Nuclear Power

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Nuclear power Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity. In 2007, the IAEA reported there were 439 nuclear power reactors in operation in the world,operating in 31 countries.Also, more than 150 naval vessels using nuclear propulsion have been built. There
  Nuclear power Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclearpower plants provide about 6% of the world's energy and 13  –  14% of the world's electricity, withthe U.S., France, and Japan together accounting for about 50% of nuclear generated electricity.In 2007, the IAEA reported there were 439 nuclear power reactors in operation in theworld,operating in 31 countries.Also, more than 150 naval vessels using nuclear propulsion havebeen built.There is an ongoing debate about the use of nuclear energy. Proponents, such as the WorldNuclear Association and IAEA, contend that nuclear power is a sustainable energy source thatreduces carbon emissions. [8] Opponents, such as Greenpeace International and NIRS, believe thatnuclear power poses many threats to people and the environment. [9][10][11]  Nuclear power plant accidents include the Chernobyl disaster (1986), Fukushima Daiichi nucleardisaster (2011), and the Three Mile Island accident (1979). [12] There have also been somenuclear-powered submarine mishaps. [13][14][12] However, the safety record of nuclear power isgood when compared with many other energy technologies. [15] Research into safetyimprovements is continuing [16] and nuclear fusion may be used in the future.China has 25 nuclear power reactors under construction, with plans to build many more, [17] whilein the US the licenses of almost half its reactors have been extended to 60 years, [18] and plans tobuild another dozen are under serious consideration. [19] However, Japan's 2011 FukushimaDaiichi nuclear disaster prompted a rethink of nuclear energy policy in many countries. [20]  Germany decided to close all its reactors by 2022, and Italy has banned nuclear power. [20]  Following Fukushima, the International Energy Agency halved its estimate of additional nucleargenerating capacity to be built by 2035. [21]   Use As of 2005, nuclear power provided 6.3% of the world's energy and 15% of the world'selectricity, with the U.S., France, and Japan together accounting for 56.5% of nuclear generatedelectricity. [2] In 2007, the IAEA reported there were 439 nuclear power reactors in operation inthe world, [3] operating in 31 countries. [4] As of December 2009, the world had 436 reactors. [22]  Since commercial nuclear energy began in the mid 1950s, 2008 was the first year that no newnuclear power plant was connected to the grid, although two were connected in 2009. [22][23]  Annual generation of nuclear power has been on a slight downward trend since 2007, decreasing1.8% in 2009 to 2558 TWh with nuclear power meeting 13  –  14% of the world's electricitydemand. [1] One factor in the nuclear power percentage decrease since 2007 has been theprolonged shutdown of large reactors at the Kashiwazaki-Kariwa Nuclear Power Plant in Japanfollowing the Niigata-Chuetsu-Oki earthquake. [1]    The United States produces the most nuclear energy, with nuclear power providing 19% [24] of theelectricity it consumes, while France produces the highest percentage of its electrical energyfrom nuclear reactors  —  80% as of 2006. [25] In the European Union as a whole, nuclear energyprovides 30% of the electricity. [26] Nuclear energy policy differs among European Unioncountries, and some, such as Austria, Estonia, Ireland and Italy, have no active nuclear powerstations. In comparison, France has a large number of these plants, with 16 multi-unit stations incurrent use.In the US, while the coal and gas electricity industry is projected to be worth $85 billion by2013, nuclear power generators are forecast to be worth $18 billion. [27]  Many military and some civilian (such as some icebreaker) ships use nuclear marine propulsion,a form of nuclear propulsion. [28] A few space vehicles have been launched using full-fledgednuclear reactors: the Soviet RORSAT series and the American SNAP-10A.International research is continuing into safety improvements such as passively safe plants, [16]  the use of nuclear fusion, and additional uses of process heat such as hydrogen production (insupport of a hydrogen economy), for desalinating sea water, and for use in district heatingsystems. Nuclear fusion Nuclear fusion reactions have the potential to be safer and generate less radioactive waste thanfission. [29][30] These reactions appear potentially viable, though technically quite difficult andhave yet to be created on a scale that could be used in a functional power plant. Fusion power hasbeen under intense theoretical and experimental investigation since the 1950s. Use in space Both fission and fusion appear promising for space propulsion applications, generating highermission velocities with less reaction mass. This is due to the much higher energy density of nuclear reactions: some 7 orders of magnitude (10,000,000 times) more energetic than thechemical reactions which power the current generation of rockets.Radioactive decay has been used on a relatively small scale (few kW), mostly to power spacemissions and experiments by using radioisotope thermoelectric generators such as thosedeveloped at Idaho National Laboratory. History Origins The pursuit of nuclear energy for electricity generation began soon after the discovery in theearly 20th century that radioactive elements, such as radium, released immense amounts of energy, according to the principle of mass  –  energy equivalence. However, means of harnessing  such energy was impractical, because intensely radioactive elements were, by their very nature,short-lived (high energy release is correlated with short half-lives). However, the dream of harnessing atomic energy was quite strong, even it was dismissed by such fathers of nuclearphysics like Ernest Rutherford as moonshine. This situation, however, changed in the late1930s, with the discovery of nuclear fission.In 1932, James Chadwick discovered the neutron, which was immediately recognized as apotential tool for nuclear experimentation because of its lack of an electric charge.Experimentation with bombardment of materials with neutrons led Frédéric and Irène Joliot-Curie to discover induced radioactivity in 1934, which allowed the creation of radium-likeelements at much less the price of natural radium. Further work by Enrico Fermi in the 1930sfocused 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 he dubbed hesperium.Constructing the core of B-Reactor at Hanford Site during the Manhattan Project.But in 1938, German chemists Otto Hahn [31] and Fritz Strassmann, along with Austrian physicistLise Meitner [32] and Meitner's nephew, Otto Robert Frisch, [33] conducted experiments with theproducts 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 atomsinto two roughly equal pieces, contradicting Fermi. This was an extremely surprising result: allother forms of nuclear decay involved only small changes to the mass of the nucleus, whereasthis process  —  dubbed fission as a reference to biology  —  involved a complete rupture of thenucleus. 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 couldresult. 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, juston the cusp of World War II.In the United States, where Fermi and Szilárd had both emigrated, this led to the creation of thefirst man-made reactor, known as Chicago Pile-1, which achieved criticality on December 2,1942. This work became part of the Manhattan Project, which made enriched uranium and builtlarge reactors to breed plutonium for use in the first nuclear weapons, which were used on thecities of Hiroshima and Nagasaki.   The first light bulbs ever lit by electricity generated by nuclear power at EBR-1 at what is nowIdaho National Laboratory.After World War II, the prospects of using atomic energy for good, rather than simply for war,were greatly advocated as a reason not to keep all nuclear research controlled by militaryorganizations. However, most scientists agreed that civilian nuclear power would take at least adecade to master, and the fact that nuclear reactors also produced weapons-usable plutoniumcreated a situation in which most national governments (such as those in the United States, theUnited Kingdom, Canada, and the USSR) attempted to keep reactor research under strictgovernment control and classification. In the United States, reactor research was conducted bythe U.S. Atomic Energy Commission, primarily at Oak Ridge, Tennessee, Hanford Site, andArgonne National Laboratory.Work in the United States, United Kingdom, Canada, [34] and USSR proceeded over the course of the late 1940s and early 1950s. Electricity was generated for the first time by a nuclear reactor onDecember 20, 1951, at the EBR-I experimental station near Arco, Idaho, which initiallyproduced about 100 kW. Work was also strongly researched in the US on nuclear marinepropulsion, with a test reactor being developed by 1953 (eventually, the USS Nautilus, the firstnuclear-powered submarine, would launch in 1955). In 1953, US President Dwight Eisenhowergave his Atoms for Peace speech at the United Nations, emphasizing the need to develop peaceful uses of nuclear power quickly. This was followed by the 1954 Amendments to theAtomic Energy Act which allowed rapid declassification of U.S. reactor technology andencouraged development by the private sector. Early years
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