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8 Conclusions The overarching theme that guided the committee’s deliberations throughout this study is that scientific research begun now can inform the Department of Energy’s (DOE’s) future decisions for disposition of surplus nuclear materials. DOE should avoid decisions today that foreclose future options. Basic physical and chemical principles guarantee that there will be no simple, shortcut ways to replace the currently available quantities of nuclear materials that resulted from 50 years of intense effort in the United States’ massive nuclear complex during the Cold War. The large-inventory nuclear materials dealt with in this report (plutonium, spent nuclear fuels, depleted uranium, cesium-137 and strontium-90 capsules, and higher actinides) have only been available for a few decades. The next few decades may bring unforeseen beneficial uses so that these materials are recognized as valuable and irreplaceable resources. The committee concluded that the Environmental Management Science Program (EMSP) and the Office of Science have a unique opportunity to provide leadership and, by partnering with other DOE offices and private industry, financial resources to ensure that the inventory is stabilized for safe, economical, long-term storage; maintain the intellectual and facility infrastructure for world-class research and development activities with the inventoried materials; and seek beneficial uses for these materials. Research Priorities The EMSP’s congressional charter calls for long-term, path-breaking research. In addition, opportunities for research that provides a high
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potential payoff in addressing urgent, near-term needs may arise. As a practical matter, the EMSP may well encounter a range of research opportunities that span short- and long-term needs. In addition, EMSP projects may well include a technology component necessary for transitioning basic research to application (DOE, 2000a). The research recommendations in Chapters 3-7 suggest that the greatest opportunities for research that might provide shorter-term (1-5 year) payoffs are generally in the area of stabilizing the inventory for storage. Specific examples include: Plutonium: stabilize for up to 50 years of storage according to the DOE 3013 Standard. DOE spent nuclear fuel: arrest cladding degradation and prepare for several decades of storage before eventual disposal in a geological repository. Cs-137 and Sr-90 capsules: understand fundamental mechanisms that lead to swelling and potential breaching of containment. Depleted uranium: provide new methods to ensure safe removal of DUF6 from deteriorated containers to support DOE’s plan for converting the DUF6 to a stable oxide. Higher actinides: develop stable forms to allow their removal from closure sites, shipment, and storage at sites with a continuing nuclear materials mission. Begun now, longer-term research would feed a continuously growing body of scientific information to support decision making and have the potential of eventually providing scientific breakthroughs. Longer-term research should be directed toward beneficial new uses for DOE’s nuclear materials or their disposal. Examples include: Plutonium: maximize the portion of the scrap inventory that can be converted to MOX fuel. DOE spent nuclear fuel: ensure that it meets waste acceptance criteria for disposal with a minimum amount of treatment. Cs-137 and Sr-90: develop stable, non-dispersible matrices for storage to decay (several hundred years) or disposal. Depleted uranium and heavy actinides: strive to develop beneficial uses along with further understanding health effects that might suggest or preclude some uses; provide a scientific basis for disposing the DU oxide and heavy actinides. Crosscutting Opportunities This report is the last in a series of five National Academies’ studies requested by the EMSP to assist in providing an agenda for research to
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support and enhance DOE’s site cleanup program (NRC, 2000, 2001a, 2001b, 2002). The previous reports dealt with environmental contamination and waste issues. Most of the excess nuclear materials that are the subject of this report have not been declared as waste, and according to its statement of task the committee emphasized research directed toward preserving and reusing the materials. Nevertheless, there is a broad consistency among the recommendations in all five studies. Three areas stand out as offering opportunities for the EMSP to support scientific research that crosscuts most of DOE’s cleanup challenges. For DOE’s excess nuclear materials, wastes, and contaminated media crosscutting topics for research include: characterization of their fundamental chemical, physical, and biological properties; treatment to ensure their near- and long-term stability, including understanding the fundamental parameters that affect stability; and assessment of their actual health or environmental risks. By focusing its limited funds in these crosscutting areas, and leveraging its limited funding by cooperative research with other DOE offices or the private sector, the EMSP is most likely to achieve the scientific breakthroughs intended by its congressional charter.
Representative terms from entire chapter: