Copenhagen Atomics is a fast-rising Danish nuclear engineering company focused on one goal: developing a factory-built molten salt thorium reactor (MSTR) that can deliver energy at a fraction of today’s cost. Founded by four engineers who converged around the potential of molten salt technology, the company has grown into a 65-person team with the world’s largest molten-salt testing facility and multiple full-scale prototype reactors already running in Copenhagen.

They began by tackling the hardest challenges: corrosion control, salt purification, high-temperature pumping systems and the chemical processing needed to remove fission products from liquid fuel. Their founders came from software, materials science and electrochemistry rather than the traditional nuclear industry, which has shaped their approach—rapid experimentation, modular engineering and a belief that nuclear reactors should be manufactured like industrial products rather than megaprojects.

Their long-term aim is to mass-produce standardized reactor units in a gigafactory, shipping one completed reactor per day. Each unit is the size of a 40-foot shipping container, designed to sit inside a protective steel “cocoon” built locally. A typical power plant would combine 25 units to deliver 1 gigawatt of electricity, with additional units for swapping and maintenance.

Key to enabling low costs is their “onion core” reactor geometry: a spherical, multi-layered design using heavy water moderation, a central fuel-salt region and an outer thorium blanket for breeding new fuel. This arrangement minimizes neutron losses and enables high breeding performance, which allows the reactor to run on thorium with only a small amount of enriched uranium as a startup charge.

By removing fission products continuously—starting with the easiest and expanding over time—they expect a major gain in neutron economy. This in turn reduces fuel requirements to just 36 kilograms of thorium per reactor per year once the system is operating in steady state.

All of this supports their target price of roughly $20 per megawatt hour of electricity, a level that could redefine global energy economics.

Copenhagen Atomics already operates full-scale, non-fission prototypes that use molten salts circulated at reactor-grade temperatures to test pumps, heat exchangers, materials and control systems. These test units are full commercial size and are cycled repeatedly to expose failure modes and reliability issues long before any nuclear operation begins.

Their next major milestone is a licensed 1-megawatt nuclear test reactor to be built and operated with the Paul Scherrer Institute (PSI) in Switzerland. The company is deep into the regulatory process, with first criticality targeted for 2027. After this demonstration, they expect to pursue licensing for their first commercial reactors, aiming for approvals around 2030.

The company is also scaling its fuel-salt production capability, including thorium and lithium-7 processing, and plans to support more than 100 reactor units from its current facility. Ultimately, they foresee gigafactories outside Europe—driven by demand, regulatory speed and investor interest.

If successful, Copenhagen Atomics could become one of the first companies to turn molten-salt thorium reactors from a half-century-old idea into a global industrial product.