Radiant Nuclear

Nucleation first invested into Radiant in Q4 2021 and we've since made two follow-on investments. 

Radiant is developing Kaleidos, a 1 MW gas-cooled, graphite-moderated microreactor using TRISO fuel pressed into cylindrical compacts that are then loaded into prismatic graphite moderator blocks.

We’re thrilled to announce Nucleation Capital Fund I's third and largest investment in Radiant Industries, a company that has made remarkable progress towards testing and launching Kaleidos, its Gen IV microreactor.

Radiant was already one of the leaders in this space when the DOE announced ten ventures selected for the New Reactor Pilot Program in August 2025, including Radiant, to receive special DOE support and setting off a race to initial criticality by July 4th, 2026. Radiant had already been selected by the DOE to be the first venture to utilize the new DOME test bed, beating out Westinghouse for the #1 test slot, for a six-month testing window that starts in 2026, and was already building its Kaleidos microreactor for this purpose when the DOE challenged the sector to achieve crticality by July 4th, an almost impossible and previously unheard of rapid time frame in which to accomplish this very complicated feat.

This company has long been positioned as one of the leading developers in this space and, in a sign of its emerging market leadership, Radiant successfully hired Dr. Rita Baranwal, the brilliant former Assistant Secretary for Nuclear Energy (initially appointed to that office by President Trump in his first term) away from Westinghouse in June 2025 to serve as Chief Nuclear Offier. This provides clear evidence of Radiant's commitment to embracing the standards of a more mature nuclear organization. Dr. Baranwal, now a member of the company leadership, has already made significant contributions towards improving Radiant's industry credibility and regulatory performance, even as it continues to execute at a superior level, pairing technological innovation progress with meaningful organizational growth with continued strong financial support from investors.

Radiant's pedigree—having successfully developed SpaceX’s reverse-in landing system—brings a rapid build-test-iterate ethic to its development of scalable microreactors. The company has already built and tested most sub-components of Kaleidos, their flagship 1 MWe “power system in a box.” Kaleidos passed an important passive safety test in October 2024. This work enabled the team to submit its Preliminary Documented Safety Analysis (PDSA) to the DOE in November of 2025, which started a 45-day approval process. As of early February, 2026, Radiant has now become the first Gen IV venture to receive DOE approval of its PDSA, paving the way for the company's DOME testing and criticality start-up in the summer of 2026.

Radiant is currently on track to complete construction, deliver by truck, set up and test the Kaleidos Development Unit prototype at the Idaho National Laboratory (INL)’s Demonstration of Microreactor Experiments (DOME) facility in the spring of 2026. At DOME, Radiant will conduct an intensive battery of tests, validate its models, achieve criticality to meet the President's goal, and collect crucial performance data that will enable it to expeditiously submit its Nuclear Regulatory Commission application and potentially obtain the required commercial NRC certifications that will unlock Radiant's ability to deliver against its growing commercial sales pipeline.

Within a few weeks of Radiant's selection to be the first company to utilize the DOME testing facility, the team annouced that it had signed a contract with the Defense Innovation Unit (DIU) and the Department of the Air Force to provide its mass-manufactured microreactors to a U.S. military base starting in 2028. The signed agreement, authorized under the Pentagon's Advanced Nuclear Power for Installations (ANPI) program, calls for Radiant's reactors to be delivered by truck within 36 months, powered on within 48 hours of delivery to provide resilient, cyber-secure power for years without refueling, thereby helping to harden U.S. defense capabilities.

In furtherance of this goal, Radiant studied potential manufacturing locations and secured a large parcel of former Manhattan Project land in Oak Ridge, Tennessee, on which to build a factory that will mass-produce the Kaleidos reactors. The company has already begun planning the design of the Radiant "R-50" plant and intends to start construction in early 2026 of the R-50 which will have sufficient space to scale to build up to 50 units a year, with first units rolling off the line by 2028.

This incredible progress and the accelerated timelines enabled by the Trump Nuclear Executive Orders, the DOE's New Reactor Pilot Program, the ANPI delivery schedule and the urgency of meeting decarbonization goals, motivated Radiant to raise its over-subscribed Series D ahead of schedule and less than a year after closing its Series C. We are delighted to have once again joined a large and diverse group of investors, this time led by Draper Associates and Boost VC, with strong conviction about Radiant's ability to execute on its vision, now including Lockheed Martin, a premier defense industry player, and to participate in providing funding that will help fuel Radiant's growth through its DOME test, construction of the R-50 facility and early revenue.