SUMMARY OF INTERNATIONAL SEPARATIONS AND TRANSMUTATION ACTIVITIES
During the last few years, there has been a substantial increase in the number of countries and international organizations undertaking programs related to investigation of one or more aspects of separations and transmutation (S&T). The purpose of this appendix is to provide a summary of the most significant activities. Except where specifically noted, the information presented in this section is based on a report prepared by the Electric Power Research Institute and its contractors (EPRI, 1991) and papers presented at the National Research Council Symposium of Separations Technology and Transmutation Systems (National Research Council, 1992). For recent information on technological details of international S&T activities, the reader is referred to (OECD/NEA 1990, 1992).
The section in which a particular activity is discussed is somewhat arbitrary at times. The complex web of collaborative international activities and organizations makes definitive assignment of activities to specific installations or nations very difficult or impossible.
PROGRAMS OF INDIVIDUAL NATIONS
China (OECD/NEA, 1990)
China, though not in possession of any operating nuclear power reactors, has been reprocessing spent fuels from its other reactors since the 1960s. During this time, three processes have been developed to separate actinides from high-level waste (HLW): reverse TALSPEAK, a process in which the Am(III) + Ln(III) elements are extracted in an organic phase by di (2-ethylhexyl) phosphoric acid (HDEHP). Research activities to optimize the reverse TALSPEAK and DHDECMP process are ongoing, along with work on separation of platinum-group metals and cleanup of degraded solvents. Hot demonstration of actinide extraction is planned. Transmutation is not yet being studied.
Czech and Slovak Federal Republic (OECD/NEA, 1990)
The Institute of Nuclear Research in Rez, Czech and Slovak Federal Republic (CSFR) has synthesized a new extractant, cobalt dicarbollide, under the sponsorship of the Radium Institute in Leningrad. This extractant shows promise for separation of radiocesium and, when mixed with polyethylene glycol, for separating radiostrontium from highly acid solutions. Laboratory work has been conducted in the CSFR, and hot testing at the Radium Institute. The
work is still in the research stage because of difficulties with low product concentrations, the use of nitrobenzene as a diluent, and the high cost of the extractant. Work is currently suspended because of the recent political change in the former Soviet Union.
France is committed to nuclear fuel reprocessing and actinide recycle as a matter of national policy, and these activities are presently practiced domestically and as part of international commerce. During the last few years, France has initiated work to establish a geologic repository for the HLW and other long-lived wastes resulting from their nuclear activities. Recognizing the controversial nature of such facilities, the French legislature adopted a long-term approach to repository development. In addition, specific legislation was passed in 1991 that, among other things, called for continuing study of S&T with a final assessment to be provided within 15 years.
The French have been relatively explicit about their rationale for pursuing S&T (National Research Council, 1991). They currently believe that the reduction in long-term repository risk is not large enough to justify S&T, primarily because the absolute risk values are below levels deemed acceptable. However, they acknowledge sufficient uncertainties in the risk calculations (e.g., concerning actinide solubility limits, colloids, and complexes) that continued examination of S&T is warranted.
The French program to investigate S&T is called SPIN. It comprises two major subparts: PURETEX and ACTINEX. The former is a shorter-term program to increase the recovery of plutonium, separate and recycle neptunium, and reduce the amounts of intermediate-level waste (roughly equivalent to transuranic [TRU] waste in the United States), primarily within existing production facilities. The latter is a longer-term effort involving enhanced separation of all TRU elements, separation of long-lived fission products, and recycle of the TRUs and fission products to transmutation devices. This effort would involve new facilities.
Separation studies are heavily focused on aqueous systems, although nonaqueous processes are being considered. The behavior and control of neptunium in PUREX processing is being closely studied for near-term applications. Of particular interest, the French are examining the use of diamides as alternatives to the reagents employed in the U.S.-developed TRUEX process (i.e., carbomoyl methyl phosphine oxide [CMPO]). Nitrogen and sulfur donors are being studied for the purpose of separating Am(III) from lanthanides, a traditionally difficult separation. Electro-oxidation of actinides to accomplish this separation is also being considered.
Transmutation efforts are focused on thermal and fast nuclear reactors, although some consideration is to be given to accelerators. Some fundamental physics data is being obtained (e.g., actinide cross sections), and test pins are being irradiated in various French reactors.
The budget for SPIN is approximately $600 million over 15 years, which includes funding for new research and development facilities at Marcoule. The 1992 budget was about $17 million. In both cases, there is somewhat of an emphasis on PURETEX. The effort for 1991 was 20 person-years. This may expand to 40 to 50 person-years within a 5-year plan.
Germany is not now reprocessing fuel and has no immediate prospects for doing so. However, study of reprocessing and S&T continues for the future. Of particular interest is study of a single-cycle aqueous process for reprocessing spent fuels. These activities are centered at Karlsruhe, at the Institute of Nuclear Research.
India (OECD/NEA, 1990)
India is conducting studies of the nuclear physics aspects of the minor actinides that are directed at processing and compiling a database that would support accurate reactor-physics calculations.
Italy (OECD/NEA, 1990)
A number of Italian radiochemical facilities are in the process of being decommissioned due to budget cuts. The Italians, in a program partially funded by the Commission of the European Communities (CEC), are pursuing separations technology to enable them to better manage their wastes. Multiple partitioning processes for actinides, technetium, strontium, and cesium from various waste streams have been identified and tested on simulated wastes for the purpose of identifying the preferred processes. The next phase calls for hot continuous testing of the preferred process in a small pilot plant at the Joint Research Center at Ispra, which is scheduled to be completed in 1995.
Transmutation studies have been historically performed on thermal and fast neutron reactors. More recently, the Italians have performed confirmatory reactor physics calculations on the aqueous accelerator transmutation flow of wastes (ATW) and compared them with Los Alamos National Laboratory (LANL) calculations (OECD/NEA, 1992), with some significant differences being noted.
The Japanese are committed to reprocessing as a matter of national policy and have the most comprehensive and organized S&T program of any nation or organization. Japan's Option Making Extra Gains from Actinides and Fission Products (OMEGA) program—started in 1985 and formalized in 1987—is a comprehensive, long-term effort involving data acquisition and evaluation, study of partitioning schemes, and transmutation of nuclides in reactors or by using accelerators. OMEGA funding is nominally about $10 million per year, although it is not clear how much ''work in kind" is being provided by the participating organizations. The OMEGA program is only summarized briefly here. A paper given at the Separations and Transmutation
Systems (STATS) Symposium (National Research Council, 1992) provides an excellent, detailed overview of the OMEGA program.
The Japanese program involves multiple organizations, including the Japan Atomic Energy Research Institute, the Power Reactor and Nuclear Fuel Development Corporation, and the Central Research Institute of Electric Power Industry.
Transmutation studies are directed at the use as a transmutation device of metal-and oxide-fueled fast reactors (liquid-metal reactors [LMRs]), proton accelerators (i.e., spallation neutrons), or electron accelerators (i.e., photons). The predominant emphasis is on oxide systems as fuel forms, but metal fuels and pyrochemical processing are also being considered.
Partitioning studies involve significant efforts on both aqueous and nonaqueous technologies, although the former are dominant. Partitioning studies are focused on recovery and recycle of long-lived toxic radionuclides as well as recovery and reuse of useful (e.g., noble) metals.
The Japanese appear to be approaching this issue from a collaborative standpoint, having established working agreements with multiple countries. Within the United States, they are known to have working arrangements with Oak Ridge National Laboratory, Battelle, Argonne National Laboratory (ANL), and Rockwell International.
Korea (OECD/NEA, 1990)
The Republic of Korea has embarked on a three-phase, 10-year program to investigate S&T technologies and selected isotope separations related to waste management. A variety of separations technologies are being examined for separating actinides and selected fission products from wastes. The initial step involves literature surveys and laboratory studies to elucidate the nature of the radioelements of interest, which are scheduled to be completed by 1993. This will be followed by cold laboratory studies through 1996 and the specification, design, and operation of a pilot-scale process by 2000.
The separation of long-lived 107Pd from radiopalladium using laser isotope separation techniques is being studied. This work is currently in the basic research stage.
Transmutation of actinides using proton accelerators has temporarily been selected as the preferred method, and this technology is being studied. Tests are expected to be conducted collaboratively with other nations.
The Dutch government has requested that the Netherlands Energy Research Foundation study actinide transmutation. The foundation is currently studying the use of thermal reactors, fast reactors, and accelerators in this application, especially with regard to the nuclear physics of the transmutation process.
Russia has a long-standing and continuing interest in multiple aspects of S&T going back decades to when cesium and strontium were separated from defense HLW. Research and development activities continue concerning transmutation studies, nuclear physics (cross section libraries), partitioning technology (aqueous and nonaqueous), actinide-recycle fuel fabrication, special actinide burning cores for fast breeder reactors, use of military/defense reactor systems (e.g., lead/bismuth-cooled reactors) for transmutation, and special burner reactors. Extensive work has been undertaken on accelerators for a variety of applications, and there is apparent interest in their application to transmutation systems.
A modest effort is underway in the Chalmers University of Technology (CTH), Götenborg, to examine aspects of S&T. Some transmutation calculations have been performed. Experimental and calculational study of actinide partitioning has been performed on cold and hot solutions based on the use of tributyl phosphate and di (2-ethyl hexyl) phosphoric acid extractants in what is designated the "CTH Process."
The Paul Scherrer Institute has conducted calculational studies related to actinide transmutation via spallation. Irradiation of small samples is proposed to validate the calculations.
The United Kingdom view of S&T is that it may be costly and has not been shown to be desirable. The United Kingdom is continuing to monitor and evaluate worldwide developments related to S&T with the expectation that such processes will prove to be undesirable after further evaluation.
As is France, the United Kingdom is dedicated to fuel reprocessing as a matter of national policy and international commerce. The United Kingdom approach is to perform research and development to improve aqueous reprocessing which in turn will improve its cost-effectiveness of the reprocessing. The cost-effectiveness is to be balanced against increased risk by using a philosophy of "best available technology not entailing excessive cost."
Research and development efforts by the British that may relate to S&T include the development of technologies to sharply reduce the cost of reprocessing. These include adoption of centrifugal contractors; study of technetium behavior during aqueous processing to prevent it from partially following product streams; and consideration of "radical PUREX," in which the
entire fuel pin is dissolved (to reduce head-end costs), a simplified (perhaps one-cycle) extraction flowsheet is used, and alternative product conversion technologies (e.g., thermal denitration) are employed.
The United States is presently committed to a once-through fuel cycle. However, a number of organizations are undertaking studies related to S&T. These studies are largely the result of initiatives by the individual organizations. An integrated governmental program regarding S&T is absent.
An advanced liquid-metal reactor program (ANL and General Electric) is developing sodium-cooled fast reactors, primarily for use in electricity production. These devices have also been proposed as actinide transmutation devices. Essentially the entire focus is on metal fuels and pyrochemical reprocessing of these fuels. However, oxide fuels and aqueous reprocessing is maintained as a back-up and for potential use in international applications.
LANL has proposed a fluid-fuel, accelerator-based system for use in a number of potentially synergistic applications. These include TRU transmutation, long-lived fission-product transmutation, destruction of plutonium from dismantled nuclear weapons, and production of tritium. The systems involve subcritical transmutation via proton-generated spallation neutrons. Aqueous and molten-salt systems are being examined.
Westinghouse Hanford Co. has put forth the Clean Use of Reactor Energy (CURE) concept regarding S&T. This is more a systems concept for S&T than a specific transmutation device or partitioning technology. It advocates the complementary use of various technologies to achieve S&T, and is primarily based on aqueous/oxide systems.
Brookhaven National Laboratory is pursuing two technologies related to S&T. The first involves the use of accelerators to transmute actinides. In this case, the protons impinge directly on the targets (in the form of standard fuel assemblies), and neutron spallation is secondary. The second technology involves adaptation of a high-flux thermal reactor designed for space applications. This device is based on high-temperature gas-cooled reactor (HTGR) fuel technology and has a high specific power (i.e., transmutation rate) during the in-core period.
The Commission of the European Communities (CEC)
The CEC operates four joint research centers with funding from its member states: Geel (Belgium), Ispra (Italy), Karlsruhe (Germany)—also known as the Institute for Transuranium Elements—and Petten (Netherlands). The Karlsruhe and Ispra sites are the most heavily involved in S&T activities. The CEC is studying various aspects of S&T at the request of the Parliament of the European Community. The work is supported in part by the member states of the
European Community and in part under cost-sharing arrangements with other organizations or states.
Activities at Karlsruhe include:
basic studies of actinide properties (e.g., single crystals) and californium neutron source manufacture;
manufacture and postirradiation examination of targets inserted into existing LMRs (e.g., Phénix, Dounrey);
minor-actinide-fueled LMR core design and safety analysis; and
study of zirconium-based metal alloy fuels, especially related to the maximum minor actinide content thereof.
Study of S&T has been conducted in Italy under the joint sponsorship of the CEC and the Italian government, and more activities are planned for the future. These are described under the section on Italy above.
International Atomic Energy Agency (IAEA) of the United Nations
The IAEA is primarily a coordination agency, which focuses on the nations that are not part of the Organization of Economic Cooperation and Development (OECD) (i.e., the less industrialized ones) and represents their views in various venues.
A study conducted in the 1970s by the IAEA concluded that there is little incentive to reduce long-term hazards of actinides and fission products by S&T. The incremental cost of introducing S&T was considered unduly high in relation to the prospective benefits. After a period of dormancy—there is now a renewed interest in the subject in some countries—an advisory group meeting was held in 1991 to discuss S&T. The group recommended setting up a scientific advisory body to coordinate the activities of those countries that are a part of the Nuclear Energy Agency of the OECD (OECD/NEA) and those that are not OECD/NEA members. A 5-year program consisting of advisory and technical committee meetings and coordinated research programs has been formulated. IAEA considers S&T as a futuristic option and that S&T cannot avoid the need for long-term, deep geological disposal (IAEA, 1991).
The NEA is the arm of the OECD that addresses nuclear issues. The OECD has 23 nations as members, which is larger than the CEC but includes its 12 member nations. The standing committees of the NEA (i.e., development, nuclear science, radioactive waste management) all conduct technical studies using contributions from the member nations (general and proposal-specific) in conjunction with the contribution of work-in-kind from interested nations. The NEA has recognized that S&T is not an alternative to a repository but is a technology worthy of further study for potential longer-term application.
The NEA is actively supporting a program of informal S&T information-exchange meetings initiated by Japan, and additional financial support has been provide by Japan. Fourteen countries and the CEC have identified liaison officers for the information exchange. At the first meeting held at Mito, Japan (OECD/NEA, 1990), the participants concluded that there were benefits to wider international cooperation regarding S&T. Meetings of specialists on specific topics within the S&T rubric have been organized at Karlsruhe, Germany (on fuels and targets), Mito, Japan (on partitioning technology), and the Paul Scherrer Institute in Switzerland (on accelerator-based transmutation).
In addition, the OECD supports other studies that are relevant to S&T. These generally relate to the economic and risk aspects of nuclear fuel cycles and competing energy-production technologies. These aspects are important components of the systems studies necessary to evaluate the S&T concept and alternatives within it.
S&T is being studied to varying degrees by most major nuclear nations and international organizations. Japan, France, and the United States are putting considerable efforts into S&T. A number of other nations have more modest efforts. The notable exception is the United Kingdom, which has adopted a "wait and see" posture.
In all cases, it is clear that S&T is not viewed as a replacement for a repository. However, there is some observed correlation between the current difficulty in establishing a repository (technical or institutional) and the degree of interest in S&T. For Japan, the interest may also be due to a lack of uranium and other energy resources.
In France and the United Kingdom, the distinction between separations and "process improvement" is becoming blurred. Activities designated as separations are resulting in process improvements, and many aspects of process improvement (or evolution) would facilitate separations.
No nation has committed itself to deploy S&T technology, although the French are installing provisions to recycle neptunium and have a program with a near-term focus to improve operations in their existing reprocessing plants. A few nations are committed to long-term programs to further develop the technology and make decisions in 10 years or so. The programs of most nations are not committed to a specific agenda, with the timing and nature of decisions to be determined.
The emphasis on the relatively more difficult separations aspects (as compared with transmutation) has increased from previous episodes of significant work on S&T. Relatively little work is evident on the fabrication aspects of fuels with increased concentrations of minor actinides or long-lived fission products.
Most programs are in the relatively inexpensive research and development stage. The higher costs attendant to radioactive work at larger scales has engendered a general desire for international collaboration that is much broader than in previous episodes of studying S&T.
With the exception of that of the United States, most separations research and development is focused on aqueous processes. Transmutation is mostly focused on a variety of fission reactors, although there are significant efforts on accelerator-based transmutation.
Electric Power Research Institute (EPRI). 1991. International Programs Related to the Transmutation of Transuranics. EPRI NP-7265. Palo Alto, Calif.: EPRI.
International Atomic Energy Agency (IAEA). 1991. Communication from Director, Nuclear Fuel Cycle Division, Dec. 4, 1991, enclosing minutes of Advisory Group meeting October, 21-24.
National Research Council. 1991. Separation and Transmutation of Actinides. Presentation by the Commissariat à l'Energie Atomique to the Board on Radioactive Waste Management. March 18.
National Research Council. 1992. Symposium on Separations Technology and Transmutation Systems. January 13-14.
Organization for Economic Cooperation and Development/Nuclear Energy Agency (OECD/NEA). 1990. Proceedings of the Information Exchange Meeting on Actinide and Fission Product Separation and Transmutation, Mito City, Japan. November 6-8.
Organization for Economic Cooperation and Development/Nuclear Energy Agency (OECD/NEA). 1992. International Information Exchange Program on Actinide and Fission Product Separation and Transmutation, Argonne National Laboratory. November 11-13.