Danish Thorium Molten Salt Reactor receives pre-seed funding

Copenhagen-based Seaborg Technologies, which is developing thorium-based Molten Salt Reactors (MSRs), has received pre-seed investment round. 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.

Seaborg Technologies has received early funding for its thorium molten salt reactor. The CUBE (Compact Used fuel BurnEr) reactor concept has features including:

– unparalleled non-proliferation profile,
– excellent waste-burning abilities using thorium as catalyst,
– ultra-compact form factor, five times smaller than competing MSRs,
– and a fully modularized core optimized for mass production.

The CUBE reactor has a long list of additional benefits including
* exceptional high thermal efficiency
* a wide range of fuel options
* excellent load power following capabilities (compatibility with variable renewables)
* a host of process heat applications.

Their unique use of thorium not only enables waste burning in a thermal spectrum reactor, but also greatly improves the sustainability of nuclear power. The waste salt remaining at the end of the reactor lifetime can be used to fuel new reactors operating directly on a closed thorium fuel cycle – and thus supply carbon-free energy to a rapidly developing global population for centuries to come! The CUBE reactor therefore truly makes nuclear sustainable.

There is a 30 page whitepaper.

Seaborg Technologies propose to initiate further investigation into a more detailed design of such a waste-burning molten salt reactor with the aim of constructing a pilot plant. The high temperature, single salt, thermal-epithermal core, is designed to be highly modular, thus it can be mass produced and decommissioned on assembly line basis. The pilot plant as well as the commercial versions investigated in this report are designed to operate at 50 MWt. However, the neutronics calculations indicate that it would be favorable to
scale up power to 150 MWt or 250 MWt.

A key feature in the present design is the use of thorium in conjunction with the spent nuclear fuel. The thorium fuel cycle produces significantly less of the long-lived and problematic transuranic waste than both a conventional reactor and a fast plutonium breeder reactor. As a consequence, the core produces much less transuranic waste than it consumes; hence, it is a waste-burner. The 50 MWt core reduces the amount of transuranic waste in the world by approximately 1 ton over its 60 years power plant lifetime, while building up 233U concentration in the fuel salt to a level where it could potentially sustain a closed thorium fuel cycle.

The reactor relies on a novel on-board chemical fluoridation flame reactor, which can continually extract fission products from the salt during operation. The flame reactor is also used to adjust the fuel levels in the salt such that no absorbing control rods are needed during normal operations; this facilitates a better neutron economy in the reactor. Though no actinide element in this highly proliferation resistant reactor has weapon quality isotope composition at any point during the reactor lifetime, it is worth noting that the chemical reprocessing system is designed such that plutonium cannot be separated from the significant amount of neptunium present in the reactor. Seaborg Technologies propose building a 50 MWt liquid fuelled molten salt pilot reactor.

The purpose of this is to showcase the viability of the SWaB reactor and to provide valuable insights into corrosion and swelling of the graphite moderator; two of the biggest issues limiting the operational lifetime of this class of reactors.

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.