Rethinking High-Level Radioactive Waste Disposal A Position Statement of the Board on Radioactive Waste Management (1990) / Chapter Skim
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Pages 13-34
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From page 13... ...
This is, in principle, the domain of performance assessment, which draws together the different portions of the technical analysis so that one can see which parts of the waste confinement system may pose environmental hazards during or after the time when the repository receives waste. Performance assessment of a repository system is necessarily a task for computer modeling.
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From page 14... ...
This was recognized by the High-Level Radioactive Waste Disposal Subcommittee of EPA's Science Advisory Board in their January 1984 report reviewing EPA Draft Standard 40 CFR 191. That subcommittee concluded there was insufficient basis for agreeing with the EPA staff that the proposed release criterion with its probabilistic corollary can be demonstrated to have been met with reasonable assurance, and that this could be argued definitively in a legal setting.
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From page 15... ...
Others are based on explicit or implicit assumptions that cannot be plausibly proved or disproved for example, the consequences of climatic changes that could increase rainfall and groundwater flows at a repository site. The data and methodologies for modeling of repository isolation performance are still under development.
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From page 16... ...
In order to encourage rigorous technical analysis, it should be required that the findings of this review group include a statement of the technical evidence and reasoning behind the conclusions, as is done now by the State of New Mexico's Environmental Evaluation Group for the Waste Isolation Pilot Plant. Given the highly polarized reactions to radioactive waste disposal, it is reasonable to anticipate criticisms and challenges to the technical competence and integrity of the program and its participants.
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From page 17... ...
These concerns have been addressed through a regulatory review process that is carefully designed to reveal errors, optimistic assumptions, and omissions; but the perceived credibility of that process can be bolstered if state and local groups and individuals have an opportunity to participate, not only in the formal review process but also through informal working relationships with project staff. Those involved in HEW management must also avoid the trap of promising to reduce uncertainties to levels that are unattainable.
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From page 18... ...
The EPA regulation requiring evidence that radioactive waste releases will be limited for 10,000 years and more is an illustration of such a concern for the distant future. · Locus.
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From page 19... ...
Many environmental groups, on the other hand, view radioactive waste as a special threat to people and the environment; they also favor permanent disposal in order to fulfill this generation's responsibility, and view interim storage as an unfair "legacy" to future generations. Some proponents of interim storage, however, argue that this generation should not make decisions that would be costly to correct in the
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From page 20... ...
The fundamental safety issue is the determination of a fair evidential process and standard of proof for showing that the repository is acceptably safe for the thousands of years over which the waste will remain dangerously radioactive. The United States has adopted a set of licensing criteria (e.g., groundwater flow time, package lifetime, waste release limits, and so on)
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From page 21... ...
An evidential dispute concerns the potential "stigma effect," including lost jobs and lost tax revenues, due to nuclear waste; the social science methodologies for assessing this effect are still controversial. Another issue concerns the use of incentives and compensation: in the 1987 NWPA amendments, Congress authorized special payments for the host state, provided it forgoes its right to object.
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Models are not well suited to describe the risk and uncertainties to lay audiences, however. Natural analogues, if they can be found, are far more useful for this purpose (see below)
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From page 23... ...
In Region 4 there is not even a sound understanding of the basic mechanisms and interactions. Appropriate Uses for Geophysical Models In the Board's judgment, a scientifically sound objective of geophysical modeling is learning, over time, how to achieve the long-term isolation of radioactive waste.
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From page 24... ...
It is illusory to expect accurate quantitative estimates of radionuclide releases from them. Sources of Uncertainty in Geophysical Models Performance assessments—estimates of the repository's ability to isolate HEW are based on current computer simulations and parameters derived from laboratory and field measurements.
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From page 25... ...
The data may be inadequate because aquifer heterogeneities occur on a scale smaller than can be defined on the basis of available data, time-dependent variables are monitored too infrequently, and measurement errors exist.10 To carry out these [repository flow] calculations, hydrogeologists are applying geostatistical models and stochastic simulation methods originally developed to assess piezometric response in near-surface unconsolidated aquifers over limited spatial distances and short time frames with relatively abundant data.
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From page 26... ...
Nor do the regulations require itEPA requires only a "reasonable assurance." The problem is that in a case without clear precedents, it is unclear what is "reasonable." The Board's point is that unsound use of technical information is not a proper substitute for the political reasoning that, in a democratic society, must in the end win consent for taking reasonable steps to advance public health and safety. In light of the limitations of technical knowledge, the Board concludes that it makes sense to conduct the assessments through an iterative process, in which the assessment provides direction to those characterizing a repository site and developing the repository engineering features.
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From page 27... ...
The alternative management strategy described in the following section would make substantial use of natural analogues, such as undisturbed natural de
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From page 28... ...
That misapplication prompts this Board to outline an alternative management strategy. The next section describes an alternative management approach that employs natural analogues and professional judgment in a program design that uses science appropriately in the search for a safe disposal system.
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From page 29... ...
The current predetermined process, in which every step is mandated in detail as in the more than 6,000-page "Site Characterization Plan,"is is inappropriate. The current policy calls for a sequential process in which EPA and the USNRC first establish the criteria for safe disposal, and then DOE describes in detail what steps will be taken to move through site characterization, licensing, and operation of the facility.
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From page 30... ...
Based on the model and geologic studies of the site, the construction of the repository is specified in detail and then carried out under an aggressive quality assurance program, which is designed to withstand regulatory review and legal challenge. Within these requirements it is the geological setting that ensures isolation, not the engineered characteristics of the system; closure aims for complete entombment and discourages subsequent remediation.
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From page 31... ...
This approach continually integrates new data into the expert judgments of geologists and engineers. It makes heavy use of natural analogues, such as undisturbed natural deposits of radioactive elements and groundwater systems, in order to illuminate the behavior of the geologic environment.
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From page 32... ...
By contrast, the EPA standards and USNBC regulations define requirements that, if met, form the basis for the presumption that the facility is "safe." Given the unhappy history of radioactive waste disposal in the United States, however, one very real and likely alternative is that nothing at all will be done. In judging disposal options, therefore, one should also adopt inaction or some other likely scenario as a default option, so that comparisons can be made and progress consistently assessed over time.
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From page 33... ...
The underlying concept of the present, anticipatory U.S. management strategy is "Get it right the first time." One result is a 6,300-page "Site Characterization Plan" for Yucca Mountain.
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From page 34... ...
This is no reason to arbitrarily abandon the release limits it is the more detailed requirements that may need to be reconsidered, since they ultimately affect the release limits and the imputed dose. However, one should not take EPA's release standards or the USNRC's detailed licensing requirements as immutable constraints.
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