ML19224C852
| ML19224C852 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/25/1979 |
| From: | Basdekas D NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | NRC COMMISSION (OCM) |
| References | |
| NUDOCS 7907090441 | |
| Download: ML19224C852 (2) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION E
WASHING TON, D. C. 20555
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f gv f May 25,1979 NOTE FOR: The Commissioners D. L. Basdekas, ARSRhYb,
FROM-Attached for your information is a comparative listing of safety concerns before, and actions a fter the TMI accident.
This is not a unique case, but it is illustrative of the kind of problems, which the Commission will have to address with dispatch and determination.
Please nottthat this is a generic problem applying to all nuclear power plants in this country. My understanding of the manner it is being addressed by the staff, leads me to believe that it leaves a great deal to be desired in assuring the safety of operating power plants.
I urge you to give this matter your focused attention, however difficult it may be to do so under your present. heavily taxed calendar.
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A COMPARATIVE LISTING OF SAFETY r0NCERN5 EEFORE AND ACTIONS AFTER THE TMI ACCIDENT SAFETY CONCERNS EXPRES5[D BY 0. L. BASDFKAS, REACICR SAFETY ENGINEER, RECOMMINDAll0NS BY THE NRC REGULATORY STAFF INCLUDING A C0mifMENT U. 5. NUCLEAR REGULATORY C0 m 155 ION ON NOVIH8fR 19, 1976 AND MADE BY EABC0CK AND WILC0X COMPANY, OESIGN[R OF lHR(( Mite ISLAND (IM C DECEMBER 20, 1976 SAFETY IS5UE NO. 22, NUREG-015)
UNIT 2 NUCLEAR POWER PLANI SUBSEQU[NT 10 THE ACCIDENT AT IMI On April 26, 1979, almost a month after the TMI accident The Babcock and SAFETY IMPLICATIONS OF CONTROL SYSTEM FAllORES AND Wilcox Company, designer of the IMI Nuclear Power Plant, made the following Pl%T DWAMC5 commitment to NRC by letter f rom J. H. MacMillan, Vice-President Nuclear Division to H. R. Denton, Director, Office of Nuclear Reactor Regulation, U.S.N.R.C.
"The ef fects of control system f ailures or, sometimes, non-f aulted operation on safety are not being systematically reviewed. I believe that their effects
" Subj ec t: Integrated Control System on safety and plant availability should receive the proper attention. The first step would be to have the applicants perform a Failure Mode and Ef fects This letter documents the commitment of Babcock and Wilson to Analysis (fMEA) for normal operation, and in conjunction with postulated undertake a reliability analysis of the Integrated Control accidents and other off-normal events.*
System (ICS) which will include a failure mode and effects analysis. This analysis will identify sources of transients, if "In evaluating plant safety, the ef fects of control system malfunctions should any, initiated by the ICS and develop recommended design be reviewed as initiating events for anticipated transients and also as failures improvements which may be necessary to reduce the f requency of that could occur concurrently or subsequent to postulated anticipated events these transients.
(initiated by a different malfunction) or postulated accidents."
In addition, means will be developed for decoupling of the one has to consider that design features to mitigate the consequences of auxiliary feedwater control of steam generator water level from such events are not established, and therefore, those provided for postulated the ICS. This modification will provide control of feedwater and analysed accidents may not be sufficient, thus, in essense, having an under emergency conditions independent of the ICS.
unprotected series of events."
The scope of the reliability analysis and schedule for both the On a related issue on reliability and risk assessment:
analysis and development of indepenoent feedwater control will be provided within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />."
i common mode failures and events that may result in such failures, along with human factors, are expected to contribute most significantly to the On May 16, 1979 the NRC Regulatory Staff issued report NUREG-0560 entitled (From Olscussion of Issue No. 88, Staf f Report on the Generic Assessment of Feertwater Transients in Pressurire unavailability of the shutdown system.. "
Water Reactors Designed by The Babcock and Wilcox Company."
The report recomends that:
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"All classes of operating plants should be reanalyzed using y d {@f j g
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failure mode and effects analysis to identify realistic plant s.
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interactions resulting from failures in non-safety systems, h
b t) U O J. U U 6 b w safety systems and operator actions during transients and accidents."
"The role of control systems in all plants, and their signifi-cance to safety, should be reevaluated by NRC and the vendors.
Un countering Basdekas' arguments in December 1976 the NRC Regulatory Staf f The evaluations should be performed by the industry with guide-maintained:
lines developed by the NRC. Consideration should be given to establishing criteria regarding the rate at which transients challenge the plant safety systems. Such transients should "Although analyses have not been performed for these postulated include (a) those initiated by control f ailure plus (b) those sequences of events, the staff believes that the consequences initiated outside the control system that are not successfully would be acceptable, and much less severe than those calculated altigated by the contrnl system."
for postulated accidents."
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