Tractebel to support Thorizon on molten salt reactor development

Today, the Dutch-French start-up, Thorizon, and the global engineering and consulting company, Tractebel, signed a strategic three-year partnership to advance the Thorizon One molten salt reactor. Tractebel will provide engineering services including support on the conceptual design, computational modelling, cost estimates and design reviews.

  • Tractebel will help Thorizon develop an advanced modular reactor (AMR) based on molten salt, using spent fuel from existing nuclear power plants as an important source of carbon-free energy. Unlike in traditional nuclear reactors, this reactor core contains molten salt which acts as both the fuel and the coolant. The molten salt, given its inherent physical properties, is capable of handling high temperatures and allows low-pressure operation under all circumstances. This type of reactor has the potential to make nuclear power more sustainable, cost-effective and inherently safe.

    The Thorizon One will provide 250MW of industrial heat which can be directly used in industrial processes (e.g., chemical industry or hydrogen production) or can be transformed into electricity for 250.000 households. The molten salt fuel adopted by Thorizon uses a combination of long-lived elements from reprocessed spent fuel and thorium. The reactor will be able to recycle long-lived waste from existing nuclear facilities. What is unique about the Thorizon One concept is that the core is composed of a set of cartridges that is replaced every 5 to 10 years. This concept offers additional advantages in terms of safety, time to market and costs:

    • Safety: The reactor only generates energy when salt is circulated through the cartridges. If the pump stops, the reactor shuts down. This makes the design “walk-away” safe.
    • Time to market: The cartridge design enables the use of existing and proven materials and components, minimizing development and licensing timelines.
    • Costs: Cartridges are efficiently produced in series off-site. They contain all primary systems, together with low-pressure operations, which results in a lean reactor building.

    “For several years, Tractebel has been a frontrunner in the deployment of SMRs, which we believe will contribute to achieving carbon neutrality by 2050. We are now proud to support Thorizon for the development of a Generation IV reactor. This ground-breaking technology will close the fuel cycle and make the circular economy a reality in the nuclear sector. Thanks to its flexibility, this advanced nuclear reactor concept could contribute to addressing both the challenges of industry decarbonisation by providing heat for industrial processes and of energy security by producing electricity for households” says Vincent Schryvers, Business Manager Netherlands, Tractebel.

    “The expertise Tractebel has built while supporting operating nuclear power plants across Europe for decades, and more recently working on multiple small modular and innovative reactor concepts is invaluable for a start-up like ours. The large and experienced team in Belgium is ideally suited to help us make the connection between the Netherlands and France. We very much look forward to working together with the Tractebel team in our offices in Amsterdam and Lyon,” adds Kiki Lauwers, CEO of Thorizon.

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  • About Tractebel

    Tractebel is a global engineering and consulting company delivering integrated solutions for sustainable energy and built environment projects. Our expertise is trusted worldwide across multiple markets like nuclear, renewables, power & gas, electrical grids, hydropower & dams, water resources & supply, desalination, complex & high-tech buildings, transport infrastructures, and ports & waterways.
    By connecting strategy, design, engineering, social & environmental studies, project management and in-house digital applications, we partner with companies and public authorities to create a positive impact on people and the planet.
    Backed by more than 150 years of experience, today Tractebel is a community of over 5,600 passionate experts across the globe, committed to ethical business and the fight against climate change. Tractebel is part of the ENGIE Group, a global reference in low-carbon energy and services.

    About Thorizon

    Thorizon has rapidly evolved from a spin-off of NRG (Dutch Nuclear Research Institute) into an ambitious deep-tech startup, with offices in Amsterdam and Lyon. The company views small modular nuclear reactors as an ideal, stable, and clean contributor to an energy system where wind and solar are the other important sources. The ambition is to develop a reactor based on molten salt that can be realized rapidly and in a smart way, is safer than existing nuclear plants, and takes a first step towards nuclear resource circularity. Thorizon is working to further strengthen its financial position to be able to build a non-nuclear molten salt demonstrator in the short term and finalize the detailed design to start building its first-of-a-kind reactor by 2030: the Thorizon One. For more information about Thorizon, you can visit


    Daphné Charleton, Nuclear Communication Manager, Tractebel + 32 470 83 29 56

    Fione den Outer, Marketing, Thorizon +31 6-24235238