Nuclear fission was first discovered by Otto Hahn when Uranium was split into Ba and Kr.

In nuclear fission heavy nucleus splits into two or more nuclei and a large amount of energy released during the reaction called nuclear energy.

The ratio of ejectile and projectile in the fission

reaction called multiplication factor ( α ) which gives the feasibility of fission reaction.

Some of the released neutrons do not participate in the chain reaction they escape from the out without utilized, Therefore a sufficient amount of radioactive material is needed for the reaction.

This amount is called critical mass of radioactive

substance. The graph of potential energy and

internuclear distance is given as –

(i) A fission reaction becomes spontaneous when –