Radiant Receives First TRISO Fuel for Kaleidos Reactor at INL DOME
Radiant received its first tranche of Standard Nuclear TRISO fuel at Idaho National Laboratory's DOME facility on July 1, 2026, clearing the way for a five-phase, full-power test of the transportable Kaleidos microreactor this summer.
Key Takeaways
Radiant received its first tranche of Standard Nuclear TRISO fuel at Idaho National Laboratory's DOME facility on July 1, 2026, enabling full-power testing of its Kaleidos microreactor this summer.
The five-phase test program progresses from zero-power criticality to 1 MW thermal, full power, and full heat, culminating in at least 150 hours of full-power operation without operator intervention.
Kaleidos is a 1 MW-electric, 3 MW-thermal transportable microreactor in a single shipping container, targeting diesel generator replacement and power for defense sites, hospitals, and AI data centers.
Radiant is the only developer currently authorized to test at DOME and aims for commercial customer delivery in 2028, with test data feeding its Part 70 NRC license application for the R-50 fuel-handling facility in Tennessee.
The TRISO fuel, ceramic-coated uranium particles engineered to be meltdown-proof, was fabricated by Oak Ridge-based Standard Nuclear and shipped in a Radiant-designed transport system.
Kaan Tınmaz
El Segundo-based nuclear developer Radiant announced on July 1, 2026 that it has received its first tranche of tri-structural isotropic (TRISO) nuclear fuel at Idaho National Laboratory's Demonstration of Microreactor Experiments (DOME) facility, clearing the path to full-power, full-temperature testing of its Kaleidos microreactor this summer.
Standard Nuclear Delivers Custom-Made TRISO Fuel
The TRISO fuel was fabricated by Oak Ridge, Tennessee-based Standard Nuclear to Radiant's specifications earlier in 2026 and shipped to INL in a Radiant-designed transport system. TRISO — ceramic-coated uranium particles proven in more than 30 grid-scale reactors since the 1960s — is engineered to be meltdown-proof and forms the heart of a growing class of high-temperature gas-cooled microreactors moving through the Department of Energy's pilot pipeline alongside Aalo Atomics, Antares, Valar Atomics and Deployable Energy.
Five-Phase Test Program Targets 150 Hours Unattended
With fuel now on site, Radiant is preparing to bring Kaleidos online through a five-phase program progressing from zero-power criticality to 1 MW thermal, full power, and full heat — culminating in at least 150 hours of full-power operation without operator intervention. "We are de-risking a commercial product that will be manufactured and delivered within 18 months," said Chief Nuclear Officer Dr. Rita Baranwal. Data from the campaign will feed Radiant's Part 70 license application for its R-50 fuel-handling facility in Tennessee, currently under accelerated NRC review.
Racing to Power AI Data Centers
Kaleidos is a 1 MW-electric, 3 MW-thermal transportable microreactor packaged in a single shipping container, designed to replace diesel generators and to serve as backup — or off-grid prime — power for defense installations, hospitals and AI data centers. Radiant is the only developer currently authorized to test at DOME, and the company is aiming for commercial customer delivery in 2028. The milestone caps a month in which four DOE-authorized advanced reactors reached criticality at INL and Utah's San Rafael Energy Lab, marking a nuclear renaissance the White House is racing to accelerate.
Reporting based on coverage from Business Wire, World Nuclear News and POWER Magazine.
TRISO (tri-structural isotropic) fuel consists of ceramic-coated uranium particles engineered to be meltdown-proof. Proven in more than 30 grid-scale reactors since the 1960s, it powers a growing class of high-temperature gas-cooled microreactors in the Department of Energy's pilot pipeline.
What will Radiant's Kaleidos test program at INL involve?
A five-phase program at INL's DOME facility progressing from zero-power criticality to 1 MW thermal, full power, and full heat, culminating in at least 150 hours of full-power operation without operator intervention.
When will Kaleidos be commercially available?
Radiant is targeting commercial customer delivery in 2028, and Chief Nuclear Officer Dr. Rita Baranwal said the tests de-risk a commercial product to be manufactured and delivered within 18 months.
What is the Kaleidos microreactor designed to power?
Kaleidos is a 1 MW-electric, 3 MW-thermal transportable microreactor packaged in a single shipping container, designed to replace diesel generators and provide backup or off-grid prime power for defense installations, hospitals, and AI data centers.
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