Danish molten salt reactor developer Copenhagen Atomics, and Switzerland’s Paul Scherrer Institute (PSI), have signed a large-scale experimental collaboration agreement for a thorium molten salt critical experiment. The purpose of this experiment is to validate the technology and provide valuable experience for the collaboration partners in the design, construction, licensing, operation, and decommissioning of new molten salt reactor technology. It will also collect data for commercial deployment using open-source data for validation of reactor modelling tools.

Copenhagen Atomics has been developing its thorium molten salt reactor (TMSR) technology for almost a decade and has now matured the technology to the point where thorium molten salt critical experimental testing is needed. The company is already producing and testing full-scale test reactor prototypes at its headquarters in Copenhagen along with dozens of smaller-scale loop tests and salt production. Copenhagen Atomics’ molten salt reactor designs use lithium, thorium and low-enriched uranium fluoride salt as the reactor fuel and can be factory manufactured in modules the size of a 40ft shipping container.

PSI, the largest research institute for natural and engineering sciences in Switzerland, conducts research in four main fields: future technologies, energy and climate, health innovation and fundamentals of nature. PSI develops, builds and operates complex large research facilities and is Switzerland’s centre of excellence in nuclear energy research and safety. It operates a hot laboratory equipped for work and research on radioactive material. PSI said it is looking forward to a valuable collaboration with Copenhagen Atomics.

The collaboration agreement runs initially for four years. The partnership aims to conduct a thorium molten salt critical experiment in 2026. Copenhagen Atomics said the experiment will provide valuable experience for the design, construction, licensing, operation and decommissioning of the new MSR technology and collect data for commercial deployment.

Copenhagen Atomics was founded in 2014 by a group of scientists and engineers meeting at Technical University of Denmark and around the greater Copenhagen area for discussions on thorium and molten salt reactors, who incorporated in 2015. The following year, the company became part of European nuclear molten salt research consortium MIMOSA.

The company markets some of their technologies commercially including pumped molten salt loops for use in molten salt reactor research, as well as highly purified salts for high temperature concentrated solar power, molten salt energy storage, and molten salt chemistry research.

In 2022, the company raised €20m ($21.2m) to accelerate the development of its thorium molten salt reactor technology. Co-founder Thomas Jam Pedersen said the funding will support its plans to have the first commercial reactors online in 2028. In 2023, Copenhagen Atomics applied for its containerised small modular thorium molten salt reactor design to undergo Generic Design Assessment in the UK.