Research Brief

Since 1991, the world has worried that fissile materials from dismantled nuclear warheads will fall into the wrong hands. Although fears that military leftovers might be diverted and refashioned into nuclear weapons are well justified, little attention has been focused on a possibly more serious threat: the spread of weapon-usable plutonium separated from the spent fuel of civilian nuclear reactors. In Limiting the Spread of Weapon-Usable Fissile Materials, authors Brian G. Chow and Kenneth A. Solomon take an expansive view of the proliferation threat. They recommend a bold course of action for controlling the flow of weapon-usable fissile materials[1] from both civilian and military sources. It involves

  • the world's undertaking a four-point plan to make civilian nuclear power more proliferation-resistant
  • the United States and its wealthier allies' buying up and removing weapon-grade plutonium and blended-down uranium from the former Soviet republics.

The Scope of the Problem

Chow and Solomon estimate that by the year 2003, 200 metric tons of weapon-grade plutonium and another 330 metric tons of reactor-grade plutonium will be recovered from spent fuel. This means that there will be enough weapon-grade plutonium from dismantled nuclear weapons to make 40,000 primitive bombs and enough reactor-grade plutonium from spent fuel to make another 47,000 bombs (see figure). By 2003, 1,000 metric tons of highly enriched uranium will be recovered from dismantled weapons—enough to make 65,000 bombs.

Number of primitive nuclear bombs that can be made from separated plutonium

In addition to the rapid accumulation of weapon-usable materials, the presence of sensitive nuclear facilities[2] throughout the world is a problem. Such facilities are a threat because they can produce weapon-usable materials. Any country that can obtain 15 kilograms of highly enriched uranium, 5 kilograms of weapon-grade plutonium, or 7 kilograms of reactor-grade plutonium from a sensitive nuclear facility can build a bomb in a few days or weeks. No safeguard scheme, including that of the International Atomic Energy Agency, can protect the world if such sensitive materials and facilities are widely available.

Making Nuclear Power More Proliferation-Resistant

To build a more proliferation-resistant future for civilian nuclear power worldwide would require that the use of plutonium as fuel be postponed indefinitely because it creates no economic benefits but much proliferation risk. More specifically, the following four-point plan should be enacted:

  • Terminate or drastically reduce both military and civilian plutonium activities worldwide.
  • Prolong the world's reliance on existing nuclear reactors that operate in the once-through mode. Doing so entails improving reactor efficiency and identifying additional uranium resources.
  • Encourage the development of advanced nuclear reactors[3] that will be even more efficient and proliferation-resistant than current reactors.
  • Confine, to the extent possible, sensitive nuclear materials and facilities within the five declared nuclear weapon states while agreeing to share the benefits of sensitive nuclear activities, if any, with non-nuclear weapon states.

This four-point program will enable countries to use nuclear energy peacefully, well into the future, with far less risk of nuclear proliferation.

We'll Buy It!

Economic hardship and political instability in the former Soviet republics make especially high the risk that their weapon-usable materials will be diverted to despotic national or subnational groups, or will be refashioned into bombs if Russia or other republics revert to tyranny. Buying and removing weapon-usable materials from the former Soviet republics eliminate this danger.

The United States has already committed $12 billion to purchasing blended-down uranium from Russia.[4] Blending highly enriched uranium with natural or depleted uranium produces low-enriched uranium—an economical reactor fuel that is not suitable for weapons. The United States made this commitment to buy, expecting to recover the full amount through resale to domestic and foreign utilities.

However, Chow and Solomon predict that the United States will lose money on the transaction. Furthermore, $12 billion is not enough to buy and remove all the surplus highly enriched uranium from the former Soviet republics. Additional purchases will be required. The United States should encourage France, Germany, Japan, the United Kingdom, and others to repurchase blended-down uranium from the United States or to buy such uranium directly from the former Soviet republics. In this manner, U.S. allies can share the financial burden of the transaction and participate in reducing nuclear danger.

Because weapon-grade plutonium is difficult to render unusable for weapons, it poses a hazard if it remains in Russia and the political situation there takes a turn for the worse. And because weapon-grade plutonium is uneconomical to use in commercial nuclear power plants and is costly to store, it has very little value for Russia. Therefore, the United States, alone or with help from France and the United Kingdom, should encourage Russia to sell its surplus weapon-grade plutonium by offering $1 billion. Then the United States can remove the plutonium from Russia for safekeeping or disposal.


  • [1] Weapon-usable fissile materials are defined as uranium with a fissile isotopic content of 20 percent or more and plutonium of any isotopic composition. Weapon-usable plutonium includes plutonium separated from the spent fuel of commercial reactors (reactor-grade plutonium) and plutonium recovered from dismantled nuclear weapons (weapon-grade plutonium). Plutonium that is still embedded in the intensely radioactive spent fuel of commercial reactors is not considered weapon-usable.
  • [2] Sensitive nuclear facilities can produce, separate, or handle weapon-usable fissile materials. They include plutonium-reprocessing and -fabrication plants, plutonium-fueled reactors, and some uranium-enrichment plants. A typical commercial reactor is not a sensitive nuclear facility because it does not use weapon-usable materials in its fuel and its produced plutonium is still embedded in intensely radioactive spent fuel. It operates in the once-through mode, meaning that the plutonium and uranium in the spent fuel are not reused.
  • [3] These advanced reactors do not have to be breeders; highly efficient converters will do. Both uranium- and thorium-based cycles should be considered.
  • [4] Russia is expected to share the proceeds of this sale with Ukraine, Kazakhstan, and Belarus, which have agreed to turn nuclear warheads stationed in their territories over to Russia.

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