ML19338C593
| ML19338C593 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 07/25/1980 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Cavanaugh W ARKANSAS POWER & LIGHT CO. |
| References | |
| NUDOCS 8008180227 | |
| Download: ML19338C593 (8) | |
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NUCLE /sH RECUL A i ORY CCT. J,1CION f
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Int:rin Reliability Evaluation Progrca (IREP) - Phase II
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uo m ore a for manage xnt overs igh t onJ r ulir.clion.
Enclosed are (1) Li;e curr :nt de ti t af L',e I,MP n < ' ros
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- 1 e (2) the draf t IREP Evcnt Trce Cuide, and (3) a draft gJi'e for
- i L. ting o nent failure rates.
1.e opact Lhot those it ' s will be c4 incJ, oc!..li tcJ in the cauing uce!:s.
It is cur intention to inse LE :ir ravision on the co.: :ents of the Prebabilistic Analysis Staff and its [ni.P c m! cc.clo r, O nd ia ra tional ISa ra ta ries.
','e da no t c x p e c t sub,Luntial al terations to the Lechnical w,0cch.
"am.er,
- 2 nd "t tia are i>Unj sp:cial care to select the inici,
- iate nilestones for Jc M a Lion m i revit s!.
1.'s ! a th ! 3 pe t o mare 'iigh a.1 cansis tcnt li ty, i nt at the s ae Li :e avoid the diss ipa tion of rJourucs on pr iture s!;tus reparts and their evaluation.
The cacloseJ Piacedure ar.i % 'ule ruide represents Qat ca consider t' e strictest appraach to la th procedure and schedule.
Fe are presently can'idering substantial relaxa tion of ba th aspects.
'Ne P ee taken to calling this proce:iural guide a cookback.
..e dislike the tera "cooktvok" since it implies a U211 established recipe for
<o. 'e th ing.
','e 6 n)t have a well est,bl ishmi i ccipe fo r pariu r..ing an interin reliabili ty evalua tion of a plant but cre trying to d.,velop
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fir. Willian Cavanaugh, III !'any of the licensee's concerns with IREP Phase II have been enumerated in a letter from Arthur Lundvall of Baltinore ras and Electric Company (CG^E) to f:RC dated June 25, 1980.
This letter, too, is enclosed for ease of reference (Enclosure 4).
Ue think f:r. Lundvall's concerns warrant a detailed reply, not just to BG&E but the other osiners of IREP II plants as vall.
The concerns are generic.
TVA has sent us a letter expressing similar concerns.
Arkansas Power and Light has conditionally agreed to proceed with the IREP program but has also expressed these Colicerns.
1.
Schedule Ue are mre concerned with promptly initiating the IREP Phase II studies than we are with rushing to judgment on the results.
Just as we are proceeding with deliberation on the completian of the Phase I study of Crystal River, we are fully prepared to cudify the whedule on the completion of a Phase II study if that is necessary perfona an adequate job.
i.
Our sense of urgency on the inception of the Phase II studies is based upon a perception in both RES and t'RR at NRC that it is desirable to survey all operating reactors in IREP-like studies as soon as practically possible.
This vark is covered in the Task Action Plan (NUREG-0660) as Tasks II.C.1 and II.C.2.
The Phase II IREP studies will serve, among other objectives, as a proving ground for a study scope and task description that can be followed on all plants with the resources the NRC and the industry night realistically be able to provide within the next few years.
The objective is to distill the essence of risk assessment to a level that ',ould penait a plant to be studied in less than a year by a team composed of two experienced system reliability analysts, one engineer thoroughly versed in the design and operation of the plant; and three reactor systems engineers of the background comaonly found in utilities, vendors, or architect-engineer staffs.
These teams are to generate a standardized and meaningful product, albeit one that is not so complete as one entailing, say, thirty man years effort per plant.
f;RC plans to prepare the procedural guide (perhaps in collaboration with the industry) drawing upon the Phase II experience and I;RC will request, sonetime in 1981, that these studier be started on operating plants.
Roger l'attson has suggested a 1) rum for industry input on the procedural guide, to v;hich I will tura later.
It is with this background that we feel a sense o'.
uroency to get on with the i ception of the Phase II studies.
It is also responsible for the impression ue gave that the " cookbook" is still developing; we intend to be tarking or the Phase III procedural guide throughout Phase II, drawing upon the Phase II experience.
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fir. William Cavanaugh, III 2.
Tiethodology_
Ue feel that the state-of-the-art in probabilistic risk assessment is quite well-developed through many applications, refinements, and peer review.
There are many shortcomings in the completeness and precision of available techniques but the time is ripe to divert some of our research resources from the advancement of the frontiers of risk assessment to the broad scale application of the well-developed portions of the discipline.
Our principal problea in this context is to distill the essence of the techniques that are well known to the community of experienced practitioners into a fom that can be usefully implemented by many small teams of less specialized analysts throughout the industry in a comparatively short period of time.
We are targeting a plant ;ecific catalog of core melt accidents that is abstract enough to be 'airly plete yet specific enough to be useful in risk assessment, ope
.o r training, emergency planning, and the like. The statc c-the-art in event tree analysis can suppoi t this.
In addition, we are aiming for the perfomance of system reliability analysis and common-cause failure analysis - including operator error - of sufficient depth to give fairly good odds that the risk-dominant accident sequences will be identified.
In particular, we want to screen the subject plants for susceptibility to those accidents in which common factors couple the initiating event with the degradation of the reliability of the systems expected to mitigate the event, N
e.g., scenarios like T!1I or the fillI-bus faults at Rancho Seco and Crystal River.
The task of preparing the instructions for such studies requires input from experts in risk assessment and the experience of the Phase II studies.
We welcome industry input to the Phase III instructions developed in parallel with the Phase II effort.
However, it would unnecessarily delay the procram to schedule une industry input to Phase II and thereby substantially delay F.e conduct of this phase.
3.
Timing vs. Plant Alterations It is not a problem to incorporate in IREP studies design or procedural alterations that are well-planned but not yet implemented.
Fo r example, the Crystal River Unit 3 study credited alterations to the Emergency Feedwater System that were just evolving from conceptual to detailed design as the study was in progress.
For those cases in which a conceptualized change is not yet well enough elaborated for codeling in a system reliability analysis, it is feasible to perfom sensitivity studies which could give useful input to detailed design or procedural implementation.
Therefore, vie see as many or more advantages as disadvantages in performing IREP studies while the Till modifications are 11 the pipeline.
Mr. William Cavanaugh, III 4.
Licensee Participation As you can see, the IREP Procedure and Schedule Guide provides for a number of points at whic'1 preliminary results and working papers are submitted to the plant owner as well as the fiRC Research and Sandia IREP program management for review and comment.
There will be ample opportunity for the owners' engineering and operations personnel to keep posted on the developing study. 1le welceme your suggestions for improvements in the structure of this oversight.
He intend to provide periodic briefings of NRC and licensee manage-ment on the progress of the IREP reviews. At these times, if you have any basic problems with the conduct of the studies, you will have ample opportunity to voice your concerns.
We muld welcome the membership on the IREP study teams of one to three engineers drawn from and supported by yourselves (the owner) or your consultants. We think it wuld be more valuable to you as well as to the team effort if your participants on the IREP team are drawn from your engineering or operations staffs. An individual thoroughly familiar with the design and operation of the plant would be the most useful to the study team.
One who knows to whom to mute technical design or operations questions muld enhance the speed and accuracy of the IREP effort.
Such an individual would be particularly well suited to maximize the benefit of the experience for yourselves as well.
That person muld be equipped to translate s
the engineering insights that will be implicit in the study into useful guidance for your conduct of operations, maintenance, personnel training and the evaluation of retrofit options.
The experience would enhance the participant's usefulness in economic risk management, availability engineering, and in dealing with subsequent regulatory issues as well.
That person need not have prior experience with risk assessment or system reliability analysis - an alert individual can learn much of that through the IREP experience.
Such team members detailed to IREP from your staff will be free to keep you posted of the team's activities as you see fit even outside the framework of scheduled IREP reporting.
You may also want to employ the services of a competent risk assessment engineer to help in your review of the preliminary reports and the subsequent draft repo rt.
While we wuld be happy to accept such a consultant as a detailee to the IREf team, we muld prefer members of your own s ta f f.
NRC is paying for these IREP studies. He and our contractors will provide wrking space for participants sent by the owner.
- Salary, travel and subsistence cost. for the owner's representatives are the responsibility of the plant owner.
From time to time in the IREP study there may arise technical questions about plant response which may not be answerable from existing records.
These questions will be directed to the owner for response. Any costs of special
l fir. William Cavanaugh, III analysis by the owner or support by contractors to the owner are the responsibility of the plant owner. He do not expect to encounter a large number of such questions or any which require extensive J
special analysis.
Our experience in the Crystal River IREP supports this expectation.
5.
Regulatory Ratcheting The controversy surrounding the Reactor Safety Study,-the many reviews and criticisms of it, and the culmination of that contro-versy in the i.ewis Committee Report is fresh in our minds. He are very conscious that careless use of probabilistic risk analysis can lead to incorrect understanding and action. At the same time we and many others are convinced that probabilistic risk ar.alysis is a tool which can make substantial contributions to nuclear safety.
Certainly, if we had all heeded the message of the Reactor Safety Study, we would have focused our attentions on transients, small breaks, and operator error years ago.
Perhaps the TMI accident would have been prevented if we had.
As you know, many groups have undertaken probabilistic risk analyses now and we must address what to do with the results.
It is not enough to say that the results of such an analysis should be carefully l
reviewed and considered.
Such analyses, if carefully done, can reveal the Achilles heel of the plant and give a fair measure of s
how vulnerable the plant is to serious accidents.
We need a consistent way to decide whether to backfit the plant to reduce either the likelihood or the consequences of the accidents which dominate the risk.
Duners and the NRC naed to look at the results of these analyses, considering their cuality and their uncertainties, and decide what changes, if ar.,, are warranted.
In virtually every case I would expect the owner of the plant to factor the results of these analyses into the plant's procedure reviews and operator training.
In many cases I would expect the analyses tri identify areas where minor changes in testing, maintenance, or Mrdware would substantially reduce risk; and in other cases, ana'yses will
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point to design features of the plant which are not easy to change.
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The owner's voice should be the first heard on what changes are warranted, but I realize that many owners are concerned that NRC will press ahead with ratcheting decisions before the owner is heard.
The best way to avoid this is for the owner to follow the analysis closely, evaluate the significance of findings as they develop, and take the lead in identifying what actions are appropriate.
A larger forum has been proposed for joint industry and NRC consideration of probabilistic risk analysis methods and their use in regulation.
The NRC and the Institute of Electrical and Electronic Engineers l
(IEEE) held a joint technology transfer conference here in Washington in January of this year.
The first proposal for followup action i
Mr. William Cavanaugh, III made by the steering committee of that conference was to encourage industry and NRC consideration of probabilistic rid analysis methods and uses in a structured technical forum.
This idea led to a meeting at the IEEE on May 15, 1980 where Roger Mattson of the NRC proposed NRC/ industry collaboration on the procedures and policies to govern the extension of IREP to all the operating nuclear plants. A copy of the minutes of that meeting is enclosed as Enclosure 5.
He suggested that this initiative be hosted by the IEEE as a neutral technical (and public) forum with unique connections to related areas of expertise.
He suggested that two committees be fo med. One of these wuld be a steering committee composed of managers to deal with issues such as objectives, schedules and resource constraints, and consideration of the fom and quality of IREP results for ultimate use in regulation.
The second w uld be a working group of experts in risk assessment to wrk up the scope, procedures, and assumptions for the accomplishment of IREP Phase III or the " National Reliability Evaluation Program," NREP, as Roger calls it.
In addition to the host role, the IEEE muld obtain periodic input to the two committees from its resources in j
non-nuclear industries that have extensive experience in system reliability analysis and reliability assurance.
There was another meeting on June 11, 1980.
Nuclear industry representatives at the meeting were Walt Fee of Northeast Utilities, Bob Szalay of the Atomic Industrial Forum, and Ed O'Donnell of s
Ebasco Services who is chairman of the AIF Ad' Hoc Committee on Probabilistic Safety Analysis.
The AIF Ad Hoc Committee has since met and we expect to meet with them again here in Washington on August 5.
I believe that I have addressed the three recommendations with which Mr.
Lundvall's letter closes but, to summarize:
a.
, Licensee Input on Methodology and Assumptions.
There will be ample opportunity for licensee input on the way the plant is modeled:
system success criteria, points of no return, accident phenomenology, and the rodeling of system behavior.
The teams will be under instructions to use the most realistic (but justified) data on system behavior and plant response that is readily available.
They are also to weed out any identifiable conservatisms in the final analyses of those accident sequences that rise to prominence in the preliminary screening.
There will also be ample opportunity for licensee review of interim reports, the draft report, and the final i
repo rt.
b.
Schedule. As noted above, we wish to proceed to the draft report stage to garner the experience with the use of the procedure guide which is needed to prepare for Phase III. We will not rush an
- r.1.'illian Cavanaugh, III inconplete.ich into print in a final report.
The end date nay slip l
i as necessary to achieve a cuality product.
At the same tine I an cuare, as I am sure you are, of the danger of 't:aving a poor quality j
draft rcport in existence with a correcting final report too distant.
I sculd lil:e to beain work by gathering the tea.ns in late Aucust. Based on your coments v.o now propose to har.dle I:filstone 1 and Calvert Cliffs in !*ashington, Arkansas 1 in Albucuerouc,1:ew I'cxico, and Erouns Ferry in Idaho Falls, Idaho.
I hope this piycs 30u the basis for enthusiastic participation in the IREP-II work.
I propose that we neet eith the four participating licensees on the afternoon of Aucust 4 f cre in Cethesda if Picase call you feel that such a rceting sould be of nutual benefit.
F.otert li. Ferncro, Director of the Probabilistic Inalysis Staff, Office of I:uclear Regulatory Research, on (301) 4?2.052P rith your vicus.
Sincerely.
Original signed by l
Darrell G. Eisenhut i
Darrcil G. Eisenhut, Director i
l Division of Licensing Office of fluc1 car Reactor Rerulatior l
Enclosurcs: As Stated cc c/ encl: See Attached List bec w/ encl: Docket File <
G NRC Public Document Room G. Vissing, NRR bec w/o encl:
R. Mattson M. Ernst S. Israel F. Rowsome J. Murphy R. Bernero l
Arkansas Power & Light Company cc:
Mr. David C. Trimble Mr.RobertSzalay,{.icensingand Manager, Licensing Safety Project Manager Arkansas Power & Light Company Atomic Industrial Forum P. O. Box 551 7101 Wisconsin Avenue Little Rock, Arkansas 72203 Washington, DC 20014 Mr. James P. O'Hanlon General Manager Mr. E. P. O'Donnell Arkansas Nuclear One Ebasco Services, Inc.
P. O. Box 608 89th Floor Russellville, Arkansas 72801 2 World Trade Center New York, NY 10048 Mr. William Johnson U. S. Nuclear Regulatory Coninission P. O. Box 2090 Dr. Edwin Zebroski Russellville, Arkansas 72801 Nuclear Safety Analysis Center 3412 Hillview Avenue Mr. Robert B. Borsum P. O. Box 10412 Babcock & Wilcox Palo Alto, CA 94303 Nuclear Power Generation Division Suite 420, 7735 Old Georgetown Road Bethesda, Maryland 20014 Mr. Nick Reynolds DeBevoise & Liberman 1200 17th Street, NW Washington, D.C.
20036 Arkansas Polytechnic College Russellville, Arkansas 72801 Director, Bureau of Environmental Health Services 1
4815 West Markham Street I
Little Rock, Arkansas 72201 fir. Paul F. Levy, Director Arkansas Department of Energy 3000 Kavanaugh Little Rock, Arkansas 72205 I
l Mr. William T. Craddock, Mgr.
I Availability Engineering First National Bank Building P. O. Box 551, Seventh Floor l
l Little Rock, Arkansas 72203
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