DOE approves documented safety analysis for Radiant's Kaleidos microreactor
Testing at Idaho National Laboratory will run 60 effective full power days, ending with at least 150 hours at full power without operator intervention.
Key facts
- Approval covers operation at power as well as first criticality; next step is DOE Readiness Review
- Kaleidos was built in El Segundo, California and shipped to Idaho National Laboratory in August 2026
- Five-phase campaign runs at INL's Demonstration of Microreactor Experiments facility, starting at first criticality
- First commercial units planned for Buckley Space Force Base and Fort Benning in 2028, per Radiant
- DOE approved Radiant's earlier preliminary safety analysis in February 2026
The U.S. Department of Energy (DOE) approved Radiant's documented safety analysis (DSA) for the Kaleidos microreactor, the company said on October 29, allowing the design to advance to DOE's Readiness Review before nuclear operations at Idaho National Laboratory (INL). The approval covers operation at power as well as initial criticality.
Radiant plans a five-phase test campaign at the National Reactor Innovation Center's Demonstration of Microreactor Experiments (DOME) facility. After the readiness review, Radiant will fuel Kaleidos and begin the campaign, progressing from first criticality to at least 150 hours of continuous full-power operation without operator intervention. Radiant plans to run the same unit for 60 effective full power days (EFPD) over several months.
Radiant built Kaleidos at its El Segundo, California facility and shipped it to INL in August 2026. DOE approved an earlier preliminary DSA in February 2026. Radiant plans to manufacture Kaleidos at its R-50 facility in Oak Ridge, Tennessee, and deliver first commercial units to Buckley Space Force Base and Fort Benning in 2028. Earlier this month, the U.S. Navy selected Radiant to deploy Kaleidos at Naval Weapons Station Crane in Indiana.
