Yes, Thorium is not much better in terms of resistance to proliferation, but I think the reality is that threat of commercial reactors being used for for weapon

Yes, Thorium is not much better in terms of resistance to proliferation, but I think the reality is that threat of commercial reactors being used for for weapons making is pretty small. That's not how nations made their weapons arsenals. One point, that is often ignored, about Uranium 232 is that it is super easy to find. Meaning its incredibly easy for the IAEA to say that something containing Uranium 232 was used anywhere or to validate that it did not leave the reactor site. That said, a lesser known program after the Molten Salt Breeder Experiment at Oak Ridge National Laboratory was the Denatured Molten Salt Reactor, that was specifically designed to be more proliferation resistant (they hope proliferation resistant research would keep their program alive, and it did for a little bit). This work actually lives on and the company furthers ahead in building a Molten Salt Reactor (Uranium) is the Canada based Terrestrial Energy. They are building the Integrated Molten Salt Reactor. In both designs you avoid some of these problems you have if you do separation, but rather you just switch to a burner design and burn it all in one big reactor, no piping, no chemical plants and so on. The problem is once you go to a burner, the primary reason why Thorium is an interesting fuel cycle (>2 neutron fission rate) is lost in a burner. That means the extra work to prove that Thorium is safe is just more work that you have to prove safe to the regulator. Pretty much all Molten Salt companies, even when they have met at a Thorium conference (as Terrestrial Energy did), switch to Uranium because of this issue. For those interested, here are some of the presentations about the current companies working on Molten Salt Reactors: - Stable Molten Salt Reactor (https://youtu.be/TvXcoSdXYlk?t=2m40s https://youtu.be/TvXcoSdXYlk?t=2m40s) - Integrated Molten Salt Reactor (https://www.youtube.com/watch?v=OgTgV3Kq49U https://www.youtube.com/watch?v=OgTgV3Kq49U) - Longer term Liquid fluoride thorium reactor (https://www.youtube.com/watch?v=R3lcIvS7cO0 https://www.youtube.com/watch?v=R3lcIvS7cO0)