A "green" form of nuclear energy

Here (via Pajamas Media) is a fascinating Cosmos Magazine article about thorium-fuelled nuclear reactors. Thorium, unlike the fissionable form of uranium, is available in vast quantities, according to James Hudnall. Thorium is a nuclear material that cannot sustain a chain reaction unaided, and so poses little danger of a meltdown accident. It also produces relatively small quantities of nuclear waste, and the waste it does produce stays radioactive only for a few hundred years, as opposed to thousands of years in the case of a conventional reactor. Burning it in a reactor does not produce plutonium or other "weaponizable" material (which, one suspects, may be why relatively little money has been invested in the technology); a thorium reactor would in fact be a good way of "incinerating" plutonium from surplus nuclear weapons.

The problem in using thorium is how to stop the nuclear reaction from fizzling out. Two possibilities are proposed. First, a small amount of "seed" uranium or plutonium can be inserted in the thorium to serve as a source of neutrons. This kind of fuel combination could be used with existing reactor designs. More radically, it has also been proposed that a thorium reactor could run on neutrons generated by a particle accelerator, rather than by a nuclear reaction. In this type of reactor an uncontrolled chain reaction would be impossible. Such reactors could also be freely sold without any danger of promoting the proliferation of nuclear weapons.