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Appendix C Interim Report 255
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257 APPENDIX C Waste Forms Technology and Performance INTERIM REPORT Committee on Waste Forms Technology and Performance Nuclear and Radiation Studies Board Division on Earth and Life Studies THE NATIONAL ACADEMIES PRESS Washington, D.C. www.nap.edu
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258 APPENDIX C THE NATIONAL ACADEMIES PRESS 500 Fifth Street, N.W. Washington, DC 20001 NOTICE: The project that is the subject of this report was approved by the Governing Board of the National Research Council, whose members are drawn from the councils of the National Academy of Sciences, the National Academy of Engineering, and the Institute of Medicine. The members of the committee responsible for the report were chosen for their special competences and with regard for appropriate balance. This study was supported by Contract No. DE-FC01-04EW07022 between the National Academy of Sciences and the U.S. Department of Energy. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of the organizations or agencies that provided support for the project. This report is available online at www.nap.edu. Copyright 2010 by the National Academy of Sciences. All rights reserved. Printed in the United States of America
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259 APPENDIX C The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. Upon the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters. Dr. Ralph J. Cicerone is president of the National Academy of Sciences. The National Academy of Engineering was established in 1964, under the charter of the National Academy of Sciences, as a parallel organization of outstanding engineers. It is autonomous in its administration and in the selection of its members, sharing with the National Academy of Sciences the responsibility for advising the federal government. The National Academy of Engineering also sponsors engineering programs aimed at meeting national needs, encourages education and research, and recognizes the superior achievements of engineers. Dr. Charles M. Vest is president of the National Academy of Engineering. The Institute of Medicine was established in 1970 by the National Academy of Sciences to secure the services of eminent members of appropriate professions in the examination of policy matters pertaining to the health of the public. The Institute acts under the responsibility given to the National Academy of Sciences by its congressional charter to be an adviser to the federal government and, upon its own initiative, to identify issues of medical care, research, and education. Dr. Harvey V. Fineberg is president of the Institute of Medicine. The National Research Council was organized by the National Academy of Sciences in 1916 to associate the broad community of science and technology with the Academy’s purposes of furthering knowledge and advising the federal government. Functioning in accordance with general policies determined by the Academy, the Council has become the principal operating agency of both the National Academy of Sciences and the National Academy of Engineering in providing services to the government, the public, and the scientific and engineering communities. The Council is administered jointly by both Academies and the Institute of Medicine. Dr. Ralph J. Cicerone and Dr. Charles M. Vest are chair and vice chair, respectively, of the National Research Council. www.national-academies.org
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260 APPENDIX C Nuclear and Radiation Studies Board 500 Fifth Street, NW Washington, DC 20001 Phone: 202 334-3066 Fax: 202 334-3077 www.nationalacademies.org June 15, 2010 Yvette Collazo Deputy Assistant Secretary for Technology Innovation and Development Office of Environmental Management U.S. Department of Energy Washington, DC 20585 Subject: Interim Report on Waste Form Technology and Performance Dear Ms. Collazo: The Committee on Waste Forms Technology and Performance (Attachment B) was appointed by the National Research Council in May 2009 to examine requirements for waste form (Box 1) technology and performance in the context of the disposal system in which the waste will be emplaced. The complete statement of task for this study is given in Box 2. The Department of Energy, Office of Environmental Management (DOE-EM) requested this interim report to provide timely information for fiscal year 2011 technology development planning. The committee has focused this interim report on opportunities associated with selected aspects of the last three bullets of its statement of task (Box 2). These tasks are: The state-of-the-art tests and models of waste forms used to predict their performance for time periods appropriate to their disposal system. 1 Potential modifications of waste form production methods that may lead to more efficient production of waste forms that meet their performance requirements. Potential new waste forms that may offer enhanced performance or lead to more efficient production. The committee judges that the opportunities identified in this report are sufficiently mature to justify consideration by DOE-EM as it plans its fiscal year 2011 technology development program. 1 The focus of this interim report is primarily on tests and models for assessing waste form durability (see Footnote 6). The final report will provide a more detailed discussion of waste form performance over time periods of concern for disposal.
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Yvette Collazo 261 June 15, 2010 APPENDIX C Page 2 Box 1: Waste Forms The International Atomic Energy Agency defines waste immobilization as the conversion of a waste into a waste form by solidification, embedding, or encapsulation. The waste form can be produced by chemical incorporation of the waste species into the structure of a suitable matrix (typically a glass or ceramic) so that the radioactive species are atomistically bound in the structure. Chemical incorporation is typical for high-level radioactive waste. Encapsulation of waste, on the other hand, is achieved by physically surrounding it in materials (typically bitumen, grout, or cement) so it is isolated and radionuclides are retained. Encapsulation is typically used for low-level or intermediate- level waste and may include some chemical incorporation. The primary role of a waste form is to immobilize radioactive and/or hazardous constituents in a stable, solid matrix for storage and eventual disposal. In a well-designed disposal system, the waste forms and disposal facility into which they are emplaced work together to sequester radioactive and hazardous constituents. The near-field environment of the disposal site and other engineered barriers, if present, establish the physical and chemical bounds within which the waste form performs its sequestering function. This promotes the maintenance of waste form integrity over extended periods, which helps to slow the release of radioactive and other hazardous constituents from the waste form and the transport of these constituents out of the disposal facility. In addressing these charges, the committee has focused primarily, but not exclusively, on high-level radioactive waste (HLW) cleanup, which is the longest schedule, highest cost, highest risk, and arguably DOE-EM’s most difficult technical cleanup challenge (see, for example, DOE, 1998, 2010a; NRC, 2001, 2006). At present, tank waste retrieval and closure are limited by schedules for treating and immobilizing HLW in the Defense Waste Processing Facility, which is currently operating at the Savannah River Site; the Waste Treatment Plant, which is under construction at the Hanford Site; and a facility to be designed and constructed at the Idaho Site. Accelerating schedules for treating and immobilizing HLW by introducing new and/or improved waste forms and processing technologies could also accelerate tank waste retrieval and closure schedules. The committee used its expert judgment to identify the opportunities described in this report. This judgment was informed through a series of briefings, site visits, and a scientific workshop. The committee received briefings on DOE’s current programs and future plans for waste processing, storage, and disposal from DOE-EM, national laboratory, and contractor staff, including information on comparable international programs. The committee visited the Hanford Site (Washington), Idaho Site, Savannah River Site (South Carolina), and their associated national laboratories (Pacific Northwest National Laboratory, Idaho National Laboratory, and Savannah River National Laboratory, respectively) to observe DOE’s waste processing and waste form production programs and to hold technical discussions with site and laboratory staff. The committee also organized a workshop to discuss scientific advances in waste form development and processing. This workshop, which was held in Washington, D.C., on November 4, 2009, featured presentations from researchers in the United States, Russia, Europe, and Australia. The workshop agenda is provided in Attachment C.
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Yvette Collazo 262 15, 2010 June APPENDIX C Page 3 Box 2: Statement of Task The National Academies will examine the requirements for waste form technology and performance in the context of the disposal system in which the waste form will be emplaced. Findings and recommendations will be developed to assist DOE in making decisions for improving current methods for processing radioactive wastes and for selecting and fabricating waste forms for disposal. The study will identify and describe: Essential characteristics of waste forms that will govern their performance within relevant disposal systems. This study will focus on disposal systems associated with high-cost waste streams such as high-level tank waste and calcine but include some consideration of low-level and transuranic waste disposal. Scientific, technical, regulatory, and legal factors that underpin requirements for waste form performance. The state-of-the-art tests and models of waste forms used to predict their performance for time periods appropriate to their disposal system. Potential modifications of waste form production methods that may lead to more efficient production of waste forms that meet their performance requirements. Potential new waste forms that may offer enhanced performance or lead to more efficient production. The committee will not make recommendations on applications of particular production methods or waste forms to specific EM waste streams. A major focus of the DOE-EM cleanup program is on retrieving legacy wastes resulting from nuclear weapons production and testing and processing them into waste forms suitable for disposal in onsite or offsite facilities. Some waste requires minimal processing to make it suitable for disposal; for example, lightly contaminated solid waste generated during facility decommissioning may be suitable for disposal in near-surface engineered facilities with little or no processing. Other waste will require more extensive processing to make it suitable for disposal; for example, HLW, liquid wastes from facility decontamination, contaminated resins from groundwater cleanup, and radioactive sources and other nuclear materials used in civilian and defense applications may require processing to destroy organic components; to remove components that are incompatible with the processing method or final waste form or that are not acceptable for disposal; and to immobilize radioactive and other hazardous components. DOE-EM is using a variety of waste forms to immobilize these components. The committee observes that the DOE-EM cleanup program is successfully processing waste and producing waste forms at several sites. For example, DOE has completed HLW vitrification at the West Valley, New York, site. DOE is also retrieving HLW from tanks at the Savannah River Site, separating it into high-activity and
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Yvette Collazo June 15, 2010 263 APPENDIX C Page 4 low-activity waste streams, and processing these waste streams into high-activity waste glass for disposal in a future geologic repository and low-activity waste saltstone for near-surface onsite disposal. However, DOE-EM’s cleanup program is not expected to be completed for at least another four decades. Consequently, as this program continues, DOE-EM will have opportunities to incorporate emerging developments in science and technology on waste forms and waste form production technologies into its baseline approaches to increase program efficiencies, reduce lifecycle costs and risks, and advance scientific understanding of and stakeholder confidence in waste form behavior in different disposal environments. In short, scientific advances, both now and in the future, will offer the potential for better solutions to DOE-EM’s waste management challenges. It may be important for DOE-EM to maintain sufficient flexibility in its cleanup program to take advantage of these advances. Based on an analysis of the information it has gathered, the committee observes that waste form science and technology have advanced significantly over the past three decades. The committee judges that there are opportunities to apply these advances in the DOE-EM cleanup program, both now and in the future, to reduce schedules, costs, and risks. The committee offers several observations about potential opportunities in this interim report. Detailed findings and recommendations will be provided in the committee’s final report. Waste form-relevant science and technology are advancing rapidly along several fronts—for example, chemical and materials processing in industry, waste management in advanced nuclear fuel cycle programs, and management of special nuclear materials in national security applications. There have been numerous recent reports on the development of waste forms and processing technologies for advanced nuclear fuel cycles; some examples are given in Attachment D. Examples of these technologies include: Waste form materials designed for significantly higher waste loadings or for improved performance in specific disposal environments. Waste processing technologies that can handle large volumes of highly radioactive wastes or that produce highly uniform waste form products. Advanced analytical and computational techniques that can be used to understand and quantitatively model interactions between waste forms and near-field 2 environments of disposal facilities. Many of these technologies are potentially applicable to DOE-EM waste streams. However, not all are ready for full-scale implementation. This interim report and the committee’s final report provide only snapshots of these advances. To take full advantage of future scientific and technological 2 The near-field environment is generally taken to include the engineered barriers in a disposal system (e.g., waste canisters) as well as the host geologic media in contact with or near these barriers whose properties have been affected by the presence of the repository. The far-field environment is generally taken to include areas beyond the near field, including the biosphere (e.g., OECD-NEA, 2003).
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Yvette Collazo 264 15, 2010 June APPENDIX C Page 5 advances, DOE-EM will need to identify, develop where needed, and incorporate where appropriate state-of-the-art science and technology on waste forms and waste form production processes, especially for high-cost, high-risk, and/or orphan 3 waste streams. DOE-EM can become cognizant of scientific and technological advances by collaborating with appropriate governmental, scientific, and technical organizations to identify waste forms and waste form production technologies that are potentially applicable to DOE-EM waste streams. For example, collaborations can be established with other DOE offices, 4 especially the Office of Science and Office of Nuclear Energy; other government agencies (e.g., Department of Defense); scientific, academic, and industrial organizations; and especially other nations’ radioactive waste management programs. DOE-EM is operating its cleanup program under various regulatory requirements and legal agreements with states and the U.S. Environmental Protection Agency. Modifications of existing requirements or agreements might be necessary before DOE- EM could implement the technologies identified in this report. However, it is outside of the committee’s scope to consider how the use of the technologies identified in this report might impact those requirements and agreements. WASTE FORM AND PROCESSING OPPORTUNITIES The committee has identified four opportunities consistent with its statement of task (Box 2): Production of crystalline ceramic 5 waste forms using fluidized bed steam reforming Production of glass, glass composite, and crystalline ceramic waste forms using cold crucible induction melters Production of glass, glass composite, and crystalline ceramic waste forms using hot isostatic pressing Evaluation of the long-term durability of new waste form materials using experimental studies, laboratory tests, and model development 3 A waste stream is referred to as orphan when it has no clear-cut disposition pathway. The DOE- EM cleanup program has identified several orphan waste streams including, for example, actinide targets, beryllium reflectors, certain radioactive wastes produced outside of the nuclear fuel cycle, and sealed radiation sources. Many of these orphan waste streams are volumetrically small compared to the inventories of high-level waste, transuranic waste, and low-level waste that exist at DOE sites. 4 See, for example, the basic research needs reports that are listed in Attachment D. 5 A crystalline material has a well-defined, periodic-ordering of its atomic structure. Crystalline ceramic materials can consist of one or more crystalline phases. In contrast, a glass is aperiodic and lacks long-range atomic-scale ordering. Glass composite materials consist of a mixture of both glass and crystalline phases.
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Yvette Collazo June 15, 2010 265 APPENDIX C Page 6 The first three opportunities involve new applications of existing technologies to DOE-EM waste streams. These waste form production technologies are being used commercially and appear to be applicable for processing and immobilizing a range of DOE-EM waste streams, especially HLW streams. DOE-EM is already planning to apply these technologies to some of its waste streams, as discussed in the following sections. The committee concurs with DOE-EM about the applicability of these technologies and offers observations in this interim report on the wider application of these technologies in the cleanup program. The fourth opportunity involves extending the application of experiments, tests, and model development for evaluating the durability 6 of new waste form materials over time periods for concern for disposal (typically 103-106 years). This would provide DOE- EM with future flexibility to use new waste forms in its cleanup program and enhance the long-term safety of disposal. Fluidized Bed Steam Reforming Technology Fluidized Bed Steam Reforming (FBSR; see Attachment E for a brief technology description) is a robust technology for processing wastes. Its primary advantages are high throughput and ability to accommodate a wide range of feeds and additives, including feeds containing anionic sulfur and nitrogen species, halides, and organics that are incompatible with some other types of waste forms and waste form production processes. FBSR is based on fluidized bed technology, which was invented in the 19th century and found widespread use in the refining and chemical industries starting around World War II. Applications of fluidized bed technology in nuclear fuel production, fuel recovery, and waste processing date back to late 1950s and early 1960s. For example, fluidization was used for the reduction and hydrofluorination of uranium concentrates and calcination of high-level radioactive waste. Two calcination facilities were successfully operated at the Idaho National Engineering Laboratory (now Idaho National Laboratory) from 1963 to 1981 and from 1981 to 2000 to immobilize HLW. The FBSR process is already being used commercially for processing nuclear waste. A commercial facility to continuously process organic radioactive wastes at moderate temperatures in a hydrothermal steam environment was built by Studsvik in Erwin, Tennessee, in 1999. The Erwin facility uses a steam reforming technology, referred to as THermal Organic Reduction (THOR®), to pyrolyze organic resins loaded with Cs-137 and Co-60 from commercial nuclear facilities. The Erwin facility has the current capability to process a wide variety of solid and liquid streams including ion exchange resins, charcoal, graphite, sludge, oils, solvents, and cleaning solutions at radiation levels of up to 400R/hr (Mason et al., 1999). 6 Durability is a measure of the resistance of a waste form to physical and chemical alteration and the associated release of contained radioactive or hazardous constituents.
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Yvette Collazo 274 15, 2010 June APPENDIX C Page 15 Attachment A: References ASME (American Society of Mechanical Engineers). 1985. The Evolution of HIP: Commemorating the First Hot and Cold Isostatic Processing Vessels. ASME Landmarks Program. Available at http://files.asme.org/ASMEORG/Communities/History/Landmarks/5569.pdf Clarke, D.R. 1981. Preferential dissolution of an intergranular amorphous phase in a nuclear waste ceramic. J. Am. Ceram. Soc 64, C89-90. Cooper, J.A., Cousens, D.R., Hanna, J.A., Lewis, R.A., Myhra, S., Segall, R.L., Smart, R. St.C., Turner, P.S., and T.J. White, 1986. Intergranular films and pore surfaces in Synroc C: Structure, Composition, and Dissolution characteristics, J. Am. Ceram. Soc, 69(4), 347-352. DOE (U.S. Department of Energy). 1998. Accelerating Cleanup: Paths to Closure. DOE/EM-0362. Washington, D.C.: Office of Environmental Management. DOE. 2010a. Technical Evaluation of Strategies for Transforming the Tank Waste System: Tank Waste System Integrated Project Team Final Report. Washington, D.C.: U.S. Department of Energy. DOE. 2010b. Amended Record of Decision: Idaho High-Level Waste and Facilities Disposition Final Environmental Impact Statement Revised by State 12/21/09. Federal Register 75(1), 137-140. Available at http://edocket.access.gpo.gov/2010/pdf/E9-31151.pdf. Elliott, M.L. 1996. Letter report: Cold Crucible Melter Assessment. PNNL-11018. Richland, Wash.: Pacific Northwest National Laboratory. IPET [Independent Project Evaluation Team]. 2003. Technical Evaluation of Hanford HLW Vitrification Process Alternatives: Report of the Independent Project Evaluation Team. U.S. Department of Energy. Jantzen, C.M. 2004. Disposition of Tank 48H Organics by Fluidized Bed Steam Reforming (FBSR). WSRC-TR-2003-00352, Rev. 1. Aiken, S.C.: Westinghouse Savannah River Co. Jantzen, C.M. 2006. Fluidized Bed Steam Reformer (FBSR) Product: Monolith Formation and Characterization. WSRC-STI-2006-00033. Aiken, S.C.: Westinghouse Savannah River Co.. Jantzen, C.M. and M.R. Williams. 2008. Fluidized bed steam reforming (FBSR) mineralization for high organic and nitrate waste streams for the Global Nuclear Energy Partnership (GNEP), Waste Management ‘08, Paper #8314. Marshall, D.W., Soelberg, N.R., and K.M. Shaber. 2003. THORsm Bench-Scale Steam Reforming Demonstration. INEEL/EXT-03-00437. Idaho Falls: Idaho National Engineering & Environmental Laboratory. Mason, J.B., Oliver, T.W., Carson, M.P., and G.M. Hill. 1999. Studsvik Processing Facility Pyrolysis/Steam Reforming Technology for Volume and Weight Reduction and Stabilization of LLRW and Mixed Wastes, Waste Management ‘99.
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Yvette Collazo June 15, 2010 275 APPENDIX C Page 16 NRC [National Research Council]. 2001. Research Needs for High-Level Waste Stored in Tanks and Bins at U.S. Department of Energy Sites. Washington, D.C.: National Academy Press. NRC. 2006. Tank Waste Retrieval, Processing, and On-Site Disposal at Three Department of Energy Sites. Washington, D.C.: National Academy Press. OECD-NEA [Organisation for Economic Co-Operation and Development, Nuclear Energy Agency]. 2003. Engineered Barrier Systems and the Safety of Deep Geological Repositories: State-of-the-art Report. Paris, France: OECD. 76 pp. Steefel, C.I., DePaolo, D.J., and P. C. Lichtner. 2005. Reactive transport modeling: An essential tool and a new research approach for the Earth sciences. Earth and Planetary Science Letters 240, 539-558. Vernaz, E.Y., and C. Poinssot. 2008. Overview of the CEA French Research Program on Nuclear Waste. Mater. Res. Soc. Symp. Proc. 1107. Vernaz, E.Y. 2009. (editor) Nuclear Waste Conditioning. Paris, France: Commissariat à l'Énergie Atomique. Zhang Z., and M.L. Carter. 2010. An X-ray photoelectron spectroscopy investigation of highly soluble grain-boundary impurity films in hollandite. J. Am. Ceram. Soc. 93(3), 894-899.
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Yvette Collazo 276 15, 2010 June APPENDIX C Page 17 Attachment B: Committee on Waste Forms Technology and Performance MILTON LEVENSON, Chair, Bechtel International (retired), Menlo Park, California RODNEY C. EWING, Vice Chair, University of Michigan, Ann Arbor JOONHONG AHN, University of California, Berkeley MICHAEL J. APTED, INTERRA, Inc., Denver, Colorado PETER C. BURNS, University of Notre Dame, Notre Dame, Indiana MANUK COLAKYAN, Dow Chemical Company (retired), South Charleston, West Virginia JUNE FABRYKA-MARTIN, Los Alamos National Laboratory, Los Alamos, New Mexico CAROL M. JANTZEN, Savannah River National Laboratory, Aiken, South Carolina DAVID W. JOHNSON, JR, Bells Labs (retired), Bedminster, New Jersey KENNETH L. NASH, Washington State University, Pullman TINA M. NENOFF, Sandia National Laboratories, Albuquerque, New Mexico Staff KEVIN D. CROWLEY, Study Director DANIELA STRICKLIN, Study Director (Through February 12, 2010) SARAH CASE, Staff Officer TONI GREENLEAF, Administrative and Financial Associate SHAUNTEÉ WHETSTONE, Senior Program Assistant JAMES YATES, JR., Office Assistant
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Yvette Collazo June 15, 2010 277 APPENDIX C Page 18 Attachment C: Workshop Agenda Workshop on Waste Form Technology and Performance The Lecture Room The National Academy of Sciences (NAS) Building 2101 Constitution Avenue, NW, Washington, DC 20418 Wednesday, November 4, 2009 Welcome and Introduction 8:15-8:30 am Milt Levenson and Rod Ewing Session I: International Perspectives Glass and spent fuel corrosion, coupling of waste forms to the 8:30–9:00 am near field, and long-term models of performance Berndt Grambow, Laboratoire De Physique Subatomique Et Des Technologies Associees (SUBATECH), France Cementatious waste forms and barriers 9:00–9:30 am Fred Glasser, University of Aberdeen, UK Combined inert matrix fuels and related waste forms 9:30-10:00 am Claude Degueldre, Paul Sheerer Institute, Switzerland Break 10:00-10:30 am Ceramic and phosphate glass waste forms and cold crucible 10:30-11:00 pm technology Sergey Stefanovsky, SIA Radon, Russia Overview of CEA’s and French initiatives related to waste forms 11:00-11:30 pm Etienne Vernaz, Commissariat à l'Énergie Atomique, France Overview of Australia/ANSTO initiatives related to waste forms 11:30-12:00 pm Kath Smith and Bruce Begg, Australian Nuclear Science and Technology Organisation (ANSTO), Australia Lunch 12:00-1:00 pm Session II: Select Domestic Issues Computational methods applied to the design and evaluation of 1:00–1:30 am waste forms Bill Weber, Pacific Northwest National Laboratory
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Yvette Collazo 278 15, 2010 June APPENDIX C Page 19 Overview of waste forms and near-field interactions in a 1:30-2:00 pm performance assessment perspective Carl Steefel, Lawrence Berkeley National Laboratory Matching waste forms to waste processing strategies 2:00-2:30 pm Mark Peters, Argonne National Laboratory Impact of waste forms on overall repository performance 2:30-3:00 pm assessment Peter Swift, Sandia National Laboratories Break 3:00-3:15 pm Overview of the Vitreous State Laboratory and geopolymer 3:15-3:45 pm development Ian Pegg and Werner Lutze, Catholic University of America Cementitious Barriers Partnership 3:45-4:15 pm David Kosson, Vanderbilt University Industry perspectives on potential waste forms from recycling 4:15-4:45 pm Rod McCullum, Nuclear Energy Institute Panel discussion 4:45-5:15 pm All participants Adjourn 5:15 pm
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Yvette Collazo June 15, 2010 279 APPENDIX C Page 20 Attachment D: Selected Recent Reports on Science and Technology for Waste Immobilization Summary Report of the Nuclear Energy Research Initiative Workshop, April 23-25, 1998 (see the report of working group #4). Available at http://www.ne.doe.gov/pdfFiles/nerachWorkshop.pdf. Basic Research Needs for Advanced Nuclear Energy Systems, July 31- August 3, 2006 (see the panel #5 report on advanced waste forms). Available at http://www.er.doe.gov/bes/reports/files/ANES_rpt.pdf. Basic Research Needs for Geosciences: Facilitating 21st Century Energy Systems, February 21-23, 2007 (see sections related to subsurface geologic storage and modeling/simulation of geologic systems). Available at http://www.er.doe.gov/bes/reports/files/GEO_rpt.pdf. Basic Research Needs for Materials under Extreme Environments, June 11-13, 2007 (see section on nuclear energy). Available at http://www.er.doe.gov/bes/reports/files/MUEE_rpt.pdf. Global Nuclear Energy Partnership Integrated Waste Management Strategy Waste Treatment Baseline Study. GNEP-WAST-AI-RT-2007-00034. 2007 (see vol. 1 sections on processing and stabilization with different types of waste forms). Directing Matter and Energy: Five Challenges for Science and the Imagination, A Report from the Basic Energy Sciences Advisory Committee, 2007 (see chapter 7 on designing new materials). Available at http://www.er.doe.gov/bes/reports/files/GC_rpt.pdf. Advice on the Department of Energy’s Cleanup Technology Roadmap: Gaps and Bridges. 2009. National Academies Press. Available at http://www.nap.edu/openbook.php?record_id=12603&page=1.
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Yvette Collazo 280 15, 2010 June APPENDIX C Page 21 Attachment E: Fluidized Bed Steam Reforming A bed of granular material can be made to exhibit fluid-like properties by passing a liquid or gas through it. This process is referred to as fluidization, and the apparatus that supports this process is referred to as a fluidized bed. Fluidization came to age during World War II, when the urgent demand for aviation gasoline led to the development and construction of the first fluid bed catalytic cracker. In addition to gasoline production, fluidization technology is broadly used in coal gasification and combustion, mineral processing, food processing, pharmaceuticals, soil washing, manufacturing of polymers, waste treatment, and environmental remediation. Its applications include several unit operations such as drying, heating/cooling, particle coating, and chemical reactions. The Fluidized Bed Steam Reforming (FBSR) of nuclear waste is a relatively new technology, though the fluidization phenomenon and steam reforming are well established in the chemical engineering field. Steam reforming is a method for generating hydrogen by reacting fossil fuels with water. For example, for natural gas: CH4(g) + H2O(g) CO(g) + 3H2(g) If coal is used as a carbon source, it first undergoes pyrolysis or devolatilization then the char (C) reacts with steam according to the following reaction: C(s) + H2O(g) CO(g) + H2(g) The H2 is combined with O2 so that no excess H2 exists in the system at any one time. This combination is exothermic and provides energy in the form of heat for the autocatalytic operation of the FBSR. The FBSR consists of two fluidized beds. The first one operates in a reducing environment and its function is to evaporate the liquid nuclear waste stream; destroy organics; reduce nitrates, nitrites, and nitric acid to nitrogen gas; and form a stable solid waste product. The first stage fluidized bed of the FBSR process is referred to as the Denitration and Mineralization Reformer, or DMR. The DMR uses superheated steam as the fluidizing media. The bed material consists of granular solid additives and co- reactant(s), such as carbon, clay, silica, and/or catalysts. Liquid waste is directly fed to the fluidized bed after minor pre-treatment (e.g., to concentrate or dilute solubles) except the addition of clay. By analogy to the above steam reforming chemistry, the carbon fed to FBSR (coal in this instance) produces H2 and CO. For organic compounds in the waste stream which undergo pyrolysis to form various hydrocarbons, the reducing environment is generated by the following reaction: CnHm(g) + nH2O(g) nCO(g) + (n + m/2)H2(g)
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Yvette Collazo June 15, 2010 281 APPENDIX C Page 22 Similarly, the nitrates contained in the liquid waste are reduced to 2NaNO3(g) + 3C(s) 2NO(g) + 3CO(g) + Na2O(s) In the steam environment, the sodium oxide is transferred to sodium hydroxide: Na2O(s) + H2O(g) 2NaOH(s,l) yielding the overall reaction 2NaNO3(g) + 3C(s) + H2O(g) 2NO(g) + 3CO(g) + 2NaOH(s,l) 2NaNO3(g) + 2C(s) + H2O(g) 2NO2(g) + 2CO(g) + 2NaOH(l,s) The NO and NO2 are further reduced to nitrogen gas by the reaction of CO, C, or H2 generated from the reaction of the organic material with steam as shown above. The nitrates can also be reduced by the addition of a catalyst or a metal. For example: 2NaNO3(g) + 5Fe(s) + H2O(g) N2(g) + 5FeO(s) + 2NaOH(s,l) The second fluidized bed of the FBSR process operates in an oxidizing environment and is referred to as the Carbon Reduction Reformer, or CRR. The fluidizing gases are the off-gas from the first stage and added oxygen. Its function is to gasify carbon fines carried over in the process gases from the DMR, oxidize CO and H2 to CO2 and water, and convert trace acid gases to stable alkali compounds by reacting these acids with the bed media consisting of calcium carbonate and/or calcium silicate particles. The addition of bulk aluminosilicates to the fluidized bed results in the production of anhydrous feldspathoid phases such as sodalite. The sodalite family of minerals (including nosean) are unique because they have cage-like structures formed of aluminosilicate tetrahedra. The remaining feldspathoid minerals, such as nepheline, have a silica “stuffed derivative” ring type structure. The cage structures are typical of sodalite and/or nosean phases where leach testing has indicated that the cavities in the cage structure retain anions and/or radionuclides which are ionically bonded to the aluminosilicate tetrahedra and to sodium cation. Sodalite has the formula Na8[Al6Si6O24](Cl2). In sodalites and analogues with sodalite topologies, the cage is occupied by two sodium and two chlorine ions. When the 2NaCl are replaced by Na2SO4, the mineral phase is known as nosean, (Na6[Al6Si6O24](Na2SO4)). Since the Cl, SO4, and/or S2, are chemically bonded and physically restricted inside the sodalite cage structure, these species do not readily leach out of the respective FBSR waste form mineral phases. Thus, FBSR waste forms can be useful for immobilizing these species to prevent their leaching into groundwater. Other minerals in the sodalite family, namely hauyne and lazurite which are also cage structured minerals, can accommodate either (SO4=) or (S=) depending on the REDOX of the sulfur during the steam reforming process. Sodalite minerals are known
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Yvette Collazo 282 15, 2010 June APPENDIX C Page 23 to accommodate Be in place of Al and S2 in the cage structure along with Fe, Mn, and Zn, e.g., helvite (Mn4[Be3Si3O12]S), danalite (Fe4[Be3Si3O12]S), and genthelvite (Zn4[Be3Si3O12]S). These cage-structured sodalites were minor phases in HLW supercalcine waste forms and were found to retain Cs, Sr, and Mo into the cage-like structure, e.g., Mo as Na6[Al6Si6O24](NaMoO4)2. In addition, sodalite structures are known to retain B, Ge, I, and Br in the cage-like structures. Indeed, waste stabilization at Idaho National Laboratory currently uses a glass-bonded sodalite ceramic waste form (CWF) for disposal of electrorefiner wastes for sodium-bonded metallic spent nuclear fuel from the EBR II fast breeder reactor.
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Yvette Collazo June 15, 2010 283 APPENDIX C Page 24 Attachment F: Joule Heated Melters The DOE-EM program for immobilizing high-level waste currently utilizes Joule- heated melters (JHMs) to produce high-level waste waste glass. In Joule heating an electric current is passed through a material, in this case glass. The internal resistance of the material causes the electric currents to be dissipated as heat. A JHM is usually lined with refractory, and the glass is Joule heated by electricity transferred through the melt between nickel-chromium alloy electrodes, usually Inconel. The nominal melt temperature in JHMs is 1150°C, which is only 200°C lower than the melting point of the Inconel electrodes. These melters can be calcine fed or slurry fed and vitrification is a continuous or semi-continuous process. JHM’s have been used for waste glass production in the United States, France, and Japan because of the high production rate and high glass quality. The size of these systems is limited only by the replacement crane capacity since all the structural support is provided by a stainless steel shell which contains the refractory. The Defense Waste Process Facility at Savannah River Site is the largest production melter of this type ever built. A larger one is under construction for use at the Waste Treatment Plant at the Hanford Site and replacement of this system (due to its size) is by rail instead of by crane.
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Yvette Collazo 2June 15, 2010 84 APPENDIX C Page 25 Attachment G: Reviewer Acknowledgments This report has been reviewed in draft form by individuals chosen for their diverse perspectives and technical expertise, in accordance with procedures approved by the National Research Council Report Review Committee. The purpose of this independent review is to provide candid and critical comments that will assist the institution in making the published report as sound as possible and to ensure that the report meets institutional standards for objectivity, evidence, and responsiveness to the study charge. The content of the review comments and draft manuscript remains confidential to protect the integrity of the deliberative process. We wish to thank the following individuals for their participation in the review of this report: Patricia Culligan, Columbia University George Keller (NAE), Mid-Atlantic Technology, Research and Innovation Center Alexandra Navrotsky (NAS), University of California, Davis Alfred Sattelberger, Argonne National Laboratory Carl Steefel, Lawrence Berkeley National Laboratory Etienne Vernaz, CEA, Nuclear Energy Division, Marcoule Raymond Wymer, Oak Ridge National Laboratory (retired) Although the reviewers listed above have provided many constructive comments and suggestions, they were not asked to endorse the conclusions or recommendations, nor did they see the final draft of the report before its release. The review of this report was overseen by Ed Przybylowicz, appointed by the National Research Council, who was responsible for making certain that an independent examination of this report was carried out in accordance with institutional procedures and that all review comments were carefully considered. Responsibility for the final content of this report rests entirely with the authoring committee and the National Research Council.