Editing Nuclear reactor (section)

===Future and developing technologies===

====Advanced reactors====
More than a dozen advanced reactor designs are in various stages of development.<ref name="UIC">{{cite web |title=Advanced Nuclear Power Reactors |publisher=[[World Nuclear Association]] |url=http://world-nuclear.org/info/inf08.html |access-date=29 January 2010 |archive-date=6 February 2010 |archive-url=https://web.archive.org/web/20100206181830/http://www.world-nuclear.org/info/inf08.html |url-status=dead }}</ref> Some are evolutionary from the [[pressurized water reactor|PWR]], [[boiling water reactor|BWR]] and [[Pressurised Heavy Water Reactor|PHWR]] designs above, and some are more radical departures. The former include the [[advanced boiling water reactor]] (ABWR), two of which are now operating with others under construction, and the planned [[passively safe]] [[Economic Simplified Boiling Water Reactor]] (ESBWR) and [[AP1000]] units (see [[Nuclear Power 2010 Program]]).
* The [[integral fast reactor]] (IFR) was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces only a fraction of the waste of current reactors.<ref name="pbs">{{cite web |url=https://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html |title=Nuclear Reaction: Why Do Americans Fear Nuclear Power? |access-date=9 November 2006 |publisher=Public Broadcasting Service (PBS) |author=Till, Charles |archive-date=17 April 2018 |archive-url=https://web.archive.org/web/20180417094454/https://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html |url-status=live }}</ref>
* The [[pebble-bed reactor]], a [[high-temperature gas-cooled reactor]] (HTGCR), is designed so high temperatures reduce power output by [[Doppler broadening]] of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium. Helium is not subject to steam explosions, resists neutron absorption leading to radioactivity, and does not dissolve contaminants that can become radioactive. Typical designs have more layers (up to 7) of passive containment than light water reactors (usually&nbsp;3). A unique feature that may aid safety is that the fuel balls actually form the core's mechanism, and are replaced one by one as they age. The design of the fuel makes fuel reprocessing expensive.
* The [[small, sealed, transportable, autonomous reactor]] (SSTAR) is being primarily researched and developed in the US, intended as a fast breeder reactor that is passively safe and could be remotely shut down in case the suspicion arises that it is being tampered with.
* The [[Clean and Environmentally Safe Advanced Reactor]] (CAESAR) is a nuclear reactor concept that uses steam as a moderator – this design is in development.
* The [[reduced moderation water reactor]] builds upon the [[Advanced boiling water reactor]] ABWR) that is presently in use. It is not a complete fast reactor instead using mostly [[epithermal neutron]]s, which are between thermal and fast neutrons in speed.
* The [[hydrogen-moderated self-regulating nuclear power module]] (HPM) is a reactor design emanating from the [[Los Alamos National Laboratory]] that uses [[uranium hydride]] as fuel.
* [[Subcritical reactor]]s are designed to be safer and more stable, but pose a number of engineering and economic difficulties. One example is the [[energy amplifier]].
* Thorium-based reactors – It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, thorium, which is four times more abundant than uranium, can be used to breed U-233 nuclear fuel.<ref name=NASA>{{cite journal|last1=Juhasz|first1=Albert J.|last2=Rarick|first2=Richard A.|last3=Rangarajan|first3=Rajmohan|title=High Efficiency Nuclear Power Plants Using Liquid Fluoride Thorium Reactor Technology|url=https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090038711.pdf|website=NASA|date=October 2009|access-date=27 October 2014|archive-date=28 April 2021|archive-url=https://web.archive.org/web/20210428205700/https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090038711.pdf|url-status=live}}</ref> U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.
** [[Advanced heavy-water reactor]] (AHWR) – A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the [[Bhabha Atomic Research Centre]] (BARC), India.
** [[KAMINI]] – A unique reactor using Uranium-233 isotope for fuel. Built in India by [[Bhabha Atomic Research Centre|BARC]] and Indira Gandhi Center for Atomic Research ([[IGCAR]]).
** India is also planning to build fast breeder reactors using the thorium – Uranium-233 fuel cycle. The FBTR (Fast Breeder Test Reactor) in operation at [[Kalpakkam]] (India) uses Plutonium as a fuel and liquid sodium as a coolant.
** China, which has control of the [[Cerro Impacto]] deposit, has a reactor and hopes to replace [[coal energy]] with nuclear energy.<ref name=sch>{{cite web|url=https://supchina.com/2019/01/14/venezuela-china-explained-2/|title=The Venezuela-China relationship, explained: Belt and Road {{!}} Part 2 of 4|date=14 January 2019|website=SupChina|language=en-US|access-date=24 June 2019|archive-url=https://web.archive.org/web/20190624005848/https://supchina.com/2019/01/14/venezuela-china-explained-2/|archive-date=24 June 2019|url-status=dead}}</ref>

Rolls-Royce aims to sell nuclear reactors for the production of [[synfuel]] for aircraft.<ref>{{cite web |url=https://www.bloomberg.com/amp/news/articles/2019-12-06/rolls-royce-pitches-nuclear-reactors-as-key-to-clean-jet-fuel |title=Rolls-Royce Touts Nuclear Reactors as Key to Clean Jet Fuel |website=[[Bloomberg News]] |access-date=19 December 2019 |archive-date=19 December 2019 |archive-url=https://web.archive.org/web/20191219210954/https://www.bloomberg.com/amp/news/articles/2019-12-06/rolls-royce-pitches-nuclear-reactors-as-key-to-clean-jet-fuel |url-status=dead }}</ref>

====Generation IV reactors====
[[Generation IV reactor]]s are a set of theoretical nuclear reactor designs. These are generally not expected to be available for commercial use before 2040–2050,<ref name="sa-2014">{{Cite web |last=De Clercq |first=Geert |date=October 13, 2014 |title=Can Sodium Save Nuclear Power? |url=https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ |access-date=2022-08-10 |website=Scientific American |language=en |archive-date=29 July 2021 |archive-url=https://web.archive.org/web/20210729090905/https://www.scientificamerican.com/article/can-sodium-save-nuclear-power/ |url-status=live }}</ref> although the World Nuclear Association suggested that some might enter commercial operation before 2030.<ref name="gen-iv_wna-2020">[https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/generation-iv-nuclear-reactors.aspx ''Generation IV Nuclear Reactors''] {{Webarchive|url=https://web.archive.org/web/20230330074852/https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/generation-iv-nuclear-reactors.aspx |date=30 March 2023 }}. World Nuclear Association, update Dec 2020</ref> Current reactors in operation around the world are generally considered second- or third-generation systems, with the first-generation systems having been retired some time ago. Research into these reactor types was officially started by the Generation&nbsp;IV International Forum (GIF) based on eight technology goals. The primary goals being to improve nuclear safety, improve proliferation resistance, minimize waste and natural resource utilization, and to decrease the cost to build and run such plants.<ref name="UIC1">{{cite web |title=Generation IV Nuclear Reactors |publisher=[[World Nuclear Association]] |url=http://world-nuclear.org/info/inf77.html |access-date=29 January 2010 |archive-date=23 January 2010 |archive-url=https://web.archive.org/web/20100123063413/http://www.world-nuclear.org/info/inf77.html |url-status=dead }}</ref>
* [[Gas-cooled fast reactor]]
* [[Lead-cooled fast reactor]]
* [[Molten-salt reactor]]
* [[Sodium-cooled fast reactor]]
* [[Supercritical water reactor]]
* [[Very-high-temperature reactor]]

====Generation V+ reactors====
Generation V reactors are designs which are theoretically possible, but which are not being actively considered or researched at present. Though some generation V reactors could potentially be built with current or near term technology, they trigger little interest for reasons of economics, practicality, or safety.
* Liquid-core reactor. A closed loop [[Nuclear thermal rocket#Liquid core|liquid-core nuclear reactor]], where the fissile material is molten uranium or uranium solution cooled by a working gas pumped in through holes in the base of the containment vessel.
* [[Gaseous fission reactor|Gas-core reactor]]. A closed loop version of the [[Nuclear lightbulb|nuclear lightbulb rocket]], where the fissile material is gaseous uranium hexafluoride contained in a fused silica vessel. A working gas (such as hydrogen) would flow around this vessel and absorb the UV light produced by the reaction. This reactor design could also function [[Gas core reactor rocket|as a rocket engine]], as featured in Harry Harrison's 1976 science-fiction novel ''Skyfall''. In theory, using UF<sub>6</sub> as a working fuel directly (rather than as a stage to one, as is done now) would mean lower processing costs, and very small reactors. In practice, running a reactor at such high power densities would probably produce unmanageable [[neutron flux]], weakening most [[IFMIF|reactor materials]], and therefore as the flux would be similar to that expected in fusion reactors, it would require similar materials to those selected by the [[IFMIF|International Fusion Materials Irradiation Facility]].
** Gas core EM reactor. As in the gas core reactor, but with [[photovoltaic]] arrays converting the [[UV light]] directly to electricity.<ref>{{cite web |url=http://isjaee.hydrogen.ru/pdf/AEE04-07_Prelas.pdf |title=International Scientific Journal for Alternative Energy and Ecology, DIRECT CONVERSION OF NUCLEAR ENERGY TO ELECTRICITY, Mark A. Prelas |url-status=dead |archive-url=https://web.archive.org/web/20160304024833/http://isjaee.hydrogen.ru/pdf/AEE04-07_Prelas.pdf |archive-date=4 March 2016 |access-date=7 December 2013 }}</ref> This approach is similar to the experimentally proved [[photoelectric effect]] that would convert the X-rays generated from [[aneutronic fusion]] into electricity, by passing the high energy photons through an array of conducting foils to transfer some of their energy to electrons, the energy of the photon is captured electrostatically, similar to a [[capacitor]]. Since X-rays can go through far greater material thickness than electrons, many hundreds or thousands of layers are needed to absorb the X-rays.<ref>Quimby, D.C., High Thermal Efficiency X-ray energy conversion scheme for advanced fusion reactors, ASTM Special technical Publication, v.2, 1977, pp. 1161–1165</ref>
* [[Fission fragment reactor]]. A fission fragment reactor is a nuclear reactor that generates electricity by decelerating an ion beam of fission byproducts instead of using nuclear reactions to generate heat. By doing so, it bypasses the [[Carnot cycle]] and can achieve efficiencies of up to 90% instead of 40–45% attainable by efficient turbine-driven thermal reactors. The fission fragment ion beam would be passed through a [[magnetohydrodynamic generator]] to produce electricity.
* [[Hybrid nuclear fusion]]. Would use the neutrons emitted by fusion to fission a [[breeder reactor|blanket]] of [[fertile material]], like [[Uranium-238|U-238]] or [[thorium|Th-232]] and [[Nuclear transmutation|transmute]] other reactor's [[spent nuclear fuel]]/nuclear waste into relatively more benign isotopes.

====Fusion reactors====
{{Main|Fusion power}}
Controlled [[nuclear fusion]] could in principle be used in [[fusion power]] plants to produce power without the complexities of handling [[actinides]], but significant scientific and technical obstacles remain. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050. The [[ITER]] project is currently leading the effort to harness fusion power.