In the twentieth century, all Russian or American nuclear warheads contained a total of about 100 tons of plutonium and 500 tons of highly enriched uranium.
In scientific and technological programs, there are relatively simple ways to effectively use highly enriched uranium by diluting and processing it to 3 to 4 percent uranium-235 and using it to make heat-releasing elements for nuclear power plants. A treaty was signed between Russia and the United States on the sale to the United States of 500 tons of Russian military uranium suitable for use in nuclear power plants.
The problem of disposing of military plutonium is more complex. At present neither the United States nor Russia has mastered an ecologically safe and economically affordable process for the effective use and elimination of plutonium. The difficulty of disposing of plutonium is compounded by the fact that plutonium is highly toxic and has a long half-life (24,000 years). 2 to 3 grams of plutonium spread over an area of 1 square kilometer can adversely affect the lives of local residents for thousands of years to come.