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Radiant · Idaho National Laboratory (DOME), ID · IdahoDEVELOPER HEALTHWATCH
Portable high-temperature gas microreactor; the first test in INL's DOME facility, with a five-phase program ending in 150+ hours at full power. Commercial units targeted for 2028.
Power
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Fission · Research and prototype
Storage
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energy capacity
Online
Q3 2026
actual
Capital committed
—
closed or awarded
Capital pending
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conditional or under review
How it works
Fuel is packed in tough ceramic-coated particles (TRISO), often in billiard-ball pebbles, and cooled by helium gas. Runs much hotter than water reactors, which suits industrial heat.
OPEN IN 3D →Others on this approach
DOE authorizedDOCKET 99902106
issued Oct 29, 2026
DOE approved Radiant's safety analysis for Kaleidos full-power operation at INL's DOME on October 29, 2026, and Radiant is next due for a DOE readiness review before fueling and starting the five-phase test. Separately, the NRC docket for Kaleidos (99902106) remains at pre-application, with the NRC's separate Part 70 review covering Radiant's R-50 fuel facility in Oak Ridge, not a Kaleidos reactor application.
NEXT: DOE Readiness Review, then fueling and the five-phase test campaign at DOME (zero-power criticality through a 150-hour continuous run); NRC expects a separate Kaleidos application in the near future.
No project-level financing disclosed yet.
Grid connection, permits, contractors and cost not researched yet for this project.
Not applicable: test or demonstration machine, sells no power
STEP 4/6 · AT RISK HALEU is the bottleneckMost advanced designs need HALEU (5–20% enriched), with no commercial US supply at scale yet.
STEP 4/4 · WATCH Office relaunched as Energy Dominance FinancingLending shifts toward nuclear and utility expansions (AP1000 offers, Constellation uprates).
Critical inputs
Policy that applies