Editing Nuclear power (section)

== Power plants ==
[[File:PWR nuclear power plant animation.webm|thumb|thumbtime=2|An animation of a [[pressurized water reactor]] in operation]]
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|caption=Number of electricity-generating civilian reactors by type as of 2014<ref name="IAEA_reactors_stats">{{cite web|title=Nuclear Power Reactors in the World – 2015 Edition|url=http://www-pub.iaea.org/MTCD/Publications/PDF/rds2-35web-85937611.pdf|publisher=International Atomic Energy Agency (IAEA)|access-date=26 October 2017|archive-date=16 November 2020|archive-url=https://web.archive.org/web/20201116191727/https://www-pub.iaea.org/MTCD/Publications/PDF/rds2-35web-85937611.pdf|url-status=live}}</ref>
{{columns-list|colwidth=4em|{{legend inline|#1f77b4|[[Pressurized water reactor|PWR]]}} {{legend inline|#ff7f0e|[[Boiling water reactor|BWR]]}} {{legend inline|#2ca02c|[[Gas-cooled reactor|GCR]]}} {{legend inline|#d62728|[[Pressurized heavy-water reactor|PHWR]]}} {{legend inline|#9467bd|[[Light water graphite-moderated reactor|LWGR]]}} {{legend inline|#8c564b|[[Fast breeder reactor|FBR]]}}}}
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{{Main|Nuclear power plant|Nuclear reactor}}
{{See also|List of commercial nuclear reactors|List of nuclear power stations}}
Nuclear power plants are [[thermal power station]]s that generate electricity by harnessing the [[thermal energy]] released from [[nuclear fission]]. A fission nuclear power plant is generally composed of: a [[nuclear reactor]], in which the nuclear reactions generating heat take place; a cooling system, which removes the heat from inside the reactor; a [[steam turbine]], which transforms the heat into [[mechanical energy]]; an [[electric generator]], which transforms the mechanical energy into electrical energy.<ref name=WNAnuclearreactorbasics />

When a [[neutron]] hits the nucleus of a [[uranium-235]] or [[plutonium]] atom, it can split the nucleus into two smaller nuclei, which is a nuclear fission reaction. The reaction releases energy and neutrons. The released neutrons can hit other uranium or plutonium nuclei, causing new fission reactions, which release more energy and more neutrons. This is called a [[Nuclear chain reaction|chain reaction]]. In most commercial reactors, the reaction rate is contained by [[control rod]]s that absorb excess neutrons. The controllability of nuclear reactors depends on the fact that a small fraction of neutrons resulting from fission are [[Delayed neutron|delayed]]. The time delay between the fission and the release of the neutrons slows changes in reaction rates and gives time for moving the control rods to adjust the reaction rate.<ref name=WNAnuclearreactorbasics>{{cite web |title=How does a nuclear reactor make electricity? |publisher=World Nuclear Association |url=http://www.world-nuclear.org/nuclear-basics/how-does-a-nuclear-reactor-make-electricity.aspx |website=www.world-nuclear.org |access-date=24 August 2018 |archivedate=24 August 2018 |archiveurl=https://web.archive.org/web/20180824134906/http://www.world-nuclear.org/nuclear-basics/how-does-a-nuclear-reactor-make-electricity.aspx |url-status=deviated }}</ref><ref>{{Cite news|url=https://www.scientificamerican.com/article/atomic-age-began-75-years-ago-with-the-first-controlled-nuclear-chain-reaction/|title=Atomic age began 75 years ago with the first controlled nuclear chain reaction|last1=Spyrou|first1=Artemis|date=2017-12-03|work=Scientific American|access-date=2018-11-18|last2=Mittig|first2=Wolfgang|archive-date=2018-11-18|archive-url=https://web.archive.org/web/20181118205736/https://www.scientificamerican.com/article/atomic-age-began-75-years-ago-with-the-first-controlled-nuclear-chain-reaction/|url-status=live}}</ref>