[NCI Logo]



Bulletin of the Atomic Scientists, March/April 1997

MOX is too expensive and too risky--and pursuing it sends the wrong message about recycling plutonium.

Proponents of the Clinton administration's "two-track" policy on weapons-plutonium disposal insist it is essential to pursue both tracks in the United States and in Russia. They claim that those who oppose the use of mixed-oxide (MOX) fuel in a plutonium disposal plan "are relying on simple ideological positions."1

But the case for a one-track policy, which treats plutonium as waste and focuses exclusively on immobilization, cannot be so neatly dismissed. The one-track approach is both practical and symbolically valuable. A U.S. decision to concentrate limited resources on validating immobilization would help, not hinder, the pace and scope of the disposal effort.

As the discussion of plutonium disposal evolves from sweeping generalities to devilish details, it will become apparent that an approach depending heavily on MOX burning cannot be effectively implemented at the required scale in a reasonable time frame. It will also become clear that the MOX option is fraught with a variety of risks that are less severe or absent in a program of immobilization.


A substantial fraction of the excess weapons plutonium in the United States (and no doubt in Russia as well) is in the form of scraps and residues that would require extensive chemical purification before they could be incorporated into MOX fuel. Because reprocessing these materials would be expensive and have proliferation implications, the Energy Department has made a commitment to immobilize at least eight metric tons of excess plutonium in impure forms. Immobilization will therefore be part of the U.S. program whether or not MOX is employed. And since immobilization can handle purer forms of plutonium as well (such as oxides produced from weapon pits), why consider MOX at all?

The answer from two-track proponents is that unless the United States spends additional hundreds of millions (but probably billions) of dollars on a duplicative effort to develop both MOX and immobilization, Russia will refuse to consider immobilization—and it may even refrain from disposing of plutonium. Thus, it is the two-trackers who are driven by ideology, insisting that the United States must shape its disposal policy to indulge Russia's ideological commitment to the use of military plutonium in reactors no matter what the expense or risk.

Deployment of both tracks in both countries is a main recommendation of a group of scientists from the U.S. and Russian academies of science—known as the ''Holdlen-Velikhov Commission" (also called the "Bilateral Commission"). The group's September 1996 report, promoted by its authors as a significant breakthrough, actually embodies a surrender to Russia's terms.

Although the report says that "each country will decide for itself how its excess plutonium will finally be divided between the two . . . methods," its pro-MOX tilt is manifest in the supreme importance the group places on "financing and constructing adequate capacity for processing pits to oxide and for fabricating . . . MOX fuel."2 There is no mention of the need to finance immobilization. Moreover, the report makes clear that it does not regard immobilization as appropriate for pits, only for plutonium in forms less easily converted to MOX.

The commission's conclusion directly contradicts a U.S.-Russian government report released at around the same time, the Joint United States/Russian Plutonium Disposition Study. The Joint Study concluded that "the United States and Russia need not use the same plutonium disposition technology. Indeed . . . it is likely that the best approaches will be different in the two countries."

Reducing stocks slowly ...

Nonetheless, two-track proponents have presented several arguments to support their contention that it is essential that the United States employ the MOX option. These arguments are misguided and misleading.

First, they argue that "both options face technical and institutional obstacles that will need to be overcome," and therefore both need to be developed in case one should encounter excessive delay. However the Energy Department's own data reveal that even under the most optimistic scenario for MOX disposal, immobilization could begin sooner, complete the job more rapidly, and require fewer facilities to manage and safeguard.3

Moreover, the technical and environmental risks associated with immobilization, a straightforward industrial process, are far smaller than those associated with the plan to load aging U.S. commercial reactors with full cores of weapons-grade MOX fuel, a practice with no precedent. MOX proponents exaggerate the significance of safety issues associated with immobilization, Such as the remote r isk of future criticality in a geologic repository, while taking little notice of the numerous unresolved safety issues associated with the substitution of MOX for uranium fuel, such as an increase in reactor instability in the event of an accident causng a sudden cooling of the core.

Although dual-track proponents fear that reliance on immobilization alone could lead to delay, it is the MOX route that should give them cause for concern. Preliminary studies indicate that the existing Russian VVER-1000 power reactors will require modifications, ineluding installation of additional control rods and the use of expensive enriched boron in the coolant, even if only a third of their cores are loaded with MOX. These studies also raise the possibility that VVER-1000 reactors will be unable to use full MOX cores under any circumstances. Given these constraints, using MOX to dispose of Russian plutonium at a modest rate of three metric tons a year would be a formidable endeavor requiring all seven of Russia's VVER-1000s and another five in some other country, perhaps Ukraine.4 In contrast, immobilization could easily achieve a greater disposition rate with two facilities at a single site.

Establishing an effective Russian MOX disposition program would require many expensive facilities and raise troubling security issues. An approach that involves the fabrication of weapons-grade MOX fuel, a process that is more eomplex and therefore intrinsically more difficult to safeguard than immobilization, as well as distribution of the fuel to numerous sites inside and outside Russia, will result in a vast enlargement of the safeguards and security burden, and is hardly a satisfactory solution.5 There has been no realistic discussion of the cost and effort that would be required to commandeer a large fraction of the Russian nuclear power sector for this mission or to keep it on track through completion. Russia's nuclear power industry suffers from ballooning debt, and nuclear workers have not been paid in months. If the United States ultimately commits itself to underwriting the operation of Russian nuclear power reactors for plutonium disposition, it may end up in a black hole, shouldering much of the cost of keeping a fleet of aging reactors of dubious safety running for several decades.

... or not at all?

Beyond the environmental and financial benefits of forgoing the MOX option, there are substantial nonproliferation benefits as well. The United States is regarded internationally as the leading opponent of elosed nuclear fuel cycles and plutonium use, and its authority in this respect will suffer if it chooses to fund and develop a large-seale MOX infrastructure. It is naive to assert that the negative "fuel cycle policy signal" associated with burning MOX will be counteracted if high-level officials simply say that it does not represent a policy shift. An intensive European lobbying effort for MOX disposal generally, and a recent French statement declaring that U.S. support for a Russian MOX plant 'would definitely be a symbolic success for France," are clear indications of the financial and strategic importance of MOX disposal to the international plutonium industry.6 Dual-track supporters argue that because immobilized plutonium remains weapons-grade, it would be "somewhat easier" to recover it and reincorporate it into weapons than it would be to reuse plutonium from spent MOX fuel. They insist that reactor-grade plutonium could not be introduced reliably into the current arsenal without redesigning weapons and conducting now-forbidden nuclear tests. They also claim that if the United States immobilizes its warhead plutonium, Russia and the rest of the world will suspect that it is not foreclosing the possibility of reusing it for military purposes.

This argument, which originated in a report by the pro-MOX American Nuclear Society, is without merit.7 It is well understood in the technical community that both the United States and Russia have weapons designs that are "predetonation-proof"—that is, resistant to the intense neutron backgrounds of a nuclear battlefield. As a consequence, they are impervious to the buildup of neutron-emitting plutonium 240 in reactor-grade plutonium. Therefore, reactor-grade plutonium can be used in modern warhead designs with minimal modification. Two-track proponents do a disservice to the cause of disarmament by perpetuating the myth that reaetor-grade plutonium is decisively less useful than weapons-grade to advanced nuclear states.

The argument is also a smoke-screen used to conceal much more serious problems with the MOX option. The most important factor bearing on reuse of either spent MOX fuel or immobilized plutonium is not the isotopic composition of the plutonium, but the radiation barrier provided by the waste forms. In either case, plutonium recovery requires the use of a remotely operated, heavily shielded reprocessing plant. Therefore, verifying the shutdown of reprocessing plants in both countries would be the most significant barrier to rapid rearmament.

Instead, Russia intends to continue reprocessing plutonium indefinitely, as it now does in unsafeguarded plants. (The United States also continues to reprocess a backlog of military spent fuel, ostensibly for health and safety reasons, with relatively little plutonium being recovered.)

It borders on the absurd to proceed with plutonium disposal as long as new separated plutonium eontinues to be produced. But the Holdren-Velikhov Commission did not oppose Russia's plan to continue extracting plutonium from spent uranium fuel—nor did it rule out the eventual reprocessing of the warhead-derived MOX fuel. This may not be surprising—Russian nuclear scientists defend reprocessing as vehemently as they oppose immobilization. But Russia will have even less incentive than it does now to stop producing plutonium if the West provides billions of dollars for a new plutonium recycling infrastructure.

Thus, the approach advocated by the two-trackers—granting Russia virtually every concession where plutonium is concerned—seems likely to defeat the goal of reducing separated plutonium stockpiles.

Another argument used by two-trackers is that if the United States were not to pursue the MOX option at home, it would sacrifice "whatever leverage [it] may have" on the Russian MOX program. This simply doesn't make sense. The U.S.-Russian nuclear disarmament process is fundamentally bilateral in character, and the United States will always have substantial influence in the areas of safeguards, security and verification, whatever the means of disposal.

Moreover, the United States possesses the ultimate tool for exerting leverage over the Russian program—money. There is little question that ultimately the United States will bear most of the financial burden of Russian disposition activities.

European nations have aggressively promoted the MOX option, but their enthusiasm dwindles when the issue of financing comes up. At the Paris meeting of the P-8 (the Group of Seven plus Russia) last October, France and Germany magnanimously offered to build a pilot-scale MOX plant in Russia, but not to finance it. They offered to contribute only seven percent of the $300 million cost.8

The United States, on the other hand, is voluntarily abandoning its prerogatives by displaying extreme timidity in dealing with Russia on plutonium issues. This was apparent at the Paris meeting, when the United States was rebuffed on two conditions it maintained were critical regarding the Russian MOX program—first, that a MOX plant be used only for weapons plutonium (so that the plant's existence would not be used to justify the continued reprocessing of civil fuel), and second, that no spent MOX fuel would be reprocessed until after Russia had disposed of a mutually agreed quantity of weapons plutonium.9 In addition, the design of Russia's proposed pilot MOX fuel plant includes a production line for fast-breeder reactor fuel, a feature contrary to long-standing U.S. anti-breeder policy.

First things first

If the United States aequiesces in Russia's desire to pursue MOX, it could lose the leverage it already has. Since the MOX technology that Russia and the United States would acquire is of European origin, U.S. participation in fundamental technology and design issues would automatically be marginalized. The better approach for the United States is to promptly demonstrate an immobilization technology that it can offer Russia when the European MOX proposal falls of its own economic weight.

This approach is dismissed by two-trackers as unrealistic, but the fact remains that the United States has never made a serious attempt to make immobilization financially attractive to Russia. Russia's top nuclear official at one point put a price tag of $2.4 billion on 100 metric tons of plutonium—not an astronomical sum in U.S. national security terms for inducing Russia to directly dispose of its surplus plutonium without the use of MOX fuel.10 In the meantime, the United States and Russia should take the all-important first step toward plutonium disposal of converting weapon pits into an intermediate, unclassified oxide form. They should work cooperatively to develop a mutually acceptable and verifiable technology for pit conversion, and to insure secure storage of the converted material. Conversion to oxide will be required for both the MOX and immobilization approaches, although different processes may be necessary for each route. (A dry conversion process would be adequate to produce feed for immobilization, but to produce feed meeting the strict specifications for MOX fabrication may require a more expensive and less secure aqueous process.)

If the Russians are determined to pursue the dangerous MOX disposition path because of economic ignorance, misguided infrastructural interests, and insensitivity to environmental and nonproliferation concerns, let them. But it is unreasonable to expect Americans to pay for it, and foolish to demand that Americans follow the same course just to avoid shattering Russian delusions about the value of plutonium.

Edwin S. Lyman is the scientific director of the Nuclear Control Institute in Washington D. C.; Paul Leventhal is its president.


1. John P. Holdren and John Ahearne, "A Clear and Present Danger," Washington Post, Dec. 18, 1996, p. A23.Back to document

2. John P. Holdren, et al, "Interim Report of the U.S.-Russian Independent Scientific Commission on Disposition of Exeess Weapons Plutonium" (unpublished), Sept. 16 1996, p. 2.Back to document

3. Office of Fissile Materials Disposition, U.S. Energy Department, Technical Summary Report for Surplus Weapons-Usable Plutonium Disposition, Rev. 1, Oct. 31, 1996, Table ES-2, p. ES-ll. According to this report, immobilization would begin as much as six years sooner and might be completed 13 years before a MOX program that used five light-water reactors.Back to document

4. Ann MacLachlan, "AIDA/MOX Study Concludes with Choice of Major Process Options," NuclearFuel, Dec. 2, 1996, p. 6.Back to document

5. U.S. Energy Department, "Final Non-Proliferation and Arms Control Assessment of Weapons-Usable Fissile Matelials Storage and Excess Plutonium Disposition Alternatives," January 1997, pp. 111, 119; National Academy of Sciences Committee on International Security and Arms Control, Manageement and Disposition of Excess Weapons Plutonium: Reactor Related Options (Washington, D.C.: National Academy Press, 1995), p. 243.Back to document

6. Nuclear Notes from France (French Embassy, Washington, D.C.) No. 43, Oct.-Nov. 1996.Back to document

7. American Nuclear Society Special Panel Report, "Protection and Management of Plutonium," American Nuclear Society (La Grange Park, Illinois), Aug. 1995, p. 10.Back to document

8. Ann MacLachlan, "Paris Meeting on Military Pu Disposition Says No Option Should be Totally Ruled Out," NuclearFuel, Nov. 4, 1996, p. 1.Back to document

9. Ann MacLachlan, "Consensus Building for Russia to Burn Pu in Reactors as U.S. Softens Stand," NuclearFuel, Dec. 2, 1996, p. 12.Back to document

10. Victor Mikhailov et al., Plutonium in the Power industry, paper presented to the Sixth International Workshop on the CTB and Nuclear Warhead Elimination, co-sponsored by the Natural Resources Defense Council, the Federation of American Scientists, and the Moscow Physical-Technical Institute, December 15-17, Washington, D.C. 1993, p.9.Back to document

[Pu Disposition Page] Pu Disposition Page[What's New] What's New Page[Home Page]Home Page