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Encyclopedia > Boiling water reactor

A boiling water reactor (BWR) is a generation II light water reactor is a type of nuclear reactor developed by the General Electric Company in the mid 1950s. In contrast to the pressurized water reactor (PWR), in a BWR the steam going to the turbine that powers the electical generator is produced in the reactor core rather than in steam generators or heat exchanger. There is a single circuit in a BWR in which the water is at lower pressure (about 75 times atmospheric pressure)than in a PWR so that it boils in the core at about 285°C. The reactor is designed to operate with 12–15% of the water in the top part of the core as steam, resulting in less moderation, lower neutron efficiency and lower power density than in the bottom part of the core. In comparison, there is no significant boiling allowed in a PWR because of the high pressure maintained in its primary loop (about 158 times atmospheric pressure). A generation II reactor is a nuclear power reactor of one of several types developed from the first generation I reactors. ... A light water reactor or LWR is a thermal nuclear reactor that uses ordinary water (as opposed to heavy water) as its neutron moderator. ... A pressurised water reactor (PWR) is a type of nuclear power reactor that uses ordinary light water for both coolant and for neutron moderation. ... In a gaseous fission reactor the reaction takes place in a core which is bounded and created by magnetic field. ... A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ... This article or section does not cite its references or sources. ... In engineering, specific power (sometimes also power per unit mass or power density) refers to the amount of power delivered by an energy source, divided by some measure of the sources size or mass. ...

Contents



Reactor power is controlled via two methods: by inserting or withdrawing control rods and by changing the water flow through the reactor core.

Positioning (withdrawing or inserting) control rods is the normal method for controlling power when starting up the reactor and operating up to approximately 70% of rated power. As control rods are withdrawn, neutron absorption decreases in the control material and increases in the fuel, so reactor power increases. As control rods are inserted, neutron absorption increases in the control material and decreases in the fuel, so reactor power decreases.
Changing (increasing or decreasing) the flow of water through the core is the normal method for controlling power when operating between approximately 70% and 100% of rated power. As flow of water through the core is increased, steam bubbles ("voids") are more quickly removed from the core, the amount of liquid water in the core increases, neutron moderation increases, more neutrons are slowed down to be absorbed by the fuel, and reactor power increases. 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.

Steam produced in the reactor core passes through steam separators and dryer plates above the core and then directly to the turbine, which is part of the reactor circuit. Because the water around the core of a reactor is always contaminated with traces of radionuclides, the turbine must be shielded during normal operation, and radiological protection must be provided during maintenance. The increased cost related to operation and maintenance of a BWR tends to balance the savings due to the simpler design and greater thermal efficiency of a BWR when compared with a PWR. Most of the radioactivity in the water is very short-lived (mostly N-16, with a 7 second half life), so the turbine hall can be entered soon after the reactor is shut down. Half-Life is a science fiction first-person shooter computer game developed by Valve Software and published by Sierra Studios. ...


Like the pressurized water reactor, the BWR reactor core continues to produce heat from radioactive decay after the fission reactions have stopped, making nuclear meltdown possible in the event that all safety systems have failed and the core does not receive coolant. 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. However, unlike a pressurized water reactor which contains no steam in the reactor core, a sudden increase in BWR steam pressure (caused, for example, by a blockage of steam flow from the reactor) will result in a sudden decrease in the proportion of steam to liquid water inside the reactor. 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. Because of this effect in BWRs, operating components and safety systems are designed to ensure that no credible, postulated failure can cause a pressure and power increase that exceeds the safety systems' capability to quickly shutdown the reactor before damage to the fuel or to components containing the reactor coolant can occur. A pressurised water reactor (PWR) is a type of nuclear power reactor that uses ordinary light water for both coolant and for neutron moderation. ... An induced nuclear fission event. ... A nuclear meltdown occurs when the core of a nuclear reactor ceases to be properly controlled and cooled due to failure of control or safety systems, and begins to overheat and melt. ... In nuclear engineering, the void coefficient (more properly called void coefficient of reactivity) is a number that can be used to estimate how much the thermal output of a nuclear reactor increases (or decreases, if negative) as voids (steam bubbles) form in the reactor moderator or coolant. ...


In the event of an emergency that disables all of the safety systems, each reactor is surrounded by a containment building designed to seal off the reactor from the environment. A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. ...


A modern BWR fuel assembly comprises 74 to 100 fuel rods, and there are up to approximately 800 assemblies in a reactor core, holding up to approximately 140 tonnes of uranium. The number of fuel assemblies in a specific reactor is based on considerations of desired reactor power output, reactor core size and reactor power density.


The current generation of BWRs, in operation in Japan, are called Advanced Boiling Water Reactors (ABWR).


Animated Diagram of a Boiling Water Reactor. ...


Advantages

  • The reactor vessel and associated components operate at a substantially lower pressure (about 75 times atmospheric pressure) compared to a PWR (about 158 times atmospheric pressure).
  • Pressure vessel is subject to significantly less irradiation compared to a PWR, and so does not become as brittle with age.
  • Operates at a lower nuclear fuel temperature.

Disadvantages

  • Complex operational calculations for managing the utilization of the nuclear fuel in the fuel elements during power production due to "two phase fluid flow" (water and steam) in the upper part of the core (less of a factor with modern computers). More incore nuclear instrumentation is required.
  • Much larger pressure vessel than for a PWR of similar power, with correspondingly higher cost. (However, the overall cost is reduced because a modern BWR has no main steam generators and associated piping.)
  • Contamination of the turbine by fission products (less of a factor with modern fuel technology).
  • Shielding and access control around the steam turbine are required during normal operations due to the radiation levels arising from the steam entering directly from the reactor core. Additionally, additional precautions are required during turbine maintenance activities compared to a PWR.
  • Control rods must be inserted from below, and can hence not fall into the reactor under their own weight in case of a total power loss ( in most other reactor types the control rods are suspended from electromagnets, causing them to fall into the reactor if power is lost ).

List of BWRs

U.S. Commercial Boiling Water Reactor Nuclear Power Plants

(this list is believed to be complete)

Big Rock Point was a nuclear power plant in Charlevoix, Michigan. ... Official language(s) None (English, de-facto) Capital Lansing Largest city Detroit Area  Ranked 11th  - Total 97,990 sq mi (253,793 km²)  - Width 239 miles (385 km)  - Length 491 miles (790 km)  - % water 41. ... The Browns Ferry nuclear power plant is located on the Tennessee River near Decatur, Alabama. ... Athens is a city located in Limestone County, Alabama, and is included in the Huntsville-Decatur Metro Area. ... This article or section does not cite its references or sources. ... The Brunswick power plant, named for the county in which it is located, covers 1,200 acres (4. ... This article is the current U.S. Collaboration of the Week. ... The Clinton Power Station and is 5,000-acre cooling reservoir are located on a 14000-acre site near Clinton, Illinois, USA. Clintons final construction cost exceeded $4 billion, leading the plant to produce some of the most expensive power in the Midwest. ... Official language(s) English Capital Springfield Largest city Chicago Area  Ranked 25th  - Total 57,918 sq mi (149,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... The Columbia Nuclear Generating Station, a nuclear power station, is a General Electric boiling water reactor located 12 miles (19 km) NW of Richland, Washington. ... This article does not cite its references or sources. ... Nebraska Public Power Districts Cooper Nuclear Station in Brownville, Nebraska Cooper Nuclear Station (CNS) is a boiling water reactor (BWR) type nuclear power plant located on a 1,251 acre (5. ... Official language(s) English Capital Lincoln Largest city Omaha Area  Ranked 16th  - Total 77,421 sq mi (200,520 km²)  - Width 210 miles (340 km)  - Length 430 miles (690 km)  - % water 0. ... Dresden, Illinois is the USA’s first Nuclear Power Plant ever built. ... Official language(s) English Capital Springfield Largest city Chicago Area  Ranked 25th  - Total 57,918 sq mi (149,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... The Duane Arnold Energy Center is located on a 500 acre (2 km²) site two miles north of Palo, Iowa, or eight miles northwest of Cedar Rapids. ... This article or section does not cite its references or sources. ... Elk River Station is an incinerator operating in Elk River, Minnesota that generates 35 to 42 megawatts of electrical power. ... Capital Saint Paul Largest city Minneapolis Area  Ranked 12th  - Total 87,014 sq mi (225,365 km²)  - Width 250 miles (400 km)  - Length 400 miles (645 km)  - % water 8. ... Named for the first physicist to create a nuclear reactor, the Enrico Fermi plant is located between Detroit, Michigan and Toledo, Ohio in northeastern Monroe County, Michigan The 94MWe prototype fast breeder reactor Fermi 1 unit operated at the site from 1963 to 1972 and is now in the process... Official language(s) None (English, de-facto) Capital Lansing Largest city Detroit Area  Ranked 11th  - Total 97,990 sq mi (253,793 km²)  - Width 239 miles (385 km)  - Length 491 miles (790 km)  - % water 41. ... The James A. Fitzpatrick nuclear power plant is located near Oswego, New York. ... Official language(s) English de facto Capital Albany Largest city New York City Area  Ranked 27th  - Total 54,520 sq mi (141,205 km²)  - Width 285 miles (455 km)  - Length 330 miles (530 km)  - % water 13. ... Grand Gulf nuclear power station is a General Electric boiling water reactor. ... This article does not cite its references or sources. ... The Edwin I. Hatch nuclear power plant is near Baxley, Georgia, on a 2,244 acre (9 km²) site. ... Hope Creek Nuclear is a thermal nuclear power plant located by Hancocks Bridge, New Jersey on the same site as the two unit Salem Nuclear. ... This article does not cite its references or sources. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... The LaSalle County nuclear power station, located 11 miles SE of Ottawa, Illinois serves Chicago and northern Illinois. ... Official language(s) English Capital Springfield Largest city Chicago Area  Ranked 25th  - Total 57,918 sq mi (149,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... The Limerick nuclear power facility in Pennsylvania has two General Electric boiling water reactor (BWR) units, cooled by natural draft cooling towers. ... Official language(s) None Capital Harrisburg Largest city Philadelphia Area  Ranked 33rd  - Total 46,055 sq mi (119,283 km²)  - Width 160 miles (255 km)  - Length 280 miles (455 km)  - % water 2. ... Millstone nuclear power station units 2 and 3 are located at a former quarry in Waterford, Connecticut. ... This article or section does not cite its references or sources. ... The Monticello Nuclear Generating Plant, (a nuclear power plant), is an electricity-generating facility located in Monticello, Minnesota along the Mississippi River. ... Capital Saint Paul Largest city Minneapolis Area  Ranked 12th  - Total 87,014 sq mi (225,365 km²)  - Width 250 miles (400 km)  - Length 400 miles (645 km)  - % water 8. ... Nine Mile Point 1 and 2 are sited near Oswego, New York. ... Official language(s) English de facto Capital Albany Largest city New York City Area  Ranked 27th  - Total 54,520 sq mi (141,205 km²)  - Width 285 miles (455 km)  - Length 330 miles (530 km)  - % water 13. ... Oyster Creek is a single unit thermal boiling water reactor power plant located in Lacey Township, New Jersey. ... This article does not cite its references or sources. ... Peach Bottom NGS, a nuclear power plant, is located 60 miles (97 km) south of Harrisburg in Peach Bottom Township, York County, Pennsylvania, on the Susquehanna River. ... Official language(s) None Capital Harrisburg Largest city Philadelphia Area  Ranked 33rd  - Total 46,055 sq mi (119,283 km²)  - Width 160 miles (255 km)  - Length 280 miles (455 km)  - % water 2. ... The Perry nuclear power plant is a General Electric boiling water reactor located on 1,100 acres (4. ... Official language(s) None Capital Columbus Largest city Columbus Largest metro area Cleveland Area  Ranked 34th  - Total 44,825 sq mi (116,096 km²)  - Width 220 miles (355 km)  - Length 220 miles (355 km)  - % water 8. ... Now the only nuclear power plant operating in Massachusetts, Pilgrim Station is located a few miles down the coast from Plymouth Rock. ... Official language(s) English Capital Boston Largest city Boston Area  Ranked 44th  - Total 10,555 sq mi (27,360 km²)  - Width 183 miles (295 km)  - Length 113 miles (182 km)  - % water 13. ... Quad Cities is a two-unit nuclear power plant located near Cordova, Illinois, USA on the Mississippi River. ... Official language(s) English Capital Springfield Largest city Chicago Area  Ranked 25th  - Total 57,918 sq mi (149,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... River Bend nuclear power station is a General Electric boiling water reactor on a 3,300 acre (13 km²) site in St. ... Official language(s) English and French Capital Baton Rouge Largest city New Orleans at last census; probably Baton Rouge since Hurricane Katrina Area  Ranked 31st  - Total 51,885 sq mi (134,382 km²)  - Width 130 miles (210 km)  - Length 379 miles (610 km)  - % water 16  - Latitude 29°N to 33... The Shoreham Nuclear Power Plant was a General Electric boiling water reactor located in Wading River, Suffolk County, New York, 60 miles east of Manhattan. ... Official language(s) English de facto Capital Albany Largest city New York City Area  Ranked 27th  - Total 54,520 sq mi (141,205 km²)  - Width 285 miles (455 km)  - Length 330 miles (530 km)  - % water 13. ... The Susquehanna Steam Electric Station, a nuclear power station, is in Luzerne County, Pennsylvania just south of Shickshinny. ... Official language(s) None Capital Harrisburg Largest city Philadelphia Area  Ranked 33rd  - Total 46,055 sq mi (119,283 km²)  - Width 160 miles (255 km)  - Length 280 miles (455 km)  - % water 2. ... Vallecitos Nuclear Center (Pleasanton, California) Owner: Pacific Gas and Electric Co. ... Official language(s) English Capital Sacramento Largest city Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 km²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ... Entergys Vermont Yankee Power Plant in Vernon, VT Vermont Yankee is a boiling water reactor (BWR) type nuclear power plant currently owned by Entergy Nuclear. ... Official language(s) None Capital Montpelier Largest city Burlington Area  Ranked 43rd  - Total 9,620 sq mi (24,923 km²)  - Width 80 miles (130 km)  - Length 160 miles (260 km)  - % water 3. ...

Other commercial BWRs

Commercial BWRs outside the USA include:

Elbe estuary Brunsbüttel is a city in northern Germany that lies on the mouth of the Elbe river, near the North Sea. ... The Isar is the third largest river in Bavaria, Germany. ... Lingen is a town in Lower Saxony, Germany. ... Philippsburg is a small town in Germany, in the district of Karlsruhe in Baden-Württemberg. ... These are five different towns with the same name, located in five different states in India. ... Categories: Cities in Aichi Prefecture | Japan geography stubs ... Fukushima may refer to: Fukushima, Fukushima Fukushima Prefecture Fukushima, Hokkaido Fukushima, Matsumae, Hokkaido This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... Omaezaki (御前崎市; -shi) is a city located in Shizuoka, Japan. ... Kashiwazaki (柏崎市; -shi) is a city located in Niigata, Japan. ... Shimane Prefecture (島根県 Shimane-ken) is located in the Chugoku region on Honshu island, Japan. ... Tsuruga (敦賀市; -shi) is a city located in Fukui, Japan. ... Neder-Betuwe (until 2003 called Kesteren) is a municipality in the eastern Netherlands. ... The state of Veracruz de Ignacio de la Llave is one of the 31 states that compose Mexico (does not include the Mexican Federal District). ... Laguna Verde is a Mexican nuclear power plant, located in the municipality of Alto Lucero, Veracruz. ... The Barsebäck nuclear power plant is a closed Swedish nuclear power plant situated in Barsebäck, Kävlinge Municipality, SkÃ¥ne. ... Forsmark Nuclear Power Plant is a nuclear power plant in Sweden, and also the site of the Swedish Final repository for radioactive operational waste. ... Ringhals is a swedish nuclear power plant with 4 reactors. ... Leibstadt is a small town in Switzerland, well known for its nuclear reactor. ... Mühleberg is a municipality in the Laupen administrative district of the canton of Bern, Switzerland. ...

Experimental and other BWRs

Experimental and other non-commercial BWRs include:

  • SL-1 (permanently shut down following accident in 1961)

The SL-1, the Stationary Low-Power Reactor Number One, was a U.S. experimental military nuclear power reactor. ...

Next-generation designs

The Advanced Boiling Water Reactor (ABWR) is an improved design of boiling water reactor. ... 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. ...

See also

List of nuclear reactors is a comprehensive annotated list of all the nuclear reactors of the world, sorted by country. ... The SL-1, the Stationary Low-Power Reactor Number One, was a U.S. experimental military nuclear power reactor. ... A containment building, in its most common usage, is a steel or concrete structure enclosing a nuclear reactor. ... The Nuclear Power 2010 Program was unveiled by the U.S. Secretary of the Department of Energy on February 14, 2002 as one means towards addressing the expected need for new power plants. ...

External links

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  Results from FactBites:
 
boiling water reactor - definition of boiling water reactor in Encyclopedia (696 words)
It has many similarities to the pressurized water reactor, 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.
Types of Nuclear Reactors (282 words)
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.
  More results at FactBites »

 
 

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