Radiant Receives DOE Approval of Preliminary Documented Safety Analysis, Latest Milestone Towards Start-up of First Reactor

First-ever full-power test approval paves way for summer 2026 start up.

February 9, 2026

February 9th, 2026 – Radiant, a leader in portable, mass-produced nuclear microreactors, today announced that the U.S. Department of Energy (DOE) has granted approval of its DOE Authorization Request for Kaleidos (DARK). This documentation submitted by Radiant is designed to meet the intent of a Preliminary Documented Safety Analysis (PDSA), and approval allows Radiant to keep on track to start up its first reactor this summer.

This approval, the first granted for a full-power test, closes out the second of three nuclear safety document submittals in DOE’s new Authorization Pathway for Nuclear Facilities, paving the way towards reactor startup at the National Reactor Innovation Center’s (NRIC) Demonstration of Microreactor Experiments (DOME) facility at Idaho National Laboratory (INL).

“The DOE’s approval of our DARK submission is a major validation of Radiant’s safety-first approach and the strength of our reactor design,” said Dr. Rita Baranwal, Chief Nuclear Officer at Radiant. “Completing the second phase of the Authorization Pathway positions us to move confidently into start up activities and demonstrates that advanced nuclear systems can progress rapidly while meeting rigorous safety requirements.”

Radiant’s Kaleidos microreactor is designed to deliver reliable power in mission-critical environments, supporting both national security and commercial energy resilience objectives. The DARK approval reflects close collaboration between Radiant, DOE, and INL to establish a repeatable, efficient regulatory model for advanced nuclear deployments.

“Radiant's successful completion of this critical safety milestone marks rapid progress toward their reactor demonstration in DOME,” said John Wagner, Director of INL. “INL is proud to partner with Radiant to enable this achievement, which highlights how effective public-private partnerships -- leveraging our infrastructure and capabilities -- can accelerate the safe demonstration of microreactors.”

With this milestone complete, Radiant is now preparing for the final documented safety analysis submittal, and readiness review, leading to authorization and startup of its first reactor at INL this summer.

For more information on Radiant and the Kaleidos generator, visit www.radiantnuclear.com.

About Idaho National Laboratory

Battelle Energy Alliance manages INL for the U.S. Department of Energy's Office of Nuclear Energy. INL is the nation's center for nuclear energy research and development, and also performs research in each of DOE's strategic goal areas: energy, national security, science and the environment. For more information, visit www.inl.gov. Follow us on social media: Facebook, Instagram, LinkedIn and X.