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Online Refuelling
In nuclear power technology, online refuelling is a technique for changing the fuel of a nuclear reactor while the reactor is critical. This allows the reactor to continue to generate electricity during routine refuelling, and therefore improve the availability and profitability of the plant. Benefits of online refuelling Online refuelling allows a nuclear reactor to continue to generate electricity during periods of routine refuelling, and therefore improves the availability and therefore the economy of the plant. Additionally, this allows for more flexibility in reactor refuelling schedules, exchanging a small number of fuel elements at a time rather than high-intensity offline refuelling programmes. The ability to refuel a reactor while generating power has the greatest benefits where refuelling is required at high frequency, for example during the production of plutonium suitable for nuclear weapons during which low-burnup fuel is required from short irradiation periods in a ...
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Nuclear Power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by nuclear ''fission'' of uranium and plutonium in nuclear power plants. Nuclear ''decay'' processes are used in niche applications such as radioisotope thermoelectric generators in some space probes such as ''Voyager 2''. Generating electricity from fusion power, ''fusion'' power remains the focus of international research. Most nuclear power plants use thermal reactors with enriched uranium in a Nuclear fuel cycle#Once-through nuclear fuel cycle, once-through fuel cycle. Fuel is removed when the percentage of neutron poison, neutron absorbing atoms becomes so large that a nuclear chain reaction, chain reaction can no longer be sustained, typically three years. It is then cooled for several years in on-site spent fuel pools before being tr ...
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Pressurized Water Reactor
A pressurized water reactor (PWR) is a type of light-water reactor, light-water nuclear reactor. PWRs constitute the large majority of the world's nuclear power plants (with notable exceptions being the UK, Japan and Canada). In a PWR, the primary nuclear reactor coolant, coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy released by the Nuclear fission, fission of atoms. The heated, high pressure water then flows to a Water-tube boiler, steam generator, where it transfers its thermal energy to lower pressure water of a secondary system where steam is generated. The steam then drives turbines, which spin an electric generator. In contrast to a boiling water reactor (BWR), pressure in the primary coolant loop prevents the water from boiling within the reactor. All light-water reactors use ordinary water as both coolant and neutron moderator. Most use anywhere from two to four vertically mounted steam generators; VVER reactors use horizo ...
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Molten Salt Reactor
A molten salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a molten salt mixture. Only two MSRs have ever operated, both research reactors in the United States. The 1950's Aircraft Reactor Experiment was primarily motivated by the compact size that the technique offers, while the 1960's Molten-Salt Reactor Experiment aimed to prove the concept of a nuclear power plant which implements a thorium fuel cycle in a breeder reactor. Increased research into Generation IV reactor designs began to renew interest in the technology, with multiple nations having projects, and , China is on the verge of starting its TMSR-LF1 thorium MSR. MSRs are considered safer than conventional reactors because they operate with fuel already in a molten state, and in some designs in the event of an emergency, the fuel mixture is designed to drain from the core to a containment vessel where it will solidify in fuel drain tanks. This pre ...
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BN-800
The BN-800 reactor (Russian: реактор БН–800) is a sodium-cooled fast breeder reactor, built at the Beloyarsk Nuclear Power Station, in Zarechny, Sverdlovsk Oblast, Russia. The reactor is designed to generate 880 MW of electrical power. The plant was considered part of the weapons-grade Plutonium Management and Disposition Agreement signed between the United States and Russia, with the reactor being part of the final step for a plutonium-burner core (a core designed to burn and, in the process, destroy, and recover energy from, plutonium) The plant reached its full power production in August 2016. According to Russian business journal ''Kommersant'', the BN-800 project cost 140.6 billion rubles (roughly 2.17 billion dollars). Design The plant is a pool-type LMFBR, in which the reactor, coolant pumps, intermediate heat exchangers and associated piping are all located in a common liquid sodium pool. This is essentially the same general design as EBR-II, which entered ...
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BN-600
The BN-600 reactor is a Liquid metal cooled reactor, sodium-cooled fast breeder reactor, built at the Beloyarsk Nuclear Power Station, in Zarechny, Sverdlovsk Oblast, Russia. Designed to generate electrical power of 600 Watt (unit), MW in total, the plant dispatches 560 MW to the Ural Mountains, Middle Urals power grid. It has been in operation since 1980 and represents an evolution on the preceding BN-350 reactor. In 2014, its larger sister reactor, the BN-800 reactor began operation. The plant is a pool type LMFBR, where the reactor, coolant pumps, intermediate heat exchangers and associated piping are all located in a common liquid sodium pool. This is essentially the same general design as EBR-II, which went into service in 1963. The reactor system is housed in a concrete rectilinear building, and provided with filtration and gas containment features. In the first 15 years of operation, there have been 12 incidents involving sodium/water interactions from tube break ...
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BN-350
The BN-350 is a sodium-cooled, fast reactor located at the ''Mangyshlak Nuclear Power Plant'', located in Aktau (formerly known as Shevchenko under the control of the USSR in 1964–1992), Kazakhstan, on the shore of the Caspian Sea. Construction of the BN-350 fast breeder reactor began in 1964, and the plant first produced electricity in 1973. In addition to providing power for the city (350 MWe), BN-350 was also used for producing plutonium and for desalination to supply fresh water (120,000 m³ fresh water/day) to the city. Planning and design The prototypes for the development of the BN-350 reactor were the experimental reactor BR-5 , built in 1959 on the territory of the Institute of Physics and Power Engineering (IPPE, Obninsk, Kaluga region ), and the research reactor BOR-60 , introduced at RIAR in 1969. (Melekess, now Dimitrovgrad , Ulyanovsk region ) . The development of all power reactors was carried out under the scientific guidance of IPPE. A three-circuit react ...
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UNGG Reactor
The UNGG (''Uranium Naturel Graphite Gaz'') is an obsolete nuclear power reactor design developed in France. It was graphite neutron moderator, moderated, cooled by carbon dioxide, and fueled with natural uranium metal. The first generation of French nuclear power stations were UNGGs, as was Vandellos unit 1 in Spain. Of the ten units built, all were shut down by the end of 1994, most for economic reasons due to staffing costs. The UNGG and the Magnox are the two main types of gas cooled reactor (GCR). A UNGG reactor is often referred to simply as a ''GCR'' in English documents, or sometimes loosely as a ''Magnox''. It was developed independently of and in parallel to the British Magnox design, and to meet similar requirements of simultaneous production of electric power and plutonium. The first UNGG reactors at Marcoule used horizontal fuel channels and a concrete containment structure. Chinon Nuclear Power Plant, Chinon A1 used vertical fuel channels, as did the British Magnox ...
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RBMK
The RBMK (russian: реактор большой мощности канальный, РБМК; ''reaktor bolshoy moshchnosti kanalnyy'', "high-power channel-type reactor") is a class of graphite-moderated nuclear power reactor designed and built by the Soviet Union. The name refers to its design where, instead of a large steel pressure vessel surrounding the entire core, the core is surrounded by a cylindrical annular steel tank inside a concrete vault and each fuel assembly is enclosed in an individual 8 cm (inner) diameter pipe (called a "technological channel"). The channels also contain the coolant, and are surrounded by graphite. The RBMK is an early Generation II reactor and the oldest commercial reactor design still in wide operation. Certain aspects of the original RBMK reactor design, such as the large positive void coefficient, the 'positive scram effect' of the control rods and instability at low power levels, contributed to the 1986 Chernobyl disaster, in which ...
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CANDU Reactor
The CANDU (Canada Deuterium Uranium) is a Canadian pressurized heavy-water reactor design used to generate electric power. The acronym refers to its deuterium oxide ( heavy water) moderator and its use of (originally, natural) uranium fuel. CANDU reactors were first developed in the late 1950s and 1960s by a partnership between Atomic Energy of Canada Limited (AECL), the Hydro-Electric Power Commission of Ontario, Canadian General Electric, and other companies. There have been two major types of CANDU reactors, the original design of around 500  MWe that was intended to be used in multi-reactor installations in large plants, and the rationalized CANDU 6 in the 600 MWe class that is designed to be used in single stand-alone units or in small multi-unit plants. CANDU 6 units were built in Quebec and New Brunswick, as well as Pakistan, Argentina, South Korea, Romania, and China. A single example of a non-CANDU 6 design was sold to India. The multi-unit design was used o ...
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Generation III Reactor
Generation III reactors, or Gen III reactors, are a class of nuclear reactors designed to succeed Generation II reactors, incorporating evolutionary improvements in design. These include improved fuel technology, higher thermal efficiency, significantly enhanced safety systems (including passive nuclear safety), and standardized designs intended to reduce maintenance and capital costs. They are promoted by the Generation IV International Forum (GIF). The first Generation III reactors to begin operation were Kashiwazaki 6 and 7 advanced boiling water reactors (ABWRs) in 1996 and 1997. Since 2012, both have been shut down due to security concerns. Due to the prolonged period of stagnation in the construction of new reactors and the continued (albeit declining) popularity of Generation II/II+ designs in new construction, relatively few third generation reactors have been built. Overview The older Gen II reactors comprise the vast majority of current nuclear reactors. Gen III re ...
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Pebble-bed Reactor
The pebble-bed reactor (PBR) is a design for a graphite- moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative. The basic design of pebble-bed reactors features spherical fuel elements called pebbles. These tennis ball-sized pebbles (approx. in diameter) are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro-fuel particles called TRISO particles. These TRISO fuel particles consist of a fissile material (such as 235U) surrounded by a ceramic layer coating of silicon carbide for structural integrity and fission product containment. In the PBR, thousands of pebbles are amassed to create a reactor core, and are cooled by a gas, such as helium, nitrogen or carbon dioxide, that does not react chemically with the fuel elements. Other coolants such as FLiBe (molten fluoride, lithium, beryllium salt)) have also been suggeste ...
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