TerraPower

Type: Company — Private SMR developer (sodium fast reactor)

TerraPower is building the Natrium reactor — a 345 MWe sodium-cooled fast reactor with integrated molten-salt thermal energy storage (TES), enabling the output to flex up to 500 MWe for 5.5+ hours when grid demand peaks. Founded by Bill Gates, backed by Gates's Breakthrough Energy and various institutional investors. The Natrium project is the most advanced construction-stage advanced reactor in the US.

Natrium Project (Kemmerer, Wyoming)

• Site: Wyoming Integrated Test Center site near retiring PacifiCorp coal plant in Kemmerer, WY
• Status: Non-nuclear construction has begun (civil works, site prep); no NRC construction permit yet
• NRC timeline: Environmental review complete (Oct 2025); final safety evaluation issued (Dec 2025); construction permit decision expected H1 2026
• Target: First power 2030 (DOE demonstration project under ARDP program)
• Cost: ~$4B project cost; DOE provides ~$2B in ARDP cost-sharing

Technology

• Sodium-cooled fast reactor (SFR): Higher efficiency, can use a broader range of uranium fuel; breeds plutonium (closed fuel cycle potential)
• Molten-salt TES: 500 MWh of thermal storage; reactor runs flat, grid output flexes with demand — hybrid baseload+storage
• Output: 345 MWe base; 500 MWe peak (5.5+ hrs)
• Fuel: HALEU required (initially imported from Russia; DOE working on US supply)

Key Facts

• DOE Advanced Reactor Demonstration Program (ARDP) award: ~$2B (50% cost share)
• Co-investors: PacifiCorp (utility partner), Wyoming state government
• Kemmerer site: former coal plant = existing grid connection + workforce familiarity

Key Claims (new sources)

• TerraPower anchors Meta's up-to-6.6 GW deal: up to eight Natrium reactors plus storage, with two units online as soon as 2032 — a full 2.6 GW nuclear + 1.2 GW storage. Evidence: weak (single news item, Latitude Media)
• TerraPower completed its safety evaluation in Dec 2025 but did not yet hold an NRC construction permit at the time of the Meta deal. Evidence: weak (single news item, Latitude Media) — corroborates the Dec 2025 final safety evaluation noted above.

Outstanding Questions

• Will NRC issue the construction permit in H1 2026 as expected?
• Is 2030 first-power achievable given permit timing?
• What is the US HALEU supply plan? (Natrium needs HALEU; domestic supply is near-zero)
• Does the Natrium economics at $4B for 345-500 MWe pencil for utilities beyond the DOE demo?
• Can TerraPower deliver two units for Meta by 2032 without an NRC construction permit yet in hand?

Changelog

• 2026-06-24 — Compiled new sources (meta-66gw-nuclear-deal)