ML20138L134
| ML20138L134 | |
| Person / Time | |
|---|---|
| Issue date: | 12/10/1985 |
| From: | Ward D Advisory Committee on Reactor Safeguards |
| To: | Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| References | |
| ACRS-R-1171, NUDOCS 8512190174 | |
| Download: ML20138L134 (1) | |
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION o
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 1%..... * ',8.
WASHINGTON, D. C. 20555 December 10, 1985 Mr. William J. Dircks Executive Director for Operations U. S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Dircks:
SUBJECT:
ACRS COMMENTS REGARDING POTENTIAL UPGRADE OF AUXILIARY FEEDWATER SYSTEMS IN CERTAIN OPERATING PLANTS During its 308th meeting on December 5-7, 1985, the ACRS discussed the issue of reliability of auxiliary feedwater (AFW) systems *
~~ rating pressurized water reactors.
This matter was also discussed at e Sub-connittee meeting on Decay Heat Removal Systems on December 2, 1965.
During the Subcommittee meeting, representatives from the NRC Staff discussed the evolution of reliability requirements for these systems, information that is available on actual performance, and the program to complete the review of reliability estimates for the AFW designs in older plants.
The Subcommittee also heard a report of a recently developed analyt' cal method for assessing common cause failures in multitrain AFW systems.
We believe the issue of AFW reliability is important and deserves the continuing attention of the NRC Staff on a high-priority basis. We are concerned about the timely resolution of this issue, especially for older operating plants.
The NRC Staff was unable to articulate a specific resolution schedule for the concern about AFW reliability at several older plants.
We believe a finn plan and schedule should be developed expeditiously.
Although there have been hundreds of system-years of operating experi-ence, the data needed for a statistical evaluation for comparison with the theoretical reliability predictions have not been available in a readily useful form.
Such an analysis is complicated further by the fact that AFW system design and use differs from plant to plant.
An event that constitutes a challenge to the system in one plant might not be a challenge in another. We believe a stronger effort to assemble and analyze AFW operational experience should be undertaken.
Sincerely, David A. Ward Ninun
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