Nuclear power is any nuclear technology designed to extract usable energy from atomic nuclei via controlled nuclear reactions. Nuclear technology is technology that involves the reactions of atomic nuclei. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom In Nuclear physics, a nuclear reaction is the process in which two nuclei or nuclear particles collide to produce products different from the initial particles The most common method today is through nuclear fission, though other methods include nuclear fusion and radioactive decay. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. All current methods involve heating a working fluid such as water, which is then converted into mechanical work for the purpose of generating electricity or propulsion. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature In Thermodynamics, work is the quantity of Energy transferred from one system to another without an accompanying transfer of Entropy. Nuclear propulsion includes a wide variety of propulsion methods that use some form of Nuclear reaction as their primary power source Today, more than 15% of the world's electricity comes from nuclear power, over 150 nuclear-powered naval vessels have been built, and a few radioisotope rockets have been produced. The radioisotope rocket is a type of Rocket engine that uses the heat generated by the decay of Radioactive elements to heat a Working fluid, which is then
As of 2004, nuclear power provided 6. Nuclear power is a method for generating energy by harnessing the radioactivity of atoms List of nuclear reactors is a comprehensive annotated list of all the Nuclear reactors of the world sorted by country 5% of the world's energy and 15. 7% of the world's electricity, with the U.S., France, and Japan together accounting for 57% of nuclear generated electricity. See also Nuclear power As of 2007 in the United States there are 104 (69 Pressurized water reactors and 35 In France, As of 2002, Électricité de France (EDF — the country's main Electricity generation and distribution company — manages the country's 59 As of 2005, Japan was the third largest nuclear power user in the world with 55 Nuclear reactors accounting for 30% of its electricity generated  As of 2007, the IAEA reported there are 439 nuclear power reactors in operation in the world, operating in 31 countries. The International Atomic Energy Agency ( IAEA) is an international organization that seeks to promote the peaceful use of nuclear energy and to inhibit its 
The United States produces the most nuclear energy, with nuclear power providing 19% of the electricity it consumes, while France produces the highest percentage of its electrical energy from nuclear reactors—78% as of 2006. The United States of America —commonly referred to as the This article is about the country For a topic outline on this subject see List of basic France topics.  In the European Union as a whole, nuclear energy provides 30% of the electricity. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in  Nuclear energy policy differs between European Union countries, and some, such as Austria and Ireland, have no active nuclear power stations. See also Nuclear power Nuclear energy policy is a national and international Policy concerning some or all aspects of Nuclear energy, such as Austria (Österreich ( officially the Republic of Austria (Republik Österreich Ireland (pronounced /ˈaɾlənd/ Éire) is the third largest island in Europe, and the twentieth-largest island in the world In comparison, France has a large number of these plants, with 16 multi-unit stations in current use.
Many military and some civilian (such as some icebreaker) ships use nuclear marine propulsion, a form of nuclear propulsion. An icebreaker is a special purpose Ship or Boat designed to move and navigate through Ice -covered waters Nuclear marine propulsion is propulsion of a ship powered by a Nuclear reactor. Nuclear propulsion includes a wide variety of propulsion methods that use some form of Nuclear reaction as their primary power source  A few space vehicles have been launched using full-fledged nuclear reactors: the Soviet RORSAT series and the American SNAP-10A. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled Radar Ocean Reconnaissance SATellite or RORSAT is the western name given to the Soviet Upravlyaemyj Sputnik Aktivnyj (Управляемый Спутник Активный SNAP-10A was the only Nuclear reactor launched and flight tested by the United States
International research is continuing into safety improvements such as passively safe plants, the use of nuclear fusion, and additional uses of process heat such as hydrogen production (in support of a hydrogen economy), for desalinating sea water, and for use in district heating systems. Passive Nuclear safety describes a safety feature of a Nuclear reactor that does not require operator action or electronic feedback in order to shut down safely in In Physics and Nuclear chemistry, nuclear fusion is the process by which multiple- like charged atomic nuclei join together to form a heavier nucleus Hydrogen is commonly produced by extraction from Hydrocarbon Fossil fuels via a chemical path The hydrogen economy is a proposed method of deriving the Energy needed for Motive power (cars boats airplanes buildings or portable electronics by reacting Desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other Minerals from Water District heating (less commonly called teleheating) is a system for distributing heat generated in a centralized location for residential and commercial heating requirements
Nuclear fission was first experimentally achieved by Enrico Fermi in 1934 when his team bombarded uranium with neutrons. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the  In 1938, German chemists Otto Hahn and Fritz Strassmann, along with Austrian physicists Lise Meitner and Meitner's nephew, Otto Robert Frisch, conducted experiments with the products of neutron-bombarded uranium. Otto Hahn (8 March 1879 &ndash 28 July 1968 was a German Chemist who received the 1944 Nobel Prize in Chemistry for discovering Nuclear fission Friedrich Wilhelm "Fritz" Strassman ( February 22, 1902 - April 22, 1980) was a German chemist who with Lise Meitner (7 or 17 November 1878 &ndash 27 October 1968 was an Austrian born later Swedish physicist who studied Radioactivity and Otto Robert Frisch ( 1 October 1904 &ndash 22 September 1979) Austrian British Physicist. They determined that the relatively tiny neutron split the nucleus of the massive uranium atoms into two roughly equal pieces, which was a surprising result. Numerous scientists, including Leo Szilard who was one of the first, recognized that if fission reactions released additional neutrons, a self-sustaining nuclear chain reaction could result. Leó Szilárd (Szilárd Leó February 11, 1898 – May 30, 1964) was an Hungarian - American Physicist who This spurred scientists in many countries (including the United States, the United Kingdom, France, Germany, and the Soviet Union) to petition their government for support of nuclear fission research.
In the United States, where Fermi and Szilard had both emigrated, this led to the creation of the first man-made reactor, known as Chicago Pile-1, which achieved criticality on December 2, 1942. Chicago Pile-1 ( CP-1) was the world's first artificial Nuclear reactor. Events 1409 - The University of Leipzig opens 1755 - The second Eddystone Lighthouse is destroyed by fire Year 1942 ( MCMXLII) was a Common year starting on Thursday (the link will display the full 1942 calendar of the Gregorian calendar. This work became part of the Manhattan Project, which built large reactors at the Hanford Site (formerly the town of Hanford, Washington) to breed plutonium for use in the first nuclear weapons. The World War II Manhattan Project developed the first Nuclear weapon (atomic bomb The Hanford Site is a decommissioned nuclear production complex on the Columbia River in south-central Washington operated by the United States government Hanford was a small agricultural community in Benton County Washington. A nuclear weapon is an explosive device that derives its destructive force from Nuclear reactions either fission or a combination of fission and fusion. A parallel uranium enrichment effort also was pursued. Enriched uranium is a kind of Uranium in which the percent composition of Uranium-235 has been increased through the process of Isotope separation.
After World War II, the fear that reactor research would encourage the rapid spread of nuclear weapons and technology, combined with what many scientists thought would be a long road of development, created a situation in which reactor research was kept under strict government control and classification. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including In addition, most reactor research centered on purely military purposes.
Electricity was generated for the first time by a nuclear reactor on December 20, 1951 at the EBR-I experimental station near Arco, Idaho, which initially produced about 100 kW (the Arco Reactor was also the first to experience partial meltdown, in 1955). Events 69 - Vespasian, formerly a general under Nero, enters Rome to claim the title of Emperor. Year 1951 ( MCMLI) was a Common year starting on Monday. Events of 1951 January Experimental Breeder Reactor I (EBR-I is a Decommissioned Research reactor and U Arco is a city in Butte County, Idaho, United States. The population was 1026 at the 2000 census. A nuclear meltdown is a term for a severe Nuclear reactor accident In 1952, a report by the Paley Commission (The President's Materials Policy Commission) for President Harry Truman made a "relatively pessimistic" assessment of nuclear power, and called for "aggressive research in the whole field of solar energy. Solar energy is the Light and radiant heat from the Sun that powers Earth 's Climate and Weather and sustains Life " A December 1953 speech by President Dwight Eisenhower, "Atoms for Peace," emphasized the useful harnessing of the atom and set the U. Dwight David "Ike" Eisenhower (October 14 1890 – March 28 1969 was President of the United States from 1953 until 1961 and a five-star general "Atoms for Peace" was the title of a speech delivered by U S. on a course of strong government support for international use of nuclear power.
In 1954, Lewis Strauss, then chairman of the United States Atomic Energy Commission (forerunner of the U. Lewis Lichtenstein Strauss ( January 31, 1896 – January 21, 1974) was an American businessman government department head and US Naval officer The United States Atomic Energy Commission (AEC was an agency of the United States government established after World War II by Congress to foster and control S. Nuclear Regulatory Commission and the United States Department of Energy) spoke of electricity in the future being "too cheap to meter. Nuclear Regulatory Commission (or NRC) is a United States government agency that was established by the Energy Reorganization Act in 1974 and was first The United States Department of Energy ( DOE) is a Cabinet -level department of the United States government responsible for energy policy " While few doubt he was thinking of atomic energy when he made the statement, he may have been referring to hydrogen fusion, rather than uranium fission.  Actually, the consensus of government and business at the time was that nuclear (fission) power might eventually become merely economically competitive with conventional power sources.
On June 27, 1954, the USSRs Obninsk Nuclear Power Plant became the world's first nuclear power plant to generate electricity for a power grid, and produced around 5 megawatts electric power. Events 1358 - Republic of Dubrovnik is founded 1709 - Peter the Great defeats Charles XII of Sweden Year 1954 ( MCMLIV) was a Common year starting on Friday (link will display full 1954 Gregorian calendar) The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 The Nuclear power station Obninsk (Обнинская АЭС Obninskaja AES was a part of the science city Obninsk, about 110 km southwest from Moscow Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power 
In 1955 the United Nations' "First Geneva Conference", then the world's largest gathering of scientists and engineers, met to explore the technology. The United Nations ( UN) is an International organization whose stated aims are to facilitate cooperation in International law, International security In 1957 EURATOM was launched alongside the European Economic Community (the latter is now the European Union). The European Atomic Energy Community (EAEC or Euratom is an international organisation which is semi-independent of but completely controlled by the European Community The European Community (EC is one of the Three pillars of the European Union (EU created under the Maastricht Treaty (1992 The same year also saw the launch of the International Atomic Energy Agency (IAEA). The International Atomic Energy Agency ( IAEA) is an international organization that seeks to promote the peaceful use of nuclear energy and to inhibit its
The world's first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956 with an initial capacity of 50 MW (later 200 MW). Sellafield is a nuclear processing and former electricity generating site close to the village of Seascale on the coast of the Irish Sea in Cumbria England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland  The first commercial nuclear generator to become operational in the United States was the Shippingport Reactor (Pennsylvania, December, 1957). The Shippingport Atomic Power Station, "the world’s first full-scale atomic electric power plant devoted exclusively to peacetime uses" was located near the present-day The Commonwealth of Pennsylvania ( often colloquially referred to as PA (its abbreviation by natives and Northeasterners is a state located in the Northeastern
One of the first organizations to develop nuclear power was the U.S. Navy, for the purpose of propelling submarines and aircraft carriers. A submarine is a Watercraft that can operate independently below water as distinct from a Submersible that has only limited underwater capability An aircraft carrier is a Warship designed with It has a good record in nuclear safety, perhaps because of the stringent demands of Admiral Hyman G. Rickover, who was the driving force behind nuclear marine propulsion as well as the Shippingport Reactor. Admiral Hyman George Rickover, United States Navy, ( January 27, 1900 – July 8, 1986) was known as the "Father of The U. S. Navy has operated more nuclear reactors than any other entity, including the Soviet Navy, with no publicly known major incidents. The Soviet Navy ( Russian: Военно-морской флот СССР Voyenno-morskoy flot SSSR, literally "Naval military forces of the USSR" was The first nuclear-powered submarine, USS Nautilus (SSN-571), was put to sea in December 1954. "Underway on nuclear power" Following her commissioning Nautilus remained dockside for further construction and testing  Two U. S. nuclear submarines, USS Scorpion and Thresher, have been lost at sea. Service history Scorpion's keel was laid 20 August 1958 by the Electric Boat Division of the General Dynamics Corporation in Early career Thresher conducted lengthy sea trials in the western Atlantic and Caribbean Sea areas in 1961 and 1962 These vessels were both lost due to malfunctions in systems not related to the reactor plants. Also, the sites are monitored and no known leakage has occurred from the onboard reactors.
Enrico Fermi and Leó Szilárd in 1955 shared for the nuclear reactor, belatedly granted for the work they had done during the Manhattan Project. Leó Szilárd (Szilárd Leó February 11, 1898 – May 30, 1964) was an Hungarian - American Physicist who
Installed nuclear capacity initially rose relatively quickly, rising from less than 1 gigawatt (GW) in 1960 to 100 GW in the late 1970s, and 300 GW in the late 1980s. The watt (symbol W) is the SI derived unit of power, equal to one Joule of energy per Second. Since the late 1980s worldwide capacity has risen much more slowly, reaching 366 GW in 2005. Between around 1970 and 1990, more than 50 GW of capacity was under construction (peaking at over 150 GW in the late 70s and early 80s) — in 2005, around 25 GW of new capacity was planned. More than two-thirds of all nuclear plants ordered after January 1970 were eventually cancelled. 
During the 1970s and 1980s rising economic costs (related to extended construction times largely due to regulatory changes and pressure-group litigation) and falling fossil fuel prices made nuclear power plants then under construction less attractive. In the 1980s (U. S. ) and 1990s (Europe), flat load growth and electricity liberalization also made the addition of large new baseload capacity unattractive. Electricity liberalization refers to the Liberalization of Electricity markets As electricity supply is a Natural monopoly, this entails complex and costly
The 1973 oil crisis had a significant effect on countries, such as France and Japan, which had relied more heavily on oil for electric generation (39% and 73% respectively) to invest in nuclear power. The 1973 oil crisis began on October 17 1973 when the members of Organization of Arab Petroleum Exporting Countries (OAPEC consisting of the Arab members of  Today, nuclear power supplies about 80% and 30% of the electricity in those countries, respectively.
A general movement against nuclear power arose during the last third of the 20th century, based on the fear of a possible nuclear accident, fears of radiation, nuclear proliferation, and on the opposition to nuclear waste production, transport and final storage. This article covers notable accidents involving nuclear devices and radioactive materials Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation Nuclear proliferation is a term now used to describe the spread of Nuclear weapons, fissile material and weapons-applicable nuclear technology and information to nations Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose Perceived risks on the citizens' health and safety, the 1979 accident at Three Mile Island and the 1986 Chernobyl disaster played a part in stopping new plant construction in many countries, although the public policy organization Brookings Institution suggests that new nuclear units have not been ordered in the U. The Three Mile Island accident of 1979 was the most significant accident in the history of the American commercial Nuclear power generating industry The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Soviet Union. S. because the Institution's research concludes they cost 15–30% more over their lifetime than conventional coal and natural gas fired plants. 
Unlike the Three Mile Island accident, the much more serious Chernobyl accident did not increase regulations affecting Western reactors since the Chernobyl reactors were of the problematic RBMK design only used in the Soviet Union, for example lacking "robust" containment buildings. RBMK is an acronym for the Russian reaktor bolshoy moshchnosti kanalniy (Реактор Большой Мощности Канальный which means "High Power Channel A containment building, in its most common usage is a Steel or reinforced concrete structure enclosing a Nuclear reactor.  Many of these reactors are still in use today. However, changes were made in both the reactors themselves (use of low enriched uranium) and in the control system (prevention of disabling safety systems) to prevent the possibility of a duplicate accident.
An international organization to promote safety awareness and professional development on operators in nuclear facilities was created: WANO; World Association of Nuclear Operators. The World Association of Nuclear Operators (WANO is an international organisation founded in 1989 after the Chernobyl accident to foster international cooperation
Opposition in Ireland, New Zealand and Poland prevented nuclear programs there, while Austria (1978), Sweden (1980) and Italy (1987) (influenced by Chernobyl) voted in referendums to oppose or phase out nuclear power. Ireland ( Irish: Éire, ˈeːrʲə is a country in north-western Europe. New Zealand is an Island country in the south-western Pacific Ocean comprising two main landmasses (the North Island and the South Island Poland (Polska officially the Republic of Poland Austria (Österreich ( officially the Republic of Austria (Republik Österreich "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest
As of 2007, Watts Bar 1, which came on-line in 7 February 1996, was the last U. The Diablo Canyon Power Plant is an electricity-generating Nuclear power plant in San Luis Obispo County, California. See also Nuclear power Nuclear energy policy is a national and international Policy concerning some or all aspects of Nuclear energy, such as Mitigation of global warming involves taking actions to reduce Greenhouse gas emissions and to enhance sinks aimed at reducing the extent of Global warming See also Nuclear debate The economics of new nuclear power plants is a controversial subject since multi-billion dollar investments ride on the choice of an energy The Watts Bar Nuclear Generating Station is a Tennessee Valley Authority (TVA Nuclear reactor used for Electric power generation and Tritium Events 457 - Leo I becomes emperor of the Byzantine Empire. 1074 - Battle of Montesarchio in which the Prince Year 1996 ( MCMXCVI) was a Leap year starting on Monday (link will display full 1996 Gregorian calendar) S. commercial nuclear reactor to go on-line. This is often quoted as evidence of a successful worldwide campaign for nuclear power phase-out. However, political resistance to nuclear power has only ever been successful in New Zealand, and parts of Europe and the Philippines. The Philippines ( Filipino: Pilipinas, officially known as the Republic of the Philippines (fil ''Republika ng Pilipinas'' RP Even in the U. S. and throughout Europe, investment in research and in the nuclear fuel cycle has continued, and some experts predict that electricity shortages, fossil fuel price increases, global warming and heavy metal emissions from fossil fuel use, new technology such as passively safe plants, and national energy security will renew the demand for nuclear power plants. The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages An energy crisis is any great bottleneck (or price Rise) in the supply of energy resources to an economy. Global warming is the increase in the average measured temperature of the Passive Nuclear safety describes a safety feature of a Nuclear reactor that does not require operator action or electronic feedback in order to shut down safely in
Many countries remain active in developing nuclear power, including Japan, China and India, all actively developing both fast and thermal technology, South Korea and the United States, developing thermal technology only, and South Africa and China, developing versions of the Pebble Bed Modular Reactor (PBMR). For a topic outline on this subject see List of basic Japan topics. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country South Korea, officially the Republic of Korea and often referred to as Korea ( Korean: 대한민국 tɛː The Republic of South Africa (also known by other official names) is a country located at the southern tip of the continent of Africa The pebble bed reactor ( PBR) is a graphite- moderated, gas-cooled Nuclear reactor. Several EU member states actively pursue nuclear programs, while some other member states continue to have a ban for the nuclear energy use. Japan has an active nuclear construction program with new units brought on-line in 2005. In the U. S. , three consortia responded in 2004 to the U.S. Department of Energy's solicitation under the Nuclear Power 2010 Program and were awarded matching funds—the Energy Policy Act of 2005 authorized loan guarantees for up to six new reactors, and authorized the Department of Energy to build a reactor based on the Generation IV Very-High-Temperature Reactor concept to produce both electricity and hydrogen. The United States Department of Energy ( DOE) is a Cabinet -level department of the United States government responsible for energy policy The " Nuclear Power 2010 Program " was unveiled by the U The Energy Policy Act of 2005 ( is a statute that was passed by the United States Congress on July 29 2005 and signed into law by President George W The Very High Temperature Reactor is a Generation IV reactor concept that uses a Graphite - moderated Nuclear reactor with a once-through The hydrogen economy is a proposed method of deriving the Energy needed for Motive power (cars boats airplanes buildings or portable electronics by reacting As of the early 21st century, nuclear power is of particular interest to both China and India to serve their rapidly growing economies—both are developing fast breeder reactors. The fast breeder or fast breeder reactor ( FBR) is a Fast neutron reactor designed to breed fuel by producing more Fissile material See also energy development. Energy development is the ongoing effort to provide sufficient Primary energy sources and secondary Energy forms to meet civilization's needs In the energy policy of the United Kingdom it is recognized that there is a likely future energy supply shortfall, which may have to be filled by either new nuclear plant construction or maintaining existing plants beyond their programmed lifetime. For energy use in practice see Energy use and conservation in the United Kingdom The current Energy Policy of the United Kingdom is set
There is a possible impediment to production of nuclear power plants, due to a backlog at Japan Steel Works, the only factory in the world able to manufacture the central part of a nuclear reactor's containment vessel in a single piece, which reduces the risk of a radiation leak. ( is a steel manufacturer founded in Muroran, Hokkaidō, Japan in 1907 The company can only make four per year of the steel forgings, which contain radioactivity in a nuclear reactor. It will double its capacity in the next two years, but still will not be able to meet current global demand promptly. Utilities across the world are submitting orders years in advance of any actual need. Other manufacturers are examining various options, including making the component themselves, or finding ways to make a similar item using alternate methods.  Other solutions include using designs that do not require single piece forged pressure vessles such as CANDU or Sodium-cooled Fast Reactors. The CANDU reactor is a Canadian-invented Pressurized heavy water reactor developed initially in the late 1950s and 1960s by a partnership between Atomic Energy of The Sodium-cooled fast reactor or SFR is a Generation IV reactor project to design an advanced Fast neutron reactor.
Conventional thermal power plants all have a fuel source to provide heat. Examples are gas, coal, or oil. For a nuclear power plant, this heat is provided by nuclear fission inside the nuclear reactor. Nuclear fission is the splitting of the nucleus of an atom into parts (lighter nuclei) often producing Free neutrons and other smaller nuclei which may This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled When a relatively large fissile atomic nucleus is struck by a neutron it forms two or more smaller nuclei as fission products, releasing energy and neutrons in a process called nuclear fission. In Nuclear engineering, a fissile material is one that is capable of sustaining a Chain reaction of Nuclear fission. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. Fission products are the atomic fragments left after a large nucleus fissions. The neutrons then trigger further fission, and so on. When this nuclear chain reaction is controlled, the energy released can be used to heat water, produce steam and drive a turbine that generates electricity. A turbine is a rotary Engine that extracts Energy from a Fluid flow While a nuclear power plant uses the same fuel, uranium-235 or plutonium-239, a nuclear explosive involves an uncontrolled chain reaction, and the rate of fission in a reactor is not capable of reaching sufficient levels to trigger a nuclear explosion because commercial reactor grade nuclear fuel is not enriched to a high enough level. Uranium-235 is an isotope of uranium that differs from the element's other common isotope Uranium-238, by its ability to cause a rapidly expanding fission Plutonium-239 is an Isotope of Plutonium. Plutonium-239 is the primary Fissile isotope used for the production of Nuclear weapons although A nuclear explosive is an Explosive device that derives its energy from Nuclear reactions Almost all nuclear explosive devices that have been designed and produced A nuclear explosion occurs as a result of the rapid release of energy from an intentionally high-speed Nuclear reaction. Enriched uranium is a kind of Uranium in which the percent composition of Uranium-235 has been increased through the process of Isotope separation. Naturally found uranium contains 0. 711% U-235 by mass, the rest being U-238 and trace amounts of other isotopes. Uranium-238 (U-238 is the most common isotope of Uranium found in nature Most reactor fuel is enriched to only 3–4%, but some designs use natural uranium or highly enriched uranium. Reactors for nuclear submarines and large naval surface ships, such as aircraft carriers, commonly use highly enriched uranium. A nuclear submarine is a Submarine powered by Atomic energy. Previously conventional submarines used diesel engines that required air for moving on the Although highly enriched uranium is more expensive, it reduces the frequency of refueling, which is very useful for military vessels. CANDU reactors are able to use unenriched uranium because the heavy water they use as a moderator and coolant does not absorb neutrons like light water does. The CANDU reactor is a Canadian-invented Pressurized heavy water reactor developed initially in the late 1950s and 1960s by a partnership between Atomic Energy of Heavy water is water which contains a higher proportion than normal of the Isotope Deuterium, as deuterium oxide, D2O or ²H2O In Nuclear engineering, a neutron moderator is a medium which reduces the velocity of Fast neutrons thereby turning them into Thermal neutrons capable A coolant is a fluid which flows through a device in order to prevent its overheating transferring the heat produced by the device to other devices that utilize or dissipate it
The chain reaction is controlled through the use of materials that absorb and moderate neutrons. In uranium-fueled reactors, neutrons must be moderated (slowed down) because slow neutrons are more likely to cause fission when colliding with a uranium-235 nucleus. Light water reactors use ordinary water to moderate and cool the reactors. See also Nuclear power "LWR" redirects here See also LWR (disambiguation A light water reactor or LWR is When at operating temperatures if the temperature of the water increases, its density drops, and fewer neutrons passing through it are slowed enough to trigger further reactions. That negative feedback stabilizes the reaction rate. Negative Feedback feeds part of a System 's output inverted into the system's input generally with the result that fluctuations are attenuated
The current types of plants (and their common components) are discussed in the article nuclear reactor technology. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled
A number of other designs for nuclear power generation, the Generation IV reactors, are the subject of active research and may be used for practical power generation in the future. Generation IV reactors (Gen IV are a set of theoretical nuclear reactor designs currently being researched A number of the advanced nuclear reactor designs could also make critical fission reactors much cleaner, much safer and/or much less of a risk to the proliferation of nuclear weapons.
It should be noted that such Generation IV reactors are not necessarily fuel by uranium but by thorium, a more abundant fertile material that decays into U233 after being exposed to neutrons. Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 Such reactors use about 1/300 the amount of fuel to power them. The Liquid Fluoride Reactor is one such example of this. A molten salt reactor (MSR is a type of Nuclear reactor where the primary coolant is a Molten salt.
For the future, design changes are being pursued to lessen the risks of fission reactors; in particular, passively safe plants (such as the ESBWR) are available to be built and inherently safe designs are being pursued. Passive Nuclear safety describes a safety feature of a Nuclear reactor that does not require operator action or electronic feedback in order to shut down safely in The reactor formally known as Economic Simplified Boiling Water Reactor ( ESBWR) is a Passively safe generation III+ reactor which builds on the success Inherent safety is a concept particularly used in the chemical and process industries Fusion reactors, which may be viable in the future, have no risk of explosive radiation-releasing accidents, and even smaller risks than the already extremely small risks associated with nuclear fission. Fusion power is power generated by Nuclear fusion reactions In this kind of reaction two light atomic nuclei fuse Whilst fusion power reactors will produce a very small amount of reasonably short lived, intermediate-level radioactive waste at decommissioning time, as a result of neutron activation of the reactor vessel, they will not produce any high-level, long-lived materials comparable to those produced in a fission reactor. Even this small radioactive waste aspect can be mitigated through the use of low-activation steel alloys for the tokamak vessel. A tokamak is a machine producing a toroidal Magnetic field for confining a plasma.
A nuclear reactor is only part of the life-cycle for nuclear power. The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages The process starts with mining (see Uranium mining). Uranium mining is the process of extraction of Uranium Ore from the ground Uranium mines are underground, open-pit, or in-situ leach mines. Open-pit mining, also known as opencast mining and open-cut mining and strip mining, refers to a method of extracting rock or Minerals In-situ leaching (ISL also called in-situ recovery (ISR or solution mining, is a process of recovering minerals such as Copper and Uranium In any case, the uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. For the falsified documents see Yellowcake forgery. Yellowcakes (also called urania) are Uranium concentrates obtained Here, the yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques. Uranium hexafluoride (UF6 referred to as "hex" in the nuclear industry is a compound used in the Uranium enrichment process that produces Enriched uranium is a kind of Uranium in which the percent composition of Uranium-235 has been increased through the process of Isotope separation. At this point, the enriched uranium, containing more than the natural 0. 7% U-235, is used to make rods of the proper composition and geometry for the particular reactor that the fuel is destined for. The fuel rods will spend about 3 operational cycles (typically 6 years total now) inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away. Spent fuel pool (SFP are storage pools for Spent fuel from Nuclear reactors Typically 40 or more feet deep with the bottom 14 feet equipped with storage racks designed After about 5 years in a cooling pond, the spent fuel is radioactively and thermally cool enough to handle, and it can be moved to dry storage casks or reprocessed.
Uranium is a fairly common element in the Earth's crust. The uranium market, like all commodity markets has a history of volatility moving not only with the standard forces of Supply and demand, but also to whims of Geopolitics Energy development is the ongoing effort to provide sufficient Primary energy sources and secondary Energy forms to meet civilization's needs Uranium (jʊˈreɪniəm is a silvery-gray Metallic Chemical element in the A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Uranium is approximately as common as tin or germanium in Earth's crust, and is about 35 times as common as silver. Tin is a Chemical element with the symbol Sn (stannum and Atomic number 50 Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Uranium is a constituent of most rocks, dirt, and of the oceans. The world's present measured resources of uranium, economically recoverable at a price of 130 USD/kg, are enough to last for some 80 years at current consumption. This represents a higher level of assured resources than is normal for most minerals. On the basis of analogies with other metallic minerals, a doubling of price from present levels could be expected to create about a tenfold increase in measured resources, over time. The fuel's contribution to the overall cost of the electricity produced is relatively small, so even a large fuel price escalation will have relatively little effect on final price. For instance, typically a doubling of the uranium market price would increase the fuel cost for a light water reactor by 26% and the electricity cost about 7%, whereas doubling the price of natural gas would typically add 70% to the price of electricity from that source. At high enough prices, eventually extraction from sources such as granite and seawater become economically feasible. 
Current light water reactors make relatively inefficient use of nuclear fuel, fissioning only the very rare uranium-235 isotope. See also Nuclear power "LWR" redirects here See also LWR (disambiguation A light water reactor or LWR is Nuclear reprocessing can make this waste reusable and more efficient reactor designs allow better use of the available resources. Nuclear reprocessing separates components of Spent nuclear fuel such as Reprocessed uranium Plutonium Minor 
As opposed to current light water reactors which use uranium-235 (0. A breeder reactor is a Nuclear reactor that generates new Fissile or fissionable material at a greater rate than it consumes such material 7% of all natural uranium), fast breeder reactors use uranium-238 (99. 3% of all natural uranium). It has been estimated that there is up to five billion years’ worth of uranium-238 for use in these power plants. 
Breeder technology has been used in several reactors, but the high cost of reprocessing fuel safely requires uranium prices of more than 200 USD/kg before becoming justified economically.  As of December 2005, the only breeder reactor producing power is BN-600 in Beloyarsk, Russia. The electricity output of BN-600 is 600 MW — Russia has planned to build another unit, BN-800, at Beloyarsk nuclear power plant. Also, Japan's Monju reactor is planned for restart (having been shut down since 1995), and both China and India intend to build breeder reactors. is Japan 's only Fast breeder reactor. Located in Tsuruga, Fukui Prefecture in Japan, the reactor began construction in 1985 and first achieved
Another alternative would be to use uranium-233 bred from thorium as fission fuel in the thorium fuel cycle. Thorium (ˈθɔːriəm is a Chemical element with the symbol Th and Atomic number 90 The nuclear fuel cycle, also called nuclear fuel chain, is the progression of Nuclear fuel through a series of differing stages Thorium is about 3. 5 times as common as uranium in the Earth's crust, and has different geographic characteristics. This would extend the total practical fissionable resource base by 450%.  Unlike the breeding of U-238 into plutonium, fast breeder reactors are not necessary — it can be performed satisfactorily in more conventional plants. India has looked into this technology, as it has abundant thorium reserves but little uranium.
Fusion power commonly propose the use of deuterium, an isotope of hydrogen, as fuel and in many current designs also lithium. Fusion power is power generated by Nuclear fusion reactions In this kind of reaction two light atomic nuclei fuse Deuterium, also called heavy hydrogen, is a Stable isotope of Hydrogen with a Natural abundance in the Oceans of Earth Isotopes (Greek isos = "equal" tópos = "site place" are any of the different types of atoms ( Nuclides Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Lithium (ˈlɪθiəm is a Chemical element with the symbol Li and Atomic number 3 Assuming a fusion energy output equal to the current global output and that this does not increase in the future, then the known current lithium reserves would last 3000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years. 
Like all forms of power generation using steam turbines, Nuclear power plants use large amounts of water for cooling. Water is a common Chemical substance that is essential for the survival of all known forms of Life. See also Nuclear debate Nuclear power, as with all power sources has an effect on the environment through the Nuclear fuel cycle, through operation and At Sellafield, which is no longer producing electricity, a maximum of 18,184. Sellafield is a nuclear processing and former electricity generating site close to the village of Seascale on the coast of the Irish Sea in Cumbria 4 m3 a day (over 4 million gallons) and 6,637,306 m3 a year (figures from the Environment Agency) of fresh water from Wast Water is still abstracted to use on site for various processes. Distinguish from Waste water. Wast Water or Wastwater is a Lake in the Lake District National Park, England As with most power plants, two-thirds of the energy produced by a nuclear power plant goes into waste heat (see Carnot cycle), and that heat is carried away from the plant in the water (which remains uncontaminated by radioactivity). The Carnot cycle is a particular Thermodynamic cycle, modeled on the hypothetical Carnot heat engine, proposed by Nicolas Léonard Sadi Carnot in 1824 and The emitted water either is sent into cooling towers where it goes up and is emitted as water droplets (literally a cloud) or is discharged into large bodies of water - cooling ponds, lakes, rivers, or oceans.  Droughts can pose a severe problem by causing the source of cooling water to run out. 
The Palo Verde Nuclear Generating Station near Phoenix, AZ is the only nuclear generating facility in the world that is not located adjacent to a large body of water. The Palo Verde Nuclear Generating Station commonly referred to as Palo Verde Power Plant is a Nuclear power plant located in Tonopah Arizona, about Phoenix (ˈfiːˌnɪks O'odham Skikik, Yavapai Wasinka, Western Apache Fiinigis, Navajo Hoozdo, Instead, it uses treated sewage from several nearby municipalities to meet its cooling water needs, recycling 20 billion US gallons (76,000,000 m³) of wastewater each year.
Like conventional power plants, nuclear power plants generate large quantities of waste heat which is expelled in the condenser, following the turbine. For other Condensers not involving heat transfer see Condenser (disambiguation A steam turbine is a mechanical device that extracts Thermal energy from pressurized Steam, and converts it into useful mechanical work Colocation of plants that can take advantage of this thermal energy has been suggested by Oak Ridge National Laboratory (ORNL) as a way to take advantage of process synergy for added energy efficiency. For the business term see Colocation (business. For collocation methods for the solution of differential equations see Collocation method. Oak Ridge National Laboratory ( ORNL) is a multiprogram science and technology National laboratory managed for the United States Department of Energy by Synergy (from the Greek el-Latn syn-ergo, el συνεργός meaning working together is the term used to describe a situation where the final outcome One example would be to use the power plant steam to produce hydrogen from water.  The hydrogen would cost less, and the nuclear power plant would exhaust less heat into the atmosphere and water vapor, which is a short-lived greenhouse gas.
The safe storage and disposal of nuclear waste is a significant challenge. The most important waste stream from nuclear power plants is spent fuel. A large nuclear reactor produces 3 cubic metres (25–30 tonnes) of spent fuel each year.  It is primarily composed of unconverted uranium as well as significant quantities of transuranic actinides (plutonium and curium, mostly). History of the actinoid series From the earlier known chemical properties of actinium (89 up to uranium (92 indicating a relation to the Transition metals it was generally This article is about the chemical element Curium for the ancient city also called Curium (located in Cyprus see Kourion Curium (ˈkjuːriəm In addition, about 3% of it is made of fission products. The actinides (uranium, plutonium, and curium) are responsible for the bulk of the long term radioactivity, whereas the fission products are responsible for the bulk of the short term radioactivity. 
Spent fuel is highly radioactive and needs to be handled with great care and forethought. However, spent nuclear fuel becomes less radioactive over time. After 40 years, the radiation flux is 99. Radiation flux is a measure of the flow of radiation from a given Radioactive source 9% lower than it was the moment the spent fuel was removed, although still dangerously radioactive. 
Spent fuel rods are stored in shielded basins of water (spent fuel pools), usually located on-site. Spent nuclear fuel, occasionally called used nuclear fuel, is Nuclear fuel that has been irradiated in a Nuclear reactor (usually at a Nuclear power The water provides both cooling for the still-decaying fission products, and shielding from the continuing radioactivity. After a few decades some on-site storage involves moving the now cooler, less radioactive fuel to a dry-storage facility or dry cask storage, where the fuel is stored in steel and concrete containers until its radioactivity decreases naturally ("decays") to levels safe enough for other processing. Dry cask storage is a method of storing high-level Radioactive waste, such as Spent nuclear fuel that has already been cooled in the Spent fuel pool for This interim stage spans years or decades, depending on the type of fuel. Most U. S. waste is currently stored in temporary storage sites requiring oversight, while suitable permanent disposal methods are discussed.
As of 2007, the United States had accumulated more than 50,000 metric tons of spent nuclear fuel from nuclear reactors.  Underground storage at Yucca Mountain in U. S. has been proposed as permanent storage. After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.
The amount of waste can be reduced in several ways, particularly reprocessing. Nuclear power is any Nuclear technology designed to extract usable Energy from atomic nuclei via controlled Nuclear reactions Even so, the remaining waste will be substantially radioactive for at least 300 years even if the actinides are removed, and for up to thousands of years if the actinides are left in. Even with separation of all actinides, and using fast breeder reactors to destroy by transmutation some of the longer-lived non-actinides as well, the waste must be segregated from the environment for one to a few hundred years, and therefore this is properly categorized as a long-term problem. Nuclear transmutation is the conversion of one Chemical element or Isotope into another which occurs through Nuclear reactions Natural transmutation occurs Subcritical reactors or fusion reactors could also reduce the time the waste has to be stored. A Subcritical reactor is a nuclear fission reactor that produces fission without achieving Criticality. Fusion power is power generated by Nuclear fusion reactions In this kind of reaction two light atomic nuclei fuse  It has been argued that the best solution for the nuclear waste is above ground temporary storage since technology is rapidly changing. The current waste may well become a valuable resource in the future.
France is one of the world's most densely populated countries. According to a 2007 story broadcast on 60 Minutes, nuclear power gives France the cleanest air of any industrialized country, and the cheapest electricity in all of Europe. Not to be confused with the BBC news magazine program Sixty Minutes (TV series.  France reprocesses its nuclear waste to reduce its mass and make more energy.  However, the article continues, "Today we stock containers of waste because currently scientists don't know how to reduce or eliminate the toxicity, but maybe in 100 years perhaps scientists will . . . Nuclear waste is an enormously difficult political problem which to date no country has solved. It is, in a sense, the Achilles heel of the nuclear industry . . . If France is unable to solve this issue, says Mandil, then 'I do not see how we can continue our nuclear program. '" Further, reprocessing itself has its critics, such as the Union of Concerned Scientists. History The Union of Concerned Scientists was founded in 1969 by faculty and students of the Massachusetts Institute of Technology, located in Cambridge Massachusetts 
The nuclear industry also produces a volume of low-level radioactive waste in the form of contaminated items like clothing, hand tools, water purifier resins, and (upon decommissioning) the materials of which the reactor itself is built. In the United States, the Nuclear Regulatory Commission has repeatedly attempted to allow low-level materials to be handled as normal waste: landfilled, recycled into consumer items, et cetera. Most low-level waste releases very low levels of radioactivity and is only considered radioactive waste because of its history. For example, according to the standards of the NRC, the radiation released by coffee is enough to treat it as low level waste.
In countries with nuclear power, radioactive wastes comprise less than 1% of total industrial toxic wastes, which remain hazardous indefinitely unless they decompose or are treated so that they are less toxic or, ideally, completely non-toxic.  Overall, nuclear power produces far less waste material than fossil-fuel based power plants. Coal-burning plants are particularly noted for producing large amounts of toxic and mildly radioactive ash due to concentrating naturally occurring metals and radioactive material from the coal. Contrary to popular belief, coal power actually results in more radioactive waste being released into the environment than nuclear power. The population effective dose equivalent from radiation from coal plants is 100 times as much as nuclear plants. 
Reprocessing can potentially recover up to 95% of the remaining uranium and plutonium in spent nuclear fuel, putting it into new mixed oxide fuel. Mixed oxide, or MOX fuel, is a blend of oxides of Plutonium and Natural uranium, Reprocessed uranium, or Depleted uranium which behaves This would produce a reduction in long term radioactivity within the remaining waste, since this is largely short-lived fission products, and reduces its volume by over 90%. Reprocessing of civilian fuel from power reactors is currently done on large scale in Britain, France and (formerly) Russia, will be in China and perhaps India, and is being done on an expanding scale in Japan. The full potential of reprocessing has not been achieved because it requires breeder reactors, which are not yet commercially available. A breeder reactor is a Nuclear reactor that generates new Fissile or fissionable material at a greater rate than it consumes such material France is generally cited as the most successful reprocessor, but it presently only recycles 28% (by mass) of the yearly fuel use, 7% within France and another 21% in Russia. 
Unlike other countries, the US has stopped civilian reprocessing as one part of US non-proliferation policy, since reprocessed material such as plutonium can be used in nuclear weapons. Spent fuel is all currently treated as waste.  In February, 2006, a new U. S. initiative, the Global Nuclear Energy Partnership was announced. The Global Nuclear Energy Partnership (GNEP began as a US proposal announced by United States Secretary of Energy Samuel Bodman on February 6 2006 to form an It would be an international effort to reprocess fuel in a manner making nuclear proliferation unfeasible, while making nuclear power available to developing countries. 
Uranium enrichment produces many tons of depleted uranium (DU) which consists of U-238 with most of the easily fissile U-235 isotope removed. Depleted uranium (DU is Uranium primarily composed of the Isotope Uranium-238 (U-238 Depleted uranium (DU is Uranium primarily composed of the Isotope Uranium-238 (U-238 U-238 is a tough metal with several commercial uses — for example, aircraft production, radiation shielding, and making bullets and armor — as it has a higher density than lead. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly There are concerns that U-238 may lead to health problems in groups exposed to this material excessively, like tank crews and civilians living in areas where large quantities of DU ammunition have been used.
Proponents of nuclear energy argue that nuclear power is a sustainable energy source that reduces carbon emissions and increases energy security by decreasing dependence on foreign oil. Sustainable energy is the provision of energy such that it meets the needs of the present without compromising the ability of future generations to meet their needs Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared  Proponents also claim that the risks of storing waste are small and can be further reduced by the technology in the new reactors and the operational safety record is already good when compared to the other major kinds of power plants.
Critics claim that nuclear power is a potentially dangerous energy source, and dispute whether the risks can be reduced through new technology. Technology is a broad concept that deals with a Species ' usage and knowledge of Tools and Crafts and how it affects a species' ability to control and adapt Critics also point to the problem of storing radioactive waste, the potential for possibly severe radioactive contamination by accident or sabotage, the possibility of nuclear proliferation and the disadvantages of centralized electrical production. Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose Radioactive contamination is the uncontrolled distribution of radioactive material in a given environment Nuclear proliferation is a term now used to describe the spread of Nuclear weapons, fissile material and weapons-applicable nuclear technology and information to nations
Arguments of economics and safety are used by both sides of the debate. See also Nuclear debate The economics of new nuclear power plants is a controversial subject since multi-billion dollar investments ride on the choice of an energy See also Nuclear debate Nuclear safety covers the actions taken to prevent Nuclear and radiation accidents or to limit their consequences
All sources of electrical power sometimes fail, differing only in why, how often, how much, for how long, and how predictably. An intermittent power source is a source of electric Power generation that may be uncontrollably Variable or more intermittent than conventional power sources Even the most reliable giant power plants are intermittent: they fail unexpectedly, often for long periods. 
On 16 July 2007 a severe earthquake hit the Kashiwazaki-Kariwa Nuclear Power Plant in Japan. The is a large modern (housing the world's first ABWR) Nuclear power plant on a 4 The plant with seven units is the largest single nuclear power station in the world. Some release of radioactive material occurred and all of the reactors were shut down and are expected to remain closed for damage verification and repairs for at least one year. 
Nuclear power plants in the U. S. now routinely reach 90% capacity factors (including planned outages), making them suitable for base load power plant operations. Baseload (also base load, or baseload demand) is the minimum amount of power that a utility or distribution company must make available to its customers or the amount  Nuclear plants typically strive to schedule their refuelling and maintenance outages in the spring (when hydropower is at a maximum) and to a lesser extent in the fall (both times when electricity demand is lower than the maximums in summer and winter). Of all 132 U. S. nuclear plants built (52 percent of the 253 originally ordered), 21 percent were prematurely and permanently closed due to reliability or cost problems, while another 27 percent have completely failed for a year or more at least once. Normally operating nuclear plants must shut down, on average, for 39 days every 17 months for refueling and maintenance. 
To cope with such intermittence in the operation of nuclear (and large fossil-fuel power plants) electric utilities must install a reserve margin of extra capacity, roughly 15 percent, some of which must be spinning ready for emergency use. Heavily nuclear-dependent areas are particularly at risk of intermittency because drought or a terrorist incident could close many plants simultaneously. Nuclear terrorism denotes the use or threat of the use of Nuclear weapons or Radiological weapons in acts of Terrorism, including attacks against facilities Also, nuclear plants must instantly shut down in a power failure, for safety reasons, but for nuclear-physics reasons, they can’t be restarted quickly. During the August 2003 Northeast blackout, nine normally operating U. The Northeast Blackout of 2003 was a massive widespread Power outage that occurred throughout parts of the Northeastern and Midwestern United States S. nuclear units had to shut down. Twelve days of slow restart later, their average capacity loss had exceeded 50 percent. For the first three days, when they were most needed, their output was below 3 percent of normal. 
The World Nuclear Association states that "Sun, wind, tides and waves cannot be controlled to provide directly either continuous base-load power, or peak-load power when it is needed. World Nuclear Association (WNA formerly the Uranium Institute, is a confederation of companies connected with Nuclear power production In practical terms they are therefore limited to some 10-20% of the capacity of an electricity grid, and cannot directly be applied as economic substitutes for coal or nuclear power, however important they may become in particular areas with favourable conditions. " "The fundamental problem, especially for electricity supply, is their variable and diffuse nature. This means either that there must be reliable duplicate sources of electricity, or some means of electricity storage on a large scale. Apart from pumped-storage hydro systems, no such means exist at present and nor are any in sight. " "Relatively few places have scope for pumped storage dams close to where the power is needed, and overall efficiency is low. Means of storing large amounts of electricity as such in giant batteries or by other means have not been developed. " (Opponents dispute these claims as discussed in the main article. )
This is a controversial subject, since multi-billion dollar investments ride on the choice of an energy source. See also Nuclear debate The economics of new nuclear power plants is a controversial subject since multi-billion dollar investments ride on the choice of an energy Which power source (generally coal, natural gas, nuclear or wind) is most cost-effective depends on the assumptions used in a particular study — several are quoted in the main article.
Nuclear plants generally have higher capital costs, but in 1983 their operating cost was half that of coal .
In May 2001, The Economist stated that “Nuclear power, once claimed to be too cheap to meter, is now too costly to matter” — cheap to run but very expensive to build. Since then, it has become severalfold costlier still to build, and in a few years, as existing fuel contracts expire, nuclear plants are also expected to become severalfold costlier to run. 
The primary environmental impacts of nuclear power include Uranium mining, radioactive effluent emissions, direct and indirect greenhouse gas emissions (water vapor, CO2, NO2) and waste heat. See also Nuclear debate Nuclear power, as with all power sources has an effect on the environment through the Nuclear fuel cycle, through operation and Uranium mining is the process of extraction of Uranium Ore from the ground Waste heat refers to Heat produced by Machines and industrial processes for which no useful application is found and is regarded as a waste By-product Which power source produces the least amount of greenhouse gases is controversial since renewables also produce indirect greenhouse emissions from sources such as mining and construction. Nuclear generation does not directly produce sulfur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels.
Other issues include disposal of nuclear waste, with high level waste proposed to go in Deep geological repositories and nuclear decommissioning. Radioactive wastes are Waste types containing radioactive Chemical elements that do not have a practical purpose The deep geological repository concept involves the placement of long-lived Radioactive waste, often Spent nuclear fuel, in rooms excavated deep within stable low-permeability The Decommissioning of Nuclear power plants is sometimes referred to as nuclear decommissioning, to mark the difference between 'conventional' decommissioning and dismantling
The topic of nuclear safety covers:
Numerous different and usually redundantly duplicated safety features have been designed into (and in some cases backfitted to) nuclear power plants. In the United States, the Nuclear Regulatory Commission (NRC) has the ultimate responsibility for nuclear safety. Nuclear Regulatory Commission (or NRC) is a United States government agency that was established by the Energy Reorganization Act in 1974 and was first
The International Nuclear Event Scale (INES), developed by the International Atomic Energy Agency (IAEA), is used to communicate the severity of nuclear accidents on a scale of 0 to 7. This article covers notable accidents involving nuclear devices and radioactive materials The International Nuclear Event Scale (INES was introduced in 1990 by the International Atomic Energy Agency (IAEA in order to enable prompt communication of safety This article covers notable accidents involving nuclear devices and radioactive materials The two most well-known events are the Three Mile Island accident and the Chernobyl disaster. The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Soviet Union.
The Chernobyl disaster in 1986 at the Chernobyl Nuclear Power Plant in the Ukrainian Soviet Socialist Republic (now Ukraine) was the worst nuclear accident in history and is the only event to receive an INES score of 7. The Chernobyl disaster was a nuclear reactor accident in the Chernobyl Nuclear Power Plant in the Soviet Union. The VI Lenin Memorial Chernobyl Nuclear Power Station (Чернобыльская АЭС им The Ukrainian Soviet Socialist Republic or the Ukrainian SSR was one of the 15 constituent republics that made up the Former Soviet Union from its Ukraine (Україна Ukrayina, /ukrɑˈjinɑ/ is a country in Eastern Europe. The power excursion and resulting steam explosion and fire spread radioactive contamination across large portions of Europe. The UN report 'CHERNOBYL : THE TRUE SCALE OF THE ACCIDENT' published 2005 concluded that the death toll includes the 50 workers who died of acute radiation syndrome, nine children who died from thyroid cancer, and an estimated 4000 excess cancer deaths in the future. Thyroid cancer refers to any of four kinds of malignant Tumors of the Thyroid gland papillary, follicular, medullary or  This accident occurred due to both the flawed operation of the reactors and critical design flaws in the Soviet RBMK reactors, such as lack of a containment building. This disaster however has led to some "lessons learned" for Western power plants, large improvements in safety at Soviet-designed nuclear power plants and major improvements to the remaining RBMK reactors. 
The 1979 accident at Three Mile Island Unit 2 was the worst civilian nuclear accident outside the Soviet Union (INES score of 5). The Three Mile Island accident of 1979 was the most significant accident in the history of the American commercial Nuclear power generating industry The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 The reactor experienced a partial core meltdown. A nuclear meltdown is a term for a severe Nuclear reactor accident However, according to the NRC, the reactor vessel and containment building were not breached and little radiation was released to the environment, with no significant impact on health or the environment. In a Nuclear power plant, the reactor vessel is a Pressure vessel containing the Coolant and reactor core. Several studies have found no increase in cancer rates. 
Greenpeace has produced a report titled An American Chernobyl: Nuclear “Near Misses” at U.S. Reactors Since 1986 which "reveals that nearly two hundred “near misses” to nuclear meltdowns have occurred in the United States". Greenpeace, originally known as the Greenpeace Foundation, was founded in Vancouver, British Columbia, Canada in 1972 At almost 450 nuclear plants in the world that risk is greatly magnified, they say. This is not to mention numerous incidents, many supposedly unreported, that have occurred. Another report produced by Greenpeace called Nuclear Reactor Hazards: Ongoing Dangers of Operating Nuclear Technology in the 21st Century claims that risk of a major accident has increased in the past years. 
Underlying much of the distrust is the fact that it has often been the case that populations are not informed of hazards from various technologies that may impact on them. For example Brookhaven National Laboratory's leaking of radioactive tritium into community groundwater for up to 12 years which angered the local community, dangerous coverups at the Rocky Flats Nuclear Weapons Plant or the pollution of Anniston, Alabama and other locations by Monsanto that went unreported for four decades, however such mistrust is often misdirected — while the industrial sites that were built to support the Manhattan Project and the Cold War's nuclear arms race in the United States display many cases of significant environmental contamination and other safety concerns, in the US such facilities are operated and regulated completely separately from commercial nuclear power plants. Anniston is a city in Calhoun County in the state of Alabama, United States.
Claims exist that the problems of nuclear waste do not come anywhere close to approaching the problems of fossil fuel waste.  A 2004 article from the BBC states: "The World Health Organization (WHO) says 3 million people are killed worldwide by outdoor air pollution annually from vehicles and industrial emissions, and 1. 6 million indoors through using solid fuel. " In the U. S. alone, fossil fuel waste kills 20,000 people each year.  A coal power plant releases 100 times as much radiation as a nuclear power plant of the same wattage.  It is estimated that during 1982, US coal burning released 155 times as much radioactivity into the atmosphere as the Three Mile Island incident. Three Mile Island Nuclear Generating Station is a civilian Nuclear power plant located on an island (Three Mile Island in the Susquehanna River near Harrisburg  The World Nuclear Association provides a comparison of deaths due to accidents among different forms of energy production. World Nuclear Association (WNA formerly the Uranium Institute, is a confederation of companies connected with Nuclear power production In their comparison, deaths per TW-yr of electricity produced from 1970 to 1992 are quoted as 885 for hydropower, 342 for coal, 85 for natural gas, and 8 for nuclear. 
Most human exposure to radiation comes from natural background radiation. Background radiation is the Ionizing radiation emitted from a variety of natural and artificial Radiation sources Most of the remaining exposure comes from medical procedures. Several large studies in the US, Canada, and Europe have found no evidence of any increase in cancer mortality among people living near nuclear facilities. For example, in 1991, the National Cancer Institute (NCI) of the National Institutes of Health announced that a large-scale study, which evaluated mortality from 16 types of cancer, found no increased incidence of cancer mortality for people living near 62 nuclear installations in the United States. The National Cancer Institute (NCI is part of the United States Federal government's National Institutes of Health. "NIH" redirects here For other meanings of NIH see NIH (disambiguation. The study showed no increase in the incidence of childhood leukemia mortality in the study of surrounding counties after start-up of the nuclear facilities. The NCI study, the broadest of its kind ever conducted, surveyed 900,000 cancer deaths in counties near nuclear facilities. 
Some areas of Britain near industrial facilities, particularly near Sellafield, have displayed elevated childhood leukemia levels, in which children living locally are 10 times more likely to contract the cancer. Sellafield is a nuclear processing and former electricity generating site close to the village of Seascale on the coast of the Irish Sea in Cumbria Leukemia or leukaemia (Greek leukos λευκός, "white" aima αίμα, "blood" is a Cancer of the Blood One study of those near Sellafield has ruled out any contribution from nuclear sources, and the reasons for these increases, or clusters, are unclear. Apart from anything else, the levels of radiation at these sites are orders of magnitude too low to account for the excess incidences reported. An order of magnitude is the class of scale or magnitude of any amount where each class contains values of a fixed ratio to the class preceding it One explanation is viruses or other infectious agents being introduced into a local community by the mass movement of migrant workers.  Likewise, small studies have found an increased incidence of childhood leukemia near some nuclear power plants has been found in Germany and France. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe.  Nonetheless, the results of larger multi-site studies in these countries invalidate the hypothesis of an increased risk of leukemia related to nuclear discharge. The methodology and very small samples in the studies finding an increased incidence has been criticized. 
In December of 2007, it was reported that a study showed that German children who lived near nuclear power plants had a higher rate of cancer than those who did not. However, the study also stated that there was no extra radiation near the nuclear power plants, and scientists were puzzled as to what was causing the higher rate of cancer. 
The US Government is leading a plan to develop small "disposable" nuclear reactors for deployment in developing countries. However, there has been considerable debate about the security and nuclear proliferation risks of such a proposal. Nuclear proliferation is a term now used to describe the spread of Nuclear weapons, fissile material and weapons-applicable nuclear technology and information to nations 
Russia announced in 2007 that construction has started on the first of seven ships which each will carry a 70-megawatt nuclear reactor. The ships will provide power to remote coastal towns, or be sold abroad, and 12 countries, including Algeria and Indonesia, have expressed interest. There is considerable debate about the safety of such "floating" nuclear reactors. 
The Estonian Maritime Academy has developed a project to construct an underwater nuclear reactor off the Baltic Sea coast. The project, submitted to the Estonian Eesti Energia company, proposes the construction of a 1,000-MWt nuclear power plant on a granite shelf of the Muuga Bay. The Head of the Academy has said that the construction of a nuclear reactor on the seabed is completely safe. However, an underwater nuclear power plant would be more costly than a similar land-based project. Local environmentalists have also expressed doubts about the ecological safety of such a giant undertaking on the sea shelf. 
In 2003, New Scientist reported that the US Air Force was contemplating a "nuclear-powered unmanned aircraft", to be airborne for months at a time. New Scientist is a weekly International science magazine and website covering recent developments in science and technology for a general English -speaking 
Nuclear proliferation is the spread of nuclear weapons and related technology to nations not recognized as "Nuclear Weapon States" by the Nuclear Nonproliferation Treaty. The Treaty on the Non-Proliferation of Nuclear Weapons, also Nuclear Non-Proliferation Treaty ( NPT or NNPT) is a Treaty to limit the spread Since the days of the Manhattan Project it has been known that reactors could be used for weapons-development purposes—the first nuclear reactors were developed for exactly this reason—as the operation of a nuclear reactor converts U-238 into plutonium. The World War II Manhattan Project developed the first Nuclear weapon (atomic bomb As a consequence, since the 1950s there have been concerns about the possibility of using reactors as a dual-use technology, whereby apparently peaceful technological development could serve as an approach to nuclear weapons capability. Dual-use is a term often used in Politics and Diplomacy to refer to Technology which can be used for both Peaceful and Military aims
In the US, plants are surrounded by a double row of tall fences which are electronically monitored. The plant grounds are patrolled by a sizeable force of armed guards.  The NRC's "Design Basis Threat" criteria for plants is a secret, and so what size attacking force the plants are able to protect against is unknown. However, to scram a plant takes less than 5 seconds while unimpeded restart takes hours, severely hampering a terrorist force in a goal to release radioactivity. This article is about nuclear reactors For other meanings see Scram (disambiguation.
An additional concern with nuclear power plants is that if the by-products of nuclear fission—the nuclear waste generated by the plant—were to be unprotected it could be used as a radiological weapon, colloquially known as a "dirty bomb". A radiological weapon (or radiological dispersion device, RDD) is any weapon that is designed to spread Radioactive material with the intent to kill and The term dirty bomb is primarily used to refer to a radiological dispersal device ( RDD) a speculative Radiological weapon which combines Radioactive There have been incidents of nuclear plant workers attempting to sell nuclear materials for this purpose (for example, there was such an incident in Russia in 1999 where plant workers attempted to sell 5 grams of radioactive material on the open market, and an incident in 1993 where Russian workers were caught attempting to sell 4. 5 kilograms of enriched uranium. ), and there are additional concerns that the transportation of nuclear waste along roadways or railways opens it up for potential theft. The UN has since called upon world leaders to improve security in order to prevent radioactive material falling into the hands of terrorists, and such fears have been used as justifications for centralized, permanent, and secure waste repositories and increased security along transportation routes. The United Nations ( UN) is an International organization whose stated aims are to facilitate cooperation in International law, International security