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Tank Waste Retrieval, Processing, and On-Site Disposal at Three Department of Energy Sites: Final Report I Introduction In the Ronald Reagan National Defense Authorization Act (NDAA) of 2005 (Section 3146 of Public Law 108-375), Congress directed the Department of Energy (DOE) to request a study from the National Academies1 evaluating DOE’s plans to manage radioactive waste streams from reprocessed spent fuel that exceed the concentration limits for Class C low-level waste as set out in Section 61.55 of Title 10, Code of Federal Regulations;2,3 DOE plans to dispose of on the sites specified below rather than in a repository for spent nuclear fuel and high-level waste; and are stored in tanks at the Savannah River Site, South Carolina; Idaho National Engineering and Environmental Laboratory, Idaho; and the Hanford Reservation, Washington. Congress asked the National Academies to assess the following: DOE’s knowledge of the physical, chemical, and radiological characteristics of the waste in the tanks; Actions that DOE should consider to ensure that management plans comply with the performance objectives for land disposal facilities; 4 DOE’s monitoring plans to verify compliance with the aforementioned performance objectives; Existing technology alternatives for waste management; Technology gaps for waste retrieval and management; and Any other matters that the committee considers appropriate and directly related to the subject matter of the study. Task element (6) was reinforced by Representative John Spratt (5th District of South Carolina) and House Armed Services Committee staff, who presented the charge to the committee at its first meeting in March 2005 (see Appendix D). The congressman and staffers asked the committee to interpret the charge broadly to include any relevant matters of importance, with emphasis on any portion of the tank waste that would be disposed at the sites.5 Congress asked for an interim report on the Savannah River Site within six months and a final report on all of the sites within twelve months from the beginning of the study (January 2005). The interim report was issued in August 2005 (NRC, 2005a). The summary6 of that report is reproduced in Appendix E along with a section based on developments since the interim report and 1 The operating arm of the National Academies, the National Research Council, appointed a committee to undertake this study under the auspices of the Nuclear and Radiation Studies Board. Biographical sketches of the committee members can be found in Appendix A. 2 Through Part 61 of Title 10, Code of Federal Regulations (10 CFR 61) titled “Licensing Requirements for Land Disposal of Radioactive Waste,” the U.S. Nuclear Regulatory Commission regulates near-surface disposal of commercial low-level waste. Subpart 10 CFR 61.55 classifies low-level radioactive waste as Class A, B, or C, according to the concentrations of key radionuclides in the waste. Class C waste must meet more rigorous waste form requirements to ensure stability and requires additional measures at the disposal facility to protect against inadvertent intrusion. The regulation states that low-level waste that exceeds Class C limits is not generally suitable for near-surface disposal. 3 For the purpose of this study, the committee interprets the concentration criterion to apply to the waste streams stored in tanks prior to waste processing or immobilization. 4 The performance objectives of land disposal facilities for radioactive waste are defined in 10 CFR 61 Subpart C: (1) protect the general public from environmental releases and make releases as low as reasonably achievable, (2) protect individuals from inadvertent intrusion, (3) protect individuals during operations, and (4) provide stability of the site after closure (see Appendix C). 5 Specifically, Representative Spratt said “I thought it imperative that the scientific experts we were calling upon not be narrowly scoped by Congress, but rather have the authority and the latitude to look into matters unforeseen or unknown by Congress that may have a bearing on the subject.” 6 The committee’s interim report is available online at http://www.nap.edu/catalog/11415.html.
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Tank Waste Retrieval, Processing, and On-Site Disposal at Three Department of Energy Sites: Final Report feedback that DOE provided to the committee. This report is the final report addressing the statement of task in full. The committee worked with DOE, the South Carolina Department of Health and Environmental Control (DHEC), the Idaho Department of Environmental Quality, the Washington State Department of Ecology, the Oregon Department of Energy, the U.S. Environmental Protection Agency (EPA) Region 10, the U.S. Nuclear Regulatory Commission (USNRC), Native American tribal nations, DOE’s contractors, and others to obtain the information needed for the study. To this end, the committee obtained a large number of documents and held five public meetings to obtain information from experts and interested members of the public. DOE staff and contractors were responsive to the committee’s requests; however, some data and analyses were not available to the committee (not yet collected, not yet calculated, or not yet made public7), and some plans had not yet been formulated or finalized by the time this report entered the National Research Council’s report review process in late January 2006. Therefore, because the reports were not available for most of the tanks, the committee could not evaluate DOE’s intentions for complying with the performance objectives of 10 CFR 61, as required in Section 3116 of the 2005 NDAA. Section 3116, which is closely related to Section 3146 requesting this study, explicitly enables DOE to determine that some tank waste is from reprocessing of spent fuel is not high-level waste and can be disposed of on-site at the Savannah River Site and the Idaho National Laboratory, provided the requirements in that section are met.8 Section 3116 provides new waste determination criteria at these two sites but not at the Hanford Site, where DOE Order 435.1 is still in effect (albeit under the threat of litigation, see Chapter VIII).9 In this final report the committee evaluates and recommends actions that it believes could Reduce the quantity of radioactive material left onsite; Increase DOE’s understanding of other factors that could reduce dose and risk—namely, the long-term performance of waste forms and other barriers to the release of radionuclides to the environment; Improve DOE’s analyses of the choices it must make as it moves to retrieve reprocessing wastes from the tanks at the Savannah River Site, Hanford, and Idaho National Laboratory and dispose of them under the provisions of Section 3116 and Order 435.1; Improve the likelihood of processing and immobilizing these wastes in an efficient manner; and Improve DOE’s decision making through a risk-informed process. The committee judges that these actions will increase DOE’s ability to comply with the performance objectives in 10 CFR 61 and other applicable regulations, and will help DOE fulfill its requirement to take actions to make releases of radioactivity to the environment as low as reasonably achievable (ALARA), with economic and social considerations taken into account. The material in this report builds on the interim report; the committee reviewed new material from the Savannah River Site and held meetings at the Idaho National Laboratory and the Hanford Site in Washington, which broadened the committee’s perspective. OBJECTIVES FOR THE TANK WASTES The committee believes that as a starting point for analyzing options, developing plans, and making waste management decisions, it is useful to examine the life cycle of the wastes, identifying both their current conditions and the desired objectives, or “end states.”10 The choices and decisions that represent different paths from the current condition to the desired end states can then be delineated. In this section, the committee examines what the ideal objectives would be for the tank wastes and what real-world obstacles make those objectives difficult to achieve. Ideal Objectives for the Tank Wastes In an ideal world—that is, if waste retrieval and processing facilities worked perfectly and at an acceptable cost— the objectives would be the following: 7 Under the Federal Advisory Committee Act Amendments of 1997 (Public Law 105-153), any document provided to the committee from outside the National Academies must be made available to the public, unless the document is exempt from disclosure under the Freedom of Information Act (Public Law 89-554) and its amendments. As a result, DOE and others could not provide any document that was undergoing security review, internal scientific review, or legal and policy review and was therefore not ready for public release. The information-gathering phase for the interim report lasted from March through October 2005. Some of the information that the committee had requested was not available because it did not exist, was still being calculated, or was under review. 8 Before this law was signed, the full legal definition of high-level radioactive waste was waste that is “(A) the highly radioactive waste material resulting from the reprocessing of spent nuclear fuel, including liquid waste produced directly in reprocessing and any solid material derived from such liquid waste that contains fission products in sufficient concentrations; and (B) other highly radioactive material that the [Nuclear Regulatory] Commission, consistent with existing law, determines by rule to require permanent isolation” (U.S. Code, Title 42, Chapter 108, Nuclear Waste Policy, Section 10101). There is no particular concentration of radioactivity or dose limit associated with this definition. 9 Order 435.1 is an internal DOE order governing the management of radioactive waste at DOE sites. Order 435.1 includes waste determination criteria for different types of waste, including high-level waste. 10 A previous National Research Council report addressed end states for DOE’s Environmental Management sites with an application to Hanford tank waste (NRC, 1999a).
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Tank Waste Retrieval, Processing, and On-Site Disposal at Three Department of Energy Sites: Final Report Remove tank waste. The first priority for most, if not all, of the interested parties is to retrieve the waste from the tanks,11 particularly tanks that lack full secondary containment. If all of the waste could be retrieved, tank closure would be a minor concern because there would be no residual radiological hazards. No real waste retrieval system, however, will retrieve all of the waste. It is also impractical to exhume the tanks and dispose of them off-site.12 Separate the radioactive constituents from the salt solutions and bulk chemicals from the sludge. Separations are carried out primarily to reduce the volume of high-activity waste that must be immobilized, stored, and ultimately shipped to a deep geologic repository for disposal. The radionuclides constitute only a small portion of the waste volume. However, in any real separation system, complete separation of the radioactive components is not possible, which results in a low-activity waste that contains a small fraction of the radionuclides but most of the chemicals in the original tank waste. The low-activity waste would be disposed in a manner appropriate for the lower hazard it poses. Immobilize radioactive waste for disposal. The more hazardous radioactive wastes must be immobilized in a manner suitable for acceptance in a deep geologic repository (for high-level waste or transuranic waste) and the less hazardous bulk wastes must be immobilized in a form suitable for land disposal in a manner that prevents unacceptable accidental direct exposures and inhibits leaching of contaminants. The reality is that there is no perfect immobilization matrix for waste; some leaching with time is inevitable. Minimize operational hazards. The ideal objective is to eliminate operational hazards. However, some hazards always remain due to the impracticality of completely eliminating unexpected conditions, accidents, and human error. Operational hazards apply mainly to workers. Worker safety is the top priority in the near term before radionuclides and hazardous chemicals move into the accessible environment. There are also operational hazards to the public, for example, during waste transportation from the sites to a repository. Regulations require DOE to keep exposures to the public and workers as low as reasonably achievable, with economic and social considerations taken into account. Minimize residual hazards to reduce long-term maintenance. The ideal objective, again, is to eliminate the hazard of waste staying on-site, whether immobilized waste residues in the tanks (or even the tank structure, piping, and other internals) or immobilized low-activity waste. In this case, the wastes would be left in a condition that would not require institutional controls or long-term monitoring and maintenance to prevent unacceptable exposure of workers, the public, and the environment. Because it is impossible to clean the tanks perfectly, completely separate the highly hazardous radionuclides, and totally immobilize the waste, there will always be some residual hazard left on-site and therefore long-term maintenance is likely to be needed. Real-World Challenges: Difficulties in Achieving Ideal Objectives While DOE and others may strive toward these ideal outcomes, reality makes it quite difficult to achieve them, as discussed above. Examination of the disposition options, including technological capabilities, relative risks, costs, and other trade-offs, is necessary to select an appropriate plan of action. Chapter II provides background information that illustrates the challenges and difficulties at each site. Key aspects of the difficulties are examined in later chapters, and recommended strategies for addressing those challenges are offered. 11 Throughout this report, “tank waste removal” refers to removal of waste from the tank and secondary containment system, if applicable. 12 Exhuming and disposing these extremely large and contaminated waste tanks off-site would pose a tenfold increase in risks to workers, according to DOE estimates. DOE’s former assistant secretary for environmental management, Jesse Roberson, estimated in 2004 that “it would cost as much as $50 billion more over the life cycle of the department’s cleanup program and extend that life cycle by decades to have to process all of our tank waste as high-level waste for disposal in a geologic repository, including exhuming the tanks themselves, cutting them up and packaging them for disposal” (Roberson, 2004).
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