Frequently Asked Questions


What is the Natrium™ reactor?

The Natrium technology has a 345MWe sodium fast reactor coupled with a molten salt-based integrated energy storage system that will provide clean, flexible energy and stability for the grid. The system can boost output to 500MWe for more than five and a half hours to serve peak demand. The reactor maintains its thermal power constant during its entire operating period, maximizing its capacity factor and value. The technology provides dispatchable power at a scale that can make a difference in efforts to decarbonize electricity and stabilize grids with high penetrations of renewables.

What are some of the features of the Natrium technology?

The Natrium technology is an integrated energy system powered by a sodium fast reactor. With energy storage and flexible power production, the technology offers abundant clean energy at a competitive cost. The Natrium technology is the best option for deploying advanced nuclear power in a world with an ever-growing mix of renewable energy sources because it:

  • Simplifies construction and architecture compared to previous reactor types
  • Offers a cost-competitive, flexible technology that supports load following, energy storage and industrial process heat applications
  • Brings step-change improvements in fuel and operational costs
  • Provides a utility-scale decarbonization solution that can make a meaningful impact on efforts to mitigate climate change

How is the Natrium reactor more economical than other reactor technologies?

The Natrium technology has been designed to reduce complexity, cost and construction schedule. The key innovation relative to past reactors is the novel architecture that separates and simplifies major structures. The power block, which represents most of the plant, can be constructed and operated without the need for special nuclear requirements or nuclear regulatory approval.

The compact atmospheric pool reactor system with passive vessel cooling significantly reduces space and the amount of nuclear-grade concrete required. In fact, on a per MWe basis, it uses 80% less nuclear-grade concrete compared to today’s large reactors.

What is the Natrium technology’s integrated energy storage system?

The Natrium technology uses a sodium fast reactor to produce heat, which can be used to generate electricity immediately or be contained in thermal storage reserves for hours. This innovative combination with energy storage allows the reactor to operate at a steady state, supporting the increased use of renewables and helping utilities capture more daily electricity revenue. As more and more renewables are integrated into the grid, the demand for gigawatt-hour-scale energy storage will continue to increase.

Why did you choose to develop a sodium-based technology?

The team chose liquid metal sodium as the reactor coolant because it has several excellent characteristics that include:

  • Operation at atmospheric pressure: Sodium is a high-temperature liquid with a boiling point that is far higher than temperatures experienced during operations. This allows operation at atmospheric pressure, meaning that the reactor can use thinner, easier to fabricate metallic structures. This also avoids the expense of large, pressure-retaining equipment and civil structures.
  • Exceptional heat transfer: Because sodium is a liquid metal, it has exceptional heat transfer. This results in high power density, meaning that large amounts of heat can be generated and harnessed with a small footprint. The main driver for the heat transfer is the coolant’s ability to transfer heat, its thermal conductivity, which is three times higher than stainless steel, the reactor structural material. High power density, combined with the inertia of the sodium pool configuration, leads to a smaller heat supply and heat removal systems. The high heat transfer of the reactor coolant, even under natural circulation, enables direct heat removal from the surface of the vessel by air. Heat removal from the vessel surface is responsible for a major reduction in equipment and structures versus previous nuclear technologies.
  • High Temperature: The high-temperature capability of the sodium drives eight percentage points higher thermal efficiency as compared to conventional light water reactors. It also enables process heat applications for refining and petrochemical processes, chemicals, forest products and other sub-sectors traditionally fueled by natural gas.
  • Practicality: Sodium is a practical coolant that supports longevity and minimal maintenance on components. It has high-temperature capability. It maintains the high energy of the neutrons without degrading. Maintenance of sodium quality is a simple established process. It also doesn’t corrode materials, so operators can avoid corrosion-driven maintenance of permanent reactor structures.
  • Extensive experience: Building on the scientific community’s more than six decades of experience using sodium, this technology can be commercialized quickly enough to make a difference in decarbonization efforts.

Team Behind the Technology

Who are the partners working together to develop and demonstrate the Natrium technology?

TerraPower, GE Hitachi Nuclear Energy and Bechtel submitted a proposal for the Department of Energy’s (DOE) Advanced Reactor Demonstration Program (ARDP). The team behind the Natrium technology combines decades of unparalleled expertise and the technical capabilities necessary to bring this innovative system to market. Both TerraPower and GE Hitachi Nuclear Energy have extensive sodium fast reactor design, analysis, licensing and testing experience spanning decades. For the ARDP proposal, Bechtel adds current and unmatched experience managing and executing large nuclear projects and the team’s utility partners bring operating capabilities alongside a market demand for utility-scale advanced nuclear technologies.


What type of fuel does the Natrium reactor use?

The Natrium reactor uses high-assay, low-enriched uranium (HALEU) metallic fuel. HALEU is a new class of nuclear fuel where the uranium-235 isotope content is above 5% but less than 20%. Many advanced reactors, including the Natrium technology, use HALEU because it improves reactor performance. For example, with HALEU, the reactor size can often be reduced and fuel utilization can be improved.


Are you seeking support through any government funding opportunities?

TerraPower was selected by the U.S. Department of Energy to demonstrate the Natrium technology with GE Hitachi Nuclear Energy. Read the announcement.


What is your timeline for deploying the Natrium technology?

Due to its financing credibility and an achievable funding strategy, the Natrium technology will be available in the late 2020s. This will make it one of the first commercial advanced nuclear technologies. With local leaders and policymakers setting ambitious clean energy targets, the Natrium technology is well-positioned to help push the future energy mix to a cleaner tomorrow.

How long before the first power plant with the Natrium technology is operational?

The Natrium technology will be available in the late 2020s, making it one of the first commercial advanced nuclear technologies.