ML20198P030
| ML20198P030 | |
| Person / Time | |
|---|---|
| Issue date: | 01/15/1998 |
| From: | Rossi C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Drake A WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9801210306 | |
| Download: ML20198P030 (2) | |
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January 15, 1998 Mr. Andrew Drake, Project Manager Westinghouse Owners Group Westinghouse Electric Corporation Mail Stop ECE 516 P.O. Box 355 Pittsburgh, PA 15230-0355
Dear Mr. Drako:
SUBJECT:
AUXILIARY / EMERGENCY FEEDWATER SYSTEM RELIABILITY STUDY Enclosed are two ccgles of a draft report,? Auxiliary / Emergency Feedwater System Reliability, 19871995," INEEUEXT 97 00740. The objective of this study was to assess auxiliary i
feedwater system performance in 72 PWRs based on operating experience from 19871995 1
Major findings of the study include the following:
Based on the 19871995 experience data, there were no failures of the entire system identified in 1,117 unplanned system demands.
The operational unreliability of the AFW system calculated by arithmetically averaging the results of 72 plant-spacific models is 3.4 x 105 Individual results vary over two orders of magnitude, from 15 x 104 to 6.2 = 10d, The variability in AFW system unreliability reflects the diversity found in AFW system e
designs, and to some extent variation in results among plants with similar designs.
AFW designs composed only of turbine-driven pumps were the least reliable, while AFW designs comprising three redundant trains of diverse design (e.g., two motor and one turbine drtven pumps) were more reliable. The benefit of additional trains of redundancy to AFW system reliability is offset by the effects of common cause failures.
In accordance with our peer review process prior to the finalization and distribution of this report, we want to provide you with the opportunity to review and comment on the draft report.
We would welcome your comments relating to the methods, data, and findings. To meet our planned publication schedule, we would appreciate receiving your comments within 45 days from receipt of this letter.
As you r.iay know, the Office for Analysis and Evaluation of Operational Data studies do not c\\
represent an official U.S. Nuclear Regulatory Commission position or the position of the f Q ')
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responsible NRC program office. Our reports are one input to an ongoing review and evah'ation process.
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C Mr. Andrew Drake 2-A copy of this draft report and letter are being placed in the Public Document Room at 2120 L Street NW, Washington, DC 20555.
If you have any questions related to this report, please feel free to contact Dr. Dale Rasmuson (301-415 7571) (e-mail: dmr@nrc. gov) of my staff.
Sincerely, original signed by Charles E. Rossi, Director Safety Programs Division Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Identicalletters sent to:
Mr. Ralph E. Beedle Mr. V.K. Chexal, Director Nuclear Energy Instituto Nuclear Safety Analysis Center 1776 l Street NW, Suite 400 Electric Power Research Institute Washington, DC 20006-3708 P.O. Box 10412 Palo Alto, CA 94303 Mr. William J. Hastie Mr. J.J. Kelly, Manager Institute of Nuclear Power Operatior.3 B&W Owners Group Services 700 Galleria Parkway Framatome Technologies, Inc.
Atlanta, GA 30339 5957 P.O. Box 10935 Lynci.ourg, VA 24506 0935 ABB Combustion Engineering Owners Group Mr. Dennis Townsend clo Gordon Bischoff, CEOG Project Manager G.E. Nuclear Energy OwnersGroup M.S. 9615-1932 G.E. Nuclear Energy 2000 Day Hill Road 175 Curtner Avenue M/C 187 Windsor, CT 06095 San Jose, CA 95125 Distribution:
RRAB RF DHickman TOMartin SPD RF JRosenthal JMitchell File Center TTMartin Public AThadani DOCUMENT NAME: H:\\DMR\\LOSP-OUT.WPD
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DATE 01/13/98* dy suays 01/13/98*
01/14/98*
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