1
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 (according to the company) 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. The company also aims to produce power systems for lunar bases.
X-energy produces the Xe-100 - small modular nuclear reactor. It is a fourth-generation, 80-megawatt high-temperature gas-cooled reactor (HTGR), boasting (according to the company) 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. The company also aims to produce power systems for lunar bases.
2
Country: USA | Funding: $1.5B
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 fast-neutron reactor Natrium has capacity up to 345 MW and includes molten salt heat storage system. 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 (for now the company is experiencing supply issues). The demonstration reactor project is expected to be operational by 2030.
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 fast-neutron reactor Natrium has capacity up to 345 MW and includes molten salt heat storage system. 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 (for now the company is experiencing supply issues). The demonstration reactor project is expected to be operational by 2030.
3
Country: UK | Funding: $677.1M
Newcleo develops small modular reactor that uses MOX fuel technology to reprocess spent uranium from conventional nuclear power plants. The 200 MW reactor uses lead as a coolant. It's an ultra-compact module with improved energy density compared to other technologies. The company also produces FR-MOX fuel (Fast Reactors Mixed Pu-U Oxides) which consists of depleted uranium (a byproduct of the enrichment process in modern reactors) and plutonium (which is extracted from spent nuclear fuel). Thus it intends to close the fuel cycle and avoid mining. Newcleo plans to install the first 30 MW lead-cooled fast reactor in France by the end of 2033.
Newcleo develops small modular reactor that uses MOX fuel technology to reprocess spent uranium from conventional nuclear power plants. The 200 MW reactor uses lead as a coolant. It's an ultra-compact module with improved energy density compared to other technologies. The company also produces FR-MOX fuel (Fast Reactors Mixed Pu-U Oxides) which consists of depleted uranium (a byproduct of the enrichment process in modern reactors) and plutonium (which is extracted from spent nuclear fuel). Thus it intends to close the fuel cycle and avoid mining. Newcleo plans to install the first 30 MW lead-cooled fast reactor in France by the end of 2033.
4
Country: USA | Funding: $164M
Last Energy builds small modular nuclear reactors that can be mass-produced. The company uses an older 20 MW PWR-reactor design developed by the government for a merchant ship. The 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. It is currently building a 5-megawatt pilot reactor while the production of a 20-megawatt commercial reactor is scheduled to begin in 2028.
Last Energy builds small modular nuclear reactors that can be mass-produced. The company uses an older 20 MW PWR-reactor design developed by the government for a merchant ship. The 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. It is currently building a 5-megawatt pilot reactor while the production of a 20-megawatt commercial reactor is scheduled to begin in 2028.
5
Country: Netherlands | Funding: €42.5M
Thorizon is building a molten salt modular reactor to power industry, data centers and Europe's energy independence. It was founded as a spin-off from the Netherlands’ national nuclear research institute, where molten salt technology was developed quietly for decades. The reactor will use nuclear waste as fuel and provide both power and high‑temperature heat with sufficient safety. Thorizon’s patented cartridges divide the reactor core into smaller modules, unlocking the benefits of off-site series production and modular scalability. Easy to operate, move, and deploy, these cartridges make building reactors faster and more flexible than ever. The first plant construction will start in the early 2030s.
Thorizon is building a molten salt modular reactor to power industry, data centers and Europe's energy independence. It was founded as a spin-off from the Netherlands’ national nuclear research institute, where molten salt technology was developed quietly for decades. The reactor will use nuclear waste as fuel and provide both power and high‑temperature heat with sufficient safety. Thorizon’s patented cartridges divide the reactor core into smaller modules, unlocking the benefits of off-site series production and modular scalability. Easy to operate, move, and deploy, these cartridges make building reactors faster and more flexible than ever. The first plant construction will start in the early 2030s.
6
Country: Denmark | Funding: $33.6M
Copenhagen Atomics is developing thorium molten salt reactor technology, with a focus on low electricity prices and fast installation. Its first test reactor (planned for 2028) and first commercial reactors (planned for 2030s) will run on 5% enriched uranium as fuel salt and thorium as blanket salt. With high enriched Li7 for optimal neutron economy, CAs reactors will have better neutron economy than any other reactor ever designed or build (according to the startup). The first reactors will not be breeder reactors, meaning that they will generate more fissile fuel than they consume. But they will have breeding ratio approaching 1. In the long term CA wishes to make thorium breeder reactors in the thermal spectrum (slow neutrons). CA has also invented the Onion Core technology, enabling a compact reactor that can be mass-manufactured efficiently while requiring only a small amount of materials.
Copenhagen Atomics is developing thorium molten salt reactor technology, with a focus on low electricity prices and fast installation. Its first test reactor (planned for 2028) and first commercial reactors (planned for 2030s) will run on 5% enriched uranium as fuel salt and thorium as blanket salt. With high enriched Li7 for optimal neutron economy, CAs reactors will have better neutron economy than any other reactor ever designed or build (according to the startup). The first reactors will not be breeder reactors, meaning that they will generate more fissile fuel than they consume. But they will have breeding ratio approaching 1. In the long term CA wishes to make thorium breeder reactors in the thermal spectrum (slow neutrons). CA has also invented the Onion Core technology, enabling a compact reactor that can be mass-manufactured efficiently while requiring only a small amount of materials.
