Seaborg Technologies secure funding for thorium-based molten salt reactors

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A Danish company is aiming to build smaller, safe nuclear reactors based on thorium and molten salt, after securing funding in its first pre-seed investment round.

molten salt
Seaborg reactor with a human for scale

Copenhagen-based Seaborg Technologies, which is developing thorium-based Molten Salt Reactors (MSRs), has received funding from an investment coalition led by Danish innovation incubator PreSeed Ventures.

The company hopes the funding will accelerate development of its CUBE (Compact Used fuel BurnEr) reactor concept.

The compact, modular CUBE reactor, which can fit inside a 20-foot container, could provide enough power for 200,000 homes, the company claims.

Unlike conventional nuclear reactors, which are based on solid pellets or rods of low-enriched uranium, MSRs use a liquid fuel – molten salt.

In a conventional reactor the solid uranium pellets must be submerged in water to keep them cool. If this cooling water is lost, the reactor melts down.

In contrast, in an MSR the molten salt acts as both the fuel and the coolant, meaning that if the reactor loses its coolant it also loses its fuel, and the reactor stops automatically, according to Troels Schönfeldt, CEO of Seaborg Technologies.

“Molten salt reactors cannot melt down, or suddenly explode, and their safety is based on physics instead of engineering,” he said. “That means you don’t need a lot of engineering solutions to ensure safety, which in turn saves you a lot of money.”

As a further passive safety measure, if any residual heat produced once the reactor has shut down causes the core to reach a threshold temperature, it causes a plug of frozen salt to melt at the bottom of the core. This drains the warm salt to a dump tank where it cools down by itself.

By using thorium as a catalyst, the reactor is able to burn nuclear waste from conventional reactors, meaning it could help to reduce the problem of radioactive waste storage.

“We take waste from existing nuclear power plants and we burn the transuranic elements of it, the longest-lasting part of the waste,” said Schönfeldt.

What’s more, while conventional nuclear reactors must operate at very high pressures, MSR reactors operate at just one bar atmospheric pressure, making them simpler to construct.

The new investment will allow Seaborg’s team to increase its staff to 16 employees, making it the largest reactor development start-up in Europe.

“We don’t want [the technology] to be useable for nuclear weapons, so we are putting a lot of science and effort into making that impossible,” said Schönfeldt.

molten salt
Troels Schönfeldt (seated) with colleagues Andreas Vigand Pedersen & Eirik Eide Pettersen

The company will begin carrying out initial, small-scale experiments within the next few months.

Seaborg has previously received funding from the EU and the Danish Innovation Fund, and will be looking to raise an additional €2m from investors as soon as possible.

As well as accelerating its own technology development, the company hopes the investment will also help speed up the road to market for all MSR developers.

In particular, existing regulatory systems act as a barrier for thorium-based MSRs, said Schönfeldt.

Simulation of an MSR must include modelling the interdependence between neutron transport, fluid dynamics, heat transfer, and the associated chemical reprocessing, he said. Existing tools are either not compatible with the current regulatory requirements, or not able to include these effects, he said.

“This represents an important barrier to the deployment of MSRs.”

The investment will allow the company to develop advanced simulation software that can be used by all developers and regulators within the licensing process, said Schönfeldt.

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