Re: The Tooth Fairy and Molten Salt Thorium Reactors
Yellowcake (U3O8), the minehead product of uranium mining costs US $35 per lb as there's a glut on the market at the moment. Known exploitable reserves at a pricepoint of under $100 per lb are good for about a century of exploitation, probably more without the need to actively explore for more sources. Japanese scientists have carried out proof-of-concept extraction of uranium from seawater, estimated cost US $300 per kilo of metal. There's also reprocessing, at the moment spent PWR fuel contains as much as 2% U-235 after it is removed from a reactor along with some Pu-239 and Pu-240, both of which could be recycled given the will to do so and the facilities. It costs a chunk of money but it vastly reduces the mass and volume of waste needing deep-geological disposal in the future.
Thorium by itself isn't a nuclear fuel, it's not fissile. The most common isotope is Th-232 which can be bred into U-233 which is fissile but only in a very fast nuclear reactor with a much greater neutron flux than a regular water-moderated reactor, and the history of uranium breeders over the past few decades has not been a technological or commercial triumph -- very hot, compact cores with extremely high fast neutron fluxes tend to go wrong in spectacular ways (see Dounreay, Monju, Phenix, SuperPhenix, the fiery Soviet BN-600 et al).
Proposed molten-salt thorium reactors need a kickstarter of several tonnes of U-235 and Pu-239 in the salt to start breeding and burning the magical thorium. U-233 can be substituted but there are only a few tonnes of that material in existence in the world, it is horrendously expensive as it is made in nuclear reactors and it can be used to build functional nuclear weapons (not very good ones but they will work).
Some work has been carried out in pebble-bed reactors using mixed-oxide fuel with thorium; bits of the "peebles" flake off, dust and crumbs, pebbles crack and disintegrate, jamming the mechanisms that should move them through the carbon core (see Chernobyl) where fission and breeding takes place. The Germans are still waiting for their broken pebble-bed reactor to cool down enough so they can start decommissioning it; it was shut down in 1987. Basically any nuclear reactor that relies on moving fuel around at 700 deg C is probably a bad idea, and that's what the molten-salt thorium breeder has to do to work at all.
Folks like the Indians are working on using thorium in regular PWR reactor designs as a mixed-oxide fuel, experiments are taking place in a Norwegian test reactor at the moment to see what happens chemically, physically and radiologically to pellets made from a mix of thorium, uranium and plutonium over a period of years. This is very long-term research though because uranium is cheap and plentiful for at least the operating lifetime of the next generation of new nuclear plants (sixty years and more).
Biting the hand that feeds IT
