ML19284C669
| ML19284C669 | |
| Person / Time | |
|---|---|
| Issue date: | 12/29/1980 |
| From: | Hanrahan E NRC OFFICE OF POLICY EVALUATIONS (OPE) |
| To: | |
| Shared Package | |
| ML19284C670 | List: |
| References | |
| REF-10CFR9.7, TASK-PIA, TASK-SE SECY-80-551, NUDOCS 8101200449 | |
| Download: ML19284C669 (28) | |
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E POLICY ISSUE
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December 29, 1980 SECY-80 551/
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FOR:
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Edward J. Hanrahan, Director
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SUBJECT:
PRELIMINARY POLICY PAPER ON DEVELOPMENT OF A SAFETY G0AL PURPOSE:
1.
To present for Commission consideration a draft State-ment of preliminary policy considerations involved in developing a safety goal, together with underlying rationale. The Statement, if approved by the Commission, will be issued for public comment. The proposed statement is intended to indicate the considerations which may enter into an articulation of the agency's safety goal and require further deliberation, rather than to set forth a single, tentative approach.
The brief draft Statement, intended for publication in the Federal Register, is supported by a more detailed discussion prepared for publication as a separate (NUREG) document. The supporting document, "Toward a Safety Goal: Discussion of Preliminary Policy Consid-erations," referenced in the Federal Register notice, is being submitted to the Commission separately.
2.
To update the program plan for the next phases of work.
SCOPE:
The scope of early policy development efforts has focused primarily on radiological accidents associated with power-reactors.
It is, however, intended to include in later phases considerations of sabotage and other external events for power reactors and to seek adaptation of the safety goal to other facilities and aspects where need is evident.
BACKGROUND:
On October 14, 1980, the Commission instituted a project to develop a safety goal and assigned primary responsibility for the project to the Office of Policy Evaluation (OPE).
An Inter-0ffice Steering Group was appointed to work with OPE. The Commission requested OPE to submit for the Com-mission's consideration a preliminary policy paper, along with a proposed preliminary Commission statement, by December 29, 1980. This paper responds to that request.
8101200 N ege (OPE)
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In accordance with the project plan, the enclosed Statement of preliminary policy considerations, after Commission approval for release, will be issued for public comment, along with the supporting NUREG document.
A policy paper reflecting further work under the project and including alternatives for meeting the Commission's objective of articulating a safety goal is currently scheduled to be submitted by August 12, 1981.
The plan for developing a safety goal was published as NUREG-0735 (and in the Federal Register, at 45 FR 71023).
The present paper reflects the result of an exploratory work phase (described below, under " Methods of Approach").
Pertinent literature and results of recently completed related efforts were taken into account.
Notable among related work items completed since project inception are the ACRS report, "An Approach to Quantitative Safety Goals for Nuclear Power Plants" (NUREG-0739) and " Approaches to Acceptable Risk: A Critical Guide," by Decision Research (Paul Slovic et al.), done under the cognizance of the NRC Office of Nuclear Regulatory Research.
(NUREG/CR-1614 - ORNL/Sub-7656.)
As background for the current policy development efforts, the NRC Historian has, at our request, prepared a draft paper on "The Safety Goal Issue in Historical Perspective,"
which traces the career of that issue -- and some factors in its elusiveness -- through the phases of nuclear safety regulation by our agency and its predecessor. The paper is being submitted for your information separately.
There has been no change in the status of safety-goal legislation since the Commission instituted the safety-goal project.
(As reported in NUREG-0735, the Senate's NRC Authorization bill for FY 1981 would provide for NRC to develop a safety goal and report to the Congress by June 30, 1981, but there has been no corresponding action by the House.)
DISCUSSI0*l:
1.
Method of Approach The early phases of the effort are being conducted with a view toward characterizing the domain of potentially useful approaches and perspectives with a comprehensive sweep. The intent is to create a wide enough starting base for later narrowing down to a few structured alter-natives -- and perhaps one recommended approach. The methods employed in the work to date have included the following:
.. Interviews with Commissioners, to gain the benefit of their preliminary thoughts and advice.
. Twelve separate exploratory discussions with individuals or small groups (two to four people), drawn from industry, nuclear-critic groups, and elsewhere, in order to obtain their preliminary thoughts and views. The interviewees in these discussions were people known to have done work in the safety-goal area or believed able to add to the range of perspectives that we were seeking. After review and correction by the interviewees, reports on these interviews were placed in the Public Document Room.
The interviews have been used indirectly to add to our perspective and stimulate our early thinking about the issues involved.
. Consideration of inputs from relevant work, including background studies, done by or through various NRC groups (ACRS, RES, NRR, Historian).
(Summaries of these studies are being submitted separately for the Commission's information.)
. Background literature and recent papers of non-NRC origin proposing approaches.
(Recent sources included the Atomic Industrial Forum, Electric Power Research Institute, and General Atomic.
These papers are cited where pertinent in the draft Statement and supporting NUREG documents.)
. Preparation of working papers on (a) criteria by which the quality of a potential approach to safety-goal formulation may be judged and (b) alternative approaches (frameworks) for safety-goal formulation.
These working papers are reviewed by the Inter-Office Steering Group on Development of a Safety Goal.
Steering Group members' comments and counsel were taken into account.
. Consideration of public comments concerning the safety-goal plan (NUREG-0735).
(The very few comments received were placed in the Public Document Room.)
2.
Scope and Structure of the Draft Statement The proposed Statement of preliminary policy considerations is presented in Enclosure 1, as part of a draft Federal Register Notice.
The Statement is preceded in the Notice by a preface soliciting public comment on it.
Beside generally inviting comments on the Statement and the supporting NUREG document which it references, the Notice
. also solicits comments on specific Additional Questions, located at the end of the Notice, after the Statement.
The Statement of preliminary policy considerations itself has six parts:
(1) First, there is an introduction. This gives the background of the Statement and its place in the Commission's plan to develop a safety goal. The purpose and scope of the Statement are described; the stated purpose is to indicate the kinds of consider-ations which may enter into an articulation of the Agency's safety goal and require further deliberation, rather than to set forth a single tentative approach.
The introduction goes on to explain the logic of the organization of the Statement.
(2) After the introduction, the Statement turns to criteria for selecting an approach. A set of suggested criteria for the next phases of the program is presented.
These criteria are stated tentatively and alternative formulations of criteria are referred to. Weight assignments are left open.
The criteria themselves are among the topics on which public views are solicited.
(3) Possible approaches to safety-goal formulation are then discussed, successively from several different standpoints.
First, there is a discussion of possible types of safety goals. An analysis of types of quanti-tative goal-setting approaches follows; then the special subject of alternative ways of dealing with uncertainty in verification of compliance with quanti-tative goals is addressed.
Finally, there are brief discussions of two special topics on balancing different sorts of values:
(a) individual and social risk 3 and (b) safety and economic values.
(4) The next section refers to the description of specific safety-goal proposals in the supporting NUREG document.
Particular prominence is given to the proposal submitted to the Commission by the ACRS on October 31, 1980, and described by the Committee as "a preliminary proposal for a possible approach to quantitative safety goals... intended to serve as one focus for discussion on the subject... and... expected to be
... a first step in an iterative process." The ACRS proposal is the only safety-goal proposal that has so far been formally presented to the Commission for consideration or discussion.
The ACRS proposal (for which the NUREG document uses the ACRS's own summary statement) is followed in the NUREG document by the essential elements of five other specific proposals
. that have been elaborated in varying degrees for intended use in the United States, and have been published or widely comunicated.
These six specific proposals represent only a portion of the spectrum of possible approaches. Observations introducing this section of the Statement note particularly the facts and implications of certain common features of the proposals, notably that all address quantitative overall goals and depend on probabilistic risk assessment, though in different ways.
(5) The subject of the Statement's last substantive part is degree of safety.
It points out (a) that the essence of a safety goal is the degree of safety that it establishes, (b) that the Comission's purpose in exploring alternative approaches to goal formulation is the creation of a vehicle for specifying the degree of safety sought in a way that would be meaningful and useful, and (c) that the Comission reserves judgment about any specific degree of safety, pending further progress in its safety-goal development efforts.
(6) There is a brief concluding note about the Commission's intended use of the public comments received.
The purpose of the Additional Questions following the Statement is to draw prospective commenters' attention to significant and difficult specific issues in safety-goal formulation, in the hope of thereby enhancing the value of the public coments in the agency's further safety-goal development efforts.
3.
Procedural Options We do not at this time address the form of any Commission action. A number of options exist, such as:
. A policy statement
. Rulemaking
. Policy statement followed by rulemaking
. Legislative recommendations
. A tentative policy statement, for interim use on a trial basis in some specified manner, to be followed by a more definitive form of action after the planned trial period
. Indefinite deferral of adoption of a safety goal (while retaining the indirect benefits'of illumination of the issue contributed by the process of seeking safety-goal articulation).
. We believe that the procedural options will be ripe for Commission consideration in conjunction with the policy paper scheduled for completion by August 12, 1981.
Accordingly, in cooperation with the Office of the General Counsel, we plan to develop an option paper on the subject as part of the August 1981 policy paper " package."
4.
Update of Plans We are finding the following program adjustments to be necessary.
(The adjustments relate to tasks and milestones in NUREG-0735, the original plan for the project.)
. We now believe that the Workshop on Frameworks, originally considered for February 1981 should be delayed to March.
The delay is necessary to accommodate the activities that must come between this Statement of preliminary policy considerations and the Workshop. These include:
(a) Commission review and action on the paper, (b) preparation of the information package for Workshop participants on the basis of the Commission-approved paper, and (c) study of the information package by the girospective participants in preparation for the Workshop.
We e a now proceeding on the assumption that the Commission will t four weeks sufficient to complete action on this -
we.
. We are finding it desirable to remain somewhat flexible in the detailed planning of the background studies. A good deal of outside related activity is expected to contribute background information sought; we plan to structure the use of our background-study resources to avoid overlaps and to focus on gap filling and.providing needed additional perspectives as the scope and limitations of inputs available (or expected) from elsewhere become evident.
RECOMMENDATIONS: We recommend that the Commission:
1.
Approve the Statement of preliminary policy considerations for issuance for public comment.
2.
Note that, upon approval:
- a. The enclosed Federal Register notice and accompanying Statement and Additional Questions (Enclosure-1) will be issued.
- b. The supporting NUREG document, "Toward a Safety Goal:
Discussion of Preliminary Policy Consider-ations," being submitted separately for Commission review, will be published, after such revisions as may be necessary to reflect Commission comments.
. c. The Statement will be included in the NUREG document (in addition to its publication in the Federal Register).
- d. The Office of Congressional Affairs will notify appropriate Congressional committees.
- e. The Office of Public Affairs will issue a press release.
- f. The Statement and its supporting NUREG document will be used as a principal basis for discussion at the Workshop on Frameworks and at the planned public meetings.
3.
Note that OPE, continuing to work with the Inter-UTTTce Steering Group on Development of a Safety Goal, will proceed with the conduct of the remaining work leading to submittal of a policy paper for Commission consideration by August 1981.
COORDINATION:
The Inter-0ffice Steering Group on Development of a Safety Goal reviewed a draft of this paper.
Steering Group members' comments were considered.
Concurrence of this Group was not sought.
Enclosure:
1.
Draft Federal Register notice (including draft Statement)
Commissioners' comments or consent should be provided directly to the Office of the Secretary by c.o.b. Wednesday, January 14, 1981.
ED0 or Commission Staff Office comments, if any, should be submitted to the Commissioners NLT January 7,1981, with an information copy to the Office of the Secretary.
If the paper is of such a nature that it requires additional time for analytical review and comment, the Commissioners and the Secretariat should be apprised of when comments may be expected.
This paper is tentatively scheduled for affirmation at an Open Meeting during the Week of January 19, 1981.
Please refer to the appropriate Weekly Commission Schedule, when published, for a specific date and time.
DISTRIBUTION Commissioners Commission Staff Offices Exec Dir for Operations ACRS ASLBP ASLAP Secretariat
DEVELOPMENT OF A SAFETY GOAL -
PRELIMINARY POLICY CONSIDERATIONS In accordance with its previously announced Plan for Developing a Safety Goal (45 FR 71023, October 27,1980), the Nuclear Regulatory Commission
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hereby publishes for public coment a preliminary statement of policy con-siderations concerning that subject. A detailed discussion supporting this statement is being published separately as NUREG-
"Toward a Safety Goal: Discussion of Preliminary Policy Considerations." A copy of NUREG-is available for inspection at the Commission's Public Document Room, 1717 H Street, N.W., Washington, D.C.
Single copies of NUREG-are available upon request and at no cost to persons who wish to comment; requests should be made to the NRC-GP0 Sales Program, Attention:
Sales Manager, Division of Technical Information and Document Control, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555 (Phone 301-492-9530).
Copies may also be purchased from the NRC-GP0 Program and the National Technical Information Service, Springfield, Virginia 22161.
Comments on the statement and on NUREG-will be considered in work leading to the preparation of a policy paper for submittal for Commission consideration.
That work includes further studies, public meetings, and workshops.
Salient activities will be publicly announced in order to secure broad participation.
(For a description of that further work, see NUREG-0735, included in 45 FR 71023, October 27, 1980.)
Comments and suggestions are solicited concerning the entire subject matter of this statement and NUREG-or any of their aspects.
In addition, the Commission solicits comments on certain additional, specific questions appearing at the end of this notice.
Written comments should be addressed to the Secretary of the Commission, U.S.
Nuclear Regulatory Commission, Washington, D.C. 20555, Attention:
Docketing and Service Branch, and should be received by
, 1981.*
For further information:
Contact Mr. George Sege, Office of Policy Evaluation, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, (202) 634-3295.
Dated at Washington, District of Columbia, this day of 1981.
For the Nuclear Regulatory Commission.
Samuel J. Chilk Secretary of the Commission
- 60 days after publication in FR.
PRELIMINARY POLICY CONSIDERATIONS I.
INTRODUCTION A.
Background
In accordance with the Plan for Developing a Safety Goal (NUREG-0735; also published in 45 FR 71023, October 27, 1980), the Commission is issuing for public comment this preliminary statement of considerat'ons involved in developing a safety goal.
In accordance with further provisions of the Plan, the comments received on this preliminary statement will constitute a part of the considerations leading to preparation of a policy paper, including a dra't policy statement.
This paper will be prepared by the Office of Policy Evaluation and is scheduled to be submitted to the Commission for its consideration in August 1981.
Subsequently, the Commission intends to seek additional public comment on the proposed policy statement to ensure that public views are accurately and adequately reflected.
B.
Purpose and Scope of the Preliminary Statement The purpose of this preliminary statement is to elicit comments by indicat-ing the kinds of considerations which may enter into an articulation of the Agency's safety goal and require further deliberation, rather than to set forth a single, initial policy, however tentative, as a basis for discussion.
SEGE A/2 2
The scope of early policy development efforts has focused primarily on radiological accidents associated with power reactors.
It is, however, intended to include considerations of sabotage and other external events and to seek adaptation of the safety gcal to other facilities and opera-tions where the need is evident.
C.
Organization of the Statement The articulation of a safety goal must not only stipulate a required degree of protection that is sound, but must also be formulated in a way that is useful in a practical, regulatory sense, in a way conducive to achieving the goal.
This preliminary statement of policy considerations begins with a discussion of the criteria by which the quality of a candi-date approach to safety goal formulation may be judged.
The statement next discusses alternative approaches to safety goal formu-lation.
The discussion includes types of safety goals, types of quantita-tive approach, approaches for dealing with uncertainty, and comments about some aspects of balancing of risks and of safety and other values.
Presented next are references to some specific safety goal proposals.
These include a proposal recommended to the Commission for preliminary consideration as an option by the Advisory Committee on Reector Safeguards and five other proposals known to the Commission.
SEGE A/2 3
Finally, there is a short discussion of degree of safety, since all or most of the potential approaches can be adapted to establishing a degree of protection at any level over a wide range of possible levels.
Selecting that level on a sound basis is, of course, the paramount objective of the effort to develop a safety goal.
II.
CRITERIA FOR ASSESSING AN APPROAC!i TO A SAFETY GOAL Since the range of possible concerns and criteria is great, an approach which does not recognize and accommodate the complexities of the nuclear safety issue is unlikely either to achieve an appropriate safety goal or to convince anyone that it has done so.
Thus, an approach to developing a safety goal requires a set of criteria to assess and validate it.
Such a set of criteria can be stated, ordered, and emphasized in various ways, as discussed in NUREG While several sets of criteria have been proposed, there is not a wide divergence of opinion among the pro-posers on the key criteria.
Authors have named and stated their proposed criteria somewhat differently, but the proposals are similar in essentials.
Drawing c,,, these proposals, a set of criteria for assessing an approach to a safety goal is given below.
As far as we can now determine, these represent the key criteria on which there is apparent agreement.
The following description is brief since we do not foreclose additions, deletions, and changes to the formulation; but we do consider this formulation as appropriate for the next phases of our program to develop a safety goal.
SEGE A/2 4
Suggested Criteria:
1.
Comprehensive - The approach should accommodate a broad problem definition addressing the significant risks of social concern, including early and delayed fatalities, injury, and economic effects.
2.
Logical - There should be a clear and justified decision rule which produces coherent and rational results.
3.
Verifiable - The approach should make it possible to establish the relation-ship between the performance of a facility or operation and the safety goal, in order to measure or otherwise determine compliance.
An approach must be clear in its underlying assumptions, philosophical roots, matters included and excluded, inputs required, analytic methods, and uncertain-ties as well as lead to actions consistent with the goal.
4 Practical - It must address and lead to the resolution of real problems by real people within real resource constraints.
Moreover, the approach should be compatible with social interests and institutions.
It should not require drastic changes in the usual operations of the institutions involved in its implementation, but it should also be able to influence those operations, where necessary, toward the implementation of the safety goal.
5.
Publicly Acceptable - The application of the approach should be a process that is sensitive to and accounts for people's views and ensures their early and continued participation.
SEGE A/2 5
III. APPROACHES TO SAFETY G0AL FORMULATION An approach to developing a safety goal presupposes the existence of and compliance with a set of criteria which validate it.
It also presupposes its competence to address the complexities of the issue of nuclear safety and of assessing a proposed safety goal or amending an existing one.
These presumptions allow a wide range of possibilities, however, since approaches may differ in method, form, and emphasis, and be formal or informal, simple or complex, in their application to the issue before them.
In this section, discussions progress from a characterization of possible safety goal forms, to an examination of types of quantitative approaches, to a brief account of means of dealing with uncertainty, and, finally, to comments about balancing disparate values.
A.
Safety Goal Forms A safety goal can take a number of possible forms and the selection of the goal form can have important consequences to risk management decisionr. fafety goal forms have been classified according to seven pair 3 ? f <. intrasting characteristics which are given below.
(Based on Ma+ tsoi... al., 1980, See NUREG
'N' for.furtherdiscussion.): Ne do not believe the time is ripe nor the state of knowledge sufficient to choose among these; therefore,the next steps in the goal development program
SEGE A/2 6
should address these characteristics.
The seven pairs of characteristics, with brief comments, are as follows:
1.
Single vs. Multiple Goals - Advantageous combinations may be possible, consisting of an interrelated hierarchy of overall and lower-order goals.
2.
Quantitative vs. Qualitative Goals - Overall quantitative goals introduce severe verifiability problems with respect to low-probability high-consequence events.
On the other hand, qualitative goals may defy assignment of clear, ascertainable meaning.
Different specific aspects of safety goal formulatic may Le better suited to one or the other of these alternatives, o.' may be expressible in forms combining qualitative and quantitative elements.
3.
Ends-Oriented vs. Process-Oriented Goals - Ordinarily, goals are thought of principally as ends to which strategies and resources are directed.
A process-oriented alternative focuses on procosses that command confidence.
For example, the implication of Admiral Rickover's comments concerning the basic reactor safety principles of the Naval Nuclear Propulsion program is that if the means of providing for nuclear safety are pursued with the goal of excellence of perform-ance, then acceptable safety will be attained.
SEGE A/2 7
4.
Absolute vs. Relative Goals - Some comparative analysis must underlie relative goals, though comparisons may be fraught with considerable difficulties.
5.
Individual vs. Society-Oriented Goals - In the NRC regulations (10 CFR Parts 20, 50/ Appendix I, and 100), both individual and societal goal forms are used in complementary fashion for limiting radiation exposure.
6.
Site (or Region) Dependent vs. Site (or Region) Independent Goals -
Location may affect the probability of a serious accident, the probability of a failure of a reactor containment, and the radiation exposure of people in event of an accident.
7.
Time-Related vs. Atemporal Goals - A time related goal may call for achievement of some specified safety standard by a specified year and a more stringent safety standard by some later year.
Also, a goal may be interim or settled (though even a " settled" goal may need to be changed, because of technological progress, new informa-tion, or new perceptions).
An interim goal may offer a trial period.
B.
Types of Quantitative Approach Recent efforts towards development of proposed safety goals have had a predominantly quantitative emphasis, notwithstanding evident problems of verification of compliance with any quantitative goals.
The Advisory
SEGE A/2 8
Committee on Reactor Safeguards (ACRS), as background for its own develop-ment of a quantitative approach, accepted a survey of some proposals pre-viously presented in the United States and abroad, according to which such approaches can be roughly categorized into three groups:
those that set limits on individual risk of death only; those that consider frequency of accidents and magnitude of the consequences; and those that imbed the criteria in risk management frameworks that, at least in part, consider
- risks from alternatives or other societal endeavors (NUREG-0739, Part 1).
Some highlights about each type of approach follow.
1.
Individual Risk Criteria - An example is.an early British. suggestion (Adams and Stone, 1967) that an incremental increase in an individual's chance of death per year that is smaller than the demographic variation in the United Kingdom of that chance would be inappreciable and acceptable on those grounds.
2.
Frequency-Consequence Approaches - A basic common assumption in variants of this approach is that the limiting frequency of a particular accident should depend in some way upon its severity.
3.
Risk Management Approaches - Two common premises of risk management approaches are that society nas limited resources to allocate to the reduction of the risks that accompany the benefits of its endeavors and that these resources should be allocated wisely.
Such approaches reflect concern that improper actions to reduce risks may not minimize risk and may even give rise to an increase in overall risks.
SEGE A/2 9
Okrent and Whipple (1977) described a quantitative approach to risk management which incorporated as principal features risk assessment, graduated limits on individual risk, internalization of residual risk costs, modest risk aversion (i.e., an extra penalty, albeit a modest one, for events of severe consequences even at low probability),
and cost effectiveness as the criterion for possible further reduction of a contingently acceptable residual risk.
C.
Approaches to Dealing with Uncertainty - Verifiability of whether a nuclear plant meets an overall quantitative safety goal is subject to both reducible and irreducible uncertainties surrounding probabi-lities and consequences of severe but low probability accidents.
Various approaches can be considered for mitigating the impact of those uncertainties.
We describe five approaches:
arbitration, modeling, restrained use of quantitative criteria, conservatism, and non quantitative approaches.
Combinations of approaches are, of course, possible and may well have merit.
1.
Arbitration - The decisions about whether a goal is met can be entrusted to a group of specially empowered experts.
2.
Modeling - Verification could be tied to a prescribed mode of cal-culation.
SEGE A/2 10 3.
Restrained Use of Quantitative Criteria - Use of the top-level probability target can be limited to decisions concerning the clearly prohibitive and the clearly trivial outliers.
Another mode of restraint is to use an overall plant target only loosely and to provide some general guidance for setting quantitative targets at the level of systems and equipment for which failures can be tolerated with a frequency sufficient for possible verification.
4.
Conservatism - Conservatism can be embedded in the calculations or explicitly applied to risk estimate results.
In the " embedded
approach, estimates of actual risk are based on conservative assumptions, in order to increase assurance that decisions concern-ing the issue at hand will be on the safe side.
As an alternative, one can require calculations to be realistic --
the best one can do.
Margins of due prudence would be introduced into administrative decisions.
Sensitivity analyses may help discern the consequences of alternative judgments and thus help to set an appropriate margin.
5.
Nonquantitative Approaches - Nonquantitative approaches available to reduce vulnerability due to uncertainties inclede independent lines of defense; use of requirements known to be beneficial, though not quantitatively; extra circumspection when abandoning known, established practices for promising innovations; and professional judgment, with emphasis on the qualifications and experience of decision caters and advisors.
SEGE A/2 11 D.
Approaches to Balancing of Values Much of what has preceded in this statement has reflected consideration of disparate and sometimes conflicting values involved in development of a safety goal -- ethical, political, and economic values, along with technical considerations.
As the work of safety goal development progresses, we plan to address the philosophically complex and demanding task of seeking a sound balancing of the values relevant to goal setting.
At this time we limit our dis-cussion to noting in a preliminary way two specific topics:
(1) individual and social risks and (2) safety and economic values.
1.
Individual and Social Risks - A safety goal may focus on the risk of death or illness to which any one individual may be exposed, including permissible differences among individuals in different circumstances, such as workers, nearby residents who may receive some benefit as compensation for incremental risk, and the general population.
The goal may also include consideration of the numbers of people exposed to a risk.
Social risk considerations also include such issues as equities of distribution of risks and benefits, possible transfer of risk to future generations (through long-lived radioactive materi.11s),
distinctions between prompt and delayed fatalities, and whether and how property damage risks (which may indirectly entail other health-and-safety risks) should be taken into account.
SEGE A/2 12 A special aspect of the social risk issue is. involved in the concept of risk management, that is, whether and how to consider the risks of alternatives in setting a nuclear plant safety goal.
2.
Safety and Economic Values - Safety and economic values are not necessarily or invariably in conflict.
Safety may protect plant investment and property of others as well as save medical and other costs of illness.
In this positive respect, the issue is the extent to which economic incentives for safety should be reflected in safety goal formulation.
However, in many questions about safety, safety and economic values conflict or appear to conflict; the issue then involves, first, whether under the circumstances at F.and economic impacts can be taken into account in a safety decision and second, what amount of resources may be devoted (or what benefits foregone) to achieve a particular safety goal.
Decisions concerning possible retroactive applications of new require-ments may involve special safety-cost trade-offs since the costs of specific safety improvements for plants already being built or operating may be substantially higher than for plants yet to be built.
IV.
SOME SAFETY-GOAL PROPOSALS NUREG-describes six safety goal proposals, all urging a quantitative formulation of safety goals and suggesting specific numerical values for the parameters that they propose.
The diverse frameworks can, however,
SEGE A/2 13 be employed in conjunction with numerical values that differ from those suggested in the specific proposals.
The intellectual task of devising a sound framework and the policy task of setting appropriate levels are distinct, though they must in due course merge.
Both tasks are essential, as is their proper merging.
All six of the proposals are based on the use of probabilistic risk assessment. They depend for their effectiveness on the potentialities of that technique and are subject to its limitations - gaps and uncertainties in data bases and difficulties of constructing adequate sets of underlying assumptions and of accounting for human factors in safety.
Some of the approaches proposed include provision for accomodating or mitigating the effects of uncertainties.
With all the approaches, consideration would have to be given to (a) the appropriate role for other methods where probabilistic risk assessment cannot dependably resolve an issue and (b) problems of transition from current practices, including decisions with respect to possible retro-active application of new requirements, as well as (c) the development of sufficiently wide availability of an adequate level of expertise in the new probabilistic methods.
The proposals described in NUREG-include one submitted to the Commission on October 31, 1980, by the Advisory Committee on Reactor Safeguards and described by the ACRS as "a preliminary proposal for a possible approach to quantitative safety goals... intended to
SEGE A/2
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14 serve as one focus for discussion on the subject... and... expected to be... a first step in an interative process."
(NUREG-0739, "An Approach to Quantitative Safety Goals for Nuclear Power Plants," ACRS, 1980.)
The ACRS proposal is the only safety goal proposal that has been formally presented to the Commission for consideration or discussion.
However, we are aware of other proposals relating to development of a safety goal for use in the United States that have been elaborated in varying degree and have been published or widely communicated.
Five such proposals are discussed briefly in NUREG Their sources are the Atomic Industrial Forum; Dr. Chauncey Starr, of the Electric Power Research Institute; Dr.
Vojin Joksimovic, of General Atomic; Dr. Edwin Zebroski, of the Nuclear Safety Analysis Center; and Mr. Robert Bernero, of the NRC Office of Nuclear Regulatory Research.
V.
DEGREE OF SAFETY The essence of a safety goal is the degree of safety that it establishes.
The generic discussion of approaches to safety goal formulation and of the criteria by which approaches may be judged has as its purpose the creation of a vehicle for specifying the degree of safety sought in a way that would make it meaningful and useful.
The assignment of specific proposed degrees of safety in the specific proposals summarized above illustrates the use of the proponents' frame-works and the degrees of safety suggested by the proponents as appropriate.
SEGE A/2 15 The Commission reserves judgment about any specific degree of safety, pending further progress in its safeti goal development efforts.
CONCLUDING NOTE After the Commission receives comment on the preliminary papers on the develop-ment of a safety goal, it will conduct further studies and hold public meetings and workshops.
The Commission expects that this additional information and advice will help it formulate an appropriate safety goal.
SEGE A/2 16 ADDITIONAL QUESTIONS The Commission solicits comments and suggestions concerning the entire subject matter of the preliminary statement of policy considerations and the supporting discussion paper or any parts of that subject matter.
In addition, comments are solicited concerning the following specific questions:
1.
(a) Among the criteria for selection of an approach to safety goal formula-tion that are presented, which are particularly important? Unimportant?
(b) Should additional or different criteria be considered? What criteria and with how much emphasis?
2.
Which of the following are particularly important to include in a safety goal:
(a) Some general approach to risk acceptability?
(b) Quantitative safety goals?
(c) Qualitative --even subjective -- standards?
(d) Approach to safety-cost trade-offs?
(e) Goals for future safety improvements?
(f) Standards for determining when new requirements should be applied retroactively?
3.
'a) A ng the approaches to safety goal formulation that are discussed, w.d wpioach or combination of approaches is particularly appropriate?
Inappropriate? Why?
SEGE A/2 17 (b) Should any other approach be considered? What approach?
4.
(a) Among the approaches to dealing with uncertainty that are discussed, what approach or combination of approaches is particularly appropriate?
Inappropriate?
(b) Should any other approach be considered? What approach?
5.
What should be some of the characteristics of safety requirements:
(a) What should ba the role of safety-cost trade-offs?
(b) To what extent should benefits of nuclear power, absolute and relative to alternatives, enter safety requirements decisions?
(c) to what extent is it appropriate for requirements for new and previously approved plants to differ?
(d) Should a safety goal be applied directly to cases in order to attain a similar degree of safety from case to case (even though that may result in specific design and operation requirements differing according to circumstances)? Or should the goal be applied generically and have requirements, rather than estimated degree-of-safety results, be uniform?
SEGE A/2 18 (e) To what extent should the goal reflect protection of individuals regardless of numbers of persons affected, and to what extent should it reflect total, integrated population or societal effects?
(f) To what extent should equities of distribution of benefits and adverse impacts influence requirements?
(g) Should the safety goal reflect increased aversion to risk of high consequences even at low probability?
(h) What is the proper balance between stability of requirements and flexibility for modification as knowledge develops and insights change.
6.
(a) How should the stringency of nuclear power-plant safety requirements compare with current practice?
(b) How should stringency of the safety goal compare with risks accepted from other (non-nuclear) electrical energy surces and with risks arising in various other contexts?
7.
The Commission invites comments on the ACRS proposal and on the other specific proposals described in the paper, and would welcome any alterna-tive proposals or suggestions.