TerraPower President and CEO Chris Levesque has announced that the company’s Natrium reactor has been accepted into the UK’s Generic Design Assessment (GDA) process. “TerraPower prides itself on its technical rigor, and we will bring our industry-leading team and robust regulatory experience to support this review,” he said. “We look forward to working with the Department for Energy Security and Net Zero (DESNZ), Office for Nuclear Regulation (ONR), and Environment Agency (EA) in the coming months, and ultimately advancing our efforts to bring a Natrium reactor to the UK.”
TerraPower submitted the GDA application in October 2025. DESNZ made the request to UK regulators following its readiness review of the TerraPower’s application. The review concluded that the design is ready to enter the GDA process. The ONR said: “The assessment will begin once the necessary arrangements around timescales and resources have been put in place.”
The Natrium technology features a 345 MWe sodium-cooled fast reactor with a molten salt-based energy storage system. The storage technology can boost the system’s output to 500 MWe of power when needed as it is designed to keep base output steady, ensuring constant reliability and can quickly ramp up when demand peaks.
With respect to small modular reactors (SMRs), Rolls-Royce SMR Limited’s SMR design entered the GDA process in 2022 and is currently in Step 3 – the final step – of the process; Holtec’s SMR-300 entered the GDA process in December 2023 and is currently in Step 2; and GE Vernova Hitachi’s BWRX-300 entered the process in January 2024 and completed Step 2 in December 2025.
TerraPower began non-nuclear construction for its first Natrium plant, in Kemmerer, Wyoming, in June 2024, and expects construction of the plant to be complete in 2030. The first Natrium project is being developed through the US Department of Energy’s (DOE’s) Advanced Reactor Demonstration Program (ADRP).
In January, social media giant Meta announced plans which included funding to support the development in the US of up to eight Natrium sodium fast, plus the rights for energy from up to six other Natrium units capable of producing 2.1 GWe and targeted for delivery by 2035.
