ML20008F392
| ML20008F392 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 03/06/1981 |
| From: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8103130223 | |
| Download: ML20008F392 (4) | |
Text
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Consumers o
Ruamall B. DeWitt 5
Mce President
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Nuclear Operatsons 93)/
oeneral of*1ces: 212 West Michigan Avenue, Jackson, MI 49201 e (517) 788-0550 March 6, 1981 L @/
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Mr Harold R Denton, Director Office of Nuclear Reactor Regulation 8;
E US Nuclear Regulatory Commission b
8 Washington, DC 20555 DOCKET 50-155 - LICENSE DPR fP BIG ROCK POINT - PROBABILISTIC RISK ASSESSMENT Consumers Power Company representatives have met previously on several occa-sions with members of your staff to discuss our plans for enhancing the over-al2 safety of our Big Rock Point Plant. We believe that the most effective way to identify those Plant characteristics which represent the greatest potential risk to the health and safety of the public is by means of a Probabilistic Risk Assessment (FRA). This approach is censistent with the recommendations of NUREG-0585, "TMI Lessons Learned Task Force Final Report" (dated October 1979), to perform a systematic reliability evaluation of Plant systems and to define a quantitative risk goal as a threshold for backfitting of new requirements to existing plants. Your October 14, 1980 letter acknowledges the PRA program (outlined by our February 22, 1980 letter) as "a valuable tool for providing insight into the identification of significant contributors to risk." Therefore, a comprehensive PRA for Big Rock Point utilining probabilistic analysis methods similar to those employed in WASH-1400, Rasmussen Report (1975), has been undertaken with completion anticipated in the very near. future.
PRA is considered the most appropriate way to assess the overall safety of Big Rock Point. Some of the major reasons for this position are:
1.
Big Rock Point is one of the oldest boiling water reactor plants and is unique with respect to Plant design, size (240 MWt) and location.
Specifically, the relatively simple Plant design and small size make an alternate approach to that of generic regulation (ie, TMI Action Plan, NUREGs and generic letters) necessary for adequately addressing new safety concerns as they arise. Typically, generic documents / regulation address a standard plant which has significantly different systecs and operating parameters from Big Rock Point.
oc0381-0068a-48 3180 QD
Mr Harold R Denton 2
Sig Rock Point March 6, 1981 2.
The comprehensive and integrated approach used in the FRA allcws the determination of the best solution to potential risk contributing proble=s from both risk reduction and benefit / cost perspectives. The icng, safe operating history of Big Rock Point lends itself to this approach because of the extensive Plant specific history which allows reliable deter =ina-tion of potential contributors to risk.
3.
The PRA approach involves the determination of contributors to risk, thereby resulting in a preventative approach to risk minimization rather than a mitigative one. Consu=ers Power Company considers the preventative approach to safety to be the best for Sig Rock Point.
The relatively small revenues generated by Big Rock Point necessitate that the integrated approach to risk reduction provided by the PRA be used to develop the highest benefit / cost solutions to potential proble=s. Significant sums of money cannot be spent on solutions which provide little or no increase in safety. The integrated approach to systems analysis utilized by the PRA results in the definition of better solutions to problems than may be visible when dealing with the sa=e problems on a basis generic to all boiling water reactors or an individual' basis for discrete Plant systems.
- Strong incentives exist for the continued operation of Big Rock Point. A=eng these incentives that make continued operation beneficial to both Consumers Power Company and the commercial nuclear power program in the United States are:
1.
Big Rock Point's ability to obtain mid-and late-life operating experience in.the near term, including identification of possible unforeseen problems at a lower public risk than if such experience were to be gained solely at larger plants in the distant future.
2.
Big Rock Point's participation in an active Depart =ent of Energy light water reactor fuel research program. The new fuels being evaluated have the potential for improving fuel performance and reducing the risk of fuel failure at all nuclear power plants. This~ program =ay not be economical at larger plants.
3.
Big Rock Point's ability to provide the power equivalent of 3,000 barrels of oil-per day. Consu=ers Power Co=pany's system design is such that replacement power for Big Rock Point has to be generated aimost entirely from oil-fired plants.
It is our intentica to use the PRA as a safety assessment tool for all current and future assessments of risk associated with identified and postulated problems:(ie, generic safety issues, plant specific equipment and operating problems, etc). The major objective of this ' type of approach is to provide a systematic and integrated assessment of the risk to the public for the entire -
Plant, thereby assuring that modifications to the Plant design or operation
-defined for. an individual problem are of sufficient value to be warranted and do not adversely affect'other Plant systems. Preliminary PRA results show the oc0381-0068a-43
Mr Harold R Deaton 3
Big Rock Point March 6, 1981 i
frequency of core damage events to be 9.8 x 10 ' per year for Big Rock Point as it currently exists. A carefully selected group of Plant design modifica-tions have been identified which, if implemented, would lower the Big Rock Point core damage frequency by a factor of 15 to 20.
Upon completion of these modifications, the risk to the public will be substantially reduced and the significant contributors to risk eliminated. Any remaining contributors to risk have a small individual impact on risk and their elimination would be unwarranted from either a safety or cost viewpoint. A procedure is being developed to update the PRA for changes in Plant design, operation and equip-ment reliability history so that evaluation of generic and Plant specific safety issues may be made with a current PRA model of the Plant.
l The acceptance of the PRA by the NRC, as a major licensing and safety assessment tool, is necessary for the continued operation of Big Rock Point.
We have scheduled a presentation with meubers of your staff for March 17 and 18, 1981. On the first day of the presentation, it is intended to provide an Executive Summary of the results of the PRA, the methodology used and our plans for its future use.
An agenda is provided as Attachment 1 to this letter for the first day's activities. On the second day, detailed results and answers to specific questions that your staff may have will be presented.
A rough agenda will be provided on March 17, 1981 for the second day's activities, but it is our intention to have a relatively free format so that your staff may pursue their own areas of concern and interest.
Your attendance at the initial portion of the March 17, 981 meeting (Executive Summary) would be welcomed.
R B DeWitt (Signed) i i
R B DeWitt, Vice President Nuclear Operations CC Director, Region III, USNRC NRC Resident Inspector Big Rock Point l
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ATTACIDIENT 1 MEETING AGENTA I.
EXECLTIVE
SUMMARY
A.
Motivation for Study B.
Study Objectives C.
Results II. METHODOLOGY A.. Understanding the Plant B.
Event Tree and Fault Tree Construction C.
Data and Quantification D.
Consequence Analysis III. RISK OLTLIERS A.
Dominant Core Damage Sequences B.
Plant Characteristics Contributing Most to Dcminant Sequence C.
Methods of Dealing With Risk Outliers (Proposed Plant Modifications)
IV.
PROPOSED PLAN (SHORT TERM)
A.
Application to NUREG-0737 Items B.
~Special Issues V.
FL'IURE STRATEGY (IDNG TERM)
A.- Continuing Risk Management Program B.
Integrated Program To Address Key Licensing Issues (SEP, IREP, Degrade Core Rulemaking)~
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