Top 35 Nuclear Energy startups

Updated: Dec 30, 2025
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Nuclear energy startups are developing new reactor designs, such as small modular reactors (SMRs), molten salt reactors (MSRs) - to enhance safety, efficiency and waste management in the nuclear power industry.
1
Radiant
Country: USA | Funding: $518.8M
Kaleidos produces a portable nuclear microreactor that replaces diesel generators. It is a compact nuclear reactor (1 MW) with all the necessary equipment to generate electricity for remote villages and facilities, as well as backup power for hospitals and data centers. It requires no on-site water consumption thanks to the use of fans for air cooling. Helium conducts heat away from the core and does not become radioactive, eliminating the impact of leaks. Meltdown-resistant TRISO fuel, consisting of uranium particles coated with a ceramic coating, has been used in more than 30 grid-scale reactors since the 1960s. The reactor is assembled and fueled at the factory and delivered by truck or plane. Kaleidos mass-produces microreactors for US military bases.
2
Atomic Canyon
Country: USA | Funding: $7M
Atomic Canyon uses artificial intelligence to improve efficiency and optmize operations of nuclear power plants. The company is developing Neutron, an AI search engine for searching billions of pages of nuclear documentation. Using the Nuclear Regulatory Commission (NRC) database and the world's fastest supercomputer at Oak Ridge National Laboratory (ORNL), it understands and processes nuclear terminology with unprecedented accuracy, interpreting complex documents to let executives make more informed data-driven decisions. Neutron is based on open-source AI model FERMI intended for sentence vector representations, specifically designed for nuclear data. Atomic Canyon is working in partnership with PG&E's Diablo Canyon power plant, the only remaining nuclear power plant in California.
3
Last Energy
Country: USA | Funding: $164M
Last Energy builds small modular nuclear reactors that can be mass-produced. The company uses an older 20 MW reactor design developed by the government for a merchant ship. Such reactor is designed to operate without maintenance for its entire service life. It will be delivered to site in an all-metal vessel with a six-year supply of uranium. Heat from fission reactions heats the steel and water flowing through pipes outside uses this heat to spin a steam turbine. At the end of its service life, the steel vessel will serve as a waste container, eliminating the need for separate disposal. The company hopes that this approach, combined with advances in manufacturing, will lead to lower cost of nuclear energy. Last Energy is currently building a 5-megawatt pilot reactor and production of a 20-megawatt commercial reactor is scheduled to begin in 2028.
4
X-energy
Country: USA | Funding: $1.7B
X-energy produces the Xe-100 - small modular nuclear reactor. It is a fourth-generation, 80-megawatt high-temperature gas-cooled reactor (HTGR), boasting high stability, efficiency, reliability and safety. The reactor can be scaled into 4-pack power plant thanks to its modular design. Its construction maximizes the use of off-the-shelf components, that can be delivered to the site using existing road and rail routes. The reactor does not rely on any active systems, electrical power or human intervention for safety, i.e. it shuts down and dissipates heat passively (as a result of the low power density). X-energy also produces TRISO-X fuel, which can withstand extreme temperatures. X-energy also aims to produce power systems for lunar bases.
5
TerraPower
Country: USA | Funding: $1.4B
TerraPower is developing compact modular nuclear reactors with a closed fuel cycle. Its goal is to make nuclear energy safer and cheaper, while also minimizing radioactive waste. It was co-founded by Bill Gates and partners with GE Hitachi Nuclear Energy. Its sodium-cooled fast reactor, Natrium has capacity up to 345 MW, has a molten salt heat storage system and uses innovative liquid metal cooling. Its advantage is its flexible power output, allowing it to respond to fluctuating demand when combined with renewable energy sources. It uses liquid sodium as a coolant and highly enriched uranium (HALEU) as fuel (although the company is experiencing supply issues). The demonstration reactor project is expected to be operational by 2030.
6
Orano
Country: France | Funding: €900M
Orano offers customers customized solutions for every stage of nuclear energy production: from mining, conversion, enrichment, reprocessing, logistics and engineering to decommissioning and dismantling. The company operates uranium mines in Canada, Kazakhstan and Niger and is one of the world's leading uranium producers. It's offering competitive production costs and advanced recovery technologies. In addition to mining, Orano carries out exploration and development projects in uranium-bearing zones, as well as the rehabilitation and modernization of former mines. Orano is also a world leader in uranium processing, ensuring its customers the efficient, safe and responsible management of spent nuclear fuel. By recovering 96% of recycled materials (95% uranium and 1% plutonium) from spent fuel Orano can reprocess the material and produce new fuel, such as mixed oxide fuel (MOX) for nuclear reactors.
7
Newcleo
Country: UK | Funding: $677.1M
Newcleo develops small modular reactors (SMRs) that uses MOX fuel technology to reprocess spent uranium from conventional nuclear power plants. The 200 MW reactor uses lead as a coolant. This is an ultra-compact module with improved energy density compared to other technologies. MOX fuel, which stands for Mixed Pu-U Oxides consists of depleted uranium (a byproduct of the enrichment process in modern reactors) and plutonium (which is extracted from spent nuclear fuel). The company intends to use already available nuclear material in France in synergy with the in-country environment. Newcleo plans to install the first 30 MW lead-cooled fast reactor (LFR-AS-30) in Savigny-en-Véron and Beaumont-en-Véron.
8
Kairos Power
Country: USA | Funding: $629M
Kairos Power is developing advanced FHR reactor using granular TRI-Structural ISOtropic (TRISO) fuel in pebble form. The technology uses an efficient and flexible steam cycle to convert heat from fission into electricity. Instead of water, used in traditional nuclear reactors, the Kairos Power reactor uses molten fluoride salts as coolant, which has excellent chemical stability and high heat transfer capacity at high temperatures. The reactor requires no electrical power to remove heat from the core after shutdown and there is no need for coolant makeup (since the coolant cannot boil off). The fuel's resistance to extremely high temperatures provides orders of magnitude greater cooling capacity in emergency scenarios compared to water-cooled reactors. The company's goal is to build the Hermes 2 Demonstration Plant (50 MW) by 2030.
9
NuScale Power
Country: USA | Funding: $469.6M
NuScale Power has developed small modular reactor NuScale Power Module (NPM) - that was the first to receive design approval from the U.S. Nuclear Regulatory Commission. NPM design is based on proven pressurized water reactor technology and was developed to power power plants, district heating, desalination and industrial hydrogen production. The 77-megawatt reactor weighs 700 tons, allowing it to be shipped from the factory in three sections by truck, rail or barge. NuScale, in partnership with TVA and ENTRA1 Energy, is implementing a pioneering 6-GW SMR program to provide reliable, carbon-free electricity for the future of the seven-state TVA region. The company also established the Energy Research Center - an innovative educational environment offering users hands-on opportunities to apply nuclear science and engineering principles to simulated, real-world nuclear power plant scenarios.
10
Oklo
Country: USA | Funding: $440.6M
Oklo is building a container-sized, continuously operating, carbon-free and emissions-free fission nuclear reactor Aurora. It uses liquid metal coolant and metallic fuel, generates up to 75 MW, features built-in safety and can run on reprocessed waste. The reactor is self-stabilizing, self-regulating and cooled by natural forces. This means the plant is safe for personnel and the technology that enables this has been demonstrated at scale. Oklo also reprocesses nuclear fuel. The company has three project sites and the broadest regulatory support of any modern nuclear power system in the United States. OpenAI co-founder Sam Altman is the primary investor and even served as an early Oklo CEO.
11
Terrestrial Energy
Country: Canada | Funding: $280M
Terrestrial Energy creates Integral Molten Salt Reactor plants that capture the full advantages of molten salt fission technology and the superiority of a molten salt as a reactor coolant.
12
Aalo Atomics
Country: USA | Funding: $136M
Aalo makes small, factory-manufactured nuclear reactors that can fit in your garage, and power anything from a datacenter to a large city.
13
Antares
Country: USA | Funding: $126M
Antares designs and builds microfission reactors for strategic energy applications, including space missions, commercial and military energy resilience. The R1 microreactor can produce from 100 kilowatts to 1 megawatt and uses TRISO fuel, which consists of uranium spheres coated with carbon and ceramics, embedded in graphite. The company performs high-precision machining of the nuclear graphite in-house, speeding design iterations. The optimized reactor design simplifies deployment with a minimal number of actuators. The control drums, made of graphite and boron carbide, have independent actuators, inspired by the designs of historical space reactors. Antares has a manufacturing facility in California and has already tested the first electrically heated demonstration unit (EDU).
14
Zeno Power
Country: USA | Funding: $94.9M
Zeno is developing next-generation radioisotope power systems that generate carbon-free, resilient power for decades.
15
Saltfoss
Country: Denmark | Funding: $60M
Saltfoss develops the Compact Molten Salt Reactor - a smal modular reactor based on molten fluoride salt.
16
The Nuclear Company
Country: USA | Funding: $51M
The Nuclear Company is a fleet-scale nuclear development company using proven technology to construct a series of nuclear power plants across America.
17
Standard Nuclear
Country: USA | Funding: $46.5M
Standard Nuclear is a reactor-agnostic producer of TRISO nuclear fuel.
18
Thorizon
Country: Netherlands | Funding: €42.5M
Thorizon aims to develop a new generation of nuclear power plants - molten salt reactors.
19
Blue Energy
Country: USA | Funding: $45M
Blue Energy is a nuclear power plant company that provides reliable, clean, and abundant electricity.
20
Transmutex
Country: Switzerland | Funding: $43.5M
Transmutex develops technology designed to reduce the stockpile of nuclear waste-based energy.
Alexander Gillet
Editor: Alexander Gillet
Alexander Gillet is a senior editor for EnergyStartups. He has a deep background in energy sector and startups. Alexander graduated from Emlyon Business School, a leading French business school specialized in entrepreneurship. He has helped several non-profit organizations dedicated to promoting environmental education and sustainability and has written over 250 articles on energy technology for various websites. In his free time, Alexander enjoys yoga, camping and exploring the Blue Ridge Mountains. You can contact Alexander at alexgillet(at)energystartups(dot)com