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Nuclear Wastes: Technologies for Separations and Transmutation CHAPTER SIX— ANALYSIS OF THE ISSUES IMPACT OF S&T ON WASTE REPOSITORY All of the proposed Separation and Transmutation (S&T) systems have the potential to affect the design and long-term performance of nuclear waste repositories. Since these systems would require reprocessing of spent fuel, they would allow the separation of transuranics (TRUs) and selected fission products from spent fuel. The waste going to repositories would have less thermal power, would contain a reduced quantity of certain isotopes, and could be incorporated in waste forms with good integrity. These separated species would then be recycled in an ongoing fuel cycle of additional reactors and maintained at constant inventory per reactor until ultimately reduced in quantity in a possible phase-out of nuclear power. The claims of the possible effects of S&T on the first repository in the United States have ranged from eliminating the need for a repository to improving performance so as to provide a sounder technical basis for licensing. It has been proposed further that reducing the decay heat of the waste would permit the repository's capacity to be increased, thereby eliminating or postponing the need for a second repository. Evaluation of Possible Repository Releases A performance assessment of nuclear waste repositories relies on evaluation of possible future conditions and events that might allow radioactivity to be released. Two general areas are typically addressed: (1) transport of radioactivity by fluid flow (water or air) into the human environment, and (2) disruptive events and inadvertent human intrusion that cause a portion of the repository contents to be directly transported to the surface or injected into the groundwater system. A limited number of performance assessments have been performed for repositories in the United States, for example, evaluations for the Waste Isolation Pilot Plant (WIPP) (Sandia National Laboratories, 1992). These assessments indicate its general compliance with the original EPA containment standard. For the WIPP, human intrusion would provide the primary mechanism for any appreciable radiation release to the environment. No direct assessments of the risk of radiation exposure to individuals have been made for human intrusion scenarios by current repository projects in the United States. They Yucca Mountain project has completed an initial set of calculations (Wilson et al., 1994) that will be further refined as data are obtained from site characterizations. The calculations show that the probabilistic estimates of release are within the limits of the EPA standard and also that the primary concern is the gaseous transport of 14C to the surface. A larger set of calculations that have been performed evaluate the long-term release of radioactivity as well as the consequence and risk of individual exposure for other repository settings. Many of the concepts relating repository performance to transmutation have been addressed in the report by Ramspott et al. (1992). In general, all calculations made to date, regardless of the basis for the evaluation (i.e., release to the environment or individual dose) indicate the following: The release of radioactivity to the environment via groundwater pathways is dominated by soluble, nonsorbing, long-lived radionuclides. The dominant products released via human intrusion or disruptive events, which can occur earlier in the life of the repository and extract radioactivity directly from the waste package, would be TRUs, such as plutonium and americium. In the case of Yucca Mountain, gaseous transport of
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Nuclear Wastes: Technologies for Separations and Transmutation 14C could be the major contributor to predicted releases above the limits of the original EPA standard.1 Effects of S&T Processes The S&T concepts with significant thermal-flux levels (accelerator transmutation of waste [ATW] and light-water reactors [LWR]) have the potential to reduce the mass of fission products in the reactors and repository wastes. In addition, the processes consume fissionable TRUs as fuel. Consequently, these concepts would reduce the risks associated with releases due to both human intrusion and fluid transport provided no additional fission products from external sources are laded into the repository. In the LWR case, reprocessing of spent fuel and transmutation of plutonium through recycling would ultimately yield increasing amounts of americium and curium. Their ultimate disposition would limit S&T benefits related to human intrusion releases. The fast fluxes in the advanced liquid-metal reactor systems would primarily affect the magnitude of and consequently, the hazards related to the TRUs. Since the separated TRUs would remain in the operating fuel cycle, potential releases from human intrusion could be reduced. Fission products would not be reduced significantly, and fluid-transport release would not be directly affected. However, the advanced liquid-metal reactor (ALMR) program emphasizes the benefit of reduced heat-generation risks per unit of electrical energy predicted, allowing more fission products to be loaded into the repository. This greater concentration would eventually increase the figure for predicted individual dose related to aqueous-transport release. The ultimate composition and character of the waste delivered to the repository will be determined both by the types of transmutation devices and by the reprocessing separations and vitrification operations—more americium and curium and less iodine and technitium will result from a thermal spectrum, for example, from transmutation. All S&T concepts provide the potential for reducing the quantity of some radionuclides in the waste product, thereby allowing it to be retained on the earth's surface. Reprocessing and inclusion of the products in a higher-integrity waste form without transmutation would allow some advantages in reducing the adverse impacts of the source term for both human intrusion and fluid-transport scenarios. Reprocessing also provides a significant advantage in that it can separate much of the 14C from spent fuel. This allows the 14C to be released to the atmosphere within current operational standards, stored on the surface for long periods, or converted to a nongaseous form for geologic disposal. While such dispositions would result in a marked improvement in predicted performance for Yucca Mountain, 14C is probably best addressed by more careful examination to provide consistent disposal standards. It would seem unreasonable at this point to allow the performance of repository to be based on a long-term release of 14C over thousands of years, when by simply addressing a different set of operating release standards, the same amount of 14C could be released into the atmosphere without violating current regulations. Finally, all S&T concepts will yield reprocessing products and secondary waste streams that could easily contain sufficient radioactivity to require disposal in a repository. It is unlikely that either the primary or secondary waste products could be kept below the 100-nCi/gm level for TRU wastes, which is the threshold level that differentiates TRU waste from low-level waste. Elimination of all TRUs from HLW would reduce heat generation relative to spent fuel. At 10 years after discharge the TRUs in the spent fuel contribute 20% of the heat generation rate at that time, 60% at 100 years, and 99% at 300 years.2 These percentages are also the percentage reduction in thermal power at those times if TRUs are all removed (see Appendix G for details). If this reduction in thermal power is coupled with a sequential waste emplacement approach, significant gains in repository capacity (4 to 5 times current capacity) could be achieved. (This equivalent would, however, eventually increase the predicted individual dose from aqueous transport from the first repository.) It should be noted that the current limit for Yucca Mountain (70,000 MTU) is less than the discharge expected from the existing LWRs (approximately 90,000 MTU) during their lifetimes. Yucca Mountain's capacity could be increased beyond the current level by one of the following: (1) using higher-density emplacement schemes or (2) more fully utilizing planned underground areas. In considering a thermal design strategy for the Yucca Mountain repository the characteristics of the unsaturated zone and the long-term heat generation by actinides in spent fuel must be considered. Thus a thermal design strategy for repositories in other rock types with other waste forms could be substantially different. The wastes for permanent disposal will have varying concentrations of fissile materials depending on what process generates them. In most cases, the dominant fissile species will be 239Pu and 235U. Under some conditions, it may be possible for the waste deposit to reach criticality.3 1 In general, 14C will, if the principal transport is by water, influence the residual radiotoxicity if the pH of the formation is not alkaline (pH 9). In that case, CO3 and HCO3 migration will occur. In the case of alk aline formulation, presence of large CaCO3 concentration (e.g., in clay) is a geological buffer against CO3 and HCO3 diffusion. 2 The integrated heat release will depend on the type of waste (reprocessed waste). The impacts on the repository are different for different repository types beyond the Yucca Mountain repository with its characteristic unsaturated zone. 3 The possibility of autocatalytic criticality with some energy release has been raised recently (Bowman et al., 1994).
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Nuclear Wastes: Technologies for Separations and Transmutation Avoidance of criticality can usually be achieved by adjusting the composition of the waste, size, separation of the waste canisters, or the type of overpack used. Because criticality calculations depend on the specific characteristics of the repository and waste, this issue was not dealt with further in this study. Impact on the First Repository Full implementation of an S&T system would provide a durable waste form depleted in TRUs and/or fission products (see Appendix G). Further, it could eliminate 14C as a major contributor to predicted releases above EPA limits and could reduce heat loadings significantly after the second hundred years. Furthermore, the lower concentrations of key soluble radionuclides in the waste would result in reduced release to the environment over the long term. Even though the goal of transmuting all waste to Class C or less (waste not requiring a repository) is a desirable goal, none of the concepts proposed is likely to achieve it. All would produce primary and secondary wastes in sufficient amounts to require geologic disposal. Extremely low process losses would be required, together with extremely selective separation processes, to result in wastes with TRU contamination less than the Class C requirement, 100 nCi/gm (100 nanocuries per gram = 10-7 Ci/gm). The reduced thermal power could permit an increase in the initial loading density of the first repository and potentially in its capacity. This would have no direct effect on the need for first repository, although it would make a difference to at least the timing of and possibly the need for the second. Furthermore, thermal effects have not been shown to have detrimental impact on the long-term performance of a repository at Yucca Mountain. In fact, many have proposed that the elevated temperatures of the waste packages could provide for a ''dry" period in which no water could interact with the waste packages, thereby reducing the potential dissolution and transport in the first thousand years or so. This topic is further discussed in Appendix G (Ramspott et al., 1992). The S&T-released improvements in long-term performance would provide an advantage only if licensing and site characterization could be less extensive or lower in cost. No evidence is available to indicate that projections of long-term performance, which currently indicate relatively small individual and population doses, can simplify the licensing process or reduce the complexity of site characterization. The costs of construction and operation would not be significantly affected by incorporation of a high-integrity, lower-radioactivity-content waste form. The elimination of 14C for a Yucca Mountain repository would provide a marked advantage for showing compliance with the original EPA standard, but the action required is unusually extensive and expensive, if done solely for this purpose. It is speculative to assume that release limits in the present standard will prevail in the study currently being undertaken by the National Academy of Sciences. The net effect of the full implementation of any of the S&T systems proposed would not be to eliminate the need for a repository, but rather to offer the potential to improve its performance. Because of the time frame, to have any impact on the first repository would require a major and immediate commitment to an S&T system. If repository operations in the United States are to begin between 2010 and 2015, licensing application activities must be largely complete by 2001. At that time, the supporting technology necessary to obtain a license for the waste form in the repository environment must be available. In addition, full-scale reprocessing of LWR spent fuel must be licensed and available to support any of the transmutation systems. These operations must commence by about 2007 to furnish TRU to start ALMR by 2010. This is an extremely ambitious schedule unlikely to be achieved for any of the systems proposed, with the possible exception of LWRs. Impact on a Second Repository Implementation of an S&T system would have an impact on the second repository. Reduced heat load could allow for greater capacity in the first repository, provided legislative limits are removed. Its capacity could conceivably be expanded to more than twice the discharge of current LWRs or 200,000 MTU. This would be equivalent to an additional 40 or 50 years' discharge at current generation rates, thus postponing the need for another repository until about 2080. Similar benefits could also be provided by measures other than an S&T system, however. In the case of continuous electrical generation by systems with fairly low transmutation rates (ALMRs), TRUs could be continuously recycled to provide almost constant control of their inventory and material condition within the fuel cycle. Until that time when ALMRs are discontinued, requiring disposal of their inventory of TRUs in a geologic repository, only the fission products and secondary wastes in the resulting waste stream will need to be disposed. Of course, all the benefits of S&T for the first repository would also accrue to the second repository. Conclusions After considering the information above, the committee has reached the following conclusions about the impact of S&T on the repository. There is no evidence that application of advanced S&T holds sufficient merit for the United States to delay
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Nuclear Wastes: Technologies for Separations and Transmutation the development of the first nuclear waste repository to contain commercial spent fuel. Even with an S&T system, a geologic repository would still be needed. Application of S&T does not hold sufficient merit to abandon the once-through fuel cycle. While the need for a second repository could be delayed by S&T, there are several other ways, both legislative and technical, to increase the capacity of the first repository by a comparable amount. TRANSPORTATION-RELATED ISSUES Transportation of nuclear materials such as spent fuel and other wastes is the aspect of the nuclear fuel cycle that is the most visible to the public and touches them most closely. This section evaluates the impacts by S&T on nuclear material transportation. Nuclear Material Transport The potential impacts of nuclear material transportation increase with the toxicity and amount of nuclear material being transported and with the distance over which it is transported. These parameters, and thus the impacts, cannot be estimated for the various S&T options at present because many of the following factors have not yet been determined: the radionuclide composition of transmutation device fuels and wastes; the composition and volume of waste streams, both high-level and low-level, and the locations of the facilities that might be involved. The current state of affairs and the various S&T options can be classified into three categories: once-through, onsite reprocessing, and offsite reprocessing. The generic transportation steps required by each of these categories are depicted in Figure 6-1. The committee used this framework, other information presented, and their expert judgment based on previous experience in nuclear fuel cycles to develop qualitative characterizations of the activity and volume for each of the various transportation steps. The results are shown in Table 6-1. It is clear from the above analysis that going from a once-through scenario to one involving onsite reprocessing of transmutation-device fuel would result in a significant increase in the amount of radioactive material being transported on highways and railroads because of the need to ship secondary wastes and the spent fuel, recycle fuel, and HLW from reprocessing. However, going from onsite reprocessing of transmutation-device fuel to offsite reprocessing would result in a comparatively small increase. The characterization of the transportation impacts is of necessity severely limited. Because transportation of different materials can have very different risks per mile that overshadow differences in distances, the impact can be quite independent of the location of a facility. To achieve a representative figure, the transportation risk has been calculated for a case wherein LWRs are assumed to be located in Ohio (near the geographic centroid of LWRs in the United States), LWR reprocessing and ALMR plants are assumed to be located at Barnwell, South Carolina, and the repository at the Yucca Mountain study site in Nevada. Highway transportation was assumed. Incident-free and accident-related transportation risks to the public were calculated, as well as occupational exposures. The calculations, which used the ORIGEN-2 (Croff, 1980), HIGHWAY (Joy and Johnson, 1983), and RADTRAN 4 (Neuhauser and Kanipe, 1992) models, showed that the transportation risk was dominated by the transportation of spent fuel from the LWRs to reprocessing or the repository. The cancer fatality risk to the public was found to be 6.1 × 10-2 GWe/yr from the once-through cycle and 2.7 × 10-2 GWe/yr for actinide-burning in an ALMR with uranium recycling. These values, and even their relative magnitude, can be expected to change with the location of the various fuel-cycle facilities. Transportation Package Technology All three categories—once-through, onsite reprocessing, and offsite reprocessing—require one or more transportation packages (i.e., shipping casks and inserts) to move the radioactive material from one location to another. In most instances, the material being shipped is expected to have characteristics that do not differ substantially from materials now being transported. Spent fuels and HLW all emit substantial amounts of heat and penetrating gamma radiation that must be handled by the package. LLW and waste containing TRUs will be more voluminous, but their levels of radiation and heat emission will be much lower. The uranium product will also be voluminous, but will have low levels of radiation and essentially no heat emission. Packages currently exist for handling radioactive materials similar to all of those that would be generated in all the S&T scenarios. While package designs will depend on material-specific characteristics (e.g., physical dimensions, heat loads, and gamma-ray sources), there appear to be no technological impediments to their creation and certification. There is one possible exception to the above. If a transmutation device with a thermal neutron spectrum (e.g., LWR, ATW, PBR) were to be used, substantial amounts of 242,244Cm and 252Cf would build up (see Chapter 4 for more extensive discussion). After repeated recycling, the amounts of these materials could increase to levels such that the neutron emissions would dominate the gamma rays, affecting the radiation shielding considerations (Croff et al., 1977; Alexander and Croff, 1980). If this becomes the case
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Nuclear Wastes: Technologies for Separations and Transmutation FIGURE 6-1 Transportation flows for once-through and recycle cases. NOTE: Bold lines indicate highest-risk transportation operations. a Could be colocated with recycle fuel reprocessing and refabrication. and offsite transportation is required, additional technology development will be required to design and build packages for highly neutron-active, heat-emitting spent fuels. These packages may be very large and expensive despite payloads that are small relative to those of conventional casks. The same packages will probably be required for the fresh transmutation-device fuel as well, because the neutron emitters are recycled with the fuel. Regulations Related to Transportation Packages The U.S. Nuclear Regulatory Commission certifies (i.e., licenses) transportation packages under regulations it promulgates in Title 10, Part 71 of the Code of Federal Regulations (10CFR71). These regulations are based on design objectives (e.g., dose rates at certain distances, meeting various tests to assure structural integrity) and do not vary with the specifics of the material being considered. As a consequence, the regulatory structure required for the design and certification of radioactive material transportation packages for S&T scenarios is already in place, and it does not appear that significant modifications would be necessary. Conclusions The technology and regulations required to transport materials in an S&T fuel cycle are available unless extended recycle of actinides in thermal reactors were to occur.
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Nuclear Wastes: Technologies for Separations and Transmutation TABLE 6-1 Characterization of Transportation for Once-Through and Reprocessing Cases Waste Characteristic Category Transportation Step Activity Level Relative Volume Once-Through LWR Onsite Reprocess Offsite Reprocess LWR fuel from storage to reprocessing H M X X TRUs from LWR to transmutation devicea Mb-Lc L X X LWR HLW/TRU waste or spent fuel to repository H M X X X LWR reprocessing LLW to disposal Md-Ld H X X LWR uranium to storage, reenrichment, or disposal Mb-Lc M X X Transmutation-device spent fuel to reprocessing H M X Transmutation-device recycled fuel from reprocessing to transmutation device Md-Ld M X Transmutation-device HLW/TRU waste from reprocessing to repository H M X X Transmutation-device LLW from reprocessing to disposal M-L H X X a Step not present when LWR fuel reprocessing collocated with transmutation-device spent fuel reprocessing. b From pyrochemical processing. c From aqueous processing. d Collage of various waste streams of different activities. PROLIFERATION ISSUES There are three types of requirements—technical (knowledge and know-how), practical (facilities and personnel), and political—that a nation must meet to obtain materials in the quantities needed to make weapons (see Appendix H).4 These requirements, like economic costs, pose barriers to nuclear proliferation. The following section, Nuclear Nonproliferation and the Once-Through Fuel Cycle, briefly reviews the way these barriers shaped nonproliferation policies and established the LWR once-through fuel cycle as the baseline. The section, Proliferation Issues Related to Separations and Transmutation Systems, uses that baseline to assess the proliferation issues raised by the proposed S&T fuel cycles. The committee's conclusions are summarized in Summary and Conclusions. Appendix H provides additional information and references on proliferation policies and safeguards and also assesses the proliferation aspects of four specific S&T concepts. Nuclear Nonproliferation and the Once-Through Fuel Cycle Each of the declared nuclear weapon nations—the United States, the United Kingdom, and the former Soviet Union, followed later by France and China—created large dedicated programs for the production of the fissionable weapon materials, as well as civil programs to develop nuclear technology for electric power production and medicine. As many nations began nuclear research and development programs, concerns about the "dual use" of nuclear technology led to the creation of an International Atomic Energy Agency (IAEA) in 1957 with dual responsibilities: to foster the peaceful uses of nuclear energy through technical assistance and to restrain the spread of nuclear weapons and the ability to make them. The commercial LWR power system emerging in the 1960s answered the need for a nuclear fuel cycle that could enable many nations to use nuclear energy peacefully for medicine and power production while maintaining high barriers to nuclear proliferation (see Appendix H). Fresh LWR 4 The goals and criteria for materials accountancy are geared to the detection of quantities of safeguards significance of special nuclear materials for building a single nuclear explosive device, which the International Atomic Energy Agency takes to be 8 kg for plutonium, and, for uranium of > 20% enrichment an amount containing 25 kg of 235U. Publicly available literature suggests that sophisticated designs to increase enutron efficiency and retard explosive disassembly could require significantly less fissionable material, e.g., perhaps 4.5 to 5 kg of plutonium and 15 kg of uranium enriched to approximately 95% (see Appendix H).
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Nuclear Wastes: Technologies for Separations and Transmutation fuel contains low-enriched uranium (LEU) not usable for nuclear weapons. The technical and practical requirements for uranium enrichment put it beyond the reach of most nations for several decades. However, the spent LWR fuel poses a dilemma—the plutonium it contains is both bomb material and an energy resource. The intense radioactivity is a formidable hazard but would not prevent the reprocessing of the spent fuel and chemical separation of the plutonium. To minimize the proliferation risk, the spent LWR fuel could remain in storage pools for many decades, and the issues of reprocessing or permanent disposal deferred, provided means could be found to ensure that the spent fuel would not be diverted and used for producing plutonium for nuclear weapons. That concern was addressed by a combined political-technical barrier, called international safeguards, instituted by the IAEA as an essential part of its responsibilities.5 Thus, the LWR became the world standard for nuclear power and, as time passed, the once-through fuel cycle became the nonproliferation standard for the United States and many other nations. The Nuclear Nonproliferation Treaty (NPT) in 1970 greatly enhanced the international basis for nonproliferation. Some 150 member nations are parties to the treaty, entailing obligations for both nuclear weapon and nonnuclear-weapon nations. Moreover, the basis of IAEA safeguards for NPT nations was considerably strengthened to achieve more uniform agreements with full-scope coverage (see Appendix H). However, several nations with sizable nuclear programs remain outside the NPT framework, although all of them have agreed to pre-NPT-type safeguards with the IAEA that cover some facilities, such as the price of technical assistance and the ability to import nuclear technology from the major suppliers. The 1974 test of a nuclear explosive device by India, plus a series of public exposés in the 1980s involving Israel, Pakistan, and South Africa, revealed that those four non-NPT states had attained de facto but undeclared nuclear weapon capability using nuclear facilities not under safeguards (Spector and Smith, 1990). India and Israel used reactors and reprocessing to obtain plutonium. Pakistan and South Africa used enrichment to obtain High Enriched Uranium (HEU). Each public exposé was ambiguous enough to leave a figleaf of respectability for that nation's civil nuclear programs. Nonetheless, publicly available information summarized in Appendix H documents the fact that the weapon programs of the four nations, especially that of India, drew heavily on their civil nuclear programs.6 Still, this series of exposés did not seriously impugn the credibility of the IAEA safeguards system in effect, with a growing number of NPT signatories. Indeed, the gradual improvement in safeguards technologies, developed in cooperative programs between the IAEA and the nuclear powers and gradually deployed in NPT nonnuclear-weapon states, encouraged the perception that safeguards in NPT nations were adequate. From 1974 to 1980, U.S. nonproliferation policy aimed broadly at discouraging the civil use of plutonium and limiting the capability for enrichment and reprocessing to the European nuclear suppliers, the then Soviet Union, and Japan. During the 1980s, U.S. nonproliferation policy shifted to an emphasis on dealing with "rogue" nations, as several developing nations attained capability for enrichment or reprocessing on a production scale. The Achilles' heel of safeguards—undeclared facilities and activities—made headlines in 1991 as a result of IAEA special inspections in Iraq after the Persian Gulf War. An NPT signatory since the 1970s, Iraq was discovered to be pursuing a covert nuclear weapon program in violation of its treaty obligations. Benefiting from intelligence information and acting under U.N. Security Council mandate, the IAEA inspection team discovered an extensive uranium enrichment program that had gone undetected in previous regular inspections (see Appendix H). Their discoveries showed that Iraq was perhaps 3 to 5 years from having a source of HEU sufficient to manufacture about one nuclear weapon a year (Fainberg, 1993). The discoveries also underscored the importance of IAEA's performing special inspections, as the situation arises, to ensure the credibility of its safeguards. Whether this precedent can be applied to other nations remains to be seen. Recently, suspicious activities in North Korea, involving an undeclared reprocessing facility reported near Yongbyon, have raised apprehension in South Korea, Japan, and the United States. North Korea joined the NPT in the mid-1980s but balked at implementing a full-scope safeguards agreement with the IAEA. There is grave concern about the possibility that North Korea may have reprocessed fuel from a reactor that was shut down for about 100 days in 1989. At present, the political stand-off with North Korea and the fate of the IAEA safeguards there remain unresolved.7 5 Safeguard concepts are summarized in Appendix H. For a review of IAEA history and an extensive discussion of IAEA safeguards concepts, procedures, and problems, see Scheinman (1987) and Fischer and Szasz (1985). 6 Two other developing states that are not NPT members, Argentina and Brazil, also developed the technology and facilities capable of "dual-purpose" uranium enrichment—Argentina using gaseous diffusion and Brazil using the centrifuge approach. In the late 1980s, the two nations ended their nuclear rivalry and entered into a stringent bilateral nuclear-safeguards regime backed up by full-scope IAEA safeguards (see Appendix H). 7 On October 21, 1994, the long and difficult negotiations between the United States and North Korea bore fruit. The two nations signed an agreement under which North Korea would immediately freeze its nuclear weapons program and, over time, take steps to normalize its nuclear activities and facilities.
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Nuclear Wastes: Technologies for Separations and Transmutation The spread of de facto but undeclared nuclear weapon capability underscores the gradual crumbling of the technical barrier to proliferation—over a 40-year period, the knowledge, know-how, and even the special equipment necessary to produce fissionable weapon materials have become available (see Appendix H). A major enrichment or reprocessing facility, however, remains a formidable undertaking. Some 5 to 10 years is required in most countries to construct and put it in operation. Thus, practical barriers to proliferation may still be effective if concerned nations show that they are willing to take timely action—political, economic, and, as a last resort, military—given information from satellites, overflights, inspections where allowed, and intelligence sources. The U.S. "counter-proliferation" policy initiatives taken in 1993 give priority to bolstering the ability of the armed forces to respond to the proliferation of weapons of mass destruction in the post-Cold War world—particularly in the former Soviet bloc and in the hostile developing countries. It goes beyond political and economic efforts—meant to deter the acquisition of nuclear weapons or other weapons of mass destruction—to the potential use of military assets against a rogue nation or terrorist group with such weapons in their possession. Strengthened IAEA safeguards under a renewed NPT, perhaps buttressed by regional and bilateral agreements and safeguard regimes, could remain an essential mechanism to forestall the further spread of nuclear-weapon capability (Blix, 1992; Jennekens et al., 1992; Scheinman, 1992). This could be part of a larger initiative on cooperative security in the post-Cold War world, as recently proposed by two officials of the U.S. Department of Defense (Carter et al., 1992). Counter-proliferation means would remain a resort where cooperative means are not successful. In September 1993, the Clinton administration stated its policy on nonproliferation and the use of plutonium: "… The United States does not encourage the civil use of plutonium and, accordingly, does not itself engage in plutonium reprocessing for either nuclear power or nuclear explosive purposes. The United States, however, will maintain its existing commitments regarding the use of plutonium in civil nuclear programs in Western Europe and Japan" (Office of the President, 1993). The policy states the U.S. intention to give nonproliferation greater priority in diplomacy and in consideration of regional security and economic matters, to seek to promote nonproliferation efforts, and to make nonproliferation an integral part of its relations with countries around the world. The policy reinforces the use of the LWR once-through fuel cycle and discourages any S&T undertaking that uses spent LWR fuel in the United States for the foreseeable future.8 Proliferation Issues Related to S&T Systems The existence of major nuclear facilities and stores of fissionable materials that a nation has declared to be dedicated to civil purposes may indeed be perceived as benign by that nation's neighbors and other nations or, depending on the political situation, as a serious proliferation threat. The many possible proliferation scenarios can be classified into two main groups—diversion of materials from civil facilities or in transit, and abrogation of treaties or agreements by seizure of stores and facilities. Large stores of HEU for research, space power, or naval reactors, which could be further enriched to >90% 235U, as well as stores of separated plutonium would be prime concerns. Large enrichment plants, spent-fuel reprocessing plants, and fresh-fuel fabrication plants are the subjects of particular anxiety because their operations entail the use of fissionable materials in bulk form, which is more difficult to safeguard than spent fuel. All the S&T proposals call for such facilities (see Chapter 4). Additional facilities of concern include large reactors, spent-fuel storage depots, and waste repositories, all of which are part of the LWR once-through baseline. The assessment below compares S&T systems to that baseline. Appendix H provides more detail on the proliferation implications of particular S&T technologies and evaluates four illustrative S&T systems. Diversion Threats One type of diversion scenario involves covert operations that result in the gradual removal of material in amounts that are small relative to the normal capacity of a material store or production plant. Another is an overt operation by a subnational or terrorist group to seize fissionable materials in transit, or even to attack a fuel-cycle facility in order to steal the materials. It may not be easy to distinguish either type of operation from one conducted by agents of the government itself, masquerading as a terrorist group. For most diversion scenarios, technological issues may be as important as political issues in assessing the risk. National Diversion. The perceived risk of a national diversion of fissionable materials can be a serious matter—indeed, in 1981, Israel made an air strike against a reactor in Iraq just before it was due to start up. National diversion scenarios are potentially countered by stringent safeguards that apply materials accountability plus containment and surveillance techniques. At a typical reactor, the fuel rods provide a point of focus for safeguards (see Appendix H). The IAEA has devised special technologies plus a variety 8 S&T requires spent nuclear power reactor fuel reprocessing which has weapons proliferation implications and hence is of international concern. There would not be more plutonium around; in fact there would be less. But the plutonium in the spent fuel would be opened up and thus gets into a more accessible form.
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Nuclear Wastes: Technologies for Separations and Transmutation of techniques to support inspections and checking of records at both regular intervals and randomly chosen times. Accountability for bulk quantities of enriched uranium or plutonium, on the other hand, has its limitations under the best of circumstances. At present-day fuel reprocessing or fabrication plants, conventional materials accountability practices strive to achieve a materials balance on the order of 1% of the total fissile material in the facility. For example, a large reprocessing plant such as those in operation in Europe has an maximum throughput of about 100 MgHM of spent fuel per month. As is explained in Appendix H, this would yield perhaps 3 kg/d of weapons-grade plutonium; a 1% uncertainty could be equivalent to two plutonium weapons per year. This figure is high enough to raise concerns in many situations. Some proponents claim that a materials balance on the order of 0.3 to 0.1% could be achieved with advanced practices, however. Typical present-day commercial facilities for aqueous reprocessing of spent fuel use semiremote maintenance with many maintenance portals and drains, which pose a challenge to secure containment and surveillance safeguards. However, the diversion potential might be reduced by designing plants for optimum containment and surveillance safeguards rather than for ready maintenance, e.g., with highly restricted access, entirely remote operation using robotics, and automated materials accountability. The potential for diversion might also be reduced by integrating the reactor and fuel processing facility, as described in the ALMR/IFR proposal (see Appendix H). Reducing the uncertainty level by an order of magnitude (to the 0.1% level) in facilities designed, constructed, and operated so as to facilitate the application of safeguards might be enough to remove national diversion as a serious threat associated with reprocessing and fuel fabrication. However, such a reduction would require much more cooperation with the IAEA on the part of facility designers, constructors, and operators than has typically been the case in the past. Diversion by Terrorists or Subnational Groups. Seizure by terrorists or subnational groups can take many forms. Even if such groups have only limited means at their disposal, they pose a threat in a modern, open society. Even though the nuclear material available by theft or seizure might be far from optimal for a nuclear explosive, and a group would require shielded equipment to handle and process any intensely radioactive material, the threat still exists that plutonium, if available in sufficient quantities, could be used to make a crude device capable of at least a few kilotons of nuclear yield. While the yield would not be predictable for material containing much 240 Pu, the threat of spreading plutonium over a city by any explosive means would surely terrify the public. Of course, nations can take many measures to provide high security for key nuclear facilities and shipments, but such measures themselves could be unsettling to the public. As a rule of thumb, the fewer the shipments required, the less directly usable or convertible the material, and the less attractive the facilities as a possible terrorist target, the better. For S&T systems, the terrorist scenarios present few features not raised in discussions during the evaluation by the International Nuclear Fuel Cycle Evaluation Group (1980). At that time, governments expressed confidence that terrorist attacks could be deterred or be resisted as necessary. Perhaps the biggest change is the more sober attitude of governments today about the possibilities open to determined terrorists and the difficulty of controlling them in an open democracy. One cannot do more than qualitatively assess the S&T proposals for this proliferation threat. Major fuel-processing facilities with large quantities of plutonium-bearing material in bulk form, which might be potential targets, may require isolated siting and high security like that of a military base. Also, the requirements for frequent fuel shipments would raise questions about transportation-related risks for most of the S&T proposals. A safeguards study of an integrated ALMR/IFR with pyroprocessing suggests that such a facility is an unattractive target for a takeover and theft of material (Wymer et al., 1992). The material contained in the facility is less directly useful, and the sealed, self-contained site may make it easier to protect. Perhaps a similar integration of small, more readily guarded processing facilities at the reactor could be accomplished for S&T proposals that use aqueous technology. However, the kind of steps that make a facility minimally useful for converting material if the facility is seized, and enhance containment and surveillance techniques, tend to get in the way of reliable operation. In addition, it might be easier to protect a few large facilities than myriad small ones. For aqueous reprocessing, therefore, it is not clear that one would gain by going to multiple, small facilities. Abrogation Threats Abrogation raises mainly political issues. Technology may play a part in lengthening the time or reducing the extent to which the seized facilities may be used for weapon materials production. In the nightmare abrogation scenario, the nation trains its personnel at the facility in question, but secretly prepares elsewhere the rest of what it needs for a nuclear weapon, then seizes the facility, throws out the inspectors on some pretext, and prepares the bomb material it needs within a few days or weeks. Presumably, the more separated nuclear material a facility contains (i.e., more bombs could be produced) and the more readily the facility itself can be adapted to weapon materials production (i.e.,
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Nuclear Wastes: Technologies for Separations and Transmutation the production time scale would be shorter), the more the perceived threat of abrogation would presumably increase. Whether a nation would actually abrogate treaties and then misuse its civil nuclear resources has never been put to the test. The few nonnuclear-weapon nations credited with nuclear-weapon capability attained this capability using facilities that were outside a safeguards regime; other proliferation barriers did not deter them. However, an abrogation threat is very much a matter of perceptions.9 Without full-scope safeguards, a nation might take over the facilities and obtain nuclear weapon materials without other nations being aware in time for effective counteraction. Even with full-scope safeguards, the presence of large reprocessing facilities and/or enrichment facilities in the S&T proposals tend to make them targets in national abrogation scenarios. A new feature of the ALMR/IFR proposal is a reactor with integral onsite processing, where the nuclear material at the plant and the accessible plant equipment may not be well suited for rapidly obtaining weapon material. The IFR safeguards study indicates that a plant could be designed to reduce the risk under abrogation scenarios (see Appendix H). Unfortunately, the ALMR/IFR proposal has not yet been developed in enough detail to permit a definitive evaluation. Conclusions Nuclear proliferation is an issue even for the once-through fuel cycle, where it is addressed by domestic security measures and especially by international safeguards to deter the misuse of reactors, enrichment facilities, and stored spent fuel. Proliferation risks would generally be greater with widespread implementation of S&T systems in the many nations using nuclear power, mainly because of two factors: (1) the availability of bulk quantities of plutonium in separated or readily converted form at various places in the fuel cycle, which can be a challenge for safeguards even with stringent materials accountability and surveillance systems; and (2) the availability of large reprocessing facilities that could be misused for production of fissionable weapon materials, e.g., after treaty withdrawal or abrogation. The Clinton administration's policy announced in September 1993 reaffirms the link between U.S. nonproliferation goals and concerns vis-à-vis civil plutonium reprocessing and its use in nuclear power, as emphasized by the United States in the late 1970s, and discourages any S&T undertaking with LWR spent fuel in the United States for the foreseeable future. HEALTH AND SAFETY ISSUES Health Impacts The health effects on the population as a result of exposure to radiation can be calculated. The analyst first defines the principal pathways by which radiation exposure could occur and then calculates just how much of the radioactivity can move through each pathway. Finally, it must be determined just how large a dose of radiation the exposed person would receive and what health effects it would produce. In most cases, the data required to perform such a calculation are not completely known, so there is considerable uncertainty in the final result of the calculation. The collective population dose is the sum of the individual doses to a particular population. Doses of this type are expressed in units of person-sievert (1 pr-Sv = 100 pr-rem). Risk coefficients for various health effects have been developed over the last 50 years. For example, the BEIR V report (National Research Council, 1990) suggests that a collective dose-risk coefficient of 0.08 latent cancer fatalities/pr-Sv (8 × 10-4 cancers/pr-rem) can be postulated for a demographically average group following an acute dose. The report notes that accumulation of the same dose over weeks or months is expected to reduce the lifetime risk by a factor of 2 or more. This would give about 4 × 10-4 cancers/person-rem for the collective dose-risk coefficient for the case considered here. Health Effects of Fuel Cycles Various studies in recent years have quantified the health effects of various nuclear fuel cycles. Tables 6-2, 6-3, and 6-4 show the results of two of these studies, one done by the National Council on Radiation Protection and Measurements (NCRP) and the other by Oak Ridge National Laboratory (ORNL). The results of the NCRP study are expressed in terms of pr-Sv, however, and those of the ORNL study as the number of fatal health effects. By far the most likely fatal effects are latent cancer fatalities. (The columns labeled "general public mortalities [radiological]" are, for all practical purposes, latent cancer fatalities.) Table 6-5 puts these three study results on a common basis by converting pr-Sv to health effects. It also equalizes the different dose commitments; the NCRP calculation assumed a 100-year dose commitment where ORNL used 1,000 years. It is interesting to note that the societal impact of any one of these fuel cycles is less than one latent cancer fatality per reactor-year. Note also that the generation of 20% of nuclear electricity by ALMRs would reduce mining and milling risks, since less uranium would need to be mined. On the other hand, since ALMRs recycle the actinides, they must use reprocessing, which introduces a risk not present 9 Several observers have speculated that the prospect of a future Iraqi abrogation of the NPT, with immediate seizure and reprocessing of accumulated spent fuel from the Osirak reactor, was a significant factor in motivating the 1981 Israeli air attack on the reactor before it went critical.
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Nuclear Wastes: Technologies for Separations and Transmutation TABLE 6-2 Summary of Collective Effective Dose Equivalents to the Regional Populations Normalized to a 1-GWe Reactor Operating 80% of the Time Facility Collective Effective Dose Equivalent (person-rem/yr) Basis of Estimate Mining 94 Weighted for two types of model mines (one-half open pit and three underground) Milling 25 0.4 model mill Conversion 0.03 Weighted for two plants, for 29.8 GWe Enrichment 0.01 Paducah plus Oak Ridge for 29.8 GWe Fabrication 0.004 Weighted for seven plants for 29.8 GWe Reactor 4.8 1980 data for 47 plants Low-level waste storage — No estimate available Transportation (incident-free) 7.1 Excludes decommissioning wastes (accidents) 5.4 Total 136 NOTE: 1 person-rem/yr = 0.01 person-Sv/yr. SOURCE: National Council on Radiation Protection and Measurements (1987). in the once-through cycle. The magnitude of these latent cancer risks is interesting, but the reader should be aware that the calculated risks vary depending on assumptions and have quite large uncertainties—perhaps a factor of 2 or more. The values from the two groups (shown in Table 6-5) are consistent with that level of uncertainty. Even with this level of uncertainty, it is evident that the difference in risk for the two fuel cycles is small. TABLE 6-3 Summary of Potential Health Risks Among the Total U.S. Population per GWe-year for the Once-Through LWR Fuel Cycle, Assuming 1,000-Year Dose Commitments Occupational Mortality. Injury and Disease Source of Risk Radiological Nonradiological General Public Mortalities (radiological) Total Mortality Occupational General Public Total Injury and Disease Uranium mining 0.081 0.025 0.105 0.211 3.47 0.083 3.55 Uranium milling 0.012 <0.001 0.217 0.239 2.64 0.168 3.81 UF6 conversion 0.001 <0.001 0.076 0.077 a <0.001 0.001 Enrichment 0.002 <0.001 <0.001 -0.002 a 0.002 0.002 Fuel fabrication 0.054 <0.001 <0.001 0.054 a 0.06 — Power generation 0.12 0.01 0.028 0.158 5.0 0.10 5.1 Transportation 0.001 0.01 0.061 0.072 0.17 a 0.17 Reprocessing — a — — — — — Waste management a a 0.008 0.008 a 0.016 0.016 Catastrophic accident a a 0.1 0.1 a a 0.15 Total 0.271 0.045 0.595 0.921 11.28 0.429 11.8 a These values are not currently available, but they are expected to be small relative to those presented. SOURCE: Michaels (1992; and private communication, 1993). Health Effects of Transmutation The three claimed beneficial effects of transmutation on radiological health risks are: (1) it lowers the incidence of harmful effects on health-related mining and milling activities by reducing the amount of natural uranium required to produce a given amount of electricity, (2) it lowers the long-term incidence of harmful effects on health of HLW disposal, and (3) it reduces the radiation exposure in some
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Nuclear Wastes: Technologies for Separations and Transmutation POLICY, INSTITUTIONAL, AND MANAGEMENT ISSUES When it was first instituted, the Atomic Energy Commission (AEC) had both developmental and licensing authority over civilian nuclear facilities. Recognition of the embodied conflict of interest and increasing public concern over nuclear issues caused the splitting of the AEC into an energy research and development agency and a separate regulatory agency (the U.S. Nuclear Regulatory Commission), which led to greater public involvement in the licensing process. One result was an extended period during which requirements placed on nuclear facilities were changing even as the facilities were being built. These changes greatly increased costs and prolonged construction schedules for many nuclear facilities, and in some cases, provoked outright cancellation. Requirements were changed at the regulatory level (e.g., retrofits to reactor safety systems and the West Valley Fuel Reprocessing Plant) as well as at the policy level (e.g., President Carter's decision to oppose reprocessing). Licensing and construction of major new nuclear facilities is at a standstill in the United States. This results in part from an adequate immediate supply of electrical generating capacity and a current surplus of uranium (resulting in a lack of need for reprocessing and recycling facilities). However, a factor at least as important is the reluctance of investors (utility or industrial) to risk large sums of money to build nuclear facilities because their investments might be jeopardized through regulatory or policy changes. This concern appears to be so widespread that it is unlikely any investor will attempt to build a major nuclear facility without guarantees from the federal government amounting to the project being government financed. This outlook can be expected to persist until a sufficient number of nuclear facilities have been built over a sustained period of regulatory stability to restore investor confidence. Policy Long-term major national commitments with strong, stable, centralized government leadership and financing and operating within a favorable public perception of nuclear enterprises will be required if S&T is to become a significant factor in nuclear waste management. On the basis of the history of the past decade of nuclear activities, it is difficult to visualize any such circumstances in the immediate future. Given this reality, it is necessary to consider (1) under what conditions future policymakers would find it prudent to undertake to implement S&T and (2) whether those conditions are likely enough to occur that research should continue, and if so, at what level. The following are some of the conditions that might lead policymakers to advocate S&T and to support the legal, financial, and managerial provisions needed to bring it to fruition: if regulators or the public considered the technical estimates of repository risks to be too uncertain or too high, and if the estimated risks or uncertainties could be reduced to acceptable levels by improving the waste form or by changing or reducing the radioactive constituents of the waste; if difficulty in building the first repository made building a second repository undesirable or infeasible, and the limitation on amount of spent fuel that could be placed in the first repository could not be altered; if the federal government were unable to build and license a repository for institutional or technical reasons; if economic, fuel-supply, and societal conditions changed, so that it was decided to reprocess to recover fissile material, presenting the opportunity to transmute some constituents as a waste-management measure; if research uncovered an S&T system that did not present the problems inherent in those currently proposed; or if attitudes about nuclear power changed, perhaps as a result of concern about the worldwide environmental effects of other energy sources. None of these conditions exists at present. However, one or more might come into being during the long period of time this committee estimates will ensue before economic and energy-supply conditions make S&T a practical economic alternative to the once-through reactor fuel cycle. In anticipation of such an eventuality occurring, a carefully planned but focused research program on S&T should be carried on. Licensing, Siting, and Public Acceptance Creation of a S&T system would require legislative and administrative steps establishing the policy basis for a national commitment to large expenditures for the many facilities needed. The operations of the various facilities would link numerous organizations over a period of many decades. Siting restrictions imposed by certain state governments would have to be relaxed. Creating and reviewing an environmental impact statement for an S&T system may be a more contentious undertaking than was the process for drawing up the Generic Environmental Statement on Mixed Oxides, which was discontinued in the mid-1970s. Difficulties such as the lack of demonstrated need, economics, technical uncertainties, and particularly those associated with licensing and siting, are becoming increasingly important impediments to concrete actions in nuclear matters. Mechanisms are available through which opposition
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Nuclear Wastes: Technologies for Separations and Transmutation can influence policy and action more effectively than before: state laws and regulations in a domain that was historically federal; controls over nuclear matters at the state level through controls on nonnuclear hazardous materials criteria such as the Resource Conservation and Recovery Act (RCRA); and a continuing series of intervention lawsuits. Finally, the public's distrust of the ability of the federal government to conduct programs effectively undermines its capacity to organize, manage, and finance a program as large as would be required for S&T implementation. There are many recent examples of the effects of the difficulty in completing nuclear-related projects: A decade will be needed for the licensing and certification of Advanced Light-Water Reactors, even though they are a direct advance from 100 presently operating LWRs in the United States and have vastly improved safety characteristics. The government has invested over $1.6 billion through April 1995 in Waste Isolation Pilot Plant (WIPP), a deep underground salt bed repository in New Mexico that was started in January 1975 and is now over 20 years old. The repository facility was fully constructed and capable of receiving waste in October 1988. After extensive review, DOE declared it ready for safe operation and authorized it to receive several small amounts of waste for bin tests deposits in about 1991. However, this operation was never started. It is still not operational as of the time of this report. The continuing delays in the planned operation of Yucca Mountain are indicative of the difficulties licensing and siting a complete S&T system could encounter. No LLW disposal site proposed since the Low-Level Waste Policy Act of 1980, amended in 1985, is operational. All proposed sites under the state compact agreements have been challenged and delayed. Although DOE was expected to take custody of spent fuel from commercial reactors in 1998, it is widely assumed that this schedule will not be met. Utilities are working now to find a way to store fuel on site indefinitely. Thus, in the present context of institutional relationships in the United States, developing, siting, and licensing an entire system of high-technology nuclear facilities, for which few precedents exist, are likely to take a very long time, cost a great deal, and continue to lack the assurance of eventual success. Any decision to build and operate an S&T system must take these constraints into account. Since no systematic effort has been undertaken to gauge public opinion on transmutation, McCabe and Colglazier (1992) concluded, in a report for the committee's introductory workshop, that any characterization of public opinion on the subject is largely speculative. Newspaper and magazine articles on the subject of S&T have largely been based on press releases and interviews with proponents. These articles generally describe these proposals favorably, as potential technical solutions to the disposal of radioactive waste. The articles contain little or no discussion of the technical uncertainties, the potential management, financial, and institutional complexities, and the length of time needed for the research and operations that this committee has identified as barriers to implementation of current proposals. Thus, any current public support that may exist for S&T is likely to be based on very incomplete information. Before S&T proposals are implemented, the public will learn more about the great size, complexity, and number of nuclear-based facilities necessary to implement any of the current S&T proposals. Financial Provisions The facilities listed above—reprocessing, fuel fabrication, and transmutation—will be expensive to build and operate, as recent experience with even the simplest nuclear plant demonstrates. The first cost of any one of them is likely to be several billions of dollars. Moreover, the operation of an S&T cycle is certain to be more expensive than the once-through fuel cycle, until the price of uranium fuel makes the actinides from LWR fuel an economical substitute fuel source (which is many decades in the future). Thus, financing and supporting the entire system is not likely to be financially practical for any one utility, or any industrial group, without government subsidies or guarantees. In the end, any extra costs beyond those of the current fuel management system must be borne by electricity users or taxpayers. The fact that these incremental costs will have to be incurred in the next two to three decades to reduce the potential risk to society for hundreds to hundreds of thousands of years in the future, while short-term health risks may also be increased, will make the large-scale, long-term financing support needed for an S&T system difficult to obtain and ensure. An estimate can be made of the time scale and the cost required to deploy an S&T system based on LWRs or ALMRs, assuming that development can be completed and that favorable institutional arrangements can be achieved. The licensing, construction, and initial operation of a S&T system of sufficient scale to ever begin to affect spent fuel emplacement in a geologic repository would require one to two decades after a system feasibility demonstration, and an expenditure of $20 to $40 billion beyond the costs of development and demonstration. Additional time and a much larger investment of funds would be necessary to start up an S&T system of sufficient scale to reduce repository hazards significantly or to affect the need for a second repository.
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Nuclear Wastes: Technologies for Separations and Transmutation If electric utilities, chemical companies, and other industrial organizations are to participate as they have in the past deployment of nuclear power reactors and fuel-cycle facilities, many private organizations and their state and federal regulatory bodies must coordinate their plans, decisions, and expenditures to ensure the continuing integrity of the S&T system. Indeed, private utility funding presumably would be contingent on agreement by the many state public utility commissions that such long-term commitments are prudent investments. In view of the history of nuclear power and commercial reprocessing in the United States, federal guarantees are likely to be necessary for such industries to be involved with the construction and operation of the required S&T facilities. System Requirements The S&T system required to achieve the prospective benefits would comprise many interdependent components, e.g., waste-transmutation reactors, spent-fuel reprocessing plants, recycled fuel fabrication plants, plants to package the residual waste for ultimate disposal, and mechanisms to transport fuel and waste between the facilities. Developing, building, and operating selected individual components of the system would yield little benefit. A complete system incorporating many facilities, all successfully operating in a synchronized fashion for many decades to centuries, would be required in order to have a significant effect. If any one of the components of the system cannot be developed, licensed, and operated with reasonably high reliability, the desired benefits will be foreclosed. Implementation of S&T technology would require the construction and licensing of the following four new types of fuel-cycle facilities in addition to those currently used or planned for a once-through LWR fuel cycle: LWR fuel reprocessing: One or more large plants would be required to receive LWR spent fuel, reprocess it to recover the radionuclides to be transmuted, and treat wastes in preparation for transportation and disposal. These might be based on existing technology (e.g., aqueous fuel reprocessing), pyrochemical reprocessing, or other technologies to be determined. Transmutation devices: A number of devices would be needed to transmute the recovered radionuclides. These might be LWRs at the outset, succeeded or augmented by one or more advanced transmutation devices such as those discussed in Chapter 4. To a large extent, these would substitute for other electricity-generating plants. Actinide/fission-product fuel/target fabrication: S&T involves transmutation of the TRU and fission-product radionuclides recovered during reprocessing. Transmutation requires that these radionuclides be fabricated remotely into an acceptable fuel or target for insertion into the reactor. In some cases, such as the fluid-fueled ATW, the fuel would always remain in slurry or solution form. In most other cases, the radionuclides must be fabricated into metal-clad rods containing oxides or metal. Transmutation-device fuel/target reprocessing: After irradiation, the transmutation-device fuel or targets must be reprocessed to recover the untransmuted radionuclides for refabrication and continued irradiation and to send undesirable transmutation products to the waste stream. This facility might be similar to what is used for reprocessing LWR fuel or it might employ an entirely different technology. For most systems, the reprocessing facility is physically disconnected from the reactor (and usually geographically separated), but in the case of the ATW, the reprocessing plant is integrated into the reactor design. In any of the S&T systems the time required to make meaningful contributions to waste disposal is measured in decades.17 Therefore, unless the total system can be implemented and sustained reliably for several decades, the waste-reduction benefits are significantly diminished because the large quantities of actinides and fission products remaining would still need to be managed if continued operation broke down at any point in the cycle. Organizations, rules and regulations, assignments of responsibility, and funding arrangements would need to be established in ways that would provide reasonable assurance of the necessary stability over many decades. Summary The sustained commitment needed to develop and demonstrate the technologies and to build and operate the succession of required major facilities of an S&T system would represent institutional complexity and magnitude unprecedented in the civilian sector. Because of the required commitment of funding and the technical and financial risk entailed, it appears that it would be necessary for the U.S. government to accept the lead management and financial responsibility. A cohesive national intent would have to be established, a tightly managed development program organized, and the funds for effective implementation regularly provided. The last two decades of the U.S. government-led nuclear programs provide little confidence that such conditions can be established and maintained. REGULATORY ISSUES This section summarizes the status of the regulations applicable to the major steps in the once-through fuel cycle 17 The impact of waste forms and repository loading would be seen earlier.
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Nuclear Wastes: Technologies for Separations and Transmutation and the handling of the resulting waste, as well as the possible applicability of current regulations to the additional facilities and steps required by an S&T fuel cycle. Current Federal Regulations Once-Through Cycle The various aspects of the once-through cycle are subject to several of the titles of the U.S. Code of Federal Regulations. The applicable portions of the code are noted in the text below. Uranium Mining. No license from the Nuclear Regulatory Commission (NRC) is required for the mining of uranium. However, uranium mines are subject to a variety of other laws. The Federal Water Pollution Control Act (FWPCA) (USC 33, 1251-1387) directs the Environmental Protection Agency (EPA) to set effluent limitations and new source performance standards for uranium mines (40CFR440.34). Under the Clean Air Act (CAA), the EPA has issued a national emission standard for 222Rn emissions from underground uranium mines (40CFR61.20-61.26) and performance standards for metallic-mineral processing plants, which include open-pit uranium mining operations (40CFR60.380-60.386). The Safe Drinking Water Act (SDWA) (USC 42 300f-330j-26) would apply as well if a mine were contaminating public drinking-water supplies (USC 42 300i[a]; Scott, 1984). Uranium Milling. Either the NRC or the so-called "agreement states" license uranium mills.18 The regulations cover design, siting, environmental monitoring and planning, finances, inspections, operations, shutdowns, tailings, and decommissioning (10CFR40). NRC licensing of a mill may require the filing of an environmental impact statement (CFR 10 51.20[b]). The NRC's Standards for Protection Against Radiation (10CFR20)19 (commonly called the NRC radiation protection standards) apply to milling operations (10CFR20.2). These regulations protect employees and offsite individuals by setting limits on permissible radiation exposure levels (10CFR20.101/20.105) and on radioactivity in effluents (10CFR20.106). The regulations also direct NRC licensees to "make every reasonable effort to maintain radiation exposures, and releases of radioactive materials in effluent to unrestricted areas, 'As Low As Reasonably Achievable (ALARA)'" (10CFR20.1[c]). The ALARA concept is a principal foundation of NRC regulation (see Bremberg, 1989). EPA's environmental radiation protection standards for nuclear power operations (40CFR190)20 (EPA nuclear fuel-cycle standards) also govern uranium milling. In addition, EPA has adopted standards for radionuclide emissions under the CAA (the EPA radionuclide standards) that govern mills. However, the 1990 CAA amendments provide that EPA may rescind its authority over mills and other fuel-cycle facilities if it determines that regulation by the NRC "provides an ample margin of safety to protect the public health" (USC 42 7412[d]).21 EPA also regulates mills under the FWPCA. Each mill must obtain a permit under the National Pollutant Discharge Elimination System (NPDES) (40CFR125). However, in 1976 the Supreme Court held that pollutants subject to the FWPCA do not include "by-product," "source," or "special nuclear" material regulated by DOE and NRC under the Atomic Energy Act (AEA) of 1984 (Train v. Colorado Public Interest Research Group, 1976). Therefore, an NPDES permit limits only nonradioactive mill effluents. Conversion. Conversion facilities are subject to many of the same requirements as uranium mills. The NRC or agreement states license conversion plants pursuant to the regulations for source material (10CFR40) and special nuclear material (10CFR70). These regulations cover, for example, effluent monitoring, physical security and contingency plans, materials accounting and control, decommissioning, prevention of accidents, and/or protection if accidents occur. The NRC radiation protection standards (10CFR20) apply, as do the EPA nuclear fuel-cycle standards (40CFR190) and EPA radionuclide standards (40CFR61). Enrichment. Existing DOE enrichment facilities have historically been exempt from NRC licensing requirements (10CFR40.11, 50.11, 70.11). Instead, they had to comply with DOE orders and EPA requirements. However, with the establishment of the U.S. Enrichment Corporation, the future operation of these plants will be regulated by the NRC as well as the EPA and the Occupational Health and Safety Administration under rules promulgated in 10CFR76. Legacy issues will continue to be regulated under DOE orders and EPA requirements. Planned commercial enrichment facilities, such as the one proposed by the Louisiana Energy Services partnership, would originally have had to meet the NRC licensing requirements for production and utilization facilities, including 18 An agreement state as designated in an NRC regulation means any state with which the NRC has entered into an effective agreement under subsection 274b of the Atomic Energy Act of 1954 to carry out certain aspects of the regulation of radiation. 19 The standards were substantially revised in 1991. See 56 Federal Register 23360 (1991). 20 These were issued pursuant to EPA's Atomic Energy Act authority derived from Reorganization Plan No. 3 of 1970, U.S. Code Title 5, Appendix 1. 21 See also 56 Federal Register 18735 (1991).
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Nuclear Wastes: Technologies for Separations and Transmutation reactors (10CFR50). Under these requirements, the facility would have had to first obtain a construction permit and then a license to operate the facility (10CFR50.22-50.23). However, in 1990, Congress authorized the NRC to issue a combined construction permit and operating license for uranium enrichment and separation facilities (PL101-575). The NRC has developed design criteria and regulations for enrichment facilities (53 Federal Register, 1988; 56 Federal Register, 1991), and the 1990 legislation mandates that an environmental impact statement be submitted and an adjudicatory hearing be held. Commercial enrichment facilities must also comply with NRC radiation protection standards (10CFR20), EPA nuclear fuel-cycle standards (40CFR190), and EPA radionuclide standards (40CFR61). Fuel Fabrication. Commercial fuel fabrication facilities are subject to NRC licensing regulations for source material (10CFR40) and special nuclear material (10CFR70). They are also subject to NRC radiation protection standards (10CFR20), EPA nuclear fuel-cycle standards (40CFR190), and EPA radionuclide standards (40CFR61). Licensing of Nuclear Power Plant Operations. The AEA of 1984 established a two-step licensing process for commercial nuclear power plants, whereby a utility applies for a construction permit (at which time a public hearing is required) and then, after plant construction, seeks an operating license (subject to another public hearing upon request of an interested party) (USC 42 2235/2239(a)). In 1989, however, after several years of unsuccessful attempts to convince Congress to amend the AEA to provide for a one-step process, the NRC adopted regulations (10CFR52) providing for a "combined license" (10CFR52; 54 Federal Register, 1989). Under this procedure, the NRC may issue a construction permit with a conditional operating license (10CFR52.97). After completion of the plant, and upon an NRC finding of conformity with the "acceptance criteria" specified in the combined license, the NRC can authorize plant operation (10CFR52.103). This new licensing process revises the current approach in two ways. First, it requires that most of the issues previously raised in operating license hearings be scrutinized early in the licensing process at the time of the application for the construction permit. For example, the adequacy of emergency planning (10CFR50.47; 54 Federal Register , 1989) and whether the facility will be operated in conformity with the AEA must now be considered up front (10CFR52.97). Second, the new regulations diminish the opportunity to apply for a postconstruction hearing. For example, they would not provide the right to a hearing concerning new safety information that comes to light during construction and raises new questions about the plant's conformity with the AEA (10CFR52.103). The full Court of Appeals for the District of Columbia Circuit recently upheld the legality of the new NRC regulations after they had been vacated, in part, by a three-judge panel. Once licensed and operating, a nuclear power plant is subject to an array of regulations governing operations (10CFR50.54), inspections (10CFR50.70), recordkeeping (10CFR50.71), emergency notification (10CFR50.72), reporting (10CFR50.73), physical protection of facilities and nuclear materials (10CFR73), material accounting and control (10CFR75), and financial protection for accidents and decommissioning (10CFR140). (A power plant license includes related operational instructions, including "limiting conditions for operation" that require shutdown under specified circumstances.) Once a year the nuclear utility must report offsite dose calculations that demonstrate compliance with the EPA nuclear fuel-cycle standards, and twice a year a facility must report effluent quantities (10CFR190; 56 Federal Register, 1991). Separations/Reprocessing. The AEA defines a "production facility," in part, as "any equipment or device determined by rule of the Commission to be capable of the production of special nuclear material in such quantity as to be of significance to the common defense and security, or in such manner as to affect the health and safety of the public …" (AEA, Section 11[v]). On its face, this definition does not appear to encompass reprocessing facilities. However, in implementing regulations the NRC has defined production facility expansively to include not only a facility that produces special nuclear material anew but also one that separates existing special nuclear material from other substances, i.e., reprocessing. NRC regulations state that "any facility designed or used for the separation of isotopes of uranium or … plutonium, except for laboratory-scale facilities" constitutes a "production facility" requiring licensing of construction and operation (10CFR50.2). Such a facility would be licensed under 10CFR50, the standard licensing regulations for nuclear power facilities. A reprocessing facility may not be eligible for a combined license under the 10CFR52 regulations for nuclear power plants adopted by the NRC in 1989. However, a reprocessing facility might, nevertheless, still be eligible for a combined license if it fell within the exception created by Congress in 1990 for plants "capable of separating the isotopes of uranium or enriching uranium in the isotope 235" (AEA, 11[v]; USC 42 2014[v]) (see previous discussion under Enrichment). A separations and reprocessing plant would be subject to NRC radiation protection standards (10CFR20) as well as the EPA nuclear fuel-cycle standards (40CFR190) to the extent that reprocessing or separations "directly support[s] the production of electrical power for public use utilizing nuclear energy. …" (40CFR190.02[b]).
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Nuclear Wastes: Technologies for Separations and Transmutation Transmutation by Reactor. NRC regulations define a "utilization facility" subject to NRC licensing as "any nuclear reactor other than one designed or used primarily for the formation of plutonium or 233U" (10CFR50.2). The Energy Reorganization Act of 1974 provided that demonstration liquid-metal fast breeder reactors and any other new "demonstration nuclear reactors" were subject to NRC licensing "when operated as part of the power generation facilities of an electric utility system, or when operated in any other manner for the purpose of demonstrating the suitability for commercial application of such [reactors]." Transmutation by Accelerator. Preliminary research and discussions with NRC and congressional committee lawyers have not given the committee a clear answer as to whether, under existing law, a license would be required for the construction and operation of an accelerator used to transmute waste. The AEA requires a license for the construction and operation of any "production" or "utilization" facility with the exception of "facilities under contract with and for the account of" DOE (AEA, section 100). The AEA definition of a production facility appears above; NRC regulations define a production facility, in part, as follows: Any facility designed or used for the processing of irradiated materials containing special nuclear material, except (i) laboratory-scale facilities designed or used for experimental or analytical purposes, (ii) facilities in which the only special nuclear materials contained in the irradiated material to be processed are uranium enriched in the isotope U-235 and plutonium produced by the irradiation, if the material processed contains not more than 10-6 grams of plutonium per gram of U-235 and has fission product activity not in excess of 0.25 millicuries of fission products per gram of U-235; and (iii) facilities in which processing is conducted pursuant to a license issued under Parts 30 and 70 of this chapter, or equivalent regulations of an Agreement State, for the receipt, possession, use, and transfer of irradiated special nuclear material (10CFR50.2). In discussing the difference between the previous definitions discussed in the above statutory and regulatory definitions, the key to whether an accelerator transmuting waste would be considered a production facility for licensing purposes was likely to be (1) whether special nuclear material or some other fissionable isotope would be produced by the accelerator or (2) whether neutron bombardment could somehow cause additional special nuclear material to be separated from the material being processed. If neither of these questions could be answered affirmatively, an accelerator transmuting waste would not constitute a "production facility" subject to NRC licensing under Part 50. Even though the regulatory definition looked as though it might encompass accelerators, it had been written more expansively than the statutory definition in order to encompass reprocessing facilities that, although they do not produce special nuclear material anew, do separate it into a usable form and therefore could be said to "produce" it. The AEA defines a utilization facility as "any equipment or device, except an atomic weapon, determined by rule of the Commission to be capable of making use of special nuclear material in such quantity as to be of significance to the common defense and security, or in such manner as to affect the health and safety of the public, or peculiarly adapted for making use of atomic energy in such quantity as to be of significance to the common defense and security, or in such manner as to affect the health and safety of the public …." NRC regulations, however, currently limit the definition of a utilization facility to "any nuclear reactor other than one designed or used primarily for the formation of plutonium or 233U." Whether an accelerator used to transmute waste would be considered a utilization facility hinges on whether neutron bombardment of the waste material would produce heat used to generate power. If it would not—even if heat were produced elsewhere in the accelerator transmutation system and were used to produce power—the accelerator would not constitute a utilization facility. Even though an accelerator might not, under current law, be deemed either a production or utilization facility, it would still most likely require a materials license under 10CFR70. This license might have to be issued by NRC if the quantities of material to be handled at the facility would be greater than critical mass. Otherwise, it could be issued by an agreement state. Congress might also legislate a requirement that an NRC license be obtained for the construction and operation of an accelerator used to transmute waste. In the Energy Reorganization Act of 1974, for example, Congress provided NRC with licensing and regulating authority over liquid-metal fast breeder reactors, other new demonstration reactors, facilities used to store HLW resulting from NRC-licensed activities, and facilities used for long-term storage of defense HLW. Waste Storage and Disposal This section discusses the regulatory aspects of storing spent nuclear fuels and disposing of nuclear fuel-cycle wastes. Spent-Fuel Storage (pool). The vast majority of civilian spent nuclear fuel is stored in pools at reactors. The NRC licenses the construction and operation of these fuel pools as part of the normal (e.g., 10CFR50) licensing process for reactors. An independent fuel pool would be licensed un-
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Nuclear Wastes: Technologies for Separations and Transmutation der 10CFR72 (Licensing Requirements for the Independent Storage of Spent Nuclear Fuel and High-Level Waste). Spent-Fuel Storage (dry cask). DOE is seeking to site and construct a monitored retrievable storage facility for the receipt and storage of spent nuclear fuel from NRC-licensed reactors. Under the Energy Reorganization Act, section 202(3), such a facility would be subject to NRC licensing under 10CFR72. The same regulations would apply to development of dry-cask storage at an S&T facility built in conjunction with S&T facilities. While EPA has developed standards for the protection of the environment from stored high-level and TRU wastes, the standards are currently written to apply to such wastes only when at a repository site (40CFR191). Geologic Repository (high-level and TRU Wastes). Development and operation of one or more repositories for the disposal of HLW are governed by the Nuclear Waste Policy Act (NWPA). The law, as amended in 1987, directs DOE to investigate the site identified at Yucca Mountain, Nevada, for the possible development of a repository. After site investigation, the Secretary of Energy may recommend approval of the site to the President, who, in turn, may make a formal recommendation of approval to Congress. While Nevada may then formally veto this determination, the law provides that Congress can override the state's decision. If site approval is sustained by Congress, the NRC would consider DOE's plans for the development and operation of the repository in a formal licensing process. The licensing process would be governed by specific NRC regulations (40CFR191). The NRC requirements are dictated, to a large extent, by standards developed by EPA in 1985 setting limits on releases of radioactivity to the general environment, including groundwater, and on human exposure (40CFR191). The First Circuit Court of Appeals vacated the standards in 1987 because of inconsistencies with the Safe Drinking Water Act in the protection afforded by the standards to underground sources of drinking water and inadequacies in the standard governing individual exposures. Five years after the court's decision, EPA has not succeeded in issuing revised standards for a repository that might be established at Yucca Mountain because of several controversial issues. These include, for example, the release limit for 14C, how inadvertent human intrusion should be analyzed, and the level of certainty required for a determination of compliance. In 1992, Congress directed a National Research Council study to provide recommendations to the EPA concerning the technical basis for health-based standards. Details are given in Chapter 2. Low-Level Waste Disposal. Low-level wastes from fuel-cycle facilities are generally regulated by NRC and agreement states under 10CFR61. These regulations divide LLW into three classes, depending on radioactivity and half-lives (10CFR61.10-61.31). They also set out detailed requirements for licensing LLW disposal sites. However, NRC does not usually regulate accelerator-produced radioactive waste (activation products, etc.) because such waste generally does not meet the definition of ''by-product material" under the AEA, that is, "radioactive material … yielded in or made radioactive by exposure to the radiation incident to the process of producing or utilizing special nuclear material … "(USC 42 6901-6992k). If it were determined that the accelerator itself constituted a production or utilization facility under the AEA, any accelerator-produced waste would constitute by-product material. If it were agreed that the accelerator were not such a facility, then the material would be exempt from NRC regulation. EPA has proposed to regulate accelerator-produced wastes but has not succeeded in developing final regulations. (A handful of states have developed regulations for non-AEA wastes, but these do not appear to cover accelerator-produced wastes.) The Regulatory Role of the States Any assessment of the impact of environmental statutes and regulations must also take into account the increasingly important role of state governments. For example, state and local requirements govern several facets of uranium-mining operations, including land disturbance and groundwater pollution caused by uranium exploration activities and mined land reclamation. With the new federalism of the 1980s, many of the states have assumed leadership roles not only in the development of their own environmental statutes and regulations, but also in the implementation of the major federal environmental laws. In fact, through the process of EPA state agreements, the majority of the states have been delegated the authority for the permitting and enforcement activities for the major federal laws, including the Resource Conservation and Recovery Act, the Clean Water Act, and the Clean Air Act. In addition to the federal statutes, laws and regulatory requirements that could affect the siting and operation of DOE waste-management facilities have also been developed by the majority of states. These approaches may parallel federal statutes but often include additional requirements concerning waste storage and repository siting; worker and community "right-to-know" waste tracking; air, water, and waste characteristics, quantities, and radioactivity limitations; and reporting. An inventory of all such state and local regulatory requirements is beyond the scope of this report; however, an evaluation of these additional requirements is an essential prerequisite for the development of any technology for waste treatment or storage. The tripartite agreements developed at several DOE fa-
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Nuclear Wastes: Technologies for Separations and Transmutation cilities illustrate the current trend toward shared decision-making. The increased involvement of the states in waste management decisions brings with it an increasing need to address public concerns about risks. Public opinion on nuclear waste and other environmental issues has had a profound impact on the political process on the state and local levels. Elected officials must be responsive to local concerns about environmental and health risks, so state policies are more likely than federal statutes to require extensive evaluation and control of actual and perceived risks. Conclusions If one accepts the eventual need for reprocessing and recycling as a part of a sustainable supply of nuclear power, then challenging regulatory and licensing issues will inevitably have to be faced. For the most part, the fundamental federal regulatory framework needed to license the facilities required to implement S&T technology exists. Most of the fuel-cycle operations involved in S&T would be governed by federal regulations that are established and familiar. There are two notable exceptions to the preceding statement, however. First, the applicability of existing regulations to accelerator-based transmutation devices with closely coupled continuous fuel reprocessing is very unclear. Second, one or more major generic environmental impact statements would be required before reprocessing could begin. In addition, state and local governments are becoming increasingly involved in regulatory activities, both by enforcing federal regulations and by applying additional requirements. This introduces additional uncertainties into the future regulatory environment for S&T facility deployment. For instance, neither the underlying standard nor the regulations relevant to a potential repository at Yucca Mountain is final. It is very difficult to predict what the regulatory and licensing situation will be at the time when S&T technology might be implemented. If the major changes in licensing and regulation experienced over the last 15 years are a harbinger of the future, the situation is likely to be radically different from what exists now. RESEARCH AND DEVELOPMENT NEEDS This report addresses application of separations and transmutation (S&T) technology to two distinct waste streams: civilian reactor spent fuels and neutralized defense high-level waste. At present, transmutation technology is not developed to the point at which it could be applied immediately and directly to either waste stream. Separations technology is better developed, but important advances are still possible with further research and development. As a consequence, if S&T is to be implemented, a research and development program will be required to provide the needed technology. The committee is of the view that a sustained, carefully focused program of research and development emphasizing advanced separation technologies should provide a sound basis for future decisions on nuclear waste S&T. Following successful laboratory-scale development, engineering pilot-scale demonstration would be necessary. Civilian Reactor Spent Fuels It should be recognized at the outset that S&T (i.e., enhanced recovery and destruction of selected radionuclides) is inextricably intertwined with standard spent-fuel reprocessing. As a result, the discussion of research and development needs involves substantial aspects of current reprocessing technology. There is no immediate need to deploy S&T technology—primarily because the long duration of the repository project and the economics of reprocessing are unfavorable in the current era of low-cost uranium and enrichment—so a research and development program cannot be viewed as urgent. For the near future in the United States, S&T is best regarded as a contingency option. (Present U.S. policy continues to hold that spent reactor fuel will not be reprocessed.) On the other hand, implementation of reprocessing/S&T might become desirable under a variety of situations, ranging from a change in the economic viability of actinide recycling to being required to facilitate establishment of a repository, to ameliorating the climatic impacts of other energy production technologies. Because the time required to develop S&T technology is long compared to the time over which we can foresee the degree to which it would be needed, it is desirable to continue to develop S&T technology until such time as a firm determination of need or the lack thereof can be made. Justifications for sustaining a modest level of research and development on S&T technology include: the inefficiency of ceasing research and development now, and then restarting it as a part of a crash program in the future; the desirability of maintaining a base program on fast reactors and actinide recycling in the United States, so that we will have the expertise and credibility required to be effectively involved in international nonproliferation activities and also have access to related technology developments in other countries; and the need to develop improved technologies for transmuters and reprocessing so as to improve safety, economics, and proliferation resistance if and when needed. Continued research and development in S&T will pro-
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Nuclear Wastes: Technologies for Separations and Transmutation vide a basis for making sound decisions at a later time when S&T might appear to merit reconsideration. In general, continuous processes (e.g., solvent extraction) are to be preferred over semicontinuous processes (e.g., ion exchange), which in turn are preferred over batch processes (e.g., electrorefining) because of increased efficiency and reliability. Inorganic reagents are preferable to organic reagents because of their greater stability, although waste volume needs to be taken into account if the ion exchange medium becomes a waste because of degraded performance. As implied in the earlier discussion of priorities, the highest priority for transmuters clearly belongs to LWRs for the initial phases of S&T, followed by LMRs (possibly with some LWR component) for the longer-term transmutation of actinides. Other transmuters do not appear to offer advantages commensurate with the development risks and costs, although limited support of these devices for S&T purposes might be warranted if the base development program were to be funded for other reasons. The committee believes that research and development activities should remain at the minimum scale consistent with maintaining the ability to obtain results needed for technology assessment and for expeditious implementation in an operating facility. In general, this minimum scale will involve a sequence of activities at the cold bench, hot bench, cold engineering (or pilot plant), and hot engineering (or pilot plant) scales. If demonstration at existing facilities or pilot-scale work will not suffice, transmuters may require an operating demonstration facility and technology assessment to reduce the number of demonstrations to a minimum. However, it is to be emphasized that use of actual feed materials is imperative in the research and development phase. Neutralized Defense High-Level Waste In the case of neutralized defense HLW, the forces driving S&T research and development are very different from those related to spent reactor fuel. These diluted wastes contain small amounts of long-lived species relative to those in spent fuel, and the volume of the wastes is very large. The objective for defense wastes is the use of S&T technology to reduce the volume of HLW by processing the waste into as small a volume of HLW and as large a volume of LLW as are economically feasible within the balance between separations and disposal costs. These wastes are primarily composed of common chemicals that do not need to be treated as HLW (i.e., vitrified and sent to a repository). The removal of these chemicals could reduce the volume of HLW by factors of 5 to 200, saving billions of dollars with little change in risk. Tank-waste remediation is already beginning at Hanford and Savannah River, with existing technologies, but the remediation programs will take decades and therefore could benefit from a parallel program of research and development. The committee notes that research and development for defense HLW should not include transmutation of long-lived radionuclides. The amount of radionuclides relative to that in LWR spent fuel is simply too small to justify such an effort. Research and development for Handford, Savannah River, and Oak Ridge can be coordinated and shared, and the longer-term research component should benefit all those sites. In general, only aqueous processes should be considered for processing defense HLW. The range and merit of the various alternative processes are discussed in detail in Chapter 3. While small, specific problems may require other classes of processes, the genesis and composition of these wastes dictate an aqueous approach (with, perhaps, the exception of the wastes at Idaho National Engineering Laboratory). As with spent-fuel processing, continuous processes are to be preferred over semicontinuous, which in turn are preferable to batch processes. In any case, it is imperative that the normal technology development sequence (cold/hot bench, cold/hot pilot plant) be followed, except in cases where there are clear and immediate safety hazards or severe deterioration of containment. To do otherwise entails large economic and credibility risks that should be viewed as unacceptable. REFERENCES Alexander, C. W., and A. G. Croff. 1980. Actinide Partitioning-Transmutation Program Final Report. IV. Miscellaneous Aspects. ORNL/TM-6984. Oak Ridge, Tenn.: Oak Ridge National Laboratory. Blix, H. 1992. Non-proliferation and verification in the 1990s: Securing the future. 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Representative terms from entire chapter: