ZEOLITE WASTE FORM

In the proposed electrometallurgical process, the fission product cations that are less easily reduced to metals (e.g., strontium, cesium, iodine, selenium) and trace amounts of the actinides would be incorporated in a synthetic zeolite matrix.5 This waste form has not been finalized by ANL, and only preliminary information on its potential radionuclide release rate (mass of a particular radionuclide per unit of surface area per unit of time) into the environment was available for evaluation by the committee. 6

Release of radionuclides from a zeolite waste matrix may occur by an ion exchange mechanism that is fundamentally different from the dissolution of matrix material that occurs for other HLW matrices such as the UO2 matrix of LWR spent fuel, borosilicate glass, or a crystalline waste form such as Synroc. This mechanism depends not on the dissolution rate of the zeolite matrix but rather on the partition coefficients for radionuclides between the zeolite and contacting groundwater. Consequently, the release rates of radionuclides from the zeolite waste form might be controlled by partitioning rather than the dissolution rate of the matrix or radioelement solubilities and could therefore be a function of the volumetric flow rate of water per waste container, the equilibrium concentration of the nuclide in the zeolite, and the equilibrium constant for binding of that nuclide to the zeolite. Standard tests of dissolution rate may therefore be inadequate for determining the rates of release of radionuclides from the zeolite waste form. ANL's draft test plan for evaluating the rates of release of radionuclides from the electrometallurgical process's waste forms was unavailable for review by the committee, but it should be reviewed at the earliest opportunity to assure that it will assess performance broadly and appropriately.

Open issues in addition to its baseline performance concern the long-term effects of “aging” on the zeolite waste form. Radioactive decay would convert one element to another, resulting in changes in the ionic charge and ionic radius of species trapped within the zeolite cages. Whether such changes would increase or decrease the resulting “aged” zeolite's effective release rate is not clear. Similarly, alpha-recoil effects from decay of actinides could lead to deleterious “aging” effects on the long-term performance of the zeolite waste form.

CLADDING-METAL WASTE FORM

A waste fraction intended for direct geologic disposal would be produced from either Zircaloy or stainless steel cladding of the spent fuel. The bulk composition of this fraction would be approximately that of the cladding, and the waste form would be produced as a eutectic mixture of zirconium-rich and iron-rich phases. The fission products that least easily undergo electrochemical oxidation would remain at the anode in metallic form and would accompany the cladding material in this waste product. These metals would include nickel, technetium, zirconium, molybdenum, the platinum group elements, and possibly tin. Depending on the ratio of the mass of the initial cladding and structural elements to that of the fuel matrix, the processed cladding-metal waste form could have a mass fraction of fission products higher or lower than

5  

As mentioned above, ANL has recently begun consideration of a modified process in which all of the transuranic elements would also be diverted into this waste stream. However, this alternative was not considered in detail by the committee.

6  

W.M. Nutt, R.N. Hill, and D.B. Bullen, “Performance Assessment Modeling of High Level Nuclear Wasteforms from the Pyroprocess Fuel Cycle,” High Level Radioactive Waste Management, Proceedings of the sixth annual conference, Las Vegas, Nev., 1995.



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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL ZEOLITE WASTE FORM In the proposed electrometallurgical process, the fission product cations that are less easily reduced to metals (e.g., strontium, cesium, iodine, selenium) and trace amounts of the actinides would be incorporated in a synthetic zeolite matrix.5 This waste form has not been finalized by ANL, and only preliminary information on its potential radionuclide release rate (mass of a particular radionuclide per unit of surface area per unit of time) into the environment was available for evaluation by the committee. 6 Release of radionuclides from a zeolite waste matrix may occur by an ion exchange mechanism that is fundamentally different from the dissolution of matrix material that occurs for other HLW matrices such as the UO2 matrix of LWR spent fuel, borosilicate glass, or a crystalline waste form such as Synroc. This mechanism depends not on the dissolution rate of the zeolite matrix but rather on the partition coefficients for radionuclides between the zeolite and contacting groundwater. Consequently, the release rates of radionuclides from the zeolite waste form might be controlled by partitioning rather than the dissolution rate of the matrix or radioelement solubilities and could therefore be a function of the volumetric flow rate of water per waste container, the equilibrium concentration of the nuclide in the zeolite, and the equilibrium constant for binding of that nuclide to the zeolite. Standard tests of dissolution rate may therefore be inadequate for determining the rates of release of radionuclides from the zeolite waste form. ANL's draft test plan for evaluating the rates of release of radionuclides from the electrometallurgical process's waste forms was unavailable for review by the committee, but it should be reviewed at the earliest opportunity to assure that it will assess performance broadly and appropriately. Open issues in addition to its baseline performance concern the long-term effects of “aging” on the zeolite waste form. Radioactive decay would convert one element to another, resulting in changes in the ionic charge and ionic radius of species trapped within the zeolite cages. Whether such changes would increase or decrease the resulting “aged” zeolite's effective release rate is not clear. Similarly, alpha-recoil effects from decay of actinides could lead to deleterious “aging” effects on the long-term performance of the zeolite waste form. CLADDING-METAL WASTE FORM A waste fraction intended for direct geologic disposal would be produced from either Zircaloy or stainless steel cladding of the spent fuel. The bulk composition of this fraction would be approximately that of the cladding, and the waste form would be produced as a eutectic mixture of zirconium-rich and iron-rich phases. The fission products that least easily undergo electrochemical oxidation would remain at the anode in metallic form and would accompany the cladding material in this waste product. These metals would include nickel, technetium, zirconium, molybdenum, the platinum group elements, and possibly tin. Depending on the ratio of the mass of the initial cladding and structural elements to that of the fuel matrix, the processed cladding-metal waste form could have a mass fraction of fission products higher or lower than 5   As mentioned above, ANL has recently begun consideration of a modified process in which all of the transuranic elements would also be diverted into this waste stream. However, this alternative was not considered in detail by the committee. 6   W.M. Nutt, R.N. Hill, and D.B. Bullen, “Performance Assessment Modeling of High Level Nuclear Wasteforms from the Pyroprocess Fuel Cycle,” High Level Radioactive Waste Management, Proceedings of the sixth annual conference, Las Vegas, Nev., 1995.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL that of the unprocessed matrix; mass fraction is one of the factors used in assessing the suitability of the waste form. The extent of partitioning of these radioelements between the two intergrown phases has not been established. The release rate for the cladding-metal waste form is a function of the matrix dissolution rate, the matrix surface area, and the mass fraction of nuclide within the metallic matrix. Standard techniques and test protocols for the measurement of matrix dissolution rates for nuclear waste forms are well established. The performance of this metal-matrix waste form has had only preliminary laboratory study, and a bulk dissolution rate of 5.0 g/m2 per yr has been reported.7 This value compares with a measured dissolution rate for the UO2 matrix of PWR spent fuel of about 3 g/m2 per yr under oxidizing conditions.8 The mass fraction of nuclides within the cladding waste form depends on the type of fuel, the fuel burnup, and the efficiency of the electrometallurgical separation. 7   Ibid. 8   W.J. Gray and D.M. Strachan, Mat. Res. Soc. Symp. Proc., Vol. 212, pp. 205-212, Materials Research Society, Pittsburgh, Penn., 1991.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL 5 EFFECT OF BROADER DOE-WIDE ISSUES ON PLANNING FOR ELECTROMETALLURGICAL R&D As discussed in Chapter 1, the Committee on Electrometallurgical Techniques for DOE Spent Fuel Treatment was charged with assessing the advantages and disadvantages of electrometallurgical processing as a candidate technology for disposition of DOE spent nuclear fuel (SNF) and advising the DOE on the continuation of R&D in this area. Although the committee summarizes its observations on the electrometallurgical process in the previous chapters of this report, several factors outside the committee's purview made it very difficult to evaluate in proper context the cost-effectiveness of the proposed process, suitability of the metallic waste form for long-term storage or geologic disposal, and nonproliferation implications. These factors and their impacts on the committee's evaluation of the electrometallurgical process are discussed in this chapter. NEED FOR A BROAD COMPREHENSIVE STRATEGY First and foremost, the committee was unable to determine that DOE has developed a broad comprehensive strategy covering interim management and ultimate disposition of DOE SNF from operation of DOE, U.S. commercial, and U.S. and foreign research reactors; DOE high-level and transuranic waste; and Excess highly enriched uranium, plutonium, and other transuranic materials. Any strategic plan will have various levels of uncertainty. For instance, efforts to develop waste forms have been hindered by the absence of applicable standards and regulations. Further, interim storage of DOE SNFs or their waste streams will be necessary for varying periods of time, depending on the availability and capacity of geologic repository facilities. Meanwhile, emerging ideas for the disposition of excess weapons fissile materials will bear on the overall strategy of managing DOE “waste.” Contributions toward development of a broad comprehensive strategy include the “Defense Nuclear Facilities Safety Board Recommendation 94-1 Implementation Plan,”1 several key environmental impact statements currently in preparation, 2 the “DOE Spent Nuclear Fuel Program Strategic Plan,”3 and the Performance Assessment of the Direct Disposal in Unsaturated Tuff of Spent Nuclear Fuel and High-Level 1   Department of Energy, Feb. 28, 1995. 2   See, e.g., “Programmatic Spent Nuclear Fuel Management and Idaho National Engineering Laboratory (INEL) Environmental Restoration and Waste Management Programs Final Environmental Impact Statement (FEIS),” report no. DOE/EIS-0203-D, DOE Idaho Operations Office, Idaho Falls, Idaho, June, 1994. 3   DOE, December, 1994.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL Waste Owned by U.S. Department of Energy.4 However, integration of these and other yet-to-be-developed strategic planning elements into a broad comprehensive DOE strategy remains to be accomplished. Also needed is sufficient dialogue with affected public, commercial, and governmental interests to develop a consensus that will provide the basis for the necessary long-term implementation of the strategy. On the basis of ongoing environmental impact considerations, much of the SNF or some of its constituent materials and other non-SNF materials may be co-disposed in a single geologic repository. However, the DOE has not established for these materials adequate disposition criteria that define acceptable waste forms, accesptability of direct disposal of SNF, and disposition of excess plutonium and highly enriched uranium.5 The absence of these important criteria precludes a full comparative analysis of the alternatives of (1) an SNF management policy based on improved long-term interim SNF storage and (2) a strategy based on near-term SNF processing to produce materials acceptable for final disposition. The schedule and cost implications of such trade-offs, which would result only from comprehensive studies of the options, would appear indispensable to DOE's establishing a SNF management policy. Considering the significant quantities of SNF, high-level and transuranic wastes, and excess enriched uranium and transuranic materials whose storage, treatment, and/or processing require a broad, comprehensive plan, and the large number of associated national and DOE site-specific activities that will be involved (e.g., transport, near-term storage, stabilization and extended improved storage, processing to acceptable waste forms, completion of required geologic repositories, and ultimate material disposition), it is clear that a broad, comprehensive strategy is needed. The strategy could be a multitiered collection of highly interrelated strategic plans dealing with individual activities necessary both nationally and at specific DOE sites. The strategy must also reflect associated plans developed by other federal organizations such as the Environmental Protection Agency and the U.S. Nuclear Regulatory Commission. Development of this multitiered collection of interrelated strategic plans is of utmost importance and is indispensable for DOE's effective management of SNF, high-level and transuranic wastes, and excess enriched uranium and transuranic materials. NEED FOR DEFINITION OF PRODUCTS AND TECHNOLOGY USE Before the DOE makes a final decision about widespread implementation of the ANL electrometallurgical technology for treating DOE SNF, it is essential that the DOE determine how the electrometallurgical technology and other treatment technologies fit into its overall strategy for disposal of SNF and the closely related strategy for management of high-level and transuranic wastes. A meaningful comparison of the electrometallurgical process with alternative processes for converting SNF to acceptable disposal forms would include consideration of Desired products, Criteria for allowable disposal volumes and disposal forms, 4   Performance Assessment of the Direct Disposal in Unsaturated Tuff of Spent Nuclear Fuel and High-Level Waste Owned by U.S. Department of Energy, 3 volumes, Rob P. Rechard, editor, Sandia National Laboratories report SAND 94-2563, March, 1995. 5   See, e.g., National Academy of Sciences, Management and Disposition of Excess Weapons Plutonium, National Academy Press, Washington, D.C., 1994.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL Overall cost and schedule considerations for SNF processing, and Schedule implications of the time needed for the development and demonstration of improved processes. Adequate definition of desired products is necessary for establishing the required operating mode for the electrometallurgical process. Otherwise it is not known whether it would be necessary to produce highly purified uranium or plutonium as is possible with alternatives such as Purex. The cost-effectiveness of Purex and other alternative processes might be improved if the goal were production of waste forms that contain only partially separated uranium, plutonium, fission products, and transuranic elements originally present in the SNF, as is the case with the electrometallurgical process. Even during the short duration of this study, ANL has refined plans for both the process and the resulting products in response to interim information on what would constitute acceptable final waste forms. Meaningful process and cost comparisons for converting SNF to acceptable forms for disposition are not possible without defined disposition end-points and schedules for SNF conversion and disposition. With regard to development schedules, several alternative processes for SNF conversion are available or under development in addition to the electrometallurgical process. None of them needs to be implemented immediately, but they all require further research, development, and demonstration before they would be available on a production scale. Comprehensive studies comparing the benefits of near-term SNF conversion with those of extended, improved interim SNF storage would allow DOE to determine whether the required time is available for further development of improved processes for converting SNF to acceptable waste forms. SCHEDULE CONSIDERATIONS FOR DISPOSAL OF N-REACTOR FUEL Plans for dealing with the problems posed by contamination of Hanford 's K-basins where the N-reactor fuel is stored call for initiating encapsulation of the K-basin East sludge by June 30, 1996, with completion of the sludge and fuel encapsulation in both the east and west basins by the end of 2002. These targets appear to be extraordinarily ambitious when it is recognized that an interim-action environmental impact statement is required and that a facility must be constructed or modified and approved operationally before the work is initiated. The physical and chemical condition of some of the N-reactor fuel is poorly understood, as is the nature of the sludge. It would be necessary to adequately determine the present condition of the fuel and the sludge before serious plans for processing them via the electrometallurgical process could be developed to a significant level of detail. Even for seemingly intact fuel, careful inspection or oxide-reduction head-end treatment would be necessary for all material being fed into the electrorefiner to be certain that the feed did not contain significant amounts of oxides. For the oxidized N-reactor fuel, head-end treatment would be needed for oxide reduction and mechanical handling of broken and non-uniform fuel assemblies. Current plans at Hanford6 call for construction of a staging and storing facility (preferably in the “200” area where much of the highly radioactive processing work was done) and transferring the K-basins fuel there by the year 2000. An adjoining fuel stabilization facility would be constructed to “stabilize” the fuel 6   Briefing to committee from Grant Culley, Westinghouse Hanford Co., March 24, 1995 (see Appendix B).

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL so that it would be suitable for dry storage. Current plans call for completing the stabilization by the year 2006, after which the fuel and sludge would be returned to the staging and storage facility to be stored for up to 40 years. Plans for the staging and storage facility call for it to be designed to accommodate the remainder of the SNF at Hanford. Presumably, if the decision were made to use the electrometallurgical process for treating N-reactor fuel, the processing facility and equipment could be incorporated into the fuel stabilization facility. The committee believes that it is unlikely that the above schedules will be met in view of the current climate of budgetary constraint, the absence of crucial information on fuel and sludge properties, and the need for construction of major facilities. If the schedules are prolonged, maintaining the capability of using the electrometallurgical technology for treatment of N-reactor fuel would require maintenance and support of ANL's expertise for an indefinite but long period while the retrieval, stabilization, and storage of the N-reactor fuel took place. WASTE FORM QUALIFICATION CONSIDERATIONS FOR THE ELECTROMETALLURGICAL PROCESS The major limitation of the electrometallurgical process (whether applied to N-reactor fuels or other SNF) is its present inability to produce waste forms with behavior that is well understood (in comparison, for example, to the degree to which glass forms have been studied). According to the developers of the electrometallurgical process, the “reactive” fission products are to be incorporated in a zeolite matrix that may be further treated to enhance its stability and durability. The remainder of the fission products are to be incorporated in a metal matrix of zirconium or iron or a blend of both. According to ANL's proposal, the uranium and other actinides, including plutonium, are to go to “interim storage.” The time and cost for qualifying any new waste form are expected to be large, and the qualification process is fraught with technical and “political” pitfalls. To date, no waste forms have been licensed or qualified for geologic disposal, although a large body of knowledge has been accumulated on borosilicate glass, which is the leading candidate waste form for high-level waste and is favored over other waste form types. The unspecified nature of “interim storage” for the actinides (including plutonium) appears to be a major unresolved factor. The committee recommends that the DOE include in its evaluations of the electrometallurgical process the added costs and delays expected for the development of new waste forms, especially if there are other waste management approaches that might involve lesser hurdles. PROLIFERATION RESISTANCE CONSIDERATIONS Although the developers of the electrometallurgical technique argue that the technology is proliferation resistant, any SNF processing approach that is capable of separating fissionable materials from associated fission products and transuranic elements could be redirected to produce material with nuclear detonation capability. The committee believes, therefore, that proliferation aspects of the electrometallurgical process and its processing alternatives are not a determining factor for differentiating among these processes. The electrometallurgical process could be operated to produce a relatively poor separation of spent fuel into fission products, actinides including plutonium, and uranium. The electrometallurgical technology is not as effective as some other processing alternatives in accomplishing

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL these separations. The high radioactivity of the TRU fraction containing the plutonium would reduce the likelihood of theft of this material. Demonstration of the process could, however, add to the risk that a nation intent on weapons production might consider adapting this technology for possible production of fissile material, although such material would be of poor quality for a weapon. A full review of the proliferation risks associated with closely related processing techniques proposed for the Integral Fast Reactor was published recently. 7 That report concluded that “the intrinsic radioactivity of the recycle plutonium product and the requirement of remote recycle operations in inert-atmosphere hot cells are favorable safeguard factors. . . [but] inspectability and material accountability for verification purposes are relatively more difficult” than for a Purex plant. INFLUENCES OF THE EBR-II DEMONSTRATION ON ELECTROMETALLURGICAL PROCESS DEVELOPMENT The DOE's commitment to process the spent fuel from EBR-II will allow development and demonstration of the electrometallurgical process to continue during the several years required for processing the EBR-II driver and blanket fuels. In particular, this commitment will lead to the development of an electrorefiner with 20 times the throughput of the existing one in order to facilitate processing of the EBR-II blanket fuel. Processing of the EBR-II fuel will not, however, require development of the proposed steps for head-end reduction of oxide fuels using metallic lithium or for the regeneration of recycled metallic lithium via indirect electrolytic reduction of the resulting lithium oxide. It appears that several years will elapse before DOE would proceed with processing other SNF to which the electrometallurgical process could potentially be applicable. It also is unclear whether oxide-based SNF will require processing prior to ultimate disposal.8 Consequently, continued near-term development of process steps necessary for processing oxide fuels may not be justified. The current ANL staff (both at ANL-East and ANL-West) represents a unique collection of R&D capability and possesses an in-depth understanding of the electrometallurgical process. Reestablishment of this capability would entail great expense and time if the proposed development effort were not continued but restarted after a reasoned later decision to apply the electrometallurgical process to SNF other than the EBR-II driver and blanket fuel. To enable rational decision making regarding continued R&D on the electrometallurgical process and other promising SNF treatment alternatives, the DOE needs a multitiered comprehensive planning and policy strategy. TECHNOLOGY DEVELOPMENT FOR DOE SPENT NUCLEAR FUEL The DOE Implementation Plan developed in response to the Defense Nuclear Facilities Safety Board Recommendation 94-1 states that a research committee, to have been established by March 15, 1995, would be responsible to the DOE nuclear materials stabilization task group. The research committee's 7   R.G. Wymer et al., An Assessment of the Proliferation Potential and International Implications of the Integral Fast Reactor, Martin Marietta Energy Systems report K/ITP-511, Oak Ridge, Tenn., May, 1992. 8   The committee notes that the oxide reduction process could also be used to treat commercial LWR spent fuels by the electrometallurgical technology. This would, of course, have major policy implications in the United States.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL responsibilities would include developing an R&D plan to address the short- and long-term needs for the nuclear materials stabilization task group that integrates efforts carried out within a large number of DOE organizations. The DOE should critically evaluate through that research committee the need for the electrometallurgical process and alternative processes for converting SNF and other nuclear materials to forms suitable for disposal.

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL 6 FINDINGS, CONCLUSIONS, AND RECOMMENDATIONS The committee's charge required it to evaluate the metallurgical process in terms of technical feasibility, cost-effectiveness, suitability of the metallic waste form for long-term storage or geologic disposal, and nonproliferation implications. The committee's observations on the technical feasibility of the electrometallurgical process are included in Chapter 2 (pp. 11-12), which describes what ANL has accomplished and the R &D effort that must still be carried out. The possible applicability of the electrometallurgical process for DOE SNF is discussed in Chapter 3 (pp. 18-19). Issues of cost-effectiveness are discussed in Chapter 3(pp. 19-21), but the committee found that available data were insufficient to make meaningful comparisons with alternative approaches. The cladding-metal waste form (the “metallic waste form” denoted in the charge) is discussed in Chapter 2 (p. 12) and Chapter 4 (pp. 25-26); the performance of the cladding-metal waste form has had only preliminary study, and so it was not possible for the committee to fully evaluate its suitability for long-term storage. Other effluent streams are discussed in Chapter 4 and in Chapter 5 (p. 30). Finally, the implications of proliferation issues are addressed in Chapter 5 (pp. 30-31). In its interim report (see Appendix A) the committee observed that the electrometallurgical technique is not a new technology. The chemical feasibility of the technique is well established except with respect to the proposed zeolite-based steps for waste treatment. Accordingly, the amount of research necessary for understanding the underlying chemistry and physics of the electrometallurgical technique is limited. Indeed, the ANL proposal (see Appendix A) addresses a “Proposed Development Program” (emphasis added). A substantial development and demonstration program is still necessary to show whether the electrometallurgical technique can be a viable option that the DOE could employ, if it chooses to do so, to treat a portion of its SNF. The production of suitable waste forms has not been demonstrated and poses a noteworthy challenge. Within the context of the problem of managing DOE SNF, a development program should be directed toward, and limited to, demonstration of those components of the technology that could be used to satisfy the reasonably foreseeable needs and schedules of the DOE. For example, if the DOE determines that there is no current or reasonably foreseeable need in the near term for the ANL technique to be used to treat spent oxide or damaged N-reactor fuel, development activities proposed for SNF in the oxide form do not appear justified. Accordingly, the DOE should determine how this technology and other options fit into its overall strategy for disposal of SNF. Insofar as such a determination specifies the SNF to be considered for electrometallurgical processing, the physical and chemical properties of that SNF could significantly affect the goals of ANL's development program. An electrometallurgical development program should address specific hardware performance, the scale-up of apparatus and systems from experimental and research prototypes to practical operating sizes, and overall system effectiveness. Since the electrorefining part of the process requires a metallic feed, the head-end or pre-electrorefiner operations must be tailored to convert spent fuels of various compositions and conditions to the metallic form that the electrorefiner can accommodate. Additionally, a development program should demonstrate the successful remote handling of materials and components and remote maintenance, all leading to the effectiveness of the entire sequence of hot-cell operations. Since the process steps are for the most part sequential, each is dependent on the successful operation of previous steps and it is particularly important that the reliability of individual unit operations be

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AN ASSESSMENT OF CONTINUED R&D INTO AN ELECTROMETALLURGICAL APPROACH FOR TREATING DOE SPENT NUCLEAR FUEL successfully shown. The issue of reliability will be addressed and evaluated during the treatment of EBR-II spent fuel and blanket assemblies. The DOE intends to demonstrate some aspects of the technical viability of the electrometallurgical processing technology through its successful application to the processing of EBR-II SNF. The EBR-II processing plan includes the following process flow steps: Dismantling of spent fuel assemblies, Chopping of fuel pins, Electrorefiner processing, Cathode processing, Casting of ingots Storage of uranium and interim TRU products Waste treatment and production of waste forms, Metal waste forms Mineral waste form Recycle of process reagents. The two major milestones scheduled through the spring of 1996 are treatment of the first four driver assemblies (June 1995) and start of the production of a sample metal waste form (March 1996). The first blanket-assembly processing campaign is currently scheduled for completion in April 1998. DOE oversight of the progress of the planned EBR-II program in the next and subsequent years will serve to evaluate the effectiveness of the electrometallurgical process. Any delay in the achievement of specified milestones may have an adverse effect on the ability of the DOE to include this technology as an option in its selection of technologies to be applied to the treatment of SNF. This decision is expected by October 1998. CRITERIA FOR SUCCESSFUL PROCESS DEMONSTRATION DURING THE TREATMENT OF EBR-II SNF Monitoring and oversight of the progress of the EBR-II spent fuel program are critical to assessing the feasibility of the electrometallurgical technique. (However, the committee was not asked to, nor did it, investigate in depth this phase of the overall electrometallurgical treatment program.) To assist the DOE in evaluating the progress and success of this project, the committee recommends the following accomplishments as a minimum definition of “successful application ”: Demonstration of batch operation of an electrorefiner and a cathode processor with a capacity of approximately 200 kg/day of radioactive EBR-II spent fuel without failure for about 30 days.