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Encyclopedia > Generation IV reactor

Generation IV reactors (Gen IV) 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.


An Integrated Nuclear Energy Model is central to standardized and credible economic evaluation of Generation IV nuclear energy systems. The innovative nuclear systems considered within Generation IV require new tools for their economic assessment, since their characteristics differ significantly from those of current Generation II & III nuclear power plants. The current economic models were not designed to compare alternative nuclear technologies or systems but rather to compare nuclear energy with fossil alternatives.

Contents


Participating countries

Reactor types

Many reactor types were considered initially, however the list was downsized to focus on the most promising technolgies and those that could most likely meet the goals of the Gen IV intitiative. Three sytems are thermal reactors and three are fast reactors. The VHTR is also being researched for potentially providing high quality process heat for hydrogen production. The fast reactors offer the possibility of burning actinides to further reduce waste and of being able to breed more fuel than they consume.


Thermal reactors

Very-High-Temperature Reactor (VHTR)

Main articles: Very high temperature reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

The Very High Temperature Reactor concept utilizes a graphite-moderated core with a once-through uranium fuel cycle. This reactor design envisions an outlet temperature of 1,000°C. The reactor core can be either a prismatic-block or a pebble-bed design. The high temperatures enable applications such as process heat or hydrogen production via the thermo-chemical iodine-sulfur process. It would also be passively safe. The Very High Temperature Reactor is a Generation IV reactor concept that uses a graphite-moderated reactor with a once-through uranium fuel cycle. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block 3, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... General Name, Symbol, Number iodine, I, 53 Chemical series halogens Group, Period, Block 17, 5, p Appearance violet-dark gray, lustrous Atomic mass 126. ... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ...


Supercritical-Water-Cooled Reactor (SCWR)

Main articles: Supercritical water reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

The Supercritical water reactor (SCWR) is a concept that uses supercritical water as the working fluid. SCWRs are basically LWRs operating at higher pressure and temperatures with a direct, once-through cycle. As most commonly envisioned, it would operate on a direct cycle, much like a BWR, but since it uses supercritical water (not to be confused with critical mass) as the working fluid, would have only one phase present, like the PWR. It could operate at much higher temperatures than both current PWRs and BWRs. The Supercritical water reactor (SCWR) is a Generation IV reactor concept that uses supercritical water as the working fluid. ... A supercritical fluid is any substance at a temperature and pressure above its thermodynamic critical point. ... A boiling water reactor (BWR) is a light water reactor design used in some nuclear power stations. ... A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ... A pressurized water reactor (PWR) is a type of nuclear power reactor that uses ordinary (light) water for both coolant and for neutron moderator. ...


Supercritical water-cooled reactors (SCWRs) are promising advanced nuclear systems because of their high thermal efficiency (i.e., about 45% vs. about 33% efficiency for current light water reactors (LWR) and considerable plant simplification. A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water (as opposed to heavy water) as its neutron moderator. ...


The main mission of the SCWR is generation of low-cost electricity. It is built upon two proven technologies, LWRs, which are the most commonly deployed power generating reactors in the world, and supercritical fossil fuel fired boilers, a large number of which are also in use around the world. The SCWR concept is being investigated by 32 organizations in 13 countries. Electricity is a property of matter that results from the presence of electric charge. ... Coal rail cars in Ashtabula, Ohio Fossil fuels, also known as mineral fuels, are hydrocarbon-containing natural resources such as coal, petroleum and natural gas. ... A boiler is a closed vessel in which water or other fluid is heated under pressure. ...


Molten Salt Reactor (MSR)

Main articles: Molten salt reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

A molten salt reactor is a type of nuclear reactor where the working fluid is a molten salt. There have been many designs put forward for this type of reactor and a few prototypes built. The early concepts and many current ones had the nuclear fuel dissolved in the molten fluoride salt working fluid as uranium tetrafluoride (UF4), the fluid would reach criticallity by flowing into a graphite core which also served as the moderator. Many current concepts rely on fuel that is dispersed in a graphite matrix with the molten salt providing low pressure, high temperature cooling. A molten salt reactor is a type of nuclear reactor where the working fluid is a molten salt. ... Core of a nuclear reactor 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 explosion, where the chain reaction occurs in a split second). ... Working mass is a mass against which a system operates in order to produce acceleration. ... Nuclear Fuel is used to generate Nuclear power. ... The neutrality of this article is disputed. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block 3, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... A sphere of plutonium surrounded by neutron-reflecting blocks of tungsten carbide. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... In nuclear engineering, a neutron moderator is a medium which reduces the velocity of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction. ...


Fast reactors

Gas-Cooled Fast Reactor (GFR)

Main articles: Gas cooled fast reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

The Gas-Cooled Fast Reactor (GFR) system features a fast-neutron spectrum and closed fuel cycle for efficient conversion of fertile uranium and management of actinides. The reactor is a, helium-cooled system operating with an outlet temperature of 850°C using a direct Brayton cycle gas turbine for high thermal efficiency. Several fuel forms are being considered for their potential to operate at very high temperatures and to ensure an excellent retention of fission products: composite ceramic fuel, advanced fuel particles, or ceramic clad elements of actinide compounds. Core configurations are being considered based on pin- or plate-based fuel assemblies or prismatic blocks. 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 nuclear fuel cycle consists of front end steps that lead to the preparation of uranium for use as fuel for reactor operation and back end steps that are necessary to safely manage, prepare, and dispose of radioactive waste. ... Fertile material is a term used to describe nuclides which generally themselves do not undergo induced fission (fissionable by thermal neutrons) but from which fissile material is generated by neutron absorption and subsequent nuclei conversions. ... The actinide series encompasses the 15 chemical elements that lie between actinium and lawrencium on the periodic table with atomic numbers 89 - 103. ... General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ... The Brayton cycle is a cyclic process generally associated with the gas turbine. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... In general fission is a splitting or breaking up into parts. ... The word ceramic is derived from the Greek word Κεραμεικος (the name of a suburb of Athens), and in its strictest sense refers to clay in all its forms. ...


Sodium-Cooled Fast Reactor (SFR)

Main articles: Integral Fast Reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

The SFR is a design for a nuclear reactor with a specialized nuclear fuel cycle. A prototype of the reactor was built, but the project was cancelled before it could be copied elsewhere. The Integral Fast Reactor or Advanced Liquid-Metal Reactor was a design for a nuclear reactor with a specialized nuclear fuel cycle. ... The nuclear fuel cycle consists of front end steps that lead to the preparation of uranium for use as fuel for reactor operation and back end steps that are necessary to safely manage, prepare, and dispose of radioactive waste. ...


This reactor concept is cooled by liquid sodium and fueled by a metallic alloy of uranium and plutonium. The fuel is contained in steel cladding with liquid sodium filling in the space between the fuel and the cladding. General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Atomic mass 22. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block 3, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... 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. ...


The goals are to increase the efficiency of uranium usage by breeding plutonium and eliminating the need for transuranic isotopes ever to leave the site. The reactor design uses an unmoderated core running on fast neutrons, designed to allow any transuranic isotope to be consumed (and in some cases used as fuel). In addition to the benefits of removing the long half-life transuranics from the waste cycle, the SFR fuel expands when the reactor overheats, and the chain reaction automatically slows down. In this manner, it is passively safe. The fast breeder or fast breeder reactor (FBR) is a type of fast neutron reactor that produces more fissile material than it consumes. ... In chemistry, transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, the atomic number of Uranium. ... 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. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...


Lead-Cooled Fast Reactor (LFR)

Main articles: Lead cooled fast reactor, and [[{{{2}}}]], and [[{{{3}}}]], and [[{{{4}}}]], and [[{{{5}}}]]

The Lead-cooled Fast Reactor features a fast-spectrum lead or lead/bismuth eutectic liquid metal-cooled reactor with a closed fuel cycle. Options include a range of plant ratings, including a "battery" of 50 to 150 MW of electricity that features a very long refueling interval, a modular system rated at 300 to 400 MW, and a large monolithic plant option at 1,200 MW. (The term battery refers to the long-life, factory-fabricated core, not to any provision for electrochemical energy conversion.) The fuel is metal or nitride-based containing fertile uranium and transuranics. The LFR is cooled by natural convection with a reactor outlet coolant temperature of 550 degrees C, possibly ranging up to 800 degrees C with advanced materials. The higher temperature enables the production of hydrogen by thermochemical processes. 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. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous reddish white Atomic mass 208. ... A eutectic or eutectic mixture is a mixture of two or more elements which has a lower melting point than any of its constituents. ... The nuclear fuel cycle consists of front end steps that lead to the preparation of uranium for use as fuel for reactor operation and back end steps that are necessary to safely manage, prepare, and dispose of radioactive waste. ... Fertile material is a term used to describe nuclides which generally themselves do not undergo induced fission (fissionable by thermal neutrons) but from which fissile material is generated by neutron absorption and subsequent nuclei conversions. ... In chemistry, transuranium elements (also known as transuranic elements) are the chemical elements with atomic numbers greater than 92, the atomic number of Uranium. ... Convection is the transfer of heat by currents within a fluid. ...


These systems offer significant advances in sustainability, safety and reliability, economics, proliferation resistance and physical protection.


See also

Core of a nuclear reactor 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 explosion, where the chain reaction occurs in a split second). ... Nuclear materail consists of materials used in nuclear systems. ... Atomic physics (or atom physics) is physics of the electron hull of atoms. ...

External links

  • Generation IV International Forum (GIF)
  • U.S. Department of Energy Office of Nuclear Energy, Science and Technology
  • Gen IV presentation

  Results from FactBites:
 
U.S. Nuclear Reactors (1517 words)
Of these 104 reactors, 69 are categorized a pressurized water reactors (PWRs) totaling 65,100 net megawatts (electric) and 35 units are boiling water reactors (BWR) totaling 32,300 net megawatts (electric).
New Reactor Designs: This feature article focuses mainly on the new Generation IV reactors, but also discusses other designs that could have an impact on the future of the U.S. and international nuclear market.
All of the licensed U.S. commercial reactors are required to have a containment dome to protect the reactor from external damage and to prevent the release of radiation.
  More results at FactBites »

 
 

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