Is there at any point that uranium become irreversibly unstable? (like it melts and catches on fire burning really slowly)
And here is my suggestion:
This HAS been thrown back heaps of times but that was before ambient heat. Here is my suggestion:
Ambient Radiation, It has the same property's as real life, Like heat it can spread depended on the amount of radioactive particles, say 3 particles of uranium 20 - 30 rads (example) Plutonium is even more radioactive. All particles can absorb radioactivity and become radioactive killing stick man depending on how much he is exposed to. Half Life ( this is the scientific term for radioactive decay) is where radioactive particles will break down and become other less radioactive ones, eg uranium after 5 years becomes LB 210 lead 210 a gamma radiation emitting isotope of lead say 1 -3 minutes in game.