Thorium is fertile not fissile.
You must bombard it with neutrons and get it to capture them and then wait for it to decay to U233 which is fissile. This means you need U235 or Pu239 as the breeder starter fuel there is no way around this fact. You could use a particle accelerator at unthinkable expense to provide said neutron flux but thorium is not fuel it is breeding material nothing more. If you at a breeding fissile isotopes there is not one better than Pu239 it is the perfect fissile isotope only Np236 has a smaller crit mass and it’s super rare. Again if you are breeding fuel Pu239 is the goal , stop being ninnies about plutonium Jane Fonda is a commie lunatic. The French, Russians and Chinese all reprocess and burn MOX and we should too. There is ten thousand years worth of U238 for breeding just sitting as UF6 in cylinders at enrichment plants as waste right now today we don’t need to mine a single gram more. We need the political will to use the technology the USA invented but Clinton shutdown the IFR it worked flawlessly.
U233 is easier to chemically vs isotopic separate from thorium vs U235 is from U238 or Pu239 from spent fuel.
U233 is all bomb grade from the start unlike U239 which will always have Pu240/241 in reactor spent fuel. It’s never bomb grade. You need dedicated weapons reactors with very short irradiation cycles to make weapons grade Pu , thorium breeders do it as par for the course.
We don’t need new tech we need to have some Fing balls and make IFR reactors at scale.
I have friends and alumni working at Aalo in Austin they are the ones doing sodium cooled reactors for AI centers right now they have a working reactor at the National lab expected to go first crit on July 4th as part of the DOE renaissance program. They fully expect to burn Pu239 in the near future they chose sodium cooling specifically to be able to switch to the fast spectrum as soon as the USA grows a pair of balls.
The problem with PU is that fast neutrons make it split. With reactors that use thermal /or slow neutrons you have more control. If the substance slowing down the neutrons gets hot , less slow neutrons get made so the reactor is self adjusting that way. PU is great for bombs because the fast neutrons continue the reaction quickly so it all gets used up fast. Perfect for bombs!