Plutonium is a Liability A Commentary on a National Academy of Sciences Study* by Arjun Makhijani The National Academy of sciences (NAS) issued an historic report in January 1994, entitled Management and Disposition of Excess Weapons Plutonium.** Under the direction of the NAS Committee on International Security and Arms Control (CISAC), the report examines the problem of the management and disposition (long-term management) of plutonium from unwanted nuclear weapons at the end of the Cold War. The report warns that excess military plutonium poses high security risks and at the same time affords no economic advantage for the foreseeable future. It states that "exploiting the energy value of plutonium should not be a central criterion for decision-making, both because the cost of fabricating and safeguarding plutonium fuels makes them currently uncompetitive with cheap and widely available low-enriched uranium fuels, and because whatever economic value this plutonium might represent now or in the future is small by comparison to the security stakes." The NAS analysis shows that even when the plutonium itself is assumed to be "free," it costs more as an energy source than uranium because plutonium processing and fabrication of fuel containing plutonium is so expensive. (In most cases, plutonium is used in a reactor fuel known as MOX -- a mixture of oxides of plutonium and uranium). The report also discusses the issue of "civilian plutonium," or plutonium recovered from reprocessing spent fuel from civilian power plants. Recognizing the security risks from all separated plutonium, including that in civilian nuclear power programs, it recommends that the US and Russia "pursue a reciprocal regime of secure, internationally monitored storage of fissile material, with the aim of ensuring that the inventory in storage can be withdrawn only for non-weapons purposes." As Russia continues to experience severe economic problems and political uncertainty, this is a crucial and very urgent recommendation. The report also implies that civilian plutonium is a liability, comparing it with producing oil from oil shale rock, which will remain uneconomic for decades. Moreover, oil from shale poses no comparable security risk. In taking on the subject of civilian plutonium, albeit gingerly, the NAS report has contributed to progress on resolving plutonium disposition issues across the board. Recommendations The NAS report recommended the possible use of MOX as one long-term plutonium disposition option. If MOX were used in existing nuclear reactors, the plutonium remaining in the waste would be sufficiently mixed with radioactive fission products that it could not be used in weapons without costly and dangerous processing. Alternatively, the report suggested mixing excess plutonium with radioactive wastes and molten glass -- a process known as vitrification. Both of these options would make it difficult, costly, and dangerous to re-extract the plutonium for use in weapons. The criterion by which these options were adjudged suitable was the "spent fuel standard" -- that is, it should be at least as difficult to use it to make nuclear weapons from the end product as it would be to make weapons from unreprocessed spent fuel from civilian nuclear power plants. The report also recommended considering deep boreholes (two to four kilometers deep) for evaluation as a disposal option, but recognized that retrievability from such boreholes could pose problems because, in that case, the plutonium could be re-used to make nuclear warheads. On the other hand, the report notes that retrievability might be an advantage in negotiations with the Russian government, which views plutonium as an economic resource. But plutonium would continue to pose a threat even in these hard-to-handle radioactive forms. The report notes that most fission products, which make spent fuel or radioactive glass logs difficult and expensive to handle, decay well before plutonium does. It therefore recommended research into a variety of transmutation options using critical and sub-critical reactors that, in the very long-term, could fission essentially all existing plutonium. The NAS panel recommended this approach as a supplement to, and not a substitute for, the two main options. None of these disposal options can be accomplished quickly -- it will be well into the next century before they are completed. As Wolfgang Panofsky, Chair of the NAS plutonium panel, told the Washington Post, "the world is condemned to having to baby-sit this material for at least another decade," (January 25, 1994). As part of that atomic baby-sitting exercise, the NAS report recommends, all inventories of fissile materials must be declared, and put into internationally or bilateral verified storage. Another Option One possibility for relatively quick processing of plutonium (within the next decade) is to vitrify it alone, without mixing it with radioactive waste. Because plutonium emits mainly alpha radiation, which is dangerous only when inside the body, it can be vitrified without massive shielding, unlike the far more complex plant that would be needed if radioactive wastes are mixed in. The NAS report considered such an option, but did not recommend it, since the plutonium could be recovered after processing at far lower levels of effort than with spent fuel from reactors, a disadvantage from the point of view of potential re-use in weapons. However, the report does note that "experience with separating materials from glass is far less widely disseminated than experience with spent fuel reprocessing." For this reason, IEER advocates vitrification of plutonium alone, provided the technical aspects are properly worked out in a pilot plant. This measure would provide a considerable barrier to re-use. Moreover, as with deep boreholes, a potential for re-extraction could be an advantage in the near future arriving at an agreement on disposition with Russia. Finally, the glass could be re-melted and mixed with radioactive waste at a future date. Given the collapse of the economy in the former Soviet Union and the accompanying political and military instability, time is the most important factor in coping with excess plutonium. Added to the problem is the Russian government's attachment to plutonium as a resource. The NAS report should have put the vitrification of plutonium alone at least on a par with disposal in deep boreholes. We recommend that DOE build a pilot plant to test the process with plutonium metal and with various chemical residues present in the DOE complex (see the article on Plutonium Vulnerabilities). This would provide much of the environmental, health, and safety data needed for a sound decision on the vitrification of plutonium. Finally, the NAS report does not mention the use of photons as a possible transmutation option. This may be worthy of some theoretical consideration at this stage along with other long-term possibilities, though the engineering challenges will probably be great. Photons in a narrow spectrum (about 10 to 15 MeV for plutonium-239), called the "giant resonance region," can induce fission with a high probability relative to other parts of the electromagnetic spectrum. Such photons can be generated using electron accelerators. No Nuclear Nirvana Its makers had hoped that plutonium would lead the world to a nirvana created by a boundless source of energy. Glen Seaborg, who led the team that first isolated it, felt that plutonium would provide the energy to make deserts bloom and enable "planetary engineering"; there would be earth to moon shuttles; sea water would be made potable. "My only fear is that I may be underestimating the possibilities," he said in 1968. These were fond hopes, not engineering conclusions. The high cost of deriving energy from plutonium has to do with the enormous precautions that must be taken in processing it (is highly carcinogenic), with the large capital investment needed for building nuclear reactors, and the difficulty and expense of decommissioning reactors and disposing of their radioactive wastes. Other burdens stem from safeguarding it, since all grades of plutonium are usable for making nuclear weapons, another important fact that the NAS report highlights. Plutonium was regarded in most of the post-World-War-II era as the gold of a glorious nuclear age to come. It was not to be. Rather, it has become a terrible liability. Today, knowledge of nuclear weapons technology is so widespread that getting access to it is not a substantial barrier to proliferation. Rather, as the NAS report notes, "access to fissile material is the principal technical barrier to proliferation in today's world...." That is why complete elimination of nuclear-weapons-usable materials is a necessary condition for achieving both nuclear non-proliferation and nuclear disarmament goals.