The plutonium challenge for the future

In this paper author deal with the weapons-usable plutonium and with the possibilities of their managing. Russia has not disclosed the amount of plutonium produced, but various estimates indicate that the production was about 130 tonnes. Production has been curtailed in Russia; three dual-purpose reactors still produce weapons-grade plutonium - two at Tomsk-7 (renamed Seversk) and one at Krasnoyarsk-26 (renamed Zheleznogorsk Mining and Chemical Combine). In a 1994 United States-Russian agreement that has yet to enter into force, Russia agreed to close the remaining operating reactors by the year 2000. Treaties between the United States and Russia have already cut the number of nuclear warheads from more than 10,000 to about 6,000 under START 1, which has been ratified, and to about 3,500 under START 2, which still awaits approval. If Russia and the United States conclude START 3, that number could drop to between 2,000 and 2,500. On September 2, 1998, the Presidents of the United States and Russia signed the 'Joint statement of principles for Management and Disposition of Plutonium, Designated as No Longer Required for Defense Purposes.' In this joint statement the Presidents affirm the intention of each country to remove by stages approximately 50 metric tons of plutonium and to convert the nuclear weapons programs, and to convert this material so that it can never be used in nuclear weapons. These 100 tonne of plutonium must be managed in proper way such that it becomes neither a proliferation for an environmental risk. The United States has proposed that it manage it's 50 tonnes by a dual approach-once through MOX burning of a portion of the plutonium and immobilization in a ceramic matrix followed by en- casement in high level waste glass. Russia has proposed that it manage its full 50 tonnes by burning in a reactor. The MOX program in the United States would bum the cleaner plutonium metal and residues. Weapons components would be converted to plutonium oxide, followed by dissolution utilizing an Ag(II)-nitric acid method. The plutonium would be purified by one cycle of solvent extraction, precipitated as plutonium oxalate and then converted to oxide. This would not only remove the gallium but would provide the correct morphology for preparation of the MOX fuel. The Immobilization program in the United States would mineralize the plutonium contained in a variety of residues that were left in place when the weapons production complex was shut-down at the end of the cold war. These residues have a wide range of impurity contents, typically from a few parts per million to > 90 wt. %. Plutonium in these residues would be blended to level the impurities and thereby avoid reprocessing of this plutonium. This blended plutonium would then be mineralized at high temperature in a titanate ceramic followed by canning of the ceramic pucks. These cans would by loaded into a magazine and then locked into place within a stainless steel canister. The plutonium ceramic would then be encased in high level waste glass. A high radiation field would protect the plutonium in the spent MOX fuel and the immobilized ceramic form for some period of time. Within the time period of the high radiation field, these forms would be entombed in an underground repository. This, however, disposes of only 50 tonnes of the approximately 1700 tonnes of the worldwide weapons- usable plutonium. Russia will dispose of another 50 tonnes via the MOX burning route. Worldwide approximately 1600 tonnes of weapons-usable plutonium is still available either as spent fuel or as separate plutonium oxide. Is society prepared to deal with these 1600 tonnes of plutonium? At the present growth rate, before the United States and Russia completes the disposition of the 100 tonnes of weapons-grade plutonium, the worldwide stockpile will exceed 2000 tonnes. (author)