Under ConstructionAdvanced Non-LWR
Project website →Hermes I
📍 Oak Ridge, TN (Anderson County Co.)Developer: Kairos PowerVendor / Tech: Kairos Power
Capacity
35 MW
Expected Operation
2027
Reactor Type
KP-FHR (Fluoride-salt cooled)
Regulatory Status
Under construction (safety-related nuclear construction since 2025-05); NRC extended CP construction-completion deadline from 2026-12-31 to 2029-04-30
Details
Primary Use
Nuclear heat demonstration (no electricity generation)
Grid Connection
TVA grid (future)
Fuel Type
HALEU / TRISO
Construction Start
2024
Research detail · verified 2026-10-10
Stage
Under construction
Commercial power
No (test, research, military or demonstration)
NRC docket
50-7513 (CP No. CPTR-6)
Stated target operation
Construction completion anticipated in 2028 (stated by Kairos, reported by WNN 2026-04)
Stated operations jobs
More than 55 full-time jobs (Kairos, 2024-07-30 construction-start release); up to 100 jobs in East Tennessee across Oak Ridge campus (Kairos/DOE)
Key dates
2023-12 NRC construction permit issued; 2024-07 groundbreaking; 2024-10 excavation completed; 2025-05 safety-related construction began; 2026-03-24 Kairos requested CP completion-date extension; 2026-04/05 NRC approved extension to 2029-04-30
Workforce
NuCAMP (Nuclear Center for Advanced Manufacturing and Precast) launched 2026-08 at Kairos Oak Ridge campus with ORNL, University of Tennessee-Knoxville, IACMI, Barnard Construction, Roane State Community College, Chattanooga State Community College and Oak Ridge Schools; year-long exploration phase for welding, additive manufacturing and precast concrete training; TVA provides engineering and operations support; Barnard Construction general contractor
Not verified / conflicts
Extension approval date conflict: WNN reports NRC extended the deadline on 2026-04-21; Federal Register notice (2026-09880) says the Order was issued 2026-05-13 (EA/FONSI may have preceded the order). Original 2024-07 Kairos release targeted operation in 2027; superseded by 2028 completion. Docket 50-7513 from Federal Register search snippet; PDF not opened directly.
Sources
- https://wnn.world-nuclear.org/articles/regulator-extends-hermes-1-reactor-construction-deadline
- https://public-inspection.federalregister.gov/2026-09880.pdf
- https://kairospower.com/updates/kairos-power-begins-construction-on-hermes-low-power-demonstration-reactor
- https://kairospower.com/tennessee/
- https://ans.org/news/2026-08-20/article-8310/kairos-power-others-launch-nucamp-to-develop-nuclear-workforce
- https://www.energy.gov/ne/articles/kairos-power-starts-construction-hermes-reactor
About
35 MWt. First non-light-water reactor approved for construction in US in 50+ years. First concrete poured May 2025. First advanced (Gen IV) reactor developer to receive NRC construction permit AND begin nuclear component construction in the US. Nuclear concrete pours started 2025.
Key Organizations
Developer
Kairos Power
EPC Contractor
Barnard Construction
Power Purchase Agreements1 PPA
N/A (non-power demonstration)
announcedPrivate Funding
DOE ARDP
Equity
—
announced
Federal Funding
DOE
DOE Funding ·
DOE ARDP up to $303M
—
awarded
State Policy Context
View nuclear-related legislation and energy stats for Tennessee