“Thorium-Fueled Automobile Engine Needs Refueling Once a Century,” reads the headline of an October 2013 story in an online trade publication. This fantastic promise is just one part of a modern boomlet in enthusiasm about the energy potential of thorium, a radioactive element that is far more abundant than uranium. Thorium promoters consistently extol its supposed advantages over uranium. News outlets periodically foresee the possibility of "a cheaper, more efficient, and safer form of nuclear power that produces less nuclear waste than today's uranium-based technology."
Actually, though, the United States has tried to develop thorium as an energy source for some 50 years and is still struggling to deal with the legacy of those attempts. In addition to the billions of dollars it spent, mostly fruitlessly, to develop thorium fuels, the US government will have to spend billions more, at numerous federal nuclear sites, to deal with the wastes produced by those efforts. And America’s energy-from-thorium quest now faces an ignominious conclusion: The US Energy Department appears to have lost track of 96 kilograms of uranium 233, a fissile material made from thorium that can be fashioned into a bomb, and is battling the state of Nevada over the proposed dumping of nearly a ton of left-over fissile materials in a government landfill, in apparent violation of international standards.
Early thorium optimism. The energy potential of the element thorium was discovered in 1940 at the University of California at Berkeley, during the very early days of the US nuclear weapons program. Although thorium atoms do not split, researchers found that they will absorb neutrons when irradiated. After that a small fraction of the thorium then transmutes into a fissionable material—uranium 233—that does undergo fission and can therefore be used in a reactor or bomb.
Continue reading at Bulletin of the Atomic Scientists: Thorium: the wonder fuel that wasn’t