Isn't that only applicable for Uranium 235 based reactors? Thorium is converted to Uranium 233 and when split the byproducts have an half life of 10s of years, meaning that the radioactivity drops to safe levels in "only" few hundred years.

This is much more manageable.

Anyway, that is to say that nuclear is a spectrum, and the current mainstream tech I believe it is the one that won because of the military applications (and therefore funding) back in the cold-war era.