Europe’s first large scale pilot for thorium molten salt reactors underway

It brings together Danish molten salt reactor developer Copenhagen Atomics and the Paul Scherrer Institute PSI, Switzerland’s largest research institute for natural and engineering sciences.

The four year project will validate, design, construction, license, operate and decommission the technology, compiling data for commercial deployment, and provide open-source data for reactor modelling tools.

“We’re very excited to work on advancing molten salt reactor technology together with PSI, who come with world-class expertise, experience, and facilities to conduct large-scale nuclear experimental work,” said Aslak Stubsgaard, CTO of Copenhagen Atomics. 

“Personally, I am very glad that Copenhagen Atomics has decided to work with PSI as a collaboration partner to prove the feasibility of their vision here at our institute,” said Marco Streit, Head of PSI Hot Laboratory

Molten salt reactor technology is still largely experimental, employing molten salt as the main coolant source, as well as a fuel carrier. Thorium variants employ that chemical element as their primary fuel in place of uranium; although uranium is more commonly used in nuclear operations, thorium is estimated to be three times more abundant in the Earth’s crust.

While still experimental, thorium molten salt reactors (TMSRs) offer the potential for efficiency, safety and  waste reduction.

The use of salt permits high boiling points but low pressures as well as chemical stability. TMSRs are also less amenable to being adapted for weapons.

Pic: Copenhagen Atomics’ Onion CoreTM will carry out critical experimentation in collaboration with PSI’s Hotlab in 2026