ML20209B806
| ML20209B806 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1987 |
| From: | Heltemes C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Layman W NUCLEAR SAFETY ANALYSIS CENTER |
| References | |
| AEOD-C701, NUDOCS 8704280519 | |
| Download: ML20209B806 (2) | |
Text
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Mr. W. Layman, Acting Director Nuclear Safety Analysis Center 3412 Hillview Avenue AE0D/C701 P. O. Box 10412 Palo Alto, California 94303
Dear Mr. Layman:
SUBJECT:
CASE STUDY REPORT -- AIR SYSTEMS PROBLEMS AT U.S. LIGHT WATER REACTORc Following resolution of peer review comments, we have completed the enclosed case study report on air systems problems at U.S. light water reactors.
The study analyzes and evaluates the operational experience related to, and the safety implications associated with failures and degradations of air system.s at U.S. LWRs.
The report presents aspects of-air systems degradations and plant responses to air systems losses which are not addressed in previous studies. It also highlights more than two dozen events in which, contrary to licensing assumptions, a safety-related system failed due to an air system degradation or failure. Operating events involving the loss or degradation of air systems were judged to be safety significant because they may lead, under different circumstances, to potentially serious events and conditions which have not been analyzed in the FSARs.
The report presents five recommendations, which, if implemented, would reduce reactor accident risks by reducing the likelihood for common mode failure of safety systems and by enhancing plant recovery from anticipated and unanticipated transients. The recommendations in the study address:
(1) ensuring that air system quality meets the requirements specified by the manufacturers of the plants' air-operated equipment; (2) ensuring adequate operator response by formulating and implementing anticipated transient and system recovery procedures for loss-of-air events; (3) improving training to ensure that plant 07erations and maintenance personnel are sensitized to the importance of air systems and the vulnerability of safety-related equipment served by the air systems to common mode failures; (4) confirming the adequacy and reliability of safety-related backup accumulators; and (5) verifying equipment response to gradual losses of air to ensure that such losses do not result in events which falPoutside FSAR analyses.
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Mr. W. Layman . As you may know, AE0D reports do not represent an official NRC position or the position of the responsible NRC program office. Our reports are one input to an ongoing review and evaluation process, and any recommendation contained in our final report will be considered and perhaps modified or eliminated by the responsible NRC office.
A copy of the case study report and this letter are being placed in the Public Document Room at 1717 H Street, N.W., Washington, D.C. 20555.
If you have any questions regarding this study, please feel free to contact me or Dr. Hal Ornstein at (301) 492-4439.
Sincerely, e,wmyesse C.J.Hamunes,&
O. J. Heltemes, Jr., Director Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated cc w/ enclosure:
G. Vine, NSAC W. Reuland, NSAC DISTRIBUTION:
PDR ;,. MWilliams AE0D CF LBell R0AB CF RDennig ROAB SF AE0D SF H0rnstein Plam KBlack WLanning FHebdon CHeltemes SRubin MChiramal PBaranowsky 0FC :ROAB R :ROAB:BC *ilEDD:DD :AEOD : :
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NAME':H0rnstein :Plam rq:SRubin [ :FH on :C temes : :
DATE :34t7/87
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- 3/h/87 :3/M/87 :3/9/87 :3/A\/87
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OFFICIAL RECORD COPY