Seaborg Technologies is a private Danish

startup A startup or start-up is a company or project undertaken by an entrepreneur to seek, develop, and validate a scalable business model. While entrepreneurship includes all new businesses including self-employment and businesses that do not intend to ...

. It is developing small

molten salt reactors A molten-salt reactor (MSR) is a class of nuclear fission reactor in which the primary nuclear reactor coolant and/or the fuel is a mixture of molten salt with a fissile material. Two research MSRs operated in the United States in the mid-20t ...

. Founded in 2015 and based in

Copenhagen Copenhagen ( ) is the capital and most populous city of Denmark, with a population of 1.4 million in the Urban area of Copenhagen, urban area. The city is situated on the islands of Zealand and Amager, separated from Malmö, Sweden, by the ...

, Denmark, Seaborg emerged as a small team of physicists, chemists, and engineers with educational roots at the

Niels Bohr Institute The Niels Bohr Institute () is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics, and biophysics. Overview The institute was foun ...

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Gene ...

, ESS (European Spallation Source) and DTU (Technical University of Denmark) who share a common vision of safe,

sustainable Sustainability is a social goal for people to co-exist on Earth over a long period of time. Definitions of this term are disputed and have varied with literature, context, and time. Sustainability usually has three dimensions (or pillars): env ...

and cheap

nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...

Compact Molten Salt Reactor

The reactor designed by Seaborg Technologies is called the Compact Molten Salt Reactor (CMSR). The company claims that it is inherently safe, significantly smaller, better for the environment, and inexpensive even compared to fossil fuel-based electricity. Conventional nuclear reactors have solid fuel rods that need constant cooling, typically using water under high pressure. Water is abundantly available but its low boiling point is a vulnerability creating a potential point of failure. In contrast, in a CMSR, fuel is mixed in a liquid salt whose boiling point is far above the temperatures produced by the fission products. This enables it to operate stably at a pressure of one atmosphere. Unlike other thermal spectrum molten salt reactors the CMSR was originally planned to not use graphite as a moderator. Instead it would have used molten

Sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula . It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive base (chemistry), ...

(NaOH) contained in pipes adjacent to and interlaced with pipes that contain the molten fuel salt. This enabled a more compact design. It also allowed the liquid moderator to be rapidly removed from the core as a fission control mechanism. In early 2023 however, Seaborg made the decision to switch at least the first generation of developed reactors to Low-Enriched Uranium (LEU), instead of the originally planned High-Assay-Low-Enriched Uranium (HALEU) due to potential issues with HALEU supply, which did not meet their desired timeline for the CMSR. This involved switching the moderator to graphite from NaOH as well. In the case of an overheating accident, a frozen salt plug at the base of the reactor melts and the liquid fuel flows out of the reactor core away from the moderator into cooled tanks where the reaction quenches, the fuel cools and solidifies, without dispersing in the surrounding environment. The approach mitigates the danger of a failure rather than eliminating all failures.

Deployment

The company intends to deploy its

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sized reactors on barges. Reactors are manufactured at scale in a central facility, reducing costs. Using barges makes them mobile. Single reactor output is estimated to be 100 MWe. Multiple units could be deployed on a single barge. The primary design challenge is in preventing the highly corrosive fuel slurry and moderator from damaging the reactor. The fueling cycle is 12 years. It offers no proliferation risk or military applications. Seaborg Technologies hopes to deliver the first power barge in 2028.

References

{{Reflist Nuclear reactors Technology companies based in Copenhagen Danish companies established in 2015 Companies based in Copenhagen Municipality