Risk and Decisions About Disposition of Transuranic and High-Level Radioactive Waste (2005) / Chapter Skim
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5 Impediments to a Successful Application of the Risk-Informed Approach
5 Impediments to a Successful Application of the Risk-Informed Approach
Pages 113-138
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From page 113... ...
In this chapter, the committee reviews some of the unavoidable and irreducible complexities in performing risk analysis and other important sources of concern with risk assessments. In order to apply the risk-informed approach successfully, the Department of Energy (DOE)
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From page 114... ...
The goal of the risk analysis in the risk-informed approach described in this report is to inform DOE, regulators, American Indian nations, local governments, and the public of the full range of outcomes that might occur by accounting as much as possible for the limitations of our knowledge of the systems involved. The analysis should inform the process participants of the ways in which undesirable outcomes may occur and provide insight into how to better engineer for or manage those risks.
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From page 115... ...
Although the "risk" associated with disposition of different types of radioactive waste may be judged initially by the properties of the waste (e.g., amount of radioactivity, chemical form, toxicity, half-life, complexity of composition) , the actual risk assessment that is used to evaluate a disposition strategy will involve models of the interaction of the waste components with the nearfield and far-field environments, including interactions with engineered barriers or other containment mechanisms and the natural geochemical and hydrological systems.
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From page 116... ...
In the early 1970s, probabilistic risk assessments (PRAs) were used to evaluate the risk and consequences of nuclear power reactor accidents.
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From page 117... ...
In no sense, therefore, will these models give a single answer to the question of the fate of radioactive waste in geologic repositories.... A quarter of a century later, there is an ongoing debate about the value and limitations of risk assessments (Ewing et al., 1999)
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From page 118... ...
Even when the above issues are addressed carefully and the input data are as good as the current state of knowledge allows, uncertainty in the analysis will remain. The final risk assessment will still be model dependent, and conceptual model uncertainty will be a concern.
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From page 119... ...
Often analysts believe that this means that the risk assessment must be performed probabilistically. However, probabilistic analysis can increase the complexity and opacity of the analysis, yet distract from the most important form of uncertainty: conceptual model uncertainty.4 NRC (1996, pp.
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From page 120... ...
Modelers are trying to predict waste form and contaminant behavior at DOE sites, including some of the most complicated and as yet poorly understood types of critical zone hydrogeologic systems, including vadose zones, regions of groundwater-surface-water interactions (including the poorly understood hyperheic zone, which is the geologic material immediately surrounding and underlying rivers and streams) , arid regions, and fractured flow regimes.
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From page 121... ...
They found that different conceptual models, matching the site data, produced different predictions attributed to underdetermined parameters and changing boundary conditions. These are just a few examples of the challenge presented in modeling hydrogeologic systems, but they are representative of the types of limitations that one should expect of a risk assessment of a hydrogeologic system.
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From page 122... ...
Boundary conditions also change over time and space, for example, along the groundwater flow path. Conceptual model uncertainty is related to whether the relevant processes have been included in the models.
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From page 123... ...
By treating the results as if they have quantitative significance, one can mislead decision makers into concentrating on numerical comparisons rather than on evaluation of the adequacy of the strategy for the safe disposal of a particular type of radioactive waste. Despite these enumerated limitations, risk assessment remains a powerful tool in organizing our understanding of the behavior of a physical and behavioral system.
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From page 124... ...
found that "[a] lmost unanimously, environmentalists resent the technocratic, exclusionary nature of risk assessments that undermine democratic participation in local environmental decisions." The risk analysis is seen as a political tool that uses science as a rationalization for decisions that have already been made.
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From page 125... ...
. Some readers will respond that the DOE process already involves stakeholders, uses risk assessment effectively, and reaches credible decisions through environmental impact statements under the National Environmental Policy Act (NEPA)
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From page 126... ...
The RBES project is an outgrowth of the DOE Office of Environmental Management (EM) Top-to-Bottom Review (DOE, 2002d)
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From page 127... ...
The meeting was held on October 6 and 7, 2004. Many at the meeting said that the RBES project had undermined trust between DOE and the other parties, and DOE representatives acknowledged errors made in implementing the policy.
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, but often this is not the case. It is therefore to be expected that public officials will look to science in the hope that it will give a clear direction for hard choices.
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From page 129... ...
The Yucca Mountain problem is being addressed by use of a complex integrated performance assessment model, but according to a white paper of the Board on Radioactive Waste Management, this complexity is viewed as virtually incomprehensible to nonspecialists (NRC, 1999) .6 6 "There are many indications that publics neither understand nor trust the expert community on radioactive waste issues.
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From page 130... ...
DOE has asked other groups to examine the environmental management problem and those groups have come up with similar recommendations. In spite of these multiple recommendations and the apparent openness of persons high within the DOE management structure, and in spite of this committee's attempts to find examples of a risk-based or riskinformed decision process at work, it appears that, with rare exception, the process of risk assessment is not being utilized effectively by the nation.
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From page 131... ...
Urgency and secrecy were also fundamental to the early days of DOE. The urgency led to unprecedented steps to achieve the fundamental mission with little importance attached to environmental considerations, although considerable attention was
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From page 132... ...
This concern led to the establishment at DOE of an Office of Environmental Management and, at each DOE site still run by M&O contractors, of a new organization devoted to environmental management or cleanup. At many of the remaining DOE sites, this environmental management organization was about the same size and had about the same budget as the former production organizations.
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From page 133... ...
There have been several attempts by Congress and high-level DOE management personnel over the last several years to insert such discipline at DOE sites; these activities are discussed in Appendix B Such activities have not been particularly successful and may have been resisted by a variety of ad hoc consortia at the various sites.
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From page 134... ...
and the incentive to persons at local sites to ensure a large and sustained influx of funds. This is a fundamental institutional barrier to the use of a risk-based approach to environmental management at DOE sites.
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From page 135... ...
In summary, the institutional barriers to the implementation of a riskbased approach to cleanup at DOE sites have been demonstrated to be effective and deeply entrenched. Although Congress has repeatedly criticized the DOE process, members of Congress representing the individual sites have sometimes contributed to the problem by the long-established method of introducing special legislation in favor of a particular site.
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From page 136... ...
DOE and its contractors have performed technically complex risk assessments, and in many cases have performed risk assessments as part of regulatory processes that lead to cleanup decisions with stakeholder input. Yet the cases examined by the committee do not meet the needs identified and described in this report for the following reasons.
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From page 137... ...
Further, many of the risk assessments examined by the committee were addressing smaller although significant problems, and so may not have warranted the effort recommended in this report. Also, the risk assessments were not necessarily aimed to fill the role described in this report.
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From page 138... ...
138 RISK AND DECISIONS ABOUT TRU AND HLW thoritative on the issues it addresses and independent so as to be unbiased and free of conflicts of interest. Before implementing this recommendation, it would be useful to consider the extensive experience of a variety of federal agencies with outside advisory committees, including the committees' roles and effectiveness.
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