Copenhagen Atomics

Copenhagen Atomics is a Danish nuclear technology company focused on the development of mass-manufacturable molten-salt reactors and associated components. The company emerged from discussions among scientists and engineers connected with the Technical University of Denmark and the wider Copenhagen technology community. Those discussions began in 2014, and the company was incorporated in 2015. Its work centers on small modular reactors using liquid fuel salts, a thorium fuel cycle, a thermal neutron spectrum, and breeder-reactor principles. The company’s proposed reactor architecture is designed around multiple concentric functional layers. A thorium-bearing blanket salt is intended to support the conversion of thorium into uranium-233, while a separate pumped fuel salt acts as both the reactor fuel and coolant. Heavy water is used as a moderator, and the system is designed to operate with high-temperature molten salts. Copenhagen Atomics has also described the use of separated plutonium from spent nuclear fuel as the initial fissile material for the first generation of reactors. The design requires the continuous or online removal of fission products while the reactor is operating. Rather than concentrating only on a complete commercial reactor design, Copenhagen Atomics follows a hardware-led, iterative development model. It develops and tests individual systems such as pumps, valves, heat exchangers, instrumentation, salt chemistry, purification equipment, control systems, and software for molten-salt applications. This approach is intended to build practical operating experience with difficult high-temperature and chemically aggressive environments before broader reactor deployment. The company has developed a canned molten-salt pump and is working on an active electromagnetic-bearing version. It also makes or offers technology for molten-salt research, including pumped salt loops and highly purified salts. These products and components can serve research into molten-salt reactors, concentrated solar power, thermal energy storage, and high-temperature salt chemistry, giving the company activities beyond a single reactor product. Copenhagen Atomics participated in the European MIMOSA molten-salt research consortium in 2016 and became the first private company reported to offer a commercial molten-salt loop in 2017. By the end of 2022 it had completed a full-size prototype reactor platform that used water to test the overall system. A full-scale prototype using non-radioactive molten salts was built in 2023, allowing the company to test the integrated system under more representative thermal and chemical conditions without operating a nuclear chain reaction. The company has also pursued industrial applications for nuclear heat and low-carbon energy. In May 2023 it signed a memorandum of understanding with Scandinavian industrial companies Topsoe, Alfa Laval, and Aalborg CSP, together with Indonesian companies Pupuk Kalimantan Timur and Pertamina New and Renewable Energy. The proposed cooperation concerned a green-ammonia facility in Bontang, Indonesia, illustrating Copenhagen Atomics’ interest in coupling advanced nuclear technology with industrial heat and chemical production. In 2023, the company moved from Alfa Laval’s Innovation House to a dedicated headquarters and production facility in Kastrup. In July 2024 it announced that its prototype reactors were intended for a critical experiment at the Paul Scherrer Institute in Switzerland. The proposed experiment would represent an important step from non-nuclear system testing toward testing a thorium molten-salt reactor configuration in a research environment. Copenhagen Atomics remains a development-stage nuclear technology business, and the timing, licensing, financing, and commercial deployment of any future reactor remain subject to technical and regulatory progress.

Copenhagen Atomics was formed from a group of scientists and engineers who began meeting in 2014 around the Technical University of Denmark and the Copenhagen area to discuss thorium energy and molten-salt reactor technology. The company was incorporated in 2015. From the beginning, its work was directed toward reactor concepts that could be manufactured in series, rather than toward a one-off demonstration plant. Its technical program combines small modular reactor ambitions with liquid fuel salts, a thorium breeding cycle, a thermal neutron spectrum, and the use of separated plutonium from spent nuclear fuel as the initial fissile load for an intended first generation. In 2016, Copenhagen Atomics participated in MIMOSA, a European research consortium concerned with molten-salt nuclear technology. The following year, it became the first private company reported to offer a commercial molten-salt loop. This reflected a development strategy centered on practical hardware and test infrastructure. Instead of relying solely on a complete reactor design and a conventional full-system licensing pathway at an early stage, the company has emphasized component-by-component experimentation. Its development work has included pumps, valves, heat exchangers, measurement equipment, salt chemistry, purification systems, reactor controls, and software. The proposed reactor is described as having a layered or onion-like core. An outer breeding blanket containing lithium-fluoride and thorium-fluoride salts is intended to support the production of uranium-233 from thorium. Inside that region are layers of heavy water used for moderation, together with a pumped lithium-7-fluoride and uranium-tetrafluoride fuel salt. The fuel salt is expected to circulate at high temperature and serves both as the fuel medium and coolant. The company’s concept also requires online processing to remove fission products while the reactor operates. Early designs use stainless steel between functional layers, while later materials may include silicon-carbide composites and ceramic insulation. Copenhagen Atomics has developed a canned molten-salt pump and has worked on an active electromagnetic-bearing version. The company also develops commercial research equipment, including pumped molten-salt loops and purified salts. These offerings can be used in nuclear research as well as in concentrated solar power, molten-salt thermal storage, and high-temperature chemical experimentation. The broader component business provides a way to commercialize engineering capabilities while the reactor program remains in development. By the end of 2022, Copenhagen Atomics had completed a full-size prototype reactor platform. This first platform used water as its medium and was intended to test the complete system architecture. In 2023, the company built a full-scale prototype using non-radioactive molten salts, permitting more representative testing of pumps, salt circulation, thermal systems, instrumentation, and control functions without conducting a nuclear reaction. The same year, the company relocated from Alfa Laval’s Innovation House to a dedicated headquarters and production facility in Kastrup. Copenhagen Atomics has also explored the possible use of advanced nuclear energy in industrial production. In May 2023, it signed a memorandum of understanding with Scandinavian companies Topsoe, Alfa Laval, and Aalborg CSP and Indonesian companies Pupuk Kalimantan Timur and Pertamina New and Renewable Energy. The proposed collaboration concerned a green-ammonia facility in Bontang, Indonesia, with the stated objective of combining low-emission energy with large-scale ammonia production. In July 2024, Copenhagen Atomics announced plans for a critical experiment at the Paul Scherrer Institute in Switzerland. The proposed experiment would be a significant transition from non-radioactive engineering demonstrations to research involving a critical thorium molten-salt reactor configuration. The company remains a technology developer rather than a commercial nuclear utility. Its future progress depends on successful testing, safety and regulatory approvals, supply-chain development, financing, and acceptance by industrial and national authorities.

• 2024

  Swiss critical-experiment plans announced

  [1]Copenhagen Atomicsen.wikipedia.org

  The company announces that its prototype reactors are intended for a critical experiment at the Paul Scherrer Institute in Switzerland.

• 2023

  Full-scale molten-salt prototype built

  [1]Copenhagen Atomicsen.wikipedia.org

  The company builds a full-scale prototype using non-radioactive molten salts.

• 2023

  Relocation to Kastrup

  [1]Copenhagen Atomicsen.wikipedia.org

  Copenhagen Atomics moves to new headquarters and production facilities in Kastrup.

• 2022

  Full-size water-based prototype completed

  [1]Copenhagen Atomicsen.wikipedia.org

  A full-size prototype platform is completed for integrated system testing using water as the medium.

• 2017

  Commercial molten-salt loop offering

  [1]Copenhagen Atomicsen.wikipedia.org

  Copenhagen Atomics becomes the first private company reported to offer a commercial molten-salt loop.

• 2016

  Participation in the MIMOSA consortium

  [1]Copenhagen Atomicsen.wikipedia.org

  The company participates in MIMOSA, a European consortium researching molten-salt nuclear technology.

• 2015

  Company incorporated

  [1]Copenhagen Atomicsen.wikipedia.org

  Copenhagen Atomics is incorporated as a company focused on thorium and molten-salt reactor technology.

• 2014

  Founding discussions begin

  [1]Copenhagen Atomicsen.wikipedia.org

  Scientists and engineers associated with the Technical University of Denmark and the Copenhagen area begin developing the ideas that lead to Copenhagen Atomics.

A development-stage advanced nuclear technology company focused on scalable molten-salt reactors, thorium fuel-cycle research, component engineering, and industrial applications of high-temperature energy.

• Advanced nuclear reactor

  Copenhagen Atomics molten-salt reactor platform

  The company’s central technology program is a small modular molten-salt reactor concept using liquid fuel salt, a thorium breeding blanket, heavy-water moderation, and a thermal-spectrum breeder configuration. The concept is designed for high-temperature operation and online removal of fission products. Copenhagen Atomics has pursued full-scale non-radioactive prototypes to test the integrated mechanical, thermal, chemical, measurement, and control systems before any commercial deployment.

• Nuclear research equipment · 2017

  Pumped molten-salt loops

  Pumped molten-salt loops are test systems for circulating high-temperature salts and evaluating components used in molten-salt reactors. Copenhagen Atomics became known for offering a commercial molten-salt loop and uses this type of equipment to support research into salt flow, heat transfer, chemistry, purification, instrumentation, and control. The loops may also be relevant to non-nuclear applications involving high-temperature salts.

• Reactor component

  Canned molten-salt pumps

  The company has developed a canned molten-salt pump for handling hot circulating salt while limiting leakage and exposure of the working fluid to the surrounding environment. It is also developing an active electromagnetic-bearing canned pump. These components address one of the demanding engineering problems in molten-salt systems: reliable circulation of corrosive, high-temperature fluids.

• Specialty materials

  High-purity molten salts

  Copenhagen Atomics offers highly purified salts for applications including molten-salt reactor research, concentrated solar power, thermal energy storage, and molten-salt chemistry. Salt purity and composition are important because impurities can affect corrosion, neutron behavior, heat transfer, pump operation, and the long-term stability of high-temperature systems.

• 2023Bontang green-ammonia cooperation

  Indonesia · Denmark · Scandinavia

  Copenhagen Atomics joined Topsoe, Alfa Laval, Aalborg CSP, Pupuk Kalimantan Timur, and Pertamina New and Renewable Energy in a memorandum of understanding concerning a proposed green-ammonia plant in Bontang, Indonesia. The project was presented as an industrial application for very-low-emission energy and heat.

  Outcome. The material describes a memorandum and proposed project, not a completed commercial plant.

  Source

• 2024

  Prepare prototypes for a Swiss critical experimentOther

  Background

  Following non-radioactive system testing, the company sought to move its technology toward a research experiment involving a critical thorium molten-salt reactor configuration.

  Action taken

  Copenhagen Atomics announced plans for prototype testing in a critical experiment at the Paul Scherrer Institute in Switzerland.

  Aftermath

  The proposed experiment would represent a major technical milestone, but the cited material does not establish that it has been completed.

  Source

• 2023

  Adopt an integrated prototype-testing pathwayStrategy

  Background

  After completing a water-based full-size prototype, Copenhagen Atomics pursued testing with non-radioactive molten salts to evaluate the system under more representative operating conditions.

  Action taken

  The company built a full-scale non-radioactive molten-salt prototype and continued component-level testing of pumps, heat exchangers, salt chemistry, controls, and instrumentation.

  Aftermath

  The prototype provided a bridge between laboratory component work and a proposed future critical experiment, without constituting commercial reactor operation.

  Source

• 2017

  Commercialize molten-salt test infrastructureStrategy

  Background

  The company’s development program required practical testing of molten-salt components and systems rather than relying only on theoretical reactor design.

  Action taken

  Copenhagen Atomics offered a commercial pumped molten-salt loop, making part of its engineering and testing capability available to external users.

  Aftermath

  The company expanded its activity beyond a future reactor product into research equipment and component technology.

  Source

1. 1Copenhagen Atomicsen.wikipedia.org