Nuclear Chain Reactions

A chain reaction refers to a process in which neutrons released in fission produce an additional fission in at least one further nucleus. This nucleus in turn produces neutrons, and the process repeats. The process may be controlled (nuclear power) or uncontrolled (nuclear weapons).

If each neutron releases two more neutrons, then the number of fissions doubles each generation. In that case, in 10 generations there are 1,024 fissions and in 80 generations about 6 × 10 23 (a mole) fissions.

Nuclear Chain Reaction
U235 + n → fission + 2 or 3 n + 200 MeV

Energy Released From Each Fission

Kinetic energy of fission products 165 MeV
Gamma rays 7 MeV
Kinetic energy of the neutrons 6 MeV
Energy from fission products MeV
Gamma rays from fission products 6 MeV
Anti-neutrinos from fission products 9 MeV
200 MeV
1 MeV (million electron volts) = 1.609 × 10-13 joules