Steam generator (nuclear power)

Steam generator (nuclear power)

:"This is an article about nuclear power plant equipment. For other uses, see steam generator."Steam generators are heat exchangers used to convert water into steam from heat produced in a nuclear reactor core. They are used in pressurized water reactors between the primary and secondary coolant loops.

In commercial power plants steam generators can measure up to 70 feet in height and weigh as much as 800 tons. Each steam generator can contain anywhere from 3,000 to 16,000 tubes, each about three-quarters of an inch in diameter. The coolant is pumped, at high pressure to prevent boiling, from the reactor coolant pump, through the nuclear reactor core, and through the tube side of the steam generators before returning to the pump. This is referred to as the primary loop. That water flowing through the steam generator boils water on the shell side to produce steam in the secondary loop that is delivered to the turbines to make electricity. The steam is subsequently condensed via cooled water from the tertiary loop and returned to the steam generator to be heated once again. The tertiary cooling water may be recirculated to cooling towers where it sheds waste heat before returning to condense more steam. Once through tertiary cooling may otherwise be provided by a river, lake, ocean. This primary, secondary, tertiary cooling scheme is the most common way to extract usable energy from a controlled nuclear reaction.

These loops also have an important safety role because they constitute one of the primary barriers between the radioactive and non-radioactive sides of the plant as the primary coolant becomes radioactive from its exposure to the core. For this reason, the integrity of the tubing is essential in minimizing the leakage of water between the two sides of the plant. There is the potential that if a tube bursts while a plant is operating; contaminated steam could escape directly to the secondary cooling loop. Thus during scheduled maintenance outages or shutdowns, some or all of the steam generator tubes are inspected by eddy-current testing.

In other types of reactors, such as the pressurised heavy water reactors of the CANDU design, the primary fluid is heavy water. Liquid metal cooled reactors such as the in Russian BN-600 reactor also use heat exchangers between primary metal coolant and at the secondary water coolant.

Boiling water reactors do not use steam generators, as steam is produced in the pressure vessel.

Types

Westinghouse and Combustion Engineering designs have vertical U-tubes with inverted tubes for the primary water. Canadian, Japanese, French, and German PWR suppliers use the vertical configuration as well. Russian VVER reactor designs use horizontal steam generators, which have the tubes mounted horizontally. Babcock and Wilcox plants (e.g., Three Mile Island) have smaller steam generators that force water through the top of the OTSGs (once-through steam generators; counter-flow to the feedwater) and out the bottom to be recirculated by the reactor coolant pumps. The horizontal design has proven to be less susceptible to degradation than the vertical U-tube design.

Tube material

Various high-performance alloys and superalloys have been used for steam generator tubing, including type 316 stainless steel, Alloy 400, Alloy 600MA (mill annealed), Alloy 600TT (thermally treated), Alloy 690TT, and Alloy 800Mod.

See also

*Nuclear power plant
*Power station
*Steam shower
*Steam turbine


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Steam generator — A steam generator is a device used to boil water to create steam. It may refer to:*Boiler (steam generator), a closed vessel in which water is heated under pressure *Steam generator (nuclear power), a heat exchanger in a pressurized water reactor …   Wikipedia

  • Boiler (steam generator) — Contents 1 Steam generator (component of prime mover) 2 Boiler types 2.1 Haycock and wagon top boilers …   Wikipedia

  • Nuclear power plant — This article is about electricity generation from nuclear power. For the general topic of nuclear power, see Nuclear power. A nuclear power station. The nuclear reactor is contained inside the cylindrical containment buildings to the right left… …   Wikipedia

  • Nuclear power accidents by country — The abandoned city of Pripyat, Ukraine with the Chernobyl nuclear power plant in the distance. 57 accidents have occurred since the Chernobyl disaster in 1986. Two thirds of these mishaps occurred in the US.[1] The French Atomic Energy Agency… …   Wikipedia

  • Nuclear power — Atomic Power redirects here. For the film, see Atomic Power (film). This article is about the power source. For nation states that are nuclear powers, see List of states with nuclear weapons …   Wikipedia

  • Nuclear power in the United States — For a comprehensive list of U.S. plants, see List of nuclear reactors. NRC regions and locations of nuclear reactors, 2008 Main article: Nuclear power As of 2008, nuclear power in the United States is provided by 104 commercial reactors (69 …   Wikipedia

  • Nuclear power debate — For nuclear energy policies by nation, see Nuclear energy policy. For public protests about nuclear power, see Anti nuclear movement. Three of the reactors at Fukushima I overheated, causing meltdowns that eventually led to hydrogen explosions,… …   Wikipedia

  • Beznau Nuclear Power Plant — Infobox Nuclear power plant name = Beznau Nuclear Power Plant caption = Beznau Nuclear Power Plant country = Switzerland location = Döttingen (AG) coords = coord|47.552107|N|8.228492|E|display=inline owner = operator = Nordostschweizerische… …   Wikipedia

  • Calvert Cliffs Nuclear Power Plant — Infobox NPP Picture=Calvert Cliffs.jpg pic des=Calvert Cliffs NPP Picture des= Status=O Utility=Constellation Energy Location=Lusby, Maryland Supplier=Combustion Engineering Type=PWR Generators=Unit 1: General Electric Unit 2: Westinghouse… …   Wikipedia

  • Paks Nuclear Power Plant — Infobox NPP Picture = Pic des = Country = Hungary location = Paks owner = Magyar Villamos Művek Zrt. operator = Paksi Atomerőmű Zrt. Built = 1967ndash 1987 Start = December 28, 1982 End = r type = VVER 440/V213 r active = 4 r active mw = 1,866… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”