Uranium is not decomposed by the action of neutrons, but the laws of physics, it should decompose should be a chain reaction of uranium fission, as is the case with plutonium. Why?
in this sim, it seems to use the action of neutron bombardment to spark reactions. though, it is a bit odd because full sized atoms are the same sie as sub-atoms.
Uranium is more similar to what plutonium is in real life, and vice versa. PLUT was renamed URAN when an actually fissile PLUT was added, an eternity ago. I think.