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Encyclopedia > Light water reactor

A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water, also called light water, as its neutron moderator. This differentiates it from a heavy water reactor, which uses heavy water as a neutron moderator. In practice all LWRs are also water cooled. While ordinary water has some heavy water molecules in it, it is not enough to be important in most applications. Core of a small nuclear reactor used for research. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Light water, in the terminology of nuclear reactors, is ordinary water. ... This does not adequately cite its references or sources. ... Heavy water reactors use heavy water as a neutron moderator. ... Heavy water is dideuterium oxide, or D2O or 2H2O. It is chemically the same as normal water, H2O, but the hydrogen atoms are of the heavy isotope deuterium, in which the nucleus contains a neutron in addition to the proton found in the nucleus of any hydrogen atom. ...


The most common LWRs are pressurized water reactors and boiling water reactors. Pressurized water reactors (PWRs) (also VVER) are generation II nuclear power reactors that use water under high pressure as coolant and neutron moderator. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...


The Russian abbreviation for LWR is VVR (or sometimes WWR), meaning water water reactor. Similarly, the Russian term for a PWR is VVER, meaning water water energy reactor. A pressurized water reactor (PWR) is a type of nuclear power reactor that uses ordinary (light) water for both coolant and for neutron moderator. ... WWER-10ff (also VVER-1000 as a direct translitteration from Russian ВВЭР-1000). ...


Many other reactors are also (light) water cooled, notably the RBMK and some military plutonium production reactors. These are not regarded as LWRs, as they are moderated by graphite, and as a result their nuclear characteristics are very different. RBMK is an acronym for the Russian reaktor bolshoy moshchnosti kanalniy (Russian: Реактор Большой Мощности Канальный) which means reactor (of) high power (of the) channel (type), and describes a now obsolete class of graphite-moderated nuclear power reactor which was built only in the Soviet Union. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight (244) g·mol−1 Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ... Graphite (named by Abraham Gottlob Werner in 1789 from the Greek γραφειν (graphein): to draw/write, for its use in pencils) is one of the allotropes of carbon. ...


The light-water reactor uses uranium 235 as a fuel, enriched to approximately 3 percent. Although this is its major fuel, the uranium 238 atoms also contribute to the fission process by converting to plutonium 239 — about one-half of which is consumed in the reactor. Light-water reactors are generally refueled every 12 to 18 months, at which time, about 25 percent of the fuel is replaced. General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... General Name, Symbol, Number plutonium, Pu, 94 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery white Standard atomic weight (244) g·mol−1 Electron configuration [Rn] 5f6 7s2 Electrons per shell 2, 8, 18, 32, 24, 8, 2 Physical properties Phase solid Density (near r. ...


Light water reactors tend to be simpler and cheaper to build than heavy water reactors. Power-generating capabilities are comparable.

 Light water reactors are the type used by the U.S. military in its Naval nuclear powered vessels. This is so due to the inherent safety of these type reactors. Since light water is used as both a coolant and a moderator in these reactors, if one of these reactors suffers damage due to attack, and thereby compromise of the reactor core's integrity, the ensuing release of this light water acts to shut down the reactor. This is due to its moderator function. Moderators help to encourage the nuclear mass to achieve fission by reflecting some amount of the neutrons back into the core, as opposed to escaping into the surrounding material. When this reflection is removed, the light water reactors used in military applications shut down naturally, as the relective properties of the light water are used as an engineering component to achieve criticality. Removing the light water makes it impossible for the reactor to remain critical, thus leading to shutdown of the nuclear reaction. 

Currently-offered LWRs include the ABWR, AP1000, ESBWR, European Pressurized Reactor, VVER and SWR-1000. The Advanced Boiling Water Reactor (ABWR) is an improved design of boiling water reactor. ... The AP1000 is a proposed passively safe pressurized water reactor designed and manufactured by Westinghouse Electric Company for nuclear power plants. ... The Economic Simplified Boiling Water Reactor (ESBWR) is a generation III+ reactor which builds on the success of the ABWR. Both are designs by General Electric, and are based on their BWR design. ... European Pressurized Reactor (EPR) is a new fission nuclear reactor design, based on the pressurized water reactor or PWR. It has been designed and developed mainly by the Commissariat à lÉnergie Atomique in France and the Karlsruhe Research Center in Germany. ... WWER-10ff (also VVER-1000 as a direct translitteration from Russian ВВЭР-1000). ...


See also


  Results from FactBites:
 
Light Water Nuclear Reactors (452 words)
The nuclear fission reactors used in the United States for electric power production are classified as "light water reactors" in contrast to the "heavy water reactors" used in Canada.
Light water (ordinary water) is used as the moderator in U.S. reactors as well as the cooling agent and the means by which heat is removed to produce steam for turning the turbines of the electric generators.
The use of ordinary water makes it necessary to do a certain amount of enrichment of the uranium fuel before the necessary criticality of the reactor can be maintained.
  More results at FactBites »

 
 

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