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The sun and stars are seemingly inexhaustible sources of energy. That energy is the result of nuclear reactions, in which matter is converted to energy. We have been able to harness that mechanism and regularly use it to generate power. Some people praise the technology as a low-cost, low-emission alternative to fossil fuels, while others stress the negative impact of nuclear waste and accidents such as Three Mile Island and Chernobyl. Nuclear energy is energy in the nucleus (core) of an atom. Atoms are tiny particles that make up every object in the universe. There is enormous energy in the bonds that hold atoms together. Nuclear energy can be used to make electricity. But first the energy must be released. It can be released from atoms in two ways: nuclear fusion and nuclear fission. Unlike the stars, the nuclear reactors that we have today work on the principle of nuclear fission. Scientists are working to make fusion reactors which have the potential of providing more energy with fewer disadvantages of the fission reactors. Presently, nuclear energy provides for approximately 16% of the world's electricity. As of July 2008, there were more than 430 operating nuclear power plants in 31 countries, some depending more on nuclear power than others.
Power plants that depend on atomic energy don't operate that differently from a typical coal-burning power plant. Both heat water into pressurized steam, which drives a turbine generator. The key difference between the two plants is the method of heating the water. While older plants burn fossil fuels, nuclear plants depend on the heat that occurs during nuclear fission (viz. when one atom splits into two). Changes that can occur in the structure of the nuclei of atoms are called nuclear reactions. Energy created in a nuclear reaction is called nuclear energy, or atomic energy. Nuclear energy is produced:-
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