Sources of Energy

This is another important source of energy that is obtained from the energy that is stored in the nucleus of an atom. This stored energy can be obtained by carrying out two types of nuclear reactions called nuclear fission reaction and nuclear fusion reaction.

Nuclear Fission Reaction
The process of splitting of a heavy nucleus into a number of light nuclei with the liberation of tremendous amount of energy and two or three neutrons is called nuclear fission.

• In the fissioning of the Uranium-235 isotope, some mass of Uranium disappears (or is lost) and this small mass gets converted into tremendous amount of energy governed by Einstein's famous mass-energy equation
  
  
• 
  Where E = energy released
  m = difference in mass of the original nucleus and product nuclei
  C = velocity of light [3 x 10⁸ m/s]
  This energy is expressed in terms of electron volt [eV]
  1eV = 1.602 x 10 ¹⁹ Joules
  
  
• The fission of an atom of Uranium produces 10 million times the energy produced by the combustion of an atom of carbon from coal.
  
  
• Nuclear energy is produced in a nuclear reactor which is a device to generate electricity and used Uranium-235 as its fuel. In this reactor the energy released is controlled or sustained which is called as sustained fission reaction. Otherwise the energy goes out of control which becomes an explosive fission reaction. The energy is controlled by retaining just enough neutrons to undergo fission and the excess neutrons are absorbed by the control rods in the reactor.
  
  Principle of Nuclear Power Production
  Nuclear fission which takes place inside the reactor produces tremendous heat. This heat energy is used to boil water to form super-heated steam, which in turn rotates the turbines to generate electricity.
  
  Advantages of Nuclear Power
• Nuclear power is a viable option where fossil fuels like coal are not available
• If operated properly, nuclear power plants produce less atmospheric pollution than thermal power plants
• It consumes very little fuel. It can operate for more than a year without needing new fuel elements
• A sizeable amount of fuel (uranium and plutonium) can be reclaimed by processing the spent fuel material in contrast to fuels like coal which cannot be reclaimed
• Some radioactive byproducts in the process are used in medicine and industry
  
  Disadvantages
• In case of accidents or explosion, the radioactive materials can contaminate vast areas of land, crops, water, people etc
• The number of safety measures that has to be considered before setting up a plant makes the construction of the plant expensive
• The disposal of radioactive wastes in the fission process is a major problem. Expensive long-term storage areas have to be built
• They also pose security problems, as the fuel and the by-products can be used to build nuclear weapons

Nuclear power reactors are located at Tarapur (Maharashtra), Rana Pratap Sagar (Rajasthan), Kalpakkam (Tamil Nadu), Narora (Uttar Pradesh), Kakrapar (Gujrat) and Kaiga (Karnataka)

All these have a capacity of less than 3% of the total electricity generation capacity of our country. However many countries industrialised are meeting more than 3% of their electrical power needs from nuclear reactors.

Conclusion
Currently all commercial reactors are based on nuclear fission. But there is another possibility of nuclear energy generation by a safer process called nuclear fusion.

Nuclear fusion is the combining of two lighter nuclei to form a heavier nucleus, most commonly used are the hydrogen isotopes to create helium. It is the source of energy in the sun. It happens continuously in the atmosphere of the sun and takes place at extremely high temperature of about 4 x 10^{6 o}C. But in the laboratory it can be initiated by using particle accelerators.