"The U.S. under President Richard Nixon chose uranium over thorium in part because uranium reactors provided the weapons grade waste that was desirable during the Cold War. That set the stage for a uranium-based nuclear industry."
Please stop suggesting that spent fuel from power reactors is 'weapons grade'. It isn't. Weapons grade plutonium was made in reactors built and operated for that purpose, because it involves removing fuel rods after a few months. In that time, some of the U-238 atoms in the fuel absorb a neutron to become fissile Pu-239, but only a few (less than 7%) of those absorb a second neutron to become non-fissile Pu-240. Since swapping fuel rods means taking light water reactors off-line for several weeks, this is only done every 18 months or so.
Here's Kirk Sorensen explaining the history of the choice of the plutonium-burning liquid sodium reactor over the thorium-burning molten salt reactor:
http://www.youtube.com/watch?v=bbyr7jZOllI 
