HWNEWS
Natrium, TerraPower's sodium cooled small modular reactor (SMR) design, is the first advanced reactor to clear a U.S. construction permit in a decade.
TerraPower's Wyoming reactor didn't go commercial in March. The Nuclear Regulatory Commission cleared a construction permit, a narrower step that, for the first time in a decade, puts the small modular reactor (SMR) category on a credible path for AI-era power buyers. SK Innovation and Korea Hydro & Nuclear Power (KHNP) are already treating it as a beachhead for Korean nuclear exports.
The permit lets TerraPower break ground on its Natrium plant in Kemmerer, Wyoming: the first commercial SMR construction permit the agency has issued since the early 2010s, and the first ever for a non-light-water design. SMRs are compact nuclear reactors designed to be factory-built in modules and shipped to site, rather than assembled custom on location. The Natrium unit is rated at 345 MWe, with an integrated gigawatt-scale thermal storage system that can push output to 500 MWe or more when the grid needs it. The coolant is sodium, which boils at roughly 880°C and lets the reactor run at atmospheric pressure, a meaningful contrast with the 150-bar-plus pressure vessels used in today's light-water reactors. Higher temperatures also open the door to industrial heat uses beyond electricity.
The mechanical case is real, but the regulatory stack is taller than a single permit. Construction authorization does not cover fuel loading, power ascension, or electricity sales. Natrium still needs an operating license, a fuel supply secured at scale (the HALEU, or high-assay low-enriched uranium, supply chain remains constrained), a spent-fuel policy, and a price that survives the next gas-cycle downturn. None of that is settled.
SK Group is positioning itself to be the non-U.S. pole of the Natrium supply chain, and the permit is the event that makes that pitch concrete. SK Inc. and SK Innovation jointly invested $250 million in TerraPower in August 2022, becoming its second-largest shareholder at roughly 10%. KHNP, Korea's state-run nuclear operator, followed with an investment of about $40 million in early 2026, per industry sources. The three parties signed a development and commercialization memorandum in March 2023 that now has a tangible U.S. milestone to point at.
That is the move the article needs to name: Wyoming is a Korean-export beachhead, not a one-off American project. SK's internal market sizing puts the global SMR opportunity at "hundreds of billions of dollars by 2040," a number that is company projection, not independent market estimate. Independent sizing from the IEA, IAEA, and Wood Mackenzie has not been pulled into this draft, and the gap is worth flagging rather than papering over.
The diplomatic choreography backs the industrial read. SK Chairman Chey Tae-won and Bill Gates met in Seoul alongside TerraPower chief executive Chris Levesque and SK Innovation Energy Solutions head Kim Moohwan, then briefed Minister of Trade, Industry and Energy Kim Jeong-gwan on a Korea-U.S. SMR ecosystem. The ask on the Korean side, on the record, is incentives, regulatory modernization, and government-level global partnerships to capture lead position. The ask is unfulfilled, and the gap between the ask and the policy answer is one of the things worth watching.
The cost-overrun record is the obvious counterweight. Olkiluoto 3 in Finland and Vogtle Units 3 and 4 in Georgia both came in years late and billions over budget. The SMR-skeptic case is that 345 MWe units built N at a time have not yet demonstrated a learning curve that beats gas peakers plus renewables for hyperscalers, and that HALEU supply plus spent fuel sit unresolved. None of that has killed Natrium. It has only delayed the question of whether the design can clear the price test once a build cost is on the books.
Wyoming demonstration operation is targeted for 2030, which sets the natural next milestone. The construction permit is the first of several gates; fuel, an operating license, and a price contract will be the rest. SK Innovation's job between now and then is to convert the Korean government's listening posture into a procurement, financing, and export-credit framework that lets Korean suppliers take a defined slice of the Natrium build, and any subsequent Natrium-class plants that follow. The NRC cleared the gate. The harder gates sit on the Korean side of the table.