[1] https://www.osti.gov/biblio/79078-fGfEfw/webviewable/
Key quote from the weapons folks is: "If the existing weapons were based on uranium-233 instead of plutonium-239, Livermore would not be interested in switching to plutonium."
See also Kang and von Hippel's famous report (pdf) on Thorium weapons potential: https://www.osti.gov/biblio/79078-fGfEfw/webviewable/
Wikipedia:
It is difficult to make a practical nuclear bomb from a thorium reactor's byproducts. According to Alvin Radkowsky, designer of the world's first full-scale atomic electric power plant, "a thorium reactor's plutonium production rate would be less than 2 percent of that of a standard reactor, and the plutonium's isotopic content would make it unsuitable for a nuclear detonation."[13]:11[19] Several uranium-233 bombs have been tested, but the presence of uranium-232 tended to "poison" the uranium-233 in two ways: intense radiation from the uranium-232 made the material difficult to handle, and the uranium-232 led to possible pre-detonation. Separating the uranium-232 from the uranium-233 proved very difficult, although newer laser techniques could facilitate that process.
Summarizing some of the potential benefits, Martin offers his general opinion: "Thorium could provide a clean and effectively limitless source of power while allaying all public concern—weapons proliferation, radioactive pollution, toxic waste, and fuel that is both costly and complicated to process.
https://en.wikipedia.org/wiki/Thorium-based_nuclear_power
We should stop going after the potentially cleanest source of energy because a single US government study claims it is possible to produce weapons out of it. Coincidentally the same entity that owns the most nuclear weapons on Earth. Luckily non of the world leading Thorium researchers that stupid the stop the progress, hopefully this way of energy production becomes a reality in our lifetime.
There are 2 true benefits to thorium over thorium: less long-lived transuranics (but more deeply-penetrating 2.6 MeV gammas from Tl-208) and the ability to have a breeder with slow neutrons (less specific fissile inventory, but more problematic graphite).
The major health threat from any nuclear reactor is large early release dose, which is proportional to power level and power level alone (Watts is proportional to number of atoms fissioning per second). In this, Thorium fuel is very similar to Uranium fuel. Long-term waste ends up in a deep geologic repository in any case. Uranium-Plutonium cycle can breed as well or better than the Thorium-Uranium cycle.
I like thorium a lot. I just don't want people relying on stuff that is factually incorrect to promote it. It's easy to promote without being wrong.