US-based TerraPower has received notification from the US Nuclear Regulatory Commission (NRC) that they have successfully completed the Environmental Impact Statement (EIS) for the Natrium project being developed in Wyoming and found no adverse impact to the environment. This is the first advanced reactor plant to achieve this regulatory milestone.
“TerraPower has been committed to bringing the next generation of nuclear power to fruition, and this announcement from the NRC is a testament to our team’s dedication and rigor in meeting all federal licensing requirements,” said TerraPower President & CEO Chris Levesque.
The next step for the construction permit application (CPA) is the final safety evaluation, which is anticipated by 31 December. TerraPower was the first developer to submit a CPA for a commercial advanced reactor to the NRC in March 2024. President Trump’s Executive Orders signed in May 2025 supported the streamlining of regulatory reviews.
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. Terrapower says the decoupled design separates major structures into two independent islands – nuclear and energy, which significantly reduces the quantity of specialised materials, cutting plant costs and accelerating construction timelines.
TerraPower broke ground on the Natrium project in 2024 at its site in Kemmerer in Wyoming and immediately began construction efforts for the non-nuclear parts of the plant. The Natrium design features a 345 MWe sodium-cooled fast reactor with a patented 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.
TerraPower is building its first plant through a public-private partnership with the Department of Energy’s (DOE) Advanced Reactor Demonstration Program (ARDP). This authorises a 50/50 cost share and up to $2bn for the Natrium project. TerraPower and partners will match this investment dollar for dollar. The ARDP was awarded under President Trump’s first administration. Continued federal support for deploying new plants was outlined in President Trump’s May Executive Orders.
The first-of-a-kind cost for the Natrium demonstration plant will include the reactor design and licensing, codes and methods development, fuel development and qualification, and the design, construction and operation of two supporting facilities: the Natrium Fuel Fabrication Facility and Sodium Test and Fill Facility. The sodium facility will be used to test and demonstrate the performance of first-of-a-kind equipment prior to operations in the reactor plant. According to Terrapower, the project is expected to be completed in 2030.
However, while the TerraPower website provides some details of work done with molten salt, it contains very little information about the fast reactor technology. It is also notable that none of the contracts signed with suppliers relate to the reactor itself. Currently, the only commercially operating sodium-cooled fast reactors are in Russia. Development of these reactors took decades with full government support. In the US and Europe research on fast reactors took place in the 1960s and 1970s but all the projects have been closed down.
