ML19291C033
| ML19291C033 | |
| Person / Time | |
|---|---|
| Issue date: | 10/15/1979 |
| From: | Baranowsky P NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Angelo J, Aycock M, Colmar R Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-44, REF-GTECI-EL, TASK-A-44, TASK-OR NUDOCS 8001110072 | |
| Download: ML19291C033 (6) | |
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October 15, 1979 NOTE FOR:
J. Angelo, DPM, NRR M. B. Aycock, DSS, NRR R. Colmar, DOR, NRR G. E. Edison, PAS, RES D. C. Fischer, DSS, NRR S. H. Hanauer, AD/PS, DSS, NRR F. Odar, DSS, NRR F. H. Rowsome, AD/ PAS, RES M. Srinivasan, DSS, NRR FROM:
P. W. Baranowsky, PAS, RES
SUBJECT:
DEVELOPMENT OF SHORT-TERM ACTION PLAN FOR PLANT SPECIFIC STATION BLACK 0UT ANALYSES Using the guidelines and Task Action Plan outlines provided in a draft memorandum from F. Rowsome to S. Hanauer et al. and distributed at our last meeting on October 9,1979, I have developed a detailed statement of tasks with a schedule and overall manpower requirements (attached) for the short-term station blackout evaluation.
Recognizing that the long-term program would require two or three years to complete, I am proposing that the short-term program be completed within approximately one-half year and implementation of short-term " fixes" should be accomplished as soon as possible, but within six months of the final short-term recomendations. A short-term program and implementation schedule of greater length would, in my opinion, best be reconsidered as a long-term The tasks, schedule, and manpower requirements were developed taking program.
into consideration the experiences of the AFWS Study and the differences from this program, the currently perceived urgency of this work (somewhat less than the AFWS Study), and the regulatory inertia that exists.
The short-tem program will seek to develop and apply site and plant specific reliability models in the estimation of station blackout > probability for each plant with an operating license. Th. will be coupled with the reliability of certain decay heat removal systems to obtain a rough probabilistic estimate tnat station blackout will result in core damage.
The longer term program is not developed here since it will obviously be impacted in scope and schedule by the results of the short-term program.
Items that would be included in the longer term program are:
1.
Development of more precise models for site / plant specific estimation of station blackout probability and characterization of failure modes, 1734 265 9 g 111o o 7 2.
2.
More accurate estimation of critical times, Maximum delay for initiation of non-AC-dependent shutdown coding, a.
b.
Point of no return for restoration of AC without core damage and other system reliability requirements, 3.
Accident recovery, prevention, and mitigation, 4.
Development of licensing criteria.
Our next meeting to discuss the issue of station blackout and this approach to the resciution of that issue is scheduled for October 16,1979, at 11:00 am in the PAS Director's office.
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Probabilistic Analysis Staff Office of Nuclear Regulatory Research Attachments: As Stated 1734 266 SHORT-TERM PLANT SPECIFIC STATION BLACK 0UT ANALYSES 1.
Set up program - structure and mechanics.
A detailed description of the program will be developed including schedule, manpower commitments, coordination requirements, description of implementation, and general responsibilities.
2.
Develop tentative risk / reliability goals.
A set of risk / reliability goals to be.used as a measure in subsequent evaluations will be developed and the qualitative and quanti +=tive bases stated.
3.
Develop offsite and onsite (emergency) AC reliability models.
Plant specific AC reliability modeling will be developed.
This will include a determination of the approach for site specific and/or regional offsite power reliability modeling and plant specific methodology for assessing the reliability of onsite, emergency AC power supplies.
4.
Collect, evaluate, and prepare data.
Data for site / regional offsite power reliability and emergency onsite AC power will be collected, evaluated and prepared for use in AC reliability models.
Utilities will be contacted directly as necessary to establish an acceptable data package.
PWR Analysis Program 5.
Perform PWR station blackout analyses.
Using the AC reliability models and data package, a plant specific evaluation of station blackout probability will be developed for all operating PWRs.
The results will be coupled with the previously performed AFWS reliability analyses to determine the sequence probability for station blackout with AFWS failure.
6.
Reevalu8etentativerisk/reliabilitygoals.
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In light of the insights learned from the PWR station blackout analyses, reevaluate the tentative risk / reliability goals developed earlier.
Provide a basis for any changes.
7.
Prepare results of PWR analyses and transmit to utilities.
A report or reports will be prepared outlining the results of the station blackout evaluations and identifying plants which will require short-term quick fixes or justification that the current station blackout sequence failure probability is acceptable (i.e., ability to cope is better or 1734 267 e
sequence is lower and satisfactory to NRC).
The report (s) will identify areas in which reliability improvements are recommended for specific plants and a proposed implementation schedule.
8.
Meeting with highest risk PWR plant owners.
A meeting or set of meetings will be held with the owners of plants identified for short-tem reliability improvements.
Potential fixes and schedules will be discussed and an opportunity will be provided to justify that the status quo is acceptable while a more detailed study is undertaken.
9.
Development of NRC position on recommended reliability improvements for PWRs.
Discussions with the plant owners and subsequent information provided, if any, will be considered in the establishment of a final short-term recommendation for reliability improvements.
10.
Issue orders to implement NRC recommendations on PWRs.
A set of orders will be issued to affected owners outlining the NRC requirements for short-term fixes, schedule, and any operational limitations.
This step and subsequent implementation actions will be handled through normal D0R procedures.
Further development is not provided here.
BWR Analysis Program 11.
Develop BWR reliability models/ guidelines for decay heat removal systems required during station blackout.
A set of models, approaches, and/or guidelines will be developed for the reliability analysis of BWR decay heat removal systems which would be required during a station blackout.
12.
Prepare and issue reliability analysis requirements to BWR owners.
The BWR decay heat removal systems reliability analysis package including specific instructions on the conduct and documentation of the analyses will be sent to each owner. The required response time will be identified.
13.
Receive analyses from BWR owners.
The results of the analyses will be required by a specified date.
During the time period between fomal issuance and receipt of the requested analyses, several owner contacts or meetings may be required for clarification or guidance.
14.
Review BWR reliability analyses.
1734 268 The BWR r2 liability analyses will be reviewed and, where needed, questions on the analysis will be provided to the owners for comment.
Direct and informal contact with quick turn around is expected; however, major unanswered
questions may require an owners' meeting o information.
r formal request for additional 15.
Prepare NRC assessment of BWR reliabilit heat removal systems requiredThe results of the NRC reliability analyses for decay and transmitted to the owners.during a stati short commings will be provided with recommend d ared This task could be incorporated with thapproaches for improvements.
e station blackout sequence analysis to folloe task providing the 16.
Perform BWR station blackout analyses w.
Same as Task 5, but for BWRs.
17.
Prepare results.of BWR analyses and tran Same as Task 7, but for BWRs.
smit to utilities.
18.
Meeting with highest risk BWR plant own ers.
Same as Tast 6, but for BWRs.
19.
Development of NRC position on recommend d BWRs.
e reliability improvements for Same as Task 9, but for BWRs.
20.
Issue orders to implement NRC recommendati Same as Task 10, but for BWRs.
ons on BWRs.
1734 209
SCHEDULE AND MANPOWER StiORT-TERM PROGRAM FOR STATION BLACK 0UT PWR
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