MISSION
To develop nuclear power technology and to produce Nuclear Power as a safe, environmentally benign and economically viable source of electrical energy to meet the increasing electricity needs of the country. - Nuclear Power Corporation of India Limited [NPCIL]
Dr. Homi Jehangir Bhabha, the founding Father & Chairman of India's Atomic Energy Commission
Let us learn in layman’s language what exactly Nuclear energy means. Nuclear energy is produced by controlled nuclear reactions. In a typical nuclear reactor, the energy released from continuous splitting of atoms of the fuel is harnessed as heat in either gas or water, and is used to produce steam. The steam drives the turbines that produce electricity. Control rods are used to ensure a controlled rate of the nuclear reactions.
Nuclear fission occurs when a larger isotope breaks apart into two or more elements. Scientists usually accomplish this task by bombarding a large isotope with a second, smaller one, commonly a neutron. The collision results in a controlled nuclear fission. Reaction of this type releases a lot of energy. However, during this process, some matter disappears during the nuclear reaction and this loss of matter is called "mass defect". The missing matter is what converted into energy.
Chain reactions and Critical Mass
During nuclear fission of U-235, only one neutron is used, but three are produced, these three neutrons encounter other U-235 atoms and initiate other fission, producing even more neutrons. This process is termed as a “self-sustaining nuclear chain reaction” or in other words, it is a process of continuous nuclear fission.
Isotopes that produce an excess of neutrons in their fission support a chain reaction. This type of isotope is termed as a “fissionable nuclear fuel”, and the two most common fissionable isotopes used during nuclear reactions are Uranium-235 and Plutonium-239. The minimum amount of fissionable material needed to ensure a chain reaction is “critical mass” and anything less than this amount is “sub-critical”.
Atomic bombs
Because of the tremendous amount of energy released in a fission chain reaction, the military implications of nuclear reactions are immense. In an atomic bomb, two fissionable isotopes are kept apart. Each piece, by itself, is sub-critical. When it is time for the bomb to explode, conventional explosives force the two pieces fuse together to cause a critical mass. The chain reaction is uncontrolled, releasing a tremendous amount of energy instantaneously.
