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October 15, 1979

NOTE FOR: J. Angelo, DPM, NRRM. B. Aycock, DSS, NRR

,

R. Colmar, DOR, NRRG. E. Edison, PAS, RESD. C. Fischer, DSS, NRRS. H. Hanauer, AD/PS, DSS, NRRF. Odar, DSS, NRRF. H. Rowsome, AD/ PAS, RESM. Srinivasan, DSS, NRR

FROM: P. W. Baranowsky, PAS, RES

SUBJECT: DEVELOPMENT OF SHORT-TERM ACTION PLAN FOR PLANT SPECIFICSTATION BLACK 0UT ANALYSES

Using the guidelines and Task Action Plan outlines provided in a draft memorandumfrom F. Rowsome to S. Hanauer et al. and distributed at our last meeting onOctober 9,1979, I have developed a detailed statement of tasks with a scheduleand overall manpower requirements (attached) for the short-term station blackoutevaluation. Recognizing that the long-term program would require two or threeyears to complete, I am proposing that the short-term program be completedwithin approximately one-half year and implementation of short-term " fixes"should be accomplished as soon as possible, but within six months of the finalshort-term recomendations. A short-term program and implementation scheduleof greater length would, in my opinion, best be reconsidered as a long-term

The tasks, schedule, and manpower requirements were developed takingprogram.into consideration the experiences of the AFWS Study and the differences fromthis program, the currently perceived urgency of this work (somewhat less thanthe AFWS Study), and the regulatory inertia that exists.

The short-tem program will seek to develop and apply site and plant specificreliability models in the estimation of station blackout > probability for eachplant with an operating license. Th. will be coupled with the reliability ofcertain decay heat removal systems to obtain a rough probabilistic estimatetnat station blackout will result in core damage.

The longer term program is not developed here since it will obviously be impactedin scope and schedule by the results of the short-term program. Items thatwould be included in the longer term program are:

1. Development of more precise models for site / plant specific estimation ofstation blackout probability and characterization of failure modes,

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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 tothe resciution of that issue is scheduled for October 16,1979, at 11:00 am inthe PAS Director's office. ~

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4 V4 'i.c t' , 0 ,,pP. W. Baranowsky fProbabilistic Analysis StaffOffice of Nuclear Regulatory Research

Attachments: As Stated

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Attachment 1.

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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 subsequentevaluations will be developed and the qualitative and quanti +=tive basesstated.

3. Develop offsite and onsite (emergency) AC reliability models.

Plant specific AC reliability modeling will be developed. This willinclude a determination of the approach for site specific and/or regionaloffsite power reliability modeling and plant specific methodology forassessing the reliability of onsite, emergency AC power supplies.

4. Collect, evaluate, and prepare data.

Data for site / regional offsite power reliability and emergency onsite ACpower will be collected, evaluated and prepared for use in AC reliabilitymodels. Utilities will be contacted directly as necessary to establish anacceptable data package.

PWR Analysis Program

5. Perform PWR station blackout analyses.

Using the AC reliability models and data package, a plant specific evaluationof station blackout probability will be developed for all operating PWRs.The results will be coupled with the previously performed AFWS reliabilityanalyses to determine the sequence probability for station blackout withAFWS failure.

6. Reevalu8etentativerisk/reliabilitygoals. ~

In light of the insights learned from the PWR station blackout analyses,reevaluate the tentative risk / reliability goals developed earlier. Providea 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 stationblackout evaluations and identifying plants which will require short-termquick fixes or justification that the current station blackout sequencefailure probability is acceptable (i.e. , ability to cope is better or

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sequence is lower and satisfactory to NRC). The report (s) will identifyareas in which reliability improvements are recommended for specificplants 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 identifiedfor short-tem reliability improvements. Potential fixes and schedules-

will be discussed and an opportunity will be provided to justify that thestatus quo is acceptable while a more detailed study is undertaken.

9. Development of NRC position on recommended reliability improvements forPWRs.

Discussions with the plant owners and subsequent information provided, ifany, will be considered in the establishment of a final short-term recommendationfor reliability improvements.

10. Issue orders to implement NRC recommendations on PWRs.

A set of orders will be issued to affected owners outlining the NRC requirementsfor short-term fixes, schedule, and any operational limitations.

This step and subsequent implementation actions will be handled throughnormal D0R procedures. Further development is not provided here.

BWR Analysis Program

11. Develop BWR reliability models/ guidelines for decay heat removal systemsrequired during station blackout.

A set of models, approaches, and/or guidelines will be developed for thereliability analysis of BWR decay heat removal systems which would berequired during a station blackout.

12. Prepare and issue reliability analysis requirements to BWR owners.

The BWR decay heat removal systems reliability analysis package includingspecific instructions on the conduct and documentation of the analyseswill 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. Duringthe time period between fomal issuance and receipt of the requestedanalyses, several owner contacts or meetings may be required for clarificationor guidance.

14. Review BWR reliability analyses. 1734 268The BWR r2 liability analyses will be reviewed and, where needed, questionson the analysis will be provided to the owners for comment. Direct andinformal contact with quick turn around is expected; however, major unanswered

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questions may require an owners' meeting oinformation.r formal request for additional15.

Prepare NRC assessment of BWR reliabilit

heat removal systems requiredThe results of the NRC review of the BWRy analysis and transmit to utilities.reliability analyses for decay

and transmitted to the owners.during a station blackout will be prepIdentification of significant reliabilityshort commings will be provided with recommend dared

This task could be incorporated with thapproaches for improvements.e

station blackout sequence analysis to folloe task providing the rest ts of the16.Perform BWR station blackout analyses

w.,

Same as Task 5, but for BWRs.-

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17.Prepare results.of BWR analyses and tranSame as Task 7, but for BWRs. smit to utilities.

18.

Meeting with highest risk BWR plant owners.

Same as Tast 6, but for BWRs.19.

Development of NRC position on recommend dBWRs.e

reliability improvements forSame as Task 9, but for BWRs.

20.Issue orders to implement NRC recommendatiSame as Task 10, but for BWRs. ons on BWRs.

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SCHEDULE AND MANPOWER

StiORT-TERM PROGRAM FOR STATION BLACK 0UT

PWR --h h -- -h ' h- Implementation

Long-Term ProgramTask 3 @.@ @. [QSchedul e Implementation

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Manpower

|-- 2.5 \ 5.0 | 2.5 ~ ~~~~ -N~'

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Time EquivalentParticipant

Total Weeks 2--O 1 5 10 15 20 26 gFrom Start ,N o,

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