TerraPower secures Hyundai partners to scale Natrium reactor production

TerraPower pushed Natrium further from design work and into industrial reality on May 20, signing new agreements with HD Hyundai and Hyundai Engineering & Construction in New York City. The most important piece was a supply framework that names HD Hyundai Heavy Industries as a preferred manufacturer for Natrium reactor enclosure system components, a move TerraPower says is meant to create a scalable supply chain for serial production rather than a one-off build.

That matters because Natrium is no longer just a concept on paper. TerraPower is building its first plant near the retiring Naughton coal plant in Kemmerer, Wyoming, and the project already carries major federal backing. The U.S. Department of Energy has described the unit as a single-unit, 345 MWe net plant, while the company says the integrated molten-salt energy storage system can lift output to 500 megawatts when the grid needs it. In a market that increasingly rewards flexible generation, that storage package is part of the commercial pitch, not just the engineering story.

The Korean agreements extend a procurement strategy TerraPower has been building for years. In December 2024, the company awarded the first Natrium plant’s reactor enclosure system contracts to Spain’s ENSA and South Korea’s Doosan Enerbility, with ENSA set to produce the reactor head and Doosan supplying the core barrel, guard vessel and internal supports. The new HD Hyundai Heavy Industries framework follows a year-long joint study, signaling that TerraPower is trying to lock in repeatable manufacturing capacity well before the first unit goes into service.

The timing also matters. The U.S. Nuclear Regulatory Commission authorized issuance of the Kemmerer Unit 1 construction permit in March 2026, and TerraPower announced the official start of construction on April 23. TerraPower has said construction staffing could peak at about 1,600 workers, with roughly 250 full-time staff expected once the plant is operating. The DOE’s Advanced Reactor Demonstration Program has authorized up to $2 billion for the project under a 50-50 cost share, keeping the first Natrium unit tied closely to federal demonstration goals even as TerraPower and its partners try to make the supply chain look more like an industrial program than a prototype effort.

That is the real significance of the Hyundai deal. Natrium’s next hurdle is not just licensing or excavation at Kemmerer, but whether TerraPower can keep standardizing parts, widening its vendor base and proving that advanced reactors can be manufactured in sequence.