TerraPower and Natrium: From Bill Gates' Vision to Construction
TerraPower was founded in 2008 by Bill Gates and Nathan Myhrvold with a radical idea: a reactor that could run on depleted uranium for decades without refueling. That original Traveling Wave Reactor never got built — a U.S. ban on nuclear cooperation with China killed the prototype partnership with CNNC in 2018. TerraPower pivoted. The result is Natrium, a 345 MWe sodium-cooled fast reactor with integrated molten salt energy storage, developed in partnership with GE Hitachi Nuclear Energy. In 2020, the DOE selected Natrium for the Advanced Reactor Demonstration Program with up to $2 billion in federal cost-share funding. The site: a retiring coal plant in Kemmerer, Wyoming. Russia's invasion of Ukraine disrupted the HALEU fuel supply and pushed the timeline from 2028 to 2030. But domestic HALEU production has begun at Centrus Energy's Piketon, Ohio facility, and Meta's 2+ GW nuclear commitment has positioned Natrium as a leading technology for data center power. In March 2026, the NRC issued the construction permit for Natrium — the first CP ever issued for a commercial non-light-water reactor — and TerraPower has raised over $1 billion in total funding.
THE COMPLETE TERRAPOWER TIMELINE
Founded in Bellevue, Washington with a vision to develop the Traveling Wave Reactor (TWR) — a sodium-cooled fast reactor designed to run on depleted uranium and operate for decades without refueling. Intellectual Ventures incubation.
TerraPower signed a partnership with China National Nuclear Corporation (CNNC) to build a TWR prototype in China. The agreement represented the fastest path to a demonstration reactor, leveraging China's faster nuclear regulatory and construction timelines.
The Trump administration restricted nuclear technology transfers to China, effectively killing TerraPower's TWR prototype partnership with CNNC. Years of development and the company's primary path to demonstration were eliminated overnight by geopolitical policy.
TerraPower redesigned its strategy around Natrium, a 345 MWe sodium-cooled fast reactor with integrated molten salt energy storage capable of boosting output to 500 MWe at peak demand. Partnered with GE Hitachi Nuclear Energy (GEH) to co-develop the design. A fundamentally different reactor than the TWR.
The U.S. Department of Energy selected TerraPower's Natrium for the Advanced Reactor Demonstration Program (ARDP), providing up to $2 billion in federal cost-share funding. One of only two projects selected (the other: X-energy's Xe-100). The largest federal commitment to advanced nuclear in a generation.
TerraPower selected the site of the retiring Naughton coal plant in Kemmerer, Wyoming for the Natrium demonstration reactor. The coal-to-nuclear conversion leverages existing transmission infrastructure, workforce, and community support. Bill Gates visited the site for the announcement.
Russia's invasion of Ukraine disrupted the global supply of HALEU fuel, which Natrium requires. Russia had been the sole commercial supplier of HALEU. TerraPower announced a two-year delay, pushing the projected online date from 2028 to 2030. The delay highlighted the critical vulnerability of advanced reactor fuel supply chains.
Centrus Energy began producing HALEU at its American Centrifuge Plant in Piketon, Ohio — the first domestic production of HALEU in the United States. While initial quantities were small, this milestone began de-risking the fuel supply chain that had delayed Natrium and other advanced reactors.
TerraPower submitted its construction permit application (CPA) to the Nuclear Regulatory Commission for the Natrium demonstration plant. This initiated the formal NRC review process. Site preparation activities at Kemmerer continued in parallel under NRC allowances for non-safety-related work.
Meta (Facebook) announced a deal to secure 2+ GW of new nuclear energy capacity, with TerraPower's Natrium positioned as a key technology for meeting data center power demands. The tech hyperscaler backing validated TerraPower's commercial model and provided a deep-pocketed anchor customer for future Natrium deployments beyond the Kemmerer demonstration.
On March 4, 2026, the NRC issued the construction permit for the Natrium demonstration plant in Kemmerer, Wyoming — the first construction permit ever issued for a commercial non-light-water reactor in the United States. This historic milestone clears TerraPower to begin nuclear construction. Total funding raised exceeds $1 billion including DOE ARDP cost share. Projected online date remains 2030.
LESSONS LEARNED: WHY TERRAPOWER SURVIVED
TerraPower's journey is defined by adaptation. Unlike NuScale, which collapsed when its first project became uneconomic, TerraPower absorbed a geopolitical shock, pivoted its reactor design, secured massive federal backing, and positioned itself for the data center power boom. These are the strategic moves that kept the company alive.
When the U.S. government banned nuclear cooperation with China in 2018, TerraPower lost its only path to building a prototype reactor. Rather than shutting down, the company redesigned its entire strategy around a new reactor concept — Natrium — optimized for U.S. deployment, U.S. regulatory approval, and commercial viability. The pivot took less than two years.
The 2022 HALEU fuel disruption caused by Russia's invasion of Ukraine pushed Natrium's timeline back by two years. But it also catalyzed domestic HALEU production at Centrus Energy's Piketon, Ohio facility and triggered billions in federal investment in uranium enrichment. TerraPower's delay may ultimately result in a more resilient fuel supply chain for all advanced reactors.
By selecting the retiring Naughton coal plant in Kemmerer, Wyoming, TerraPower gained existing transmission infrastructure, a skilled energy workforce, and strong community support. The coal-to-nuclear model has since become a template for other advanced reactor projects and aligns with federal just-transition policy for fossil fuel communities.
Meta's 2+ GW nuclear commitment and the broader explosion in AI-driven data center power demand have created a massive market for firm, carbon-free baseload power. Natrium's integrated energy storage — which allows power output to swing from 345 MWe to 500 MWe during peak demand — is uniquely suited to the variable load profiles of data center campuses.
TERRAPOWER TODAY: NATRIUM STATUS (2026)
As of May 2026, TerraPower is the furthest-advanced sodium-cooled fast reactor developer in the United States. On March 4, 2026, the NRC issued the construction permit for the Natrium demonstration plant in Kemmerer, Wyoming — the first construction permit ever issued for a commercial non-light-water reactor in the United States. This historic milestone clears TerraPower to begin nuclear construction. The company is targeting a 2030 operational date and remains private with no announced plans to go public.
The NRC issued the construction permit for Natrium on March 4, 2026 — the first CP ever issued for a commercial non-light-water reactor in the United States. This historic milestone clears TerraPower to begin full nuclear construction at the Kemmerer site.
With the construction permit issued, TerraPower is authorized to begin nuclear construction at the Kemmerer, Wyoming site — the location of the retiring Naughton coal plant. Site preparation work was already underway prior to CP issuance.
Centrus Energy began HALEU production at Piketon, OH in 2023. Production is ramping but initial quantities are limited. Multiple enrichment capacity expansion efforts are underway with DOE support. Supply chain risk is reducing but not eliminated.
Total funding exceeds $1 billion including the DOE ARDP cost-share of up to $2 billion. Bill Gates remains the largest private investor. SK Group and other strategic investors have also contributed. The company has not disclosed detailed financial breakdowns.
BOTTOM LINE
TerraPower is the most resilient advanced nuclear company in the United States. It survived the death of its original reactor concept when the China partnership was banned, pivoted to an entirely new design in under two years, secured the largest DOE advanced reactor award in history, weathered the HALEU fuel crisis, and positioned Natrium for the explosion in data center power demand. Bill Gates' continued financial commitment — rare for a billionaire founder in nuclear — provides a funding backstop that no other advanced reactor startup can match. With the NRC construction permit issued in March 2026 — the first ever for a commercial non-light-water reactor — TerraPower has cleared the most significant regulatory hurdle. HALEU supply remains constrained but domestic production is ramping. If Natrium achieves its 2030 target, it will be among the first advanced reactors to operate in the United States and a proof point for the coal-to-nuclear transition that could reshape American energy infrastructure.