Manager 1623 Harney Street Omaha, Nebraska 68102 Centlemen:
The enclosed IE Bulletin 79-14 is forwarded to you for action. Written responses are required.
If you desire additional inforcation regarding this matter, please contact this office.
Sincerely,
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'Karl V. Seyfrit Director
Enclosures:
1.
List of IE Bulletins Issued in Last Twelve Months cc:
R.
L. Andrews, Manager
" ort Calhoun Station Post Offica Box 98 Fort Ca'.houn, Nebrc s.a 68102 7907310212
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UNITED STATES NUCLEAR llEGULATORY C0rNISSION WASHINGTON, D.C.
20555 IE Bulletin No. 79-14 Date:
July 2, 1979 Page 1 of 3 SEISMIC ANALYSES FOR AS-BUILT SAFETY-RELATED PIPING SYSTEBIS Description of Circumstances:
Recent.ly 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 seismi.c 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) ind 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 docta.ents have occurred in a number of plants, this issue is generic.
The staf f has determined, where design specifications and drawings are used to obtain input information for seis.nic 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 m.ist consider the need to re-evaluate the seismic analyses to con-sider the as-built configuration.
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