US-based TerraPower has signed strategic agreements with South Korean companies HD Hyundai and Hyundai Engineering & Construction (HDEC) to accelerate the commercial rollout of Natrium sodium‑cooled fast reactor plants, including their integrated energy storage systems, in the coming years. This is seen as a key step toward serial production and fleet‑scale deployment of the technology.
TerraPower and HD Hyundai signed a supply framework agreement that establishes HD Hyundai Heavy Industries (HHI), a shipbuilding subsidiary of HD Hyundai, as a preferred manufacturer for Natrium Reactor Enclosure System (RES) components, securing a scalable supply chain for serial production of Natrium reactors. HHI was selected as the strategic manufacturing partner following a thorough review of its fabrication capabilities, large-scale industrial production expertise and proven track record in precision manufacturing for the energy sector.
In a separate agreement, TerraPower, HD Hyundai and HDEC outlined a strategy to leverage HD Hyundai and HDEC’s expertise in project delivery and execution excellence to support TerraPower’s commercialisation plans. The three companies plan to collaborate on the design, manufacturing, supply chain, construction, commercial structure and delivery of multiple units of TerraPower’s Natrium technology. TerraPower said this collaboration will be vital to shaping fleet deployment and the financing of Natrium reactors.
“Collaborating with HD Hyundai and Hyundai Engineering & Construction represents a powerful alignment of global innovation, manufacturing excellence and world‑class project delivery,” said Chris Levesque, president and CEO of TerraPower. “By combining our strengths, we are creating a new era of energy infrastructure—one where advanced reactors like Natrium are unleashed at scale to meet growing demand, strengthen supply chains, and deliver reliable, resilient, affordable power.”
Kwang-shik Won, HHI Senior Executive Vice President & COO noted: “This Framework Agreement not only strengthens our strategic collaboration with TerraPower but also serves as a critical foundation for our entry into the global nuclear market. Through our agreement, we will strive to ensure the timely supply of Natrium reactor equipment and establish a serial production base to secure a formidable global competitive edge.”
HDEC Executive Vice President & COO Young Choi said the collaboration represents a powerful union of vision and expertise. “HDEC is proud to join forces with TerraPower to accelerate the deployment of advanced nuclear reactors. Through this agreement, we aim to lead the energy transition and deliver reliable, carbon-free power on a global scale. Together, we are setting a new standard for the industry and reinforcing our leadership in the new energy strategy.”
In April, TerraPower announced the start of construction of its Natrium plant, Kemmerer unit 1 in Wyoming after the Nuclear Regulatory Commission (NRC) granted the first-ever construction permit for a commercial-scale advanced NPP in March.
The plant features a 345 MWe sodium-cooled fast reactor integrated with a molten salt-based energy storage system. The storage technology allows the facility to temporarily boost its power output to 500 MWe for over five hours, enabling it to follow daily electricity load changes and integrate with renewable energy sources. Construction is expected to involve approximately 1,600 workers, with 250 full-time staff required for operations.
Completion is targeted for 2030. The total project cost is estimated at $4bn, with the Department of Energy (DOE) providing half through its Advanced Reactor Demonstration Program (ARDP). The project has been under active development since TerraPower broke ground on the greenfield site in June 2024 and began construction on non-nuclear support facilities.
