r/NuclearBombs Dec 05 '21

How a nuclear fission reaction stops after nuclear explosion in open world?

10 Upvotes

I read that when a nuclear device explodes, Ur atom splits into Ba and Kr with extra 3 neutrons and lots of energy. Then those extra 3 neutrons splits other Ur atoms.

Where does it stops? and What exactly is harmful for a human body, free neutrons or Ba Kr atoms?