US-based TerraPower has received approval from the Wyoming Industrial Siting Council (ISC) on its permit to construct a Natrium demonstration plant near a retiring coal-fired plant at Kemmerer. The permit covers all construction and operational activities on the plant that are not under the jurisdiction of the US Nuclear Regulatory Commission (NRC). ISC reviews the socio-economic and environmental impacts of industrial facilities before issuing a permit for construction. Emphasis is placed upon social-economic impacts.
Terrapower’s Natrium technology features a 345 MWe sodium-cooled fast reactor using high-assay low-enriched uranium (HALEU) fuel, with a molten salt-based energy storage system that can boost the system’s output to 500 MWe for more than five and a half hours when needed.
The ISC permit, which TerraPower applied for in October 2024 – will allow for the construction of non-nuclear facilities of the plant, including the energy island portion of the Natrium plant that houses the molten-salt energy storage tanks and turbines. With this permit complete, TerraPower will continue its construction schedule, with plans to start construction on both the Kemmerer Training Centre and the energy island in 2025, as well as continue work on the sodium test and fill facility that began in 2024.
“This is the first state permit ever awarded to a commercial-scale advanced nuclear project and is a testament to the groundbreaking work of our TerraPower team,” the company’s President and CEO Chris Levesque said. “The regulatory process to bring new nuclear plants to fruition is robust, and our team has been working relentlessly to successfully manoeuvre through a complicated, multi-jurisdictional environment to bring the first Natrium plant to market.”
TerraPower noted that it is the only advanced nuclear developer with a permit application for a commercial advanced reactor submitted to NRC, which oversees the nuclear portions of the Natrium plant. Terrapower says the application, submitted in March 2024, is expected to be approved in December 2026. “The unique Natrium design enables the company to start non-nuclear construction onsite during the NRC review,” TerraPower said.
A ground-breaking ceremony held in June 2024 marked the start of non-nuclear construction at the Kemmerer site, and came weeks after the NRC accepted for docketing TerraPower’s application for a construction permit, submitted earlier in 2024.
In its application to the ISC, TerraPower said: “Contingent upon obtaining approval from the ISC and securing all other required permits, building activities are planned to begin in March 2025 and continue for approximately 69 months. Nuclear fuel load is projected for fall of 2030 and commercial operation for the fall of 2031.”
However, TerraPower will need to submit a separate operating licence application to obtain permission to run the reactor, for which it has provided very few technical details. While the TerraPower website provides some details of work done with molten salt, it contains very little information about the reactor technology.
According to a video: “In the reactor building, advanced uranium fuel is inserted into an enclosed container and covered with liquid sodium. A chain reaction starts when uranium atoms slit and release neutrons and heat the metal coolant inside the reactor system…. The liquid sodium is heated and then transfers thermal energy to pipes filled with molten salt. This… then travels to a very large storage tank that serves as a thermal battery for the plant…. The molten salt passes near water-filled tubes and boils the water to make super heated steam. This… then helps to turn a turbine, creating electricity…. The molten salt is transferred to a cold tank and eventually back to the nuclear island.”
Basically, the Natrium reactor is a sodium-cooled fast reactor. Currently, the only commercially operating liquid metal-cooled fast reactors are in Russia, using sodium as the coolant. While research on sodium-cooled fast reactors took place in the 1960s and 1970s in the US and Europe, interest waned following the 1979 Three Mile Island accident in the USA and the Chernobyl disaster in 1986. By the early 1990s the US, the UK and Germany had closed down their programmes. France continued with its projects for a few more years, until 2009, Subsequently, in 2019, France also cancelled its Generation IV ASTRID sodium-cooled fast reactor demonstrator design project. Although interest is now reviving in Europe and the USA both through collaborative projects and government support for private company initiatives, it remains at the early design phase and is probably decades away from implementation.
