Nuclear reactor technology | Wikipedia audio article
A, nuclear. Reactor formerly. Known as an atomic pile is a device, used to initiate, and control a, self-sustained. Nuclear, chain reaction. Nuclear. Reactors. Are used at nuclear, power plants. For electricity. Generation, and in propulsion. Of ships. Heat. From nuclear fission. Is passed to a working, fluid water, or gas which, in turn runs through steam turbines. These. Either drive a ship's, propellers. Or turn electrical. Generators. Shafts. Nuclear. Generated. Steam in principle. Can be used for industrial process. Heat or for district, heating. Some. Reactors, are used to produce isotopes. For medical, and industrial use or for production. Of weapons-grade, plutonium. Some. Are run only for research as of. Early 2019, the, IAEA, reports. There are, 454. Nuclear. Power reactors. In. 226. Nuclear. Research reactors. In operation around, the world. Topic. Mechanism. Just. As conventional. Power stations. Generate, electricity, by, harnessing the thermal, energy released. From burning fossil fuels, nuclear. Reactors convert, the energy released by controlled. Nuclear fission into. Thermal energy for further conversion, to mechanical. Or electrical, forms. Topic. Fishin. When, a large fissile, atomic, nucleus, such as uranium. 235. Or plutonium. 239. Absorbs. A neutron it. May undergo nuclear. Fission, the. Heavy nucleus, splits into two or more lighter, nuclei. The fission, products, releasing. Kinetic, energy, gamma radiation. And free, neutrons, a, portion. Of these neutrons. May later be absorbed, by other fissile, atoms, and trigger further fission, events, which release more neutrons, and sir on this. Is known as a nuclear, chain reaction. To. Control, such a nuclear, chain reaction. Neutron poisons, and neutron moderators. Can change, the portion, of neutrons, that will go on to cause more fission. Nuclear. Reactors. Generally, have automatic. And manual systems. To shut the fission reaction down if monitoring, detects, unsafe, conditions, commonly. Used moderators. Include, regular, light water in seventy, four point eight percent, of the world's, reactors, solid. Graphite. 20%. Of reactors, and heavy water five percent, of reactors. Some. Experimental, types. Of reactor, have used beryllium, and hydrocarbons. Have been suggested. As another possibility. Topic. Heat, generation. The, reactor, core generates. Heat in a number of ways. The. Kinetic, energy of fission products, is converted, to thermal energy when, these nuclei, collide with, nearby atoms. The. Reactor, absorbed, some of the gamma rays produced, during fission, and converts, their energy into heat. Heat. Is produced by the radioactive, decay. Of fission, products, and materials, that have been activated. By Neutron, absorption. This. Decay, heat source will remain for some time even after the reactor, is shut down a kilogram, of uranium. 235. U-235. Converted. Via nuclear, processes, releases. Approximately. Three million times more energy than a kilogram, of cold burn conventionally. 7.2. Times one thousand, and thirteen, joules per kilogram, of uranium.
235. Versus, 2.4 times. 107. Joules per kilogram of coal. Topic. Cooling. A nuclear. Reactor coolant. Usually. Water but, sometimes a gas or a liquid metal, like, liquid, sodium or molten salt, is. Circulated. Past the reactor core to absorb, the heat that it generates. The. Heat is carried away from the reactor, and is then used to generate steam. Most. Reactor, systems, employ, a cooling, system that is physically, separated. From the water that will be boiled to produce pressurized. Steam, for the turbines, like, the pressurized, water reactor. However. In some, reactors, the water for the steam turbines. Is boiled directly, by the reactor, core for example, the boiling, water reactor. Topic. Reactivity. Control. The, rate of fission reactions. Within a reactor, core can be adjusted, by controlling. The quantity of neutrons. That are able to induce further fish and events. Nuclear. Reactors typically, employ several, methods, of Neutron, control, to adjust the reactors, power output. Some. Of these methods arising, naturally, from the physics, of radioactive. Decay and, are simply accounted, for during the reactors, operation. While others are mechanisms, engineered, into the reactor, design for a distinct, purpose. The. Fastest, method for adjusting, levels of fish and inducing, neutrons, in a reactor, is via movement, of the control, rods. Control. Rods are made of neutron, poisons. And therefore, tend to absorb neutrons. When. A control, rod is inserted. Deeper, into the reactor, it absorbs, more neutrons, than the material, it displaces. Often. The moderator. This. Action, results, in fewer neutrons, available, to cause fission, and reduces, the reactors, power output. Conversely. Extracting. The control, rod will result, in an increase in the rate of fission events, and an increase, in power. The. Physics, of radioactive. Decay also, affects Neutron, populations. In a reactor. One. Such process, is delayed Neutron. Emission, by a number of Neutron, rich fish and isotopes. These. Delayed, neutrons, account, for about. 0.65. Percent. Of the total neutrons. Produced in fission with the remainder termed, prompt. Neutrons. Released, immediately. Upon. Fission, the fission, products, which produce delayed, neutrons, have half-lives, for the decay by Neutron, emission, that range from milliseconds. To as long as several minutes and so considerable.
Time Is required to determine exactly, when a reactor, reaches, the critical point. Keeping. The reactor in the zone of chain, reactivity. Where delayed neutrons, are necessary, to achieve a critical, mass state allows, mechanical. Devices or, human, operators, to control it, chain-reaction in real-time. Otherwise. The time between achievement. Of criticality, and, nuclear, meltdown, as a result, of an exponential, power, surge, from the normal nuclear chain, reaction. Would be too short to allow for intervention. This. Last stage, where, delayed neutrons, are no longer required to maintain criticality. Is known, as the prompt, critical point, there. Is a scale for describing, criticality. In numerical, form in which bare criticality, is known as $0 and the prompt, critical point, is $1.00 and other points, in the process interpolated. In cents. In. Some, reactors, the coolant also acts as a neutron, moderator a. Moderator. Increases. The power of the reactor, by causing, the fast neutrons, that are released from fission to lose energy and become thermal. Neutrons. Thermal. Neutrons, are more likely than, fast neutrons. To cause fission, if the, coolant is a moderator, then temperature. Changes, can affect the density of the coolant moderator, and therefore, change power output, a higher. Temperature, coolant, would be less dense and therefore, a less effective moderator. In. Other reactors. The coolant acts as a Poisson by absorbing, neutrons, in the same way that the control, rods do, in. These reactors power, output, can be increased, by heating the coolant, which makes it a less dense poison. Nuclear. Reactors, generally, have automatic. And manual systems. To scram the reactor, in an emergency, shutdown. These. Systems, insert, large amounts, of poison, often boron, in the form of boric, acid into, the reactor, to shut the fission, reaction down if unsafe, conditions, are detected, or anticipated. Most types of reactors, are sensitive, to a process, variously. Known as xenon poisoning. Or the iodine, pit, the. Common, fission, product, xenon, 135. Produced. In the fission process acts, as a neutron, poison, that absorbs, neutrons, and therefore, tends to shut the reactor down. Xenon-135. Accumulation. Can be controlled, by keeping, power levels, high enough to destroy, it by Neutron, absorption, as fast as it is produced. Fish. And also produces. Iodine. 135. Which in turn decays, with a half-life of. 6.5. Seven hours to new xenon, 135. When. The reactor, is shut down iodine. 135. Continues. To decay to xenon, 135. Making. Restarting. The reactor, more difficult, for a day or two as the xenon, 135. Decays. Into cesium. 135. Which is not nearly as poisonous. As xenon 135. With, a half-life, of 9.2. Hours. This. Temporary, state is the iodine. Pit if the. Reactor, has sufficient, extra, reactivity. Capacity. It can be restarted, as the. Extra, xenon 135. Is. Transmuted, to xenon. 136. Which is much less a neutron, poison, within a few hours the reactor, experiences. A xenon. Burn, off power, transient. Control. Rods must be further inserted. To replace the Neutron absorption, of the lost xenon, 135. Failure. To properly follow such a procedure, was a key step in the Chernobyl, disaster, reactors.
Used In nuclear, marine propulsion. Especially. Nuclear submarines. Often, cannot be run at continuous, power around the clock in the same way that land-based, power reactors. Are normally, run and in addition, often need to have a very long core life without refueling, for this. Reason, many designs, use highly, enriched uranium but. Incorporate. Burnable, Neutron, poison, in the fuel rods. This. Allows the reactor, to be constructed. With an excess of fissionable. Material, which is nevertheless made, relatively, safe early, in the reactors, fuel burn cycle, by the presence, of the neutron, sobbing, material. Which is later replaced by normally, produced, long-lived, neutron, poisons, far, longer lived than xenon-135. Which gradually accumulate. Over the fuel loads operating. Life. Topic. Electrical. Power generation. The, energy, released in efficient, process, generates, heat some of which can be converted into, usable, energy a common. Method of harnessing, this thermal, energy is to use it to boil water to produce pressurized. Steam, which will then drive a steam, turbine, that turns an alternator, and generates. Electricity. Topic. Early, reactors. The, neutron, was discovered. In 1932. By, British, physicist, James Chadwick. The. Concept, of a nuclear, chain reaction. Brought about by nuclear, reactions, mediated. By neutrons, was first realised, shortly, thereafter by, Hungarian. Scientist. Leo Szilard, in 1933. He. Filed a patent, for his idea, of a simple, reactor, the following, year while working at the Admiralty. In London. However. Szilard's. Idea, did not incorporate the, idea of nuclear fission, as a neutron, source since, that process, was not yet discovered. Psyllids. Ideas, for nuclear, reactors, using neutron, mediated. Nuclear, chain reactions. In light element proved unworkable. Inspiration. For a new type of reactor. Using, uranium came. From the discovery, by Lise Meitner Fritz, Strassmann and, Otto Hahn, in, 1938. That bombardment. Of uranium. With neutrons, provided. By an alpha on beryllium, fusion, reaction. Neutron. Howitzer. Produced. A barium, residue, which they reasoned, was created, by the fissioning. Of the uranium, nuclei. Subsequent. Studies in early 1939. One, of them by silard and Fermi, revealed, that several, neutrons, were also, released during the fissioning, making, available the opportunity. For the nuclear, chain reaction. That szilárd had envisioned, six years previously. On. The. 2nd of august 1939. Albert. Einstein, signed a letter to President, Franklin D Roosevelt written, by szilárd suggesting. That the discovery, of uranium, fission could lead to the development of, extremely. Powerful. Bombs of a new type. Giving. Impetus, to the study of reactors, and fission, szilárd. And einstein knew each other well and had worked together years, previously. But Einstein, had never thought about this possibility. For nuclear, energy until. Szilárd reported, it to him at the beginning of his quest to produce the einstein, Szilard letter to alert the US government. Shortly. After, Hitler's, Germany invaded, Poland in, 1939. Starting. World War two in Europe, the. US was not yet officially, at war but, in October when. The Einstein, silard letter was delivered to him Roosevelt, commented. That the purpose, of doing the research was to make sure the, Nazis, don't blow us up, the. US nuclear, project, followed, although with some delay as there remained, skepticism. Some of it from Fermi, and also, little action, from the small number, of officials, in the government who, were initially charged. With moving the project forward. The. Following, year the US government, received, the Frisch peels memorandum. From the UK, which stated, that the amount of uranium needed. For a chain reaction was, far lower than had previously been. Thought. The. Memorandum. Was a product of the Mord committee which, was working on the UK, atomic, bomb project known. As Jubilees. Later, to be subsumed, within the manhattan project. Eventually. The first artificial. Nuclear. Reactor, Chicago. Pile 1 was constructed. At the University. Of Chicago by, a team led by Italian. Physicist, Enrico Fermi, in, late, 1942. By. This time the program had, been pressured, for a year by us entry, into the war, the. Chicago. Pile achieved, criticality, on, the 2nd, of December, 1942. At, 3:25. P.m.. The. Reactor, support, structure, was made of wood which supported, a pile hence, the name of graphite, blocks embedded. In which was natural, uranium oxide.
Pseudo, Spheres or briquettes. Soon. After, the Chicago pile. The US military, developed, a number of nuclear, reactors, for the Manhattan Project starting. In 1943. The. Primary, purpose, for the largest reactors, located. At the Hanford Site in Washington. Was the mass production, of plutonium for. Nuclear weapons. Fermi. And szilárd applied, for a patent, on reactors, on the 19th, of December. 1944. Its. Issuance, was delayed, for 10 years because of wartime, secrecy. World's. First nuclear. Power plant, is the. Claim made by signs, at the site of the eBRI, which, is now a museum, near Arco, Idaho. Originally. Called. Chicago. Pile for, it. Was carried, out under the direction of, Walters, in for Argonne National Laboratory. This. Experimental. LM FBR operated. By the US Atomic, Energy Commission produced. 0.8. Kilowatts, in a test on the 20th, of December, 1951. And, 100. Kilowatts, electrical. The following, day having, a design output of 200, kilowatts, electrical. Besides. The military, uses, of nuclear reactors. There were political reasons, to pursue civilian, use of atomic, energy. U.s.. President, Dwight Eisenhower made. His famous Atoms, for Peace speech, to the UN General Assembly on, the 8th of December, 1953. This. Diplomacy. Led to the dissemination of, reactor, technology. To US institutions and, worldwide the, first nuclear, power plant, built for civil purposes was, the am-1 oblems, nuclear, power plant, launched, on the 27th. Of june, 1954. In the soviet union it. Produced, around 5 megawatts, electrical. After. World war ii, the US military, sought other uses, for nuclear, reactor, technology. Research. By the Army, in the Air Force never, came to fruition however, the US Navy, succeeded. When they steamed the USS, Nautilus, SSN. 571. On nuclear, power the 17th. Of January. 1955. The. First commercial. Nuclear power station. Called a halt in sellafield, England, was opened in, 1956. With an initial, capacity, of 50, megawatts, later, 200 megawatts. The first portable, nuclear. Actor, Alko, p.m., to a, used. To generate electrical. Power to, megawatts, for campus century from 1960. Topic. Reactor. Types. You. Topic. Classifications. Nuclear. Reactors are classified, by several, methods a, brief, outline, of these classification. Methods, is provided. Topic. Classification. By type of nuclear, reaction. Topic. Nuclear. Fission. All commercial, power, reactors. Are based on nuclear fission they. Generally, use uranium, and, its product, plutonium. Is nuclear, fuel though a thorium, fuel cycle is, also possible. Fission. Reactors, can be divided roughly, into two classes. Depending on the energy of the neutrons, that sustain, the fission chain reaction. Thermal. Reactors, the most common, type of nuclear. Reactor you, slowed, or thermal, neutrons, to keep up the fission of their fuel. Almost. All current, reactors are of this type these. Contain, neutron moderator materials. That slow neutrons, until, their Neutron temperature. Is thermalized. That, is until, their kinetic energy approaches, the average kinetic energy of the surrounding, particles. Thermal. Neutrons, have a far higher cross-section. Probability. Of visioning, the fissile, nuclei. Uranium-235. Plutonium. 239. And, plutonium. 241. And a relatively, lower probability of, neutron, capture by, uranium. 238. U. 238. Compared. To the faster, neutrons, that originally, result from fission allowing. The use of low enriched, uranium or, even natural uranium fuel. The. Moderator, is often also the coolant usually, water under, high pressure to increase the, boiling point. These. Are surrounded, by a reactor. Vessel, instrumentation. To monitor, and control the reactor, radiation. Shielding, and a containment, building. Fast-neutron. Reactors. Use fast neutrons. To cause fission, in their fuel, they. Do not have a neutron, moderator and. Use less moderating. Coolants. Maintaining. A chain reaction requires. The fuel to be more highly enriched, in fissile, material, about 20%. Or more due, to the relatively, lower probability, of fishin versus capture, by u, 238. Fast.
Reactors. Have the potential, to produce less, transfer, in each waste but cause all actinides, efficient, able with fast neutrons. But they are more difficult to build in more expensive to, operate over. All 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. Topic. Classification. By moderator, material. Used, by thermal, reactors. Graphite. Moderated, reactors. Water moderated. Reactors. Heavy. Water reactors. Used in Canada India, Argentina, China. Pakistan. Romania. And South Korea. Light. Water moderated. Reactors, l-w, ours light. Water reactors. The most common, type of thermal. Reactor, use ordinary, water to moderate, and cool the reactors. When. At operating, temperature if. The temperature of, the water increases, its, density, drops and fewer, neutrons, passing. Through it has slowed enough to trigger further reactions. That. Negative, feedback, stabilizes. The reaction, rate, graphite. And heavy water reactors. Tend to be more thoroughly thermalized. Than light water reactors. Due. To the extra, thermalization, these. Types can use natural uranium, unenriched. Fuel. Light. Element, moderated. Reactors. Molten. Salt reactors. MSRs. Are moderated, by light elements, such as lithium or beryllium which, are constituents, of the coolant fuel matrix, salts, LIF and beryllium fluoride. Liquid. Metal cooled reactors. Such, as those whose coolant, is a mixture, of lead and bismuth, may use beo, as a moderator. Organically. Moderated. Reactors om. Are used, by fennel and tur fennel is moderator, and coolant. Topic. Classification. By coolant. Water-cooled. Reactor. There are 104. Operating. Reactors, in the United, States, of. These, 69. Are pressurized, water reactors. PWR. And 35. Are boiling, water reactors. BWR. Pressurized. Water reactor. PWR. Pressurized. Water reactors.
Constitute. The large majority, of all Western nuclear. Power plants. A. Primary. Characteristic. Of PW. Ours is a pressurizer. A specialized. Pressure, vessel. Most. Commercial. PWRs. And naval reactors, use pressurizes. 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 are PV, 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. Pressurised. Heavy water, reactors. Are a subset, of pressurized. Water reactors. Sharing. The use of a pressurized, isolated. Heat transport, loop but using, heavy water is coolant, and moderator for. The greater Neutron, economies, it offers. Boiling. Water reactor. BWR. BW. ARS are characterized. By boiling, water around, the fuel rods in the lower portion, of a primary reactor, Pressure Vessel a. Boiling. Water reactor, uses. 235. U enriched, as uranium dioxide, as. Its fuel, the. Fuel is assembled, into rods housed in a steel vessel that is submerged, in water, the. Nuclear, fission, causes, the water to boil generating. Steam this. Steam flows through pipes into turbines. The. Turbines, are driven by the steam, and this process, generates, electricity. During. Normal operation. Pressure is controlled by 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. Liquid. Metal coolants, have included. Sodium, nak. Lead led bismuth, eutectic. And in early reactors, mercury. Sodium-cooled. Fast. Reactor. Lead. Cooled, fast, reactor. Gas. Cooled, reactors. Are cooled by a circulating. Inert gas often, helium, in high temperature, designs while, carbon, dioxide, has been used in past British and French nuclear. Power plants. Nitrogen. Has 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. A eutectic, mixture of, fluoride, salts, such as fly, bay in, a, typical, MSR, the coolant is also, used as a matrix, in which the fissile, material. Is dissolved. Topic. Classification. By generation. Generation. I reactor. Early prototypes. Research, reactors. Non-commercial. Powered producing, reactors. Generation. To reactor, most current, nuclear power plants. 1965. To, 1996. Generation. 3 reactor, evolutionary. Improvements. Of existing, designs. 1996. Present. Generation. IV reactor. Technology. Still under development, unknown start, date possibly. 2030. In. 2003. The French commissariat. Earl energy, atomic a CEA, was the first to refer to gen, 2, types. In nucleonic, suik, the first mentioning, of Gen, 3 was. In 2000. In conjunction, with the launch of the Generation, IV International. Forum, gift plans. Gen. IV was. Named in 2000. By the United. States Department of Energy doe, for developing, new plant types. Topic. Classification. By phase, of fuel. Solid-fueled. Fluid. Fueled. Aqueous. Homogeneous. Reactor. Molten, salt reactor. Gas. Fueled, theoretical. Topic. Classification. By use. Electricity. Nuclear. Power plants, including, small modular reactors. Propulsion. Si nuclear, propulsion. Nuclear. Marine propulsion. Various. Proposed, forms, of rocket propulsion. Other. Uses, of heat. Desalination. Heat. For domestic, and industrial heating. Hydrogen. Production for, use in a hydrogen, economy. Production. Reactors. For transmutation. Of elements. Breeder. Reactors. Are capable, of producing more fissile, material. Than they consume during, the fission, chain reaction by. Converting, fertile. U-238. To pou. 239. Or th. 232. To u. 233. Thus. A uranium, breeder, reactor. Once running can, be refueled, with natural, or even depleted, uranium and, the thorium breeder. Reactor. Can be refueled, with thorium however, an initial, stock of fissile, material, is required. Creating. Various. Radioactive. Isotopes. Such, as americium. For use in smoke detectors, and, cobalt-60. Molybdenum-99. And. Others used, for imaging, and medical, treatment. Production. Of materials. For nuclear weapons such, as weapons-grade. Plutonium. Providing. A source of neutron, radiation for. Example with, the pulsed godiva device, and positron. Radiation eg. Neutron, activation, analysis. And potassium argon, dating. Research. Reactor. Typically. Reactors, used for research and training, materials. Testing, or the production of Radio isotopes for. Medicine, and Industry, these.
Are Much smaller than power reactors. Or those propelling, ships and many are on university. Campuses. There. Are about, 280. Such, reactors operating. In 56. Countries. Some. Operate, with high enriched, uranium. Fuel and international. Efforts are underway to substitute. Low enriched fuel. Topic. Current. Technologies. Pressurized. Water reactors. PWR. These reactors. Use a pressure, vessel to, contain the nuclear, fuel, control. Rods moderator. And coolant. They. Are cooled and moderated. By high-pressure liquid water, the. Hot radioactive. Water that leaves the pressure vessel is looped through a steam, generator which. In turn heats a secondary, non-radioactive. Loop, of water to steam that can run turbines. They. Are the majority of current, reactors, this. Is a thermal, Neutron reactor, design, the newest of which of the vve are 1:200, advanced. Pressurized, water reactor. In the european, pressurized, reactor. United, states naval reactors. Are of this type boiling. Water reactors. BWR. A BWR. Is like a PWR. Without, the steam generator, a, boiling. Water reactor, is. Cooled and moderated. By water like a PWR. But, at a lower pressure which, allows the water to boil inside, the pressure vessel producing. The steam that runs the turbines. Unlike. A PWR. There is no primary, and secondary loop. The. Thermal, efficiency, of these reactors, can be higher and they can be simpler, and even, potentially. More stable, and safe, this. Is a thermal, Neutron reactor, design, the newest of which of the advanced, boiling, water reactor. In the economic. Simplified. Boiling, water reactor. Pressurised. Heavy water, reactor. Phwr. A Canadian, design known, as can do 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. A thermal, Neutron reactor designs. PH. Wr's, 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. Can, do phw, ours have been built, in Canada, Argentina, China. India. Pakistan. Romania. And South, Korea. India. Also operates. A number of phwr, s often termed, can, do derivatives built. After the government of canada halted, nuclear, dealings, with India following, the, 1974. Smiling. Buddha nuclear, weapon, test. Reactor. Bolshoy motion Asti Canal knee high power channel, reactor, RBMK, a Soviet, design built, to produce plutonium, as, well as power. RBMK. Is a water-cooled with a graphite, moderator. RBMK. Tsar, in some respects, similar to can do in that they are refillable, during, power operation. And employ a pressure, tube design, instead, of a PWR. Style, pressure vessel.
However. Unlike, can do they are very unstable enlarged, making. Containment. Buildings, for them expensive, a, series. Of critical safety, floors have also been identified with. The RBMK, design though, some of these were corrected, following, the Chernobyl disaster. The. Main attraction. Is the use of light water and unenriched. Uranium as. Of. 2019. 10 remain open, mostly, due to safety, improvements. And help from international. Safety agencies, such as the DOE. Despite. These safety, improvements. RBMK. Reactors are. Still considered, one of the most dangerous reactor. Designs, in use. RBMK. Reactors were. Deployed, only in the former, Soviet, Union. Gas. Cooled, reactor. GCR. And advanced. Gas-cooled reactor. AGR, 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 ie Magnox. Stations, are either shut down or will be in the near future. However. The AGC ours 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. Liquid. Metal fast breeder reactor. Lmf BR, this. Is a reactor, design that is cooled by liquid metal. Totally, unmoderated, and produces. More fuel than it consumes. They. Are said to breed. Fuel. Because, they produce fissionable. Fuel during operation. Because, of Neutron, capture. 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. Topaz. Nuclear, reactor, BN. 350. A nd B and 600. In USSR, and, super Phoenix in France were 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 was restarted, in May 2010. All. Of them use used liquid sodium, these. Reactors. Are fast, Neutron, not thermal, Neutron, designs, these. Reactors. Come in two types. Led 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, the. Russian alpha class submarine. Uses, a lead bismuth, called fast, reactor, as its main powerplant. Sodium-cooled. Most. LM FB ours 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 sir, care must be taken that, such explosions, would not be vastly, more violent, and for example a leak of superheated.
Fluid From an S cwr. Or PWR. EBRI. The first reactor, to have a core meltdown was, of this type pebble, bed reactors. PB, r these use fuel molded, into ceramic balls and then circulate. Gas through the balls. The. Result, is an efficient, low-maintenance, very. Safe reactor. With inexpensive. Standardized. Fuel. The. Prototype, was the AVR, molten, salt reactors. These dissolve, the fuels in fluoride, salts, or use fluoride, salts, for coolant. These. Have many safety features high. Efficiency. And a high power density suitable. For vehicles. Notably. They, have no high pressures, or flammable, components. In the core, the. Prototype. Was the msre, which, also, used the thorium, fuel cycle as, a, breeder. Reactor, type it reprocesses. The spent fuel extracting. Both uranium and, transfer, onyx leaving, only 0.1%. Of, transuranic waste compared. To conventional. Once-through uranium-fueled. Light, water reactors. Currently, in use a. Separate. Issue is, the radioactive, fission, products. Which are not reprocessing. And need to be disposed, of as with conventional. Reactors, aqueous homogeneous. Reactor. Ahr, these reactors. Use soluble, nuclear, salts, dissolved, in water and mixed, with a coolant, and a neutron, moderator. Topic. Future. And developing, technologies. You. Topic. Advanced. Reactors. More, than a dozen advanced. Reactor, designs, are in various, stages of development. Some. Are evolutionary. From the PWR. BWR. And phwr. Designs. Above, some, are more radical, departures. The. Former, include, the advanced, boiling, water reactor. ABW, are two of which are now operating. With others under construction. And the planned passively, safe, economic. Simplified. Boiling, water reactor. ESB, WR, and AP 1000. Units see nuclear, power 2010, programme. The. Integral, fast reactor, IFR. 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. The. Pebble bed reactor. A high-temperature. Gas-cooled. Reactor. HT GCR, is designed, so high temperatures. Reduce power output, by Doppler broadening of the fuels Neutron, cross-section. It. Uses, ceramic, fuels so it's safe operating. Temperatures, exceed, the power reduction, temperature. Range. Most. Designs, are cooled by inert helium helium. Is not subject, to steam explosions. Resists. Neutron, absorption, leading, to radioactivity. And, does not dissolve contaminants. That can become radioactive. Typical. Designs, have more layers up to 7 of passive, containment. Than light water reactors. Usually, three a, unique. Feature that may aid safety. Is that the fuel balls actually form, the cause mechanism. And-a replaced, one by one as they age, the. Design, of the fuel makes fuel, reprocessing. Expensive. The. Small sealed. Transportable. Autonomous. Reactor, SST. AR is being primarily, researched, and developed in, the u.s. 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. The. Reduced, moderation. Water reactor. Builds upon the advanced, boiling water reactor. A BWR. That is presently, in use it, is not a complete, fast reactor. Instead, using, mostly epithermal, neutrons which. Are between thermal, and fast neutrons. In speed. The. Hydrogen, moderated. Self-regulating. Nuclear, power module, hpm, is a reactor. Design emanating. From the Los Alamos, National Laboratory. That uses, uranium, hydride, as fuel. 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 four times more abundant than uranium can. Be used to breed u, 233. Nuclear, fuel. U. 233. Is also, believed to have favorable, nuclear, properties, as compared, to traditionally. Used. U-235. Including. Better Neutron, economy and, lower production of long-lived, tranche or a niche wastes. Advanced. Heavy water reactor.
Ahw Are, a proposed. Heavy water moderated. Nuclear, power reactor, that will be the next generation design. Of the phwr. Type. Under. Development, in the Bava Atomic, Research Center. Barque India. Ka. Mi, ni a unique. Reactor. Using, uranium. 233. Isotope. For fuel. Built in India by, bark and Indira Gandhi, Centre for atomic research IG, ciear. India. Is also planning to build fast, breeder reactors. Using the thorium, uranium. 233. Fuel. Cycle, the. FBT are fast, breeder test, reactor, in operation. At Kalpakkam, India, uses, plutonium. As a fuel, in liquid, sodium as a coolant. Topic. 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 had generally, considered, 2nd or 3rd generation, systems. With the first generation. Systems, having, been retired sometime, 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. Gas. Cooled, fast, reactor. Lead. Cooled fast reactor. Molten, salt reactor. Sodium-cooled. Fast. Reactor. Supercritical. Water, reactor. Very. High temperature. Reactor. Topic. Generation. V+, reactors. Generation. V reactors. Are 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. Or uranium, solution. 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, light bulb 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. This. Reactor, design could also function, as a rocket engine, as featured. In Harry Harrison's. 1976. Science, fiction, novel Skyfall. 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 weakening. Most reactor, materials, and therefore, is the flux would be similar, to that expected. In fusion, reactors, it would require similar. Materials. To those selected, by the International. Fusion, materials, irradiation, facility. Gas. Call em reactor. As in, the gas core reactor, but with photovoltaic, arrays. Converting. The UV light directly, to electricity. This. Approach is similar to the experimentally, proved. Photoelectric. Effect that, would convert the x-rays generated. From a neutronic, fusion, into electricity. By passing, the high-energy photons. Through an array of conducting. Foils, to transfer, some of their energy to, electrons, the energy, of the photon, captured. Electrostatically. Similar, to a capacitor. Since. X-rays, can go through far greater material. Thickness than electrons, many, hundreds, or thousands, of layers are needed to absorb the x-rays. Fish. And fragment, reactor, efficient. Fragment, reactor, is a nuclear, reactor, that generates, electricity, by, decelerating. An ion beam of fish and byproducts. Instead, of using nuclear, reactions, to generate, heat, by. Doing so, it bypasses, the Carnot, cycle, and can achieve efficiencies. Of up to 90 percent instead, of 40, to 45. Percent attainable. By efficient, turbine, driven thermal, reactors. The. Fish and fragment, ion beam would be passed through a magnetohydrodynamic. Generator. To produce electricity. Hybrid. Nuclear fusion, would, use the neutrons, emitted by, fusion, to fish in a blanket of fertile, material like. You, 238. Or th. 232. And transmute. Other reactors. Spent nuclear fuel nuclear. Waste, into, relatively, more benign isotopes. Topic. 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 only recently, reactors. Have been able to release more energy than, the amount of energy used, in the process. Despite. Research, having started, in the 1950s. No, commercial. Fusion reactor, is expected. Before 2050. The. ITER project is.
Currently Leading the effort to harness, fusion, power. Topic. 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. 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 into pellet, form, these. Pellets, are stacked into tubes which are then sealed in cold fuel, rods. Many. Of these fuel, rods are used in each nuclear, reactor. 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 fueled. By highly, enriched weapons-grade. 90%. Enrichment, uranium. Theft. Risk of this fuel potentially. Used in the production of a nuclear, weapon has led to campaigns, advocating. Conversion, of this type of reactor, to low enrichment, uranium, which poses less threat of proliferation, fissile. U. 235. And non-fissile. But fissionable. Infertile u. 238. Are both used in the fission process. U. 235. Is fissionable by, thermal, ie 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 fish in. U-235. When, it is moving at this same vibrational. Speed, on the. Other hand you. 238. Is more likely, to capture, a neutron, when the neutron is moving, very fast. This. You. 239. Atom, will soon decay into plutonium. 239. Which, is another fuel. Pute. 239. Is a viable fuel, and must be accounted, for even, when a highly, enriched uranium fuel, is used. Plutonium. Fishin's, will dominate, the you. 235. Fishin's 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. 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 pou. 239. Breeding. Fuel. In. Thorium. Fuel cycle thorium. 232. Absorbs. A neutron in, either a fast, or thermal, reactor. The. Thorium. 233. Beta decays, to protactinium. 233. And then to uranium. 233. Which, in turn is used as fuel. Hence. Like your. 238. Thorium. 232. Is, a fertile, material. Topic. Fuelling, 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 reactors, 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. 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, fission, has taken, place the build-up of long-lived, neutron, absorbing, fission, byproducts. Impedes, the chain reaction. The. Fraction, of the reactors, fuel core replaced, during refueling, is typically, one-fourth, for a boiling, water reactor, and. One-third, for a pressurized, water reactor. The. Disposition. And storage, of this spent fuel is one of the most challenging aspects. Of the operation, of a commercial nuclear. Power plant. This. Nuclear, waste is, highly, radioactive and. Its toxicity, presents. A danger for thousands. Of years not all reactors, need to be shut down for, refueling, for example, pebble, bed reactors. RBMK. Reactors. Molten. Salt reactors, Magnox. AGR. & CANDU, reactors, allow fuel, to be shifted, through the reactor while, it is running. In a can-do, reactor, this also allows individual. Fuel elements, to be situated, within the reactor, core that are best suited to the amount of. U-235. In, the fuel element. 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. Burnup, is commonly, expressed, as megawatt, days thermal, per metric tonne of initial, heavy metal. Topic. Nuclear. Safety, concerns. And controversy. Nuclear. Safety covers, the actions, taken, to prevent nuclear, and radiation accidents, and, incidents or, to limit their consequences. The. Nuclear, power industry has, improved, the safety and performance of, reactors, and has proposed, new safer. But generally, untested, reactor, designs, but there is no guarantee that the reactors, will be designed, built, and operated correctly.
Mistakes. Do occur and the designers, of reactors. At Fukushima in, Japan did. Not anticipate, that, a tsunami, generated, by an earthquake would, disable the backup systems. That were supposed, to stabilize, the reactor after, the earthquake, despite, multiple warnings. By the NRG, and, the Japanese, Nuclear, Safety, Administration. According. To UBS, AG the Fukushima. I nuclear accidents, have. Cast doubt on whether, even an advanced, economy like, Japan, can master, nuclear, safety. Catastrophic. Scenarios. Involving terrorist. Attacks, are also conceivable. An interdisciplinary. Team, from, MIT has, estimated, that, given the expected, growth of nuclear power from. 2005. To 2015, 5, at least four serious, nuclear accidents. Would be expected, in that period. Topic. Nuclear. Accidents. And controversy. Some, serious, nuclear, and radiation accidents, have, occurred, nuclear. Power plant, accidents. Include, the sl1, accident. 1961. The Three Mile Island accident. 1979. Chernobyl. Disaster. 1986. And the Fukushima. Daiichi nuclear disaster. 2011. Nuclear-powered. Submarine, mishaps, include, the k-19, reactor. Accident. 1961. The, k-27. Reactor, accident. 1968. And the k. 431. Reactor. Accident. 1985. Nuclear. Reactors, have been launched, into Earth orbit at least 34. Times a. Number. Of incidents, connected with the unmanned nuclear, reactor, powered, Soviet, ro rs80, radar. Satellite, program, resulted, in spent nuclear fuel, reentering. The Earth's atmosphere from orbit. Topic. Natural. Nuclear, reactors. Although. Nuclear, fission, reactors, are often thought of as being solely, a product, of modern technology. The first nuclear, fission, reactors, were in fact naturally, occurring a, natural. Nuclear fission. Reactor, can occur under certain, circumstances. That mimic the conditions in, a constructed. Reactor. 15. Natural, fission, reactors, have so far been found in, three separate, ore deposits. At the Oklo uranium. Mine in Gabon, West Africa. First. Discovered, in, 1972. By French physicist, Francis Perrin. They are collectively, known as the Oklo fossil, reactors. Self-sustaining. Nuclear fission. Reactions, took place in these reactors, approximately. 1.5. Billion years ago and ran for a few hundred thousand, years averaging. 100. Kilowatts, 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, such. Reactors, can, no longer form, on earth in its present, geologic, period. Radioactive. Decay of formerly, abundant. Uranium-235. Over, the timespan, of hundreds, of millions of years has reduced, the proportion, of this naturally-occurring, fissile. Isotope. 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, 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. Topic. Emissions. Nuclear. Reactors produce, tritium, as part of normal operations. Which is eventually released, into, the environment in, trace quantities, as. An. Isotope, of hydrogen tritium. Tea, frequently. Binds to oxygen and, forms t2o. This. Molecule, is chemically, identical to. H2o, and, so is both colorless, and odorless however. The additional neutrons. In the hydrogen, nuclei, caused the tritium to undergo, beta decay, with a half-life of. 12.3, years. Despite. Being measurable. The tritium, released by nuclear, power plants. Is minimal, the. United states NRC. Estimates, that a person, drinking, water for, one year out of a well contaminated. By what they would consider to be a significant. Tritiated, water spill. Would receive a radiation. Dose of, 0.3. Miller M for. Comparison. This is an order of magnitude less than the for Miller M a person. Receives on a round-trip, flight, from Washington, DC to, Los Angeles a, consequence. Of less atmospheric. Protection, against, highly energetic, cosmic, rays at high altitudes. The amounts, of strontium-90, released, from nuclear, power plants. Under normal operations. Is so low as to be undetectable. Above natural, background radiation. Detectable. Strontium-90. In groundwater and, the general environment can, be traced to weapons, testing, and the Chernobyl, accident that, occurred during the, mid 20th, century. Topic. C also. The, atomic age Wikipedia.
Book. List. Of nuclear, reactors. List. Of small nuclear, reactor designs. List, of United, States naval. Reactors. Neutron. Transport. Nuclear, marine propulsion. Nuclear power by country. One. Less nuclear, power plant. Radioisotope. Thermoelectric generator. Safety. Engineering. Sigh. Honor our nuclear, power plants. Small. Modular, reactor. Thorium-based. Nuclear power. Traveling. Wave reactor tour. World nuclear, industry, status, report.
2019-01-15 21:28
