ML20044D804
| ML20044D804 | |
| Person / Time | |
|---|---|
| Issue date: | 05/14/1993 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| SECY-93-134, NUDOCS 9305200315 | |
| Download: ML20044D804 (8) | |
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4 May 14, 1993 POLICY ISSUE (Information)
FOR:
The Commissioners FROM:
James M. Taylor Executive Director for Operations
SUBJECT:
STATUS OF RISK HARMONIZATION WITH THE ENVIRONMENTAL PROTECTION AGENCY UNDER THE 1992 MEMORANDUM OF UNDERSTANDING PURPOSE:
To provide the Commission with a status report on the staff's efforts to explore risk harmonization with the Environmental Protection Agency (EPA) under Section D of the March 1992 Memorandum of Understanding (MOU).
SUMMARY
The March 1992 MOU represents a major step forward to foster cooperation between the Nuclear Regulatory Commission and EPA in carrying out agency mandates to protect the public health and safety and the environment on matters related to radiation in the environment. The M00 is essential for constructive interactions between the agencies because it establishes a framework for:
(1) resolving issues of mutual agency concern; (2) avoiding unnecessary duplication of regulation; and (3) focusing priorities on the most significant safety and environmental problems. The MOV also includes an important provision (Section D) calling for NRC and EPA to actively explore ways to harmonize health risk goals and to cooperate in developing a mutually agreeable approach to health risk assessment methodologies for radionuclides.
Risk harmonization is a critical activity under the MOU because differing risk management approaches have been a root cause in areas of disagreement between the two agencies.
NOTE:
TO BE MADE PUBLICLY AVAILABLE
Contact:
Michael F. Weber, NMSS y $f g$"
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0" 504-1298 m
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4 The Commissioners NRC and EPA are actively pursuing health risk harmonization both in a generic manner and through ongoing cooperative activities to resolve specific issues in program areas. T>e agencies have completed a comparison of risk assessment approaches. Based on the results of this comparison, there appear to be no-significant differences between the agencies in risk assessment approaches that would influence ultimate decisions, other than in the area of high-level waste management. A similar comparison of risk management approaches is currently in progress.
It appears that risk objectives are a fundamental area of disagreement between the agencies. However, it is difficult to compare the objectives with the risk levels achieved because of differences in regulatory approach and multi-layered, defense-in-depth regulations.
NRC and EPA are exploring this issue in both the ongoing comparison of risk management approaches and cooperative activities on specific program issues.
BACKGROUND:
On March 16, 1992, the Chairman and EPA Administrator William Reilly signed an MOV that provides a basic framework for resolving issues of mutual concern that relate to the regulation of radiation in the environment. The MOU J
framework promotes continued cooperation in resolving high-priority issues of concern, with longer-term goals of improved cooperation and exploration of harmonization of risk goals and risk assessment methodologies. The MOU also establishes principles and procedures for avoiding unnecessary duplication of I
regulation and for focusing priorities on the most significant safety and environmental problems.
Staff has previously provided the Commission with detailed plans and objectives for implementing the MOU, including the risk harmonization provision in Section D (SECY 92-165; and the Memorandum from James M. Taylor to Commissioner Curtiss, July 1,1992).
In addition, NRC and EPA staffs met on two occasions to discuss implementation of the MOU. Discussions centered on identifying priority issues of concern for resolution and exploration of risk harmonization.
Based on discussions at these coordination meetings, NRC and EPA agreed that differences in risk objectives appear to be a root cause of the disagreements between the agencies. NRC and EPA also agreed that exploration of risk harmonization is critical to successful interagency cooperation and resolution of interagency disagreements.
DISCUSSION:
NRC and EPA are actively exploring risk harmonization on two fronts.
The agencies are exploring risk harmonization in a generic manner. Concurrent with this generic approach, the agencies are cooperating to resolve a wide range of technical and policy issues that involve significant questions about risk assessment and risk management. These activities provide for ongoing exploration of risk harmonization in a realistic and focused context.
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The Commissioners Generic Acoroach To Risk Harmonization The first phase of the generic approach for exploring risk' harmonization consisted of a comparison of risk assessment approaches used by each agency.
The second phase consists of a similar comparison-of risk management approaches. The' agencies define Risk Assessment to include methods, assumptions, and other considerations involved in quantifying or estimating the health risk associated with a particular activity.
In contrast,-the agencies define Risk #anagement to include.the selection of risk objectives and associated measures to achieve these objectives.
For each phase, the agencies are comparing and contrasting the' approaches used-by each agency, considering a wide spectrum of programs'and applications.
Based on this comparison, the staffs are identifying similarities and.
differences in approaches for risk assessment and risk management. NRC'and EPA have completed the first phase on risk assessment. The examination of risk management objectives and regulatory approaches is in progress.
In profiling risk assessment methods, NRC and EPA agreed that the scope would be broad in terms of program areas and types of assessments. ~Within EPA, the risk assessment profile included the following program areas:
- high-level waste
. low-level waste
- uranium mill tailings l
- indoor radon Superfund a
hazardous and solid waste management
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Clean Air Act programs Safe Drinking Water Act programs Clean Water Act programs l
Examination of the risk assessment methods used by NRC included the following program areas:
decommissioning low-level waste high-level waste a
uranium recovery e
l materials licensing fuel cycle facility licensing l
radiation protection standards l
effluent requirements for reactor facilities
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supporting rulemaking activities.
The staffs identified several different types of risk assessment applications,
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including applications in support of rulemakings, compliance determinations, and event analyses. The staffs focused the comparison on health risk assessment approaches and techniques. The comparison did not consider-engineering risk assessment, which considers the probability and consequences of failure of components and structures, because EPA generally does not I
The Commissioners ~ conduct such assessments. However, staff recognized that differences.in engineering risk assessment could affect regulatory decisions in the high level waste and reactor programs.
On November 25, 1992, NRC and EPA staffs briefed senior agency management on the results of the risk assessment comparison. Staffs identified more similarities than differences in risk assessment approaches used by NRC and EPA. The specific similarities identified through the risk assessment comparison are as follows:
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- Both agencies generally use deterministic Hsk assessment approaches (except high-level waste and nuclear power reactor routine emissions).
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- Both agencies generally assess exposure to a reasonable maximally exposed.
individual and usually consider the same pathways.for exposures.
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- Both agencies translate exposures and intakes into doses and risks using internationally accepted techniques.
- Both agencies assess risk primarily in terms of cancer fatalities.
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- Both agencies sometimes truncate risk assessments.
The staffs also identified the following differences between EPA'and NRC risk assessments:
- For radionuclides, NRC generally conduc'ts site-specific assessments in.
support of compliance determinations, whereas EPA generally conducts generic assessments in support of rulemakings.
NRC conducts some generic assessments in support of rulemakings and EPA conducts site-specific assessments in programs where it has implementation authority (e.g.,
Superfund).
r NRC generally limits individual risk, whereas EPA may place greater emphasis than NRC on limiting population risk beyond individual risk limits.
- NRC has traditionally used radiological dose in rulemaking and compliance assessment, whereas EPA programs generally use health risk as the end point of concern.
- NRC and EPA use slightly different risk coefficients to convert doses into health effect estimates; dose and risk conversion factors may be considerably different for certain radionuclides that emit alpha radiation.
- NRC and EPA have assumed different exposure scenarios for long-term exposure (e.g., radioactive waste disposal).
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4 The Commissioners. NRC generally truncates population doses in terms of time and space, whereas EPA for completeness prefers to assess population risk without truncation in time or space if it affects available control options.
Based on the comparison and relative significance of the. similarities and differences, the staffs concluded that resolution of the differences in risk assessment approaches is unlikely to significantly affect the outcome of agency risk aseessments in most program areas.
Staff believes that significant differences in risk assessment approaches are evident in the high-level waste (HLW) area.
EPA has defined several hypothetical HLW repositories and has evaluated their projected performance in support of its standard-setting activities.
EPA's risk assessment approach is much less sophisticated than the techniques that are expected to be applied by NRC in evaluating compliance with EPA standards and NRC requirements.
For example, EPA is currently using a single " pipe" model to simulate radionuclide transport from a repository to a well located two kilometers away. The simplicity of this model precludes simulation of fractures, potential failure of borehole and shaft seals, or other inhomogeneities in geologic media. The staff believes that the simplicity of EPA's modeling limits the ability to determine whether relatively rapid transport of small amounts of waste might occur, leading to potential violations of EPA's proposed standards.
EPA's risk assessments for these hypothetical repositories largely determine the degree of stringency of EPA's HLW standards.
As an example of the limits of simplistic modeling, early models prepared by EPA and NRC in support of rulemaking in the HLW area overlooked possible release pathways, such as gaseous release of carbon-14. As a result, EPA could establish release limits for HLW disposal that are difficult, if not impossible, to meet. However, the more sophisticated modeling approaches that will likely be used by NRC to evaluate compliance may demonstrate that these individual pathways are unlikely or insignificant. Thus, differences in risk assessment approaches between NRC and EPA could significantly affect risk management decisions in the HLW program area. Similar differences could surface in other programs where risk assessment techniques continue to evolve, such as in EPA's development of standards for low-level radioactive waste management and NRC's development of enhanced performance assessment capabilities.
This comparison of risk assessment approaches has helped the agencies gain a better understanding of each other's internal practices and procedures for estimating doses and risks associated with radiation in the environment. The comparison has also provided the agencies with valuable insights into the companion review of risk management approaches.
Specifically, staff noted that differences between risk management approaches appear to be more significant than the differences in risk assessment. Staff also noted that the risk management comparison would likely prove to be the more critical aspect of the risk harmonization effort because differences in risk management appear to be the underlying cause of disagreement on most issues.
NRC and EPA are currently involved in comparing and contrasting risk management approaches used by each agency. The first step in this process is
The Commissioners to collact and compare information about a variety of risk management attributes across a broad range of NRC and EPA programs.
The risk attributes the agencies have selected include the following:
dose / risk limitation
= regulatory, scientific, and policy bases for dose / risk limitation
- considerations associated with implementing the dose / risk limitation
- mechanisms by which compliance with the dose / risk limitation is demonstrated
= situations in which an exception to a dose or risk limitation would be allowed.
The range of programs being examined is consistent with the programs included in the risk assessment phase. NRC and EPA staffs have completed draft profiles of risk management approaches across each agency's programs.
In addition to its value in risk harmonization with EPA, developing this profile proved to be worthwhile for NRC staff because it illustrated areas of internal NRC inconsistency in risk management approaches. The comparison also helps to preserve some institutional memory for the risk management decisions made in various NRC programs and rulemakings.
NRC and EPA are analyzing the profiles to identify similarities and differences between EPA and NRC risk management approaches in a manner similar to that used in the risk assessment phase. A joint briefing of senior agency management will then be conducted to present the results of the risk management comparison.
After completing the risk assessment and risk management comparisons, the agencies will consolidate the results and conclusions into a White Paper on risk harmonization. This paper will establish the foundation for the agencies to pursue risk harmonization by identifying:
- new opportunities to seek risk harmonization l
= issues that deserve additional exploration l
- priority issues for discussion associated with risk assessment methodologies and risk goals.
NRC has the lead responsibility in preparing the White Paper. The staff 1
intends to prepare a draft of the White Paper by late Summer 1993. Completion of the White Paper on risk harmonization is an important step in implementing j
the M0li provision on risk harmonization because it provides the support and foundation for the beginning of the risk harmonization process.
By identifying new opportunities to seek harmonization and issues that deserve further exploration, the paper will provide a strong and consistent basis for i
future efforts to resolve issues of concern between NRC and EPA.
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c The Commissioners 1 Risk Harmonization throuah Specific Proaram Activities While risk harmonization advances in a generic manner, NRC continues to interact with EPA to resolve areas of disagreement in specific program areas.
In several of these program areas, the remaining unresolved issue with EPA is in the area of risk management. These program areas are as follows:
= Clean Air Act standards for air emissions of radionuclides;
= Radiological criteria for decommissioning;
= Low-level radioactive waste standards; and
= Alternate concentration limits for uranium mill tailings disposal, i
The agencies have identified-the underlying disagreement regarding these four program areas as the level of risk each agency considers to be sufficient i
protection of public health. This difference in the belief of what constitutes sufficient protection results from a fundamental difference between the agencies in regulatory approach, although current information suggests that the level of protection achieved under both agencies' programs is comparable. Assessment of the level of risk actually achieved in the programs is difficult because of differences in regulatory approach and the application of multi-layered, defense-in-depth regulations. For example, NRC's requirements in 10 CFR Part 61 embody a systems-based regulation that includes general performance objectives and a series of technical requirements i
on site suitability, waste characteristics, waste classification, design and operation, environmental monitoring, and institutional controls.
These requirements may collectively achieve a level of protection that surpasses the performance objectives.
In addition, NRC's licensing, inspection, and i
enforcement programs add to the level of protection. Thus, assessments of the j
level of protection associated with NRC and EPA programs need to consider both quantitative and qualitative factors.
EPA frequently establishes ambitious safety goals and then allows operators to achieve a relaxed risk level, to account for technology, cost, or practicality considerations. On the other hand, NRC sets a more pragmatic risk limit, but requires licensees to reduce doses to levels below the established safety limit, through radiation protection programs that employ the principle that doses should be as low as is reasonably achievable (ALARA). Application of ALARA considers cost, technology, and practicality. Although the practical effect of these two regulatory approaches is largely the same, there remains a difference of about a facto [),of 10 between NRC's acceptable lifetime risk l
level of excess cancer (10' as embodied in the publ and EPA's acceptable lifetime risk range (10'{c dose, limit in 10 CFR 20.1301, to 10' ), as described in the National Emission Standards for Hazardous Air Pollutants (40 CFR Part
- 61) and in the Superfund program (40 CFR Part 300).
It is this fundamental difference in acceptable risk and regulatory approaches that the agencies need to explore in seeking harmony in public and environmental protection.
e The Commissioners CONCLUSIONS:
Although the risk harmonization process is still in its early stages, NRC and EPA have reached several important conclusions.
Based.on the comparison of risk assessment approaches, the staffs have concluded that:
- There are more similarities in risk assessment than differences.
- Resolution of the differences in risk assessment approaches is not likely to affect significantly the outcome of agency decisions in most program areas, i.e., the quantitative risk estimates, in.most cases, will not-change significantly after resolution of differences is achieved.
- The most significant differences appear to be in the area of risk management.
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In addition, interactions with EPA to resolve disagreements in specific program areas have highlighted fundamental differences between EPA and NRC. in-regulatory approaches and the level of acceptable risk for protection of-public health and safety.
i The current staff focus is on completing the comparison of risk management approaches. After completing the comparison, the staff intends to prepare a draft of the White Paper on risk harmonization by late Summer 1993. When complete, staff expects that the White Paper will-highlight differences between the agencies and will help identify important opportunities for further risk harmonization.
COORDINATION:
The Office of the General Counsel has reviewed this paper and has no legal objection.
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k J es M. Tayly ecutive Director for Operations DISTRIBUTION:
Conunissioners OGC OCAA OIG OPA OPP EDO SECY l
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