Nuclear power

Nuclear power is the use of nuclear reactions that release nuclear energy to generate heat, which most frequently is then used in steam turbines to produce electricity in a nuclear power plant. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions.Presently, the vast majority of electricity from nuclear power is produced by nuclear fission of uranium and plutonium.Nuclear decay processes are used in niche applications such as radioisotope thermoelectric generators.Generating electricity from fusion power remains at the focus of international research.This article mostly deals with nuclear fission power for electricity generation. Civilian nuclear power supplied 2,488 terawatt hours (TWh) of electricity in 2017, equivalent to about 10% of global electricity generation, and was the second largest low-carbon power source after hydroelectricity. As of April 2018, there are 449 civilian fission reactors in the world, with a combined electrical capacity of 394 gigawatt (GW).There are also 58 nuclear power reactors under construction and 154 reactors planned, with a combined capacity of 63 GW and 157 GW, respectively. As of January 2019, 337 more reactors were proposed.Most reactors under construction are generation III reactors in Asia. Nuclear power has one of the lowest levels of fatalities per unit of energy generated compared to other energy sources. Coal, petroleum, natural gas and hydroelectricity each have caused a greater number of fatalities per unit of energy, due to air pollution and accidents.Since its commercialization in the 1970s, nuclear power has prevented about 1.84 million air pollution-related deaths and the emission of about 64 billion tonnes of carbon dioxide equivalent that would have otherwise resulted from the burning of fossil fuels.Accidents in nuclear power plants include the Chernobyl disaster in the Soviet Union in 1986, the Fukushima Daiichi nuclear disaster in Japan in 2011, and the more contained Three Mile Island accident in the United States in 1979.There have also been some nuclear submarine accidents. There is a debate about nuclear power.Proponents, such as the World Nuclear Association and Environmentalists for Nuclear Energy, contend that nuclear power is a safe, sustainable energy source that reduces carbon emissions.Nuclear power opponents, such as Greenpeace and NIRS, contend that nuclear power poses many threats to people and the environment. Collaboration on research and development towards greater efficiency, safety and recycling of spent fuel in future generation IV reactors presently includes Euratom and the co-operation of more than 10 permanent member countries globally. In 1932 physicist Ernest Rutherford discovered that when lithium atoms were 'split' by protons from a proton accelerator, immense amounts of energy were released in accordance with the principle of mass–energy equivalence. However, he and other nuclear physics pioneers Niels Bohr and Albert Einstein believed harnessing the power of the atom for practical purposes anytime in the near future was unlikely. The same year, his doctoral student James Chadwick discovered the neutron, which was immediately recognized as a potential tool for nuclear experimentation because of its lack of an electric charge. Experiments bombarding materials with neutrons led Frédéric and Irène Joliot-Curie to discover induced radioactivity in 1934, which allowed the creation of radium-like elements. Further work by Enrico Fermi in the 1930s focused on using slow neutrons to increase the effectiveness of induced radioactivity. Experiments bombarding uranium with neutrons led Fermi to believe he had created a new, transuranic element, which was dubbed hesperium. 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, as a means of further investigating Fermi's claims.They determined that the relatively tiny neutron split the nucleus of the massive uranium atoms into two roughly equal pieces, contradicting Fermi.This was an extremely surprising result: all other forms of nuclear decay involved only small changes to the mass of the nucleus, whereas this process—dubbed 'fission' as a reference to biology—involved a complete rupture of the nucleus.Numerous scientists, including Leó Szilárd, who was one of the first, recognized that if fission reactions released additional neutrons, a self-sustaining nuclear chain reaction could result. Once this was experimentally confirmed and announced by Frédéric Joliot-Curie in 1939, scientists in many countries (including the United States, the United Kingdom, France, Germany, and the Soviet Union) petitioned their governments for support of nuclear fission research, just on the cusp of World War II, for the development of a nuclear weapon.