The large amount of energy is released from various nuclear fission processes. This release of energy can be occurred in two ways:
1. In a controlled manner
2. In an uncontrolled manner.
UNCONTROLLED RELEASE OF FISSION ENERGY: In this method the sub critical amount of a fissionable material is suddenly made very high super critical so that approximately two or three neutrons are available per nuclear fission. This results into a formation of self-sustained chain reaction which speeds up at a very high rate so that the whole fissionable material gets exploded with in a fraction of a second releasing large amount of energy in the process. This process of explosion of fissionable material with in a fraction of second forms the basis of the production of the atom bomb.
CONTROLLED RELEASE OF FISSION ENERGY: In this method a chain reaction is carried out in a device called nuclear reactor. It is called controlled because on an average one neutron is left from each fission to excite further fission. Thus chain reaction remains steady and with in control. The excess neutrons which are produced as a result of nuclear fission process are absorbed by cadmium rods. In this method neutrons are permitted to pass through moderators to slow down their speed. Most of the energy released is in the form of heat which can be used for various useful purposes. The excellent fuel for these processes is fissionable radioactive materials. The energy released is used to drive turbo-generators for the production of electricity.
