Natrium
345 MWe sodium-cooled fast reactor with molten-salt energy storage boosting output to 500 MWe; first unit under construction at Kemmerer, Wyoming, under DOE's Advanced Reactor Demonstration Program.
Development
Startup · United States
TerraPower
HQ BellevueFounded 2008
Developer of the Natrium sodium-cooled fast reactor with molten-salt storage; the first plant (Kemmerer Unit 1, Wyoming) received an NRC construction permit in March 2026. Also produces medical isotopes.
Systems1
Newest unveiled first. Open a system for its milestone timeline, components and sources.
Capabilities2
| Technology | Role | Maturity | TRL | Notes | Confidence |
|---|---|---|---|---|---|
| Advanced fission reactors | Developer | Development | — | Natrium (345 MWe sodium fast reactor, boostable to 500 MWe with storage) is above the BRIEF's SMR size band, so linked at capability level. | Confirmed |
| Small modular reactors | Developer | Development | — | DOE, World Nuclear News and ANS call Natrium a small modular reactor even though its 345 MWe (500 MWe with storage) output is above the BRIEF's ~300 MWe SMR band; the capability-level link from batch B stays. | Reported |
- DeveloperNatrium (345 MWe sodium fast reactor, boostable to 500 MWe with storage) is above the BRIEF's SMR size band, so linked at capability level.DevelopmentConfirmed
- DeveloperDOE, World Nuclear News and ANS call Natrium a small modular reactor even though its 345 MWe (500 MWe with storage) output is above the BRIEF's ~300 MWe SMR band; the capability-level link from batch B stays.DevelopmentReported
Maturity and TRL describe this organization's work; the field-wide maturity is on each technology's page.
People4
- Bill Gates
Founder
- Chris Levesque
president and chief executive officer
- John Gilleland
chief technical officer
- Scott Claunch
president
Sources7
Profile2
- 1
TerraPower · Supports Organization · website
“Our first Natrium plant is currently being built in Wyoming.”
- 2CompanyAbout TerraPower
TerraPower · Supports Organization · founded year
“a company founded by Bill Gates (chairman), Nathan Myhrvold (vice chairman) and Dr. Gilleland in 2008”
Systems2
- 3
TerraPower · Mar 4, 2026 · Supports Organization · hq city, Organization technology, System
“Bellevue, WA – March 4, 2026 – TerraPower, a nuclear innovation company”
- 4Government recordU.S. Department of Energy Restores Key Safety Test for Nuclear Fuel
U.S. Department of Energy · Oct 4, 2023 · Supports Organization technology, System · system technology:small-modular-reactors
“The larger rig will also be used for upcoming sodium loop tests to support the development of TerraPower’s Natrium small modular reactor.”
Technologies2
- 5
World Nuclear News · Aug 21, 2026 · Supports Organization technology
“In December 2024, US small modular reactor (SMR) developer TerraPower selected suppliers for the reactor's enclosure system.”
- 6
American Nuclear Society (Nuclear News) · May 24, 2024 · Supports Organization technology
“The U.S. Nuclear Regulatory Commission has formally accepted TerraPower’s small modular reactor construction permit application and is scheduling it for review.”
People1
- 7CompanyAbout TerraPower
TerraPower · Supports Role
“Scott Claunch is president of TerraPower Isotopes®, a division of TerraPower focused on the pursuit of next-generation therapeutic medical isotopes for Targeted Alpha Therapy (TAT) treatments.”
Each fact on this page is attached to the sources that support it. Archived copies are linked when we keep one.