• light water g
  • It occurred on 25-26 April 1986 in the No.4 light water graphite moderated reactor at the Chernobyl Nuclear Power Plant near Pripyat, a town in northern Ukrainian Soviet Socialist Republic which was part of the Soviet Union (USSR), approximately 104 km north of Kiev. (wikipedia.org)
  • vessel
  • While some LMRs are of the loop type, equipped with heat exchanger s and pumps outside the primary reactor vessel, others are of the pool variety, featuring a large volume of primary sodium in a pool that also contains the primary pumps and the primary-to-secondary heat exchanger. (britannica.com)
  • A reactor of this kind consists of a tank, or calandria vessel, containing a cold heavy water moderator at atmospheric pressure . (britannica.com)
  • Water coolant travels around the primarily circuit, through the reactor pressure vessel (where it is heated by the nuclear fuel elements) and on through the tubes in a stream generator. (nationalarchives.gov.uk)
  • The submarines reactor is shut down when the vessel is in harbour. (nationalarchives.gov.uk)
  • No one can say for sure, but some experts say that had the accident continued for another 20 to 45 minutes, the [reactor] vessel would have heated up and the metal would have lost its strength, leading to a rupture," preventing further cooling and allowing superheated fuel to melt through the reactor vessel and enter - and likely exit - the reactor building. (whyfiles.org)
  • The second spike led to a reactor vessel rupture and a series of steam explosions. (wikipedia.org)
  • The pebbles are held in a vessel, and an inert gas (such as helium, nitrogen or carbon dioxide) circulates through the spaces between the fuel pebbles to carry heat away from the reactor. (wikipedia.org)
  • In conventional light-water reactor (LWR) designs, the entire fissile core is placed in a large pressure vessel. (wikipedia.org)
  • In most plants, ECCS is composed of the following systems: HPCI consists of a pump or pumps that have sufficient pressure to inject coolant into the reactor vessel while it is pressurized. (wikipedia.org)
  • It is designed to monitor the level of coolant in the reactor vessel and automatically inject coolant when the level drops below a threshold. (wikipedia.org)
  • This system is normally the first line of defense for a reactor since it can be used while the reactor vessel is still highly pressurized. (wikipedia.org)
  • The actuation of these valves depressurizes the reactor vessel and allows lower pressure coolant injection systems to function, which have very large capacities in comparison to high pressure systems. (wikipedia.org)
  • LPCI consists of a pump or pumps that inject coolant into the reactor vessel once it has been depressurized. (wikipedia.org)
  • The Reactor Protection System (RPS) is a system, computerized in later BWR models, that is designed to automatically, rapidly, and completely shut down and make safe the Nuclear Steam Supply System (NSSS - the reactor pressure vessel, pumps, and water/steam piping within the containment) if some event occurs that could result in the reactor entering an unsafe operating condition. (wikipedia.org)
  • graphite
  • Not to nitpick, but Chernobyl wasn't a sodium reactor, it was a graphite moderated, boiling light water cooled reactor. (peachpundit.com)
  • The Calder Hall reactor design was fueled with slugs of natural uranium metal canned in aluminum , was cooled with carbon dioxide , and employed a moderator consisting of a block of graphite pierced by fuel channels. (britannica.com)
  • The applications for carbon are many and include its use as an alloying element with iron in the manufacture of steel, its use as brushes in electrical generators and motors, the use of colloidal graphite or carbon to coat surfaces (e.g. glass), in electrical assemblies to absorb microwaves and inhibit photoelectrons and secondary electrons, and the use of high purity carbon (graphite) in nuclear reactors to moderate neutrons. (goodfellow.com)
  • These events exposed the graphite moderator of the reactor to air, causing it to ignite. (wikipedia.org)
  • Commonly-used moderators include regular (light) water (in 74.8% of the world's reactors), solid graphite (20% of reactors) and heavy water (5% of reactors). (wikipedia.org)
  • The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. (wikipedia.org)
  • The uranium, thorium or plutonium nuclear fuels are in the form of a ceramic (usually oxides or carbides) contained within spherical pebbles a little smaller than the size of a tennis ball and made of pyrolytic graphite, which acts as the primary neutron moderator. (wikipedia.org)
  • Pebble-bed reactors need fire-prevention features to keep the graphite of the pebbles from burning in the presence of air if the reactor wall is breached, although the flammability of the pebbles is disputed. (wikipedia.org)
  • A boiling water reactor, by contrast, has only one coolant loop, while more exotic designs such as breeder reactors use substances other than water for coolant and moderator (e.g. sodium in its liquid state as coolant or graphite as a moderator). (wikipedia.org)
  • 1960s
  • Sodium -cooled fast-neutron-spectrum liquid-metal reactors (LMRs) received much attention during the 1960s and '70s when it appeared that their breeding capabilities would soon be needed to supply fissile material to a rapidly expanding nuclear industry. (britannica.com)
  • The LFTR concept was first investigated at the Oak Ridge National Laboratory Molten-Salt Reactor Experiment in the 1960s, though the MSRE did not use thorium. (wikipedia.org)
  • The concept was first suggested by Farrington Daniels in the 1940s, said to have been inspired by the innovative design of the benghazi burner by British desert troops in WWII, but commercial development did not take place until the 1960s in the German AVR reactor by Rudolf Schulten. (wikipedia.org)
  • rods
  • When the hafnium rods are inserted into the ceramic-based fuel cells, they absorb neutrons so as to stop fisson. (peachpundit.com)
  • It is known that the operation of nuclear reactors to follow a given power program uses neutron-absorbant rods which are moved in the core of the reactor according to the power demand program. (google.com)
  • The enriched fuel is used in the reactors in the form of rods. (hubpages.com)
  • 2. Rods of cadmium are lowered into a reactor to control the reaction. (blogspot.com)
  • The rods regulate the nuclear divisions by absorbing a number of freed neutrons. (blogspot.com)
  • During a disaster, when a power outage happens and diesel power generators which provide emergency power to the water pump are damaged by a tsunami or an earthquake, if no fresh water is being pumped to cool the fuel rods then the fuel rods continue to heat up. (wikipedia.org)
  • Fukushima Daiichi
  • As Japan confronted what Emperor Akihito called the worst crisis since World War II, we began to hear that the six-reactor complex at the Fukushima Daiichi plant, located directly in the tsunami's path, had lost electrical power. (whyfiles.org)
  • turbine
  • The invention relates to a method for regulating the power supplied to a steam turbine by a pressurized water nuclear reactor driving an electrical generator supplying a network. (google.com)
  • The steam is used as a driving fluid for the turbine which actuates the electric current generator. (google.com)
  • The electric power demanded by the network can be variable in the course of time, so that the power that the nuclear reactor must supply to the turbine may itself be essentially variable in the course of time. (google.com)
  • However, in the case of considerable and rapid power variations to respond to the demand of the network, or in the case of electrical disconnection between the power station and the network, this operation being called load-rejection, it is necessary to have an additional regulating means for the power supplied by the steam turbine nuclear reactor. (google.com)
  • In all types the heat extracted from the core by primary sodium is transferred to a secondary, nonradioactive sodium loop, which serves as the heat source for a steam generator that heats the water in a tertiary loop to power a turbine. (britannica.com)
  • The light-water steam exiting the steam generator in the secondary loop is then transported through a conventional turbine cycle. (britannica.com)
  • A power house houses the turbine and the generator. (hubpages.com)
  • The turbine rotates the turbine shaft which in turn rotates the generator shaft, which is coupled to the turbine shaft. (hubpages.com)
  • Thus the turbine converts hydraulic energy into mechanical energy and the generator converts mechanical energy into electrical energy. (hubpages.com)
  • The pressure of the expanding steam turns a turbine that is connected to a generator. (georgiapower.com)
  • Other than the heat source, a nuclear energy facility operates like any fossil fuel plant: 1) heat is created to boil water 2) to create steam 3) to turn the turbine 4) which spins the generator. (georgiapower.com)
  • The steam is used to drive a turbine connected to an electrical generator. (blogspot.com)
  • Boiling water reactors (BWR) do not use steam generators, as turbine steam is produced directly in the reactor core. (wikipedia.org)
  • Activation of oxygen and dissolved nitrogen in the water means that the turbine hall is inaccessible during reactor operation and for some time afterwards. (wikipedia.org)
  • citation needed] In a nuclear power station, the pressurized steam is fed through a steam turbine which drives an electrical generator connected to the electric grid for transmission. (wikipedia.org)
  • The condenser converts the steam to a liquid so that it can be pumped back into the steam generator, and maintains a vacuum at the turbine outlet so that the pressure drop across the turbine, and hence the energy extracted from the steam, is maximized. (wikipedia.org)
  • A heat exchanger, also known as a steam generator, transfers the heat to a secondary cooling loop, which powers a steam turbine with an electric generator attached to it (for a typical Rankine thermodynamic cycle). (wikipedia.org)
  • Boiling
  • Light water reactors, both boiling water and pressurised water reactors the most common type, use ordinary (light) water. (wikipedia.org)
  • The coolant (treated water), which is maintained at high pressure to prevent boiling, is pumped through the nuclear reactor core. (wikipedia.org)
  • for example the boiling water reactor. (wikipedia.org)
  • Play media Pressurized water reactors (PWRs) constitute the large majority of the world's nuclear power plants (notable exceptions being the United Kingdom, Japan, the United States and Canada) and are one of three types of light water reactor (LWR), the other types being boiling water reactors (BWRs) and supercritical water reactors (SCWRs). (wikipedia.org)
  • Boiling water reactor safety systems are nuclear safety systems constructed within boiling water reactors in order to prevent or mitigate environmental and health hazards in the event of accident or natural disaster. (wikipedia.org)
  • Also like the pressurized water reactor, a boiling water reactor has a negative void coefficient, that is, the neutron (and the thermal) output of the reactor decreases as the proportion of steam to liquid water increases inside the reactor. (wikipedia.org)
  • radiation
  • Coal has a trace amount of radioactive carbon (C14, usually absorbed from the environment the coal came from) that generates more measurable radiation than you can detect outside a nuclear power plant. (peachpundit.com)
  • The entire process takes place inside a heavy shielded reactor compartment that completely protects the crew from radiation. (nationalarchives.gov.uk)
  • The nuclear reactor is enclosed in a thick, massive, concrete, shield so as to protect the surrounding from radiation. (hubpages.com)
  • From an energy point of view the gamma-ray energy should not be so low that the radiation gets completely absorbed before emerging from the patient's body and not too high that it is difficult to detect. (wikibooks.org)
  • the enclosure was not intended as a radiation shield, but was built quickly as occupational safety for the crews of the other undamaged reactors at the power station, with No.3 continuing to produce electricity into 2000. (wikipedia.org)
  • Japan's nuclear regulator said one reactor core at the quake-damaged Fukushima Dai-Ichi power plant may be cracked and leaking radiation. (abovetopsecret.com)
  • Acute neutron radiation exposure (e.g., from a nuclear criticality accident) converts some of the stable 23 Na in human blood plasma to 24 Na. (wikipedia.org)
  • Measurements of its quantity are used to determine the absorbed radiation dose of the patient. (wikipedia.org)
  • Shielding: Sources of radiation can be shielded with solid or liquid material, which absorbs the energy of the radiation. (wikipedia.org)
  • The term 'biological shield' is used for absorbing material placed around a nuclear reactor, or other source of radiation, to reduce the radiation to a level safe for humans. (wikipedia.org)
  • power
  • Future reactor designs will use neither of these methods, and many of them will enable the use of off the shelf natural occurring Uranium and Thorium, which will push the viability of nuclear power from 100's to millions or billions of years. (peachpundit.com)
  • American nuclear power plants have several levels of containment that the Soviet reactor didn't have. (peachpundit.com)
  • In pressurized water nuclear power stations used for the generation of electric current, steam is produced by heat exchange between the primary fluid constituted by water under pressure and the secondary fluid constituted by water which is converted into steam inside the steam generators. (google.com)
  • On the other hand, it is sometimes necessary to disconnect the current generator from the network for a longer or shorter time for a reason independent of the operation of the nuclear power station itself. (google.com)
  • Schematic diagram of a nuclear power plant using a pool-type sodium-cooled liquid-metal reactor. (britannica.com)
  • Electric-power generation is obtained through the transfer of the heat of fission into the heavy-water coolant, which is circulated to a steam generator. (britannica.com)
  • Capacity factor refers to the ratio of time that a reactor is operating at full power during a given period versus the total available time during that same period. (britannica.com)
  • Thus, a capacity factor of 1.0 refers to a reactor that operates at full power 24 hours a day over the entire period of time being considered. (britannica.com)
  • The advanced gas-cooled reactor (AGR) was developed in the United Kingdom as the successor to reactors of the Calder Hall class, which combined plutonium production and power generation. (britannica.com)
  • Hydrogen-cooled turbogenerators are currently the most common electrical generators in large power plants. (wikipedia.org)
  • Before the reactor is shut down, electricity from the shore is required to power the submarine's mechanical and electrical systems such as pumps and back up systems. (nationalarchives.gov.uk)
  • During fission, a small amount of mass is converted into energy, which can be used to power a generator to create electricity. (scientificamerican.com)
  • The U.S. constructed two experimental breeder reactors, neither of which produced power commercially. (scientificamerican.com)
  • After an initial agreement between Ronald Reagan and Mikhail Gorbachev in November 1985, the ITER reactor effort developed, and remains the primary international effort to develop practical fusion power. (wikipedia.org)
  • The nuclear powered steam generator started as a power plant for the first nuclear submarine, the USS Nautilus (SSN-571). (wikipedia.org)
  • It was designed and built by the Westinghouse power company for the submarine from there the company started its development and research of nuclear powered steam generators. (wikipedia.org)
  • Once peaceful nuclear reactors were legalized for use as power plants, power corporations jumped at the opportunity to utilize the growing development of nuclear powered steam generators. (wikipedia.org)
  • Westinghouse built one of the first nuclear power plants, the Yankee Rowe nuclear power station (NPS), which also used a nuclear powered steam generator, in 1960. (wikipedia.org)
  • Eventually, other international companies such as Babcock & Wilcox and Combustion Engineering began their own programs for research and development of the nuclear power steam generator. (wikipedia.org)
  • The accident motivated safety upgrades on all remaining Soviet-designed reactors in the RBMK (Chernobyl No.4) family, of which eleven continued to power electric grids as of 2013. (wikipedia.org)
  • Solar electric, due to the low amount of energy per square foot of generator, fairly demands decentralization: rooftops are about the only environmentally neutral surface area available in sufficient quantity to power most cities. (earthisland.org)
  • Nuclear reactors are used at nuclear power plants for electricity generation and in propulsion of ships. (wikipedia.org)
  • As of April 2014, the IAEA reports there are 435 nuclear power reactors in operation, in 31 countries around the world. (wikipedia.org)
  • 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. (wikipedia.org)
  • Nuclear reactors typically employ several methods of neutron control to adjust the reactor's power output. (wikipedia.org)
  • The first purely commercial nuclear power plant at Shippingport Atomic Power Station was originally designed as a pressurized water reactor (although the first power plant connected to the grid was at Calder Hall, UK), on insistence from Admiral Hyman G. Rickover that a viable commercial plant would include none of the "crazy thermodynamic cycles that everyone else wants to build. (wikipedia.org)
  • The United States Army Nuclear Power Program operated pressurized water reactors from 1954 to 1974. (wikipedia.org)
  • The energy lost by the neutrons heats the moderator and is extracted for power. (wikipedia.org)
  • PWRs also use boric acid to make fine adjustments to reactor power level, or reactivity, using their Chemical and Volume Control System (CVCS). (wikipedia.org)
  • It is also used as a thermal power source in radioisotope thermoelectric generator power packs. (wikipedia.org)
  • Thorium reactors can generate power from the plutonium residue left by uranium reactors. (wikipedia.org)
  • The fission process stops when the proton beam stops, as when power is lost, thus the reactor is subcritical. (wikipedia.org)
  • The increased ratio of water to steam will lead to increased neutron moderation, which in turn will cause an increase in the power output of the reactor. (wikipedia.org)
  • In the limiting case of an ATWS (Anticipated Transient Without Scram) derangement, high neutron power levels (~ 200%) can occur for less than a second, after which actuation of SRVs will cause the pressure to rapidly drop off. (wikipedia.org)
  • A few commercial power reactor designs, such as the reaktor bolshoy moshchnosti kanalniy (RBMK) and pressurized heavy water reactor (PHWR), do permit refueling without shutdowns, and they may pose a proliferation risk. (wikipedia.org)
  • kinetic
  • and lithium, being a light element, also converts neutron kinetic energy to thermal energy by means of elastic-scattering reactions. (google.es)
  • fission products
  • The fission products which produce delayed neutrons have half lives for their 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. (wikipedia.org)