The brief

Analyst view

• Kaleidos is 1 MWe, using TRISO fuel and helium gas, with passive 300 ms emergency shutdown requiring zero water.
• Raised $525M by December 2025; first reactor shipped to Idaho National Laboratory in August 2025.
• First commercial units planned for 2028, starting with Buckley Space Force Base in Colorado.

Technical approach

As reported

Fuel

TRISO particle fuel in graphite blocks

Ceramic-coated uranium particles withstand extreme heat without melting, enabling gas cooling instead of water.

Cooling

Helium gas and passive shutdown

Helium circulates to carry heat away. On power loss, gravity and natural convection cool passively in 300 ms.

Portability

Factory-built and transportable

The 1 MW core ships in a sealed canister. Modular design fits containers and cuts on-site construction from months to weeks.

Manufacturing

R-50 factory for scale

Oak Ridge, Tennessee factory targets 50 reactors per year by decade's end.

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