ML20056F707
| ML20056F707 | |
| Person / Time | |
|---|---|
| Issue date: | 08/20/1993 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| SECY-93-232, NUDOCS 9308300290 | |
| Download: ML20056F707 (12) | |
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POLICY ISSUE SECY-93-232 (NEGATIVE CONSENT)
For:
The Commissioners from:
James M. Taylor Executive Director for Operations Subiect:
STAFF APPROACH FOR ASSESSING THE EFFECTIVENESS OF THE PRESENT REGULATIONS WITH RESPECT TO THE COMMISSION'S SAFETY G0ALS Puroose:
To inform the Commission of the staff's approach for evaluating the effectiveness of the existing nuclear reactor regulations with respect to the Commission's safety goals.
Summary:
In two SRMs dated May 10 and June 15, 1990, the Commission requested that the staff develop a plan to evaluate the effectiveness of the present regulations using existing PRA information, particularly the results from the ongoing Individual Plant Examination (IPE) program. After considering a number of
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different alternatives for performing the evaluation requested, the staff recommends an approach using the results from the IPE/IPEEE augmented by information from several other ongoing activities, such as the Regulatory Review Group and the program for elimination of requirements marginal to safety. Other approaches that were considered would be complex and expensive and would still yield results with considerable uncertainty. The staff believes that the information being developed in these ongoing programs will provide at a reasonable cost a useful perspective regarding:
(a) whether the safety level and risk of operating US plants are consistent with the safety goals, (b) whether specific regulations result in over regulation in terms of NOTE:
TO BE MADE PUBLICLY AVAILABLE WHEN THE FINAL SRM IS MADE AVAILABLE
Contact:
Brad Hardin, RES 492-3733 f/T q
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The Commissioners 2
risk, and (c) whether there are gaps or areas in the regulations which need to be addressed.
Backaround:
I Existing regulations for nuclear reactors have evolved over the past 30-40 years.
Government regulators and the industry learned together, often from operating experiences, what specific areas of reactor design and operation were significant from a safety perspective, thereby warranting some form of formal regulation.
But no explicit goal or standard was established.
i Early in the 1980's, independent of the regulations, the Commission and staff began to explore various approaches for judging when a level of safety is reached in nuclear power reactors that is " safe enough." These early efforts resulted in the issuance of the Commission's Policy Statement on Safety Goals in August 1986. The policy statement broadly defines an acceptable level of l
radiological risk from nuclear power plant operation, and sets forth two qualitative safety goals and two quantitative health objectives ("QH0s"). The basic principle followed in the development of the safety goals was that risk to individuals from the consequences of nuclear power plant operation should be small relative to the risk that is endured from other sources.
l While there has been no previous attempt to systematically compare the safety of the total population of nuclear power plants and each regulation with the safety goals using quantitative information, recent proposed regulations and guidance and some individual plants (e.g., NUREG-Il50 plants) have been evaluated.
Furthermore, the topic of the safety goals and their implementation have been discussed at some length within the Commission over the past several years. The results of these discussions are reflected in Commission guidance stated in the SRM "SECY-90-102-Implementation of the Safety Goals," June 15, 1990, memorandum from S.J. Chilk to J.M. Taylor.
Additional Commission guidance and requests for staff recommendations relating to safety goal policy implementation have been issued to the staff. These include a May 10, 1990 SRM that addressed the use of the Individual Plant Examination (IPE) data, an August 26, 1992 SRM regarding the staff's plans for eliminating requirements marginal to safety and a December 24, 1992 memorandum establishing the Regulatory Review Group to conduct a comprehensive and disciplined review of the regulations and related NRC processes, programs and practices for their implementation.
In the June 15, 1990 SRM, the Commission requested (Item 8) that the staff prepare a plan to compare the consistency of the existing regulations with the safety goals. The results of such an assessment would be used to determine whether new or revised requirements are necessary or desirable and whether some current regulations are unnecessarily stringent and could be relaxed or even eliminated. Additionally, in an SRM, dated May 10, 1990, the Commission stated that the staff should continue to explore possible options for using the IPE data to enhance the understanding of the adequacy of our regulations through comparison with the safety goals.
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In an earlier staff paper, the integration plan for closure of severe accident issues, SECY-88-147, May 25, 1988, the planned use of safety goal objectives was described. This use still remains consistent with present Ccmmission guidance in the more recent SRMs cited above.
SECY-88-147 included this statement:
"PRA information from a variety of sources, including staff generated PRAs (e.g., NUREG-1150) and utility generated PRAs (IPE) will be used to make comparisons with applicable safety goal objectives in accordance with the implementation plan. The staff will identify the reasons why particular plants appear to meet or not meet these objectives and assess these reasons in relation to current regulatory requirements.
This assessment will constitute a testing of the effectiveness of these requirements or their im,plementation...."
In a related area, an SRM dated August 26, 1992 gave Commission approval for the continuation of the staff's program to review and revise requirements that are marginal to safety, and directed the staff to keep the Commission informed on plans to more comprehensively apply PRA technology and safety goals to the body of regulations.
In a memorandum for the Commissioners from James M. Taylor, dated January 4, 4
1993, the charter for the Regulatory Review Group was provided.
This activity is also focused on identifying and eliminating regulatory requirements that are marginal yet require substantial utility resources for their implementation.
i On May 13, 1993, the staff met with the ACRS to discuss the subject of this paper. As a result of this meeting, the ACRS provided their recommendations for assessing the consistency of the present regulations with respect to the Commission's safety goals (letter from Paul Shewmon to Chairman Ivan Selin, May 26, 1993, Enclosure 1.) The content of the ACRS letter will be discussed further below.
Discussion:
Over the past several years, the staff has considered several different approaches for carrying out an evaluation of individual regulations with respect to their risk importance and relationship to the safety goals. One of the principal approaches considered included the use of sensitivity studies mainly using NUREG-1150 PRA information. The purpose for the sensitivity studies would be to explore questions such as:
(i) what is the risk significance of certain design features and operational procedures that are explicitly required by the current regulations or may be included in the r
design certification rulemaking for certain advanced LWRs, and (ii) what is the risk significance of two or more regulatory requirements that affect the i
same equipment in the plant, producing PRA results that do not presently allow us to distinguish between the effectiveness of the individual requirements?
If credible information of this nature could be acquired, insights into the relative value of specific regulations and the potential value of making certain changes in the regulations could be provided.
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Based on past experience, pursuing such an approach would be complex and i
involve essentially reconfiguring portions of plant models.
Such model changes would be complex because of the interrelationships that exist between safety and support systems. The result is that considerable care would need to be exercised in making model changes in existing PRAs.
Cases for performing such studies would have to be judiciously selected and performed by qualified analysts. The evaluation of complex design cases would result in relatively large costs as well as significant schedules.
In addition, there would be inherent large uncertainties such that the results may not be sufficiently robust to support regulatory decisions.
Therefore, the use of sensitivity studies to evaluate individual regulations was determined to be impractical because of the uncertain value of the results and the extensive resources that would likely be required to perform the sensitivity studies.
After considering the objectives embodied in the SRMs discussed above and the available information sources and approaches for addressing those objectives, the staff is proposing an evaluation process that would include three basic elements:
(1) assessing the consistency of the safety level associated with the operating plants in comparison with the safety goals thus providing a measure of the overall effectiveness of the regulations, (2) evaluating the existing regulations for marginal requirements that could be either relaxed or removed, and (3) evaluating the regulations for " gaps" - to potentially add or strengthen requirements. Each of these elements is addressed individually
-below.
1.
Comparison of the safety level of operatina US olants aoainst the safety goals.
The IPE/IPEEE insights program will include an assessment of licensee submittals in light of the NRC safety goals, with a particular focus on the subsidiary goals of core damage frequency (CDF) and conditional containment failure and bypass probabilities (CCFP). This will also include a limited assessment using the quantitative health objectives (QH0s). This latter aspect reflects that level 3 PRA information, needed to evaluate consistency with the QH0s, is expected for only about 10% of the operating plants. As a result, there will only be limited opportunity to assess the overall consistency with the QH0s without the staff's expenditure of additional resources to estimate the Level 3 outcomes for the remaining population of plants.
However, this evaluation using the results of the IPE/IPEEE should provide a reasonable perspective of the safety level of the population of US plants compared to the safety goals. This evaluation will also provide a perspective of the effectiveness of the regulations by determining whether the plants safety levels are consistent with or lower than the safety goal risk objectives.
While the safety levels can be assessed using PRA information, it becomes much more difficult to identify the specific source or basis for that level of
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safety. There are three generally independent elements affecting the safety i
of US reactors, viz (a) the NRC regulations and regulatory process including l
inspections and enforcement, (b) the industry's evaluation and analysis programs of NUMARC, INPO, owners groups and vendors, and (c) the individual plant initiatives to improve safety and plant operation. Thus, the focus of the staff's effort will be on assessing the safety level and risk of the plants against the safety goal objectives and surrogate goals and not to try to determine the extent to which NRC regulations 'are uniquely responsible for this result.
2.
Evaluation of existina reaulations for maroinal reauirements that could I
be either relaxed or removed.
The staff is currently implementing a program to evaluate requirements that are marginal to safety and to _ eliminate requirements that are determined to be overly stringent.
The Commission was informed in SECY-93-028, dated February 5,1993, of staff plans for the application of PRA technology and the safety goals in this program. As part of ongoing rulemaking efforts and for the evaluation of other issues in the program to eliminate requirements marginal to safety, the staff plans to develop a methodology for applying PRA technology and safety goals more comprehensively. This will include the development of criteria for determining when a regulatory requirement _is marginal to safety, to develop methods for using PRA to differentiate between the marginal and the significant and essential requirements, and to account for uncertainties and limitations in such analysis methods.
The staff expects that this methodology will be an important vehicle for the study of coherence in regulation. Consideration will also be given to the use of alternative approaches developed by industry such as developed by NUMARC's Regulatory Threshold Working Group. The role of industry and the NUMARC initiative are discussed further below.
A major component of the methodologies for this study will be developed t
through actual applications.
Included are the staff's efforts to develop l
performance oriented and risk based regulations for containment leakage testing and fire protection requirements. The staff plans to use the PRA results documented in NUREG-1150 and available IPE studies to distinguish the requirements in these regulations that have substantial impact on safety from those that are only marginal to safety and could be eliminated or relaxed.
The regulatory safety objectives in these regulations will be addressed based on these analyses and the Commission's safety goals.
The proposed rules for containment leakage testing and fire protection requirements are expected to i
be submitted to the Commission in March 1994 and July 1994, respectively.
The methodology used to develop these proposed rules will be documented in a NUREG report for generic applications.
Further, it is expected that the final recommendations from the Regulatory i
Review Group will highlight potential areas where NRC regulations may be overly restrictive or unnecessary. The report recommendations will be 4
considered and acted upon in many cases through the marginal to safety j
program. Those not incorporated in this program will be acted upon individually by the responsible office.
l The Commissioners 6
i It is also expected that industry will play an important role in identifying and assessing requirements that may have only a marginal impact on safety, but pose a significant economic burden.
The industry has been encouraged to submit petitions to the NRC for rulemaking whenever their studies show that requirements can be relaxed without an adverse impact on safety while providing substantial economic benefits.
In this regard, the staff's proposed Regulatory Analysis Guidelines would require supporting documentation for action that would relax or reduce current requirements sufficient to conclude:
(a) the public health and safety and the common defense and security would continue to be adequately protected if the proposed reduction in requirements or positions were implemented, and (b) the cost savings attributed to the action would be substantial enough to justify taking the action, and the savings would clearly outweigh any reduction in benefits.
3.
Evaluation of existina reaulations for "aaos" to ootentially add or 6
strenothen reauirements.
For this element of the assessment, the IPE/IPEEE insights program will evaluate the major sources and magnitudes of risk to assess potential gaps in the regulations and to determine if further study or regulatory attention is warranted.
In this sense, the IPE/IPEEE program complements the program to eliminate requirements marginal to safety.
In addition to the IPE/IPEEE insights program, the staff has a number of other ongoing activities that are providing useful information on the effectiveness of the regulations, i
particularly with regard to possible " gaps" or areas needing regulatory action. These activities include the Generic Safety Issue resolution program, AE0D evaluations of operational events and data, in-service test and inspection programs, the Accident Sequence Precursor Program and the review of foreign operating experience. These programs are currently being used to identify potential areas in the regulations for improvement and, as with the marginal to safety program and the IPE/IPEEE program, recommendations to revise existing regulations based on information resulting from these programs will be made with consideration of the safety goals.
NUMARC recently informed the NRC of a new initiative by the industry that is important to the effort described in this paper (letter from Joe E. Colvin to James H. Sniezek, dated July 13,1993). This initiative is the creation of the NUMARC Regulatory Threshold Working Group. A stated purpose of the working group is to " Identify and facilitate generic applications of PSA (probabilistic safety assessment) technology in the regulatory process that sustain or enhance current levels of safety and improve plant performance,"
and a goal of the group is to " Consider the NRC's Safety Goal Policy Statement and provide industry input to NRC on revisions to its regulatory analysis guidance." Based on these stated objectives, the staff views the formation of the Regulatory Threshold Working Group as a promising initiative to promote the exchange of ideas between the NRC and the industry on the practical use of safety goals in future regulatory decision making. The staff plans to work closely with NUMARC and industry representatives in this initiat_ive as an important input to the NRC's evolving implementation plans for safety goal policy.
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In performing the three elements of the safety goal assessment, the staff would avoid using the comparisons between PRAs and the safety goals for judging the acceptability of individual plants consistent with the guidance included in the June 15,1990 SRM.
Instead, the results of the comparisons would be used to assess the effectiveness of the regulations. Deterministic information and engineering judgment would also be a part of the basis for deciding to propose any changes to the regulations.
Guidance from the Regulatory Review Group is also expected to influence many of these additional supporting and ongoing staff activities.
Schedule:
It is expected that the IPE data base will be sufficiently established later this calendar year and into 1994 so that the staff can begin drawing insights
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regarding the safety levels and risks of US plants against the safety goal objectives. This approach is expected to be extended during FY 1995 to include the remaining IPE PRAs and the IPEEE submittals.
(IPEEE information is not scheduled to become available until FY 1995.)
The staff's current plans for the program to eliminate requirements marginal to safety call for the submittal of a draft NUREG report containing a continuing program for applying PRA methods and safety goals to the body of regulations for public comment by about December 1994.
The staff will keep the Commission informed as other pertinent information is developed.
In this regard, the Regulatory Review Group assessment is scheduled to be forwarded to the Commission in late August /early September and the recommendations will be considered at that time.
With regard to evaluations of existing regulations for " gaps", these activities are part of ongoing programs, and the need for specific regulatory activities will be determined on a case-by-case basis.
The staff met with the ACRS in May 1993 and the Committee provided its comments to the Commission in a letter dated May 26, 1993. The ACRS expressed a concern that the staff's approach as initially proposed was not completely responsive to the request in the June 15, 1990 SRM.
In response to the ACRS comment, the staff has expanded its plans to make use of the IPE/IPEEE results and other PRA results to assess the existing level of safety that has resulted from implementation of the body of regulations and to compare these results 3
with the safety goals as described above.
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Recommendations:
Unless directed otherwise by the Commission, the staff intends to utilize the results from the major ongoing and complementary programs, as discussed above, to develop insights into the effectiveness of the regulations with respect to the safety goals. The staff believes that the information described will 4
1 The Commissioners 8
provide a reasonably complete perspective as requested by the Commission. 0GC has reviewed this paper and has no legal objection.
\\msM.Tayhr/
E cutive Director for Operations
Enclosure:
As stated SECY NOTE:
In the absence of instructions to the contrary, SECY will notify the staff on Tuesday, September 7,
- 1993, that the Commission, by negative consent, assents to the action proposed in this paper.
DISTRIBUTION:
Commissioners OGC OCAA OIG OCA OPP EDO SECY
i Enc (C6dt Revised:
June 16,1993
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May 26, 1993 n
The Honorable Ivan Selin Chairman U.S.
Nuclear Regulatory Commission washington, D.C.
20555
Dear Chairman Selin:
SUBJECT:
STAFF APPROACH FOR ASSESSING THE CONSISTENCY OF THE PRESENT REGULATIONS WITH RESPECT TO THE COMMISSION'S SAFETY GOALS During the 397th meeting of the Advisory Committee on Reactor Safeguards, May 13-15, 1993, we discussed a draft Commission paper regarding the staff's proposed approach for assessing the consistency of present regulations with respect to the commission's safety goals.
During this meeting, we had the benefit of discussions with representatives of the staff.
In a Staff Requirements Memorandum (SRM) dated June 15, 1990, the Commission requested that the staff develop a plan "for assessing the consistency of our regulations with the safety goals." This is an effort that the Committee has recommended in several reports, and continues to endorse.
In its presentation, the staff provided a conclusion that a specific new program is not necessary to respond to the SRM.
The staff contends that existing programs, in the areas noted below, are sufficient to make the desired assessment:
Elimination of Requirements Marginal to Safety 1.
2.
IPE/IPEEE Data Base Insights 3.
Other ongoing activities that include:
The Regulatory Review Group Generic Safety Issue evaluations e
AEOD evaluations of operational events and data e
i.
NRR inspection reports Accident Sequence Precursor studies We believe that these existing programs can provide input into the subject program, but are not by themselves responsive to the SRM.
We recommend that a directed effort be undertaken to ake the
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l The Honorable Ivan Selin 2
.May 26, 1993 I
assessments requested in the SRM.
A first step should be to i
develop an assessment strategy to make use of the IPE/IPEEE results i
and other appropriate PRA results to establish the existing level of safety that has resulted from compliance with the body of l
current regulations, to be compared with the safety goals.
The facts that the IPEs are essentially Level 2 PRAs and do not evaluate risk directly, and that seismic and fire events in IPEEEs I
are not necessarily evaluated probabilistically, are formidable l
barriers to their use for assessing the consistency of the present i
regulations with the safety goals.
Nevertheless, these and other l
existing PRAs are the best available information for such ' an J
assessment.
We recommend that the assessment strategy include the development of surrogates for the safety goals, expressed in terms of core damage probability and conditional containment failure i
probability - the outputs of the IPE.
We believe that bounding, i
site-independent surrogates can be developed because, for high t
source terms, the conditional mean individual risk of early
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fatalities approaches a limit of about 0.1, and the conditional mean individual risk for latent fatalities approaches a limit of about 0. 01.
These limits result from the probability that the wind
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will blow in a given direction, i
It is entirely possible that the outcome of such an assessment will f
reveal that the level of risk resulting from compliance with the body of existing regulations is below the safety goal levels of I
risk.
Such a finding would have significant implications.
It is important that such a determination be made.
t Sincerely, f
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Paul Shewmon Chairman I
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Reference:
1.
Memorandum date6 April 18, 1993, from C.
J.
Heltemes, Office j
of Nuclear Regalatory Research, for John T.
Larkins, ACRS, l
Subject:
Staff Approach for Assessing the Consistency of the Present Regulations with Respect to the Commission's Safety-Goals, with attachments:
a.
SRM dated June 15, 1990,
Subject:
Subject:
i Implementation of the Safety Goals l
b.
Draft SECY paper for the Commissioners from James M.
j Taylor, EDO,
Subject:
Staff Approach for Assessing the Consistency of the Present. Regulations with Respect to i
the Commission's Safety Goals (Predecisional) l
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Revised Page
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o The lionorable Ivan Selin 3
May 26, 1993 i
2.
ACRS Report dated April 12, 1988, from W. Kerr, ACRS Chairman, to The lionorable Lando W.
- Zech, Jr.,
NRC Chairman,
Subject:
Program to Implement the Safety Goal Policy -- ACRS Comments I
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 0,
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June 25, 1993 r
The Honorable Ivan Selin Chairman U.S.
Nuclear Regulatory Commission Washington, D.C.
20555
Dear Chairman Selin:
In our report dated May 26,
- 1993,
" Staff Approach for Assessing the Consistency of the Present Regulations with Respect to the Commission's Safety Goals," there was an unfortunate error in wording, which may have caused some confusion.
In the last 1
paragraph the words, " level of safety" should be replaced by " level of risk." We were speaking of safety levels better than the safety
- goals, therefore, lower risk.
We regret the error.
We are transmitting a revised copy of the report to you.
4 Sincerely, f
[.
J.
Ernest Wilkins, Jr.
Chairman
Enclosure:
ACRS report dated May 26, 1993,.from Paul Shewmon, ACRS Chairman, to The Honorable Ivan Selin, NRC Chairman, Revised June 16, 1993,
Subject:
Staff Approach for Assessing the Consistency of the Present Regulations With Respect to the Commission's Safety Goals 6
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