Small modular reactor

{{Short description|Type of nuclear fission reactor}} {{Use dmy dates|date=November 2025}} [[File:Figure 4 Illustration of a light water small modular nuclear reactor (SMR) (20848048201).jpg|thumb|Illustration of a light water small modular nuclear reactor (SMR)]]

A '''small modular reactor''' ('''SMR''') is an emergent class of nuclear fission reactors with a rated electrical power of less than 300 megawatts (MWe), which use modular design principles to achieve streamlined construction and enhanced scalability compared to large light-water reactors.<ref name="Hussein2020"/><ref name=steigerwald-20231015/> Many SMR designs are intended to be built in factories and transported to installation sites as prefabricated modules, while others are designed for flexible multi-unit configurations.<ref name="Hussein2020">{{cite journal |last1=Hussein |first1=Esam M. A. |title=Emerging small modular nuclear power reactors: A critical review |journal=Physics Open |date=2020 |volume=5 |article-number=100038 |doi=10.1016/j.physo.2020.100038 |doi-access=free |bibcode=2020PhyO....500038H }}</ref>

The term SMR refers to the physical size, electrical capacity, and modular construction approach.<ref name="NuclearNewsSMRHistory"/> Reactor technology varies significantly among SMR designs. As of March 2026, most SMR designs are light-water reactors (LWRs),<ref name="WNASMRs" /> however SMR concepts encompass various reactor types, including Generation IV, thermal-neutron reactors, fast-neutron reactors, molten salt reactor, and gas-cooled reactor models.<ref name="WNASMRs" /><ref name="SustainabilityTimes_2019-11-29" /> Many SMRs also incorporate passive safety features.<ref name="Hussein2020"/>

Commercial SMRs are designed to deliver an electrical power output as low as 10 MWe and up to 300 MWe per module.{{efn|No definitive range for SMR power levels exists, but 10 MW to 300 MW is generally accepted.<ref name=":24"/>}} Reactors below 10 MWe in capacity are considered nuclear microreactors.<ref>{{cite web |last1=Reitsma |first1=F. |last2=Subki |first2=M. H. |last3=Luque-Gutierrez |first3=J. C. |last4=Bouchet |first4=S. |date=2020 |title=Advances in Small Modular Reactor Technology Developments |edition=2020 |url=https://aris.iaea.org/Publications/SMR_Book_2020.pdf |access-date=2026-04-19}}</ref> SMRs may also be designed purely for desalination or process heat rather than electricity. These SMRs are measured in megawatts thermal (MWt). Many SMR designs plan for customers to simply add modules to achieve a desired electrical output rather than scaling the size of the reactor.<ref name="SMRs3">{{cite book |last=Ingersoll |first=Daniel T. |date=2016 |chapter=Chapter 3: The rise of current small modular reactors (2000–2015) |title=Small Modular Reactors: Nuclear Power Fad Or Future? |doi=10.1016/B978-0-08-100252-0.00003-3 |isbn=978-0-08-100252-0}}</ref>{{rp|53}} These reactors are also expected to enhance safety through passive safety systems that operate without external power or human intervention during emergency scenarios, although this is not specific to SMRs but rather a characteristic of most modern reactor designs. SMRs are also claimed to have lower power plant staffing costs, as their operation is fairly simple,<ref name="auto22" /><ref name=":0b" /> and are claimed to have the ability to bypass financial and safety barriers that inhibit the construction of conventional reactors.<ref name=":0b" /><ref name=":1" />

SMRs have attracted strong interest from technology companies, such as Google and Microsoft, for use in powering data centers to meet demand driven by the AI boom.<ref name="NYTDataCenters">{{cite news |last1=Penn |first1=Ivan |last2=Weise |first2=Karen |date=2024-10-16 |title=Hungry for Energy, Amazon, Google and Microsoft Turn to Nuclear Power |newspaper=The New York Times |url=https://www.nytimes.com/2024/10/16/business/energy-environment/amazon-google-microsoft-nuclear-energy.html |access-date=2026-04-19}}</ref> Modular reactors are expected to reduce construction costs and time compared to large light-water reactors, as well as allow data center operators to draw power exclusively from a behind-the-meter SMR without purchasing electricity from the power grid.<ref name="POWERDataCenters">{{cite magazine |last=Patel |first=Sonal C. |date=2025-03-03 |title=The SMR Gamble: Betting on Nuclear to Fuel the Data Center Boom |magazine=POWER |url=https://www.powermag.com/the-smr-gamble-betting-on-nuclear-to-fuel-the-data-center-boom/ |access-date=2026-04-19}}</ref>

== Definition == According to the American Nuclear Society (ANS), while small or modular reactor concepts date back to the 1950s, the term "small modular reactor" first entered common use in the late 1970s.<ref name="ANSTBT">{{cite web |author=American Nuclear Society |date=2026-02-13 |title=Throwback Thursday: SMRs |url=https://american-nuclear-society.read.axioshq.com/p/unclear-newswire-daily-practice/cd1cce08-41ff-459e-b0b3-a91c620f6618/2c3d4d09-6222-495b-b9cf-3fa84543952a |publisher=Axios |access-date=2026-03-28}}</ref> Since then, the definition of an SMR has remained somewhat controversial.<ref name="Trikouros2012">{{cite journal |last=Trikouros |first=Nicholas |date=2012 |title=A Perspective on Small Reactor Licensing and Implementation |journal=Nuclear Technology |volume=178 |issue=2 |pages=233–239 |url=https://www.tandfonline.com/doi/abs/10.13182/NT12-A13562 |url-access=subscription |doi=10.13182/NT12-A13562 |bibcode=2012NucTe.178..233T |quote=Although discussions of small reactors commonly entail the use of the acronym 'SMR,' the exact meaning of the acronym appears to be somewhat controversial.}}</ref>

John Fabian, writing in ''Nuclear Newswire'', stated in 2026 that until around 2011, the abbreviation "SMR" referred either to "small modular reactor" or "small and medium sized reactor". According to Fabian, "the way 'SMR' is being used today does not seem consistent and is design dependent."<ref name="NuclearNewsSMRHistory">{{cite news |last=Fabian |first=John |date=2024-01-12 |title=Scratching the surface of SMR history: What's in a name? |newspaper=Nuclear Newswire |publisher=American Nuclear Society |url=https://www.ans.org/news/article-5635/scratching-the-surface-of-smr-history-whats-in-a-name/ |access-date=2026-03-27}}</ref> For example, as of 2026 the United States Nuclear Regulatory Commission (NRC) defines SMRs as only light-water reactors under 300 MWe, while non-LWR designs are considered "advanced reactors".<ref name="NuclearNewsSMRHistory"/><ref name="NRCAdvancedReactors">{{cite web |author= |date=2026-02-10 |title=Advanced Reactors {{!}} Nuclear Regulatory Commission |website=United States Nuclear Regulatory Commission |url=https://www.nrc.gov/reactors/new-reactors/advanced |access-date=2026-03-27}}</ref> At the same time, the World Nuclear Association defines SMRs as any reactor under 300 MWe so long as it is designed with modular technology.<ref name="WNASMRs"/> According to Fabian, the classification of reactors as SMRs based on their power output has remained consistent, with reactors under 300 MWe being classified as SMRs.<ref name="NuclearNewsSMRHistory"/>

As of 2023, there was broad consensus in the nuclear industry that SMRs are defined as nuclear reactors designed intentionally for low power (below 300 MWe) and with modular design applied either to individual components or the entire assembly.<ref name=steigerwald-20231015/>

== Operational SMRs == {{As of|2026}}, only China and Russia have successfully built operational SMRs.<ref name="CNBC">{{Cite web |last1=Kimball |first1=Spencer |last2=Cortés |first2=Gabriel |date=7 September 2024 |title=Small nuclear reactors could power the future — the challenge is building the first one in the U.S. |url=https://www.cnbc.com/2024/09/07/how-small-modular-reactors-could-expand-nuclear-power-in-the-us.html |website=CNBC |access-date=7 September 2024}}</ref><ref>{{Cite web |title=Small Modular Reactor (SMR) Global Project Tracker - World Nuclear Association |url=https://world-nuclear.org/information-library/nuclear-power-reactors/small-modular-reactors/small-modular-reactor-smr-global-tracker |access-date=2026-05-11 |website=world-nuclear.org}}</ref> Russia has been operating a floating nuclear power plant Akademik Lomonosov, in Russia's Far East (Pevek), commercially since 2020.<ref name="klt-40_pris" /> China's pebble-bed modular high-temperature gas-cooled reactor HTR-PM was connected to the grid in 2021.<ref name="nei-20230118" />

As of 2025, there were 127 modular reactor designs, with seven designs operating or under construction, 51 in the pre-licensing or licensing process, and 85 designers in discussions with potential site owners.<ref name=wnn-20250723>{{cite news |url=https://www.world-nuclear-news.org/articles/there-are-now-127-different-smr-designs-finds-nea-report |title=There are now 127 different SMR designs, finds NEA report |website=World Nuclear News |date=23 July 2025 |access-date=10 August 2025}}</ref>

== Background == While small modular reactors have experienced a resurgence in the 2000s, they are not a novel concept, and have been under development for many decades.<ref name="NuclearPowerReactorDesigns" />

=== Early small reactors === Small reactors have been used for military use since the 1950s for nuclear marine propulsion.<ref name="WNA-NMP">{{Cite web |date=4 February 2025 |title=Nuclear-Powered Ships: Nuclear Propulsion Systems |url=http://www.world-nuclear.org/information-library/non-power-nuclear-applications/transport/nuclear-powered-ships.aspx |publisher=World Nuclear Association}}</ref> The thermal output of the largest naval reactor as of 2025 is estimated at 700 MWt (the A1B reactor), similar in capacity to some large SMR plant designs. Naval nuclear reactors have had an excellent record of safety. According to public information, the US Navy's Naval Reactors program has never succumbed to a meltdown or radioactive release over its 60 years of service. In 2003, Admiral Frank Bowman backed up the Navy's claim by testifying no such accident has ever occurred.<ref>{{cite web |title=NASA's organizational and management challenges in the wake of the Columbia disaster |url=https://www.congress.gov/event/108th-congress/house-event/LC15416/text |website=www.congress.gov |quote="our nuclear‑powered ships ... have steamed ... without a reactor accident ... with no measurable negative impact on the environment or human health" |date=29 October 2003}}</ref> Several nuclear-powered commercial vessels have also been constructed, including four nuclear freighters and nine nuclear icebreakers.<ref name=":24"/>

Lawrence R. Hafstad, the Director of Reactor Development at the United States Atomic Energy Commission, proposed building small, cheap, transportable nuclear power packages for use in remote areas.<ref name="Weinberg1952">{{cite magazine |last=Weinberg |first=Alvin M. |date=November 1952 |title=Wanted: Smaller and More Reactors |url=https://archive.org/details/sim_nucleonics_1952-11_10_11/page/32/mode/2up |magazine=Nucleonics |volume=10 |issue=11 |page=32 |department=Editorial |publisher=The McGraw-Hill Companies |access-date=}}</ref><ref name="Murray1954"> {{cite book |last=Murray |first=Raymond L. |date=1954 |title=Introduction to Nuclear Engineering |publisher=Prentice-Hall |publication-place=Englewood Cliffs, NJ |page=376 |quote=A new point of view that at this writing appears to be gaining considerable favor is that the demand for the multi-million dollar reactors that can produce power at a price of around 5 mills/kWhr is small, and that small "power package" reactors should be developed.}}</ref> Alvin M. Weinberg, Director of Research at Oak Ridge National Laboratory (ORNL), wrote in support of Hafstad's proposal in 1952, adding that the naval reactors could provide a basis for developing nuclear power packages. He suggested that building many small reactors for remote sites would reduce the financial risk of establishing a nuclear industry:<ref name="Weinberg1952"/>

{{blockquote| The main advantage of the power-package approach to establishment of a nuclear energy industry is that the technology would rely on comparatively many small units, rather than on a very few enormous ones. Thus industry would not try to hit the jackpot right off, but would edge into the business a little at a time and at each stage would be able to match its risk with its financial capability. |author=Alvin Weinberg |title="Wanted: Smaller and More Reactors" |source=''Nucleonics'' (November 1952) }}

Between 1954 and 1977, the US Army experimented with powering military installations with small land-based reactors during the Army Nuclear Power Program.<ref name="WNASMRs" /> The preliminary design for one such reactor was produced by ORNL under Weinberg's supervision.<ref>{{cite news |last=Swift |first=Thomas P. |date=1954-03-21 |title=Wanted: A Contractor to Build A Portable Atomic Power Plant |newspaper=The New York Times |url=https://www.nytimes.com/1954/03/21/archives/wanted-a-contractor-to-build-a-portable-atomic-power-plant-a-e-c.html |access-date=2026-04-16}}</ref> One of the Army reactors, PM-2A, was noted as extensively utilizing prefabricated modules to achieve lower construction cost.<ref>{{cite report |last=Barnett |first=James W. |date=1961-08-01 |title=Construction of the Army nuclear power plant PM-2A at Camp Century, Greenland: Final report |url=https://usace.contentdm.oclc.org/digital/collection/p266001coll1/id/3968/rec/3 |publisher=Dept. of the Army, Office of the Chief of Engineers, Nuclear Power Division}}</ref>

Military small reactors are quite different from commercial SMRs. Historically, the military relied on highly enriched uranium (HEU) to power their reactors and not the low-enriched uranium (LEU) fuel used by SMRs. This is because submarine reactors are severely space-constrained and require higher power density than civilian reactors.<ref name="WNA-NMP" /> Many naval reactors also operate for over a decade or more without refueling.<ref name="WNA-NMP" />

Early land-based reactors constructed in the United States were relatively small, such as the 60 MW Shippingport Atomic Power Station and the 250 MW Indian Point Unit 1. However, these reactors were intended to be scaled up into large central-station power plants, to take advantage of economies of scale. Soon after the first successful nuclear demonstrations, utilities raced to scale up plants before operational experience could be gained from smaller units.<ref name="SMRs2">{{cite book |last=Ingersoll |first=Daniel T. |date=2016 |chapter=Chapter 2: A brief history of small nuclear power (1950–2000) |title=Small Modular Reactors: Nuclear Power Fad Or Future? |doi=10.1016/B978-0-08-100252-0.00003-3 |isbn=978-0-08-100252-0}}</ref>{{rp|28{{ndash}}29}} While traditional engineering wisdom dictates that a system should be scaled up twofold, by the time many nuclear plants with capacities exceeding 1000 MW were being ordered and constructed, no reactor larger than 250 MW was operational.{{efn|"The 10-year lag time in the design, engineering, licensing, and construction of new plants created a situation in which utilities were ordering (and vendors were selling) plants that were sixfold larger than current operational experience. This compares to a more traditional rule of thumb that recommends a twofold scale-up for complex engineered systems. The more aggressive approach employed by the nuclear industry required a significant leap of faith, which unfortunately did not play out well."<ref name="SMRs2"/>}} While nuclear power plants were formerly designed as effectively standardized designs, the growth of operational issues and new safety requirements led to plants being designed and built as "one-of-a-kind" designs, further increasing cost, construction, and licensing issues.<ref name="SMRs2"/> Reactor orders soon fell off sharply, and none of the plants ordered after 1974, except Watts Bar Unit 2, were ever constructed. The nuclear industry, throughout the following decades, would focus on optimizing the existing large reactors, whose average capacity factors rose from 50% to 90% by the mid-2000s.<ref name="SMRs3"/>

=== Renewed interest === In 1982, the Electric Power Research Institute (EPRI) conducted a study that recommended smaller, less capital-intensive, and inherently safe reactors be designed instead of large light-water reactors. Weinberg, then the director of the Institute for Energy Analysis, conducted a related study into inherently safe reactors. It concluded that such a system was possible, and selected the 400 MW Swedish Process Inherent Ultimate Safety (PIUS) and 100 MW American Modular High Temperature Gas-cooled Reactor (MHTGR) designs as the most intrinsically safe.<ref name="SMRs2"/> At this time, multiple high-temperature gas-cooled reactors were being designed with the intention of building a large plant out of several modular low-power reactors.<ref>{{cite book |last1=Kugeler |first1=Kurt |last2=Zhang |first2=Zuoyi |date=2019 |title=Modular High-temperature Gas-cooled Reactor Power Plant |url=https://link.springer.com/book/10.1007/978-3-662-57712-7 |publisher=Springer Berlin |publication-place=Heidelberg |page=637 |doi=10.1007/978-3-662-57712-7 |isbn=978-3-662-57712-7}}</ref> The PIUS reactor,<ref>{{cite book |last=Aydogan |first=Fatih |date=2023 |chapter=Small Modular Reactors (SMRs) |title=Handbook of Generation IV Nuclear Reactors |quote=The historical development of SMRs started with integrated reactor designs, such as SIR and PIUS. |publisher=Woodhead Publishing |edition=2nd |url=https://www.sciencedirect.com/science/chapter/edited-volume/pii/B9780128205884000268 |url-access=subscription |doi=10.1016/C2019-0-01219-8 |isbn=978-0-12-820588-4}}</ref> with its reactor vessel situated within a large pool of borated water, and the robust TRISO fuel of the General Atomics MHTGR influenced subsequent SMR design features. Several small prefabricated reactor designs were developed around the same time in the UK, France, and Germany, however none were constructed. The EPRI study also led to the Department of Energy's (DOE) Advanced Light Water Reactor program, which resulted in the development of two 600 MW LWRs, the General Electric ABWR and later SBWR, and the Westinghouse AP-600 designs. However, these were later scaled up significantly into the ESBWR and AP-1000 reactors.<ref name="SMRs2"/> Two AP-1000 reactors were later constructed as Vogtle Units 3 and 4, together costing $30 billion due to delays and cost overruns.

The DOE also ran an Advanced Liquid-Metal Reactor program, which led to the development of the Power Reactor Inherently Safe Module (PRISM) SMR by General Electric in the 1980s and 1990s.<ref>{{cite web |last1=Triplett |first1=Brian S. |last2=Loewen |first2=Eric P. |last3=Dooies |first3=Brett J. |date=2010 |title=PRISM: A Competitive Small Modular Sodium-Cooled Reactor |url=https://wecanfigurethisout.org/ENERGY/Web_notes/Nuclear/Small_Modular_Reactors_Supporting_Files/PRISM%20-%20A%20Competitive%20Small%20Modular%20Sodium-Cooled%20Reactor%20-%20GE%20Hitachi%202010%20.pdf |doi=10.13182/NT178-186 |access-date=2026-04-26}}</ref><ref>{{cite magazine |last=Hylko |first=James M. |date=2011-08-01 |title=PRISM: A Promising Near-Term Reactor Option |url=https://www.powermag.com/prism-a-promising-near-term-reactor-option/ |magazine=POWER |access-date=2026-04-24}}</ref> Each 1400 MW PRISM plant would be composed of nine 160 MW reactor modules, which would each be factory-fabricated and shipped by rail to the construction site.<ref>{{cite tech report |author=Office of Nuclear Reactor Regulation |date=1994 |title=Preapplication Safety Evaluation Report for the Power Reactor Innovative Small Module (PRISM) Liquid-Metal Reactor |website=Nuclear Regulatory Commission |page=xxiii |quote=PRISM is a small, modular, pool-type, liquid-metal (sodium)-cooled reactor producing 471 MWt power. Three reactor modules constitute a power block, and up to three power blocks can be combined for a 1,395-MWe station. The reactor modules would be a standard design that would be built in a factory and shipped by rail to a site. |id=NUREG-1368 |url=https://www.nrc.gov/docs/ML0634/ML063410561.pdf |access-date=2026-05-11}}</ref> PRISM's use of multiple factory-fabricated modules to comprise a large power plant and its extensive use of passive safety features were both carried into later SMR designs.<ref name="Ingersoll 2009 589–603" /><ref name="SMRs2"/> In 1983, the International Atomic Energy Agency started the Small and Medium Power Reactor Project Initiation Study to survey designs for small and medium sized reactors. The Nuclear Energy Agency launched a follow-on study in 1991 that evaluated 17 small or medium-sized reactor concepts, including several from the DOE's Advanced Light Water and Liquid-Metal programs.<ref name="SMRs2"/>

Government support for reactor design steadily declined, leading to the DOE being issued no budget for nuclear development at all in 1998. However, in 1999 the DOE began the Nuclear Energy Research Initiative (NERI), followed by the Generation IV International Forum in 2000, and later the Global Nuclear Energy Partnership (GNEP) in 2006. The NERI program resulted in the development of multiple SMR designs, including liquid metal-cooled reactors and SMRs designed for process heat, as well as others based on existing LWR technology.<ref name="SMRs3"/> In 2001, a report to Congress examining 50 MWe small modular reactors for powering remote areas, "found no substantive technical issues to hinder development and deployment of SMRs, and initial estimates of the electricity generation costs are comparable to, if not better than, those for current electricity supplies in typical remote areas."<ref name="Report to Congress">{{cite report |author=((Office of Nuclear Energy, Science, and Technology)) |date=May 2001 |title=Report to Congress on Small Modular Nuclear Reactors |publisher=United States Department of Energy |url=http://www.ne.doe.gov/pdfFiles/Cong-Rpt-may01.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110716055134/http://www.ne.doe.gov/pdfFiles/Cong-Rpt-may01.pdf |archive-date=2011-07-16 |access-date=2026-05-11}}</ref> One concept, the IRIS SMR, would later receive significant commercial interest and funding under the GNEP, while another, the MASLWR, later formed the basis for NuScale's SMR. The GNEP and its associated programs also catalyzed significantly greater industry and utility interest in developing SMRs.<ref name="SMRs3"/>

The term "small modular reactors" as opposed to "small-and-medium-sized reactors" was brought to wider use when US Secretary of Energy Steven Chu identified "small modular reactors" as "America's new nuclear option" in a 2010 ''Wall Street Journal'' op-ed, where he stated "SMRs would be ready to 'plug and play' upon arrival [on site]" and be more affordable.<ref name=steigerwald-20231015/> He announced that President Barack Obama had requested $39{{nbsp}}million for a new SMR design and licensing program.<ref name=wsj-20100323>{{cite news |url=https://www.energy.gov/articles/secretary-chu-op-ed-small-modular-reactors-wall-street-journal |title=America's New Nuclear Option - Small modular reactors will expand the ways we use atomic power |last=Chu |first=Steven |newspaper=Wall Street Journal |date=23 March 2010 |via=U.S. Department of Energy |archive-url=https://web.archive.org/web/20140705131311/https://www.energy.gov/articles/secretary-chu-op-ed-small-modular-reactors-wall-street-journal |archive-date=5 July 2014}}</ref>

However, the reactors that were ordered at the time as part of the expected nuclear renaissance were all large light-water plants. Almost all of these projects failed, largely due to slow federal funding, little growth in electricity consumption, and the 2008 financial crisis, the effects of which were exacerbated by the high cost and financial risk of the plants.<ref name="NuclearPowerReactorDesigns">{{cite book |last1=Schlegel |first1=Joshua P. |last2=Bhowmik |first2=P.K. |date=2023 |chapter=Chapter 14 {{ndash}} Small modular reactors |title=Nuclear Power Reactor Designs: From History to Advances |url=https://www.sciencedirect.com/science/chapter/edited-volume/pii/B978032399880200014X |url-access=subscription |doi=10.1016/C2021-0-00402-8}}</ref> The Fukushima accident in 2011, while resulting in a significant loss of interest in nuclear energy, drew increased attention to SMRs. In 2012, the DOE began its SMR program in earnest, by which point interest in SMRs was significant.<ref name="SMRs3"/>

=== Hope of enhanced safety and reduced costs === Economic factors of scale mean that nuclear reactors tend to be large, to such an extent that size itself becomes a limiting factor.{{citation needed|date=June 2025}} Furthermore, the 1986 Chernobyl disaster caused a major setback for the nuclear industry, with worldwide suspension of development, cuts in funding, and closure of reactor plants.{{cn|date=November 2025}}

Proponents claim that SMRs would be less expensive due to the application of standardized modules that could be industrially produced off-site in a dedicated factory.<ref name="small-beautiful">{{Cite web |url=https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf |title=Is Small Really Beautiful? The Future Role of Small Modular Nuclear Reactors (SMRs) in the Military |last=Trakimavičius |first=Lukas |website=NATO Energy Security Centre of Excellence |language=en |access-date=28 December 2020 |archive-date=31 July 2022 |archive-url=https://web.archive.org/web/20220731034722/https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf }}</ref> SMRs do, however, also have economic disadvantages.<ref name="base_report">{{cite web |title=Small Modular Reactors - Was ist von den neuen Reaktorkonzepten zu erwarten? |periodical= |publisher= |url=https://www.base.bund.de/DE/themen/kt/kta-deutschland/neue_reaktoren/neue-reaktoren_node.html |last=Bundesamt für die Sicherheit der nuklearen Entsorgung |date=10 March 2021 |language=de |pages= |quote=}}</ref> Several studies suggest that the overall costs of SMRs are comparable with those of conventional large reactors. Moreover, extremely limited information about SMR modules transportation has been published.<ref name="transportation2">{{Cite conference |last1=Mignacca |first1=Benito |last2=Hasan Alawneh |first2=Ahmad |last3=Locatelli |first3=Giorgio |date=27 June 2019 |title=Transportation of small modular reactor modules: What do the experts say? |url=https://www.researchgate.net/publication/330823799 |conference=27th International Conference on Nuclear Engineering}}</ref> Critics say that modular building will only be cost-effective for a high number of the same SMR type, given the still remaining high costs for each SMR.<ref>{{Cite journal |last1=Boarin |first1=Sara |last2=Ricotti |first2=Marco E. |date=5 August 2014 |title=An Evaluation of SMR Economic Attractiveness |journal=Science and Technology of Nuclear Installations |language=en |volume=2014 |article-number=e803698 |doi=10.1155/2014/803698 |issn=1687-6075 |doi-access=free |hdl=11311/839526 |hdl-access=free}}</ref> A high market share is thus needed to obtain sufficient orders.

=== Contribution to the net zero emissions pathways === In February 2024, the European Commission recognized SMR technology as an important contributor to decarbonization as part of the EU Green Deal.<ref>{{Cite web |title=Small Modular Reactors explained - European Commission |url=https://energy.ec.europa.eu/topics/nuclear-energy/small-modular-reactors/small-modular-reactors-explained_en |access-date=11 February 2024 |website=energy.ec.europa.eu |language=en}}</ref>

In its pathway to reach global net zero emissions by 2050, the International Energy Agency (IEA) considers that worldwide nuclear power should be doubled between 2020 and 2050.<ref name="IEA2022">{{cite web |title=Nuclear power can play a major role in enabling secure transitions to low emissions energy systems |website=IEA |date=30 June 2022 |url=https://www.iea.org/news/nuclear-power-can-play-a-major-role-in-enabling-secure-transitions-to-low-emissions-energy-systems |access-date=13 December 2023}}</ref> Antonio Vaya Soler, an expert from the Nuclear Energy Agency (NEA), agrees that although renewable energy is essential to fight global warming, it will not be sufficient to achieve net zero {{CO2|link=carbon dioxide}} emissions and nuclear energy capacity should be at least doubled.<ref name="VayaSoler2024">{{cite book |first1=Antonio |last1=Vaya Soler |year=2024 |title=Chapter 23 – The future of nuclear energy and small modular reactors. In: Living with Climate Change |pages=465–512 |publisher=Elsevier |doi=10.1016/B978-0-443-18515-1.00012-5 |url=https://www.sciencedirect.com/science/article/abs/pii/B9780443185151000125 |isbn=978-0-443-18515-1 |access-date=13 December 2023}}</ref>

To produce the same electrical power as the {{nowrap|~ 400 large}} nuclear power reactors in the world today, BASE, the German Federal Office for the Safety of Nuclear Waste Management, warns that it would be necessary to build several thousand to tens of thousands of SMRs.<ref name="BASE">{{cite web |author=BASE, the German Federal Office for the Safety of Nuclear Waste Management |date=15 January 2023 |title=Small Modular Reactors (SMR) |url=https://www.base.bund.de/en/nuclear-safety/nuclear-technology/small-modular-reactors/small-modular-reactors.html |access-date=12 December 2023 |website=BASE}}</ref><ref name="BASE_report2021">{{cite web |date=10 March 2021 |author=Öko-Institut |title=Sicherheitstechnische Analyse und Risikobewertung einer Anwendung von SMR-Konzepten (Small Modular Reactors) |trans-title=Safety analysis and risk assessment of the application of SMR concepts |website=BASE |url=https://www.base.bund.de/SharedDocs/Downloads/BASE/DE/berichte/kt/gutachten-small-modular-reactors.html;jsessionid=268D8A1B8EE5F6F621FDBCF3A5817292.internet992 |language=de |access-date=13 December 2023}}</ref>

Several fleets of SMRs of exactly the same type, industrially manufactured in large numbers, should be rapidly deployed worldwide to significantly reduce emissions of {{CO2}}. The Nuclear Energy Agency (NEA) launched at COP 28 an initiative ''Accelerating SMRs for Net Zero'' to foster collaboration between research organizations, nuclear industry, safety authorities, and governments, in order to reduce carbon emissions to net zero before 2050 to limit global surface temperature increase.<ref name="NEA2023a">{{cite web |title="Accelerating SMRs for Net Zero" initiative launched at COP28 |website=Nuclear Energy Agency (NEA) |date=5 December 2023 |url=https://www.oecd-nea.org/jcms/pl_88887/-accelerating-smrs-for-net-zero-initiative-launched-at-cop28 |access-date=13 December 2023}}</ref><ref name="NEA2023b">{{cite web |title=Accelerating SMRs for Net Zero |website=Nuclear Energy Agency (NEA) |date=5 December 2023 |url=https://www.oecd-nea.org/jcms/pl_88539/accelerating-smrs-for-net-zero |access-date=13 December 2023}}</ref><ref name="NEA2023c">{{cite web |author=Nuclear Energy Agency (NEA) |date=November 2023 |title=Small Modular Reactors (SMRs) for Net Zero |url=https://www.oecd-nea.org/upload/docs/application/pdf/2023-12/smrs_for_net_zero.pdf |access-date=13 December 2023}}</ref>

=== Future challenges === Proponents say that nuclear energy with proven technology can be safer; the nuclear industry contends that smaller size will make SMRs even safer than larger conventional plants. This is because the main problem associated with nuclear meltdowns is the decay heat that is present after reactor shutdown, which would be much lower for SMRs because of their lower power output. Critics say that many more<ref name="BASE" /> small nuclear reactors pose a higher risk, requiring more transportation of nuclear fuel and also increasing the production of radioactive waste.<ref name="Krall2022" /> SMRs require new designs with new technology, the safety of which has yet to be proven.

SMRs remain facing a distinct engineering risk of corrosion affecting critical systems and materials. Particularly in SMR systems that use liquid metals or molten salts cooling techniques.<ref name="SMRCorrosion">{{Cite journal |last1=Chmielewska-Śmietanko |first1=Dagmara |last2=Sartowska |first2=Bożena |date=2025-12-05 |title=Emerging Issues of Corrosion in Nuclear Power Plants: The Case of Small Modular Reactors |journal=Energies |language=en |volume=18 |issue=24 |pages=6376 |doi=10.3390/en18246376 |doi-access=free|issn=1996-1073}}</ref> Lack of a licensing process and safety framework has left limited SMRs in preventing potential corrosion levels produced in alternative SMR designs.<ref name="SMRCorrosion" />

Until 2020, no truly modular SMRs had been commissioned for commercial use.<ref name="Mignacca2">{{Cite journal |last1=Mignacca |first1=Benito |last2=Locatelli |first2=Giorgio |date=1 November 2019 |title=Economics and finance of Small Modular Reactors: A systematic review and research agenda |journal=Renewable and Sustainable Energy Reviews |volume=118 |article-number=109519 |doi=10.1016/j.rser.2019.109519 |doi-access=free |bibcode=2020RSERv.11809519M |issn=1364-0321 |hdl=11311/1204915 |hdl-access=free}}</ref> In May 2020, the first prototype of a floating nuclear power plant with two 30 MWe reactors – the type ''KLT-40'' – started operation in Pevek, Russia.<ref name="klt-40_pris" /> This concept is based on the design of nuclear icebreakers.<ref name="klt40">{{cite web |url=http://www.world-nuclear-news.org/Articles/Russia-connects-floating-plant-to-grid |title=Russia connects floating plant to grid |date=19 December 2019 |website=World Nuclear News |quote=Alexey Likhachov, director general of state nuclear corporation Rosatom, said Akademik Lomonosov had thus becomes the world's first nuclear power plant based on SMR technology to generate electricity.}}</ref> The operation of the first commercial land-based, 125 MWe demonstration reactor ''ACP100'' (Linglong One) is due to start in China by the end of 2026.<ref name="containment-linglong1" />

The introduction of SMRs has sparked social and institutional concern. Nuclear projects are of policy agendas, meaning centralization of SMRs. The distribution of SMRs has culminated in criticism and discussion of risk towards communities affected by lack of flexible energy.<ref name=":3">{{Cite journal |last=McCaluey |first=Darren |date=Dec 2025 |title=An energy justice critique of small modular reactors in emerging nuclear transitions |url=https://linkinghub.elsevier.com/retrieve/pii/S2214629625005389 |journal=Energy Research & Social Science |volume=130 |article-number=104457 |doi=10.1016/j.erss.2025.104457 |bibcode=2025ERSS..13004457M }}</ref> As any other energy source, communities are left out and potential environmental issues are needed to be assessed given the rate of expansion of SMR.<ref name=":3" />

== Designs == [[Image:Fission chain reaction.svg|thumb|A nuclear fission chain is required to generate nuclear power.]] SMRs are envisioned in multiple designs. Some are simplified versions of current reactors, others involve entirely new technologies.<ref>INEA, NEA, IEA. [http://www.nea.fr/ndd/reports/2002/nea3969-innovative-reactor.pdf "Innovative Nuclear Reactor Development: Opportunities for International Co-operation"], [http://www.nea.fr ''OECD Nuclear Energy Agency'']</ref> All proposed SMRs use nuclear fission with designs including thermal-neutron reactors and fast-neutron reactors.

=== Thermal-neutron reactors === Thermal-neutron reactors rely on a moderator (water, graphite, beryllium...) to slow neutrons and generally use {{chem|link=Uranium|235|U}} as fissile material. Most conventional operating reactors are of this type.

=== Fast reactors === Fast reactors do not use moderators. Instead, they rely on highly enriched uranium (HEU) fuel to absorb fast neutrons. This usually means changing the fuel arrangement within the core, or using different fuels. E.g., {{chem|link=Plutonium|239|Pu}} is more likely to absorb a fast neutron than {{chem|235|U}}.

Fast reactors can also be breeder reactors. These reactors release enough neutrons to transmute non-fissionable elements into fissionable ones. A common use for a breeder reactor is to surround the core by a "blanket" of {{chem|238|U}}, the most easily available isotope. Once the {{chem|238|U}} undergoes a neutron absorption reaction, it becomes {{chem|239|Pu}}, which can be removed from the reactor during refueling, and subsequently reprocessed and used as fuel.<ref name="world-nuclear1">Carlson, J. [http://www.world-nuclear.org/info/inf98.html "Fast Neutron Reactors"] {{Webarchive|url=https://web.archive.org/web/20130224035726/http://www.world-nuclear.org/info/inf98.html |date=24 February 2013 }}, [http://world-nuclear.org ''World Nuclear Association'']</ref>

== Technologies == [[File:Pumpless light water reactor.jpg|thumb|Diagram of NRC approved SMR type: Pumpless light water reactor developed by NuScale Power as mini nuclear reactor.]]

=== Coolant === Conventional light-water reactors typically use water as a coolant and neutron moderator.<ref name="nrc-201411052">{{citation |last=Glaser |first=Alexander |title=Small Modular Reactors - Technology and Deployment Choices |date=5 November 2014 |url=https://www.nrc.gov/reading-rm/doc-collections/commission/slides/2014/20141105/glaser-11-05-14.pdf |publisher=NRC |format=presentation}}</ref> SMRs may use water, liquid metal, gas and molten salt as coolants.<ref name="world-nuclear22">Wilson, P.D. [http://www.world-nuclear.org/info/inf32.html "Nuclear Power Reactors"] {{Webarchive|url=https://web.archive.org/web/20130212224059/http://www.world-nuclear.org/info/inf32.html |date=12 February 2013 }}, [http://www.world-nuclear.org ''World Nuclear Association'']</ref> Coolant type is determined based on the reactor type, reactor design, and the chosen application. Large-rated reactors primarily use light water as coolant, allowing for this cooling method to be easily applied to SMRs. Helium is often elected as a gas coolant for SMRs because it yields a high plant thermal efficiency and supplies a sufficient amount of reactor heat. Sodium, lead, and lead-bismuth eutectic (LBE) are liquid metal coolants studied for 4th generation SMRs. There was a large focus on sodium during early work on large-rated reactors which has since carried over to SMRs to be a prominent choice as a liquid metal coolant.<ref name=":24">{{Cite book |editor=Daniel T. Ingersoll and Mario D. Carelli |title=Handbook of Small Modular Nuclear Reactors |date=2020 |publisher=Woodhead Publishing |isbn=978-0-12-823917-9 |edition=2nd |doi=10.1016/C2019-0-00070-2 |oclc=1222802880}}</ref> SMRs have lower cooling water requirements, which expands the number of sites where a SMR could be built, including remote areas typically incorporating mining and desalination.<ref>{{Cite web |title=Small nuclear power reactors - World Nuclear Association |url=https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspx |access-date=16 February 2022 |website=www.world-nuclear.org}}</ref>

=== Thermal/electrical generation === Some gas-cooled reactor designs could drive a gas turbine, rather than boiling water, such that thermal energy can be used directly. Heat could also be used in hydrogen production and other industrial operations,<ref name="world-nuclear22"/> such as desalination and the production of petroleum derivative (extracting oil from oil sands, making synthetic oil from coal, etc.).<ref>[http://www.world-nuclear.org/info/inf116_processheat.html "Nuclear Process Heat for Industry"] {{Webarchive|url=https://web.archive.org/web/20130216022200/http://www.world-nuclear.org/info/inf116_processheat.html |date=16 February 2013 }}, [http://www.world-nuclear.org ''World Nuclear Association'']</ref>

=== Load following === SMR designs are generally expected to provide base load electrical power; some proposed designs are aimed to adjust their power output based on electricity demand.<ref>{{Cite journal |last1=Locatelli |first1=Giorgio |last2=Boarin |first2=Sara |last3=Fiordaliso |first3=Andrea |last4=Ricotti |first4=Marco E. |date=1 April 2018 |title=Load following of Small Modular Reactors (SMR) by cogeneration of hydrogen: A techno-economic analysis |url=https://www.sciencedirect.com/science/article/abs/pii/S0360544218300471 |journal=Energy |volume=148 |pages=494–505 |doi=10.1016/j.energy.2018.01.041 |bibcode=2018Ene...148..494L |issn=0360-5442 |hdl=11311/1046552 |hdl-access=free}}</ref>

Another approach, especially for SMRs designed to provide high temperature heat, is to adopt cogeneration, maintaining consistent heat output, while diverting otherwise unneeded heat to an auxiliary use. District heating, desalination and hydrogen production have been proposed as cogeneration options.<ref name="Cogeneration2">{{Cite journal |last1=Locatelli |first1=Giorgio |last2=Fiordaliso |first2=Andrea |last3=Boarin |first3=Sara |last4=Ricotti |first4=Marco E. |date=1 May 2017 |title=Cogeneration: An option to facilitate load following in Small Modular Reactors |url=https://eprints.whiterose.ac.uk/id/eprint/110233/1/Load%20Following%20by%20Cogeneration%20V27%20to%20deposit.pdf |journal=Progress in Nuclear Energy |volume=97 |pages=153–161 |doi=10.1016/j.pnucene.2016.12.012 |bibcode=2017PNuE...97..153L |issn=0149-1970 |hdl=11311/1046551 |hdl-access=free}}</ref>

Overnight desalination requires sufficient freshwater storage capacity to deliver water at times other than when it is produced.<ref name="LoadFollowing2014">{{Cite journal |last1=Locatelli |first1=Giorgio |last2=Boarin |first2=Sara |last3=Pellegrino |first3=Francesco |last4=Ricotti |first4=Marco E. |date=1 February 2015 |title=Load following with Small Modular Reactors (SMR): A real options analysis |url=https://eprints.whiterose.ac.uk/id/eprint/91139/1/Accpeted%20version.pdf |journal=Energy |volume=80 |pages=41–54 |doi=10.1016/j.energy.2014.11.040 |bibcode=2015Ene....80...41L |issn=0360-5442 |hdl-access=free |hdl=11311/881391}}</ref> Reverse osmosis membrane and thermal evaporators are the two main techniques for seawater desalination. The membrane desalination process uses only electricity to power water pumps and is the most employed of the two methods. In the thermal process, the feed water stream is evaporated in different stages with continuous decreases in pressure between the stages. The thermal process directly uses thermal energy and avoids the conversion of thermal power into electricity. Thermal desalination is further divided into two main technologies: the multi-stage flash distillation (MSF) and the Multi-Effect Desalination (MED).<ref name="LoadFollowing2014" />

== Nuclear safety == A report by the German Federal Office for the Safety of Nuclear Waste Management (BASE) considering 136 different historical and current reactors and SMR concepts stated: "Overall, SMRs could potentially achieve safety advantages compared to power plants with a larger power output, as they have a lower radioactive inventory per reactor and aim for a higher safety level especially through simplifications and an increased use of passive systems. In contrast, however, various SMR concepts also favour reduced regulatory requirements, for example, with regard to the required degree of redundancy or diversity in safety systems. Some developers even demand that current requirements be waived, for example in the area of internal accident management or with reduced planning zones, or even a complete waiver of external emergency protection planning. Since the safety of a reactor plant depends on all of these factors, based on the current state of knowledge it is not possible to state, that a higher safety level is achieved by SMR concepts in principle."<ref name="base_sicherheit">[https://www.base.bund.de/SharedDocs/Downloads/BASE/DE/berichte/kt/gutachten-small-modular-reactors.html ''Sicherheitstechnische Analyse und Risikobewertung einer Anwendung von SMR-Konzepten (Small Modular Reactors)'']. BASE, März 2021</ref><ref name="fortschritt_sz-2021">[https://www.sueddeutsche.de/wissen/atomenergie-kernkraft-atommuell-gates-reaktoren-smr-oeko-institut-gutachten-atomkraftwerk-1.5229758 ''Für die Zukunft zu spät.''] Süddeutsche Zeitung, 9. März 2021</ref><ref name=base_report/>

Negative temperature coefficients in the moderators and the fuels keep the fission reactions under control, causing the reaction to slow as temperature increases.<ref>{{harvnb|DOE-HDBK-1019|1993|pp=23–29}}</ref> After the shutdown of a nuclear reactor, the reactor needs to be cooled continuously in order to dissipate decay heat. A loss of emergency cooling such as in the Fukushima nuclear accident and the Three Mile Island accident can result in a nuclear meltdown when the temperature in the reactor becomes too high. Since the initial decay heat is a fraction of the reactor operating power, the lower operating power of SMRs makes them much safer since less heat needs to be dissipated.<ref>{{Cite book |last=Laufs |title=Reaktortechnik für Hochleistungskernkraftwerke |publisher=Springer |language=DE |trans-title=Reactor Technology for High Power Nuclear Power Plants}}</ref>

Some SMR designs proposes cooling systems only based on thermoconvection – natural circulation – to eliminate cooling pumps that could break down. Convection can keep removing decay heat after reactor shutdown. However, some SMRs may need an active cooling system to back up the passive system, increasing cost.<ref name="UCS1" />

Some SMR designs feature an integral design of which the primary reactor core, steam generator and the pressurizer are integrated within the sealed reactor vessel. This integrated design allows for the reduction of a possible accident as contamination leaks could be contained. In comparison to larger reactors having numerous components outside the reactor vessel, this feature increases the safety by decreasing the risks of an uncontained accident. Some SMR designs also envisage to install the reactor and the spent-fuel storage pools underground.<ref name=":14">{{Cite book |first=Nick |last=Cunningham |title=Small modular reactors: a possible path forward for nuclear power |date=2012 |publisher=American Security Project |oclc=813390081}}</ref>

Several molten salt reactors are being developed as SMRs, but they are not a new concept. Operational as research and test plants since the 1950s, molten salt reactors are now being touted as a clean and safe alternative to traditional water-cooled SMRs. One of the earliest molten salt reactor experiments was operated at Tennessee's Oak Ridge for four years, but shut down in 1969 after going critical. Even though the Molten Salt Reactor Experiment did end in a critical event, it was well known and respected throughout the nuclear research community as a success. However, later studies found the reactor only operated around 40 percent of the time, and experienced 171 unplanned shutdowns. These shutdowns were attributed to a number of technical problems, including: chronic pipe plugging, which led to charcoal beds designed to capture and remove radioactive materials; blower failures designed to remove reactor heat; and leaks within the freeze-valve safety system allowing fuel escapes. So far, modern metals have proven incapable of sustaining the natural corrosiveness of a small reactor's molten salt over a 4 year application.<ref>{{cite web |last1=Ramana |first1=M.V. |title=Molten salt reactors were trouble in the 1960s—and they remain trouble today |url=https://thebulletin.org/2022/06/molten-salt-reactors-were-trouble-in-the-1960s-and-they-remain-trouble-today/ |website=thebulletin.org |date=20 June 2022 |publisher=Bulletin of the Atomic Scientists |access-date=26 August 2025}}</ref> Concerning avoiding the risk of corrosion especially occurs and causes serious problem at thin-thickness wall of pipes in heat exchanger, new design named UNOMI has proposed which eliminates primary circuit existing outside of reactor vessel.<ref>{{Cite web|url=https://www.mdpi.com/2071-1050/4/10/2399|title=Recent Research of Thorium Molten-Salt Reactor from a Sustainability Viewpoint}}</ref> In this design, generated heat is removed from the surface of the reactor vessel instead of heat exchanger. As a result, available heat production will be limited to abote a few 10 MWth suitable for SMR.

Even Fluoride-Salt-Cooled High-Temperature Reactors (FHR) suffer from internal buildups of fission products, clogging cooling and safety systems. A method of reductive extraction can be used to catch buildups before they occur. This method removes the uranium fuel before the fission products. Unfortunately, the gas produced from the fluoride is highly corrosive and exposes plant metal to damage. As an alternative, nitrogen trifluoride is being proposed. However, ongoing research has not proven this to be a viable alternative and its efficacy is unclear.<ref>{{cite web |last1=Scheele |first1=Randall |title=Flibe Molten Salt Processing |url=https://www.energy.gov/ne/articles/flibe-molten-salt-processing |website=energy.gov |publisher=Flibe Energy, Inc. |access-date=31 August 2025}}</ref>

== Radioactive waste == New technology in nuclear waste recycling is promising safer and less expensive alternatives to today's methods. Known as partitioning and transmutation (P&T), this recycling and waste reducing process can reduce spent fuel to a smaller volume of waste with considerably less radiotoxicity.<ref>{{cite web |last1=Kooyman |first1=T. |title=Current state of partitioning and transmutation studies for advanced nuclear fuel cycles |url=https://www.sciencedirect.com/science/article/abs/pii/S0306454921001158 |website=sciencedirect.com |publisher=Science Direct |access-date=3 May 2026}}</ref>

A chemical separation process is used in P&T to extract plutonium and minor actinides. A specially designed reactor is then used to perform the transmutation of  transuranic elements (neptunium, plutonium, americium and curium). Fission is finally applied to safely destroy the remaining elements. P&T is believed to improve radioactive waste management due to the expected reduction in overall waste volume P&T creates.

Even highly enriched uranium reactors, applying shorter fuel cycle technologies, are now recycling major and minor actinides without the need for high purification schemes. The method is now used by LWR fast reactors in France, India, Japan and the Russian Federation. Their waste requires no plutonium separation from the other actinides. Pyroprocessing spent fuel is currently under development for LWR fast reactors and now operational in India, the Russian Federation and the European Union. Because SMR technology is so new, P&T has yet to be used on the spent fuel these plants will create. However, it is likely to be an important recycling method for most SMRs as this technology develops.<ref>{{cite web |last1=Bychkov |first1=Alexander V. |title=THE FUTURE: INNOVATIVE TECHNOLOGIES FOR RADIOACTIVE WASTE PROCESSING AND DISPOSAL |url=https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull55-3/55304622223.pdf |website=iaea.org |publisher=IAEA |access-date=27 August 2025}}</ref>

The back end of the nuclear fuel cycle for SMRs is a complex and contested issue that remains under debate.<ref name="IAEA2023"> {{cite report |title=Considerations for the Back End of the Fuel Cycle of Small Modular Reactors |publisher=International Atomic Energy Agency |series=IAEA-TECDOC-2040 |date=2023 |location=Vienna |url=https://www.iaea.org/publications/14708/considerations-for-the-back-end-of-the-fuel-cycle-of-small-modular-reactors |access-date=12 June 2025 }}</ref><ref name="Krall2022" /> The quantity and radiotoxicity of the radioactive waste produced by SMRs depend primarily on their design and the corresponding fuel cycle. Because SMRs encompass a broad spectrum of nuclear reactor types, there is no simple answer to this issue. SMRs may include small light water reactors of the third generation, as well as small fast neutron reactors of the fourth generation.

Some startup companies developing unconventional SMR prototypes often advocate waste reduction as a key advantage of their proposed solutions, and in some cases claim that their technology could eliminate the need for a deep geological repository to dispose of high-level and long-lived radioactive waste.<ref name="world-nuclear1"/><ref name="Krall2022"/> This is particularly true for companies developing fast neutron reactors of the fourth generation, such as molten salt reactors and metal-cooled reactors, including the sodium-cooled fast reactor and lead-cooled fast reactor.<ref name="OECD2021"> {{cite report |title=Advanced Reactors and Fuel Cycles |publisher=OECD Nuclear Energy Agency |date=2021 |url=https://www.oecd-nea.org/jcms/pl_21281/advanced-reactors-and-fuel-cycles |access-date=12 June 2025 }}</ref><ref name="IAEA2020"> {{cite report |title=Status of Small Reactor Designs Without On-Site Refuelling |publisher=International Atomic Energy Agency |series=IAEA Nuclear Energy Series No. NP-T-1.14 |date=2020 |location=Vienna |url=https://www.iaea.org/publications/14715/status-of-small-reactor-designs-without-on-site-refuelling |access-date=12 June 2025 }}</ref>

Fast breeder reactors "burn" {{chem|235|U|link=Uranium-235}} (0.7% of natural uranium) as fuel, but they also convert fertile materials such as {{chem|238|U|link=Uranium-238}} (which makes up 99.3% of natural uranium) into fissile {{chem|239|Pu|link=Plutonium-239}}. This newly produced plutonium can then be used as nuclear fuel.<ref name="world-nuclear1"/> The traveling wave reactor proposed by TerraPower is designed to "burn" the fuel it breeds in situ, without requiring its removal from the reactor core or further reprocessing.<ref>Wald, M. [http://www.technologyreview.com/energy/22114/?a=f "TR10: Traveling Wave Reactor"] {{Webarchive|url=https://web.archive.org/web/20111011040125/http://www.technologyreview.com/energy/22114/?a=f |date=11 October 2011 }}, [http://www.technologyreview.com ''Technology Review'']</ref>

Some SMR designs are based on the thorium fuel cycle, which is advocated by their promoters as a way to reduce the long-term radiotoxicity of waste compared to the uranium cycle.<ref name="WASH1097"> {{cite report |title=The Use of Thorium in Nuclear Power Reactors |series=WASH-1097 |section=5.3 |publisher=U.S. Atomic Energy Commission |date=May 1969 |url=http://www.energyfromthorium.com/pdf/WASH-1097.pdf }}</ref> However, the thorium cycle also presents significant operational challenges due to the production and use of {{chem|232|U|link=Uranium-232}} and the long-lived fertile {{chem|233|U|link=Uranium-233}}, both of which emit strong gamma rays. As a result, the presence of these radionuclides complicates the radiation shielding of fresh nuclear fuel and the long-term storage and disposal of their spent nuclear fuel.<ref name="WNA2024-Thorium"> {{cite web |title=Thorium |publisher=World Nuclear Association |date=May 2024 |url=https://world-nuclear.org/information-library/current-and-future-generation/thorium.aspx |access-date=12 June 2025 }}</ref><ref name="OECD2015-Thorium"> {{cite report |title=Introduction of Thorium in the Nuclear Fuel Cycle: Short- to Long-term Considerations |publisher=OECD Nuclear Energy Agency |date=2015 |url=https://www.oecd-nea.org/upload/docs/application/pdf/2020-11/7024-thorium.pdf |access-date=12 June 2025 }}</ref>

A 2022 study by Krall, Macfarlane and Ewing took a more critical approach, reporting that certain types of SMRs could produce more waste per unit of output power than conventional reactors—sometimes more than five times the amount of spent nuclear fuel per kilowatt, and up to thirty-five times more waste generated by neutron activation, such as activated steel and graphite.<ref name ="Barber2022">{{Cite magazine |last=Barber |first=Gregory |title=Smaller reactors may still have a big nuclear waste problem |language=en-US |magazine=Wired |url=https://www.wired.com/story/smaller-reactors-may-still-have-a-big-nuclear-waste-problem/ |access-date=3 August 2022 |issn=1059-1028}}</ref><ref name="Vaughan2022">{{Cite magazine |last=Vaughan |first=Adam |title=Mini nuclear power stations may produce more waste than large ones |website=New Scientist |date=30 May 2022 |url=https://www.newscientist.com/article/2322252-mini-nuclear-power-stations-may-produce-more-waste-than-large-ones/ |access-date=3 December 2023}}</ref><ref name="Stanford_University_2022">{{cite web |author=Stanford University |title=Small modular reactors produce high levels of nuclear waste |website=Stanford News |date=30 May 2022 |url=https://news.stanford.edu/2022/05/30/small-modular-reactors-produce-high-levels-nuclear-waste/#:~:text=%E2%80%9CWe%20found%20that%20small%20modular,%2C%20which%20will%20be%20expensive.%E2%80%9D |access-date=4 December 2023}}</ref><ref name="Krall2022">{{Cite journal |last1=Krall |first1=Lindsay M. |last2=Macfarlane |first2=Allison M. |last3=Ewing |first3=Rodney C. |date=7 June 2022 |title=Nuclear waste from small modular reactors |journal=Proceedings of the National Academy of Sciences |language=en |volume=119 |issue=23 |article-number=e2111833119 |doi=10.1073/pnas.2111833119 |doi-access=free |issn=0027-8424 |pmc=9191363 |pmid=35639689 |bibcode=2022PNAS..11911833K}}</ref> The authors identified neutron leakage as a primary issue for SMRs, as these reactors have a higher surface-area-to-volume ratio than conventional reactors. They calculated that, in smaller reactor cores, neutron leakage rates are significantly higher because emitted neutrons are less likely to interact with fissile atoms in the fuel and induce fission. Instead, more neutrons escape the core and are absorbed by materials used in neutron reflectors and shielding (thermal and gamma shields), rendering these materials radioactive waste through neutron activation.<ref name="Krall2022"/> Reactor designs using liquid metal coolants—such as molten sodium, lead, or lead-bismuth eutectic (LBE)—also become radioactive and contain activated impurities.<ref name="WNA2024-LMC"> {{cite web |title=Fast Neutron Reactors |publisher=World Nuclear Association |date=May 2024 |url=https://world-nuclear.org/information-library/current-and-future-generation/fast-neutron-reactors.aspx |access-date=12 June 2025 }}</ref>

Another issue pinpointed by Krall ''et al.'' (2022) related to higher neutron leakage in SMRs is that a lower fraction of their nuclear fuel is consumed, resulting in lower burnup and leaving more fissile material in their spent nuclear fuel, thereby increasing the waste volume. To sustain chain reactions in the smaller cores of SMRs, an alternative is to use nuclear fuel with a higher enrichment of {{chem|235|U|link=Uranium-235}}. This could increase the risks of nuclear proliferation and may require more stringent safeguard measures to prevent it (see also IAEA safeguards).<ref name="Krall2022"/>

If higher concentrations of fissile material remain in the spent fuel, the critical mass needed to sustain a nuclear chain reaction is also lower. As a direct consequence, the number of spent fuel assemblies present in a waste canister must also be lower, necessitating a larger number of canisters and overpacks (containment structures) to avoid criticality accidents and guarantee nuclear criticality safety in a deep geological repository.<ref>{{cite book |last1=Radin |first1=Alex |title=Monitored Retrieval Storage Review |date=1 November 1989 |publisher=Monitored Retrieval Storage Review Commission |location=Washington, DC |page=K-3 |quote=A secondary external enclosure for packaged spent fuel […].}}</ref> This also contributes to increased total waste volume and the number of disposal galleries needed in a geological repository.<ref name="WNA2024-BackEnd"> {{cite web |title=The Back End of the Nuclear Fuel Cycle |publisher=World Nuclear Association |date=May 2024 |url=https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-wastes/the-back-end-of-the-nuclear-fuel-cycle.aspx |access-date=12 June 2025 }}</ref>

Given the potential technical and economic importance of SMRs in providing zero-carbon electrical energy for climate change mitigation, as well as the long-term and social relevance of managing and disposing of radioactive waste without imposing a negative burden on future generations, the publication of Krall ''et al.'' (2022) in the prestigious PNAS journal has attracted numerous responses. These range from criticisms regarding the quality of their data and hypotheses<ref name="NeutronBytes2022">{{cite web |title=Stanford's questionable study on spent nuclear fuel for SMRs |website=Neutron Bytes |date=31 May 2022 |url=https://neutronbytes.com/2022/05/31/stanfords-questionable-study-on-spent-nuclear-fuel-for-smrs/ |access-date=3 December 2023}}</ref> to international debates on radioactive waste generated by SMRs and their decommissioning.<ref name="NEA2022">{{cite web |title=Management of spent fuel, radioactive waste and decommissioning in SMRs or advanced reactor technologies. 7-10 November 2022, Ottawa, Canada. Workshop programme |url=https://www.oecd-nea.org/upload/docs/application/pdf/2022-11/smr_programme_final.pdf |access-date=3 December 2023}}</ref>

In an interview with François Diaz-Maurin, the associate editor of the Bulletin of the Atomic Scientists, Lindsay Krall—the lead author of the study and a former MacArthur postdoctoral fellow at Stanford's Center for International Security and Cooperation (CISAC)—addressed questions and criticisms, including those raised by the NuScale reactor company.<ref name="Diaz-Maurin2022">{{cite web |last=Diaz-Maurin |first=François |title=Interview: Small modular reactors get a reality check about their waste |website=Bulletin of the Atomic Scientists |date=17 June 2022 |url=https://thebulletin.org/2022/06/interview-small-modular-reactors-get-a-reality-check-about-their-waste/ |access-date=3 December 2023}}</ref> One of Krall's main concerns in the interview was: {{blockquote |There's definitely a disconnect between the people working on the back end of the fuel cycle—especially with geologic repository development—and those actually designing reactors. And, there is not a lot of motivation for these reactor designers to think about the geologic disposal aspects because the NRC's new reactor design certification application does not have a chapter on geologic disposal...<ref name="Diaz-Maurin2022"/>}}

The high diversity of SMR reactors and their respective fuel cycles may also require more diverse waste management strategies to recycle or safely dispose of their nuclear waste.<ref name ="Barber2022"/><ref name="Krall2022"/> Managing a larger number of spent fuel types will be more challenging than the current situation, where most spent fuel comes from light water reactors.

As Krall and Macfarlane stressed in a 2018 paper, some types of SMR spent fuels or coolants—such as highly reactive and corrosive uranium fluoride ({{chem2|UF4}}) from molten salt reactors or pyrophoric sodium from liquid metal-cooled fast breeders—cannot be directly disposed of in a deep geologic repository because of their chemical reactivity in underground environments (such as deep clay formations, crystalline rocks, or rock salt). To avoid exacerbating spent fuel storage and disposal issues, it will be necessary to reprocess and condition these materials in an appropriate and safe manner before final geological disposal.<ref name="Krall_Macfarlane_2018">{{cite journal |first1=Lindsay M. |last1=Krall |first2=Allison M. |last2=Macfarlane |title=Burning waste or playing with fire? Waste management considerations for non-traditional reactors |journal=Bulletin of the Atomic Scientists |publisher=Routledge |date=31 August 2018 |volume=74 |issue=5 |pages=326–334 |url=https://www.tandfonline.com/doi/full/10.1080/00963402.2018.1507791 |access-date=3 December 2023 |doi=10.1080/00963402.2018.1507791 |bibcode=2018BuAtS..74e.326K |s2cid=149901270 |url-access=subscription}}</ref>

A study by Keto ''et al.'' (2022) at the VTT Technical Research Centre of Finland also addressed the management of spent nuclear fuel (SNF) and low- and intermediate-level waste (LILW) from the possible future deployment of SMRs in Finland. The study indicated that, per gigawatt-electric-year (GWe-year), larger masses of SNF and other high-level waste (HLW), as well as larger volumes of low-level waste (LLW), would be produced by a light water SMR compared to a large nuclear power plant.<ref name="Keto2022">{{cite report |last1=Keto |first1=Paula |last2=Juutilainen |first2=Pauli |last3=Schatz |first3=Timothy |last4=Naumer |first4=Sami |last5=Häkkinen |first5=Silja |title=Waste Management of Small Modular Nuclear Reactors in Finland |publisher=VTT Technical Research Centre of Finland |date=28 February 2022 |url=https://cris.vtt.fi/en/publications/waste-management-of-small-modular-nuclear-reactors-in-finland |access-date=15 December 2023}}</ref>

A report by the German Federal Office for the Safety of Nuclear Waste Management (BASE) found that extensive interim storage and fuel transports would still be required for SMRs. The report also concluded that a deep geological repository is unavoidable due to the presence of highly mobile, long-lived fission products that cannot be efficiently transmuted because of their low neutron cross section. This is the case with dose-dominating radionuclides such as {{chem|129|I|link=Iodine-129}}, {{chem|99|Tc|link=Technetium-99}}, and {{chem|79|Se|link=Selenium-79}}, which exist as soluble anions that are not sorbed onto the negatively charged minerals and are not retarded in geological media.<ref name=base_report/>

Nuclear waste is regulated within the existing nuclear governance systems, originally designed for conventional nuclear reactors. In the United States, oversight of waste is coordinated through the US Nuclear Regulatory Framework Commission and US Department of Energy. <ref name=":4">{{Cite journal |last1=Park |first1=Sulgiye |last2=Ewing |first2=Rodney C. |date=2023-11-13 |title=US Legal and Regulatory Framework for Nuclear Waste from Present and Future Reactors and Their Fuel Cycles |url=https://www.annualreviews.org/content/journals/10.1146/annurev-environ-112621-064435 |journal=Annual Review of Environment and Resources |volume=48 |pages=713–736 |doi=10.1146/annurev-environ-112621-064435}}</ref> SMRs produce broadly similar categories of waste as large reactors, however differences in deployment of scale, design, and use of SMR alters the transportation needs, logistics, and containment demands.<ref name=":4" />

== Nuclear proliferation == Nuclear proliferation, or the use of nuclear materials to create weapons, is a concern for small modular reactors. As SMRs have lower generation capacity and are physically smaller, they are intended to be deployed in many more locations than conventional plants.<ref name="auto1b2">{{Cite web |last=Trakimavičius |first=Lukas |date=Nov 2020 |title=Is Small Really Beautiful?The Future Role of Small Modular Nuclear Reactors (SMRs) In The Military |url=https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf |website=NATO Energy Security Centre of Excellence |language=en |access-date=5 December 2020 |archive-date=31 July 2022 |archive-url=https://web.archive.org/web/20220731034722/https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf }}</ref> SMRs are expected to substantially reduce staffing levels. The combination creates physical protection and security concerns.<ref name="areva-20100618">{{citation |last=Greneche |first=Dominique |title=Proliferation issues related to the deployment of Small & Medium Size reactors (SMRs) |date=18 June 2010 |url=http://bnrc.berkeley.edu/documents/forum-2010/Presentations/S-Session-III/Dominique_Greneche_NuclearConsulting_Pres.pdf |archive-url=https://web.archive.org/web/20170324173959/http://bnrc.berkeley.edu/documents/forum-2010/Presentations/S-Session-III/Dominique_Greneche_NuclearConsulting_Pres.pdf |archive-date=24 March 2017 |publisher=Areva |format=presentation}}</ref><ref name="nrc-201411052"/>

SMRs can be designed to use unconventional fuels allowing for higher burnup and longer fuel cycles.<ref name=":1" /> Longer refueling intervals could contribute to decrease the proliferation risks. Once the fuel has been irradiated, the mixture of fission products and fissile materials is highly radioactive and requires special handling, preventing casual theft.

Contrasting to conventional large reactors, SMRs can be adapted to be installed in a sealed underground chamber; therefore, "reducing the vulnerability of the reactor to a terrorist attack or a natural disaster".<ref name=":14"/> New SMR designs enhance the proliferation resistance, such as those from the reactor design company Gen4. These models of SMR offer a solution capable of operating sealed underground for the life of the reactor following installation.<ref name=":14" /><ref name="Ingersoll 2009 589–603"/>

Some SMR designs are designed for one-time fueling. This improves proliferation resistance by eliminating on-site nuclear fuel handling and means that the fuel can be sealed within the reactor. However, this design requires large amounts of fuel, which could make it a more attractive target. A 200 MWe 30-year core life light water SMR could contain about 2.5 tonnes of plutonium at end of life.<ref name="nrc-201411052" />

Furthermore, many SMRs offer the ability to go periods of greater than 10 years without requiring any form of refueling therefore improving the proliferation resistance as compared to conventional large reactors of which entail refueling every 18–24 months.<ref name=":14" />

Light-water reactors designed to run on thorium offer increased proliferation resistance compared to the conventional uranium cycle, though molten salt reactors have a substantial risk.<ref name="U-232 and the proliferation-resistance of U-233 in spent fuel2">{{Cite journal |last1=Kang |first1=J. |last2=Von Hippel |first2=F. N. |year=2001 |title=U-232 and the proliferation-resistance of U-233 in spent fuel |journal=Science & Global Security |volume=9 |issue=1 |pages=1–32 |bibcode=2001S&GS....9....1K |doi=10.1080/08929880108426485 |s2cid=8033110}} {{cite web |title=Kang & Von Hippel: U-232 etc... |url=http://www.torium.se/res/Documents/9_1kang.pdf |archive-url=https://web.archive.org/web/20141203135336/http://www.torium.se/res/Documents/9_1kang.pdf |archive-date=3 December 2014 |access-date=2 March 2015}}</ref><ref>{{Cite journal |last1=Ashley |first1=Stephen |year=2012 |title=Thorium fuel has risks |journal=Nature |volume=492 |issue=7427 |pages=31–33 |bibcode=2012Natur.492...31A |doi=10.1038/492031a |pmid=23222590 |s2cid=4414368 |doi-access=free}}</ref>

SMRs are transported from the factories without fuel, as they are fueled on the ultimate site, except some microreactors.<ref>{{cite web |author=Office of Nuclear Energy |url=https://www.energy.gov/ne/articles/what-nuclear-microreactor |title=What is a Nuclear Microreactor? |publisher=Office of Nuclear Energy |date= |access-date=18 August 2022}}</ref> This implies an independent transport of the fuel to the site and therefore increases the risk of nuclear proliferation. At the same time, millions of tons of nuclear waste are being shipped across the United States each year and there is no history of nuclear fuel or waste theft from these deliveries.

== Licensing process == Licensing is an essential process required to guarantee the safety, security and safeguards of a new nuclear installation.<ref name="3S_Risk_Analysis">{{cite conference |last1=Williams |first1=Adam David |last2=Osborn |first2=Douglas |last3=Cohn |first3=Brian |year=2019 |title=Security Safety and Safeguards (3S) risk analysis for small modular reactors |conference=INMM Annual Meeting |publisher=Sandia National Laboratory |osti=1640767 |url=https://www.osti.gov/biblio/1640767 |access-date=7 December 2023}}</ref> As of 2025, only NuScale Power's VOYGR, VOYGR-4, and VOYGR-6 SMRs are fully licensed for use in the United States.<ref>{{cite web |url=https://www.energy.gov/ne/articles/nrc-approves-first-us-small-modular-reactor-design |title=NRC Approves First U.S. Small Modular Reactor Design |date=2 September 2020 |website=energy.gov |publisher=Department of Energy |access-date=16 December 2023}}</ref> However, not all countries follow the NRC or IAEA licensing standards. In the United States and IAEA adhering countries, the licensing is based on a rigorous, independent analysis and reviewing work of all structures, systems and components critical for the nuclear safety under normal and accidental conditions on the whole service life of the installation including the long-term management of radioactive waste.<ref name="CNSC2016">{{cite web |title=DIS-16-04, Small Modular Reactors: Regulatory Strategy, Approaches and Challenges |website=Canadian Nuclear Safety Commission |date=30 May 2016 |url=https://nuclearsafety.gc.ca/eng/acts-and-regulations/consultation/comment/d-16-04/index.cfm |access-date=7 December 2023}}</ref> Licensing is based on the examination and scrutiny of the risk assessment studies and safety files elaborated by the fabricant and the exploitant of the SMR in the frame of the safety case they have to submit to the safety authority (regulatory body) when applying for a licence to construct and safely exploit the installation.<ref name="Pistner2021">{{cite report |last1=Pistner |first1=Christoph |last2=Englert |first2=Matthias |last3=Wealer |first3=Ben |last4=Hirschhausen |first4=Christian von |last5=Donderer |first5=Richard |title=Safety analysis and risk assessment of an application of SMR concepts (Small Modular Reactors) |publisher=Öko-Institut |date=1 March 2021 |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:52097919 |access-date=7 December 2023}}</ref> For NRC and IAEA licensing, the safety and feasibility cases of nuclear installations have to take into account all processes and elements important for the operational safety, its security (access protection), the nuclear safeguard (risk of proliferation), the proper conditioning of radioactive waste under a stable physico-chemical form, and the long-term safety related to the final disposal of the different types of radwaste produced, including all the waste produced during dismantling operations after decommissioning of the installation.<ref name="CNSC2016" /><ref name="STUK2020">{{cite web |author1=Ahonen, E. |author2=Heinonen, J. |author3=Lahtinen, N. |author4=Tuomainen, M. |author5= Lång, O. |year=2020 |title=Preconditions for the safe use of small modular reactors: Outlook for the licensing system (STUK, Finland) |url=https://www.julkari.fi/bitstream/handle/10024/139290/STUK_Preconditions%20for%20the%20safe%20use%20of%20small%20modular%20reactors.pdf?sequence=1&isAllowed=y |website=stuk.fi |access-date=7 December 2023}}</ref><ref name="WENRA2021">{{cite web |author=WENRA RHWG |date=12 January 2021 |title=Applicability of the safety objectives to SMRs |url=https://www.wenra.eu/sites/default/files/publications/WENRA_RHWG_Report_on_applicability_of_safety_objectivers_to_SMR.PDF |website=wenra.eu |access-date=7 December 2023}}</ref> A particularly important point of attention for the backend of the nuclear fuel cycle is to avoid to producing poorly conditioned waste, or waste types without sustainable final destination or susceptible to generating unexpected reprocessing and disposal costs.

The most common licensing process, applied by existing commercial reactors, is for the operation of light water reactors (PWR and BWR). Early designs for large-scale reactors date back to the 1960s and 1970s during the construction of the nuclear reactor fleet currently in service. Some adaptations of the original licensing process by the US's Nuclear Regulatory Commission (NRC) have been repurposed to better correspond to the specific characteristics and needs of the deployment of SMR units.<ref>{{Cite journal |last1=Sainati |first1=Tristano |last2=Locatelli |first2=Giorgio |last3=Brookes |first3=Naomi |date=15 March 2015 |title=Small Modular Reactors: Licensing constraints and the way forward |url=http://eprints.whiterose.ac.uk/91108/1/Accepted%20version.pdf |journal=Energy |volume=82 |pages=1092–1095 |doi=10.1016/j.energy.2014.12.079 |bibcode=2015Ene....82.1092S}}</ref> In particular, the US NRC process for licensing has focused mainly on conventional reactors. Design and safety specifications, human and organizational factors (including staffing requirements) have been developed for reactors with electrical output of more than 700 MWe.<ref>{{cite web |last1=Rysavy |first1=Charles F. |last2=Rhyne |first2=Stephen K. |last3=Shaw |first3=Roger P. |title=Small Modular Reactors |url=http://apps.americanbar.org/environ/committees/nuclearpower/docs/SMR-Dec_2009.pdf |website=American Bar Association |department=Special Committee on Nuclear Power, Section of Environment, Energy, and Resources |archive-url=https://web.archive.org/web/20160304194918/http://apps.americanbar.org/environ/committees/nuclearpower/docs/SMR-Dec_2009.pdf |archive-date=4 March 2016 |pages=1–3 |date=December 2009 }}</ref><ref>{{cite web |last1=Smith |first1=Tyson |department=Section of Environment, Energy, and Resources |title=Special Committee on Nuclear Power, Message From The Chair |url=http://apps.americanbar.org/dch/committee.cfm?com=NR601577 |website=American Bar Association |archive-url=https://web.archive.org/web/20120609132032/http://apps.americanbar.org/dch/committee.cfm?com=NR601577 |archive-date=9 June 2012 |date=25 May 2012 }}</ref>

To ensure adequate guidelines for the nuclear safety, while helping the licensing process, the IAEA has encouraged the creation of a central licensing system for SMRs.<ref>{{cite book |last=Black |first=R.L. |chapter=Licensing of small modular reactors (SMRs) |date=2015 |title=Handbook of Small Modular Nuclear Reactors |pages=279–292 |publisher=Elsevier |doi=10.1533/9780857098535.3.279 |isbn=978-0-85709-851-1 }}</ref> A workshop in October 2009 and another in June 2010 considered the topic, followed by an US congressional hearing in May 2010.

The NRC and the United States Department of Energy are working to define SMR licensing. The challenge of facilitating the development of SMRs is to prevent a weakening of the safety regulations: the risk of lightened regulations adopted more rapidly is to lower the safety characteristics of SMRs.<ref>{{Cite web |title=Advanced Small Modular Reactors (SMRs) |url=https://www.energy.gov/ne/nuclear-reactor-technologies/small-modular-nuclear-reactors |access-date=2 April 2019 |website=Energy.gov |language=en}}</ref><ref name="smallBeauty"/><ref name="UCS2013">{{cite web |title=Small modular nuclear reactors won't solve nuclear power's safety, security and cost problems, new report finds |website=Union of Concerned Scientists |date=26 September 2013 |url=https://www.ucsusa.org/about/news/nuclear-powers-safety-security-and-cost-problems |access-date=27 December 2023}}</ref> While deploying identical systems built in manufacturing plants with an improved quality control can be considered an advantage, SMRs remain nuclear reactors with a very high energy density and their smaller size is not ''per se'' an intrinsic guarantee for a better safety. Any severe accident with external radioactive contamination release could have potential serious consequences not so different from that of a large LWR reactor. It would also probably signify the final rejection of nuclear energy by the public and the end of the nuclear industry. The potential "proliferation" of large SMR fleets and the high diversity of their design also complicate the licensing process. The nuclear safety cannot be sacrificed for industrial or economical interests and the risk of nuclear accident increases with the number of reactors in service, small or large unit.

The US Advanced Reactor Demonstration Program was expected to help license and build two prototype SMRs during the 2020s, with up to $4 billion of government funding.<ref name="science-202005202">{{cite news |last=Cho |first=Adrian |date=20 May 2020 |title=U.S. Department of Energy rushes to build advanced new nuclear reactors |magazine=Science |url=https://www.science.org/content/article/us-department-energy-rushes-build-advanced-new-nuclear-reactors |access-date=21 May 2020}}</ref>

In July 2024, the ADVANCE Act directed the US NRC to develop a process to license and regulate microreactor designs. The Act is intended to expedite the deployment of microreactors, among other nuclear technologies.<ref name="Goff">{{Cite web |last=Goff |first=Michael |date=10 July 2024 |title=Newly Signed Bill Will Boost Nuclear Reactor Deployment in the United States |url=https://www.energy.gov/ne/articles/newly-signed-bill-will-boost-nuclear-reactor-deployment-united-states |access-date=14 July 2024 |website=Energy.gov |language=en}}</ref>

== Flexibility == Small nuclear reactors, in comparison to conventional nuclear power plants, offer potential advantages related to the flexibility of their modular construction.<ref name=":14"/> It would be possible to incrementally connect additional units to the grid in the event electrical load increases. Additionally, this flexibility in a standardized SMRs design revolving around modularity could allow for a faster production at a decreasing cost following the completion of the first reactor on site.<ref name=":14"/><ref name="Ingersoll 2009 589–603">{{Cite journal |last=Ingersoll |first=D.T. |date=2009 |title=Deliberately small reactors and the second nuclear era |journal=Progress in Nuclear Energy |volume=51 |issue=4–5 |pages=589–603 |doi=10.1016/j.pnucene.2009.01.003 |bibcode=2009PNuE...51..589I |issn=0149-1970 }}</ref>

The hypothesized flexibility and modularity of SMR is intended to allow additional power generation capability to be installed at existing power plants. A site could host several SMRs, one going off-line for refueling while the other reactors stay online as it is presently already the case for conventional larger reactors.<ref name=":14"/>

SMRs operating in hybrid energy systems combining with renewables can develop multipurpose configurations developing system-level efficiency in sectors difficult to electrify.<ref name=":5">{{Cite journal |last1=Aliko |first1=Erald |last2=Emblemsvåg |date=Jan 2025 |title=Reviewing the Possible Role of Nuclear Power in Hybrid Energy Systems for Sustainable Development |journal=International Journal of Energy Research |issue=1 |article-number=9948447 |doi=10.1155/er/9948447 |doi-access=free |bibcode=2025IJER.202548447A }}</ref>

Hybrid system integration of SMRs without needed electrical generation foresees the direct use of thermal energy in co-generation. This includes desalination, district heating, industrial heating, industrial processes, and hydrogen production.<ref>{{Cite journal |date=2024 |title=Small Modular Reactors: Advances in SMR Developments 2024 |url=http://www.iaea.org/publications/15790/small-modular-reactors-advances-in-smr-developments-2024 |website=iaea |doi=10.61092/iaea.3o4h-svum }}</ref>

Flexibility of SMRs enable nuclear energy use within broader energy system integration, and expanding emission reduction goals to varying degrees. <ref name=":5" />

SMRs have been proposed for micro-grids in remote regions; flexibility of SMR allows for base-load generation, adjusting output from a response to demand. Complimenting wind and solar power intermittently.<ref name=":6">{{Cite journal |last1=Michaelson |first1=D |last2=Jiang |first2=J |date=Dec 1, 2021 |title=Review of integration of small modular reactors in renewable energy microgrids |url=https://www.sciencedirect.com/science/article/pii/S1364032121009138 |journal=Renewable and Sustainable Energy Reviews |volume=152 |article-number=111638 |doi=10.1016/j.rser.2021.111638 |bibcode=2021RSERv.15211638M }}</ref> SMRs enhancing resilience in geographically isolated communities.<ref name=":6" />

When electrical energy is not needed, some SMR designs foresee the direct use of thermal energy, minimizing so the energy loss. This includes "desalination, industrial processes, hydrogen production, shale oil recovery, and district heating", uses for which the present conventional larger reactors are not designed.<ref name=":14"/><ref name="Cogeneration2" />

== Economics == [[File:Diagram of a NuScale reactor.jpg|thumb|A diagram of the early NuScale Power Module reactor (50 MWe) in 2022.<ref>{{cite web |title=NRC Certifies First U.S. Small Modular Reactor Design |url=https://www.energy.gov/ne/articles/nrc-certifies-first-us-small-modular-reactor-design |website=energy.gov |publisher=DOE |access-date=12 June 2025}}</ref> The module was the first in the US to be NRC approved. NuScale upgraded the Power Module output to 77 MWe and received NRC approval for its use in the VOYGR-4 (308 MWe) and the VOYGR-6 (462 MWe) in May 2025.<ref>{{cite web |title=NuScale Power's Small Modular Reactor (SMR) Achieves Standard Approval From US NRC For 77 MWe |url=https://www.nuscalepower.com/press-releases/2025/nuscale-powers-small-modular-reactor-smr-achieves-standard-design-approval-from-us-nuclear-regulatory-commission-for-77-mwe |website=nuscalepower.com |publisher=NuScale Power |access-date=12 June 2025}}</ref>]] A SMR factory would require substantial upfront capital. Per-unit costs would only become economical when an estimated 40–70 units are produced.<ref>{{cite news |last1=Harrabin |first1=Roger |date=23 March 2016 |title=The nuclear industry: a small revolution |work=BBC News |publisher=British Broadcasting Corporation |url=https://www.bbc.co.uk/news/business-35863846 |access-date=3 April 2016}}</ref><ref name="sciencedirect.com">{{Cite journal |last1=Mignacca |first1=Benito |last2=Locatelli |first2=Giorgio |last3=Sainati |first3=Tristano |date=20 June 2020 |title=Deeds not words: Barriers and remedies for Small Modular nuclear Reactors |journal=Energy |volume=206 |article-number=118137 |doi=10.1016/j.energy.2020.118137 |doi-access=free |bibcode=2020Ene...20618137M |hdl=11311/1204935 |hdl-access=free}}</ref>

Another potential advantage is that a future power station using SMRs can begin with a single module and expand by adding modules as demand grows. This reduces startup costs associated with conventional designs.<ref name="Mignacca2" /> Some SMRs also have a load-following design such that they could produce less electricity when demand is low.

According to a 2014 study of electricity production in decentralized microgrids, the total cost of using SMRs for electricity generation would be significantly lower compared to the total cost of offshore wind power, solar thermal energy, biomass, and solar photovoltaic electricity generation plants.<ref name=":03">{{Cite journal |last1=Islam |first1=Md. Razibul |last2=Gabbar |first2=Hossam A. |date=6 June 2014 |title=Study of small modular reactors in modern microgrids |journal=International Transactions on Electrical Energy Systems |volume=25 |issue=9 |pages=1943–1951 |doi=10.1002/etep.1945 |issn=2050-7038 |doi-access=free}}</ref>

Construction costs per SMR reactor were claimed in 2016 to be less than that for a conventional nuclear plant, while exploitation costs might be higher for SMRs due to low scale economics and the higher number of reactors. SMR staff operating costs per unit output can be as much as 190% higher than the fixed operating cost of fewer large reactors.<ref name="eysmr-2016032">{{cite report |url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/665300/TEA_Projects_5-7_-_SMR_Cost_Reduction_Study.pdf |title=Small modular reactors - Can building nuclear power become more cost-effective? |date=March 2016 |publisher=gov.uk |page=38 |access-date=29 February 2020 |work=Ernst & Young}}</ref> Modular building is a very complex process and there is "extremely limited information about SMR modules transportation", according to a 2019 report.<ref name="transportation2"/>

A production cost calculation done by the German Federal Office for the Safety of Nuclear Waste Management (BASE), taking into account economies of scale and learning effects from the nuclear industry, suggests that an average of 3,000 SMR would have to be produced before SMR production would be worthwhile. This is because the construction costs of SMRs are relatively higher than those of large nuclear power plants due to the low electrical output.<ref name="base_report" />

In 2017, an Energy Innovation Reform Project (EIRP) study of eight companies looked at reactor designs with capacity between 47.5 MWe and 1,648 MWe.<ref>{{Cite web |last=EIRP |date=1 July 2017 |title=What Will Advanced Nuclear Power Plants Cost? |url=https://www.innovationreform.org/2017/07/01/will-advanced-nuclear-power-plants-cost/ |access-date=3 November 2020 |website=Energy Innovation Reform Project |language=en-US |archive-date=16 April 2022 |archive-url=https://web.archive.org/web/20220416045124/https://www.innovationreform.org/2017/07/01/will-advanced-nuclear-power-plants-cost/ }}</ref> The study reported average capital cost of $3,782/kW, average operating cost total of $21/MWh and levelized cost of electricity (LCOE) of $60/MWh.

In 2020, Energy Impact Center founder Bret Kugelmass claimed that thousands of SMRs could be built in parallel, "thus reducing costs associated with long borrowing times for prolonged construction schedules and reducing risk premiums currently linked to large projects".<ref name="reutersevents.com2">{{cite news |url=https://www.reutersevents.com/nuclear/industry-heads-warn-nuclear-costs-must-be-slashed |title=Industry heads warn nuclear costs must be slashed |last=Day |first=Paul |publisher=Reuters |date=21 July 2020 |access-date=25 January 2023}}</ref> GE Vernova Hitachi Nuclear Energy Executive Vice President Jon Ball agreed, saying the modular elements of SMRs would also help reduce costs associated with extended construction times.<ref name="reutersevents.com2" />

In October 2023, an academic paper published in ''Energy'' collated the basic economic data of 19 more developed SMR designs, and modeled their costs in a consistent manner. A Monte Carlo simulation showed that none were profitable or economically competitive. For the closer to market PWR SMRs the median LCOEs ranged from $218/MWh to $614/MWh (in 2020 US dollars), with lower first quartile estimates from $188/MWh to $385/MWh. The three high-temperature gas-cooled reactor designs, which needed more development time, had lower median LCOEs from $116/MWh to $137/MWh.<ref name=steigerwald-20231015>{{cite journal |doi=10.1016/j.energy.2023.128204 |title=Uncertainties in estimating production costs of future nuclear technologies: A model-based analysis of small modular reactors |last1=Steigerwald |first1=Björn |last2=Weibezahn |first2=Jens |last3=Slowik |first3=Martin |last4=von Hirschhausen |first4=Christian |journal=Energy |publisher=Elsevier |volume=281 |issue=15 |date=15 October 2023 |article-number=128204 |doi-access=free |bibcode=2023Ene...28128204S}}</ref>

The first SMR deployment project in the US was the Carbon Free Power Project, which planned to deploy six 77 MWe NuScale reactors, reduced from twelve in earlier plans. Estimated target electricity generation price after subsidies was $89/MWh in 2023, an increase from $58/MWh in 2021. The increased generation cost led to the decision to cancel the project in November 2023.<ref name=eenews-20231109 /> Before its cancellation, the project received a $1.355 billion cost-share award toward construction costs from the US government in 2020<ref name=wnn-20201019>{{cite news |url=https://www.world-nuclear-news.org/Articles/US-government-backs-NuScale-projects-at-home-and-a |title=US government backs NuScale projects at home and abroad |publisher=World Nuclear News |date=19 October 2020 |access-date=10 January 2023}}</ref> plus an estimated $30/MWh generation subsidy from the Inflation Reduction Act of 2022.<ref name=wnn-20230109>{{cite news |date=9 January 2023 |title=Further cost refinements announced for first US SMR plant |publisher=World Nuclear News |url=https://www.world-nuclear-news.org/Articles/Further-cost-refinements-announced-for-first-US-SM |access-date=10 January 2023}}</ref> Unsubsidized cost estimates at cancellation were a capital cost of $20,139/kW and generating cost of $119/MWe.<ref name=ieefa-20230111>{{cite web |url=https://ieefa.org/resources/eye-popping-new-cost-estimates-released-nuscale-small-modular-reactor |title=Eye-popping new cost estimates released for NuScale small modular reactor |last=Schlissel |first=David |website=Institute for Energy Economics & Financial Analysis |author-link=David A. Schlissel |date=11 January 2023 |access-date=27 January 2023}}</ref> This raised concerns about the commercial prospects in the US of the other SMR designs.<ref name=science-20231110>{{cite news |url=https://www.science.org/content/article/deal-build-pint-size-nuclear-reactors-canceled |title=Deal to build pint-size nuclear reactors canceled |last=Cho |first=Adrian |magazine=Science |date=10 November 2023 |access-date=11 November 2023}}</ref>

In 2024, Australian scientific research body CSIRO estimated that electricity produced in Australia by a SMR constructed from 2023 would cost roughly 2.5 times that produced by a traditional large nuclear plant, falling to about 1.6 times by 2030.<ref name=wnn-20240522>{{cite news |url=https://www.world-nuclear-news.org/Articles/Large-scale-nuclear-included-in-Australian-cost-re |title=Large-scale nuclear included in Australian cost report |website=World Nuclear News |date=22 May 2024 |access-date=23 May 2024}}</ref><ref name=csiro-202405>{{cite web |url=https://www.csiro.au/-/media/Energy/GenCost/GenCost2023-24Final_20240522.pdf |title=GenCost 2023-24 |last1=Graham |first1=Paul |last2=Hayward |first2=Jenny |last3=Foster |first3=James |website=Commonwealth Scientific and Industrial Research Organisation |pages=xii,30–33, 50–52, 90 |date=May 2024 |access-date=22 May 2024}}</ref>

The final investment decision in 2025 to proceed with the build of a BWRX-300 SMR in Canada was based on a forecast cost of CA$7.7 billion (US$5.6 billion), with an estimated cost of CA$13.2 billion (US$9.6 billion) for three further units. These costs include finance charges and some contingency.<ref name=wnn-20250523>{{cite news |url=https://www.world-nuclear-news.org/articles/what-is-the-budget-for-canadas-first-smr-project |title=Canada's first SMR project: How is CAD20.9 billion cost calculated? |website=World Nuclear News |date=23 May 2025 |access-date=4 June 2025}}</ref>

== List of reactor designs == {{Main|List of small modular reactor designs}} Numerous reactor designs have been proposed. Notable SMR designs:

{{trim|{{#section-h::List of small nuclear reactor designs|Summary table}}}}

== Siting/infrastructure == SMRs are expected to require less land, e.g., the 470 MWe 3-loop Rolls-Royce SMR reactor should take {{Convert|40000|m2|abbr=on}}, 10% of that needed for a traditional plant.<ref name="rollsroyce-smr-brochure-2017">{{cite report |url=https://www.rolls-royce.com/~/media/Files/R/Rolls-Royce/documents/customers/nuclear/smr-brochure-july-2017.pdf |title=Small Modular Reactors UK, promotion brochure |publisher=Rolls-Royce |year=2017}} (5.5 MB)</ref> This unit is too large to meet the International Atomic Energy Agency's definition of a SMR being smaller than 300MWe<ref name="iaea-smr-definition">{{cite web |url=https://www.iaea.org/newscenter/news/what-are-small-modular-reactors-smrs |title=What are Small Modular Reactors (SMRs)? |website=iaea.org |date=13 September 2023 |access-date=20 February 2024}}</ref> and will require more on-site construction, which calls into question the claimed benefits of SMRs. The firm is targeting a 500-day construction time.<ref name="rollsroyce-2017">{{cite report |url=https://www.rolls-royce.com/~/media/Files/R/Rolls-Royce/documents/customers/nuclear/smr-technical-summary.pdf |archive-url=https://web.archive.org/web/20190608143016if_/https://www.rolls-royce.com/~/media/Files/R/Rolls-Royce/documents/customers/nuclear/smr-technical-summary.pdf |archive-date=8 June 2019 |title=UK SMR – brochure with specifications |publisher=Rolls-Royce |year=2017}} (5 MB) Archived</ref>

Electricity needs in remote locations are usually small and variable, making them suitable for a smaller plant.<ref name="Report to Congress"/>{{rp|8}} The smaller size may also reduce the need to access to a large grid to distribute their output.

== Proposed sites == === Argentina === In February 2014, the CAREM SMR project started in Argentina with the civil engineering construction of the containment building of a prototype reactor. The CAREM acronym means {{lang|es|Central ARgentina de Elementos Modulares}}. The National Atomic Energy Commission ({{langx|es|Comisión Nacional de Energía Atómica}}, CNEA), the Argentine government agency in charge of nuclear energy research and development and {{ill|Nucleoeléctrica Argentina|es|Nucleoelectrica Argentina SA}}, the national nuclear energy company, are cooperating to achieve the realization of the project.<ref name="WorldNuclearNews2023">{{cite web |title=CNEA and Nucleoeléctrica sign CAREM SMR agreement: New Nuclear |website=World Nuclear News |date=30 October 2023 |url=https://www.world-nuclear-news.org/Articles/Argentina-s-SMR-CNEA-and-Nucleoelectrica-sign-agre#:~:text=The%20CAREM%20name%20is%20taken,be%20sourced%20from%20Argentine%20companies. |access-date=14 December 2023}}</ref>

CAREM-25 is a prototype of 25 MWe, the first nuclear power plant completely designed and developed in Argentina.<ref name="WorldNuclearNews2023" /> The project was suspended several times before being resumed. In October 2022, CNEA expected that the civil construction works would be finished by 2024. If construction continues according to plan, the first criticality of CAREM-25 is foreseen by the end of 2027.<ref name="WorldNuclearNews2023" />

=== Canada === In 2018, the Canadian province of New Brunswick announced it would invest $10 million for a demonstration project at the Point Lepreau Nuclear Generating Station.<ref>{{Cite web |last=Government of New Brunswick |first=Canada |date=26 June 2018 |title=$10 million committed for nuclear research cluster |url=https://www2.gnb.ca/content/gnb/en/news/news_release.2018.06.0832.html |website=www2.gnb.ca}}</ref> It was later announced that SMR proponents Advanced Reactor Concepts<ref>{{Cite web |last=Government of New Brunswick |first=Canada |date=9 July 2018 |title=Partner announced in nuclear research cluster |url=https://www2.gnb.ca/content/gnb/en/departments/erd/news/news_release.2018.07.0906.html |website=www2.gnb.ca}}</ref> and Moltex<ref>{{Cite web |last=Government of New Brunswick |first=Canada |date=13 July 2018 |title=Moltex to partner in nuclear research and innovation cluster |url=https://www2.gnb.ca/content/gnb/en/departments/erd/news/news_release.2018.07.0930.html |website=www2.gnb.ca}}</ref> would open offices there. One unit is scheduled for construction at Point Lepreau Nuclear Generating Station, Canada, in July 2018. Both Moltex and ARC Nuclear are vying for the contract.<ref>{{Cite web |url=https://atlantic.ctvnews.ca/n-b-makes-step-forward-on-second-nuclear-reactor-at-point-lepreau-1.4722810 |archive-url=https://web.archive.org/web/20191210062438/https://atlantic.ctvnews.ca/n-b-makes-step-forward-on-second-nuclear-reactor-at-point-lepreau-1.4722810 |archive-date=10 December 2019 |title=N.B. makes step forward on second nuclear reactor at Point Lepreau |date=9 December 2019 |website=Atlantic |language=en |access-date=19 January 2020}}</ref>

On 1 December 2019, the Premiers of Ontario, New Brunswick and Saskatchewan signed a memorandum of understanding (MoU) <ref>{{cite web |title=Collaboration memorandum of understanding |url=http://files.news.ontario.ca.s3-website-us-east-1.amazonaws.com/opo/en/learnmore/premier_ford_premier_higgs_and_premier_moe_sign_agreement_on_the_development_of_small_modular_reacto/2019%2011%2027%20-%20MOU%20Prov%20NB%20and%20ON%20and%20SK.pdf?_ga=2.103085056.1434873882.1575249250-931592757.1575249250 |access-date=2 December 2019 |publisher=Government of Ontario}}</ref> "committing to collaborate on the development and deployment of innovative, versatile and scalable nuclear reactors, known as Small Modular Reactors (SMRs)."<ref>{{cite web |title=Premier Ford, Premier Higgs and Premier Moe Sign Agreement on the Development of Small Modular Reactors |url=https://news.ontario.ca/opo/en/2019/12/premier-ford-premier-higgs-and-premier-moe-sign-agreement-on-the-development-of-small-modular-reacto.html |access-date=2 December 2019 |website=ontario.ca |publisher=Government of Ontario}}</ref> They were joined by Alberta in August 2020.<ref>{{Cite web |title=Opinion: Small nuclear reactors can play big role in clean energy transition |url=https://calgaryherald.com/opinion/columnists/opinion-small-nuclear-reactors-can-play-big-role-in-clean-energy-transition |website=calgaryherald}}</ref> Continued support from citizens and government officials has led to the execution of a selected SMR at the Canadian Nuclear Laboratory.<ref name=":24"/>

In 2021, Ontario Power Generation announced they plan to build a BWRX-300 SMR at their Darlington site to be completed by 2028. A licence for construction still had to be applied for.<ref>[https://world-nuclear-news.org/Articles/OPG-chooses-BWRX-300-SMR-for-Darlington-new-build ''OPG chooses BWRX-300 SMR for Darlington new build.''] WNN, 2 December 2021</ref>

On 11 August 2022, Invest Alberta, the Government of Alberta's crown corporation signed a MoU with Terrestrial Energy regarding IMSR in Western Canada through an interprovincial MoU it joined earlier.<ref>{{cite web |title=Pact signed to advance IMSR development in western Canada |url=https://www.ans.org/news/article-4221/pact-signed-to-advance-imsr-development-in-western-canada/ |access-date=18 August 2022 |publisher=NuclearNewswire}}</ref>

=== China === In July 2019, China National Nuclear Corporation (CNNC) announced it would build an ACP100 SMR on the north-west side of the existing Changjiang Nuclear Power Plant at Changjiang, in the Hainan province by the end of the year.<ref name=wnn-20190722>{{cite news |url=http://www.world-nuclear-news.org/Articles/CNNC-launches-demonstration-SMR-project |title=''CNNC launches demonstration SMR project'' |publisher=World Nuclear News |date=22 July 2019}}</ref> On 7 June 2021, the demonstration project, named the Linglong One, was approved by China's National Development and Reform Commission.<ref>{{Cite web |title=''China approves construction of demonstration SMR: New Nuclear - World Nuclear News'' |url=https://world-nuclear-news.org/Articles/Construction-of-demonstration-Chinese-SMR-approved |access-date=13 July 2021 |website=world-nuclear-news.org |date=7 June 2021 }}</ref> In July, CNNC started construction,<ref>{{Cite news |author=Editing staff |date=13 July 2021 |title=''China launches first commercial onshore small reactor project'' |language=en |work=Reuters |url=https://www.reuters.com/article/us-china-nuclearpower-idUSKBN2EJ073}}</ref> and in October 2021, the containment vessel bottom of the first of two units was installed. It is the world's first commercial land-based SMR prototype.<ref name="containment-linglong1">[https://www.world-nuclear-news.org/Articles/Installation-of-containment-starts-at-Chinese-SMR ''Installation of containment starts at Chinese SMR.''] WNN, 25 October 2021</ref>

In August 2023, the core module was installed. The core module includes an integrated pressure vessel, steam generator, primary pump receiver. The reactor's planned capacity is 125 MWe.<ref>{{Cite web |last=Largue |first=Pamela |date=11 August 2023 |title=Core module instaled at China's Linglong One modular reactor |url=https://www.powerengineeringint.com/nuclear/reactors/core-module-instaled-at-chinas-linglong-one-modular-reactor/ |access-date=13 August 2023 |website=Power Engineering International |language=en-US}}</ref>

=== France === At the beginning of 2023, Électricité de France (EDF) created a new subsidiary to develop and construct a new SMR named Nuward. It was a 340 MWe design with two independent light water reactors of 170 MWe. The twin reactors were sheltered in a single containment building sharing most of their equipment.<ref name="EDF2022">{{cite web |author=EDF |title=NUWARD SMR, leading the way to a low‑carbon world |website=EDF.fr |date=16 December 2022 |url=https://www.edf.fr/en/the-edf-group/producing-a-climate-friendly-energy/nuclear-energy/shaping-the-future-of-nuclear/the-nuwardtm-smr-solution/the-solution |access-date=14 December 2023}}</ref> In August 2023, EDF submitted a safety case for Nuward to the {{lang|fr|autorité de sûreté nucléaire}} (ASN), the French safety authority.<ref name="Lopez2023">{{cite web |last1=Lopez |first1=Alicia |title=Licensing process begins for Nuward Small Modular Reactor project in France |website=Foro Nuclear |date=10 August 2023 |url=https://www.foronuclear.org/en/updates/news/licensing-process-begins-for-nuward-small-modular-reactor-project-in-france/ |access-date=14 December 2023}}</ref>

In July 2024, EDF announced it was discontinuing the existing design process for Nuward, and will work on an SMR design based on existing rather than innovative technologies, following discussions with prospective SMR customers.<ref name=nei-20240704>{{cite news |url=https://www.neimagazine.com/news/edf-abandons-nuward-smr-design-in-favour-of-established-technologies/ |title=EDF rethink on Nuward SMR design in favour of established technologies |publisher=Nuclear Engineering International |date=4 July 2024 |access-date=16 July 2024}}</ref><ref name=nei-20240711>{{cite news |url=https://www.neimagazine.com/news/edf-pulls-out-of-uk-smr-competition-geh-rolls-royce-holtec-and-nuscale-submit-tenders/ |title=EDF pulls out of UK SMR competition; GEH, Rolls-Royce, Holtec and NuScale submit tenders |publisher=Nuclear Engineering International |date=11 July 2024 |access-date=16 July 2024}}</ref> In January 2025, EDF announced that the new Nuward conceptual design would be completed by mid-2026 to come to market in the 2030s, with an output of about 400 MWe and usable heat output of 100 MWt.<ref name=wnn-20250107>{{cite news |url=https://www.world-nuclear-news.org/articles/edf-simplifies-nuward-smr-design |title=EDF simplifies Nuward SMR design |website=World Nuclear News |date=7 January 2025 |access-date=19 January 2025}}</ref>

=== Poland === Polish chemical company Synthos declared plans to deploy a Hitachi BWRX-300 reactor (300 MW) in Poland by 2030.<ref>{{Cite web |url=https://www.thefirstnews.com/article/billionaire-pole-to-build-nuclear-reactor-8244 |title=Billionaire Pole to build nuclear reactor |website=www.thefirstnews.com |language=en |access-date=17 February 2020}}</ref> A feasibility study was completed in December 2020 and the licensing process started with the Polish National Atomic Energy Agency.<ref>{{Cite web |title=Feasibility study completed on SMRs for Poland - Nuclear Engineering International |url=https://www.neimagazine.com/news/newsfeasibility-study-completed-on-smrs-for-poland-8415956 |access-date=4 January 2021 |website=www.neimagazine.com |date=18 December 2020}}</ref>

In February 2022, NuScale Power and the large mining conglomerate KGHM Polska Miedź announced signing of contract to construct a first operational reactor in Poland by 2029.<ref>{{Cite web |date=February 2022 |title=NuScale, KGHM agree to deploy SMRs in Poland |language=en |url=https://www.world-nuclear-news.org/Articles/NuScale,-KGHM-agree-to-deploy-SMRs-in-Poland}}</ref>

=== Romania === On the occasion of 2021 United Nations Climate Change Conference, the state-owned Romanian nuclear energy company Nuclearelectrica and NuScale Power signed an agreement to build a power plant with six small-scale nuclear reactors at the Doicești power station, on the site of a former coal power plant, located near the village of Doicești, Dâmbovița county, 90 km North of Bucharest. The project is estimated to be completed by 2026–2027, which will make the power plant the first of its kind in Europe. The power plant is expected to generate 462 MWe, securing the consumption of about 46.000 households and would help to avoid the release of 4 million tons of {{CO2}} per year.<ref>{{Cite web |last=Chirileasa |first=Andrei |date=24 May 2022 |title=Romania, the US agree on location of first small-scale nuclear reactor |url=https://www.romania-insider.com/ro-us-location-small-scale-reactor-may-2022 |access-date=22 November 2022 |website=Romania Insider}}</ref><ref>{{Cite news |title=Prima centrală cu mini reactor nuclear din Europa va fi la Doicești, Dâmbovi��a. Cum funcționează o centrală SMR |url=https://romania.europalibera.org/a/centrala-nculeara-doicesti/31917155.html |access-date=22 November 2022 |website=Europa Liberă România |date=28 June 2022 |language=ro |last1=Despa |first1=Oana}}</ref><ref>{{Cite web |last=Agerpres |title=Ghiţă (Nuclearelectrica): Suntem încrezători în potenţialul pe care amplasamentul de la.. |url=http://www.agerpres.ro/economic/2022/06/15/ghita-nuclearelectrica-suntem-increzatori-in-potentialul-pe-care-amplasamentul-de-la-doicesti-il-are-de-a-gazdui-primul-smr-nuscale-din-europa--934792 |access-date=22 November 2022 |website=www.agerpres.ro |language=ro}}</ref>

=== Russia === Russia has started to deploy on its arctic coast small nuclear reactors embarked on board icebreakers. In May 2020, the first prototype of a floating nuclear power plant with two 30 MWe reactors – the type ''KLT-40'' – started operation in Pevek, Russia.<ref name="klt-40_pris" /> This concept is based on the design of nuclear icebreakers.<ref name="klt40" />

=== United Kingdom === In 2016, it was reported that the UK Government was assessing Welsh SMR sites – including the former Trawsfynydd nuclear power station – and on the site of former nuclear or coal-fired power stations in Northern England. Existing nuclear sites including Bradwell, Hartlepool, Heysham, Oldbury, Sizewell, Sellafield, and Wylfa were stated to be possibilities.<ref>{{cite news |last1=McCann |first1=Kate |title=Mini nuclear power stations in UK towns move one step closer |url=https://www.telegraph.co.uk/news/2016/04/02/mini-nuclear-power-stations-in-uk-towns-move-one-step-closer/ |access-date=3 April 2016 |work=The Sunday Telegraph |date=2 April 2016}}</ref> The target cost for a 470 MWe Rolls-Royce SMR unit is £1.8 billion for the fifth unit built.<ref name=wnn-20191107>{{cite news |url=http://www.world-nuclear-news.org/Articles/UK-confirms-funding-for-Rolls-Royce-SMR |title=UK confirms funding for Rolls-Royce SMR |publisher=World Nuclear News |date=7 November 2019 |access-date=8 November 2019}}</ref><ref name=rr-20210908>{{cite web |url=https://www.nuclearuniversities.ac.uk/wp-content/uploads/2021/09/Sophie-Macfarlane-Smith.pdf |title=Rolls-Royce SMR - Nuclear Academics Meeting |last=Macfarlane-Smith |first=Sophie |website=Rolls-Royce |date=8 September 2021 |access-date=25 September 2021}}</ref> In 2020, it was reported that Rolls-Royce had plans to construct up to 16 SMRs in the UK. In 2019, the company received £18 million to begin designing the modular system.<ref>{{cite news |title=Rolls-Royce plans 16 mini-nuclear plants for UK |url=https://www.bbc.co.uk/news/science-environment-54703204 |access-date=12 November 2020 |work=BBC News |date=11 November 2020}}</ref> An additional £210 million was awarded to Rolls-Royce by the British government in 2021, complemented by a £195 million contribution from private firms.<ref>{{cite web |title=Rolls-Royce gets funding to develop mini nuclear reactors |url=https://www.bbc.co.uk/news/business-59212983 |date=9 November 2021 |publisher=BBC |access-date=10 November 2021}}</ref> In November 2022, Rolls-Royce announced that the sites at Trawsfynydd, Wylfa, Sellafield and Oldbury would be prioritised for assessment as potential locations for multiple SMRs.<ref>{{cite web |title=Study identifies potential Rolls-Royce SMR sites |url=https://www.world-nuclear-news.org/Articles/Study-identifies-potential-Rolls-Royce-SMR-sites |date=11 November 2022 |publisher=World Nuclear News |access-date=16 November 2022}}</ref>

The British government launched Great British Nuclear in July 2023 to administer a competition to create SMRs, and will co-fund any viable project.<ref name=BBCJul23>{{cite news |url=https://www.bbc.co.uk/news/business-59212992 |archive-url=https://web.archive.org/web/20230610030544/https://www.bbc.com/news/business-59212992 |title=Nuclear energy: How environmentally-friendly and safe is it? |date=17 July 2023 |work=BBC News |access-date=19 July 2023 |archive-date=10 June 2023}}</ref>

=== United States === Researchers at Oregon State University (OSU), headed by José N. Reyes Jr., designed a prototype SMR in 2007.<ref>{{cite web |last1=Learn |first1=Scott |title=Oregon State professor wants to help power a nuclear renaissance |url=https://www.oregonlive.com/environment/2010/03/oregon_state_professor_wants_t.html |website=oregonlive.com/ |date=7 March 2010 |publisher=The Oregonian |access-date=31 May 2025}}</ref> Their research and design component prototypes formed the basis for NuScale Power's commercial SMR design. NuScale and OSU developed the first full-scale SMR prototype in 2013<ref>{{cite web |title=The NuScale Design |url=https://www.nrc.gov/docs/ML1616/ML16161A723.pdf |website=www.nrc.gov |publisher=NRC |access-date=24 August 2025}}</ref> and NuScale received the first Nuclear Regulatory Commission Design Certification approval for a commercial SMR in the United States in 2022.<ref>{{cite news |last=Musto |first=Julia |title=US approves first small modular nuclear reactor design |url=https://www.foxnews.com/tech/u-s-approves-first-small-modular-nuclear-reactor-design |date=25 January 2023 |work=FOX News |access-date=17 December 2023}}</ref> In 2025, two more NuScale SMRs, the VOYGR-4 and VOYGR-6, received NRC approval.<ref>{{cite web |title=NRC Approves NuScale Power's Uprated Small Modular Reactor Design |url=https://www.energy.gov/ne/articles/nrc-approves-nuscale-powers-uprated-small-modular-reactor-design#:~:text=Modular%20Reactor%20Design-,NRC%20Approves%20NuScale%20Power's%20Uprated%20Small%20Modular%20Reactor%20Design,SMR%20design%20approved%20by%20NRC.&text=The%20U.S.%20Nuclear%20Regulatory%20Commission,for%20the%20U.S.%20nuclear%20sector.&text=NuScale%20Power%20submitted%20its%20standard,power%2C%20or%20even%20operator%20action. |website=energy.gov/ | date=30 May 2025 |publisher=NRC |access-date=27 August 2025}}</ref> The US Department of Energy had estimated the first SMR in the United States would be completed by NuScale Power around 2030,<ref>{{cite web |title=Technology Deployment |url=https://www.iea.org/energy-system/electricity/nuclear-power#tracking |access-date=19 December 2023 |website=iea.org |publisher=US Department of Energy}}</ref> but this deal has since fallen through after the customers backed out due to rising costs.<ref name=science-20231110 /><ref name="CNBC" /> In 2024, the US had nearly 4 gigawatts in announced SMR projects in addition to almost 3 GW in early development or pre-development stages, according to Utility Dive.<ref name="UD-SMR">{{cite web |url=https://www.utilitydive.com/news/small-modular-reactor-haleu-ge-hitachi-nuscale/709978/ |title=Global small modular reactor pipeline hits 22 GW, with US leading the market: WoodMac |last=Martucci |first=Brian |website=Utility Dive |date=12 March 2024 |access-date=4 December 2025}}</ref>

SMRs differ in terms of staffing, safety and deployment time.<ref>{{cite web |date=2015 |title=Licensing Small Modular Reactors: An Overview of Regulatory and Policy Issues |url=https://www.hoover.org/sites/default/files/research/docs/ostendorff_licensingsmrs_2rs_reduced_4_0.pdf |website=Hoover Institution}}</ref> US government studies to evaluate SMR-associated risks are claimed to have slowed the licensing process.<ref name="smallBeauty" /><ref name="sciencedirect.com" /> One main concern with SMRs and their large number, needed to reach an economic profitability, is preventing nuclear proliferation.<ref name="areva-20100618" /><ref name="auto1b" />

{{wide image|Former Genoa coal power plant.jpg|400px|Former Genoa coal power plant and dry cask storage, July 2023. The La Crosse BWR is not in these photos since it was demolished in 2019.||right |alt=Former Genoa coal power plant and dry cask storage, July 2023. The La Crosse BWR is not in these photos since it was demolished in 2019.}} NuScale Power is working with Wisconsin's Dairyland Power to evaluate VOYGR SMR power plants for potential deployment. The US leader in SMR technology believes its load-following capabilities can be used to support Dairyland's existing renewables portfolio, as well as facilitate growth. Additionally, VOYGR plants are well-suited for replacing Dairyland's retiring coal plant sites, preserving critical jobs and helping communities transition to a decarbonized energy system.<ref>{{cite web |title=Dairyland Power Cooperative WisconsinDairyland Power Cooperative Wisconsin |url=https://www.nuscalepower.com/en/projects |website=nuscalepower.com |publisher=NuScale Power |access-date=16 December 2023}}</ref>

The Tennessee Valley Authority was authorized to receive an Early Site Permit (ESP) by the Nuclear Regulatory Commission for siting an SMR at its Clinch River Nuclear Site in Tennessee in December 2019.<ref>{{Cite web |url=https://www.nrc.gov/reading-rm/doc-collections/news/2019/19-064.pdf |title=NRC to Issue Early Site Permit to Tennessee Valley Authority for Clinch River Site |last=U.S. Nuclear Regulatory Commission |date=17 December 2019 |website=nrc.gov |access-date=24 December 2019}}</ref> This ESP is valid for 20 years, and addresses site safety, environmental protection and emergency preparedness. This ESP is applicable for any light-water reactor SMR design under development in the United States.<ref>{{Cite web |url=https://www.tva.gov/Energy/Technology-Innovation/Small-Modular-Reactors |title=TVA - Small Modular Reactors |website=www.tva.gov |access-date=8 April 2016}}</ref> In 2025, the TVA contracted Entra1 Energy to manage the building of a 6-Gigawatt NuScale Power SMR plant on TVA's site.<ref>{{cite web |title=NuScale Proudly Supports TVA and ENTRA1 Energy Announcement of Landmark 6-Gigawatt Small Module Reactor (SMR) Deployment Program |url=https://www.nuscalepower.com/press-releases/2025/nuscale-proudly-supports-tva-and-entra1-energy-announcement-of-landmark-6-gigawatt-small-module-reactor-smr-deployment-program |website=nuscalepower.com |publisher=NuScale Power |access-date=5 January 2026}}</ref>

NuScale Power is working with Associated Electric Cooperative Inc. (Associated) in Missouri to evaluate deployment of VOYGR SMR power plants as part of Associated's due diligence to explore reliable, responsible sources of energy.<ref>{{cite web |title=Associated Electric Cooperative Missouri |url=https://www.nuscalepower.com/en/projects |website=nuscalepower.com |publisher=NuSclae Power |access-date=16 December 2023}}</ref> Their design of SMRs are intended to operate uninterrupted, with LEU refueling required every 2 years. Some of their SMR modules can be moved into a separate refueling pool while the remaining modules remain active.<ref>{{cite web |title=Refueling Operations Report for the NuScale Power Module |url=https://www.nrc.gov/docs/ML0908/ML090850080.pdf |website=nrc.gov |publisher=NuScale Power| date=2009 |access-date=5 April 2026}}</ref>

The Utah Associated Municipal Power Systems (UAMPS) had partnered with Energy Northwest to explore siting a NuScale Power reactor in Idaho, possibly on the Department of Energy's Idaho National Laboratory.<ref>{{Cite web |url=http://www.uamps.com/index.php/38-items/24-carbon-free-power-project |title=Carbon Free |website=www.uamps.com |access-date=8 April 2016 |archive-date=19 January 2017 |archive-url=https://web.archive.org/web/20170119125359/http://www.uamps.com/index.php/38-items/24-carbon-free-power-project }}</ref><ref name=eenews-20231109>{{cite news |url=https://www.eenews.net/articles/nuscale-cancels-first-of-a-kind-nuclear-project-as-costs-surge/ |title=NuScale cancels first-of-a-kind nuclear project as costs surge |last=Bright |first=Zach |website=E&E News |publisher=Politico |date=9 November 2023 |access-date=9 November 2023}}</ref> Known as the Carbon Free Power Project, the project was canceled in November 2023 for cost reasons.<ref name=eenews-20231109 /> NuScale said in January 2023 the target price for power from the plant was $89 per megawatt hour, up 53% from the previous estimate of $58 per MWh, raising concerns about customers' willingness to pay.<ref>{{cite web |last1=Gardner |first1=Timothy |title=My View Following Saved Energy Energy Grid & Infrastructure Nuclear Sustainable Markets NuScale ends Idaho project, in blow to US nuclear power ambitions |url=https://www.reuters.com/business/energy/nuscale-power-uamps-agree-terminate-nuclear-project-2023-11-08/ |website=reuters.com |date=9 November 2023 |publisher=Reuters |access-date=15 December 2023}}</ref>

The Galena Nuclear Power Plant in Galena, Alaska, was a proposed micro nuclear reactor installation. It was a potential deployment for the Toshiba 4S reactor.<ref>{{Cite web |title=Nuclear Power and the Perils of Pioneering |url=https://www.uaf.edu/acep-blog/nuclear-power-and-the-perils-of-pioneering.php |access-date=5 December 2023 |website=www.uaf.edu |language=en}}</ref> The project was "effectively stalled". Toshiba never began the expensive process for approval that is required by the US Nuclear Regulatory Commission.

In October 2024, Google agreed to commission multiple small modular reactors from Kairos Power to power its artificial intelligence processing, with the first to be operational in 2030.<ref name="DeGeurin 2024">{{cite web |last=DeGeurin |first=Mack |title=Google bets big on 'mini' nuclear reactors to feed its AI demands |website=Popular Science |date=15 October 2024 |url=https://www.popsci.com/environment/google-mini-nuclear-reactors-ai/ |access-date=15 October 2024}}</ref><ref name="Silva 2024">{{cite web |last=Silva |first=João da |title=Google turns to nuclear to power AI data centres |website=BBC |date=15 October 2024 |url=https://www.bbc.com/news/articles/c748gn94k95o |access-date=15 October 2024}}</ref><ref name="Terrell 2024">{{cite web |last=Terrell |first=Michael |title=New nuclear clean energy agreement with Kairos Power |website=Google |date=14 October 2024 |url=https://blog.google/outreach-initiatives/sustainability/google-kairos-power-nuclear-energy-agreement/ |access-date=15 October 2024}}</ref>

In December 2025, the Department of Energy selected Tennessee Valley Authority and Holtec to receive grants of $400 million each to support early deployment of advanced light-water SMRs, with an SMR defined as having output of between 50 and 350 MWe.<ref name=wnn-20251203>{{cite news |url=https://www.world-nuclear-news.org/ |title=Two SMR projects selected for US federal funding |website=World Nuclear News |date=3 December 2025 |access-date=4 December 2025}}</ref>

== Notes == {{Notelist}}

== References == <references>

<ref name=":0b">{{cite web |url=https://www.oecd-nea.org/ndd/pubs/2016/7213-smrs.pdf |title=Small Modular Reactors: Nuclear Energy Market Potential for Near-term Deployment |date=2016 |website=OECD-NEA.org}}</ref>

<ref name=":1">{{cite web |url=https://www.sustainability-times.com/uncategorized/squaring-the-energy-circle-with-smrs/ |title=Squaring the energy circle with SMRs |last=Furfari |first=Samuele |date=31 October 2019 |website=Sustainability Times |language=en-GB |access-date=16 April 2020}}</ref>

<ref name="WNASMRs">{{cite web |author= |date=2026-03-24 |title=Small Modular Reactors |website=World Nuclear Association |url=https://world-nuclear.org/information-library/nuclear-power-reactors/small-modular-reactors/small-modular-reactors |access-date=2026-03-27}}</ref>

<ref name="SustainabilityTimes_2019-11-29">{{cite web |last=Berniolles |first=Jean-Marie |date=29 November 2019 |title=De-mystifying small modular reactors |url=https://www.sustainability-times.com/low-carbon-energy/de-mystifying-small-modular-reactors/ |website=Sustainability Times |language=en-GB |access-date=16 April 2020}}</ref>

<ref name="auto1b">{{cite web |last=Trakimavičius |first=Lukas |date=Nov 2020 |title=Is Small Really Beautiful? The Future Role of Small Modular Nuclear Reactors (SMRs) In The Military |url=https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf |website=NATO Energy Security Centre of Excellence |language=en |access-date=5 December 2020 |archive-date=31 July 2022 |archive-url=https://web.archive.org/web/20220731034722/https://www.enseccoe.org/data/public/uploads/2020/11/02.-solo-article-lukas-smr-eh-15-web-version-final.pdf }}</ref>

<ref name="auto22">[http://www.roe.com/pdfs/technical/Galena/Overview%20Whitepaper%20Rev02.pdf "The Galena Project Technical Publications"], p. 22, [http://www.roe.com ''Burns & Roe'']</ref>

<ref name="nei-20230118">{{cite news |url=https://www.neimagazine.com/advanced-reactorsfusion/iaea-ups-support-for-smrs-10528638/ |title=IAEA ups support for SMRs |last=Perera |first=Judith |publisher=Nuclear Engineering International |date=18 January 2023 |access-date=24 January 2023}}</ref>

<ref name="smallBeauty">{{cite web |last=Lyman |first=Edwin |date=September 2013 |title=Small Isn't Always Beautiful: Safety, Security, and Cost Concerns about Small Modular Reactors |website=Union of Concerned Scientists |url=https://www.ucs.org/sites/default/files/2019-10/small-isnt-always-beautiful.pdf |archive-url=https://web.archive.org/web/20250316022157/https://www.ucs.org/sites/default/files/2019-10/small-isnt-always-beautiful.pdf |archive-date=2025-03-16 |access-date=2026-04-26}}</ref>

<ref name="UCS1">{{cite web |title=Small Modular Reactors: Safety, Security and Cost Concerns (2013) |url=https://www.ucsusa.org/nuclear-power/nuclear-power-technology/small-modular-reactors |website=Union of Concerned Scientists |language=en |access-date=2 April 2019}}</ref>

</references>

== Further reading == {{Refbegin}} * {{cite book |editor=Daniel T. Ingersoll and Mario D. Carelli |title=Handbook of Small Modular Nuclear Reactors |publisher=Elsevier – Woodhead Publishing |date=2020 |isbn=978-0-12-823916-2 |doi=10.1016/c2019-0-00070-2 |edition=2nd}} * {{cite web |author=Office of Nuclear Energy, Science and Technology |title=DOE Fundamentals Handbook: Nuclear Physics and Reactor Theory |volume=2 |date=January 1993 |publisher=U.S. Department of Energy |url=http://www.hss.doe.gov/nuclearsafety/techstds/docs/handbook/h1019v2.pdf |id=DOE-HDBK-1019, DE93012223 |ref={{harvid|DOE-HDBK-1019|1993}} |archive-url=https://web.archive.org/web/20121109194948/http://www.hss.doe.gov/nuclearsafety/techstds/docs/handbook/h1019v2.pdf |archive-date=9 November 2012}} * {{cite journal |last1=Vinoya |first1=Carlo L. |last2=Ubando |first2=Aristotle T. |last3=Culaba |first3=Alvin B. |last4=Chen |first4=Wei-Hsin |title=State-of-the-Art Review of Small Modular Reactors |journal=Energies |volume=16 |issue=7 |date=3 April 2023 |issn=1996-1073 |doi=10.3390/en16073224 |doi-access=free |page=3224}} {{Refend}}

== External links == {{Commons category|Small modular reactors}} * {{cite web |title=Advanced Reactor Information System (ARIS) IAEA database |website=ARIS–IAEA |date=17 May 2016 |url=https://aris.iaea.org/ |access-date=15 December 2023}} * {{cite web |title=Small Nuclear Power Reactors |website=World Nuclear Association |date=7 February 2018 |url=https://www.world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/small-nuclear-power-reactors.aspx |ref={{sfnref | World Nuclear Association | 2018}} |access-date=5 December 2023}} * {{cite web |title=Small Modular Reactors: Challenges and Opportunities |website=Nuclear Energy Agency (NEA) |date=3 July 2023 |url=https://www.oecd-nea.org/jcms/pl_57979/small-modular-reactors-challenges-and-opportunities |ref={{sfnref | Nuclear Energy Agency (NEA) | 2023}} |access-date=7 December 2023}} * {{cite web |title=Small Modular Reactors (SMR) |website=BASE |url=https://www.base.bund.de/EN/ns/ni-germany/smr/small-modular-reactors_node.html |ref={{sfnref | BASE}} |access-date=9 December 2023}} * [https://web.archive.org/web/20100624035928/http://www.ne.doe.gov/ DOE Office of Nuclear Energy] * [https://www.nrc.gov American Nuclear Regulatory Commission] * [https://www.world-nuclear.org World Nuclear Association] * [https://www.ans.org American Nuclear Society] * [https://www.iaea.org International Atomic Energy Agency] * [https://www.iaea.org/INPRO/3rd_Dialogue_Forum/07.Ingersoll.pdf Overview and Status of SMRs Being Developed in the United States] {{Webarchive|url=https://web.archive.org/web/20140328192935/http://www.iaea.org/INPRO/3rd_Dialogue_Forum/07.Ingersoll.pdf |date=28 March 2014 }}

Category:Nuclear power reactor types Category:Small modular reactor