Table of Contents
1. Introduction to Small Modular Reactors
Small Modular Reactors (SMRs) are a class of advanced nuclear fission reactors with a capacity up to about 300 MWe per unit – roughly one-third or less the output of a typical modern nuclear plant. They operate on the same fundamental principle as conventional reactors (splitting atomic nuclei to produce heat, which generates steam to drive turbines and produce electricity).
Key Characteristics
- Small in physical size and power output
- Modular design with factory-fabricated components
- Components transported to site for assembly
- Capacity typically up to 300 MWe per unit
Conventional Reactors
- Large physical size and power output (1000+ MWe)
- Custom-built on-site with sprawling structures
- Construction can take a decade or more
- Requires large cooling towers and complex infrastructure
Key Differences
Size and Footprint
An SMR may occupy only a fraction of the area of a large plant – some designs tout a footprint of only a few acres. Multiple SMR units can be clustered to scale up output if needed, but even a single unit can be deployed to serve smaller grids or remote regions where a giant reactor wouldn't be feasible.
Factory Construction
Unlike traditional reactors built mostly on-site, SMR components can be mass-produced in factories. This factory fabrication allows for standardization and learning-curve benefits (akin to assembly-line production) which can potentially lower costs and construction times over successive builds. By shipping modular sections by truck, rail, or barge, on-site construction is faster and less complex.
Passive Safety
SMRs often incorporate advanced safety features that make them less reliant on active controls or external power for emergency cooling. Many designs are intended to be installed underground or underwater, adding an extra barrier against external events.
Economic Scale
Large nuclear plants benefit from economies of scale (a single 1000 MWe reactor can produce power relatively cheaply once running), whereas a single SMR produces less power. The SMR concept instead pursues economies of series – building many standardized units to drive down per-unit costs.
"Unlike conventional nuclear reactors that are built on site, SMRs are smaller, can be made in factories, and could transform how power stations are built by making construction faster and less expensive."
— UK Government Official
2. Key Technological Advances
Passive and Inherent Safety
A major innovation in many SMR designs is the use of passive safety systems. Traditional reactors rely on engineered active systems (pumps, diesel generators, operator actions) to respond to accidents.
- Self-cooling without human intervention
- Natural convection cooling systems
- Smaller cores with less residual heat
- "Walk-away safe" design philosophy
Modular, Factory-Built Systems
The "M" in SMR, modularity, is not just about physical size but about how the plants are constructed. SMR designs take advantage of factory fabrication for major components or entire reactor modules.
- Factory quality control and parallel production
- Incremental deployment capability
- Standardization across multiple units
- Shorter project timelines (2-3 years vs. 5-10)
Advanced Cooling and Reactor Types
Light-water Reactors (LWRs)
Small pressurized or boiling water reactors that use ordinary water for cooling and moderation. Examples: NuScale, Rolls-Royce SMR, GE Hitachi's BWRX-300.
High-temperature Gas-cooled Reactors
Use gas (often helium) as coolant and graphite as moderator. Run at much higher temperatures (750°C+). Examples: China's HTR-PM, X-energy's Xe-100.
Molten Salt Reactors (MSRs)
Use molten fluoride salt as coolant or fuel medium. Run at low pressure and high temperature. Examples: Terrestrial Energy IMSR, Kairos Power's FHR.
Fast Neutron Reactors
Forego moderator and use fast fission, usually cooled by liquid metal. Examples: Russia's BREST-OD-300, TerraPower Natrium, ARC-100.
Advanced Fuels
TRISO Fuel
TRISO (Tri-structural Isotropic) fuel particles are often called "poppy-seed sized" microspheres – each particle has a tiny kernel of uranium fuel surrounded by three concentric layers of carbon and ceramic.
- Cannot melt in a reactor
- Withstands extreme temperatures (up to ~1600°C)
- Each particle acts as its own containment
- Used in high-temperature gas reactors
HALEU Fuel
HALEU (High-Assay Low-Enriched Uranium) is uranium fuel enriched to between 5% and 20% U-235, compared to less than 5% in conventional reactors.
- Enables smaller reactor designs
- Longer operating cycles (up to 20-30 years)
- Increased efficiency and better fuel utilization
- Required for most advanced reactor designs
"SMRs leverage a suite of advanced technologies: passive safety design, modular construction methods, diverse cooling strategies, and new fuel forms that improve safety and performance. These innovations collectively aim to make nuclear energy safer, more flexible, and more affordable."
3. Global Deployment Status
Global SMR Deployment Status
Operational, Under Construction, and Planned
As of 2025, only a few SMRs have been deployed in practice, but many projects are in the pipeline worldwide. The IAEA reports that four SMRs are in advanced stages of construction (in Argentina, China, and Russia) and that the first operational units are expected around 2030 for many countries' programs.
Global SMR Projects Map (2025)
Operational SMRs
Russia's Akademik Lomonosov
World's first commercial SMR deployment (2019). Two 35 MWe PWR reactors mounted on a barge, supplying ~70 MWe to the remote Arctic town of Pevek.
China's HTR-PM
High-temperature gas-cooled pebble-bed SMR at Shidao Bay. Two reactor modules driving one 210 MWe turbine. Connected to grid in December 2021.
SMRs Under Construction
Argentina's CAREM-25
25 MWe integral pressurized water reactor near Buenos Aires. Civil works ~85% complete, targeting startup by 2028.
China's ACP100 "Linglong One"
125 MWe multi-purpose SMR at Changjiang, Hainan Island. Construction began July 2021, completion expected around 2026.
Russia's BREST-OD-300
300 MWe lead-cooled fast reactor in Seversk. Construction started June 2021, part of Russia's Generation IV reactor strategy.
Licensed or Ready to Build
NuScale (USA)
First SMR to be certified by the U.S. Nuclear Regulatory Commission (January 2023). 50 MWe module design, with first unit expected by late 2020s.
GE Hitachi BWRX-300 (Canada)
Advanced stages of review by Canadian regulator CNSC. Site preparation license granted for Darlington site in Ontario.
Rolls-Royce SMR (UK)
470 MWe design undergoing Generic Design Assessment by UK regulators. Short-listed for government support with hopes for first unit in early 2030s.
Planned and Proposed SMRs
Dozens of SMR projects are in planning stages globally. Countries that have never had nuclear power are considering SMRs as an entry, and countries with established nuclear fleets are looking to SMRs to complement larger plants.
In summary, Russia and China have been first movers in actually building SMRs (leveraging state-backed programs), while Argentina is close behind with its small PWR. North America, Europe, and others are laying the groundwork for the late 2020s and 2030s. The first grid-connected SMRs in the West are expected in Canada and the U.S. before 2030, with multiple units quickly following if all goes well. By one industry survey, as many as 300 SMRs could be online globally by 2050 in a high-adoption scenario, supplying reliable clean power in support of climate goals.
4. National & Company Initiatives
Many countries see SMRs as a strategic addition to their energy mix or an export opportunity. Below we highlight initiatives in several nations and by various companies, including project names, status, size, and goals.
Russia
Akademik Lomonosov
World's first commercial SMR deployment (2019). Two 35 MWe KLT-40S reactors on a floating barge.
RITM-200N
50 MWe land-based SMR planned for Yakutia, with target operation date of 2028.
BREST-OD-300
300 MWe lead-cooled fast neutron SMR under construction in Seversk as part of "Proryv" program.
Strategic Goals
- • Power remote Arctic and far-east areas
- • Export SMR technology globally
- • Maintain global leadership in nuclear technology
- • Deploy multiple small units where large plants aren't feasible
China
HTR-PM
High-Temperature gas-cooled Reactor Pebble-bed Module. Two 250 MWt reactors driving one 210 MWe turbine. Operational since 2023.
ACP100 "Linglong One"
125 MWe pressurized water SMR under construction in Hainan. Expected completion around 2026.
TMSR-LF1
2 MW thermal thorium molten salt experimental reactor completed in 2021. Plans for a larger 373 MWt version by 2030.
Strategic Goals
- • Complement large nuclear build-out
- • Export SMRs along Belt and Road Initiative
- • Provide power to regions not served by large reactors
- • Develop high-temperature reactors for industrial heat and hydrogen
United States
NuScale Power
77 MWe light-water reactor module, first SMR to receive NRC certification (2023). VOYGR plant can have up to 12 modules (924 MWe).
TerraPower Natrium
345 MWe sodium-cooled fast reactor with integrated molten salt heat storage. Site selected at retiring coal plant in Wyoming.
X-energy Xe-100
Pebble-bed high-temperature gas reactor. Four 80 MWe modules (320 MWe total) to be built at Dow chemical facility in Texas.
Strategic Goals
- • Rejuvenate U.S. nuclear sector
- • Provide flexible clean power for the grid
- • Replace retiring coal plants
- • Compete globally with Russian and Chinese offerings
Canada
GE Hitachi BWRX-300
300 MWe SMR at Darlington Nuclear site in Ontario. Site preparation underway, operational by 2028.
ARC-100
100 MWe sodium-cooled fast SMR planned for Point Lepreau site in New Brunswick. Target: around 2030.
Global First Power MMR
5 MWe "Micro Modular Reactor" at Chalk River Laboratories. Aims for first power by 2026.
Strategic Goals
- • Decarbonize electricity and heavy industry
- • Provide power to remote northern communities
- • Replace retiring coal plants
- • Create an exportable SMR industry
United Kingdom
Rolls-Royce SMR
470 MWe pressurized water reactor. Undergoing regulatory assessment, targeting first unit in early 2030s.
Great British Nuclear (GBN)
Government body evaluating multiple SMR designs including EDF Nuward, GE Hitachi BWRX-300, Holtec SMR-160, NuScale, and Westinghouse.
Strategic Goals
- • Rejuvenate nuclear power (25% of electricity by 2050)
- • Enhance energy security
- • Meet net-zero targets
- • Develop exportable UK-led reactor technology
Poland
Orlen Synthos Green Energy
Joint venture selected GE Hitachi's BWRX-300 design with seven potential sites. First unit targeted by 2028-2029.
Ambitious Deployment
Plans for up to 10 BWRX-300 reactors by early 2030s, each 300 MWe, for a total of ~3 GWe.
Strategic Goals
- • Transition away from coal
- • Enhance energy security
- • Meet European climate goals
- • Reduce dependence on imported fuels
South Korea
SMART Reactor
100 MWe (330 MWt) pressurized water reactor. First SMR to receive standard design approval (2012). Updated SMART100 approved in 2023.
Saudi Arabia Partnership
Agreement to collaborate on commercializing SMART, including building a first unit in Saudi Arabia.
Strategic Goals
- • Export SMR technology to Middle East and Asia
- • Ensure Korea's nuclear industry has competitive products
- • Decarbonize Korea's industrial sector
- • Develop SMRs for remote islands and industrial complexes
Other Countries and Initiatives
🇫🇷 France
Developing Nuward (~170 MWe PWR) with prototype targeted by 2030.
🇯🇵 Japan
Investing in 50 MWe water-cooled SMR by late 2020s. Operates HTTR test reactor.
🇮🇩 Indonesia
Signed deals with multiple vendors to deploy SMRs to islands by 2030s.
🇷🇴 Romania
Partnered with U.S. to deploy NuScale 6-module plant by around 2030.
🇦🇪 UAE
Exploring SMRs for desalination and industrial process heat.
🇦🇷 Argentina
CAREM-25 prototype under construction, Latin America's first SMR.
Overall, the global landscape shows at least 18 countries with concrete SMR plans – either via domestic development or import. Each has different motivations (for some, it's replacing coal or diesel in climate goals; for others, it's energy independence or industrial heat). The next 5–10 years will be critical in determining which SMR designs actually get built and how quickly countries move from MOUs to pouring concrete.
5. Applications & Use Cases
Applications of SMRs
Beyond electricity: The versatile roles of Small Modular Reactors
One of the advantages of SMRs is their flexibility in deployment and applications. Because of their smaller size, enhanced safety, and often higher temperature output, SMRs can serve in roles beyond what large nuclear plants typically do.
Grid Electricity Generation
This is the main focus of most SMRs – providing baseload or load-following power to electrical grids. SMRs can be connected to a grid either as a single unit or as a multi-module plant, depending on the needed capacity.
Key Advantages
- Incremental capacity additions to match demand growth
- Right-sized for smaller or weaker grids
- Load-following capability to complement renewables
- Potential to replace retiring coal plants
SMR power plant connected to grid
Remote and Off-Grid Power
A transformative application of very small reactors (vSMRs or microreactors) is providing energy to remote locations that currently rely on diesel generators or have no reliable power.
Key Applications
- Arctic or island communities
- Mining operations in remote areas
- Military bases and research stations
- Disaster relief and humanitarian missions
Microreactor for remote community
Desalination (Water Production)
SMRs are very well-suited to cogenerate fresh water through desalination. Nuclear reactors have long been considered for desalination because they produce heat (and power) that can drive desalination processes.
Key Benefits
- Simultaneous production of electricity and fresh water
- Reduced fossil fuel use for desalination
- Ideal for water-stressed coastal regions
- Floating SMRs can be stationed off arid coastal regions
SMR-powered desalination plant
Industrial Process Heat
Many industries require large amounts of heat (in the form of steam or high-temperature air/gas). SMRs, especially advanced designs that reach higher temperatures, can supply carbon-free process heat for industries.
Key Applications
- Chemical production processes
- Oil sands extraction and refining
- Steelmaking and cement production
- District heating for cities
SMR providing heat to industrial facility
Hydrogen and Synthetic Fuel Production
With the push for green hydrogen (hydrogen made without fossil fuels), SMRs present an attractive production method. Electrolyzers need electricity – SMRs can provide continuous, carbon-free power for electrolysis of water to produce hydrogen gas.
Production Methods
- Electrolysis powered by SMR electricity
- Thermochemical cycles using high-temperature heat
- High-temperature steam electrolysis (more efficient)
- Synthetic fuel production (H₂ + captured CO₂)
SMR-powered hydrogen production facility
Key Advantages
- 24/7 operation for maximum electrolyzer utilization
- Complementary to renewable hydrogen production
Over the longer term (post-2035), if countries are serious about e-fuels (electrofuels) for aviation/marine or large-scale hydrogen for steel and fertilizer, nuclear SMRs can provide a reliable source of clean hydrogen alongside solar and wind. One analysis suggests a single 600 MWt high-temperature SMR could produce on the order of 50,000 tonnes of H₂ per year via high-temp electrolysis.
Comparative Data: Costs, Timelines, and Technologies
Levelized Cost of Electricity
- • Light-water SMR: ~$90 per MWh
- • Gas-cooled SMR: ~$82 per MWh
- • Molten-salt SMR: ~$80 per MWh
- • Target (NuScale): $58 per MWh by 2030
- • Rolls-Royce SMR: $70-80 per MWh in series
Deployment Timelines
- • Russia/China: Already operational (2019-2021)
- • Argentina: Late 2020s (CAREM-25)
- • Canada: 2026-2028 (MMR, BWRX-300)
- • United States: ~2028 (X-energy, TerraPower)
- • UK/France/Japan: Early/mid-2030s
Technology Comparison
- • LWR SMRs: Proven tech, easier licensing
- • HTGRs: Higher temps, industrial heat
- • MSRs: Low pressure, high efficiency
- • Fast SMRs: Fuel efficiency, waste reduction
- • Microreactors: Remote deployment, simplicity
6. Barriers to Adoption
Challenges that must be overcome for widespread deployment
Despite their promise, SMRs face several barriers and challenges that need to be addressed for widespread adoption. Understanding these obstacles is crucial for policymakers, industry leaders, and investors.
Regulatory and Licensing Challenges
Nuclear regulation is understandably rigorous, and most regulations were written with large reactors in mind. Certifying a novel SMR design can be time-consuming and costly.
Key Issues
- High fixed costs of licensing spread over fewer MWh
- Regulatory staff capability gaps for new technologies
- Lengthy review timelines for first-of-a-kind designs
- Multi-module licensing complexity
Progress Being Made
- U.S. NRC developing new rule for advanced reactors
- Canada exploring joint reviews with other countries
- IAEA encouraging harmonization of SMR standards
Financing and Economics
Building the first few SMRs will be expensive on a per-kW basis. While the modular approach should eventually lower costs, early units won't have volume discounts.
Key Challenges
- Investor hesitancy due to history of nuclear cost overruns
- "Chicken and egg" issue with economies of series
- Uncertainty about who bears first-of-a-kind cost overruns
- Limited supply chain for specialized components
Potential Solutions
- Government incentives (production tax credits, funding)
- Innovative financing models (fleet-based, public-private)
- Regulated asset base models for first SMRs
Fuel Supply Chain
Several SMRs need HALEU fuel (enriched >5% U-235). Right now, the world's capacity to produce HALEU is very limited, creating a potential bottleneck.
Key Issues
- Limited HALEU enrichment capacity globally
- Few facilities capable of TRISO fuel fabrication
- Geopolitical tensions affecting fuel supply
- Transport and licensing challenges for HALEU
Initiatives Underway
- U.S. DOE HALEU Availability Program
- X-energy building TRISO fuel plant in Washington state
- Down-blending of high-enriched uranium for interim supply
Public Acceptance and Policy Support
Public perception of nuclear power can be a barrier, especially when introducing a lot of small reactors instead of one big plant. Some members of the public might be concerned that having multiple SMR sites increases the number of "nuclear locations".
Key Concerns
- Fear of accidents or nuclear stigma
- Concerns about nuclear waste management
- Perception of "untested" technology
- Outdated regulations that don't permit smaller reactors
Addressing These Issues
- Transparent community engagement and education
- Emphasizing climate and economic benefits
- Clear waste management plans
- Updating laws to accommodate SMRs
Waste and Decommissioning
While not as immediate a barrier, the long-term handling of many small reactor units needs planning. If an SMR has a core vessel that is sealed for life, what happens at end of life?
Key Considerations
- "Return to sender" approach for sealed modules
- Decommissioning funds for each SMR site
- Long-term waste storage solutions
On the positive side, the decommissioning of an SMR is easier in many cases (smaller radioactive inventory, possibly factory-refurbished). Still, demonstrating efficient decommissioning will be important for public and regulatory confidence.
Potential Advantages
- Smaller radioactive inventory per unit
- Potential for factory refurbishment
- Some advanced SMRs can consume existing waste
In summary, SMRs face hurdles in regulation, financing, fuel supply, public acceptance, and infrastructure. None of these is insurmountable – indeed several are being actively addressed via international collaboration and government initiatives. But these barriers mean that SMRs, despite hype, will ramp up more slowly than their proponents might wish. Early 2020s are about resolving these issues: crafting new rules, proving costs, building fuel facilities, and gaining community buy-in. The sector's success depends on effectively overcoming these challenges in the next decade.
Forecasts and Outlook for SMRs
The future landscape of small modular reactors
7. Future Outlook
The outlook for SMRs is cautiously optimistic, with numerous projections suggesting they will become a significant part of the energy landscape by mid-century, especially as the world strives for net-zero emissions.
Market Size and Growth Projections
Various market research reports have sized the SMR market in the coming decades. One estimate suggests that by 2030, the global SMR market could be on the order of $70 billion, growing rapidly thereafter as deployments accelerate.
Key Projections
- OECD NEA: Potential for 380 GW by 2040
- IEA Net Zero: Over 1,000 SMRs by 2050
- NEI: 300 SMRs (90 GW) in U.S. by 2050
- By 2030: 20-30 SMR units operating globally
Projected SMR growth chart
Role in Net-Zero Emissions Goals
SMRs are often cited as a crucial tool for achieving net-zero carbon emissions by 2050. The logic is that certain sectors and loads cannot be fully served by intermittent renewables alone – and SMRs provide firm, dispatchable clean power and heat to fill that gap.
Key Contributions
- Reliable low-carbon power when renewables unavailable
- Decarbonization of heat and transport via hydrogen
- Clean energy for regions with limited renewables
- Lower system costs for achieving decarbonization
SMRs in net-zero energy mix
Complementing Renewables
As grids get dominated by wind and solar, maintaining stability and meeting peak demand on calm nights becomes a challenge. SMRs, especially load-following ones or those with integrated storage, can ramp up output when renewables dip.
Key Synergies
- Filling gaps when renewables are unavailable
- Distributed deployment closer to loads
- Hybrid energy systems with integrated storage
- Replacing retiring coal plants one-for-one
SMR-renewable hybrid system
Deployment Timeline by Region
2020
Russia & China
First SMRs
2025-2028
Canada & Argentina
First Western SMRs
2030
UK & US
First Commercial Fleet
2035-2040
Global Expansion
Multiple Vendors
2050
Mature Industry
Global Deployment
Challenges to Overcome
Economic Viability
Despite promising projections, SMRs still need to demonstrate economic competitiveness. First-of-a-kind costs remain high, and the learning rate for cost reduction is uncertain. Policy support and carbon pricing may be needed to bridge the gap.
Regulatory Frameworks
Many countries lack regulatory frameworks adapted to SMR characteristics. Harmonization of standards across borders would accelerate deployment but remains challenging due to national sovereignty concerns.
Public Acceptance
Public perception of nuclear energy varies widely. SMRs need to overcome historical concerns about safety, waste, and proliferation through transparent communication and community engagement.
Supply Chain Development
Building robust supply chains for SMR components and fuel will take time. The nuclear-grade manufacturing capacity has atrophied in many countries and needs revitalization.
8. Conclusion
The trajectory for SMRs is very promising but hinges on the next decade of demonstration and deployment. If early projects meet expectations, SMRs could usher in a new era where nuclear power is more accessible, flexible, and integrated than ever before – truly a "global landscape" change for nuclear energy.
They could light up remote corners of the world, desalinate oceans into drinking water, power factories and propel ships, all while working hand-in-hand with renewable energy to mitigate climate change. The coming years will test whether the substantial promise of small modular reactors can be realized in practice.
Beyond 2040, if SMRs prove out, we might see a new paradigm where energy is produced in a mix of millions of solar panels, tens of thousands of wind turbines, and perhaps hundreds or thousands of small reactors, all orchestrated together to provide a reliable, clean energy supply for electricity, transportation, heating, and industry.
In this envisioned net-zero energy ecosystem, SMRs serve as the backbone of reliability and a source of high-quality heat for tough applications, complementing renewables which provide bulk cheap energy when nature allows. The world is watching these "small" reactors potentially make a big impact on our energy future.