Why is nuclear fission a chain reaction?

1 Answer
Jun 9, 2015

A nuclear fission is a chain reaction because it produces its own reagents, thus allowing more nuclear fissions.

Explanation:

Be a radioactive atom #A# which, when hit by a neuttron #n#, disintegrates into two lighter atoms #B# and #C# and #x# neutrons. The nuclear fission's equation is

#n+A rarr B+C+x*n#

You can see that if one neutron is thrown at a group of atoms #A#, one disintegration will be triggered, releasing #x# neutrons.
Each neutron released by the first reaction can, and probably will, encounter another atom #A# of the group and trigger another disintegration, releasing #x# more neutrons, etc.

Any reaction following the first is a consequence of the previous reaction, due to the previous reaction releasing a reagent of the current reaction. This is a chain reaction.