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Encyclopedia > Nuclear reactor technology
Core of CROCUS, a small nuclear reactor used for research at the EPFL in Switzerland.
This article is a subarticle of Nuclear power

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled. Image File history File links Download high resolution version (2560x1920, 798 KB) Réacteur CROCUS; expérience CAROUSEL; divers expériences et manips; détecteurs et instruments. ... Image File history File links Download high resolution version (2560x1920, 798 KB) Réacteur CROCUS; expérience CAROUSEL; divers expériences et manips; détecteurs et instruments. ... Species See text. ... Location: Polytechnic of Lausanne, in western Switzerland The École Polytechnique Fédérale de Lausanne (EPFL) is the Swiss Federal Institute of Technology in Lausanne, Switzerland. ... This article is about applications of nuclear fission reactors as power sources. ... A schematic nuclear fission chain reaction. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, in 1945 lifted nuclear fallout some 18 km (60,000 feet) above the epicenter. ...


The most significant use of nuclear reactors is as an energy source for the generation of electrical power (see Nuclear power) and for the power in some ships (see Nuclear marine propulsion). This is usually accomplished by methods that involve using heat from the nuclear reaction to power steam turbines. There are also other less common uses as discussed below. For delivered electrical power, see Electrical power industry. ... This article is about applications of nuclear fission reactors as power sources. ... This article does not adequately cite its references or sources. ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ...

Contents

How it works

NC State's PULSTAR Reactor is a 1 MW pool-type research reactor with 4% enriched, pin-type fuel consisting of UO2 pellets in zircaloy cladding.
The control room of NC State's Pulstar Nuclear Reactor.

The key components common to most types of nuclear power plants Download high resolution version (480x640, 335 KB)Pulstar Nuclear Reactor. ... Download high resolution version (480x640, 335 KB)Pulstar Nuclear Reactor. ... North Carolina State University is a public, coeducational, extensive research university located in Raleigh, North Carolina, United States. ... Research reactors comprise a wide range of civil and commercial nuclear reactors which are generally not used for power generation. ... Zircaloy, also incorrectly called zircalloy, is a group of of high-zirconium alloys. ... Download high resolution version (439x601, 274 KB)Pulstar Nuclear Reactor. ... Download high resolution version (439x601, 274 KB)Pulstar Nuclear Reactor. ... North Carolina State University is a public, coeducational, extensive research university located in Raleigh, North Carolina, United States. ...

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. When a relatively large fissile atomic nucleus (usually uranium-235 or plutonium-239) 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. 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. It should be noted that 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 (even if the fission reactions increased to a point of being out of control, it would melt the reactor assembly rather than form a nuclear explosion). Enriched uranium is uranium in which the percent composition of uranium-235 has been increased from that of uranium found in nature. Natural uranium is only 0.72% uranium-235, with the rest being mostly uranium-238 (99.2745%) and a tiny fraction is uranium-234 (0.0055%). This does not cite any references or sources. ... A coolant, or heat transfer fluid, 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. ... A control rod is a rod made of a chemical element capable of absorbing many neutrons without decaying themselves. ... Steel Pressure Vessel A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. ... An Emergency Core Cooling System (ECCS) is a component in nuclear power plants designed to deal with a loss of coolant (LOCA) by providing massive backup sources of coolant. ... A reactor protective system (RPS) is a set of components in a nuclear power plant designed to safely shutdown the reactor and prevent the release of radioactive materials. ... Steam generators are systems used to to convert water into steam from heat produced in a nuclear reactor core. ... A boiling water reactor (BWR) is a light water reactor design used in some nuclear power stations. ... A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. ... A boiler feedwater pump is a specific type of pump used to pump water into a steam boiler. ... A rotor of a modern steam turbine, used in a power plant A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into useful mechanical work. ... This article is about machines that produce electricity. ... Condenser refers here to the shell and tube heat exchanger installed at the outlet of every steam turbine in Thermal power stations of utility companies generally. ... An induced nuclear fission event. ... This article or section should include material from Fissile material 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 small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... This article or section does not adequately cite its references or sources. ... Fission products are the residues of fission processes. ... An induced nuclear fission event. ... A schematic nuclear fission chain reaction. ... A Siemens steam turbine with the case opened. ... A nuclear explosive is an explosive device that derives its energy from nuclear reactions. ... It has been suggested that Nuclear explosive be merged into this article or section. ... Three Mile Island Nuclear Generating Station consisted of two pressurized water reactors manufactured by Babcock & Wilcox each inside its own containment building and connected cooling towers. ... These pie-graphs showing the relative proportions of uranium-238 (blue) and uranium-235 (red) at different levels of enrichment. ... There are two objects with this name: Unterseeboot 238 Uranium-238, the most common isotope of uranium This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... U-234 is an isotope of uranium. ...


Reactor types

Classifications

Nuclear Reactors are classified by several methods, a brief outline of these classification schemes is provided.


Classification by type of nuclear reaction

  • Nuclear fission. Most reactors, and all commercial ones, are based on nuclear fission. They generally use uranium as fuel, but research on using thorium is ongoing. This article assumes that the technology is nuclear fission unless otherwise stated. Fission reactors can be divided roughly into two classes, depending on the energy of the neutrons that are used to sustain the fission chain reaction:
    • Thermal reactors use slow or thermal neutrons. Most power reactors are of this type. These are characterized by neutron moderator materials that slow neutrons until they approach the average kinetic energy of the surrounding particles, that is, until they are thermalized. Thermal neutrons have a far higher probability of fissioning uranium-235, and a lower probability of capture by uranium-238 than the faster neutrons that result from fission. As well as the moderator, thermal reactors have fuel (fissionable material), containments, pressure vessels, shielding, and instrumentation to monitor and control the reactor's systems.
    • Neutrons of intermediate energies are less useful because plutonium-239 has a high ratio of capture cross section vs. fission cross section at these energies, impairing neutron economy. Uranium-233 has low capture/fission ratios across the neutron energy spectrum, so the thorium cycle can use intermediate neutron energies.
    • Fast neutron reactors use fast neutrons to sustain the fission chain reaction. They are characterized by an absence of moderating material. Initiating the chain reaction requires enriched uranium (and/or enrichment with plutonium 239), due to the lower probability of fissioning U-235, and a higher probability of capture by U-238 (as compared to a moderated, thermal neutron). Fast reactors have the potential to produce less transuranic waste because all actinides are fissionable with fast neutrons, but they are more difficult to build and more expensive to operate. Overall, fast reactors are less common than thermal reactors in most applications. Some early power stations were fast reactors, as are some Russian naval propulsion units. Construction of prototypes is continuing (see fast breeder or generation IV reactors).
  • Nuclear fusion. Fusion power is an experimental technology, generally with hydrogen as fuel. While not currently suitable for power production, Farnsworth-Hirsch fusors are used to produce neutron radiation.
  • Radioactive decay. Examples include radioisotope thermoelectric generators and atomic batteries, which generate heat and power by exploiting passive radioactive decay.

An induced nuclear fission event. ... This article is about the chemical element. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight 232. ... A thermal reactor is the most common category of nuclear reactor. ... This article does not cite its references or sources. ... This does not cite any references or sources. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... Uranium-233 is a fissile artificial isotope of uranium, which is proposed as a nuclear fuel. ... The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. ... Shevchenko BN350 nuclear fast reactor and desalination plant situated on the shore of the Caspian Sea. ... A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (10 TJ/kg, hence a speed of 14,000 km/s. ... This does not cite any references or sources. ... These pie-graphs showing the relative proportions of uranium-238 (blue) and uranium-235 (red) at different levels of enrichment. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery white Atomic mass (244) g/mol Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ... There are two objects with this name: Unterseeboot 238 Uranium-238, the most common isotope of uranium This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... This article does not cite its references or sources. ... In chemistry, transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, the atomic number of Uranium. ... The actinide series encompasses the 14 chemical elements that lie between actinium and nobelium on the periodic table with atomic numbers 89 - 102 inclusive. ... The fast breeder or fast breeder reactor (FBR) is a type of fast neutron reactor that produces more fissile material than it consumes. ... Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. ... The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... This article is about the chemistry of hydrogen. ... US3386883 - fusor -- June 4, 1968 The Farnsworth-Hirsch Fusor, or simply fusor, is an apparatus designed by Philo T. Farnsworth to create nuclear fusion. ... Neutron radiation consists of free neutrons. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... // A radioisotope thermoelectric generator (RTG) is a simple electrical generator which obtains its power from radioactive decay. ... The terms atomic battery, nuclear battery and radioisotope battery are used to describe a device which uses the charged particle emissions from a radioactive isotope to directly generate electricity. ...

Classification by moderator material

Used by thermal reactors.

  • Graphite moderated reactors
  • Water moderated reactors
    • Heavy Water moderated reactors
    • Light water moderated reactors (LWRs). Light water reactors use ordinary water to moderate and cool the reactors. 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. Graphite and heavy water reactors tend to be more thoroughly thermalised than light water reactors. Due to the extra thermalization, these types can use natural uranium/unenriched fuel.
  • Light element moderated reactors. These reactors are moderated by Lithum or Beryllium.
    • Molten Salt Reactors (MSRs) are moderated by a light elements such as Li or Be, which are constituents of the coolant/fuel matrix salts LiF and BeF2.
    • Liquid metal cooled reactors, such as one whose coolant in a mixture of Lead and Bismuth, may use BeO as a moderator.

There are several types of graphite moderated nuclear reactors that have been used in commercial electricity generation: Gas-cooled reactors Magnox Advanced gas-cooled reactor (AGR) Water-cooled reactors RBMK High temperature gas-cooled reactors (past) Dragon reactor AVR Peach Bottom Atomic Power Station, Unit 1 THTR-300 Fort St. ... Heavy water reactors use heavy water as a neutron moderator. ... A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water, also called light water, as its neutron moderator. ... This article does not cite any references or sources. ... Natural uranium (NU) refers to refined uranium with the same isotopic ratios as found in nature. ... Molten salt reactor scheme. ... A Liquid metal cooled nuclear reactor is nuclear reactor where the primary coolant is a liquid molten metal. ...

Classification by coolant

In thermal nuclear reactors (LWRs in specific), the coolant acts as a moderator that must slow down the neutrons before they can be efficiently absorbed by the fuel.
  • Water cooled reactor
    • Pressurized water reactor (PWR)
      • A primary characteristic of PWRs is a pressurizer, a specialized pressure vessel. Most commercial PWRs and naval reactors use pressurizers. During normal operation, a pressurizer is partially filled with water, and a steam bubble is maintained above it by heating the water with submerged heaters. During normal operation, the pressurizer is connected to the primary reactor pressure vessel (RPV) and the pressurizer "bubble" provides an expansion space for changes in water volume in the reactor. This arrangement also provides a means of pressure control for the reactor by increasing or decreasing the steam pressure in the pressurizer using the pressurizer heaters. Pressurizers may be isolated from reactor pressure vessel during special maintenance or tests.
      • Pressurised channels. Channel-type reactors can be refuelled under load.
    • Boiling water reactor (BWR)
      • BWRs are characterized by boiling water around the fuel rods in the lower portion of primary reactor pressure vessel. During normal operation, pressure control is accomplished by controlling the amount of steam flowing from the reactor pressure vessel to the turbine.
    • Pool-type reactor
  • Liquid metal cooled reactor. Since water is a moderator, it cannot be used as a coolant in a fast reactor. All fast neutron reactors that have been used for power generation have been liquid metal cooled reactors, but research continues in gas cooled reactors.
  • Gas cooled reactors are cooled by a circulating inert gas, usually helium. Nitrogen and carbon dioxide have also been used. Utilization of the heat varies, depending on the reactor. Some reactors run hot enough that the gas can directly power a gas turbine. Older designs usually run the gas through a heat exchanger to make steam for a steam turbine.
  • Molten Salt Reactors (MSRs) are cooled by circulating a molten salt, typically an eutectic mixture of fluoride salts, such as LiF and BeF2. In a typical MSR, the coolant is also used a matrix in which the fissile material is dissolved.

Download high resolution version (1000x714, 81 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1000x714, 81 KB) Wikipedia does not have an article with this exact name. ... Pressurized water reactors (PWRs) (also VVER if of Russian design) are generation II nuclear power reactors that use ordinary water under high pressure as coolant and neutron moderator. ... Steel Pressure Vessel A pressure vessel is a closed, rigid container designed to hold gases or liquids at a pressure different from the ambient pressure. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Pool-type reactors are a type of nuclear reactor that has a core immersed in an open pool of water. ... A Liquid metal cooled nuclear reactor is nuclear reactor where the primary coolant is a liquid molten metal. ... A Gas Cooled Reactor (more commonly called a GCR) is a generation I nuclear power plant that uses graphite as a neutron moderator and carbon dioxide as coolant. ... For other uses, see Helium (disambiguation). ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ... Molten salt reactor scheme. ...

Classification by generation

A generation II reactor is a nuclear reactor of one of several types developed from the first generation I reactors. ... A generation II reactor is a nuclear power reactor of one of several types developed from the first generation I reactors. ... A generation III reactor is a development of any of the generation II nuclear reactor designs incorporating evolutionary improvements in design which have been developed during the lifetime of the generation II reactor designs, such as improved fuel technology, passive safety systems and standardised design. ... Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. ...

Classification by phase of fuel

Gaseous fission reactors are a hypothetical type of nuclear reactor proposed for use in space travel. ...

Classification by use

A power station (also power plant) is a facility for the generation of electric power. ... Nuclear propulsion can include a wide variety of methods, the commonality of which is the use of some form of nuclear reaction as their primary power source. ... This article does not adequately cite its references or sources. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is used to change the velocity of spacecraft and artificial satellites, or in short, to provide delta-v. ... Shevchenko BN350 desalination unit situated on the shore of the Caspian Sea. ... HVAC may also stand for High-voltage alternating current HVAC is an initialism that stands for heating, ventilation and air-conditioning. This is sometimes referred to as climate control. ... A hydrogen economy is a hypothetical economy in which the energy needed for motive power (for automobiles or other vehicle types) or electricity (for stationary applications) is derived from reacting hydrogen (H2) with oxygen. ... // Transmutation is the conversion of one object into another. ... A breeder reactor is a nuclear reactor that breeds fuel. ... The fast breeder or fast breeder reactor (FBR) is a fast neutron reactor designed to breed fuel by producing more fissile material than it consumes. ... Fertile may be used in the following conrtext: Fertility, a term used to describe the ability of people or animals to produce healthy offspring. ... There are two objects with this name: Unterseeboot 238 Uranium-238, the most common isotope of uranium This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... This article or section should be merged with Fissile Fissile material is composed of atoms that can undergo nuclear fission and sustain a fission chain reaction. ... Natural uranium (NU) refers to refined uranium with the same isotopic ratios as found in nature. ... Depleted uranium storage yard. ... For other uses, see Radiation (disambiguation). ... For other uses, see Isotope (disambiguation). ... General Name, Symbol, Number americium, Am, 95 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass (243) g/mol Electron configuration [Rn] 5f7 7s2 Electrons per shell 2, 8, 18, 32, 25, 8, 2 Physical properties Phase solid Density (near r. ... A smoke detector or smoke alarm is a device that detects smoke and issues an alarm to alert nearby people that there is a potential fire. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter A nuclear weapon derives its destructive force from nuclear reactions of fusion or fission. ... Weapons-grade means that a substance is pure enough to be used to make a weapon or has properties that make it suitable for weapons use. ... This article is about the radioactive element. ... Neutron radiation consists of free neutrons. ... Positron emission is a type of beta decay, sometimes referred to as beta plus (β+). In beta plus decay, a proton is converted to a neutron via the weak nuclear force and a beta plus particle (a positron) and a neutrino are emitted. ... // How Neutron Activation Analysis Works Neutron Activation Analysis (NAA) is a nuclear process used for determining certain concentrations of elements in a vast amount of materials. ... Potassium-argon or K-Ar dating is a geochronological method used in many geoscience disciplines. ... Research reactors comprise a wide range of civil and commercial nuclear reactors which are generally not used for power generation. ...

Current technologies

There are two types of nuclear power in current use:

  1. The nuclear fission reactor produces heat through a controlled nuclear chain reaction in a critical mass of fissile material.
    All current nuclear power plants are critical fission reactors, which are the focus of this article. The output of fission reactors is controllable. There are several subtypes of critical fission reactors, which can be classified as Generation I, Generation II and Generation III. All reactors will be compared to the Pressurized Water Reactor (PWR), as that is the standard modern reactor design.
  1. A. Pressurized Water Reactors (PWR)
    These are reactors cooled and moderated by high pressure liquid (even at extreme temperatures) water. They are the majority of current reactors, and are generally considered the safest and most reliable technology currently in large scale deployment, although Three Mile Island (known for the Harrisburg accident) is a reactor of this type. This is a thermal neutron reactor design, the newest of which are the Advanced Pressurized Water Reactor and the European Pressurized Reactor. United States Naval reactors are of this type.
  1. B. Boiling Water Reactors (BWR)
    These are reactors cooled and moderated by water, under slightly lower pressure. The water is allowed to boil in the reactor. The thermal efficiency of these reactors can be higher, and they can be simpler, and even potentially more stable and safe. These reactors make up a substantial percentage of modern reactors. This is a thermal neutron reactor design, the newest of which are the Advanced Boiling Water Reactor and the Economic Simplified Boiling Water Reactor.
    C. Pressurized Heavy Water Reactor (PHWR)
The Candu Qinshan Nuclear Power Plant
  1. A Canadian design, (known as CANDU) these reactors are heavy-water-cooled and -moderated Pressurized-Water reactors. Instead of using a single large pressure vessel as in a PWR, the fuel is contained in hundreds of pressure tubes. These reactors are fuelled with natural uranium and are thermal neutron reactor designs. PHWRs can be refueled while at full power, which makes them very efficient in their use of uranium (it allows for precise flux control in the core). CANDU PHWR's have been built in Canada, Argentina, China, India (pre-NPT), Pakistan (pre-NPT), Romania, and South Korea. India also operates a number of PHWR's, often termed 'CANDU-derivatives', built after the 1974 Smiling Buddha nuclear weapon test.
The Ignalina Nuclear Power Plant - a still operating RBMK
  1. D. Reaktor Bolshoy Moshchnosti Kanalniy (High Power Channel Reactor) (RBMK)
    A Soviet Union design, built to produce plutonium as well as power. RBMKs are water cooled with a graphite moderator. RBMKs are in some respects similar to CANDU in that they are refuelable On-Load and employ a pressure tube design instead of a PWR-style pressure vessel. However, unlike CANDU they are very unstable and too large to have containment buildings making them dangerous in the case of an accident. A series of critical safety flaws have also been identified with the RBMK design, though some of these were corrected following the Chernobyl accident. RBMK reactors are generally considered one of the most dangerous reactor designs in use. The Chernobyl plant had four RBMK reactors.
  1. E. Gas Cooled Reactor (GCR) and Advanced Gas Cooled Reactor (AGCR)
    These are generally graphite moderated and CO2 cooled. They can have a high thermal efficiency compared with PWRs due to higher operating temperatures. There are a number of operating reactors of this design, mostly in the United Kingdom, where the concept was developed. Older designs (i.e. Magnox stations) are either shut down or will be in the near future. However, the AGCRs have an anticipated life of a further 10 to 20 years. This is a thermal neutron reactor design. Decommissioning costs can be high due to large volume of reactor core.
    F. Liquid Metal Fast Breeder Reactor (LMFBR)
The Superphenix, one of the few FBRs
  1. This is a reactor design that is cooled by liquid metal, totally unmoderated, and produces more fuel than it consumes. These reactors can function much like a PWR in terms of efficiency, and do not require much high pressure containment, as the liquid metal does not need to be kept at high pressure, even at very high temperatures. Superphénix in France was a reactor of this type, as was Fermi-I in the United States. The Monju reactor in Japan suffered a sodium leak in 1995 and is approved for restart in 2008. All three use/used liquid sodium. These reactors are fast neutron, not thermal neutron designs. These reactors come in two types:
    Lead cooled
    Using lead as the liquid metal provides excellent radiation shielding, and allows for operation at very high temperatures. Also, lead is (mostly) transparent to neutrons, so fewer neutrons are lost in the coolant, and the coolant does not become radioactive. Unlike sodium, lead is mostly inert, so there is less risk of explosion or accident, but such large quantities of lead may be problematic from toxicology and disposal points of view. Often a reactor of this type would use a lead-bismuth eutectic mixture. In this case, the bismuth would present some minor radiation problems, as it is not quite as transparent to neutrons, and can be transmuted to a radioactive isotope more readily than lead.
    Sodium cooled
    Most LMFBRs are of this type. The sodium is relatively easy to obtain and work with, and it also manages to actually prevent corrosion on the various reactor parts immersed in it. However, sodium explodes violently when exposed to water, so care must be taken, but such explosions wouldn't be vastly more violent than (for example) a leak of superheated fluid from a SCWR or PWR.
    G. Aqueous Homogeneous Reactor
  2. The radioisotope thermoelectric generator produces heat through passive radioactive decay.
    Some radioisotope thermoelectric generators have been created to power space probes (for example, the Cassini probe), some lighthouses in the former Soviet Union, and some pacemakers. The heat output of these generators diminishes with time; the heat is converted to electricity utilising the thermoelectric effect.

Core of a small nuclear reactor used for research. ... A schematic nuclear fission chain reaction. ... A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ... This article or section should include material from Fissile material In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. ... A nuclear power station. ... A generation II reactor is a nuclear power reactor of one of several types developed from the first generation I reactors. ... A generation III reactor is a development of any of the generation II nuclear reactor designs incorporating evolutionary improvements in design which have been developed during the lifetime of the generation II reactor designs, such as improved fuel technology, passive safety systems and standardised design. ... Pressurized water reactors (PWRs) (also VVER if of Russian design) are generation II nuclear power reactors that use ordinary water under high pressure as coolant and neutron moderator. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Clinton Power Station and is 5,000-acre cooling reservoir are located on a 14000-acre site near Clinton, Illinois, USA. Clintons final construction cost exceeded $4 billion, leading the plant to produce some of the most expensive power in the Midwest. ... Pressurized water reactors (PWRs) (also VVER if of Russian design) are generation II nuclear power reactors that use ordinary water under high pressure as coolant and neutron moderator. ... Three Mile Island redirects here. ... For details on this station, see Three Mile Island Nuclear Generating Station. ... This article does not cite its references or sources. ... Advanced Pressurized Water Reactor is a type of nuclear reactor which is an improved version of existing Pressurized Water Reactor types. ... The European Pressurized Reactor (EPR or US-EPR for the United States specific design) is a third generation nuclear fission pressurized water reactor (PWR) design. ... United States Naval reactors are given three-character designations consisting of a letter representing the ship type the reactor is designed for, a consecutive generation number, and a letter indicating the reactors designer. ... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution‎ (1,024 × 768 pixels, file size: 289 KB, MIME type: image/jpeg) I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free... Image File history File links Size of this preview: 800 × 600 pixelsFull resolution‎ (1,024 × 768 pixels, file size: 289 KB, MIME type: image/jpeg) I, the creator of this work, hereby grant the permission to copy, distribute and/or modify this document under the terms of the GNU Free... Laguna Verde is a Mexican nuclear power plant, located in the municipality of Alto Lucero, Veracruz. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... The Advanced Boiling Water Reactor (ABWR) is an improved design of boiling water reactor. ... The Economic Simplified Boiling Water Reactor (ESBWR) is a passively safe generation III+ reactor which builds on the success of the ABWR. Both are designs by General Electric, and are based on their BWR design. ... A pressurised heavy water reactor is a nuclear power reactor that uses unenriched natural uranium as its fuel and heavy water as a moderator (deuterium oxide D2O). ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... The Qinshan Nuclear Power Plant is a multi-unit nuclear plant in China. ... The CANDU reactor is a pressurized-heavy water, natural-uranium power reactor designed in the 1960s by a partnership between Atomic Energy of Canada Limited and the Hydro-Electric Power Commission of Ontario as well as several private industry participants. ... Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ... This article is about the chemical element. ... The Smiling Buddha was the first nuclear test explosion by India on May 18, 1974 at Pokhran. ... Image File history File links Metadata No higher resolution available. ... Image File history File links Metadata No higher resolution available. ... Ignalina Nuclear Power Plant is a two-unit RBMK-1500 nuclear power station in Visaginas, Lithuania. ... RBMK is an acronym for the Russian reaktor bolshoy moshchnosti kanalniy (Russian: Реактор Большой Мощности Канальный) which means reactor (of) high power (of the) channel (type), and describes a now obsolete class of graphite-moderated nuclear power reactor which was built only in the Soviet Union. ... For other uses, see Graphite (disambiguation). ... A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. ... The nuclear power plant at Chernobyl prior to the completion of the sarcophagus. ... Image File history File links Metadata Size of this preview: 800 × 498 pixelsFull resolution (1600 × 996 pixel, file size: 574 KB, MIME type: image/jpeg) Torness Nuclear Power Station. ... Image File history File links Metadata Size of this preview: 800 × 498 pixelsFull resolution (1600 × 996 pixel, file size: 574 KB, MIME type: image/jpeg) Torness Nuclear Power Station. ... Torness nuclear power station was the last of the United Kingdoms second generation nuclear power plants to be commissioned. ... An advanced gas-cooled reactor (AGR) is a type of nuclear reactor. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Schematic diagram of a Magnox nuclear reactor showing gas flow. ... A breeder reactor is a nuclear reactor that breeds fuel. ... The fast breeder or fast breeder reactor (FBR) is a fast neutron reactor designed to breed fuel by producing more fissile material than it consumes. ... Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution‎ (2,784 × 1,856 pixels, file size: 2. ... Image File history File links Metadata Size of this preview: 800 × 533 pixelsFull resolution‎ (2,784 × 1,856 pixels, file size: 2. ... Superphoenix (French: Superphénix or SPX) is a nuclear power station on the Rhône River at Creys-Malville in France, close to the border with Switzerland. ... Superphoenix (French: Superphénix or SPX) is a nuclear power station on the Rhône River at Creys-Malville in France, close to the border with Switzerland. ... Named for the first physicist to create a nuclear reactor, the Enrico Fermi plant is located between Detroit, Michigan and Toledo, Ohio in northeastern Monroe County, Michigan The 94MWe prototype fast breeder reactor Fermi 1 unit operated at the site from 1963 to 1972 and is now in the process... This article is about the fast breeder reactor in Japan. ... For sodium in the diet, see Edible salt. ... A fast neutron is a free neutron with a kinetic energy level close to 1 MeV (10 TJ/kg, hence a speed of 14,000 km/s. ... The Lead-cooled Fast Reactor is a Generation IV reactor that features a fast-spectrum lead or lead/bismuth eutectic liquid metal-cooled reactor with a closed fuel cycle. ... This article is about the metal. ... Lead Bismuth Eutectic or LBE is an eutectic alloy of lead and bismuth used as a coolant in some nuclear reactors, and is a proposed coolant for the lead cooled fast reactor, part of the Generation IV reactor initiative. ... The Sodium-cooled fast reactor is a sodium cooled reactor that uses fast neutrons. ... Supercritical water reactor scheme. ... Aqueous homogeneous reactors (AHR) are a type of nuclear reactor in which soluble nuclear salts (usually uranium sulfate or uranium nitrate) have been dissolved in water. ... // A radioisotope thermoelectric generator (RTG) is a simple electrical generator which obtains its power from radioactive decay. ... Radioactive decay is the process in which an unstable atomic nucleus loses energy by emitting radiation in the form of particles or electromagnetic waves. ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... Eddystone Lighthouse, one of the first wavewashed lighthouses For other uses, see Lighthouse (disambiguation). ... The Peltier–Seebeck effect, or thermoelectric effect, is the direct conversion of heat differentials to electric voltage and vice versa. ...

Advanced reactors

More than a dozen advanced reactor designs are in various stages of development.[3]Some are evolutionary from the PWR, BWR and PHWR designs above, some are more radical departures. The former include the Advanced Boiling Water Reactor (ABWR), two of which are now operating with others are under construction, and the planned passively safe ESBWR and AP1000 units (see Nuclear Power 2010 Program). Pressurized water reactors (PWRs) (also VVER if of Russian design) are generation II nuclear power reactors that use ordinary water under high pressure as coolant and neutron moderator. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... A pressurised heavy water reactor is a nuclear power reactor that uses unenriched natural uranium as its fuel and heavy water as a moderator (deuterium oxide D2O). ... The Advanced Boiling Water Reactor (ABWR) is an improved design of boiling water reactor. ... Passively safe is a form of nuclear reactor which uses the laws of physics to keep the nuclear reaction under control rather than engineered safety systems. ... The Economic Simplified Boiling Water Reactor (ESBWR) is a generation III+ reactor which builds on the success of the ABWR. Both are designs by General Electric, and are based on their BWR design. ... The AP1000 is a proposed passively safe pressurized water reactor designed and manufactured by Westinghouse Electric Company for nuclear power plants. ... The Nuclear Power 2010 Program was unveiled by the U.S. Secretary of the Department of Energy on February 14, 2002 as one means towards addressing the expected need for new power plants. ...

  • The Integral Fast Reactor was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces only a fraction of the waste of current reactors.[4]
  • The Pebble Bed Reactor, a High Temperature Gas Cooled Reactor (HTGCR), is designed so high temperatures reduce power output by doppler broadening of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium, which cannot have steam explosions, and which does not easily absorb neutrons and become radioactive, or dissolve contaminants that can become radioactive. Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that might aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.
  • SSTAR, Small, Sealed, Transportable, Autonomous Reactor is being primarily researched and developed in the US, intended as a fast breeder reactor that is passively safe and could be remotely shut down in case the suspicion arises that it is being tampered with.
  • The Clean And Environmentally Safe Advanced Reactor (CAESAR) is a nuclear reactor concept that uses steam as a moderator - this design is still in development.
  • Subcritical reactors are designed to be safer and more stable, but pose a number of engineering and economic difficulties. One example is the Energy amplifier.
  • Thorium based reactors. It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, Thorium, which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.
    • Advanced Heavy Water Reactor — A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the Bhabha Atomic Research Centre (BARC).
    • KAMINI — A unique reactor using Uranium-233 isotope for fuel. Built by BARC and IGCAR Uses thorium.
    • India is also building a bigger scale FBTR or fast breeder thorium reactor to harness the power with the use of thorium.

The Integral Fast Reactor or Advanced Liquid-Metal Reactor is a design for a nuclear fast reactor with a specialized nuclear fuel cycle. ... Graphite Pebble for Reactor The pebble bed reactor (PBR) or pebble bed modular reactor (PBMR) is an advanced nuclear reactor design. ... The High Temperature Gas-cooled Reactor or HTGR is a gas cooled reacter that is fueled with a mixture of graphite and spherical fuel particles. ... Doppler broadening is a broadening of spectral lines due to thermal agitation. ... A possible design for SSTAR. SSTAR is an acronym for the small, sealed, transportable, autonomous reactor - being primarily researched and developed in the US by Lawrence Livermore National Laboratory. ... The Clean And Environmentally Safe Advanced Reactor (CAESAR) is a nuclear reactor concept that uses steam as a moderator. ... A subcritical reactor is a nuclear fission reactor that produces fission without achieving criticality. ... In nuclear physics, an energy amplifier is a novel type of nuclear power reactor, a subcritical reactor, in which an energetic particle beam is used to stimulate a reaction, which in turn releases enough energy to power the particle accelerator and leave an energy profit for power generation. ... The Advanced Heavy Water Reactor (AHWR) is a proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. ... The Bhabha Atomic Research Centre (BARC) is Indias primary nuclear research facility. ... KAMINI (Kalpakkam Mini reactor) is a Uranium-233 fueled, low power (30 kW) research reactor designed and built jointly by the Bhabha Atomic Research Centre (BARC) and Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam. ... The Bhabha Atomic Research Centre (BARC) is Indias primary nuclear research facility. ... The Reactor Research Centre set up at Kalpakkam, India, 80kms south of Chennai in 1971 under the Department of Atomic Energy (DAE) was renamed Indira Gandhi Center for Atomic Research (IGCAR) in 1985. ...

Generation IV reactors

Generation IV reactors are a set of theoretical nuclear reactor designs currently being researched. These designs are generally not expected to be available for commercial construction before 2030. Current reactors in operation around the world are generally considered second- or third-generation systems, with the first-generation systems having been retired some time ago. Research into these reactor types was officially started by the Generation IV International Forum (GIF) based on eight technology goals. The primary goals being to improve nuclear safety, improve proliferation resistance, minimize waste and natural resource utilization, and to decrease the cost to build and run such plants.[5] Generation IV reactors (Gen IV) are a set of theoretical nuclear reactor designs currently being researched. ...

The Supercritical Water-cooled Reactor combines higher efficiency than a GCR with the safety of a PWR, though it is perhaps more technically challenging than either. The water is pressurized and heated past its critical point, until there is no difference between the liquid and gas states. An SCWR is similar to a BWR, except there is no boiling (as the water is critical), and the thermal efficiency is higher as the water behaves more like a classical gas. This is an epithermal neutron reactor design.

The Gas-Cooled Fast Reactor (GFR) system is a Generation IV reactor that features a fast-neutron spectrum and closed fuel cycle for efficient conversion of fertile uranium and management of actinides. ... The Lead-cooled Fast Reactor is a Generation IV reactor that features a fast-spectrum lead or lead/bismuth eutectic liquid metal-cooled reactor with a closed fuel cycle. ... Molten salt reactor scheme. ... The Sodium-cooled fast reactor is a sodium cooled reactor that uses fast neutrons. ... Supercritical water reactor scheme. ... In chemistry and condensed matter physics, a critical point specifies the conditions (temperature, pressure) at which the liquid state of the matter ceases to exist. ... Very high temperature reactor scheme. ...

Generation V+ reactors

Designs which are theoretically possible, but which are not being actively considered or researched at present. Though such reactors could be built with current or near term technology, they trigger little interest for reasons of economics, practicality, or safety.

  • Liquid Core reactor. A closed loop liquid core nuclear reactor, where the fissile material is molten uranium cooled by a working gas pumped in through holes in the base of the containment vessel.
  • Gas core reactor. A closed loop version of the nuclear lightbulb rocket, where the fissile material is gaseous uranium-hexafluoride contained in a fused silica vessel. A working gas (such as hydrogen) would flow around this vessel and absorb the UV light produced by the reaction. In theory, using UF6 as a working fuel directly (rather than as a stage to one, as is done now) would mean lower processing costs, and very small reactors. In practice, running a reactor at such high power densities would probably produce unmanageable neutron flux.
  • Gas core EM reactor. As in the Gas Core reactor, but with photovoltaic arrays converting the UV light directly to electricity.
  • Fission fragment reactor

Sketch of nuclear thermal rocket In a nuclear thermal rocket a working fluid, usually hydrogen, is heated in a high temperature nuclear reactor, and then expands through a rocket nozzle to create thrust. ... A nuclear lightbulb is a specific type of gas core nuclear reactor that is operated at such high temperature (aprox. ... Similar to how the fission-fragment rocket produces thrust, a fission fragment reactor is a nuclear reactor that generates electricity by decelerating an ion beam of fission byproducts instead of using nuclear reactions to generate heat. ...

Fusion reactors

Controlled nuclear fusion could in principle be used in fusion power plants to produce power without the complexities of handling actinides, but significant scientific and technical obstacles remain. Several fusion reactors have been built, but as yet none has 'produced' more thermal energy than electrical energy consumed. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050. The ITER project is currently leading the effort to commercialize fusion power. The deuterium-tritium (D-T) fusion reaction is considered the most promising for producing fusion power. ... Internal view of the JET tokamak superimposed with an image of a plasma taken with a visible spectrum video camera. ... The actinide series encompasses the 14 chemical elements that lie between actinium and nobelium on the periodic table with atomic numbers 89 - 102 inclusive. ... ITER is an international tokamak (magnetic confinement fusion) research/engineering project designed to prove the scientific and technological feasibility of a full-scale fusion power reactor. ...


Nuclear fuel cycle

Main article: Nuclear fuel cycle

Thermal reactors generally depend on refined and enriched uranium. Some nuclear reactors can operate with a mixture of plutonium and uranium (see MOX). The process by which uranium ore is mined, processed, enriched, used, possibly reprocessed and disposed of is known as the nuclear fuel cycle. The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. ... These pie-graphs showing the relative proportions of uranium-238 (blue) and uranium-235 (red) at different levels of enrichment. ... The Mox are a alien race that inhabit Planet X, they are divided into clans which seem to be forever at war. ... // Nuclear reprocessing separates any usable elements (e. ... The nuclear fuel cycle, also called nuclear fuel chain, is the progression of nuclear fuel through a series of differing stages. ...


Under 1% of the uranium found in nature is the easily fissionable U-235 isotope and as a result most reactor designs require enriched fuel. Enrichment involves increasing the percentage of U-235 and is usually done by means of gaseous diffusion or gas centrifuge. The enriched result is then converted into uranium dioxide powder, which is pressed and fired onto pellet form. These pellets are stacked into tubes which are then sealed and called fuel rods. Many of these fuel rods are used in each nuclear reactor. For other uses, see Isotope (disambiguation). ... -1... A cascade of gas centrifuges at a United States enrichment plant. ... UO2 A black, radioactive, crystalline powder, once used in the late 1800s to mid-1900s in ceramic glazes. ... Nuclear Fuel Process A graph comparing nucleon number against binding energy Nuclear fuel is any material that can be consumed to derive nuclear energy, by analogy to chemical fuel that is burned to derive energy. ...


Most BWR and PWR commercial reactors use uranium enriched to about 4% U-235, and some commercial reactors with a high neutron economy do not require the fuel to be enriched at all (that is, they can use natural uranium). According to the International Atomic Energy Agency there are at least 100 research reactors in the world which use highly enriched, weapons-grade uranium (90% enrichment) as their fuel. Because of the risk of theft of this fuel, which could be potentially turned into a nuclear weapon without unsurmountable difficulty, for many years there have been many campaigns to attempt to convert reactors of this type to run on low -enriched uranium which poses less of a direct proliferation threat.[6] Neutron economy is defined as the ratio of an adjoint weighted average of the excess neutron production divided by an adjoint weighted average of the fission production. ... The International Atomic Energy Agency (IAEA) seeks to promote the peaceful use of nuclear energy and to inhibit its use for military purposes. ... Research reactors comprise a wide range of civil and commercial nuclear reactors which are generally not used for power generation. ...


It should be noted that fissionable U-235 and non-fissionable U-238 are both used in the fission process. U-235 is fissionable by thermal (i.e. slow-moving) neutrons. A thermal neutron is one which is moving about the same speed as the atoms around it. Since all atoms vibrate proportionally to their absolute temperature, a thermal neutron has the best opportunity to fission U-235 when it is moving at this same vibrational speed. On the other hand, U-238 is more likely to capture a neutron when the neutron is moving very fast. This U-239 atom will soon decay into plutonium-239, which is another fuel. Pu-239 is a viable fuel and must be accounted for even when a highly enriched uranium fuel is used. Plutonium fissions will dominate the U-235 fissions in some reactors, especially after the initial loading of U-235 is spent. Plutonium is fissionable with both fast and thermal neutrons, which make it ideal for either nuclear reactors or nuclear bombs. For other uses, see Temperature (disambiguation). ...


Most reactor designs in existence are thermal reactors and typically use water as a neutron moderator (moderator means that it slows down the neutron to a thermal speed) and as a coolant. But in a fast breeder reactor, some other kind of coolant is used which will not moderate or slow the neutrons down much. This enables fast neutrons to dominate, which can effectively be used to constantly replenish the fuel supply. By merely placing cheap unenriched uranium into such a core, the non-fissionable U-238 will be turned into Pu-239, "breeding" fuel. The fast breeder or fast breeder reactor (FBR) is a fast neutron reactor designed to breed fuel by producing more fissile material than it consumes. ...


Fueling of nuclear reactors

The amount of energy in the reservoir of nuclear fuel is frequently expressed in terms of "full-power days," which is the number of 24-hour periods (days) a reactor is scheduled for operation at full power output for the generation of heat energy. The number of full-power days in a reactor's operating cycle (between refueling outage times) is related to the amount of fissile uranium-235 (U-235) contained in the fuel assemblies at the beginning of the cycle. A higher percentage of U-235 in the core at the beginning of a cycle will permit the reactor to be run for a greater number of full-power days. Nuclear Fuel Process A graph comparing nucleon number against binding energy Nuclear fuel is any material that can be consumed to derive nuclear energy, by analogy to chemical fuel that is burned to derive energy. ... This article or section should include material from Fissile material In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ...


At the end of the operating cycle, the fuel in some of the assemblies is "spent," and is discharged and replaced with new (fresh) fuel assemblies. Although in practice, it is the buildup of reaction poisons in nuclear fuel that determines the lifetime of nuclear fuel in a reactor; long before all possible fissions have taken place, the buildup of long-lived neutron absorbing fission products damps out the chain reaction. The fraction of the reactor's fuel core replaced during refueling is typically one-fourth for a boiling-water reactor and one-third for a pressurized-water reactor. For information on radioactive toxins see Radiation poisoning A nuclear poison is a substances with a large neutron absorption cross-section in applications, such as nuclear reactors, when absorbing neutrons is an undesirable effect. ...


Not all reactors need to be shut down for refueling; for example, pebble bed reactors, RBMK reactors, molten salt reactors, Magnox, AGR and CANDU reactors allow fuel to be shifted through the reactor while it is running. In a CANDU reactor, this also allows individual fuel elements to be moved about within the reactor core to places that are best suited to the amount of U-235 in the fuel element. Graphite Pebble for Reactor The pebble bed reactor (PBR) or pebble bed modular reactor (PBMR) is an advanced nuclear reactor design. ... RBMK is an acronym for the Russian reaktor bolshoy moshchnosti kanalniy (Russian: Реактор Большой Мощности Канальный) which means reactor (of) high power (of the) channel (type), and describes a now obsolete class of graphite-moderated nuclear power reactor which was built only in the Soviet Union. ... Molten salt reactor scheme. ... Schematic diagram of a Magnox nuclear reactor showing gas flow. ... Schematic diagram of the Advanced Gas-cooled Reactor. ... The CANDU reactor is a pressurized-heavy water, natural-uranium power reactor designed in the 1960s by a partnership between Atomic Energy of Canada Limited and the Hydro-Electric Power Commission of Ontario as well as several private industry participants. ...


The amount of energy extracted from nuclear fuel is called its "burn up," which is expressed in terms of the heat energy produced per initial unit of fuel weight. Burn up is commonly expressed as megawatt days thermal per metric ton of initial heavy metal.


Safety

Main article: Nuclear safety
See also: Nuclear safety in the U.S.

This diagram demonstrates the defense in depth quality of nuclear power plants. ... This article or section does not cite its references or sources. ...

Natural nuclear reactors

Although nuclear reactors are often thought of as being solely a product of modern technology, the first nuclear reactors were in fact naturally occurring. A natural nuclear fission reactor can occur under certain circumstances that mimic the conditions in a constructed reactor.[7] Fifteen natural fission reactors have so far been found in three separate ore deposits at the Oklo mine in Gabon, West Africa. First discovered in 1972 by French physicist Francis Perrin, they are collectively known as the Oklo Fossil Reactors. These reactors ran for approximately 150 million years, averaging 100 kW of power output during that time. The concept of a natural nuclear reactor was theorized as early as 1956 by Paul Kuroda at the University of Arkansas[8][9] Natural Reactors refer to a handful of Uranium deposits that have been discovered, mostly in Oklo, Gabon. ... Natural Reactors refer to a handful of Uranium deposits that have been discovered, mostly in Oklo, Gabon. ... Oklo is a place in the West African state of Gabon. ...  Western Africa (UN subregion)  Maghreb[1] West Africa or Western Africa is the westernmost region of the African continent. ... Francis Perrin (Paris, 1901 - id. ... Natural Reactors refer to a handful of Uranium deposits that have been discovered, mostly in Oklo, Gabon. ... The University of Arkansas is a public co-educational land-grant university. ...


Such reactors can no longer form on Earth: radioactive decay over this immense time span has reduced the proportion of U-235 in naturally occurring uranium to below the amount required to sustain a chain reaction.


The natural nuclear reactors formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, and a strong chain reaction took place. The water moderator would boil away as the reaction increased, slowing it back down again and preventing a meltdown. The fission reaction was sustained for hundreds of thousands of years.


These natural reactors are extensively studied by scientists interested in geologic radioactive waste disposal. They offer a case study of how radioactive isotopes migrate through the earth's crust. This is a significant area of controversy as opponents of geologic waste disposal fear that isotopes from stored waste could end up in water supplies or be carried into the environment.


See also

Energy Portal
Nuclear technology Portal

Image File history File links Portal. ... Image File history File links Portal. ... Auxiliary feedwater is a backup water supply used during nuclear plant startup and shutdown to supply water to the steam generators during accident conditions for removing decay heat from the reactor. ... A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. ... David Hahn (born October 1976) attempted to build a nuclear breeder reactor in 1994 in his backyard shed in Clinton Township, Michigan, a suburb of Detroit, at the age of 17. ... Higher electricity use per capita correlates with a higher score on the Human Development Index(1997). ... List of nuclear reactors is a comprehensive annotated list of all the nuclear reactors of the world, sorted by country. ... List of United States Naval reactors is a comprehensive annotated list of all naval reactors designed, built, or used by the United States Navy. ... This article does not adequately cite its references or sources. ... Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... A nuclear power station at Cattenom in France. ... The Nuclear Reactor Operator Badge is a decoration of the United States Army which was issued between the years of 1965 and 1990. ... Most nuclear reactors use a chain reaction to induce a controlled rate of nuclear fission in fissile material, releasing both energy and free neutrons. ... A SCRAM is an emergency shutdown of a nuclear reactor - though the term has been extended to cover shutdowns of other complex operations, such as server farms and even large model railroads (see Tech Model Railroad Club). ... Safety engineering is an applied science strongly related to systems engineering and the subset System Safety Engineering. ... Technology assessment (TA, German Technikfolgenabschätzung) is the study and evaluation of new technologies. ...

References

  1. ^ A Technology Roadmap for Generation IV Neuclear Energy SystemsPDF (4.33 MiB); see "Fuel Cycles and Sustainability"
  2. ^ World Nuclear Association Information Brief -Research Reactors
  3. ^ Advanced Nuclear Power Reactors. Uranium Information Centre. Retrieved on June 28, 2006.
  4. ^ Dr. Charles Till. Nuclear Reaction: Why Do Americans Fear Nuclear Power?. Public Broadcasting Service (PBS). Retrieved on 2006-11-09.
  5. ^ Generation IV Nuclear Reactors. Uranium Information Centre. Retrieved on June 28, 2006.
  6. ^ IAEA, Improving Security at World's Nuclear Research Reactors: Technical and Other Issues Focus of June Symposium in Norway (7 June 2006).
  7. ^ Video of physics lecture - at Google Video; a natural nuclear reactor is mentioned at 42:40 mins into the video
  8. ^ Oklo: Natural Nuclear Reactors. Office of Civilian Radioactive Waste Management. Retrieved on June 28, 2006.
  9. ^ Oklo's Natural Fission Reactors. American Nuclear Society. Retrieved on June 28, 2006.

“PDF” redirects here. ... MiB redirects here. ... The Uranium Information Centre is an Australian website established by companies involved in uranium mining. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 313th day of the year (314th in leap years) in the Gregorian calendar. ... The Uranium Information Centre is an Australian website established by companies involved in uranium mining. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... The American Nuclear Society is a non-profit, educational organization established by a group of individuals who recognized the need to bring together professional activities within the fields of nuclear science and technology. ... is the 179th day of the year (180th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

External links

  • Boiling Water Reactor Plant Technology Education - Includes the PC-based BWR reactor simulation.
  • World Nuclear Fuel Facilities
  • How Nuclear Power Works - Howstuffworks.com
  • The Pebble Bed Modular Reactor - Whyfiles.org - On a bed of pebbles
  • World Nuclear Association - How it Works
  • A Debate: Is Nuclear Power The Solution to Global Warming?
  • Union of Concerned Scientists, Concerns re: US nuclear reactor program
  • The Canadian Nuclear FAQ - a very information-rich resource about Canadian CANDU reactors.
  • Annotated bibliography on Nuclear Reactors from the Alsos Digital Library for Nuclear Issues
  • Fixed Bed Nuclear Reactor
  • Freeview Video 'Nuclear Power Plants - What's the Problem' A Royal Institution Lecture by John Collier by the Vega Science Trust.
  • U.S. plants and operators
  • SCK.CEN Belgian Nuclear Research Centre in Mol.
  • Glossary of Nuclear Terms
  • An Interactive VR Panorama of the cooling towers at Temelin Nuclear Power Plant, Czech Republic
  • Nuclear Energy Institute – How it Works: Electric Power Generation

 
 

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