Since 1987, the United States and the countries of the former Soviet Union have signed disarmament treaties to reduce nuclear weapons stockpiles by about 80%. Nuclear weapons have both highly enriched uranium (HEU) of at least 90% 235U and plutonium that can be refabricated and used as nuclear fuel. HEU can be blended down with depleted uranium—the mostly 238U that is left over after enrichment for 235U—or natural uranium to make the low enriched uranium (LEU) of 3-4% that is used in nuclear reactors. There are about 2,000 tonnes of HEU in US and Russian nuclear weapons stockpiles, about 12 times the annual world mining production of uranium. Plutonium can also be blended with ura­nium to make a mixed oxide fuel (MOX) that can be burned in regular reac­tors. This is the same process that I discussed in Chapter 9 for reprocessing spent nuclear fuel to make MOX that is used in nuclear reactors in France. The stock­piles of plutonium in nuclear weapons is about 260 tonnes, equivalent to about a year’s worth of uranium production (49).

In 1993 the United States and Russia signed a historic agreement known as the Megatons to Megawatts program for Russia to convert 500 tonnes of HEU from warheads to LEU that would be bought by the United States to be used in civil­ian nuclear reactors. A contract was signed in 1994 between the US Enrichment Corporation (USEC) and the Russian counterpart, Technabexport (Tenex), to implement the agreement. As a result, the United States will have bought at least 500 tonnes of HEU converted to reactor fuel by 2013 when the program ends. USEC is also down-blending 174 tonnes of US HEU from weapons stockpiles to make into reactor fuel. This program is producing 10,600 tonnes of uranium annually, the biggest component in making up for the shortfall between mining production and use in reactors (49). As of the end of 2012, nearly 19,000 warheads had been converted into fuel for nuclear reactors, providing half of all nuclear power in the United States, which is about 10% of all electricity produced in the nation (50, 51).

The United States is in the process ofbuilding a plant at the Savannah River in South Carolina with AREVA, the French nuclear company, to convert plutonium in US nuclear weapons to MOX (see Chapter 9). Over 60 tons of plutonium from US nuclear warheads are expected to be eventually converted to MOX fuel at the Savannah River plant.