Anything you take out of a Thorium-fueled reactor is going to contain Uranium-232 and its decay products, which emit easily-detectable and dangerous to nearby living things gamma radiation. U-232 is much harder to separate out from the useful U-233 (which is the fissile fuel that Thorium is converted into) than Uranium 235 is from Uranium 238, so it is very hard to extract clean safe fissile material from a Thorium reactor.
This means that a Thorium reactor is really hard to get material from for a nuclear explosion. Any material you do extract is going to be screaming "I'm over here" to any nearby gamma ray detector, and will be dangerous to handle.
But if you just wanted to make a dirty bomb by blowing up a small Thorium nuclear plant with conventional explosives, spreading highly radioactive material all over the place, that sounds much more feasible.
This means that a Thorium reactor is really hard to get material from for a nuclear explosion. Any material you do extract is going to be screaming "I'm over here" to any nearby gamma ray detector, and will be dangerous to handle.
But if you just wanted to make a dirty bomb by blowing up a small Thorium nuclear plant with conventional explosives, spreading highly radioactive material all over the place, that sounds much more feasible.