I have never understood why we need Thorium. Surely for the next 100 years or so running out of Uranium isn't an issue. And by the time this becomes an issue fusion or some other esoteric technology may already be working.

To me it seems to be all about the reactor type. If we get high termperature gas cooled reactors or molten salt reactors with simple passive safety systems, then we are on a path to cheap and safe nuclear reactors.