Pebble-bed Reactor
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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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Neutron Moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely more susceptible than fast neutrons to propagate a nuclear chain reaction of uranium-235 or other fissile isotope by colliding with their atomic nucleus. Water (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives. Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility. Moderation Neutrons are normally bound into an atomic nucleus, and do not exist free for long in nature. The unbound neutron has a half-life of 10 minutes and 11 seconds. The release of neutrons from the nucleus requires exceeding the binding energy ...
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Nuclear Power Plant
A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generator that produces electricity. , the International Atomic Energy Agency reported there were 422 nuclear power reactors in operation in 32 countries around the world, and 57 nuclear power reactors under construction. Nuclear plants are very often used for base load since their operations, maintenance, and fuel costs are at the lower end of the spectrum of costs. However, building a nuclear power plant often spans five to ten years, which can accrue to significant financial costs, depending on how the initial investments are financed. Nuclear power plants have a carbon footprint comparable to that of renewable energy such as photovoltaic power station, solar farms and wind farms, and much lower than fossil fuels such as gas-fired ...
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General Atomics
General Atomics is an American energy and defense corporation headquartered in San Diego, California, specializing in research and technology development. This includes physics research in support of nuclear fission and nuclear fusion energy. The company also provides research and manufacturing services for remotely operated surveillance aircraft, including the General Atomics MQ-1 Predator, Predator drones, airborne sensors, and advanced electric, electronic, wireless, and laser technologies. History General Atomics (GA) was founded on July 18, 1955, in San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ..., California, by Frederic de Hoffmann with assistance from notable physicists Edward Teller and Freeman Dyson. Originally the company was part of the General Atomic divi ...
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University Of California At Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant university and the founding campus of the University of California system. Its fourteen colleges and schools offer over 350 degree programs and enroll some 31,800 undergraduate and 13,200 graduate students. Berkeley ranks among the world's top universities. A founding member of the Association of American Universities, Berkeley hosts many leading research institutes dedicated to science, engineering, and mathematics. The university founded and maintains close relationships with three national laboratories at Berkeley, Livermore and Los Alamos, and has played a prominent role in many scientific advances, from the Manhattan Project and the discovery of 16 chemical elements to breakthroughs in computer science and genomics. Berkeley is also k ...
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Massachusetts Institute Of Technology
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the most prestigious and highly ranked academic institutions in the world. Founded in response to the increasing industrialization of the United States, MIT adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. MIT is one of three private land grant universities in the United States, the others being Cornell University and Tuskegee University. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River, and encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes. , 98 ...
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HTR-10
HTR-10 is a 10 MWt prototype pebble bed reactor at Tsinghua University in China. Construction began in 1995, achieving its first criticality in December 2000, and was operated in full power condition in January 2003. Two HTR-PM reactors, scaled up versions of the HTR-10 with 250-MWt capacity, were installed at the Shidao Bay Nuclear Power Plant near the city of Rongcheng in Shandong Province and achieved first criticality in september 2021. Development HTR-10 is modeled after the German HTR-MODUL. Like the HTR-MODUL, HTR-10 is claimed to be fundamentally safer, potentially cheaper and more efficient than other nuclear reactor designs. Outlet temperature ranges between , which allows these reactors to generate hydrogen as a byproduct efficiently, thus supplying inexpensive and non-polluting fuel for fuel cell powered vehicles. HTR-10 is a pebble-bed reactor HTGR utilizing spherical fuel elements with ceramic coated fuel particles. The reactor core has a diameter of 1 ...
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China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and borders fourteen countries by land, the most of any country in the world, tied with Russia. Covering an area of approximately , it is the world's third largest country by total land area. The country consists of 22 provinces, five autonomous regions, four municipalities, and two Special Administrative Regions (Hong Kong and Macau). The national capital is Beijing, and the most populous city and financial center is Shanghai. Modern Chinese trace their origins to a cradle of civilization in the fertile basin of the Yellow River in the North China Plain. The semi-legendary Xia dynasty in the 21st century BCE and the well-attested Shang and Zhou dynasties developed a bureaucratic political system to serve hereditary monarchies, or dyna ...
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PBMR
The Pebble Bed Modular Reactor (PBMR) is a particular design of pebble bed reactor developed by South African company PBMR (Pty) Ltd from 1994 until 2009. PBMR facilities include gas turbine and heat transfer labs at the Potchefstroom Campus of North-West University, and at Pelindaba, a high pressure and temperature helium test rig, as well as a prototype fuel fabrication plant. A planned test reactor at Koeberg was not built. Reactor Design The PBMR is characterised by inherent safety features, which mean that no human error or equipment failure can cause an accident that would harm the public. Heat from the PBMR can be used for a variety of industrial process applications, including process steam for cogeneration applications, in-situ oil sands recovery, ethanol applications, refinery and petrochemical applications. The high temperature heat can also be used to reform methane to produce syngas (where the syngas can be used as feedstock to produce hydrogen, ammonia and metha ...
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South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countries of Namibia, Botswana, and Zimbabwe; and to the east and northeast by Mozambique and Eswatini. It also completely enclaves the country Lesotho. It is the southernmost country on the mainland of the Old World, and the second-most populous country located entirely south of the equator, after Tanzania. South Africa is a biodiversity hotspot, with unique biomes, plant and animal life. With over 60 million people, the country is the world's 24th-most populous nation and covers an area of . South Africa has three capital cities, with the executive, judicial and legislative branches of government based in Pretoria, Bloemfontein, and Cape Town respectively. The largest city is Johannesburg. About 80% of the population are Black South Afri ...
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Rudolf Schulten
Rudolf Schulten (16 August 1923 – 27 April 1996)—professor at RWTH Aachen University—was the main developer of the pebble bed reactor design, which was originally invented by Farrington Daniels. Schulten's concept compacts silicon carbide-coated uranium granules into hard, billiard-ball-like graphite spheres to be used as fuel for a new high temperature, helium-cooled type of nuclear reactor. AVR reactor The idea took root and in due course a 46 MWth (megawatt thermal) experimental pebble bed reactor (the Arbeitsgemeinschaft Versuchsreaktor, or AVR reactor) was built at the Jülich Research Centre in Jülich, West Germany. It operated for 21 years but was shut down in the wake of Chernobyl. HTR-MODUL project Some of the last pebble fuel tested in the AVR was for a low enriched uranium (LEU) fuel cycle anticipated for use in the HTR-MODUL project design by Interatom/SIEMENS. South African Pebble Bed Modular Reactor Based on the AVR, South Africa along with internati ...
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AVR Reactor
The AVR reactor (german: Arbeitsgemeinschaft Versuchsreaktor) was a prototype pebble-bed reactor, located immediately adjacent to Jülich Research Centre in West Germany, constructed in 1960, grid connected in 1967 and shut down in 1988. It was a 15MWe, 46 MWt test reactor used to develop and test a variety of fuels and machinery. The AVR was based on the concept of a "Daniels pile" by Farrington Daniels, the inventor of pebble bed reactors. Rudolf Schulten is commonly recognized as the intellectual father of the reactor. A consortium of 15 community electric companies owned and operated the plant. Over its lifetime the reactor had many accidents, earning it the name "shipwreck." From 2011 to 2014, outside experts examined the historical operations and operational hazards and described serious concealed problems and wrongdoings in their final 2014 report. For example, in 1978 operators bypassed reactor shutdown controls to delay an emergency shutdown during an accident for six ...
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Germans
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