This article has been updated to include ten of the world’s leading small modular reactor companies.

Small modular reactors (SMRs) are disrupting conventional notions surrounding nuclear power. Smaller, more compact, and producing minimal emissions, this innovative alternative to traditional nuclear power is receiving more public and private sector attention as governments scramble to meet global energy needs reliably and responsibly. 

According to Polaris Market Research, the global market for SMRs was valued at approximately $9.88 billion in 2023 and is projected to grow at a compound annual growth rate (CAGR) of 3.6% until 2032, up from just $3.5 billion in 2020. While the SMR market is full of many innovative companies, here are ten small modular reactor companies to look out for as we enter the new year. 

X-Energy

X-Energy is a private nuclear reactor and fuel design engineering company based in Rockville, MD. It was founded in 2009 by Iranian-born American businessman Kam Ghaffarian. Ghaffarian is also the founder of several high-profile companies, including Axiom Space, IBX, Intuitive Machines, and Quantum Space. 

X-Energy’s flagship technology is the Xe-100 reactor, a high-temperature gas-cooled reactor. The Xe-100 reactor has a base capacity of 80 MWe but can be configured into a “four-pack” system to deliver up to 320 MWe, with the flexibility to expand further, thanks to its modular design. Xe-100 contains 220,000 Graphite Pebbles with TRISO Particle fuel. TRISO particles are described as “the most robust nuclear fuel on Earth,” according to the U.S. Department of Energy. One noted benefit of this type of reactor technology is the ability to withstand extreme temperatures; Xe-100 operates at temperatures above 750°C. X-Energy manufactures its proprietary version of the fuel dubbed “TRISO-X.” 

In October 2024, Amazon led a Series C-1 financing round for X-Energy that raised $500 million. Ken Griffin, the founder and CEO of Citadel and affiliates of Ares Management Corporation, private equity firm NGP, and the University of Michigan, participated as investors alongside Amazon’s Climate Pledge Fund in the funding round. Amazon also pledged financial support for a four-unit 320-megawatt project with regional utility Energy Northwest in central Washington, with an option of expanding the project to 12 units, yielding a total capacity of 960 MW.

Amazon’s investment is the most notable yet because the company directly financed the construction of the reactors rather than merely agreeing to buy power from them. For nuclear to play a significant role in America’s future energy landscape, moving beyond pledges and commitments requires substantial private sector investment and a willingness to take on risk. Amazon’s financial backing is a significant step in that direction. 

Oklo

Santa Clara-based Oklo is an advanced nuclear tech company founded in 2013 by two Massachusetts Institute of Technology graduates, Jacob DeWitte and Caroline Cochran. The company designs next-generation fission power plants that produce abundant, affordable clean energy. ​​

Oklo’s technology builds off of years of trial and error. Oklo deliberately chose a liquid-metal-cooled, metal-fueled fast reactor due to its extensive demonstration history, supported by 400 reactor-years of global operating experience—making it the most proven of all advanced fission technologies. The technology is also inherently safe; the reactor is self-stabilizing, self-controlling, and cooled by natural forces. Tests conducted with EBR-II (the successor to the first fission power plant, EBR-I) demonstrated that the reactor could naturally stabilize and safely shut down without sustaining damage, even if the coolant was turned off and all shutdown systems were disabled.

Oklo made history by obtaining the first permit for an advanced reactor site and submitting an inaugural combined license application for an advanced reactor. Oklo’s team includes experts with experience from renowned companies such as Apple, Tesla, Netflix, SpaceX, Google, and Boeing.

Sam Altman, co-founder and CEO of OpenAI, is chairman of Oklo. Chris Wright, Donald Trump’s nominee for Energy Secretary, also served on the company’s board before resigning to avoid conflict of interest. The company went public in May 2024. 

TerraPower

Nuclear innovation company TerraPower was founded in 2008 by Bill Gates and other private sector leaders. The company is now recognized as an international leader in the SMR space, having secured a whopping $80 million in federal funding from the U.S. Department of Energy (DOE) in 2020 to support the development of its groundbreaking Natrium nuclear reactor. In 2021, TerraPower selected Kemmerer, Wyoming, as the preferred site for its advanced nuclear reactor demonstration plant. The Natrium reactor is one of just two competitively-selected advanced reactor demonstration projects (ARDP) supported by the Department of Energy.  

As of December 2024, TerraPower is progressing significantly with its Natrium reactor project. Construction on the Natrium reactor demonstration project began in June, making it the first advanced reactor project to move from design into construction. TerraPower’s construction permit application for the Natrium reactor is under review by the U.S. Nuclear Regulatory Commission (NRC). According to TerraPower, due to the Natrium reactor’s unique design, non-nuclear construction of the plant will begin before the NRC approves the nuclear components. 

Westinghouse Electric Company 

Leading SMR company Westinghouse Electric propelled to the forefront of the nuclear technology industry with its transportable eVinci™ microreactor. More of a nuclear battery than a traditional nuclear reactor, the high-temperature heat pipe reactor can generate 5 MW of electricity and up to 13 MW of heat from its 15 MW solid thermal core. 

The mobile nuclear power plant generates power from its advanced heat pipe technology and unique core design. The self-regulating heat pipes enable passive heat transfer, allowing for autonomous operation and inherent load following. According to Westinghouse, the reactor core is designed to operate in full power mode for eight or more years before refueling.

The eVinci microreactor can be fully factory built, fueled, and assembled. A plug-and-play interface allows for rapid on-site installation in less than 30 days. eVinci can operate on or off the grid in all weather conditions and temperatures. The company claims the deployable energy generator is ideal for industrial applications and district heating. 

In November 2024, Westinghouse and the UK-based maritime nuclear innovation firm CORE POWER announced a partnership to design and develop a floating nuclear power plant (FNPP) using the eVinci™ microreactor. In December 2024, the Westinghouse eVinci™ microreactor became the first and only microreactor in the market with an NRC-approved instrumentation and control (I&C) system. The specialized I&C platform manages the reactor’s safety-critical systems using hardware-based logic rather than software or computer chips. This innovative approach is an industry first, reducing the need for human intervention and paving the way for more autonomous operation in microreactors. 

Kairos Power

SMR maker Kairos Power is betting on high-temperature molten salt reactors to provide competitive, reliable, and responsible nuclear energy. According to U.S. Energy Information Administration data, the company touts its fluoride salt-cooled high-temperature reactors (KP-FHR) as an affordable and long-term alternative to conventional energy sources like natural gas, the country’s primary fuel of choice. 

The KP-FHR is a novel SMR technology with a near-zero carbon footprint and minimal water consumption, featuring an accident-resistant design and dispatchable reactor. Kairos is poised to meet rising U.S. electricity demand with its innovative high-purity fluoride salt-powered technology. According to Kairos Power co-founder and CEO Mike Laufer, the company aims to complete an initial demonstration of its advanced nuclear reactor design by 2030 the earliest. 

In October 2024, Google announced a new agreement to purchase nuclear energy from Kairos Power. The project’s first phase aims to bring Kairos Power’s first SMR online by 2030, with additional reactors (around six or seven) to be deployed by 2035. The initiative will contribute up to 500 MW of new, round-the-clock, carbon-free energy to U.S. electricity grids, expanding access to clean and affordable nuclear power for more communities. Some of the energy generated by the reactors will also be used to power Google’s AI data centers as the company bets big on generative AI.

“The grid needs new electricity sources to support AI technologies that are powering major scientific advances, improving services for businesses and customers, and driving national competitiveness and economic growth,” Michael Terrell, the senior director for energy and climate at Google, wrote in the announcement. “This agreement helps accelerate a new technology to meet energy needs cleanly and reliably and unlock the full potential of AI for everyone.”

Google heralded the deal as the world’s first corporate purchase agreement for nuclear energy from SMRs. 

BWXT Advanced Technologies 

SMR developer BWXT Technologies will build the first advanced nuclear microreactor in the United States. The U.S. Department of Defense’s (DoD) Strategic Capabilities Office selected the nuclear solutions firm in 2022 to manufacture a full-scale mobile microreactor prototype for testing at the Idaho National Laboratory (INL). Construction on the Project Pele microreactor kicked off in September 2024, according to an announcement from the DOD’s Office of Nuclear Energy. The reactor is currently being manufactured by BWXT as part of the Strategic Capabilities Office (SCO) initiative, with the assembly of the final reactor set to begin in February 2025. BWXT expects the final product to be fully assembled and ready for delivery to INL in 2026. 

Nuscale

This advanced nuclear reactor company–which went public in 2022– is leading several large-scale projects across Central and Eastern Europe. NuScale is particularly active in Poland, where it will build its flagship VOYGR SMR power plant with up to 924 MWe of electricity as early as 2029. Poland, a newcomer in the nuclear technology market, chose Portland, Oregon–based NuScale to develop and construct the country’s first small modular reactor. The historic agreement comes from an ambitious multi-nation decarbonization plan signed in Glasgow last November by 28 new Powering Past Coal Alliance (PPCA members). The eastern European nation generated about 70% of its electricity from coal in 2020, according to a 2021 report from Forum Energii.

In August 2024, Ghana and Regnum Technology Group formalized an agreement to deploy a NuScale VOYGR-12 SMR during a U.S.-Africa nuclear energy summit in Nairobi. The agreement marks a significant step in adopting nuclear technology in developing countries, offering a potential solution for clean, reliable, and scalable energy worldwide. 

Holtec International 

Holtec International is another world-class developer of SMRs. The company boasts two SMR designs: the SMR-160 and the SMR-300. According to the U.S. Nuclear Regulatory Commission, the SMR-160 is a pressurized water reactor (PWR) featuring passive safety systems and an electrical capacity of 160 MWe. The company has temporarily suspended its pre-application activities for the SMR-160 to focus on the SMR-300, its latest reactor design. The SMR-300 is a next-generation, passively safe, pressurized light water nuclear power plant with a net electrical output of 300 MWe. The reactor requires no active intervention from operators, controlled equipment, or external power, even in severe natural disasters or man-made threats.

In August 2024, Holtec Britain, a subsidiary of Holtec International USA, completed the first phase of the UK Generic Design Assessment process for Holtec’s SMR-300 nuclear reactor, setting a new regulatory approval record of ten months. The SMR-300 is designed and manufactured at Holtec’s Krishna P. Singh Technology Campus in Camden, New Jersey, and the company plans to expand in the UK. 

GE Hitachi Nuclear Energy

GE Hitachi Nuclear Energy (GEH), headquartered in Wilmington, NC, has been a leading advanced reactors and nuclear services provider for over 60 years. Its latest innovation is the BWRX-300, a boiling water reactor with 300 MW of carbon-free power. The BWRX-300 is a compact technology that utilizes natural circulation and passive cooling through isolation condenser systems for supreme safety and simplicity. It can be constructed within 24 to 36 months, making it suitable for retrofitting or replacing existing coal-fired power plants with nuclear technology. 

BWRX-300 delivers up to a 60% reduction in capital costs per megawatt, offering greater affordability than conventional water-cooled SMRs. In January 2024, GEH obtained a £33.6 million (approximately USD 41.5 million) grant from the UK Department for Energy Security & Net Zero under the Future Nuclear Enabling Fund (FNEF) to support the UK’s decarbonization goals. 

GEH operates 67 reactors licensed across ten countries. It also holds over 6,660 patents worldwide. 

General Atomics

General Atomics (GA) is a defense and diversified technologies firm headquartered in San Diego, CA. Besides its numerous defense applications, such as unmanned aircraft systems, radar systems, and other military technologies, GA has been a leader in nuclear energy innovation since its founding in 1955. General Atomics Electromagnetic Systems (GA-EMS), a subdivision of General Atomics, develops pioneering advanced reactors like the GA-EMS’ Energy Multiplier Module (EM2), a cutting-edge, gas-cooled SMR designed to tackle four of the biggest challenges in nuclear energy: cost, safety, waste management, and nonproliferation.

EM2 is a fast reactor cooled by helium, featuring a core outlet temperature of 850°C. Designed as a modular power source capable of connecting to the grid, the reactor has a net output of 265 MWe per unit. The reactor uses a “convert and burn” strategy, enabling it to operate for 30 years without fuel replacement.

GA claims that the EM2 generates 60% more electricity from the same amount of heat than existing reactors while producing only one-fifth of the waste generated by current light water reactors. Additionally, EM2 requires no external electricity source to maintain passive safety and uses inert helium gas instead of water, further improving the safety of already safe technology.

GA is in the early stages of developing four separate performance models to support its SiGA silicon-carbide (SiC) composite nuclear fuel cladding technology. This technology will improve the efficiency, safety, and longevity of the fuel used in the EM2 reactor. In January 2024, GA was awarded a three-year contract from the DOE to advance SiGA as part of the NRC’s Accident Tolerant Fuel Program.

Idaho National Laboratory 

While not a company, Idaho National Laboratory (INL) has been an essential resource for developing SMRs. As one of the 17 national laboratories within the U.S. Department of Energy network, INL has more than 6,100 researchers and support staff dedicated to driving progress and innovation in nuclear research. INL acts as a testing ground for emerging energy technologies, helping to spearhead advancements in the field and serving as an essential intermediary for translating innovative concepts from raw ideas into reality. The lab routinely partners with government agencies and private companies to test, validate, develop, and design trailblazing reactor fuels and technologies. 

INL also manages the world’s foremost materials test reactor, the Advanced Test Reactor, one of two reactors in the nation that manufacture life-saving medical-grade isotopes. 

A Bright Future for SMRs 

SMRs offer governments worldwide a chance to reduce emissions and provide reliable power to consumers. Thanks to innovators like those listed above, SMRs are quickly getting ready to be deployed globally.  

The views and opinions expressed are those of the author’s and do not necessarily reflect the official policy or position of C3.