Nuclear waste has the potential to supply power to Europe for many years. This startup aims to demonstrate its feasibility.

      Europe has been converting uranium into energy for more than fifty years, resulting in the accumulation of extensive nuclear waste. This radioactive material may take millions of years to become safe, and there is still uncertainty about how to manage it.

      Thorizon, a startup from France and the Netherlands, has proposed a solution: repurposing nuclear waste to generate new energy. The company is working on a small modular molten salt reactor (MSR) that utilizes a combination of spent nuclear fuel and thorium, a radioactive metal with significant potential.

      Thorizon plans to start building its first reactor, Thorizon One, in the next five years. When operational, the facility is projected to generate 100 megawatts of electricity, sufficient to power around 100,000 homes or a large data center.

      “We're not merely constructing a new reactor — we’re reevaluating our approach to the fuel we already possess,” stated Thorizon’s CEO Kiki Leuwers in an interview with TNW. “Europe has a valuable stockpile of nuclear material. With the appropriate technology, that waste can become a resource.”

      A 3D rendering of Thorizon’s nuclear reactor: Credit: Thorizon

      When uranium is used as fuel in a nuclear reactor, its atoms undergo fission, releasing heat. This heat is then converted into steam, which drives a turbine to produce electricity. The radioactive waste generated still contains about 90% of the original energy from the uranium.

      Leuwers estimates that the nuclear waste stored in Europe could supply the entire region with power for 40 years. In the US, scientists estimate it could provide energy for approximately 100 years.

      Why has nuclear waste not been reused?

      Countries such as the US, France, and Japan have recognized the potential of recycling spent nuclear fuel for years. In the 1960s and 70s, many advanced fast reactors were created to extract more energy from nuclear fuel and even "breed" new fuel from waste. However, most of these reactors were decommissioned in the following decades.

      The main reasons for this were political and economic. Fast reactors produce large amounts of plutonium, a key ingredient in nuclear weapons. During the peak of the Cold War, concerns about nuclear proliferation led many nations, particularly the US, to halt nuclear waste recycling efforts.

      At the same time, a global abundance of uranium was discovered. New deposits found in Australia, Canada, and Africa caused prices to drop, making it cheaper to mine fresh uranium instead of investing in recycling infrastructure. These factors combined to stall radioactive recycling initiatives.

      While France and Japan still process some of their used fuel, most of the world’s nuclear waste is currently stored in large steel cylinders known as dry casks, which serve as a temporary solution to a very long-term issue. Efforts to dispose of it deep underground—such as Finland’s Onkalo repository, which is located 500 meters deep—are advancing but remain controversial and costly.

      The expansion of nuclear power in Europe continues to be a complex issue; however, the situation may be changing. Confronted with the dual challenges of climate change and energy insecurity, countries like the UK and France are advocating for increased nuclear power capacity, particularly through small modular reactors (SMRs).

      Regardless of whether nuclear energy regains its momentum, Europe still faces a significant nuclear waste challenge, one that Thorizon seeks to address.

      How will Thorizon’s plant function?

      Thorizon’s MSR operates under high temperatures and low pressure, enhancing safety and efficiency. Should an issue arise, the salt solidifies, containing the radioactive material and reducing the likelihood of leaks or explosions.

      MSRs were initially created in the 1960s at the Oak Ridge National Laboratory in the US, showing great promise. However, they never achieved commercial success, primarily due to the technical difficulties and costs associated with safely containing the corrosive salts.

      To address this, Thorizon’s design incorporates a cartridge system. Each large steel cylinder is filled with molten salt combined with a mix of spent fuel from conventional reactors and fresh thorium—a radioactive material that is more plentiful than uranium and easier to handle. The concept is to replace these cylinders once the radioactive portion of the fuel has been largely depleted.

      “The cartridge approach allows us to contain the most extreme conditions within the reactor,” stated Leuwers. “It is modular, replaceable, and provides a safe method for managing radioactive materials.”

      Thorizon was established in 2018 as a spinoff of the Netherlands’ nuclear research institute NRG. The company currently employs about 50 engineers based in Amsterdam and Lyon. Thorizon claims it has finalized its conceptual design and is engaged in regulatory discussions with authorities in the Netherlands, France, and Belgium.

      Three pre-feasibility studies are currently being conducted for potential launch sites in France, the Netherlands, and Belgium. Industry collaborators, including the Dutch manufacturing giant VDL, are assisting in prototyping core components.

      By merging spent uranium fuel with thorium in a molten