2

Background and Study Task

The Department of Energy’s Office of Environmental Management (DOE-EM) is responsible for cleaning up radioactive waste and environmental contamination resulting from five decades of nuclear weapons production and testing. The cleanup program is arguably the largest such effort in the world, encompassing some 2 million acres at more than 100 sites across the United States (Figure 2.1). The program was initiated about two decades ago and is scheduled to last for another four to five decades (Figure 2.2).

A major focus of this program involves the retrieval and processing of stored waste to reduce its volume and incorporation of this waste into suitable waste forms to facilitate safe handling and disposal. This report, which was requested by DOE-EM, examines requirements for waste form technology and performance in the DOE-EM cleanup program. It is intended to provide information to DOE-EM to support improvements in methods for processing waste and selecting and fabricating waste forms for disposal. The complete study task is shown in Box 2.1.

The DOE-EM cleanup program is successfully processing waste and producing waste forms at several sites. However, as discussed in Section 2.2, the cleanup program is planned to last for several decades and cost several hundreds of billions of dollars. DOE-EM recognizes that during the remaining decades of this program there will be opportunities to incorporate emerging developments in science and technology on waste forms, waste form production technologies, and waste form/disposal system modeling. Incorporating new science and technology could lead to increased program



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2 Background and Study Task T he Department of Energy’s Office of Environmental Management (DOE-EM) is responsible for cleaning up radioactive waste and environmental contamination resulting from five decades of nuclear weapons production and testing. The cleanup program is arguably the larg- est such effort in the world, encompassing some 2 million acres at more than 100 sites across the United States (Figure 2.1). The program was initi- ated about two decades ago and is scheduled to last for another four to five decades (Figure 2.2). A major focus of this program involves the retrieval and processing of stored waste to reduce its volume and incorporation of this waste into suit- able waste forms to facilitate safe handling and disposal. This report, which was requested by DOE-EM, examines requirements for waste form technol- ogy and performance in the DOE-EM cleanup program. It is intended to provide information to DOE-EM to support improvements in methods for processing waste and selecting and fabricating waste forms for disposal. The complete study task is shown in Box 2.1. The DOE-EM cleanup program is successfully processing waste and producing waste forms at several sites. However, as discussed in Section 2.2, the cleanup program is planned to last for several decades and cost several hundreds of billions of dollars. DOE-EM recognizes that during the remain- ing decades of this program there will be opportunities to incorporate emerging developments in science and technology on waste forms, waste form production technologies, and waste form/disposal system modeling. Incorporating new science and technology could lead to increased program 15

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16 WASTE FORMS TECHNOLOGY AND PERFORMANCE FIGURE 2.1 Locations of current sites in the DOE-EM cleanup program. Sites la- Figure 2.1.eps beled as active have ongoing cleanup projects involving high-level waste/transuranic bitmap waste or low-level waste/mixed low-level waste. SOURCE: DOE-EM: http://www.em.doe.gov/pages/siteslocations.aspx. Last ac- cessed March 7, 2010. efficiencies, reduced lifecycle costs and risks, and advanced scientific under- standing of, and stakeholder confidence in, waste form behavior in different disposal environments (NRC, 2010). 2.1 BACKGROUND ON WASTE FORMS The term waste form is defined by the International Atomic Energy Agency (2003) as waste in its physical and chemical form after treatment and/or conditioning (resulting in a solid product) prior to packaging. The term is defined by the American Society for Testing and Materials (ASTM) standards1 and in federal regulations2 as a radioactive waste material and 1For example, ASTM C-1174, C-1454, and C-1571; see Chapter 5. 2Title 10, Part 60 of the Code of Federal Regulations, Disposal of High-Level Radioactive Wastes in Geologic Repositories; see Part 60.2.

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17 BACKGROUND AND STUDY TASK FIGURE 2.2 Projected dates for completion of DOE-EM site cleanup. This schedule does not reflect accelerated cleanup schedules resulting from work funded by the Figure 2.2.eps 2009 American Recovery and Reinvestment Act. bitmap SOURCE: Data from the DOE FY 2011 Congressional Budget Request. Available at http://www.mbe.doe.gov/budget/11budget/Content/Volume%205.pdf. Last accessed on August 25, 2010. any encapsulating or stabilizing matrix in which it is incorporated. A wide range of materials are potentially usable as waste forms; these include amorphous materials (e.g., glass), crystalline materials (e.g., ceramics, min- eral analogues, metals, cements), or a combination of amorphous and crystalline materials (e.g., glass-ceramic materials). These materials are described in some detail in Chapter 3. The solidification, embedding, or encapsulation of radioactive and chemically hazardous waste to create a waste form is referred to as immo- bilization. Radioactive and chemically hazardous constituents in the waste can be immobilized into a waste form material through two processes: Constituents can be (1) bound into the material at atomic scale (chemical incorporation) or (2) physically surrounded and isolated by the mate- rial (encapsulation). Some waste form materials can perform both func- tions. Additional discussion of immobilization mechanisms is provided in Chapter 3. Several factors must be considered when selecting a waste form material for immobilizing a specific waste stream. The key considerations include the following:

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18 WASTE FORMS TECHNOLOGY AND PERFORMANCE BOX 2.1 Statement of Task The National Academies will examine the requirements for waste form tech- nology 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 sys- tems associated with high-cost waste streams such as high-level tank waste and calcine but include some consideration of low-level and trans- uranic waste disposal. • Scientific, technical, regulatory, and legal factors that underpin require- ments 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. • Waste loading: The waste form must be able to accommodate a sig- nificant amount of waste (typically 25-45 weight percent) to mini- mize volume, thereby minimizing the space needed for disposal. • Ease of production: Fabrication of the waste form should be accom- plished under reasonable conditions, including low temperatures and, ideally, in an air atmosphere, using well-established methods to minimize worker dose and the capital cost of plant. • Durability: The waste form should have a low rate of dissolution when in contact with water to minimize the release of radioactive and chemical constituents. • Radiation stability: The waste form should have a high tolerance to radiation effects from the decay of radioactive constituents. Depend-

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19 BACKGROUND AND STUDY TASK ing on the types of constituents being immobilized, the waste form could be subjected to a range of radiation effects, including ballistic effects from alpha decay and ionizing effects from decay of fission product elements. • Chemical flexibility: The waste form should be able to accom- modate a mixture of radioactive and chemical constituents with minimum formation of secondary phases that can compromise its durability. • Availability of natural analogues: Because direct laboratory test- ing of the waste forms over the relevant time scales for disposal (typically 103-106 years for DOE-managed wastes) is not possible, the availability of natural mineral or glass analogues may provide important clues about the long-term performance of the material in the natural environment, thereby building confidence in the extrapolated behavior of the waste form after disposal. • Compatibility with the intended disposal environment: The waste form should be compatible with the near-field environment3 of the disposal facility. The near-field environment provides the physical and chemical conditions that are favorable for maintaining waste form integrity over extended periods, which helps to slow the release of constituents and their transport out of the facility. 2.2 BACKGROUND ON DOE-EM WASTE STREAMS The production of nuclear materials for the U.S. defense program began during the Manhattan Project in World War II and continued through the end of the Cold War.4 A large number of processes were used to produce nuclear materials. These included isotope enrichment and separation; fuel and target fabrication, dissolution, and chemical separation; and casting, machining, and plating. The wastes generated by these operations ranged from slightly contaminated trash to highly radioactive and chemically toxic liquids. These wastes were managed using practices analogous to those for other process industries of the era, including disposal of solid waste in land- fills, disposal of liquid wastes in ponds and through underground injection, and temporary storage. Some highly radioactive liquid wastes have been in temporary storage at DOE sites for more than six decades. 3 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). 4 The Cold War ended in 1991 with the breakup of the Soviet Union.

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20 WASTE FORMS TECHNOLOGY AND PERFORMANCE Information about these processes and waste streams are available from a variety of sources, including DOE reports (e.g., DOE, 1995, 1997, 1998), reports by other federal agencies (e.g., OTA, 1991a,b), reports from national laboratories (Gephart, 2003), and reports from the National Acad- emies (e.g., NRC, 2001a,b,c, 2002a,b, 2003, 2006). DOE-EM maintains an online database, the Central Internet Database5 (CID), which contains information on spent fuel, radioactive waste, facilities, and contaminated media being managed at current and former production facilities. The principal waste streams that are being managed by DOE-EM are shown in Table 2.1.6 As can be seen in this table, the volumes of waste being managed are varied and substantial, although it is important to note that not all waste has been well characterized or inventoried. As can also be seen in this table, some waste form and disposition decisions have not yet been made, particularly for orphan7 waste streams. DOE-EM’s current strategies for treatment and disposition of these waste streams can be summarized as follows (see Box 2.2 for definitions of waste types): • Spent nuclear fuel (SNF) is being consolidated at the Hanford Site (Washington), Idaho Site, and Savannah River Site (South Carolina). Most SNF will be dried and stored in canisters suitable for deep disposal in a Federal repository. Some SNF at the Idaho and Savannah River Sites is being stabilized by melting (Savannah River) or metallurgical processing (Idaho). • High-level radioactive waste (HLW) at West Valley, New York, has been immobilized in borosilicate glass for eventual disposal in a Federal repository. However, residual liquid and sludge heels remain in the tanks. • HLW in the form of sludge, precipitated salt, and liquid is cur- rently stored in tanks at the Hanford and Savannah River Sites. At Savannah River, this waste is being retrieved and separated into two process streams: A high-activity stream that is being immobi- lized in a borosilicate glass waste form for deep disposal in a Fed- eral repository, and a low-activity stream that is being immobilized in a cement waste form (Saltstone) for shallow disposal onsite. 5 The CID is available at http://cid.em.doe.gov/Pages/CIDHome.aspx. Last accessed on August 25, 2010. 6 DOE-EM is responsible for cleanup of legacy wastes (including surplus facilities) that have been transferred into the cleanup program. There are a large number of facilities in the DOE complex that will continue to operate for decades and generate new wastes. Those facilities and wastes are not currently part of the cleanup program, but they could be transferred into that program in the future. 7 A waste stream is referred to as orphan when it has no clear-cut disposition pathway.

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21 BACKGROUND AND STUDY TASK TABLE 2.1 Principal Waste Streams, Waste Forms, and Disposition Pathways for the DOE-EM Cleanup Program Approximate Current Principal Likely Disposition Waste Formsa Waste Stream Quantities Pathways As isb Spent nuclear fuel 2,400 MTHM Deep disposal (Federal repository) High-level waste 340,000 m3 Tank waste HAW: Glass HAW: Deep disposal LAW: Grout, (Federal repository) glass, other LAW: Shallow disposal 4,400 m3 Bin waste Glass-ceramic Deep disposal (Federal repository) 164,000 m3 As isc Transuranic waste Deep disposal (WIPP) 1,400,000 m3 LLW: As isd Low-level waste (including Shallow disposal mixed LLW) Mixed LLW: Grout, othere > 2 million m3 Mill tailings (byproduct As is Shallow disposal waste) Depleted uranium 737,000 MT Uranium oxide Shallow disposal Plutonium and uranium 108 MT MOX fuel Deep disposal (Federal residues Glass repository) Excess facilitiesf 5,200 As is for Shallow disposal for decommissioning LLW; WIPP for TRU waste waste Orphan waste streams 5 m3 TBDg Cs and Sr capsules TBD Other various TBD TBD NOTES: HAW = high-activity waste; LAW = low-activity waste; LLW = low-level radioactive waste; MT = metric tonnes; MTHM = metric tonnes of heavy metal; TBD = to be determined; TRU = transuranic; WIPP = Waste Isolation Pilot Plant. a The entry “As is” indicates that the waste will be disposed of in its current form, although it may be conditioned (e.g., dried, sorted, volume reduced, and/or packaged) prior to disposal. b Small quantities of SNF at Savannah River and Idaho are also being reprocessed. c Liquid sodium-bearing waste at the Idaho Site will be steam reformed. d Some LLW may require treatment and immobilization prior to disposal. e See NRC (1999). f Includes nuclear, radiological, and industrial facilities. g The Draft Tank Closure and Waste Management Environmental Impact Statement for the Hanford Site, Richland, Washington (DOE/EIS-0391, October 2009) identifies treatment al- ternatives that involve the retrieval of cesium and strontium from the capsules for treatment in the Waste Treatment Plant. SOURCES: Quantity data: Mill tailings: DOE, 2001; Other: Department of Energy FY 2011 Congressional Budget Request; ROO, 2002.

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22 WASTE FORMS TECHNOLOGY AND PERFORMANCE BOX 2.2 Types of Waste Materials in the DOE Inventory The following terms are used in this report to refer to the materials that are being managed by the DOE cleanup program: Spent nuclear fuel (SNF) is defined by the Nuclear Waste Policy Act (2 U.S.C. §10101 et seq., 1982) “as fuel that has been withdrawn from a nuclear reactor following irradiation, the constituent elements of which have not been separated by reprocessing.” ln the United States, SNF is not a waste material unless declared to be one. High-level radioactive waste (HLW) is defined by the Nuclear Waste Policy Act as 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 other highly radioactive material that the Nuclear Regulatory Commission, consistent with existing law, determines by rule to require permanent isolation. Low-level radioactive waste (LLW) is defined in the Nuclear Waste Policy Act as radioactive material that is not high-level radioactive waste, spent nuclear fuel, transuranic waste, or 11(e)(2) byproduct material (mill tailings) that the Nuclear Regulatory Commission, consistent with existing law, classifies as low-level radio- active waste. Hazardous waste is defined by the EPA in Title 40 of the Code of Federal Regulations, Parts 260 and 261. This waste is toxic or otherwise hazardous be- cause of its chemical properties. Waste can be designated as hazardous in any of three ways: (1) It contains one or more of more than 700 materials listed as hazardous by the EPA; (2) it exhibits one or more hazardous characteristics, which include ignitability, corrosivity, chemical reactivity, or toxicity; or (3) it arises from treating waste already designated as hazardous. Mixed low-level waste (MLLW) meets the above definitions of both low-level waste and hazardous waste and is therefore subject to dual regulations. Transuranic (TRU) waste is defined in Title 40, Part 191 (Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes) as waste containing more than 100 nanocuries of alpha-emitting transuranic isotopes, with half-lives greater than twenty years, per gram of waste, except for: (1) High-level radioactive wastes; (2) wastes that the Department [of Energy] has determined, with the concurrence of the [EPA] Administrator, do not need the degree of isolation required by this part; or (3) wastes that the [Nuclear Regulatory] Commission has approved for disposal on a case-by-case basis in accordance with Title 10, Part 61 of the Code of Federal Regulations. Mixed transuranic (MTRU) waste meets the definitions of both transuranic and hazardous wastes. Other wastes being managed by DOE include special nuclear materials (ura- nium and plutonium), source materials such as depleted uranium, and byproduct materials such as the tailings from mining and milling of uranium ores.

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23 BACKGROUND AND STUDY TASK HLW at Hanford will be processed in a similar fashion. However, current plans call for about a third of the low-activity stream at Hanford to be immobilized in borosilicate glass for onsite disposal. Plans for immobilizing the other two-thirds of the low-activity stream are still being developed. HLW in the form of granular calcine is stored in bins at the Idaho Site. Current plans call for this waste to be immobilized by hot isostatic press- ing, with or without additives, to produce a glass-ceramic waste form (see NRC, 2010, and Chapter 4 of this report) for deep disposal in a Federal repository. • Most transuranic (TRU) waste will be packed into barrels, boxes, and shielded casks (i.e., packaged) and disposed of at the Waste Isolation Pilot Plant (WIPP) in New Mexico. Liquid TRU waste at the Idaho Site will be immobilized by steam reforming (see NRC, 2010, and Chapter 4) prior to disposal at WIPP. • Mill tailings waste is being disposed of in near-surface disposal cells with engineered covers. • Most LLW will be packaged and disposed of in DOE and com- mercial shallow disposal facilities.8 However, there are some LLW streams (e.g., spent resins) that may require processing to make them suitable for disposal. • Depleted uranium (in the form of uranium hexafluoride) is being stored at the Portsmouth (Ohio) and Paducah (Kentucky) sites. It will be converted to uranium oxide and packaged for shallow disposal. • Some plutonium that is excess to U.S. defense needs will be used to produce mixed oxide fuel for commercial reactors. Other plu- tonium and uranium residues will be packaged and disposed of at WIPP or in a Federal repository. • Facilities will be demolished, disposed of in place, or reused for other purposes. Decommissioning of the facilities will generate TRU waste, LLW, and nonhazardous debris. • There are a number of orphan waste streams that lack clear dispo- sition pathways, either because they are not HLW, TRU waste, or LLW, or because they do not meet waste acceptance criteria (see Chapter 8) for disposal. These orphan waste streams include, for example, actinide targets, beryllium neutron reflectors, and highly 8 The disposal pathway for Greater-than-Class C LLW is still under development by DOE. See http://www.gtcceis.anl.gov/. Last accessed on August 25, 2010.

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24 WASTE FORMS TECHNOLOGY AND PERFORMANCE contaminated process equipment. Additionally, wastes generated during cleanup operations9 may also become orphan. The disposal pathways for SNF/HLW, TRU waste, and LLW are estab- lished in U.S. laws and regulations. SNF/HLW and TRU waste require deep disposal hundreds of meters below the Earth’s surface. Defense-related TRU wastes are currently being disposed of at WIPP. SNF/HLW will be disposed of in a Federal repository. Yucca Mountain, Nevada, has been designated by the Federal government as the site for this repository, but efforts are underway within the Executive Branch to withdraw this site from consid- eration. LLW is being disposed of in shallow facilities within 10 meters or so of the Earth’s surface at a number of sites in the United States. According to the Fiscal Year 2011 DOE Budget,10 total life cycle costs for the DOE-EM cleanup program are currently estimated to be between $275 billion and $329 billion. HLW cleanup is the largest lifecycle cost ele- ment of the cleanup program, with lifecycle costs estimated to be between $87 billion and $117 billion. The Hanford Site, Idaho Site, and Savannah River Site are responsible for the majority of past and projected lifecycle cleanup costs, totaling almost $200 billion (Figure 2.3). Cleanup of these three sites and the gaseous diffusion plants in Tennessee and Kentucky will also take the longest to complete: projected cleanup schedules range from about 2030 to beyond 2060 (see Figure 2.2). 2.3 STUDY PLAN The National Academies appointed the Committee on Waste Forms Technology and Performance to carry out this study. It consists of 11 members with expertise that spans the scientific and engineering disciplines relevant to the study task, including chemical and process engineering; geo- sciences; materials science; radiochemistry; risk assessment; waste disposal regulations; waste form performance; and waste management practices and technologies. Biographical sketches of the committee members are provided in Appendix A. The information used in this study was collected from several sources. The committee availed itself of the voluminous existing scientific and engi- neering literature on waste forms and processing technologies. The committee has made no attempt to summarize this literature in this report; instead, it has cited key papers and review articles where needed to support its discussions. 9 These include gaseous and liquid effluents and solid wastes, for example, process conden- sates, scrubber wastes, spent resins, and failed equipment. 10 Available at http://www.mbe.doe.gov/budget/11budget/Content/Volume%205.pdf. Last accessed August 25, 2010.

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25 BACKGROUND AND STUDY TASK FIGURE 2.3 Lifecycle costs for DOE-EM site cleanup. Figure 2.3.eps SOURCE: Data from the DOE FY 2011 Congressional Budget Request. Available at bitmap http://www.mbe.doe.gov/budget/11budget/Content/Volume%205.pdf. Last accessed on August 25, 2010. The committee also obtained information through a series of brief- ings by representatives of DOE and other organizations, 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, Idaho Site, Savannah River Site, and their associated national labora- tories (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 tech- nical discussions with site and laboratory staff. The committee also orga- nized 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 Appendix B.

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26 WASTE FORMS TECHNOLOGY AND PERFORMANCE At the request of DOE-EM, the committee issued an interim report to provide timely information for Fiscal Year 2011 technology planning (NRC, 201011). That report, which was released to the public on June 15, 2010, identified opportunities associated with the last three bullets of the statement of task (see Box 2.1). The interim report is provided in its entirety in Appendix C of this report. This final report addresses the statement of task in its entirety. How- ever, in addressing the task, the committee decided to focus on waste forms and processing technologies for HLW, because HLW cleanup has the longest schedule, highest cost, highest risk, and is arguably DOE-EM’s most diffi- cult technical challenge (see, for example, DOE, 1998, 2010; NRC, 2001a, 2006). HLW is also a major focus of the DOE-EM Science and Technology Roadmap (DOE, 2008; see also NRC, 2009). Most other waste types will be much less challenging and expensive to manage and dispose of than HLW. As noted in Table 2.1, most TRU waste and LLW are being disposed of “as is”—that is, without processing it into waste forms—although some conditioning (i.e., drying, sorting, volume reduction, and packing) is being undertaken. Additionally, the process for characterizing TRU waste prior to disposal is time consuming and expen- sive, but these characterization issues have been addressed in previous National Research Council reports (NRC, 2002b, 2004). DOE is currently storing its SNF in pools (wet storage) and casks (dry storage). Additionally, some corroded aluminum-clad SNF at Savannah River has been stabilized by processing it into metal. DOE plans to eventu- ally direct dispose its SNF in a geologic repository assuming that it meets repository waste acceptance criteria (see Chapter 8). However, with the apparent cancellation of the Yucca Mountain project, extended storage of SNF might be required at DOE sites until another repository is identified, licensed, and opened. In this case, SNF in wet storage might need to be stabilized to reduce corrosion (see NRC, 2003). At present, tank waste retrieval and closure are limited by schedules for treating and immobilizing HLW in the Defense Waste Processing Facil- ity, 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 for immobilizing calcine HLW 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. 11 Available at http://www.nap.edu/catalog.php?record_id=12937. Last accessed on August 25, 2010. See Appendix C

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27 BACKGROUND AND STUDY TASK 2.4 REPORT ORGANIZATION This report is organized into eight chapters to address the statement of task for the study. The chapter topics and their relation to the study charges in the statement of task (i.e., the bulleted items in Box 2.1) are as follows: • Chapter 2 (this chapter) provides background on the study. • Chapter 3 describes the physical and chemical properties of waste form materials that are potentially relevant to the DOE-EM cleanup program (addresses Charge 1 in Box 2.1). • Chapter 4 describes key technologies for producing waste forms (Charge 4). • Chapter 5 describes how testing is used to elucidate waste form properties and support modeling of long-term waste form perfor- mance in disposal environments (Charge 3). • Chapter 6 provides a brief description of disposal environments, systems, and processes that can affect waste form performance (Charge 1). • Chapter 7 describes the use of models for evaluating waste form performance in disposal environments (Charge 3). • Chapter 8 describes the legal and regulatory factors that underpin requirements for waste form performance (Charge 2). • Chapter 9 provides examples of possible opportunities for new and improved waste form materials, processing technologies, and computational modeling (Charges 4 and 5). A glossary of terms and an acronym list are provided in Appendixes D and E, respectively. REFERENCES DOE [U.S. Department of Energy]. 1995. Closing the Circle on the Splitting of the Atom: The Environmental Legacy of Nuclear Weapons Production in the United States and What the Department of Energy is Doing about It, Office of Environmental Management, Washington, D.C. DOE. 1997. Linking Legacies: Connecting the Cold War Nuclear Weapons Production Pro- cesses to Their Environmental Consequences, DOE/EM-0319, Office of Environmental Management, Washington, D.C. DOE. 1998. Accelerating Cleanup: Paths to Closure, DOE/EM-0362, Office of Environmental Management, Washington, D.C. DOE. 2001. Summary Data on the Radioactive Waste, Spent Nuclear Fuel, and Contaminated Media Managed by the U.S. Department of Energy, DOE/EM-00-0384, Office of Envi- ronmental Management, Washington, D.C. (April). DOE. 2008. Engineering and Technology Roadmap: Reducing Technical Risk and Uncertainty in the EM Program, Office of Environmental Management, Washington, D.C., Available at http://www.em.doe.gov/pdfs/FINAL%20ET%20Roadmap%20_3-5-08_.pdf.

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28 WASTE FORMS TECHNOLOGY AND PERFORMANCE DOE. 2010. Technical Evaluation of Strategies for Transforming the Tank Waste System: Tank Waste System Integrated Project Team Final Report, Office of Environmental Manage- ment, Washington, D.C. (January). Gephart, R. E. 2003. Hanford: A Conversation about Nuclear Waste and Cleanup, Battelle Press, Richland, Wash. IAEA [International Atomic Energy Agency]. 2003. IAEA Radioactive Waste Management Glossary, 2003 Edition, Available at http://www-pub.iaea.org/MTCD/publications/PDF/ Pub1155_web.pdf. NRC [National Research Council]. 1999. The State of Development of Waste Forms for Mixed Wastes, National Academy Press, Washington, D.C. NRC. 2001a. Research Needs for High-Level Waste Stored in Tanks and Bins at U.S. Depart- ment of Energy Sites, National Academy Press, Washington, D.C. NRC. 2001b. Research Opportunities for Deactivating and Decommissioning Department of Energy Facilities, National Academy Press, Washington, D.C. NRC. 2001c. Science and Technology for Environmental Cleanup at Hanford, National Academy Press, Washington, D.C. NRC. 2002a. Research Opportunities for Managing the Department of Energy’s Transuranic and Mixed Wastes, National Academies Press, Washington, D.C. NRC, 2002b. Characterization of Remote-Handled Transuranic Waste for the Waste Isolation Pilot Plant, National Academies Press, Washington, D.C. NRC. 2003. Improving the Scientific Basis for Managing DOE’s Excess Nuclear Materials and Spent Nuclear Fuel, National Academies Press, Washington, D.C. NRC. 2004. Improving the Characterization Program for Contact-Handled Transuranic Waste Bound for the Waste Isolation Pilot Plant, National Academies Press, Washington, D.C. NRC. 2006. Tank Waste Retrieval, Processing, and On-Site Disposal at Three Department of Energy Sites: Final Report, National Academies Press, Washington, D.C. NRC. 2009. Advice on the Department of Energy’s Cleanup Technology Roadmap: Gaps and Bridges, National Academies Press, Washington, D.C. NRC. 2010. Waste Form Technologies and Performance: Interim Report, National Academies Press, Washington, D.C. OECD-NEA [Organisation for Economic Co-Operation and Development-Nuclear Energy Agency]. 2003. Engineered Barrier Systems and the Safety of Deep Geological Reposito- ries: State-of-the-Art Report, OECD-NEA, Paris, France. OTA [Office of Technology Assessment]. 1991a. Complex Cleanup: The Environmental Legacy of Nuclear Weapons Production, U.S. Government Printing Office, Washington, D.C. OTA. 1991b. Long-Lived Legacy: Managing High-Level and Transuranic Waste at the DOE Nuclear Weapons Complex, U.S. Government Printing Office, Washington, D.C. ROO [DOE Richland Operations Office]. 2002. Waste Encapsulation and Storage Facility (WESF) Fact Sheet, REG-0275, U.S. Department of Energy, Richland, Wash.