What happens in a nuclear chain reaction?

Answer 1

When a free neutron collides with an atom of a fissile material, the atom splits into two (or more) atoms of other elements, energy, and one or more free neutrons. These free neutrons then go on to either collide with other atoms of the material, or escape.

A chain reaction occurs when the material is densely packed enough that the generated neutrons outnumber the escaping neutrons, thereby sustaining the fission reaction by initiating more fission reactions.

Answer 2

A neutron (with a certain range of energy -- not too fast, but not too slow) collides with a nucleus of an atom and causes it to split apart. The element (atom) of material is generally very heavy , but not every heavy element will split (fission) when a neutron "hits" it. Uranium-235, Plutonium-238, and 239 are some examples of fissionable material, while something like U232 is not.

When the atom splits apart, it creates two new atoms (both roughly 1/2 the size of the original atom), PLUS a few neutrons. These neutrons have the amount of energy (not too much, not too little) to split more atoms (nearby) of the same element. Those atoms produce more neutrons which split more atoms and so on, and so on.

If enough of the fissionable material is present, in the proper density (so the extra neutrons can encounter many more nucleuses), then the single neutron at the beginning can ideally cause the whole amount of fissionable atoms to split apart -- a chain reaction.

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Answer 3

one uranium reacts with a neutron giving 3 neutron and energythese react with more uranium and continue