Netherlands-based start-up startup Thorizon, has secured €20m ($16.8m) in funding to accelerate the development of its advanced small modular reactor (SMR) Thorizon One. Thorizon, originally a spin-off from the Nuclear Research & Consultancy Group (NRG), is developing a 100 MWe molten salt reactor. The Thorizon One, described as “walk-away safe”, uses long-lived nuclear waste as fuel. In March 2024, Thorizon and Stellaria working in a consortium with Orano, were selected as winners of the call for projects to develop molten salt reactors under France’s 2030 Innovative Reactor Programme.
The funding includes €16m as the first tranche of its Series A round, led by the Dutch National Promotional Institution, Invest-NL. It is backed by an InvestEU guarantee from the European Commission for the research part, with strong backing from Positron Ventures, PDENH, and Impuls Zeeland. All Thorizon’s existing shareholders reaffirmed their commitment in this investment round.
Thorizon recently secured an additional €4m grant from the Dutch Province of Noord-Brabant in consortium with VDL Groep and Demcon. The recent investments follow an earlier €1m grant in 2024 from the France 2030 Innovative Reactor Programme. In total, including its first equity round, Thorizon has raised €42.5m to support commercialisation of its reactor technology.
This funding brings Thorizon halfway to its Series A target, with a focus on attracting European investors. The capital will drive the prototyping and demonstration of Thorizon One’s “cartridge” fuel system, designed to safely and cost-effectively generate power by recycling nuclear waste. Thorizon will also finalise the reactor’s basic design, advance licensing, and prototype key components with the aim of starting construction in 2030.
“With strong support from our investors and government partners, we are in a solid position to advance the development of Thorizon One,” said Thorizon CEO Kiki Lauwers. “Our mission is to drive nuclear innovation in Europe—enhancing energy security while reducing carbon emissions and burning long-lived nuclear waste. We welcome new strategic partners to join us in making Europe’s first molten salt reactor a reality.”
“We are excited to support Thorizon as it enters the next phase, building and testing the first non-nuclear cartridges for its modular molten salt reactor,” said Reda Atibi, Senior Investment Manager at Invest-NL. “Since our initial investment in 2022, the team has grown, strengthened its expertise, and made significant technological strides.”
Thorizon has laid a strong foundation, securing funding through equity and grants while building a team of 50 engineers across Amsterdam and Lyon. It has forged key partnerships with Orano for fuel development, Tractebel for engineering, and VDL Groep for prototyping, while collaborating with EPZ for early operator input, and with EDF on R&D. Dutch and French nuclear regulators have initiated a joint preparatory review of the Thorizon One design, and the company is conducting pre-feasibility studies at three nuclear-designated sites in France and the Benelux.
Molten Salt Reactors (MSRs) are nuclear fission reactors in which either the fuel and/or the coolant is a molten salt. Molten salt is salt which liquifies at elevated temperatures and can store massive amounts of thermal energy at atmospheric pressure. When used as fuel the molten salt is dissolved with fissile material such as uranium-235, plutonium-239 or uranium-233 that may be mixed with other fissionable material such as uranium-238.
However, if salt is used as a primary coolant rather than water, it can absorb huge amounts of heat at atmospheric pressure, enabling reactors using this technology to operate at very high temperatures. This could in turn enable the production of high-grade heat, opening up the possibility of decarbonizing industrial processes such as producing hydrogen for green steel without the large amounts of greenhouse gases (GHG) currently emitted when producing hydrogen with fossil fuels.
In addition, MSRs in general have passive safety features. For example, if a reactor in an MSR overheats, the liquid salt expands and naturally increases the leakage of neutrons from the reactor core, meaning they are no longer available to cause fission.
According to the International Atomic Energy Agency, (IAEA) several MSR designs are currently under development. While many new designs follow similar principles to the reactors developed in the Molten Salt Reactor Experiment at the US Oak Ridge National Laboratory in the 1960s, there are also many new ideas being researched. These include different fuel cycles, different fuel salts and modular designs – which would make it possible for systems and components to be factory-assembled and transported as a unit to a location for installation.
In Canada, Terrestrial Energy’s integral molten salt reactor (IMSR) concept passed a pre-licensing vendor design review in 2023 – the first such review completed for an MSR. Other projects in China, Russia and the US, continue to make progress.
However, IAEA noted that many key challenges for MSRs remain to be resolved. Standards for design safety and fuel salt transportation have not been developed and the supply chain for MSR-specific reactor components needs to be developed. Analyses of potential accident scenarios unique to MSRs are generally not well known and more experiments and safety demonstration tests remain to be conducted. The fuel-salt chemistry changes with burnup and the retention of radionuclides in normal and accident conditions also need to be studied further.
