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Topic: Pressurized water reactor


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PWR

  
 Pressurized water reactor
The pressurised water reactor (PWR) is the most common type of nuclear reactor, with over 230 in use for power generation and a further several hundred in naval propulsion.
One disadvantage to this type of reactor is that the reactor continues to generate heat from radioactive decay after the fission reaction is stopped, which can result in a nuclear meltdown if the reactor loses all coolant.
A pressured water reactor was involved in the accident at Three Mile Island.
www.ebroadcast.com.au /lookup/encyclopedia/pw/PWR.html   (328 words)

  
 Boiling water reactor - Encyclopedia, History, Geography and Biography   (Site not responding. Last check: 2007-10-20)
It has many similarities to the pressurized water reactor (PWR), except that in a BWR the steam going to the turbine is produced in the reactor core rather than in a steam generator or heat exchanger.
As flow of water through the core is decreased, steam voids remain longer in the core, the amount of liquid water in the core decreases, neutron moderation decreases, fewer neutrons are slowed down to be absorbed by the fuel, and reactor power decreases.
Also like the pressurized water reactor, a boiling-water reactor has a negative void coefficient, that is, the thermal output decreases as the proportion of steam to liquid water increases inside the reactor.
www.arikah.net /encyclopedia/BWR   (939 words)

  
 Light water reactor
The reactor core consisting of fuel and control elements is enclosed by a water-filled steel pressure vessel.
The heat generated by the fission heats the water which evaporates in the pressure vessel in a boiling water reactor but, in the pressurized water reactor, the steam evaporates in a steam generator of a secondary circuit.
The water required to cool the condenser is taken from a river and refed into the river in warmed condition or the heat is dissipated via a cooling tower into the atmosphere.
www.euronuclear.org /info/encyclopedia/l/lightwaterreactor.htm   (194 words)

  
 Pressurized water reactor - Biocrawler   (Site not responding. Last check: 2007-10-20)
Reactor power in most commercial and military PWR's is controlled during normal power operations by varying the concentration of boron (in the form of boric acid) in the primary reactor coolant.
An entire control system involving high pressure pumps (usually called the charging and letdown system) is required to remove water from the high pressure primary loop and re-inject the water back in with differing concentrations of boric acid.
One disadvantage to fission reactors (both PWR and BWR) is that radioactive decay continues to generate significant heat even after the fission reaction stops, possibly leading to nuclear meltdown if the reactor loses all coolant.
www.biocrawler.com /encyclopedia/PWR   (1088 words)

  
 Types of Nuclear Reactors
In the boiling water reactor the same water loop serves as moderator, coolant for the core, and steam source for the turbine.
In the boiling water reactor (BWR), the water which passes over the reactor core to act as moderator and coolant is also the steam source for the turbine.
In the pressurized water reactor (PWR), the water which passes over the reactor core to act as moderator and coolant does not flow to the turbine, but is contained in a pressurized primary loop.
hyperphysics.phy-astr.gsu.edu /hbase/nucene/reactor.html   (282 words)

  
 Pressurized water reactor - Wikipedia, the free encyclopedia
Pressurized water reactors (PWRs) are generation II nuclear power reactors that use water under high pressure as coolant and neutron moderator.
Ordinary water is used as primary coolant in a PWR and flows through the reactor at a temperature of roughly 315 °C ~(600 °F).
PWR reactors are very stable due to their tendency to produce less power as temperatures increase, this helps reduce the chance of losing control of the chain reaction.
en.wikipedia.org /wiki/Pressurized_water_reactor   (1613 words)

  
 Nuclear reactor
In either a boiling-water or pressurized-water installation, steam under high pressure is the medium used to transfer the nuclear reactor's heat energy to a turbine that mechanically turns an electric generator.
The fraction of the reactor's fuel core replaced during refueling is typically one-fourth for a boiling-water reactor and one-third for a pressurized-water reactor.
Additional reactors were used in the navy (United States Naval reactor) In the mid-1950s, both the Soviet Union and western countries were expanding their nuclear research to include non-military uses of the atom.
www.knowledgefun.com /book/n/nu/nuclear_reactor.html   (3465 words)

  
 AEI: June 1996, Pressurized Heavy Water
Water naturally becomes a vapor at temperatures above the normal boiling point of 100 C (212 F) and the only way to force it to remain a liquid is to keep it under pressure.
Sufficient pressure is not too difficult to obtain in a piping system, but it is very challenging to build a tank large enough to hold a critical arrangement of natural uranium in such a way that it is strong enough to withstand that pressure.
The pressure tubes, which are surrounded by a gas filled space and a second tube, contain the fuel bundles along with high pressure, high temperature coolant.
www.atomicinsights.com /jun96/pressure_tube.html   (1141 words)

  
 Pressurized Water reactor (PWR)
PWR is the abbreviation for the Pressurized Water Reactor.
Pressure is maintained at approximately 2250 pounds per square inch through a heater and spray system in the pressurizer.
The water from the Reactor is pumped to the steam generator and passes through tubes.
www.nucleartourist.com /type/pwr.htm   (502 words)

  
 SAFETY PROBLEMS WITH PRESSURIZED WATER REACTORS IN THE UNITED STATES - NIRS
The fundamental characteristic of the PWR is that the primary coolant raises steam in a heat exchanger called a steam generator.
Chronic exposure to extreme radiation, heat, pressure, fatigue, and corrosive chemistry are combining to cause embrittlement of metal, cracking, and erosion of components integral to the protection of the public's health and safety.
A NRC report emphasizes the importance of this component stating "integrity of the reactor pressure vessel is essential in ensuring reactor safety." If the reactor pressure vessel fails, there is no backup system to cool the reactor and avoid an uncontrollable meltdown of the nuclear fuel.
www.nirs.org /factsheets/pwrfact.htm   (891 words)

  
 1995 Water-Use Guidelines: Thermoelectric Power Water Use
The water that does not turn to steam is sent to a second separator where the pressure is further reduced and another portion of it flashes to steam.
Water withdrawal requirements at fossil-fuel and nuclear power generation facilities depend primarily on whether or not the cooling water is recirculated.
The amount of water used by the industry to generate electricity should be reported as a power generation water use, if the data provided from the industrial facility is sufficient to differentiate water used in power generation and the amount of water used for the industrial processes of the plant.
water.usgs.gov /watuse/guidelines/pt.html   (1553 words)

  
 Light Water Nuclear Reactors
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 two varieties of the light water reactor are the pressurized water reactor (PWR) and boiling water reactor (BWR).
hyperphysics.phy-astr.gsu.edu /hbase/nucene/ligwat.html   (452 words)

  
 Aristotel Popescu - Nuclear Power, Pressurized Water Reactor
The first pressurized water reactor, the Mark I prototype for the Nautilus submarine, began operation in May 1953 at the National Reactor Testing Center in Idaho.
By definition, in a pressurized water reactor the fission heat is removed from the fluid elements by the water coolant without bulk boiling occurring.
The extensive use of water as a reactor coolant is related to the relatively low pressure drops accompanying flow at significant rates, and the relatively high heat transfer coefficients.
web.engr.oregonstate.edu /~aristopo/pwr.htm   (374 words)

  
 NS&T : Electricity : Types of Plants : Pressurized Water Reactor
Because the water in the core is under enough pressure to remain a liquid, the reactor is called a pressurized water reactor or PWR for short.
In the first loop pressurized water is pumped through the reactor and then through extremely strong pipes that lead to several steam-generators.
This is because water in the second loop is under less pressure.
www.aboutnuclear.org /view.cgi?fC=Electricity,Types_of_Plants,Pressurized_Water_Reactor   (624 words)

  
 COOLANTS FOR NUCLEAR REACTORS   (Site not responding. Last check: 2007-10-20)
The coolant which passes through the nuclear reactors is used to transport the reactor heat either to a boiler where steam is raised to run a conventional turbine or it is used as a thermodynamic heat engine fluid and passes directly into the turbine and back to the reactor.
Pressure is lower for given steam output conditions than in pressurized water reactor.
Although the reactors mentioned above are classified generally by the type of coolants used, the title heavy water refers to the use of heavy water as a moderator.
www.nuc.berkeley.edu /thyd/ne161/rahmed/coolants.html   (1433 words)

  
 Nuclear Propulsion
For submarines, the reactor compartment is a horizontal cyhder formed by a section of the ship’s pressure hull, with shielded bulkheads on each end.
The submarine thermal reactor prototype was constructed in 1951 and shut down in 1989; the large ship reactor prototype was constructed in 1958 and shut down in 1994; and the submarine reactor plant prototype was constructed in 1965 and shut down in 1995.
The S5G reactor is a prototype pressurized water reactor that operates in either a forced or natural circulation flow mode.
www.fas.org /man/dod-101/sys/ship/eng/reactor.html   (3218 words)

  
 TXU - Pressurized Water
In the plant's containment structure, water under pressure to prevent boiling flows through the reactor.
This hot water gets pumped to the steam generator, or heat exchanger, where the cooler water flowing from the condenser becomes steam.
The condenser converts used steam back into water after it passes over the blades of the turbine, and the water recirculates on the outside of the steam generator tubes.
www.txucorp.com /responsibility/education/generation/water.aspx   (106 words)

  
 Simple Diagram of a Pressurized Water Nuclear Reactor   (Site not responding. Last check: 2007-10-20)
In a Pressurized Water Reactor (PWR), the uranium is located in the core (red).
Heat generated from the "burning" of uranium is transferred to circulating water in the primary loop (blue).
The primary loop is kept at high pressure, so that even though the water temperature is much greater than 100°C, it does not boil.
www.physics.csbsju.edu /RPEG/reactor/reactor.html   (392 words)

  
 Glossary [Photon to Rosenberg Case] | atomicarchive.com
A measure of nuclear blast overpressure or dynamic pressure, used to calculate the effects of a nuclear detonation or the ability of a structure to withstand a nuclear blast.
A reactor in which neutrons heat pressurized water, which is then used to produce steam to run a turbine.
A reactor includes fissionable material (fuel) such as uranium or plutonium, and a moderating material and usually includes a reflector to conserve escaping neutrons, provisions for heat removal, and measuring and control elements.
www.atomicarchive.com /Glossary/Glossary8.shtml   (1096 words)

  
 Nuclear Power Reactors   (Site not responding. Last check: 2007-10-20)
Heat is produced in a nuclear reactor when neutrons strike Uranium atoms causing them to fission in a continuous chain reaction.
In a PWR, the heat is removed from the reactor by water flowing in a closed pressurized loop.
The second loop is kept at a lower pressure, allowing the water to boil and create steam, which is used to turn the turbine-generator and produce electricity.
reactor.engr.wisc.edu /power.html   (433 words)

  
 Pressurized Water Reactor
Water enters from the cold leg nozzles, flows downward in the space between the core barrel and the reactor vessel, then flows upward through holes in the bottom support plate on which the fuel assemblies stand.
The water flows along the fuel assembly, out the top support plate, then into the upper plenum of the reactor.
If the reactor protection system actuates, the power is cut off to control rod drive mechanisms and the CRDMs drop by gravity into the reactor.
www.nucleartourist.com /systems/pwr-rx.htm   (219 words)

  
 WISE NC: NEW GENERATIONS: THE EUROPEAN PRESSURIZED WATER REACTOR
However, this reactor cannot be called one of the long-desired inherently safe reactors; it is seen by the industry as a safer successor of the common Pressurized Water Reactor.
The EPR would be the follow-up of the French N4 reactor (Chooz B1 and B2, Civeaux 1 and 2) and the German Convoy reactor (Emsland and Neckar 2).
The EPR is a pressurized water reactor: water in a cooling circuit under high pressure is heated by the heat from the reactor core.
www.antenna.nl /wise/483-4/4798.html   (1538 words)

  
 Advanced Pressurized Water Reactor - Wikipedia, the free encyclopedia
Advanced Pressurized Water Reactor is a type of nuclear reactor which is an improved version of existing Pressurized Water Reactor types.
In this design the safety systems mainly apply passive protection, which yield such high degree of safety that there is no need for the usual diesel generators, which provide the equipment with power in the case of a loss of electrical supply.
In a standard PWR design, cooling requires elaborate pumps, while in an APWR it can be handled by simple gravity flow with natural convection — cool water enters the bottom of the reactor, which heats it, causing it to rise because warm water is less dense.
en.wikipedia.org /wiki/Advanced_Pressurized_Water_Reactor   (372 words)

  
 Pressurized Water Reactor
One type of nuclear power plant is the pressurized water reactor.
In the containment structure, water under pressure to prevent boiling flows through the reactor where the nuclear chain reaction in the fuel rods heats it to approximately 600 degrees Fahrenheit.
This hot water is pumped to the steam generator, or heat exchanger, where the cooler water flowing in from the condenser becomes steam.
www.mayfieldews.com /pressurized_water_reactor.htm   (132 words)

  
 France's and Europe's Next Pressurized Water Reactor?
In preparation for replacing its current park of nuclear reactors, which in 1999 average about fourteen years in age, EDF has invested in development of a European Pressurized water Reactor, a Franco-German project.
Developers of the EPR view EDF's construction of an initial reactor in the first decade of the 2000s as essential to the continuation of nuclear power in France and also an assurance of nuclear power's future in Europe.
The smaller reactor, they say, would avoid pushing to the limit equipment designed for a reactor of lower power, would make better use of experience gained from the N4 plants, and would better accommodate the needs of possible foreign clients.
www.earthisland.org /yggdrasil/reactor.html   (782 words)

  
 Nuclear and Uranium Survey Forms
The unused steam is exhausted to the condenser where it is condensed into water.
The resulting water is pumped out of the condenser with a series of pumps, reheated, and pumped back to the steam generator.
The reactors core contains fuel assemblies which are cooled by water, which is force-circulated by electrically powered pumps.
www.eia.doe.gov /cneaf/nuclear/page/nuc_reactors/pwr.html   (91 words)

  
 Howstuffworks "How Nuclear Power Works"
The rods can also be lowered completely into the uranium bundle to shut the reactor down in the case of an accident or to change the fuel.
In some reactors, the steam from the reactor goes through a secondary, intermediate heat exchanger to convert another loop of water to steam, which drives the turbine.
Also, in some reactors, the coolant fluid in contact with the reactor core is gas (carbon dioxide) or liquid metal (sodium, potassium); these types of reactors allow the core to be operated at higher temperatures.
www.howstuffworks.com /nuclear-power.htm   (1204 words)

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