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The difficulties of disposition of surplus plutonium from dismantled nuclear weapons are compounded by continued reprocessing of civilian spent fuel in Russia, France, Japan, Britain, and India. The governments of these countries are wedded to civilian plutonium separation as an important long-term component of energy programs. They are very unlikely in the near-term to give up these programs unless their energy concerns are addressed. Yet, if reprocessing, whether military or civilian, continues, disposition decisions on U.S. surplus military plutonium alone will not fundamentally change the global security picture. The separation and circulation of civilian plutonium will, in the coming decades, far exceed the approximately 250 metric tons of military plutonium in the world. Moreover, reprocessing civilian spent fuel is continuing in Russia; until it is halted, the security concerns in relation to weapons-usable materials associated with the state of the economy and society there cannot be resolved. Therefore, policies directed at achieving a universal but interim halt to reprocessing are essential so that the plutonium problem is not being aggravated while long-term energy and security issues are sorted out.
No country now engaged in civilian plutonium production is likely to stop even on an interim basis without vigorous U.S. leadership. A clear and formal declaration by the U.S. government that plutonium is a security, environmental, and economic liability should be the starting point of such leadership. The text of a letter sent by 43 organizations and individuals to President Clinton on October 19, 1994 requesting such a declaration is attached as Appendix A to this report.
As we discussed in Chapter 3, the U.S., were it on its own, could more freely consider pursuing the MOX option for putting excess military plutonium in proliferation-resistant form. However, the main threat over the next many years does not come from excess U.S. military plutonium, but from the situation in the former Soviet Union. Thus, in our analysis, a MOX option should be ruled out for the U.S. so that it can play the leading role that is needed to stop civilian reprocessing as well as military plutonium production throughout the world.
The only other option that has a chance of accomplishing the immobilization of plutonium into proliferation-resistant form within a reasonable time-frame is vitrification. As discussed in Chapters 4 and 5, there are four broad technical options for plutonium vitrification:
Plutonium processed by the last three options would not meet the spent fuel standard, but, as we have discussed in Chapter 4, the third and fourth options could approximate it on most counts, depending on the material(s) chosen as additives. The last two options may be combined.
It has generally been assumed that the spent fuel standard should be adopted for plutonium disposition probably because it is the most attractive according to certain non-proliferation criteria, in particular, the difficulty of re-extraction of plutonium and the resistance to theft that unshielded spent fuel provides. (117) It is also the strictest practical standard since civilian spent fuel has a large amount of plutonium in it. Processing excess military plutonium to a more stringent standard of re-extraction is therefore seen as a waste of money, given that plutonium could be extracted from civilian spent fuel. It is also generally assumed that mixing plutonium and fission products in the body of the glass is the way that the spent fuel standard should be achieved, if vitrification is the chosen disposition option.
These assumptions need to be refined for a number of reasons. First, gamma-emitting fission products, notably cesium-137, that give spent fuel its proliferation resistance have far shorter-half-lives than plutonium. (The half-life of cesium-137 is about 30 years compared to 24,000 years for plutonium-239.) Therefore, plutonium processed according to the spent fuel standard becomes less resistant to proliferation over time. In the course of a few hundred years, it will come to resemble vitrification of plutonium alone, which is the least strict of the vitrification options we have discussed in this book. Vitrification of plutonium with a non-radioactive chemical analog would provide a somewhat lower but much more durable level of proliferation resistance. The same is true of vitrification with uranium-238 or thorium-232, since both these isotopes have far longer half-lives than the plutonium isotopes in civilian or military plutonium.
Second. vitrifying plutonium mixed with fission products in the U.S. is likely to take long, since existing vitrification plants may be unsuitable for this purpose, as we have already discussed. Therefore, this option is unlikely to be accomplished as rapidly as would be desirable for non-proliferation reasons.
Finally, the spent fuel standard possesses a political defect if it is accomplished by mixing fission products into the glass. It is highly unlikely to be accepted by the countries that have spent and are spending large amounts of money for reprocessing civilian spent fuel. Even if the United States goes ahead and vitrifies its plutonium to this standard by mixing it with fission products, it is unlikely to persuade Russia, France, Japan, Britain, and India to do likewise. A lower level of re-extraction cost may be necessary to persuade these countries to halt reprocessing on an interim basis. Another way of stating this problem is that the spent fuel standard is irrelevant at the governmental level in countries that are now reprocessing. Putting some plutonium into spent fuel or vitrified glass would reduce proliferation threats only for a brief period if plutonium separation continues. The challenge therefore is to find a plutonium disposition option that will provide as high a resistance to theft as spent fuel for sub-national groups, and also pose great challenges for plutonium re-extraction for the same groups. So far as countries that now reprocess or that own separated plutonium, the main tasks are to persuade them to stop reprocessing and to ensure and verify that already separated plutonium is not used to make nuclear weapons.
These goals can be accomplished with the appropriate policies. Even countries such as Russia and Japan that are vigorous proponents of civilian reprocessing recognize four things, even if they do not often do so publicly:
Given this common ground, it may be advantageous to consider plutonium vitrification options where the level of effort of re-extraction is somewhat lower than the spent fuel standard for governments that are reprocessing today, both in terms of the expenditure and time, but still very high for sub-national groups. Evidently, this means that there is a corresponding decrease in the technical barrier to re-use by governments. This problem can be mitigated by safeguards and verification measures, which are in any case necessary for civilian and military separated plutonium. These measures should be buttressed by a multilateral agreement that plutonium, once declared surplus to national security, will never be used in weapons.
The barrier to theft of plutonium and hence to use by sub-national groups can be made high by making the canister containing the vitrified plutonium highly radioactive. In fact the level of resistance to theft provided by such canisters would be comparable to unshielded spent fuel ready for dry storage and far higher than that of spent fuel stored shielded casks such as those that are used for spent fuel transportation. Such casks are now under consideration in the United States for all spent fuel. The technical level of difficulty for re-extraction would be relatively high for sub-national groups, especially since remote handling would be required to remove the plutonium-containing glass from the highly radioactive canister. Beyond this step, vitrification with actinides or rare earths would provide an intermediate level of difficulty of re-extraction.
This complex of measures would allow governments that own plutonium today to recover it in the future, but make it very difficult for sub-national groups to do so even if diversion of the glass logs occurred. Thus, it would be less difficult to persuade governments that still see plutonium as a long-term energy asset that all excess plutonium, including civilian separated plutonium, should be vitrified now to reduce security risks, while keeping open the option of using it in the future should the need arise.
Our reasoning is similar to that which the NAS used in recommending further work on the deep borehole disposition option for excess military plutonium. The deep boreholes in which plutonium would be disposed of would be 2,000 to 4,000 meters deep. Plutonium emplaced at such depths would be far less accessible than that disposed of in geologic repositories, for which typical proposed depths are up to about 1,000 meters. The NAS study recommended further research on this option as a possible alternative to vitrification of plutonium and/or use of MOX fuel, even though it does not meet the spent fuel standard. This is because deep borehole is a disposition option that presents an intermediate level of difficulty of recovery of plutonium for governments but a high-level of difficulty for sub-national groups. According to the NAS, this potential for recovery may be an advantage with respect to governments, like Russia, that believe that plutonium may one day be a valuable and economical energy resource. (118)
The same reasoning leads us to conclude that an intermediate level of difficulty of re-extraction could help put existing separated plutonium in non-weapons-usable form. It could also help convince at least some of the civilian plutonium separating countries to temporarily halt reprocessing until security issues surrounding plutonium can be resolved in a way that greatly reduces the immediate and short-term dangers on as universal a basis as can be achieved.
It may be necessary to offer all countries that own civilian plutonium, but especially Russia and India, a guarantee that grants for plutonium re-extraction would be available should the need arise for using plutonium as an energy source and should it become economical relative to uranium use. Measures to discourage such extraction would also be built into such financial arrangements by holding some of the LEU to be produced by blending down HEU from dismantled weapons as a reserve for use in reactors that would otherwise be fueled with plutonium or with MOX fuel. This LEU reserve could play a global role similar to the domestic role served by the U.S. Strategic Petroleum Reserve. The LEU reserve could be held in part nationally, in part bilaterally (U.S.-Russia), and in part multi-laterally.
We recognize that the proliferation resistance properties of plutonium vitrified with fission products are in some respects stronger than those of plutonium vitrified with actinides or rare earths. We are not advocating that the spent fuel standard be abandoned as an objective. Rather, its refinement so as to accommodate broader goals of putting all weapons-usable plutonium into non-weapons-usable forms is needed. To this end, we strongly urge that vitrification of plutonium with rare earths and actinides should be investigated and the pilot plants should be built.
Reducing the difficulty of re-extraction need not mean lowering the barriers to theft. The difficulty of theft depends on a number of factors, of which a high external gamma radiation field is one of the most important. There are a number of ways in which high external gamma radiation fields can be created to deter theft without mixing plutonium with fission products. One way would be to put plutonium vitrified with rare earths into cesium-137-laced radioactive containers that are manufactured separately. Alternatively, a small container with cesium-137 or a mix of calcined fission products in it could be placed in the canister at a time after plutonium-laden glass has been poured into it. There are some advantages to the former approach. First, the work with gamma emitting fission products can be done entirely separately from the vitrification plant. Second, the canister containing vitrified plutonium can be sealed shortly after the glass is poured. Third, the difficulty of re-extraction may be lower once the glass is removed from the canister. Therefore, this would be more attractive to plutonium-owning countries that regard plutonium as an energy asset, but resistance to theft would still be as high as with the spent fuel standard.
Combining the canister rather than the glass with one or more fission products means that hot-cell processing of gamma-emitting radioactive materials can be done more slowly or even separately from plutonium vitrification. Thereby achieving the spent fuel standard is made compatible with putting plutonium into a non-weapons-usable form as rapidly as possible. Further, the amount of fission products to achieve a specified gamma radiation field will be far lower, as we have discussed in chapter 4.
Vitrifying plutonium with a rare earth or actinide and putting gamma-emitting radioactive materials in the canister appears to be the option that best combines various disposition goals. We recommend that DOE commission a feasibility study and appropriate laboratory work on this option in parallel with the pilot plants mentioned above.
Highly Enriched Uranium Disposition Policy
There are about 2,300 metric tons of HEU in the world today, almost all of it in the United States and the former Soviet Union. As we have discussed, about 1,000 metric tons or more of this could become an official surplus as existing arms reduction agreements are implemented over the next decade. It would appear at first that the blending down of HEU to LEU for use in civilian reactors would be the most straightforward way to reduce the attendant security risks. However, as we have noted, the capacity for this blending down does not yet exist in the United States.
The U.S.-Russian agreement, signed in early 1993, will be implemented very slowly, even after blending down actually begins. In each of the first five years, only 10 metric tons of HEU of 90 percent enrichment or greater are required to be blended down, with the rate going up to 30 metric tons per year in the fifteen years after that. At these rates, only 200 metric tons of HEU would have been blended down a decade after the implementation begins. The entire amount will have been blended down in 20 years.
The security threats arising from potential black market sales of HEU may be greater than those arising from plutonium because HEU can be fashioned into weapons of both implosion and "gun-type" designs, while plutonium warheads must be made with an implosion design. Therefore, bilateral or multilateral control, verification of stocks, and adequate materials accounting are all needed.
The large delays in converting HEU into LEU could be mitigated by two policy responses, in addition to the storage and verification arrangements that are needed in any case. The first would be to build new capacity for blending down HEU as rapidly as compatible with environmental and health considerations. The second would be to vitrify a portion of the HEU. The objective of vitrification would be to quickly raise a barrier to proliferation while leaving open the possibility of recovering the HEU and blending it down into LEU for use as fuel. It may be possible to accomplish vitrification on a faster time-scale than blending down might allow. However, vitrification could make LEU derived from HEU uneconomical relative to LEU from newly mined uranium. This is an issue that needs to be addressed prior to a decision on a policy for vitrifying HEU.
Finally, it is relevant to note in this context that HEU does not entirely cease to be a security problem once it has been blended down into LEU. This conversion only raises a barrier to proliferation. Specifically, LEU can be re-enriched to HEU and used for nuclear weapons. If the enrichment process involves the use of gas centrifuge plants, which are in commercial use both in western Europe and in Russia. The detection of re-enrichment at these and any similar plants built in the future will be difficult without extensive new safeguards. It is therefore essential that verification of LEU stocks and more importantly of enrichment facilities not now under IAEA safeguards be established so as to make its re-enrichment very difficult. This adds to the need to examine vitrification of HEU as at least a partial disposition option.
In sum, while there is a theoretical solution to the problem of surplus HEU in blending it down to LEU, the practical situation is such that the security threat from HEU will persist, even if we restrict attention to the partial stocks that may be declared surplus over the next decade. Of course, the actual magnitude of the threat is larger, and covers the whole amount (as it does with plutonium).
The question of what should be done with the LEU blended down from HEU is also not as straightforward as might first appear. First, there are commercial pressures to keep the LEU in reserve so as to protect the financial interests of existing commercial producers of uranium as well providers of enrichment services.
Commercial considerations should not be a prime component of the decision to withhold the LEU from the market. However, they could be partly compatible with security criteria. As we have discussed, a portion the LEU produced from HEU could be used to build up a stock of nuclear power plant fuel as part of a guarantee to those countries that stop reprocessing spent fuel that they will not lack for fuel, should uranium prices escalate in a manner that is not now anticipated. The strategic stock of LEU could also be used as a modest lever to hold uranium prices to levels that would discourage commercial reprocessing. The first batches of LEU produced by blending down HEU could be devoted to creating such a strategic LEU stock. Any vitrified HEU would also, in effect, serve as a strategic stock. The issue of the size of the stock of LEU required for an effective strategic reserve needs to be studied.
Institutional Issues
It is now at least routinely acknowledged that operations in the nuclear weapons complex must be carried out in conformity with environmental, safety, and health laws and regulations, and with the full participation of the affected communities and other "stakeholders" such as workers. There have also been real and positive changes on a number of other fronts in the Department of Energy, notably at the national level. There are increased opportunities for public participation. Site Specific Advisory Boards are being created or have been created at most nuclear weapons plant sites. Secretary of Energy Hazel O'Leary has released large amounts of data and documents in an unprecedented openness initiative, despite some opposition from the Pentagon. The DOE has also taken the lead in ending funding of the ALMR, a reactor that could produce plutonium, and hence pose a problem from a proliferation standpoint.
This real progress has not yet gone far enough however. Field and contractor operations and decision-making are not carried out with the openness that is needed; nor is there a sufficient, routine concern for the protection of health and the environment. Spending on weapons continues to be very high, though no weapons are being made. Nuclear weapons testing is re-appearing in new, small-scale disguises. Old technologies that were designated for nuclear weapons production or nuclear power development suddenly appear as clean-up or disposition technologies or both. Most recently, pyroprocessing technology, detached from the now defunct Advanced Liquid Metal Reactor, has made an appearance on the plutonium disposition scene in a forceful manner. The DOE has recently "reprogrammed" money to increase funding of pyroprocessing. (119) While this is ostensibly for examining this technology for plutonium disposition, it also sustains the crucial research aspects of pyroprocessing as a reprocessing complement to the ALMR, which is an advanced plutonium breeder reactor. This is counterproductive for non-proliferation goals. In short, the hold of nuclear weapons makers and contractors on government policy is still strong.
We have already noted an example of the violation of storage regulations for HEU at Oak Ridge. Incineration is still the basic method of handling mixed radioactive and non-radioactive hazardous wastes. The classification of radioactive waste is still based on a scheme that is not systematically related to the longevity and hazard of the waste. The DOE has yet to submit itself to independent regulation, despite some progress towards creating a framework to achieve this goal. The durability of the progress that has been made is also an open question. In sum, it is not clear that the DOE (the agency whose main mission it was to build bombs), is well-suited to dismantle them and manage the materials. That was the central thrust of the analysis of institutional problems made by the OTA in its 1993 report, which concluded that "U.S. dismantlement and materials management efforts have lacked focus, direction, and coordination." (120) The OTA also concluded that a new office within the DOE or an entirely new agency of government might be needed to manage the problems of the post-Cold War era arising from nuclear weapons dismantlement and materials management. (121)
A new Office of Fissile Materials Disposition was created in January 1994. It is dedicated to disposition issues; it is too early to tell whether this office will be able inspire the kind of work that its mission requires. Further, there is no agreement between the DOE and the Pentagon on crucial disposition issues, such as whether and how much plutonium should be declared a liability, and on how open the government should be with the people of the United States.
It is clear that the vital need to put weapons-usable nuclear materials into non-weapons-usable forms cannot be successfully met, much less with the speed that is desirable from a security standpoint, until these basic institutional issues are resolved. Continued pressure from the affected communities will be central to their resolution.
Public Participation
Successful implementation of plutonium and HEU disposition policy will need the full involvement of the affected communities, especially since speed of implementation is a basic security need. The poor record on health and environmental protection of the DOE and its predecessor agencies has engendered a profound public distrust that has only begun to be remedied by the openness initiatives of recent years. It is more than likely that any closed process will lead to delays and perhaps also to inappropriate choices of technology. The discussion below is specific to the process for building pilot plants for plutonium vitrification, but the spirit of the comments regarding openness and public participation applies equally well to HEU disposition.
A principal recommendation of this book is that three or four pilot plants for plutonium vitrification should be built. One reason for the emphasis on pilot plants is that the DOE needs to gain operational experience with the technology in order to prepare a sound environmental impact statement on vitrification that would result in the selection of the best way(s) to vitrify various forms of plutonium and the best way to achieve non-proliferation goals in a manner compatible with health and environmental protection.
The pilot plants for vitrifying plutonium should be small enough that they will allow operational experience to be accumulated without risk of severe accidents but large enough that full-scale plants could be built and operated with confidence based on that experience. In our view, plants meeting these criteria would be large enough that a very open process for setting them up is necessary. On the other hand, it should be possible to design them so that they are small enough to obviate the need for formal environmental impact statements or environmental assessments under the National Environmental Policy Act.
The DOE needs to open up the process for selecting vendors for vitrification technologies so as to include its own laboratories, U.S. corporations that have not been traditional DOE vendors, as well as foreign corporations that have relevant expertise and experience. Further, as we have noted, the DOE should seek to involve Russian institutions at the pilot plant stage so that full-scale plants can be rapidly built in Russia once there is agreement on a disposition method for Russian plutonium. Moreover, the Russian nuclear establishment has considerable operational experience with vitrification and this may help in designing and building the pilot plants.
A closed process of vendor selection would be highly undesirable. The DOE's record in successfully opening major new facilities has been very poor since its creation as a cabinet-level department in 1977. An open process for setting goals for the project, the criteria for vendor selection, and the selection of the vendors is necessary for the critical work of developing plutonium vitrification technology and implementing it in a manner than joins deliberate speed with measures for achieving the protection of health and the environment.
One approach to building plutonium vitrification pilot plants would be for the DOE to hold a competition seeking bids for designing, building, and operating them. The DOE would specify the goals of the project -- namely to test and assess for the environmental, safety, health, and economic standpoints of various ways to vitrify plutonium -- and the criteria by which these goals would be evaluated. Bids that include qualified Russian collaborators would be encouraged. The proposals would be required to include an environmental and health analysis of the impact of the pilot plants, the employment levels expected, the skills needed, and a summary of the bidders' health and environmental track record. All bids would be made public after the closing date and open discussions would be held at the proposed pilot plant sites on their relative merits. This would aid in the selection of the best proposals. Further, by involving the affected communities, the DOE can ensure their support for the full-scale plutonium vitrification when it is carried out. We suggest that the competition be started in early 1995 and that the selection process of the pilot plant vendors be completed by the end of 1995 or early 1996.
Long-term Policy Issues
Whether plutonium is vitrified or burned in reactors without reprocessing, a large amount of it will remain for tens of thousands of years. Further, there are large amounts of plutonium in civilian spent fuel as well as in separated plutonium from such spent fuel. These sources of plutonium will constitute a threat to the security of future generations that will endure for thousands of years. As we have discussed, the threat from spent fuel will increase, since the decay of intense gamma emitting isotopes, especially cesium-137, in a few hundred years will make it easier to recover plutonium from spent fuel or glass logs containing high-level waste.
It has generally been assumed that this threat will be greatly reduced by disposing of spent fuel and vitrified waste in a geologic repository. This would increase the costs of plutonium recovery so greatly that it would be more costly to recover spent fuel or vitrified waste from a repository and reprocess it than to derive plutonium from new reactors and reprocessing plants. That should, in fact, be one of the design objectives of a repository. (122)
This theoretical scheme is flawed by one crucial reality. No country has as yet been able to successfully site a geologic repository, though several have been pursuing such a course for decades. There are many reasons for the delays and failures.(123) One principal issue has been that the search for a repository has been bound up in a conflict of interest. The very institutions that have a financial and military interests in nuclear power and nuclear weapons (which together generate most of these wastes) are responsible for or intimately involved in repository selection. Further, we have no institutional experience and not enough scientific knowledge (by a long shot) to predict with confidence the environmental threats that such disposal will pose over hundreds of millennia. The public is rightly skeptical.
If separated plutonium is managed in the interim according to the spent fuel standard, the long-term issues for its disposal are essentially the same as those that arise for unreprocessed spent fuel from civilian power plants. We have already briefly discussed issues of plutonium disposition as they relate to possible repository disposal in the U.S. in Chapter 6.
Essentially complete elimination of plutonium can only be accomplished by two methods. One is to simply wait until the natural radioactive decay of its nuclei have converted it to uranium-235. Since the half-life of plutonium is over 24,000 years, this period of waiting is far longer than the longevity of any human institutions. The other approach is to transmute plutonium using some technique to bombard its nuclei and split them into fission products. Most of these fission products are radioactive; most have half-lives of a few decades or less, but some like technetium-99 and cesium-135 have half-lives that are very long.
So far, the approaches that have been considered for complete transmutation of plutonium in major recent studies have considered only reactor options with some associated reprocessing technology. The two most commonly considered technologies in this category are the Advanced Liquid Metal Reactor (ALMR), which can also be used to breed plutonium, and a proton accelerator combined with a sub-critical reactor and reprocessing, proposed by Los Alamos National Laboratory. Both these technologies must be rejected on proliferation grounds. The U.S. Congress, at DOE's request, has eliminated funding for the ALMR for 1995, though not for the reprocessing technology, called pyroprocessing, associated with it.
One approach that can be used for separated plutonium that does not involve the use of nuclear reactors or reprocessing, but may still result in the elimination of plutonium, is fission using gamma rays. Its feasibility for plutonium disposition has not yet been examined, so far as we have been able to determine. The method involves the fission of plutonium nuclei by the use of high energy gamma rays, which consist of high-energy electromagnetic radiation. The process is called "photofission" because the fission is induced by photons, which are quanta of electromagnetic energy. Other heavy nuclei can also be split by photofission.
A specific spectrum of gamma rays with photons in the energy range of 10 to 15 MeV has a particularly high chance of producing fission in heavy nuclei. This spectrum is called the "giant resonance region" for inducing photofission. Photons of these energies can be produced using an electron accelerator, which is a very well understood technology. The radiation from the stopping (or braking) of high energy electrons (called "bremstrahlung radiation") can be tailored to produce photons in approximately the required spectrum. The photons would induce fission in a plutonium target.
The heat from the braking of the electrons as well as from photofission would have to be carried away by a coolant. This creates the possibility that some of it could be recovered in order to generate electricity. Whether such heat recovery for electricity production is desirable is one of the many questions to be addressed by a feasibility study examining photofission as a long-term disposition option for already separated plutonium.
While the physics of such a scheme is understood, it would be an immensely difficult and complex engineering challenge. During the 1970s, the method was briefly considered for dealing with spent fuel. However, it was rejected because the energy needed to induce photofission to get rid of the long-lived heavy elements would be greater than the energy produced from the fuel in the nuclear reactor. (124) Further, photofission would require that the elements to be fissioned be separated from spent fuel, that is, it would require reprocessing. Thus, the approach also is unacceptable for dealing with spent fuel on proliferation grounds.
However, if plutonium is not mixed with fission products, then it can, in principle, be made into targets that are suitable for photofission. The energy use as well as the capital and operating costs of fissioning plutonium completely in this way are likely to be very high. Since the plutonium would be fissioned, the problems of disposing of highly radioactive fission products would also exist with photofission as with all others that depend on fission for plutonium transmutation. The interaction of the photons with a mixture of fission products also needs to be investigated. Further, fission produces neutrons; these neutrons would produce activation products, rendering radioactive a portion of the structure of the devices needed for transmutation. Thus, photofission does not represent a solution to the plutonium disposition problem in the sense of promising something satisfactory without serious long-term financial and environmental costs.
Photofission, if feasible, may offer the potential for complete transmutation of already separated plutonium. But there are many technical unknowns. For instance, its technical feasibility without resorting to some form of reprocessing technology will likely depend on whether appropriate targets can be fabricated that would hold up to the intense radiation and heat until essentially all the plutonium has been fissioned. It is unclear at present whether this can be done in practice.
The only other approach that could get rid of separated plutonium without reprocessing is to shoot it into the sun. While at present both costs and dangers of this approach are immense, we believe this also deserves a more careful feasibility study.
Neither space disposal nor photofission can deal with the problem of plutonium in spent fuel, unless it is first reprocessed. Therefore, when examined from the perspective of the overall problem of plutonium elimination, they do not represent solutions. Whether such technologies would be worthwhile at all just for disposing of already separated plutonium is an open question. We believe that both approaches deserve serious feasibility studies so that we may have a basis to decide whether some research and development of one or both of them would be worthwhile.
The future of security and environmental issues arising from the creation of plutonium is bound up with nuclear power production, since essentially all nuclear power plants produce large quantities of plutonium as a normal part of their operation. The only exceptions to this are reactors that use HEU as fuel, but this fuel is itself a proliferation problem. Therefore, if we are to make an attempt to definitively deal with the threats arising from the existence of weapons-usable fissile materials, we must confront the central issue of what energy sources the world will rely on for the long-term. Our final recommendation is therefore that the use of nuclear power should be more carefully evaluated in light of the long-term proliferation problems posed by the very existence of large and increasing quantities of plutonium in spent fuel.
118.NAS 1994, pp. 196-199.
119. Letter from Joseph Vivon, DOE Chief Financial Officer to Congressman Tom Bevill, Chairman, House Subcommittee on Energy and Water Development, Committee on Appropriations, September 23, 1994.
120.OTA 1993, p. 122.
121.OTA 1993, p. 13.
122. It should be noted that plutonium-239 decays into another radioactive material, uranium-235. However, uranium-235 is about 30,000 times less radioactive per unit of weight than plutonium-239, and the radioactivity per canister would be correspondingly smaller. Uranium-235, like plutonium-239, is a weapons-usable fissile material. therefore, even the decay of plutonium will not end the security threat. The weight of the uranium-235 would be only about 2 percent less than the initial weight of plutonium.
123. For an analysis of the U.S. radioactive waste disposal program, see: Arjun Makhijani and Scott Saleska, High-level Dollars, Low-level Sense: A Critique of Present Policy for Management of Long-lived Radioactive Waste and Discussion of an Alternative Approach, Apex Press, New York, 1992.
124. K. J. Schneider et al. High-Level Radioactive Waste Management Alternatives, 4 volumes, Battelle Pacific Northwest Laboratories, Richland, WA 1974, Vol. 4, Section 9.
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