ML19261C948
| ML19261C948 | |
| Person / Time | |
|---|---|
| Issue date: | 02/08/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Boyd R, Mattson R, Stello V Office of Nuclear Reactor Regulation, NRC OFFICE OF STANDARDS DEVELOPMENT |
| References | |
| TASK-A-17, TASK-OR NUDOCS 7904190356 | |
| Download: ML19261C948 (25) | |
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UNITED STATES 4
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FEB 6 1379 sp A Generic Task No. A-17 MEMORANDUM FOR:
Roger S. Boyd, Director, Division of Project fianagement, NRR Victor Stello, Jr., Director, Division of Operating Reactors, NRR Roger J. Mattson, Director, Division of Systems Safety, NRR Richard C. DeYoung, Director, Division of Site Safety and Environmental Analysis, NRR
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~ " t c Guy A. Arlotto, Director, Division of Engineering Standards, OSD Anthony R. Buhl, Director, Probabilistic Analysis Staff, RES John C. LeDoux, Chief, Career Management Branch, IE FROM:
Denwood F. Ross, Jr., Deputy Director, Division of Project Management, NRR
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SUBJECT:
PROPOSED REVISION 2 TO TASK ACTI0fl PLAN FOR TASPs A-17, SYSTEMS INTERACTION IN NUCLEAR PONER PLANTS Enclosed is a draft copy of Proposed Revision 2 to the Task Action Plan for Task A-17, Systems Interaction in Nuclear Power Plants.
Your concurrence
.vith this revised plan is requested on or before February 14, 1979.
This plan was provisionally revised a year ago in February 1978 and had received the concurrence of Division Directors, NRR, at that time.
The revised plan was never fully acted upon or formally approved by the Technical Activities Steering Committee.
The enclosed draft on which you are asked to give concurrence has changed only slightly from the provi-sionally revised plan of one year ago.
The significant changes that have been made are:
(1) the completion date for Phase I has been extended from May 1979 to. september 1979, (2) the completion date for Phase II has been extended to September 1980, (3) review and critique by all cognizant branches has been simplified to leave this action as a matter of discretion by the individual branch chiefs, and (4) the draft plan now reflects the contributing effort from the Probabilistic Analysis Staff (RES) and the Career Development Branch (IE).
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D0R is specifically requested to update the current status of the contract effort at ORflL on control and protection systems interaction.
We under-stand that the work at ORflL is now on a " hold" basis pending the outcome of the Phase I task at Sandia Laboratories.
Please contact J. Angelo (27391) for any clarification or qualifying coments that you may care to make on this draft plan.
If your comments crn be incorporated in the plan, we will d so without resubmitting for your approval.
If there are conflictine s i ments, then we will resolve these and resubmit for your approval In order to expedite this review and your concurrence, a copy of the enclosed draft revision of the plan has been sent to the Deputy Directors, Assistant Directors, and Branch Chiefs of the branches with representatives on the fiRR Working Groups, and to members of the f1RR Working Groups.
W4Y Denwood F. Ross, Jr., Deputy Director Division of Project fianagement Office of fluclear Reactor Regulation
Enclosure:
Draft Proposed Revision 2 to Task Action Plan for Task A-17
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1 Task A-17 SYSTEMS INTERACTI0t45 Iti tiUCLEAR POWER PLAi1TS Lead f4RR Organization:
Division of Project Management Lead Supervisor:
D. F. Ross, Jr., Deputy Director, DPM Task Manager:
John Angelo, LWR-1/0PM Applicability:
Light Water Reactors Projected Completion Date:
September 1980
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a 1.
DESCRIPTION OF PROBLEM The design of a nuclear power plant is accomplished by groups of engineers and scientists organized into engineering disciplines such as civil, electrical, mechanical, structural, chemical, hydraulic, and nuclear, and into scientific disciplines such as geology, seismol-ogy, and meteorology.
The reviews performed by the designers incluae interdisciplinary reviews to assure the functicnal compatibility of the plant structures, systems, and components.
Safety reviews and accident analyses provide further assurance that system functional requirements will be met.
These reviews include failure mode analyses to assure that the single failure criterion is met.
The NRC review and evaluation of safety systems is accomplished in accordance with the Standard review Plan (SRP) which assigns primary and secondary review responsibilities to organizational units arranged by plant systems such as containment systems, reactor systems, etc.,
or by disciplines such as mechanical engineering, materials engineer-ing, and structural engineering.
Each element of the SRP is assigned to an organizational unit for primary responsibility and, where appropriate, to other units for secondary responsibilities.
L Thus, the design and analyses by the plant designers, and the subse-quent review and evaluation by the NRC staff, take into consideration A-17/1
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?i'd$ I the interdisciplinary areas of concern and accLwit for systems inter-action to a large extent.
Furthermore, many of our regulatory criteria are aimed at controlling the risks from systems interactions.
Examples include the single failure criterion and separation criteria.
Nevertheless, there is some question regarding the interaction of various plant systems, both as to the supporting roles such systems play and as to the effect one system can have on other systems, particularly with regard to whether actions or consequences could adversely affect the presumed redundancy and independence of safety systems.
The problem to be resolved by this task is to identify where the present design, analysis and review procedures may not acceptably account for potentially adverse systems interaction and to recommend the regulatory action that should be taken to rectify deficiencies in the procedures.
2.
PLAN FOR PROBLEM RESOLUTION The plan for resolution of this task is to develop a method for conducting a disciplined and systematic review of nuclear power plant systems, for both process function couplings of systems and space couplings, to identify the potential sources and types of systems A-17/2
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A matrix of systems ar.d interactions will be synthesized generically for a nuclear power plant and verified for a selected facility.
This matrix will be displayed as a plant logic and
/ stem models, for example, somewhat analogous to techniques that have already been developed for similar kinds of studies and analyses.
The Star.dard Review Plan will then be measured against this synthesized matrix to determine the completeness of the review procedure.
From this compari-son, any necessary revisions to the review procedures, including necessary revisions to Standard Review Plans, Regulatory Guides, etc., will be developed and recommended for implementation.
The plan will also include the development of criteria and procedures to assure that applicants incorporate appropriate systems interaction considerations into their design and review process.
The plan is to be accomplished in two phases.
Phase I will include the development of a systematic review process for plant systems and interactions and the verification of the Standard Review Plan against the results of the systematic review.
This phase is expected to be completed in September 1979.
Throughout this phase any results that indicate a need for immediate regulatory action will be identified and appropri'le reccmmendations made to management.
A final report summarizing the results of Phase I will be issued at the completion A-17/3
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of the, phase.
Phase II will be accomplished within approximately 12 months after the completion of Phase I.
This phase will include the preparation of follow-on actions that are necessary to implement the results of this task.
All of these follow-on actions will have been identified during Phase I.
The follow-on actions include any necessary revisions to the Standard Review Plan, Regulatory Guides, or other regulatory actions.
Since it is not possible at this time to specify what the nature, extent or scope of these follow-on actions might be, the detailed scheduling of Phase II cannot be complete: until most of Phase I wJrk has been accomplished.
The pla will be accomplished by the coordinated efforts of three groups:
(1).a Systems Interaction Working Group composed of i.7divid-uals selected from organizational branch units within the Office of Nuclear Reactor Regulation (NRR) that are impacted the most by plant systems interactions and accident analyses working with a Task Manager, (2) a group within the Office of Standards Development (050) working with a Project Manager in the Engineering Methodology Standards
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Branch of 050, and (3) a group working fce B'andia Laboratories under
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ttW contract to OSD Further details of this arrangement and the work to g
be accomplished by each group are provided in Sections 3, 4 and 6 of this Task Action Plan..At4achment-1-thews-thrlines of adminientive and-technicaNntrol that-are proposed-for th'e execution of TriTs j
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T5e niajor elements of this Task are described in the following paragraphs:
i (a)
Sandia Laboratories will, through.he accomplishment of the work described in Section 5 of this Task Action Plan, develop a systematic review process for systems interaction 3.
Sandia Laboratories will verify and demonstrate the review process for an examplary facility and will assets the Standard Review Plan against the systematic review process.
All of this w~11 he accomplished during Phase I of the Task.
In Phase II Sandia Lab ratories will, as determined to be appropriate and necessary, transfer the techniques of the review methodology to NRC for further use by the NRC staff and will provide assistance in the follow on actions indicated by the results of Phase I of the Task.
Sandia Laboratories will report the progress of work at periodic intervals.
(b) The NRR Systems Interaction Working Group will review and evaluate the work performed by Sandia Laboratories and will provide assistance in specialized technical areas to supplement the technical capabilities of the group at Sandia Laboratories.
The NRR Systems Interaction Working Group will also provide the evaluation needed to form the technical basis for NRR management decisions regarding the acceptability of the task efforts by A-17/5
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Sandia Laboratories.
The NRR group, through the Task Manager, will transmit its findings to the Office of Standards Development (050).
(c) The Office of Standards Development will administer and manage the contract with Sandia Laboratories through its assigned Project Manager.
050 will also provide technic.i review, evalu-ation and direction of the work performed by Sandia Laboratories in conjunction with the technical overview by the NRR System Interaction Working Group.
To accomplish this Task and to establish a uniform basis for review by cognizant review branches, it will be necessary to develop criteria for bounding the extent of systems interaction.
The criteria must define the items that will be retained in the matri.x of systems and interactions; ot;m" wise, the matrix will become unmanageable and the reviaw will not proceed :a a uniform basis.
The criteria will serve as the basis to elimiret jstems interactions of little or no safety significance.
These criteria will be developed early in the execution of the task in order to give purposeful direction to the task and to its review.
One of the end products of this task will be additions, where necessary, to the Standard Review Plan to assure that our review procedures A-17/6
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adequately address considerations for systems interaction.
Another end product will be a recommendation that a Regulatory Guide or other appropriate documentation be issued to provide guidance on the criteria, procedures, and information required related to applicants' analyses and review of systems interaction.
During the accomplishment of this task, consideration will be given to the use of the end products for operating reactors.
The method of accomplishing this objective will be by review of the task by the individual assigned from ti,e Division of Operating Reactors (DOR) to the NRR Systems Interaction Wer<ing Group.
Since some of the elements of this systems interaction task are common to the elements that have been and will be used in the Systematic Evaluation Program (SEP) currently being conducted by DOR, the assignment has been made from the SEP Branch.
This individual will make his recommendations to Division of Operating Reactors management.
3.
BASIS FOR CONTINUED PLANT OPERATION AND LICENSING PENDING COMPLETION OF TASK As discussed in Section 1, this task addresses the development of a systematic process to review plant systems to determine their impact on other plant systems.
The purpose of the task is to improve the licensing process.
It is anticipated that this task will confira A-17/7
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that current licensing requirements and procedures acceptably control the potential for adverse systems interactions, even though some modifications for improvement in the review procedures and licensing requirements may be made.
Current licensing requirements are founded on the principle of defense-in-depth.
Adherence to this principle results in requirements such as physical separation and independence of redundant safety systems, and protection against events such as high energy line ruptures, missiles, high winds, flooding, seismic events, fires, operator errors, and sabotage.
These design provisions supplemented by the current review procedures of the Standard Review Plan (NUREG-75/087) which require interdisciplinary reviews and which account, to a large extent, for review of potential systems interactions, provide for an adequately safe situation with respect to such interactions.
The quality assurance program which is followed during the design, con-struction, and operational chases for each plant is expected to provide added assurance against the potential for adverse systems interactions.
Plant licensing can continue pending ultimate resolution of this task because current licensing requirements provide an acceptable level of assurance against potentially adverse systems interactions.
Previous licensing procedures that were followed for those plants new operating A-17/3
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Experience to date has demonstrated that operating plants have been designed to provide reasonable assurance that adverse syste e interactions will not occur.
Certain events such as fires and hi aergy line breaks outside containment have been identified as hazards to safety related equipment which also could couple adverse systems interactions.
Corrective measures have been or are being taken on each plant to assure an acceptable level of protection against these hazards.
These corrective measures will also reduce the.atential for adverse system interactions.
In summary, the staff considers that present plant design and review procedures which have been developed and refined from these procedures followed for plants now in operation, provide reasonable assurance that unacceptable adverse systems interactions will not occur.
The results.of this task are expected to confirm this view, although some modifications to improve review procedures and licensing requirements may be recommended.
Accordingly, we conclude that while this task is being performed, continued operation and plant licensing can proceed with reasonable assurance of protection to the health and safety of the public.
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NRR TECHNICAL ORGAtlIZATI0 tis ItiVOLVED The conduct of the task shall be the responsibility of NRR.
The strong OSD contribution will be recognized by having an 050 represent-ative assigned as Project Manager working with the assigned NRR Task Manager.
Technical interface between 050 and NRR shall be conducted by the Task Manager for NRR.
The Task Manager shall also retain the responsibility through the Technical Activities Steering Committee for meeting objectives and schedules established for the task.
The Task Manager, through the lead supervisor, shall also be responsible for defining and revising, as necessa.y, the objectives and scheduled as would be done for any other Category A Task.
The technical branches of NRR that are most affected by systems interactions have each appointed a principal person to act as a point of contact between the Task Manager and the branch and to be the primary technical representative of the branch.
For all other branches within NRR, the Task Manager will act through the Branch Chief.
The branches most affected by system interactions are:
Auxiliary Systems Branch Instrumentation & Control Systems Branch Power Systems Branch Containment Systems Branch effluent Treatment Systems Branch Accident Analysis Branch Reactor Systems Branch Systematic Evaluation Branch A-17/10
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- 7 The representatives of these ihree branches shall form the NRR Systems Interaction Working Group working with the Task Manager and, as the occasion demands, working directly with members of 05D or Sandia Laboratory.
This group will provide consultation or direct technical contribution on selected probleins in their areas of expertise.
An adequate amount of time should be allocated by the branches to enable these people to perform this activity.
For present planning purposes, it is estimated about 20% time input of one man rer branch for the more heavily impacted branches to about 10% time for lesser impacted branches.
Based on an estimated time of 16 calend'ar months to accomplish Phase I, and an estimated time of 12 months to accomplish Phase I;, the following allocations of manpower requirements for the principal branches which have assigned personnel for the NRR Systems Interaction Working Group should be made:
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Man-Months Phase I Phase 11 Total Auxiliary Systems Branch 2.4 1.8 4.2 Instrumentation & Control Systems Branch 2.4 1.8 4.2 Power Systems Branch 2.4 1.8 4.2 Containment Systems Branch 1.2 0.9 2.1 Effluent Treatment Systems Branch 1.2 0.9 2.1 Accident Analysis Branch 1.2 0.9 2.1 Reactor Systems Branch 2.4 1.8 4.2 Systematic Evaluation Branch 1.2 0.9 2.1 Total 14.4 10.8 25.2 In addition to these individuals, virtually all technical branches within 055, OSE, 00R, and OPM will be requested to review and critique the end products of the task and provide a nominal level of time for consultation in selected areas.
The requirements of specific branches will vary as a function of their involvement with systems.
5.
TECHNICAL ASSISTANCE This task will be accomplished by assistance from Sandia Laboratories working under a contract that will be acministered by the Office of Standards Development.
The contract will cover a two phase effort A-17/12
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w-expended over an estimated time of 24 months.
The first phase will includ Task I through Task 13 as described below.
The first pnase is estimated to be completed in 16 months at a cost of 3440,000.
The second phase is estimated to be accomplished in 12 months at a potential cost of about $200,000.
This estimate for Phase II represents an
" upper-bound" estimation.
Actual requirements will be dependent on the results of Phase I.
The specific tasks to be accomplished by Sandia Laboratories are described in Attachment 2.
Since one of the major tasks is to define the scope of the program in more definitive details, the tasks described in Attachment 2 should be treated as reflecting the initial thoughts of Sandia Laboratories.
At appropriate points during the execution of this ta4k, and as the results become available, the results of the ongoing technical assist-ance program with Oak Ridge National Laboratory (ORNL) now being conducted by 00R will be used in the task.
In order to accomplish this objective, cognizance of the ongoing technical assistance program will be developed and maintained by review of published information, attendance at meetings, and conferences with personnel who are active in the program in 00R and ORNL.
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1 The scope of the task at ORill is to (1) identify and evaluate the safety significance of possible interactions between control and protection systems, (2) provide recommendations for possible design modifications or operational requirements, (3) perform a detailed analysis, including a failure mode analysis, of auxiliary control systems specified by the NRC for the purpose of identifying any dependence between these systems and the reactor protection system, (4) assess the possibility of control system failures resulting in a challenge to tne reactor protecticn system, and (5) eva_luate the significance of possible adverse interactions between protection and control systems, and the capability of the reactor protection systems to mitigate the consequences resulting from these interactions or from control systems failures.
Manpower and funding estimates for this task at ORNL are 15 man-months of support effort during FY 1979 at a cost of $50,000, 6.
INTERACTIONS WITH OUTSIDE ORGANIZATIONS This task is closely related to one of the generic items identified by the ACRS and, accordingly, will be coordinated with the Committee as the task progresses.
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- a. BR1 1, Meetings are anticipated with N555 vendors, A/Es, and utilities to assess the extent to which these organizations conduct reviews and analyses for systems interaction, and to keep these organizations informed of our developments.
It is not intended to conduct a formal review process through these organizations, however.
It is intended to develop a free exchange of information so that the task can take advantage of existing methods of review.
Commonwealth Edison Company has completed a somewhat limited systems interaction study for the Zion Station.
The Commonwealth Edis~on Company study consisted of a detailed review of Licensee Event Reports of those events which have occurred that involve undesirable systems interactions.
Bcth physical and electrical interactions were covered in the event review.
7.
ASSISTANCE REQUIREMENTS FROM OTHER NRC 0FFICES The Office of Standards Development shall manage the contract effort and shall also provide technical input to the task effort to (a) supplement the contract effort, (b) direct and evaluate the contract effort, and (c) interface with the technical and management efforts
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It is estimated that this effort by 050 will total h X
man-months during Phase I of the task.
The Phase Il effort has been estimated as about man-months but will be dependent on the results of Phase I.
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9.u 3 Tha Of fice of Inspection and Enforcement will provide assistance to Sandia Laboratories in the area of plant operations.
It is estimated the this effort will be about two man-months.
Assistance wiil be requested from the Probabilistic Analysis Branch, Office of Nuclect Regulatory Research, to provide consultant assistance in the detailed development and execution of this task action plan.
It is estimated that this total assistance from RE5 will be about three man-months of effort.
It i.s anticipated that this group can provide valuable insights into the task because of its involvement with the Reactor Safety Study (WASH-1400).
Additionally, this group would be requested to review and critique the results of this task action plan.
8.
POTENTIAL PROBLEMS One of the problem areas is that systems interaction cuts across all disciplines and technical branch review areas and cuts across all groups and divisions.
Consequently, 4n-oeder to effectively perform 4
/Naar Zu a review for systems interaction, it i+'necessary to either define 4
more clearly and more extensively the primary and secondary review 747 responsibilities in the SRP or organize a new element to perform the (2-['.Yn-
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the resolution of this problem.
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A second potential problem area is related to estimating the scope and extent of effort required to complete Phase II concerring the potential revisions to the SRP and the development of criteria and procedures for use by applicants in their design and review of plant designs for systems interaction.
Therefore, it is anticipated that at the completion of Phase I, a reassessment will be made of the follow-on effort.
It is expected that the information generated by completion of Phase I will provide a valid basis for a reassessment of the balance of effort to complete the task.
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j ATTACHMEt1T 2 SAf401A LAECRATORIES TASKS The following is a brief description of the tasks that will be accomplished by Sandia Laboratories under a contract to the Nuclear Regulatory Commission and administered by the Office of Standards Development.
Task 1.
Define Program Sccoe The scope of the program will vary slightly depending on the undesired event which is being treated.
Theprogram[propesethere)assumesthat K
systems interactions of concern are those which significantly decrease the (pr/X'eNWcw]c/
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Develoo Interaction Descriotion This task would be accomplished by reviewing Licensee Event Reports, interviewing NRC staff members, reviewing relevant literature and draw ng i
from the experience of the study participants.
In this area, particularly, it is hoped that heavy NRC participation will take place.
The methodology will be applicable to a wide range of systems interactions.
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Task 3.
Select Exemolary Facility
,Sandia Laboratories is performing the systems analysis task of the Reactor Safety Study Methodology Application Program.
In this program four plants, representative of the nuclear industry, are being studied and modeled in detail.
It is envisioned that one of these could be used as the exemplary facility.
Such a choice would allow a much smaller manpower requirement to verify and demonstrate the methodology than would otherwise be required.
Task 4.
Review Stancard Review Plan This task will be carried on concurrently with the preceding tasks.
It will include reviewing the Standard Review Plan to assure an understanding of current NRC procedures un the part of the study team.
Task 5.
Develoo Plant Looic Models The system identification techniques used to identify the important combina-tions of systems would be expected to be based on generic LWR plant functional and accident sequence models.
These models would be developed in this task.
They are expected to be similar in physical structure to the event tree models in WASH-1400.
However, for this application they would reflect generic plant functions common to all LWRs and would cover the range of yf, yo/:u w16dk ncl&O conditions which de e d result in failure to shutdown the reactor, remove X
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decay heat, and contain radioactive products.
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Develoo System Models The interaction identification algorithms used to identify potential
' interactions is expected to be based on models of the importar.t systems which themselses will be derived from generic models of LWR plant systems.
These generic models will be developed in the program.
The generic models will be fault trees reflecting combinations of events which lead to system unavailability.
In concept, they will be similar to the generic sabotage fault trees now under development for NRC.
Task 7.
C nneloo System Identification Technicues The techniques developed in this task will become detailed steps in the methodology.
The purpose of the techniques will be to identify the important combination of systems.
The first of the techniques will include comparing the applicant's plant functions and systems against the generic plant logic model.
The usage of generic models in this case is very similar to the usage of the sabotage generic fault tree models.
A sensitivity evalu-ation will be run to identify which combinations of systems for which, if their unavailabilities were not independent but tightly ccupied (i.e.,
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signifirant interactions exist), public safety 4->ukd be significantly affected.
The purposes of this task are to develop the actual techniques to be used, and to define the generic models and associated criteria in such a way that the techniques can be practically applied in the licensing environment.
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09veloo Interaction Identific3 tion Alcorithm The algorithm developed in this task will be based on the generic fault trees.
The design of the plant systems found to be important will be compared with generic fault trees reflecting unavailabilities of that type of system in general.
From this will be derived system unavailability fault trees reflecting thr! applicant's design.
Each event contributing to the uaavailability of each of these important systems will be characterized to reflect such things as:
component type, location, technology, manufac-turer, maintenance procedures, and environmental susceptibilities.
The fault trees of important systems would be compared to identify communali-ties such as similar locations, environmental susceptitilities, etc.
a simplified and " canned" version of the SETS code is envisioned for use in making this comparison.
The purpose of this program task is to develop the necessary algorithms and package them in a manner that they can be practically used in the licensing environment.
Task 9.
Develoo Interaction Imoortant Measures The purpose of this task is to develop the methods of measuring the importance of commonalities or potential interactions identified using the interaction identification algorithm.
Two methods will be explored.
One will ce the development of procedures to prform probabilistic evaluation of the interactions directly.
The second will be to develop generic criteria based on a generic probabilistic evaluatior..
This second approach
' would allow the methodology to be applied qualitatively.
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place, the effect of the interaction on the plant systems, and the importance of the systems to safety.
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Task 10.
Verify and Demonstrate Review Procec The practicality of the review procedure in identifying and evaluating systems interactions is important.
The purpose of this task is to measure that practicality by using the models, procedures, techniques, algorithms and measures on a plant representative of current technology.
Appropriate Licensee Event Reports will be used to assess the applicability and completeness of the methodology relative to adverse system interactions.
Task 11.
Assess Standard Review Man This task will include an assessment of ths Standard Review Plan to determine the completeness of the Plan regarcing identification and evaluation of systems interactions that could poten'ially affect public safety.
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Task 12.
Ptecare Phase I Recort This task will document all work done in Phase I of the program.
Task 13.
Define Phase II Proaram The nature of the Phase II program is dependent upon the outcome of Phase I and the desired level of implementation of the cethodology by NRC.
For
' example, where generic qualitative criteria can be developed reflecting 5
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