TerraPower begins reactor design approval process in the UK

US company TerraPower has formally notified UK regulators of its intention to begin the Generic Design Assessment (GDA) process for its Natrium sodium-cooled fast reactor. This marks the first milestone on the path to the international deployment of this advanced nuclear technology.

TerraPower submitted an application to the UK Department for Energy Security and Net Zero (DESNZ), officially declaring its intention to enter the GDA process. The process allows the UK Office for Nuclear Regulation (ONR) and the Environment Agency to assess the designs of new nuclear power plants at an early stage.

The aim is to identify and address any potential technical or design shortcomings early, before a specific site is selected and permit applications are submitted. The three-stage process takes approximately four years.

Natrium technology and its potential

The Natrium reactor, developed by TerraPower in collaboration with GE Hitachi, is a 345 MWe sodium-cooled fast reactor. The system also includes molten salt-based energy storage, which allows output to be temporarily increased to as much as 500 MWe for more than 5.5 hours. This flexibility can enable the reactor to be effectively integrated into grids with renewable energy sources.

TerraPower is already building the first project using this technology in Wyoming, USA. The company said it would use experience and the results of the approval process for that project as the basis for its UK GDA application.

TerraPower CEO Chris Levesque said the company had been in discussions with UK partners for several years. He said there was “tremendous interest and opportunity” for US-UK collaboration on the deployment of advanced nuclear technologies over the coming decade.

Ongoing and completed GDAs in the UK

Reactor designs that have successfully completed the GDA process in the past include EDF/Areva’s UK EPR, Westinghouse’s AP1000, Hitachi-GE’s UK ABWR and CGN/EDF/GNI’s UK HPR1000. Currently undergoing GDA are small modular reactors (SMRs) from Rolls-Royce, GE Hitachi (BWRX-300) and Holtec (SMR-300), among others. In 2024, Westinghouse’s AP300 SMR and the LFR-AS-200 lead-cooled fast reactor design from French company Newcleo also entered the process.

TerraPower’s intention to enter the UK market through the GDA process marks a significant step towards the international adoption of advanced next-generation nuclear reactors. Thanks to its flexibility and ability to integrate with renewable energy sources, Natrium technology could play an important role in decarbonising the energy sector in the UK and around the world.