Nuclear energy is the use of the atom in sustained nuclear fission to generate heat and electricity. In the 1930’s scientist discovered that a nuclear reaction could be created and controlled. This happens when you take a large isotope and collide a second smaller one, commonly a neutron and the splitting of the large isotope is what creates this reaction called nuclear fission. Matter disappears during a nuclear reaction this loss of matter is converted into energy. Einstein accounted for this conversion of matter into energy with the famous equation; Energy equals mass defect times the speed of light squared (E=mc2). A fissionable isotope is one that supports an excess of neurons in there fission to support a chain reaction. The two main fissionable isotopes used during nuclear reactions are uranium-235 and plutonium-239. Critical mass is the absolute minimum fissionable material needed to support a chain reaction
Nuclear power provides 5,7% of the worlds energy and 13% of the worlds electricity in 2012. In the 1930 the discovery of nuclear fission brought about the possibility to harness atomic energy. The discovery of the neutron in 1932 by James Chadwick led Frédéric and Irène Joliot-Curie to discover induced radioactivity in 1934. In 1938, German chemists Otto Hahn and Fritz Strassmann, along with Austrian physicist Lise Meitner and Meitner's nephew, Otto Robert Frisch, conducted experiments with the products of neutron-bombarded uranium. On June 27, 1954, the USSR's Obninsk Nuclear Power Plant became the world's first nuclear power plant to generate electricity for a power grid, and produced around 5 megawatts of electric power.
The three significant accidents in the 50-year history of civil nuclear power generation are: Three Mile Island (USA 1979) where the reactor was severely damaged but radiation was contained and there were no adverse health or environmental consequences Chernobyl (Ukraine 1986) where the destruction of the reactor by steam explosion and fire killed 31 people and had significant health and environmental consequences. Fukushima (Japan 2011) where three old reactors (together with a fourth) were written off and the effects of loss of cooling due to a huge tsunami were inadequately contained.