Kairos Power
Mike Laufer
Overview
Kairos Power is commercializing its fluoride salt-cooled, high-temperature reactor (KP-FHR), which combines TRISO pebble fuel with FLiBe coolant in a compact, low-pressure design. The company is using an iterative, vertically integrated development model centered on Hermes 1, a 35 MWth demonstration reactor under construction in Oak Ridge, and Hermes 2, an electricity-producing demonstration plant for the TVA grid. In April 2026, Kairos broke ground on Hermes 2, the first deployment under its Google-backed fleet plan totaling up to 500 MWe by 2035.
Main Products
35 MWth low-power demonstration reactor validating Kairos Power's KP-FHR design, construction methods, fuel program, and operating approach in Oak Ridge, Tennessee.
Construction permit granted in December 2023 and nuclear safety-related construction began in May 2025. In May 2026 the NRC extended the construction-completion deadline by 28 months to April 30, 2029 after first-of-a-kind site and design delays; Kairos now expects to finish building the reactor in 2028, pushing operation past the original 2027 target.
Commercial-scale demonstration plant that extends the Hermes learning loop into electricity production for the TVA grid and Google-backed demand.
NRC construction permits were issued in November 2024; Kairos has re-envisioned Hermes 2 as a single-reactor, up-to-50 MWe plant scheduled to begin operations in 2030.
Kairos Power's modular commercial reactor platform for grid, data center, and industrial users, designed around paired 75 MWe units that scale into larger multi-unit plants.
Commercial fleet architecture is now anchored by Kairos Power's Google agreement, with first deployment targeted for 2030 and additional projects through 2035.
What's Next
Completing construction, fuel loading, and startup of the Hermes 1 low-power demonstration reactor in Oak Ridge to validate Kairos Power's reactor, fuel, and operating model. After a May 2026 permit amendment, Kairos expects to finish building Hermes 1 in 2028, with the NRC construction-completion deadline now set at April 30, 2029.
Operations & Revenue
Development stage — Hermes 1 safety-related construction began in May 2025, Hermes 2 broke ground in April 2026, and first grid power under the TVA agreement is targeted for 2030. Kairos has no operating reactors yet.
Key Metrics
Timeline
The NRC approves Kairos Power's request to extend the latest date for completing Hermes 1 construction by 28 months, from December 31, 2026 to April 30, 2029. Kairos cited first-of-a-kind site-prep and design work — including removing legacy structures from the test-reactor footprint in coordination with the DOE — and now expects to finish building the Hermes test reactor in 2028.