Pool-type reactors are a type of nuclear reactor that has a core immersed in an open pool of water. The reactor core, consisting of the fuel elements and the control rods is situated in an open water pool. The water acts as moderator, cooling agent and radiation shield. The layer of water above the reactor core shields the radiation so completely that operators may work above the reactor in total safety. This design has two major advantages: the reactor is easily accessible and the whole primary cooling system, i.e. the pool water, is under normal pressure. This avoids the high temperatures and great pressures of nuclear power plants. Popularly called a "swimming pool reactor", they are used as a source of neutrons and training, in rare instances for process heat but not for electrical generation. Life boats and life savers are often located around the facility to rescue personnel that may fall into the pool, adding further to the appearance of a pool-like environment. 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). ... Moderator can refer to one of the following: neutron moderator moderator (communications) - Message Board Moderator The chairperson of a church court in Presbyterian churches (see Moderator of the General Assembly). ... A nuclear power plant in Cattenom, France. ...

Description

Open pools range in height from 20' to 30' and diameter from 6' to 12'. Some pools are rectangular like the Canadian MAPLE reactor, instead of cylindrical and these are often much larger, containing as much as 110,000 gallons of water. Most pools are built above floor level but some are all or partially below ground. Light water and heavy water only types exist as well as so called tank in pool designs that use heavy water moderation in a small tank situated in a larger light water pool for cooling. Species with pages written Acer campestre - Field Maple Acer grandidentatum - Bigtooth Maple Acer griseum - Paperbark Maple Acer macrophyllum - Bigleaf Maple Acer micranthum - Komine Maple Acer negundo - Manitoba Maple Acer nigrum - Black Maple Acer palmatum - Japanese Maple Acer pensylvanicum - Striped Maple Acer platanoides - Norway Maple Acer pseudoplatanus - Sycamore Maple Acer rubrum... 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. ... In speaking of nuclear reactors, light water is ordinary water. ...

Normally the reactor is charged LEU fuel consisting of less than 20% U-235 alloyed with a matrix such as aluminium or zirconium. HEU was the fuel of choice since it had a longer lifetime, but these have been largely phased out of non-military reactors to avoid proliferation issues. However most often 19.75% enrichment is used, falling just under the threshold. Fuel elements may be plates or rods with 8.5 to 45 wt% uranium. Beryllium and graphite blocks or plates may be added to the core as neutron reflectors and neutron absorbing rods pierce the core for control. General Atomics of La Jolla, CA manufactures TRIGA® reactor fuel elements in France for the majority of these types of reactors around the world. Core cooling is accomplished either by convection induced by the hot core or in larger reactors by forced coolant flow and heat exchangers. Leu (plural: lei) is the name shared by the currencies of Romania and Moldova. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Atomic mass 91. ... Enriched uranium is uranium whose uranium-235 content has been increased through the process of isotope separation. ... The word proliferation can refer to: Nuclear proliferation Chemical weapon proliferation the spread in use of other weapons systems Cell proliferation According to Gloria Anzaldúa (1990), the difference between appropriation and proliferation is that the first steals and harms; the second helps heal breaches of knowledge. ... Enriched uranium is uranium whose uranium-235 content has been increased through the process of isotope separation. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery gray metallic Atomic mass 238. ... General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ... 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 Atomics is a nuclear physics and defense contractor in southern California. ... One of the beaches at La Jolla Cove. ... Convection is the transfer of heat by the motion of or within a fluid. ... A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ...

Various stations for holding items to be irradiated are located inside the core or directly adjacent to the core. Samples may lowered into the core from above or delivered pneumatically via horizontal tubes from outside the tank at core level. Evacuated, or helium filled horizontal tubes may also be installed to direct a beam of neutrons to targets situated at a distance from the reactor hall. General Name, Symbol, Number helium, He, 2 Chemical series noble gases Group, Period, Block 18, 1, s Appearance colorless Atomic mass 4. ...

Applications

Most Research reactors are of the pool type. Typical are the Argonaut class reactors built to teach nuclear reactor theory, nuclear physics and for use in engineering laboratory experiments. These tend to be low power, low maintenance designs. For example AECL's SLOWPOKE is licensed to run unattended for up to 18 hours. Larger examples like the NRU are used for isotope production for medical or industrial use. It was one of these, the CIRUS that was used to produce plutonium for India's 1974 Pokhran-I nuclear device. Other tasks like non-destructive testing and imaging of high density materials or radiobiology services like Boron Neutron Capture Therapy (BNCT) use neutrons from this class of reactor. Research reactors comprise a wide range of civil and commercial nuclear reactors which are generally not used for power generation. ... AECL Initialism Advanced Electronics Company Limited Association for the Elimination of Child Labour Atomic Energy of Canada Limited Australian Egg Corporation Limited This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Slowpoke (ヤドン/Yadon in Japanese, Flegmon in German and Ramoloss in French) is a fictional character in the Pokémon franchise. ... Isotopes are forms of an element whose nuclei have the same atomic number–-the number of protons in the nucleus--but different atomic masses because they contain different numbers of neutrons. ... CIRUS (Canadian-Indian-U.S.) reactor. ... 1974 is a common year starting on Tuesday (click on link for calendar). ... In nondestructive testing, tests are carried out in such a way as to not disturb the specimen’s structural or surface integrity. ... Radiobiology is the study of the response of biological tissues to ionizing radiation. ...

See also

• Pressurized water reactor
• CANDU reactor
• NRX