For heavy nuclides, it is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments ( heating the bulk material where fission takes place). Frisch named the process by analogy with biological fission of living cells. Meitner explained it theoretically in January 1939 along with her nephew Otto Robert Frisch. Hahn understood that a 'burst' of the atomic nuclei had occurred.
Nuclear fission of heavy elements was discovered on 17 December 1938, by German chemist Otto Hahn and his assistant Fritz Strassmann in cooperation with Austrian-Swedish physicist Lise Meitner.
The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactive decay. Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei.
