Disposing of the fissile materials from dismantled nuclear weapons is one of the most vexing problems the United States faces today. The Department of Energy is dismantling about 1,500 warheads per year at its Pantex facility and is currently evaluating disposition methods for the tens of tons of plutonium and highly enriched uranium (HEU) that will become surplus. These materials were produced during the Cold War, but no contingency plan was developed for a time when the U.S. would no longer want or need them. Now we face the challenge of preventing their re-use in nuclear weapons and isolating them from the environment.

IEER recently released a report on fissile materials disposition, entitled Fissile Materials in a Glass, Darkly. The report provides an independent analysis of the disposition problem and proposes some concrete solutions. It is the first study of this issue to detail a concrete plan that could put all excess plutonium into non-weapons-usable form in about ten years.

The report recognizes that all disposition methods have drawbacks. No existing technology can completely eliminate fissile materials, and the U.S. must choose from a menu of difficult disposition options. After a careful assessment, the report concludes that the most promising method for plutonium disposition is vitrification, that is, mixing plutonium with molten glass to form glass logs. Vitrification accords with U.S. non-proliferation goals (see below) and is technically feasible. The report suggests that the Department of Energy (DOE) build three or four pilot vitrification plants within the next two years to test various vitrification methods.

Fissile Materials in a Glass, Darkly considers the problems posed by both commercial and military plutonium because both can be used to make nuclear weapons. Commercial plutonium is made in commercial nuclear power plants and can be separated from spent fuel for use as a reactor fuel. This chemical-separation process is known as "reprocessing." Five countries (Britain, France, India, Japan, and Russia) continue to reprocess spent nuclear fuel. The amount of separated plutonium in the commercial sector may surpass the amount from dismantled weapons over the next one or two decades. It thus makes little sense for the U.S. to focus only on disposing of weapons plutonium without addressing the growing global problem of commercial plutonium production in these five countries. Moreover, the United States is well positioned to persuade others to stop reporecessing because it has itself stopped both military and civilian reprocessing. The recommendations of the report are designed to achieve the goal of a universal, interim halt to reprocessing.

There is no guarantee of completely safe storage of plutonium in any country, but fissile materials in Russia pose especially large security risks at present. Russia is not only reprocessing spent fuel (about 30 metric tons of plutonium are stockpiled at one reprocessing site), but it is also dismantling over 1,000 warheads per year. Russia is unlikely to put its plutonium into a non-weapons-usable form until the U.S. does. Indeed, there is every sign that Russia is determined to press ahead with separating even more plutonium. Given the political and economic instability there, it is important for the U.S. to select and implement a disposition method quickly and persuade Russia to do the same.

Fissile Materials in a Glass, Darkly has five principal recommendations:

1. The U.S. should declare excess plutonium a liability.
This step is essential for the U.S. government to strengthen its hand in dissuading other countries from separating plutonium. The liabilities of plutonium are widely acknowledged (see Science for Democratic Action Vol. 3, No. 3, and Plutonium: Deadly Gold of the Nuclear Age. These can be ordered from IEER.). The U.S. has stopped production of plutonium for weapons and wisely abandoned the commercial use of plutonium over a decade ago. Recently, Secretary of Energy Hazel O'Leary stated that plutonium is a global security risk and an economic liability. Formalizing these practices and statements into a strong policy declaration on the security, economic, and environmental liabilities of plutonium, preferably by President Clinton himself, will give the U.S. the solid footing it needs to convince other countries to cease reprocessing. In October of 1994, IEER was joined by thirty-eight U.S. organizations and seven individuals in sending a letter to President Clinton urging him to make such a declaration.

2. Vitrify excess plutonium: no reactor technologies should be used.
In January of 1994, the National Academy of Sciences released a report on fissile material disposition. The report stated that the two most promising methods for disposing of plutonium are either vitrification or conversion into mixed-oxide fuel (MOX) for use as fuel in existing nuclear reactors.

Fissile Materials in a Glass, Darkly recommends vitrification over the MOX option for several reasons. First, vitrification accords with U.S. non-proliferation goals. It would send a signal to the five countries that reprocess that the U.S. considers plutonium a waste and will not use plutonium for energy purposes even when the plutonium is "free." The MOX option, in contrast, would legitimize the use of plutonium as a nuclear fuel and would undermine U.S. efforts to dissuade Britain, France, India, Japan, and Russia from continuing to separate more plutonium.

Second, the MOX option could also lead the U.S. down the dangerous path toward a plutonium energy economy by creating vested interests in plutonium use. Once the money is invested to build a plant to convert weapons plutonium into MOX fuel, and once nuclear reactors are re-licensed to burn MOX fuel, there will be a strong institutional momentum to continue to use plutonium as a nuclear fuel even after all the weapons plutonium has been run through reactors.

Although the electricity generated from using the plutonium in reactors does offset some of the costs of the MOX option, fabricating the MOX fuel would be so expensive (because of worker protection and safeguards needs) that the National Academy of Sciences estimated that the overall costs of the MOX option and vitrification would be about the same.

While vitrification offers several advantages, it also has some drawbacks. Although there is extensive knowledge and experience in other countries regarding MOX fabrication and use, large-scale vitrification of plutonium has not been tried before. Nevertheless, vitrification marries two well-known technologies, glass-making and plutonium metallurgy, and the report concludes that there are only a few technical hurdles that need to be overcome. Further, France has been vitrifying its high-level wastes for over two decades, and the U.S. could draw on the French experience when designing plutonium vitrification plants.

3. Build three or four pilot vitrification plants.
After examining the troubled history of U.S. high-level waste vitrification efforts, the report concludes that the problem is not that vitrification is too difficult, but that it was not properly carried out. The Department of Energy built a one billion dollar full-scale vitrification plant (the Defense Waste Processing Plant at Savannah River Site) without ever having cast a full-size glass log with real radioactive waste. IEER thus recommends building three or four pilot vitrification plants so that the technical, environmental, and safety issues surrounding vitrification of plutonium can be studied and worked out.

More than one pilot plant is needed because several different methods for vitrifying plutonium are promising. Most studies recommend that the plutonium be vitrified along with high-level radioactive waste so that the resulting glass logs would be highly radioactive, creating a strong barrier to attempts to re-extract the plutonium. The glass logs would meet the "spent-fuel standard" recommended by the National Academy of Sciences. That is, it would be as hard to extract plutonium from the glass logs as it would be to produce new plutonium by reprocessing spent fuel.

This method of vitrification has some disadvantages, however. It take a long time to complete because expensive shielding and safety measures would be needed to handle the high-level waste. Moreover, the radioactive wastes will largely decay after 500 years while the plutonium will remain a threat to security, health, and the environment for over 100,000 years. Finally, with such a high barrier to re-extraction, it would be very difficult to convince countries to stop reprocessing and to vitrify their plutonium with the potential for re-extraction (see recommendation number 4 below).

The IEER report argues that it may be better to use a slightly lower barrier to re-extraction of the plutonium to complete the vitrification process sooner and to aid the goal of achieving a universal, interim halt to reprocessing. For example, depleted uranium or a rare-earth metal such as europium could be added to the plutonium before vitrification. It would still be very difficult to chemically separate the plutonium from these materials, but expensive radiation shielding would not be needed during vitrification.

One method of vitrification that holds particular promise is to vitrify the plutonium without high-level radioactive wastes, and then to add a gamma-emitting fission product such as cesium-137 to the canister that will hold the glass log. This would provide a high barrier to theft and re-extraction of plutonium by making the container highly radioactive, but fewer fission products would be needed than if they were added to the glass itself. As a result, worker exposures to radiation and environmental risks may be reduced.

Clearly, further study, laboratory work, and pilot plant operation will be needed to evaluate and compare the various vitrification methods outlined above. Constructing pilot vitrification plants would give the Department of Energy the real-world experience it needs in order to build sound facilities for plutonium vitrification.

4. Create an international financial guarantee for the re-extraction of plutonium from glass.
This recommendation is the key to achieving a global, interim halt to commercial plutonium production. The countries that are currently reprocessing generally recognize that plutonium is an uneconomical fuel in the near term, even if they do not say so publicly.

Their rationale for reprocessing, then, is that plutonium and the technology to produce it may be needed in the long term if uranium, which is the most common nuclear fuel, becomes scarce. This would be like producing oil from oil shale rock today at $70 a barrel -- more than three times the current market price -- on the assumption that the price of oil will increase to at least $70 a barrel in the coming decades.

In the meantime, commercial plutonium is piling up in large quantities, posing a large proliferation risk, especially in Russia. Britain, France, India, Japan, and Russia may be more easily convinced to stop reprocessing and to vitrify their current stocks of plutonium (thus making it non-weapons-usable) if an international financial guarantee were given for re-extraction of the plutonium from the glass if plutonium ever became an economical fuel. The vitrified plutonium would in effect become a plutonium reserve, which would alleviate countries' fears about uranium scarcity and energy self-sufficiency. Of course, the details of such a financial guarantee still need to be worked out. For example, international monitoring would be required to ensure that the plutonium is not used for nuclear weapons and is removed from the reserve only with international consensus that plutonium has actually become economical.

5. Create a reserve of uranium reactor fuel.
As another incentive to halt reprocessing, a reserve of low-enriched uranium fuel (LEU) suitable for nuclear reactors should be created. This would provide an alternative to plutonium-based fuels for decades, and like the financial guarantee discussed above, it would alleviate countries' concerns about uranium scarcity and energy self-sufficiency. The uranium reserve could be formed by diluting weapons grade uranium to make LEU, which is suitable for use in reactors but cannot be used to make weapons without re-enrichment to HEU. Any LEU that remains after the reserve is created could be released to the uranium market.

The report urges a full programmatic environmental impact statement (PEIS) of this issue to be done as part of a PEIS on weapons usable fissile materials.

Implementing the five principal recommendations of the report would reduce to a large extent the dangers posed by fissile materials around the globe, but the long-term future of this problem is inextricably tied to the future of nuclear energy, since essentially all nuclear reactors produce plutonium in their spent fuel.

The report is skeptical that DOE can carry out the needed program without institutional change and openness. While there have been some very positive changes within the Department of Energy, especially in its openness initiatives and its opposition to funding the Advanced Liquid Metal Reactor (ALMR), it is not clear that these changes have permeated the entire nuclear-weapons complex, nor is it clear that the positive changes will continue. It is not even clear that the agency whose main mission it was to build bombs is well-suited for dismantling them and disposing of their materials. Continued public interest in the disposition issue, combined with the DOE's willingness to address public concerns, are vital to ensure that vitrification is chosen as the disposition option and that it is carried out with the necessary diligence to protect the environment and the health and safety of workers and surrounding communities.

Institute for Energy and Environmental Research

Comments to Outreach Coordinator: ieer@ieer.org
Takoma Park, Maryland, USA

Last updated: August, 1996