Hermes
Hermes is Kairos Power's 35 MWth fluoride salt-cooled reactor demonstration unit for FHR technology.
Hermes uses TRISO pebbles in FLiBe salt primary coolant at 600°C, with passive decay heat removal. It supports KP-FHR development and fuel testing. Construction started 2024 on Oak Ridge site with DOE funding.
Why it matters now
Hermes low-power demo accelerates FHR licensing path for data center heat and power. 2025-2026 milestones include criticality, informing SMR deployments amid Google PPA.