Introduction: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. Presently, nuclear energy provides for approximately 16% of the world's electricity. Unlike the stars, the nuclear reactors that we have today work on the principle of nuclear fission. Scientists are working like madmen to make fusion reactors which have the potential of providing more energy with fewer disadvantages than fission reactors.
Naturally:Some nuclear energy is produced naturally. For example, the Sun and other stars make heat and light by nuclear reactions.
Man-Made:Nuclear energy can be man-made too. Machines called nuclear reactors, parts of nuclear power plants, provide electricity for many cities. Man-made nuclear reactions also occur in the explosion of atomic and hydrogen bombs.
Nuclear energy is produced in two different ways, in one, large nuclei are split to release energy. In the other method, small nuclei are combined to release energy.
For a more detailed look at nuclear fission and nuclear fusion, consult the nuclear physics page.
1. Nuclear Fission:Heavier nucleus is split into lighter nuclei, on bombardment by fast moving neutrons, and a large amount of energy is released.
E.g.: Fission of U235
- When U235 nucleus is hit by a thermal neutron, it undergoes the following reaction with the release of 3 neutrons.
U92235 n10Ba13956 Kr 9436 3n10 Energy
- Each of the above 3 neutrons strikes another U235 nucleus causing (3x3) 9 subsequent reactions.
- These 9 reactions further give rise to (3x9) 27 reactions.
- This process of propagation of the reaction by multiplication in threes at each fission is called chain reaction.
- Fission reaction of U235 is given below.
92U235 0n1 → 36Kr 92 56Ba141 3 0n1 energy
Nuclear fission-chain reaction
Nuclear fusion: Lighter nucleuses are combined together at extremely high temperatures to form heavier nucleus and a large amount of energy is released.
E.g.: Fusion of H21 .Two hydrogen-2 (Deuterium) atoms may fuse to form helium at 1 billion0C with the release of large amount of energy.
1H2 1H2 → 3He2 0n1 energy
Nuclear power of India:
- Tarapur (Maharashtra
- Ranapratap Sagar (Rajasthan)
- Kalpakkam (Tamilnadu)
- Narora (U.P).
USES OF ALTERNATE (RENEWABLE) ENERGY SOURCES:
Why Alternate (Renewable) Energy Sources are required?
The importance of solar energy can be emphasized particularly in view of the fact that fossil fuels and other conventional sources are not free from environmental implications.
- least pollution, safety and security snags and are universally available have the best enhance of large scale utilization in future
- Hydro-electric power generation is expected to upset the ecological balance existing on earth
- Besides space heating, hydel power plants critically pollute the aquatic and terrestrial biota.
- Radioactive pollutants released from nuclear power plants are chronically hazardous.
- The commissioning of boiling water power reactors (BWRS) have resulted in the critical accumulation of large number of long lived radionuclides in water.