Copenhagen Atomics achieves a milestone in pump testing.

Danish nuclear technology firm Copenhagen Atomics has successfully completed two years of uninterrupted operation of a molten salt pump and testing loop at its Copenhagen facilities. This system has functioned smoothly under high-temperature molten salt conditions, representing one of the longest continuous durability tests of its type globally, according to the company.

Molten salt reactors (MSRs) depend on pumps to circulate liquid fuel or coolant at temperatures above 600°C for extended periods. Therefore, proving long-term, stable pump performance is essential for obtaining regulatory approval and facilitating commercial deployment, the company stated.

The pump under evaluation is part of Copenhagen Atomics' pumped molten salt loop platform, a comprehensive testing system designed to mimic the thermal, chemical, and mechanical conditions of future reactors, while not involving nuclear fission. By running multiple molten salt loops in parallel, the company can accumulate operational hours, refine designs, and generate statistically reliable data for pumps, valves, heat exchangers, and sensors. To date, Copenhagen Atomics has gathered more than 100,000 hours of combined pump runtime, with numerous pumps surpassing one year of operation.

Copenhagen Atomics designs and manufactures its pumps, control electronics, sensors, and test loops in-house and produces highly purified molten salts on a large scale. This vertically integrated approach enables the company to conduct long-duration tests at a significantly lower cost compared to national laboratories or large research facilities.

The company indicated that the two-year continuous operation "shows that molten salt pumps can function reliably over timeframes relevant to future commercial reactors, which is a crucial challenge for the technology overall."

"Reliability of components isn't something that can be proven just once; it must be demonstrated repeatedly over extended periods and in realistic conditions," remarked Copenhagen Atomics CEO and co-founder Thomas Jam Pedersen. "Operating a molten salt pump continuously for two years is a significant technical achievement, confirming that our design, material choices, salt purity, and testing methods are effective."

"For regulators, empirical data is crucial—not mere optimism or simulations. Extended component testing significantly mitigates risk later in the development phases. Identifying and addressing issues in a test loop is vastly less expensive than doing so in a prototype reactor."

Copenhagen Atomics plans to enhance its testing capacity in the upcoming years, aiming to operate dozens of molten salt loops in parallel, both in Copenhagen and with partner institutions. The company is constructing and testing full-scale non-nuclear reactor prototypes in Denmark and is currently working with the Paul Scherrer Institute in Switzerland to prepare for the initial nuclear test of the reactor.

Copenhagen Atomics is developing a containerized molten salt reactor. Using unpressurized heavy water as a moderator, this reactor consumes nuclear waste while generating new fuel from thorium. Compact enough for mass production and assembly line techniques, the reactor has a thermal output of 100 MWt. The company's goal is to provide energy at a levelized cost of just EUR20 (USD23.5) per MWh.

The company's thorium reactors are projected to consume transuranic elements found in used nuclear fuel from conventional reactors, significantly decreasing the volume of long-lived radioactive waste. To achieve this, Copenhagen Atomics plans to process used nuclear fuel from light water reactors into four categories: zircaloy, uranium, fission products, and transuranics. Their reactor designs can utilize plutonium (a transuranic) to initiate the use of thorium.