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Introduction, Background, and Task
The Department of Energy’s (DOE’s) Environmental Management Science Program (EMSP) was established by the 104th Congress1 to bring the nation’s basic science infrastructure to bear on the massive environmental cleanup effort under way in the DOE complex. The objective of the EMSP is to develop and fund a targeted, long-term research program that will result in transformational or breakthrough approaches for solving the department’s environmental problems. The goal (DOE, 2000a, pp. 1-2) is to support research that will
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Lead to significantly lower cleanup costs and reduced risks to workers, the public, and the environment over the long term.
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Bridge the gap between broad fundamental research that has wide-ranging applicability . . . and needs-driven applied technology.
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Serve as a stimulus for focusing the nation’s science infrastructure on critical national environmental management problems.
To help meet these goals, the EMSP provides 3-year competitive awards to investigators in industry, national laboratories, and universities to undertake research on problems relevant to DOE cleanup efforts. From its inception in 1996, the EMSP has provided $327 million in funding for 399 research projects.
This study, addressing DOE’s excess nuclear materials and spent nuclear fuels, is the fifth study undertaken by the National Academies’ National Research Council (NRC) to assist DOE in developing a research agenda for the EMSP.2 The previous four reports (NRC, 2000, 2001a, 2001b, 2002) gave advice for research in subsurface contamination,
high-level waste, facility deactivation and decontamination, and transuranic and mixed wastes. DOE has used these studies in developing calls for research proposals and for evaluating proposals submitted.
After its establishment by Congress and through most of the course of this study, the EMSP was managed by a partnership between the DOE Office of Environmental Management (EM), which has primary responsibility for the cleanup mission, and the DOE Office of Science, which manages basic research programs. The advice provided by the NRC studies, as well as the EMSP’s calls for proposals, reflected EM’s organization of its science and technology development activities into five “focus areas,” which are the topical areas of the NRC studies mentioned above— subsurface contamination, high-level waste, facility deactivation and decommissioning, transuranic and mixed wastes, and nuclear materials.
During the course of this study the EMSP was in transition from EM to the DOE Office of Science, Environmental Remediation Sciences Division (ERSD).3 The committee did not attempt to assess or comment on this transition, but rather focused its attention on research needs and opportunities for DOE’s excess nuclear materials. However, the committee joins the four previous NRC committees in noting that the program’s approximately $30 million annual budget allocation can support only a small fraction of the research agenda that is needed to address the EMSP’s objectives.
With its new home in the Office of Science, the EMSP has a better opportunity to coordinate its research programs with other DOE offices (e.g., Office of Civilian Radioactive Waste Management, Office of Nuclear Energy, Science and Technology) and non-DOE organizations (e.g., Department of Defense, National Science Foundation) that are supporting similar research. Such cooperation might be along disciplinary rather than programmatic lines. Maintaining relevance to EM problems may be more difficult after the transition. Since July 2000, ERSD has been developing a strategic plan to better integrate the EMSP with other environmental research and development programs (Patrinos, 2002). The plan had not been finalized at the time this report was completed.
Statement of Task
The statement of task for this study charged the committee to provide recommendations for a science research program for treatment, storage, and recycle, reuse, or disposal4 of nuclear materials, including
SIDEBAR 1.1 STATEMENT OF TASK The objective of this study is to provide recommendations to the Environmental Management Science Program on a research agenda to improve the scientific basis for treatment, storage, and recycle/reuse/disposal of spent nuclear fuel and nuclear materials (including depleted uranium) that are currently being managed by DOE or will be generated in the future as part of DOE’s cleanup program. The study will accomplish the following:
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depleted uranium and spent nuclear fuels, that are currently being managed by DOE or will be produced as part of DOE’s site cleanup program (see Sidebar 1.1).
To address the statement of task, the committee directed its attention to the following five groups of materials that it believes present the most difficult challenges and provide the greatest opportunities for EMSP research to significantly improve DOE’s ability to manage its excess nuclear materials and spent nuclear fuels:
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Plutonium-239. The inventory of Pu-bearing solids that is considered DOE legacy material encompasses approximately 100 metric tons, about half of which has been declared as excess. Much of the excess includes scraps and residues that have uncertain disposition routes. The material presents significant technical challenges, and potential health and security risks.
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Spent nuclear fuel. DOE manages a wide variety of fuel types, which total approximately 2,500 metric tons. Many fuels are corroding, and their processing or disposal is many years away. They present significant technical challenges and potential health risks. Highly enriched uranium fuels may present security risks.
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Cesium-137 and strontium-90 capsules. Approximately 2,000 capsules stored at the Hanford, Washington, site contain a total of 67 million curies of radioactivity within a volume of only about 5 cubic meters. These capsules represent almost 40 per-
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cent of the radioactivity at the Hanford site and have been described as the most intense single source of radiation in the United States, except inside the core of an operating nuclear reactor. Their disposition presents significant technical challenges and potential health risks.
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Depleted uranium. A residue from uranium enrichment operations, DOE’s inventory includes over 700,000 metric tons of uranium hexafluoride (UF6), which can produce toxic hydrogen fluoride and uranyl compounds upon reacting with moisture and air. Most is stored at three sites in 14-ton carbon steel canisters, many of which are badly corroded and some of which have leaked. DOE intends to convert the UF6 to a more stable oxide. Disposition plans for the oxide have not yet been determined.
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Higher actinides. Including neptunium-237, americium-243, and curium-244, these are materials that can no longer be produced in the United States in the kilogram quantities that now exist. Continued storage is expensive and presents potential health risks; discarding them may prove to be an irrevocable loss of a unique asset.
Some excess nuclear materials in the DOE inventory (e.g., U-233, thorium) were not considered by the committee because they appear to present fewer challenges in terms of risk, volume, cost, or unique research opportunities as those in the five groups selected (see DOE, 2000c). Among those selected, the committee sought to be comprehensive in identifying scientifically valid and relevant research, realizing that only a fraction of this research can be funded. The general research recommendations were developed through a consensus process that considered input to the committee, site needs, the existence of critical knowledge gaps, the potential for future cost and schedule savings, and the possibility of achieving scientific breakthroughs.
Chapter 2 of this report describes the origin, disposition options, and challenges of nuclear materials in the DOE complex. The chapter also frames the committee’s views on how new knowledge gained through EMSP research can assist DOE’s broader, long-term decisions for managing and dispositioning its excess nuclear material.
Chapters 3 though 7 address each of the five sets of materials. In each chapter, an overview describes the current status and DOE’s plans for dealing with the material. Technical gaps and challenges, as determined from the committee’s fact-finding visits to DOE sites, literature reviews, and deliberations, are presented. The committee then gives its general recommendation and describes opportunities for EMSP research to address the gaps and challenges and to enhance scientific knowledge generally.
Chapter 8 summarizes the research recommendations and suggests a broad prioritization of near-term (1-5 year) and longer-term nuclear materials research. Because this report is the last in a series of five National Academies’ reports that have suggested research agendas for the EMSP, the committee also provided a summary of research that crosscuts all five reports.
The committee held six meetings between October 2001 and September 2002 to gather information (see Appendix C). The committee’s fact finding included site visits and briefings at the Los Alamos National Laboratory (New Mexico), Oak Ridge Reservation (Tennessee), Savannah River Site (South Carolina), and the Hanford Site and Pacific Northwest National Laboratory (Washington). The committee also received briefings by DOE headquarters personnel. Especially useful were roundtable discussions among the committee and scientists from Los Alamos and Sandia National Laboratories (New Mexico), Oak Ridge, Savannah River, Hanford, and Pacific Northwest National Laboratory.