Nuclear reactor - Revision history

Jmdonev: 1 revision imported

2021-10-18T16:14:40Z

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energy>Luisa at 15:31, 16 October 2021

2021-10-16T15:31:03Z

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	[[Category:Done 2018-06-15]]		[[Category:Done 2018-06-15]]
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			[[es:Reactor nuclear]]
	[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]		[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]

Jmdonev: 1 revision imported

2018-06-25T14:30:34Z

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Jmdonev at 22:12, 21 June 2018

2018-06-21T22:12:57Z

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	[[category:371 topics]]		[[category:371 topics]]
	[[Category:Done ~~2017~~-12-31]]		[[Category:Done 2018-06-15]]
	[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]		[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]

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	<center><html>		<center><html>
	<iframe scrolling='no' src='~~http~~://energyeducation.ca/simulations/nuclear/fission.html~~' style='overflow:visible;max-width:525px;width:600px;height:525px;border:none~~'></iframe>		<iframe id='fission' scrolling='no'src='https://energyeducation.ca/simulations/nuclear/fission.html'>
			</iframe>
	</html></center>		</html></center>

	===Coolant===		===Coolant===

Jmdonev: 1 revision imported

2018-04-14T21:17:36Z

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Jmdonev at 04:07, 12 January 2018

2018-01-12T04:07:28Z

← Older revision		Revision as of 04:07, 12 January 2018
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	[[category:371 topics]]		[[category:371 topics]]
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	[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]		[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]

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	===Moderator===		===Moderator===
	~~<html>~~
	<iframe id='moderation' scrolling='no' src='http://energyeducation.ca/simulations/nuclear/fission.html' style='overflow:visible;max-width:525px;width:600px;height:525px;border:1 px solid black'></iframe>
	~~</html>~~
	:''[[neutron moderator\|main article]]''		:''[[neutron moderator\|main article]]''

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	Most reactors use [[light water]] as a moderator, such as [[pressurized water reactor]]s and [[boiling water reactor]]s. [[Carbon]] works similarly and is used in reactors such as the [[RBMK]]. A third type of moderator used in [[CANDU reactor]]s is [[heavy water]], which is water composed of heavy hydrogen, called [[deuterium]], rather than normal [[hydrogen]].		Most reactors use [[light water]] as a moderator, such as [[pressurized water reactor]]s and [[boiling water reactor]]s. [[Carbon]] works similarly and is used in reactors such as the [[RBMK]]. A third type of moderator used in [[CANDU reactor]]s is [[heavy water]], which is water composed of heavy hydrogen, called [[deuterium]], rather than normal [[hydrogen]].

	The simulation ~~to the right~~ should help in visualizing how a moderator does its job: neutrons that are going too fast are absorbed by uranium-238 and do not yield fission (green) and the moderated neutrons are absorbed by uranium-235 which splits into smaller atoms and produces excess neutrons to continue the reaction (red).		The simulation below should help in visualizing how a moderator does its job: neutrons that are going too fast are absorbed by uranium-238 and do not yield fission (green) and the moderated neutrons are absorbed by uranium-235 which splits into smaller atoms and produces excess neutrons to continue the reaction (red).

			<center><html>
			<iframe scrolling='no' src='http://energyeducation.ca/simulations/nuclear/fission.html' style='overflow:visible;max-width:525px;width:600px;height:525px;border:none'></iframe>
			</html></center>

	===Coolant===		===Coolant===

J.williams: 1 revision imported

2015-09-18T16:51:23Z

1 revision imported

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Jhanania at 20:44, 3 September 2015

2015-09-03T20:44:49Z

← Older revision		Revision as of 20:44, 3 September 2015
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	[[category:371 topics]]		[[category:371 topics]]
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	[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]		[[File:Advanced_Test_Reactor.jpg\|220px\|thumb\|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]

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	:''[[uranium enrichment\|main article]]''		:''[[uranium enrichment\|main article]]''

	Not all nuclei of a given [[element]] are built exactly the same. An element is defined by the number of [[proton]]s within the nucleus, and varying numbers of [[neutron]]s in the nucleus can cause it to behave differently. [[Uranium\|Natural uranium]] is mostly made up of uranium-238 (99.3%), with uranium-235 (0.7%) and very small amount of uranium-234 (0.0055%).<ref>European Nuclear Society. (June 25 2015). ''Natural uranium'' [Online], Available: https://www.euronuclear.org/info/encyclopedia/n/naturaluranium.htm</ref> Most reactors require a higher percentage of uranium-235 in order to sustain nuclear fission reactions, which can be done through [[uranium enrichment]] processes.		Not all nuclei of a given [[element]] are built exactly the same. An element is defined by the number of [[proton]]s within the [[nucleus]], and varying numbers of [[neutron]]s in the nucleus can cause it to behave differently. [[Uranium\|Natural uranium]] is mostly made up of uranium-238 (99.3%), with uranium-235 (0.7%) and very small amount of uranium-234 (0.0055%).<ref>European Nuclear Society. (June 25 2015). ''Natural uranium'' [Online], Available: https://www.euronuclear.org/info/encyclopedia/n/naturaluranium.htm</ref> Most reactors require a higher percentage of uranium-235 in order to sustain nuclear fission reactions, which can be done through [[uranium enrichment]] processes.

	===Moderator===		===Moderator===
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	Moderators are used to slow down the neutrons produced from fission. This is necessary because many nuclear fuels (uranium-235, for instance) require neutrons to be slow-moving in order to absorb them. Nuclei with low mass numbers are most effective at doing so, therefore materials like [[water]] or [[graphite]] are often used.<ref name=ine>J.R. Lamarsh and A.J. Baratta, "Components of Nuclear Reactors" in ''Introduction to Nuclear Engineering'', 3rd ed., Upper Saddle River, NJ: Prentice Hall, 2001, ch.4, sec.4, pp. 133-136</ref>		Moderators are used to slow down the neutrons produced from fission. This is necessary because many nuclear fuels (uranium-235, for instance) require neutrons to be slow-moving in order to absorb them. Nuclei with low mass numbers are most effective at doing so, therefore materials like [[water]] or [[graphite]] are often used.<ref name=ine>J.R. Lamarsh and A.J. Baratta, "Components of Nuclear Reactors" in ''Introduction to Nuclear Engineering'', 3rd ed., Upper Saddle River, NJ: Prentice Hall, 2001, ch.4, sec.4, pp. 133-136</ref>

	Most reactors use [[light water]] as a moderator, such as [[pressurized water reactor]]s and [[boiling water reactor]]s. Carbon works similarly and is used in reactors such as the [[RBMK]]. A third type of moderator used in [[CANDU reactor]]s is [[heavy water]], which is water composed of heavy hydrogen rather than normal hydrogen.		Most reactors use [[light water]] as a moderator, such as [[pressurized water reactor]]s and [[boiling water reactor]]s. [[Carbon]] works similarly and is used in reactors such as the [[RBMK]]. A third type of moderator used in [[CANDU reactor]]s is [[heavy water]], which is water composed of heavy hydrogen, called [[deuterium]], rather than normal [[hydrogen]].

	The simulation to the right should help in visualizing how a moderator does its job: neutrons that are going too fast are absorbed by uranium-238 and do not yield fission (green) and the moderated neutrons are absorbed by uranium-235 which splits into smaller atoms and produces excess neutrons to continue the reaction (red).		The simulation to the right should help in visualizing how a moderator does its job: neutrons that are going too fast are absorbed by uranium-238 and do not yield fission (green) and the moderated neutrons are absorbed by uranium-235 which splits into smaller atoms and produces excess neutrons to continue the reaction (red).
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	===Economics===		===Economics===
	The building of nuclear reactors is economically intensive. The initial capital costs are high compared to fossil fuel plants with similar output. Nuclear power requires a high amount of additional safety, and is completely responsible for all possible waste. What makes nuclear power economically feasible is the large amount of energy that comes from a small volume of fuel. This relationship is known as [[energy density]], and provides a cost advantage to using nuclear fuels. The cost of fuel is relatively lower for a nuclear power plant compared to fossil fuels. This is what makes nuclear reactors competitive despite high initial capital costs.		The building of nuclear reactors is economically intensive. The initial capital costs are high compared to [[fossil fuel]] plants with similar output. [[Nuclear power]] requires a high amount of additional safety, and is completely responsible for all possible [[nuclear waste]]. What makes nuclear power economically feasible is the large amount of [[energy]] that comes from a small [[volume]] of fuel. This relationship is known as [[energy density]], and provides a cost advantage to using nuclear fuels. The cost of [[fuel]] is relatively lower for a nuclear [[power plant]] compared to fossil fuels. This is what makes nuclear reactors competitive despite high initial capital costs.

	===Reactor types===		===Reactor types===

J.williams: 1 revision imported

2015-08-26T21:31:26Z

1 revision imported

← Older revision	Revision as of 21:31, 26 August 2015
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J.williams at 16:57, 12 August 2015

2015-08-12T16:57:11Z

New page

[[category:371 topics]]
[[Category:Done 2015-07-24]]
[[File:Advanced_Test_Reactor.jpg|220px|thumb|Figure 1. The core of a nuclear [[research reactor]].<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/f/f2/Advanced_Test_Reactor.jpg</ref>]]

<onlyinclude>A '''nuclear reactor''' is a system used to initiate and contain a [[nuclear chain reaction]], and they have many useful applications. These nuclear reactions produce [[thermal energy]] through either [[nuclear fission]] (in practice) or [[nuclear fusion]] (in development).</onlyinclude> Nuclear reactors are primarily used for the [[electrical generation|generation of electricity]], however they can be used for propulsion in vehicles such as [[submarine propulsion|submarines]] or naval vessels, for production of useful [[isotope]]s or [[neutron]]s, and for research and training.<ref name=wna>World Nuclear Association. (July 2, 2015). ''Nuclear Reactors'' [Online], Available: http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Power-Reactors/Nuclear-Power-Reactors/</ref><ref name=win>What is nuclear?. (July 2, 2015). ''What is a nuclear reactor?'' [Online], Available: http://www.whatisnuclear.com/articles/nucreactor.html</ref>

Nuclear reactors can be found all over the world. Used in [[nuclear power plant]]s, fission reactors contribute about 11% of the world's total electricity.<ref>IEA (2014), "World energy balances", IEA World Energy Statistics and Balances (database). DOI: http://dx.doi.org/10.1787/data-00512-en (Accessed February 2015)</ref> Although there are many different designs for fission reactors, most consist of the same components for their operation. The difference between each type of fission reactor comes from the different approaches used to satisfy these requirements.

For this article, nuclear fission will be primarily discussed due to its current use around the world. If you would like to read about nuclear fusion, please visit its page [[nuclear fusion|here]].

==How do they work?==

The basic operating principles of a nuclear reactor for the production of power are as follows: Nuclear chain reactions within the reactor produce [[heat]], which is transferred to a coolant (most commonly [[light water]]), the coolant either boils to [[steam]] directly or heats another loop of water into steam, it then passes through a [[turbine]] which spins a [[generator]], and produces [[electricity]].<ref name=wna/> Although the basic principles appear simple, the process is fairly complex.

===Fuel===
:''[[nuclear fuel|main article]]''

Nuclear reactors require the use of [[nuclear fuel]]s, elements that can be readily altered and will release thermal energy. [[Uranium]] is the most common element used as a nuclear fuel, although [[thorium]] is also possible. The naturally occurring [[isotope]]s are found in countries such as Kazakhstan, Canada and Australia.<ref>World Nuclear Association. (July 2, 2015). ''Uranium Mining'' [Online], Available: http://www.world-nuclear.org/info/Nuclear-Fuel-Cycle/Mining-of-Uranium/World-Uranium-Mining-Production/</ref>

The uranium fuel is manufactured into small [[fuel pellet]]s and are packed into [[fuel rod]]s and surrounded by [[cladding]] to avoid leaking into the [[coolant]]. These fuel rods are assembled into a [[fuel bundle]], as seen below. There can be hundreds of fuel bundles in a nuclear reactor, meaning there can be tens of thousands of fuel rods.<ref name=win/>

<gallery caption="Nuclear fuel" mode=packed heights=180px>
File:fuel rod.png|Fuel rods are surrounded by coolant to avoid overheating.<ref>Made internally by a member of the Energy Education team. Adapted from What is nuclear?'s Nuclear reactor page, Available: http://www.whatisnuclear.com/articles/nucreactor.html</ref>
File:Nuclear fuel element.jpg|These assemblies are used in boiling and pressurized water reactors, and are packed into the core to produce heat in a nuclear reaction.<ref>Wikimedia Commons [Online], Available: https://upload.wikimedia.org/wikipedia/commons/2/2d/Nuclear_fuel_element.jpg</ref>
</gallery>

====Fuel enrichment====
:''[[uranium enrichment|main article]]''

Not all nuclei of a given [[element]] are built exactly the same. An element is defined by the number of [[proton]]s within the nucleus, and varying numbers of [[neutron]]s in the nucleus can cause it to behave differently. [[Uranium|Natural uranium]] is mostly made up of uranium-238 (99.3%), with uranium-235 (0.7%) and very small amount of uranium-234 (0.0055%).<ref>European Nuclear Society. (June 25 2015). ''Natural uranium'' [Online], Available: https://www.euronuclear.org/info/encyclopedia/n/naturaluranium.htm</ref> Most reactors require a higher percentage of uranium-235 in order to sustain nuclear fission reactions, which can be done through [[uranium enrichment]] processes.

===Moderator===
<html>
<iframe id='moderation' scrolling='no' src='http://energyeducation.ca/simulations/nuclear/fission.html' style='overflow:visible;max-width:525px;width:600px;height:525px;border:1 px solid black'></iframe>
</html>
:''[[neutron moderator|main article]]''

Moderators are used to slow down the neutrons produced from fission. This is necessary because many nuclear fuels (uranium-235, for instance) require neutrons to be slow-moving in order to absorb them. Nuclei with low mass numbers are most effective at doing so, therefore materials like [[water]] or [[graphite]] are often used.<ref name=ine>J.R. Lamarsh and A.J. Baratta, "Components of Nuclear Reactors" in ''Introduction to Nuclear Engineering'', 3rd ed., Upper Saddle River, NJ: Prentice Hall, 2001, ch.4, sec.4, pp. 133-136</ref>

Most reactors use [[light water]] as a moderator, such as [[pressurized water reactor]]s and [[boiling water reactor]]s. Carbon works similarly and is used in reactors such as the [[RBMK]]. A third type of moderator used in [[CANDU reactor]]s is [[heavy water]], which is water composed of heavy hydrogen rather than normal hydrogen.

The simulation to the right should help in visualizing how a moderator does its job: neutrons that are going too fast are absorbed by uranium-238 and do not yield fission (green) and the moderated neutrons are absorbed by uranium-235 which splits into smaller atoms and produces excess neutrons to continue the reaction (red).

===Coolant===

The coolant, as its name implies, is used to remove heat from the core and move it to somewhere that it is useful.<ref name=ine/> This keeps the fuel from overheating and melting down, at the same time as transferring the heat to water to make steam. Light water, heavy water, and various gases are the most common coolants for nuclear reactors. Coolants may also serve as the moderator, as is the case in many water-moderated reactors.

===Control rods===
:''[[control rod|main article]]''

Control rods can be inserted into the reactor core to reduce the amount of fuel which undergoes fission reactions. The rods contain neutron absorbing atoms such as gadolinium or cadmium. By absorbing neutrons within the core, it prevents those neutrons from reacting with the fuel. Control rod movement can be used to adjust the number of reactions occurring at the core, or fully inserted to shut down the reactor completely.

===Safety systems===

Safety systems are those in place to shut down the reactor and prevent radioactive material from being released. Some systems are passive, such as the dropping the control rods into the reactor core in CANDU reactors. The control rods are suspended above the core and held there by an [[electromagnet]] (a [[magnet]] which requires a constant supply of [[electricity]] to operate). In the event that a loss of power occurs, the control rods work to stop the reactions in the core. Strong [[reactor building|containment building]]s must also surround the reactor to prevent any radioactive leaks or external damage to the reactor.<ref name=ine2>J.R. Lamarsh and A.J. Baratta, "Principles of Nuclear Power Plant Safety" in ''Introduction to Nuclear Engineering'', 3rd ed., Upper Saddle River, NJ: Prentice Hall, 2001, ch.11, sec.3, pp. 623-630</ref>

Other safety systems require activation. An example of such a system is the release of large quantities of water to surround the reactor core. This provides cooling for the core to disperse the thermal energy and avoid a melt down.

===Economics===
The building of nuclear reactors is economically intensive. The initial capital costs are high compared to fossil fuel plants with similar output. Nuclear power requires a high amount of additional safety, and is completely responsible for all possible waste. What makes nuclear power economically feasible is the large amount of energy that comes from a small volume of fuel. This relationship is known as [[energy density]], and provides a cost advantage to using nuclear fuels. The cost of fuel is relatively lower for a nuclear power plant compared to fossil fuels. This is what makes nuclear reactors competitive despite high initial capital costs.

===Reactor types===
Nuclear power consists of various types of nuclear reactors. These include:
* [[CANDU reactor]]s
* [[Fast breeder reactor]]s
* [[Thorium reactor]]s
* [[Boiling water reactor]]s
* [[Pressurized water reactor]]s / [[Prismatic reactors]]
* [[Molten salt reactor]]s
* [[Small modular reactor]]s
* [[Radioisotope thermal generator]]s
* [[Fusion reactor]]s
* [[RBMK]]s
* [[Magnox reactor]]s
* [[Pebble bed reactor]]s
* [[Supercritical water cooled reactor]]s
* [[AES-2006/VVER-1000]]
* [[VHTR]]
* [[HTGR]]
* [[Research reactor]]s

==References==
{{reflist}}
[[Category:Uploaded]]