Nuclear energy is the newest form of energy i.e. the energy of the latter part of the twentieth century. When the energy is derived from the nucleus of the atom, it is called as the Nuclear or ‘Atomic Energy’.
During the industrial civilization of today, when machines have invaded virtually every aspect of our life, there is a massive growth in the consumption of energy, increasing thereby the pressure on dwindling traditional sources of energy.
Hence an industrial society based primarily on coal, oil and gas cannot go on for long because the fossil fuels cannot be replenished, once they are used up. Coal fills 27% of the global energy budget. At the present rate use, it would carry its resources until the 22nd century. But the picture of oil resource is quite grim. Oil supplies some 134 squads a year at a rate that would exhaust its present reserve in about 30 years.
The energy from the sun, geothermal sources, tidal and wave motions and wind can also be exploited usefully for the long term solutions of the energy crisis. But their contributions are less significant, as the harnessing of energy from these sources is beset by techno-economic problems, as far as their exploitation and distribution is concerned.
Hence, the only pragmatic answer, in this context, to the world’s energy scenario, is *Nuclear energy’. It is the demand of time that the sources of nuclear energy are exploited and are developed to commercially viable level. This development will generate a vast energy source and will be a leader in the progress of various other disciplines like industry, agriculture and medicine.
What is Nuclear Energy
The atom of an element is consisted of Nucleus at the centre and surrounding it, are the electrons. The nucleus is composed of neutrons and protons and is positively charged. Inside the nucleus, the neutrons and protons are binding together by energy. This energy is called ‘binding energy’. If a heavy (UU5 = Uranium 235) nucleus is spitted, it forms smaller nuclei, neutrons and releases the enormous quantity of this binding energy. As this energy is released through splitting of the nucleus, it is called ‘Nuclear energy’ and the splitting process is called as ‘Fission’. The fission reactions are continuous and release more and more neutrons. One of the released neutrons, again, strikes another atom (Uranium-235) for fission. These continuous reactions are called “Nuclear Chain Reactions”. In case of an atom bomb, the chain reaction takes place in such rapidity that it is beyond the capacity to control. Hence, the explosion takes place. But in a nuclear reactor, the chain reaction takes place slowly under controlled conditions and the heat produced in each fission is transformed to electrical energy and radioactivity substances produced are not allowed to escape.
The device for releasing nuclear energy continuously under controlled conditions from the fission process is called a ‘Nuclear Reactor’. Here, the heat produced is converted to a more convenient form of energy, i.e. electricity.
There are mainly two fundamental types of nuclear reactors i.e.
(i) Light-Water-Reactor (LWR), and
(ii) Fast-Breeder-Reactor (FBR)
In case of Light-Water-Reactor, controlled fissions of Uranium-235 takes place inside a core, generating heat. The core is heavily shielded with iron or steel to prevent exposure. In this reactor the speed of neutrons has to be continuously reduced through the use of moderators. Heavy water (formed by deuterium and Oxygen) acts as a very good moderator and coolant.
But, in case of the Fast-Breeder-Re actor (FBR), Uranium-238, the natural or enriched Uranium ore is utilized in place of Uranium-235 as the fission fuel to produce heat. Here plutonium is “bred” by bombarding Uranium-238 with neutrons and produces in large quantities the same kind of fissile materials which it burns i.e., reactor using plutonium as fuel can produce more plutonium than it uses by conversion of Uranium-238 into plutonium. Sodium is used as moderator and coolant in place of water in a Fast-Breeder-Reactor.
Another method of deriving nuclear energy is by fusion of two light nuclei into a heavier nucleus under certain conditions which is just the opposite of fission. The nuclear fusion process known to occur in nature is the formation of a helium nucleus from two light hydrogen nuclei in a series of reactions. But for fusion, the light nuclei must attain very high speed in order to overcome repulsion and that is possible only at very high temperature i.e., 1070° C. That is why fusion reaction is also called ‘Thermo nuclear reaction’. Hydrogen bomb is the best example of uncontrolled fusion reaction. The development of fusion based atomic reactor is under process. Its main drawback is the high temperature operation and cost effectiveness.