Nuclear energy is the energy that is trapped inside each atom. The ancient Greeks believed that the smallest part of nature is an atom. But they did not know 2000 years ago that atoms are made up of further smaller particles a nucleus of protons and neutrons, surrounded by electrons, which swirl around the nucleus much like the earth revolves around the sun.
One of the laws of the universe is that matter and energy can neither be created nor destroyed.
But they can be changed in form. Matter can be changed into energy. Albert Einstein’s famous mathematical formula E = mc2 explains this. The equation says: E [energy] equals m [mass] times c2 [c stands for the speed or velocity of light]. This means that it is mass multiplied by the square of the velocity of light.
Scientists used Einstein's equation as the key to unlock atomic energy and to create atomic bombs.
An atom's nucleus can be split apart. This is known as fission. When this is done, a tremendous amount of energy in the form of both heat and light is released by the initiation of a chain reaction. This energy, when slowly released, can be harnessed to generate electricity. When it is released all at once, it results in a tremendous explosion as in an atomic bomb.
Nuclear energy can also be harnessed by fusion. A fusion reaction occurs when two hydrogen atoms combine to produce one helium atom. This reaction takes place at all times in the sun, which provides us with the solar energy. This technology is still at the experimental stage and may become viable in future.
Uranium is the main element required to run a nuclear reactor where energy is extracted. Uranium is mined from many places around the world. It is processed (to get enriched uranium, i.e. the radioactive isotope) into tiny pellets. These pellets are loaded into long rods that are put into the power plant's reactor. Inside the reactor of an atomic power plant, uranium atoms are split apart in controlled chain reaction. Other fissile material includes plutonium and thorium.