“The MSRE fuel in Oak Ridge would be solidified salts.”
The fuel is U-233 suspended in molten salts.
Not quite what I was talking about - the salt is the fuel, u233 us not suspended in it. With a LFTR, once the LiF-BeF2-ZrF4-UF4 fuel leaves criticality it will cool into a solid that contains both U233 and TH232 salts. U233 is fissile, but not the material of choice for bombs - we have exploded only one if I recall correctly.
So in solid form, it is exceedingly difficult if not impossible to separate U233 salts from with TH salts. Not only that, U233 is a gamma emitter, and therefore easy to find if it walks away. So my point is there is a very low proliferation risk for this tech.
Also, the U233 that starts the reaction is not fuel that sustains the reaction. TH232 caputues a neutron and decays to Pa233, then U233. There is also Yes and not for the U233 being the fuel. So the MSRE technology or LFTR's are poor choices to easily convert to produce bomb material, right?