The Megatons to Megawatts Program

Over the last two decades about 10% of the electricity generated on the American power grid came from decommissioned bomb material produced by the Soviet Union during the Cold War. The program to convert Russian bomb-stuff into American power-stuff was officially known as the "Agreement between the Government of the Russian Federation and the Government of the United States of America Concerning the Disposition of Highly-Enriched Uranium Extracted from Nuclear Weapons," but its unofficial title had a catchier ring to it. You can read more about the program here:
The Megatons to Megawatts Program

Less than 1% of natural uranium on Earth is useful for unleashing nuclear power. Some reactor designs can get by with the natural scarcity of fissile uranium, but most require the ratio of (fissile) uranium 235 to (fertile, but non-fissile) uranium 238 to be artificially enriched to about 5% to run. Bombs require enrichment to 90% U-235 for the explosive chain reaction to work, and during the Cold War the Soviet Union stockpiled an enormous quantity of highly enriched uranium (HEU) as a precursor to the manufacture of nuclear and thermonuclear bombs.

What the Soviets actually planned to do with all this uranium isn't exactly clear. By the breakup of the union, Russia had a stockpile of 500 metric tons of HEU, enough to build at least 20,000 nuclear warheads. Short of fending off a fleet of invading alien starships, it's difficult to conceive of any possible justification for that much firepower, and weapons-grade uranium sitting inert in a warehouse wouldn't have done much good strategically or tactically had the Cold War ever gone hot. Since evil invading aliens don't seem to be on the way, American diplomats proposed downblending the weapons-grade stock to reactor-grade uranium, and consuming the converted explosive material in reactors across the United States. Isaiah wasn't far from the mark when he talked about beating swords into plowshares. For the last 20 years Americans have been lighting our houses with the weapons that were meant to destroy them.

Earlier this month the last shipment of downblended reactor fuel arrived from Russia. Since about half of the nuclear industry's supply of low-enriched uranium since 1993 has come from the Megatons to Megawatts program, another source of uranium will need to be found soon to keep the price of nuclear fuel from climbing. A small amount of the American stockpile of HEU has been converted into reactor uranium since the end of the Cold War, but much of it remains the stuff that makes mushroom clouds and fallout rather than the stuff that runs lightbulbs and air conditioners. Both sides of the former Iron Curtain still have hundreds of tons of plutonium, used in the primary stages of thermonuclear weapons, and this has potential for power generation as well. For now, there are many more swords in the arsenal that would better serve us as plowshares.