ML20211J991
| ML20211J991 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 11/07/1986 |
| From: | Kane W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Opeka J NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8611140177 | |
| Download: ML20211J991 (2) | |
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MOV 0 7 W Docket No. 50-245 Northeast Nuclear Energy Company ATTN: Mr. J. F. Opeka Senior Vice President - Nuclear Engineering and Operations Group P. O. Box 270 Hartford, Connecticut 06141-0270 Gentlemen:
Subject:
Alleged Inadequacy of Pipe Break Restraints The purpose of this letter is to refer a recently received concern about the ade-quacy of certain pipe break restraints.
The specific concern is that, in 1980, modification work by Ebasco resulted in in-adequate pipe break restraints for main steam valves about three feet from the containment wall in the Millstone 1 main steam tunnel.
This reportedly resulted from the replacement of check valves in the feedwater and main steam lines with physically larger ones.
The larger valves necessitated rearrangement of the four, about two-inch diameter tension bars which paralleled the horizontal piping runs and were perpendicular to the supporting space truss and anchor structure on both sides of the check valves.
To make space for the larger valves, one end of each tension bar was displaced horizontally, and additional stress would thereby be in-troduced by the bending moment caused by a pipe break.
The basic concern is that a pipe break would stress the lugs to which the tension bars are attached beyond their yield point at the welded connection joints to tha support structure.
An additional consideration is that the tension bars themselves may be marginal in their ability to handle the stresses involved.
It was also stated that this problem was greater for the feedwater lines than for the main steam lines, and that the tension bar configuration had been modified to correct the feedwater line problem.
The individual who provided this concern to us believes this problem has not been corrected in the main steam lines.
(We re-cognize that this individual appears to be incorrect in identifying the main steam line valves close to the containment wall as check valves.)
It was also stated that this concern had not been identified to Northeast Utilities, and that it was based on calculations made without benefit of reference to the original calculations.
To enable us to determine whether additional NRC action is appropriate, we are re-questing that you review the adequacy of the pipe break restraints for the main steam line valves near the containment wall in t:1e Millstone 1 main steam tunnel.
Please provide us with your conclusions and the supporting technical basis within 30 days of receipt of this letter.
For additional information on this concern, please contact Mr. Ebe C. McCabe, Jr.,
of this office (Tel: (215) 337-5231).
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NOV 0 71985 Thank you for your cooperation.
Sincerely, Original signed By:
William F. Kane, Director Division of Reactor Projects cc:
E. J. Mroczka, Vice President, Nuclear Operations W. D. Romberg, Station Superintendent D. O. Nordquist, Manager of Quality Assurance R. T. Laudenat, Manager, Generation Facilities Licensing Gerald Garfield, Esquire Public Document Room (PDR)
Local Public Document Room (LPDR)
Nuclear Safety Information Center (NSIC)
NRC Resident Inspector State of Connecticut bcc:
Region I Docket Room (with concurrences)
DRP Section Chief M. McBride, RI, Pilgrim P. Swetland, SRI, Haddam Neck J. T. Shediosky, SRI, Millstone 3 J. Shea, LPM, NRR Robert J. Dores, DRSS A. Shropshire
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