It's relative. It's difficult to shield relative to U-235 (for example), which means that handling raw fuel is more difficult. (It requires robotic manipulators

It's relative. It's difficult to shield relative to U-235 (for example), which means that handling raw fuel is more difficult. (It requires robotic manipulators -- hot cells, "waldos" [0] -- unlike conventional fuels which can be handled manually [1]). This is barely relevant for MSRs, because there is no fuel fabrication step (no fuel pellets). It is a difficulty for solid-fuelled thorium reactors. It's of no importance in nuclear reactors, because there there rest vastly greater amounts of vastly more radioactive monsters. The reason people talk about U-232 is this confusing debate about nuclear weapons -- there's a weak (I think spurious) argument that thorium is weapons-resistant, because the U-232 gamma radiation makes it difficult to machine/work with weapons cores. It's really not relevant to molten-salt reactors. [0] https://en.wikipedia.org/wiki/Remote_manipulator https://en.wikipedia.org/wiki/Remote_manipulator [1] proof by photo: https://inlportal.inl.gov/portal/server.pt?open=514&objID=1269&mode=2&featurestory=DA_528176 https://inlportal.inl.gov/portal/server.pt?open=514&objI...