> So this Uranium is safe somehow? In as much that it's impossible to achieve supercriticality with a pile of yellowcake? Yeah. At worst, they risk heavy metal

> So this Uranium is safe somehow? In as much that it's impossible to achieve supercriticality with a pile of yellowcake? Yeah. At worst, they risk heavy metal poisoning (as Uranium has effects similar to lead on the human body.) It takes a lot to make an effective weapon out of Uranium. Building a working device requires separating the incredibly rare heavier isotope U-238 from all of the mostly inert U-235. That's what all the controversy about centrifuges in Iran was about: That's the kind of equipment you need to extract fissionable 238 to make a weapon. Uranium isn't even radioactive enough to cause the kind of threat you assume. Materials like Cobalt-60 are far more dangerous, and are the real concern about "dirty bombs," (explosive devices that spread radioactive material, as opposed to a nuclear bomb) but it's far harder to work with, and it's more carefully regulated. The effect of Cobalt-60 without adequate shielding is cancer and eventually radiation sickness. By contrast, the effect of raw Uranium is... to release small amounts of ionized helium gas over billions of years.