California-based startup Radiant Nuclear (formerly Radiant Industries) has raised more than $300m in a new round of funding just six months since closing its Series C round in June. Radiant said this will support the scaling of commercialisation efforts as it prepares to break ground early next year on its recently announced R-50 microreactor reactor factory in Oak Ridge, Tennessee.
This new round, led by Draper Associates and Boost VC, also includes additional financial commitments from current investors. As part of this latest capital raise, Radiant also received additional investment from Founders Fund, ARK Venture Fund, Chevron Technology Ventures, and others.
Radiant’s Kaleidos microreactor design is a transportable high-temperature gas-cooled reactor (HTGR) using high-assay low-enriched uranium (HALEU) tristructural-isotropic (TRISO) fuel, helium gas coolant, and prismatic graphite blocks. It has a capacity of 3 MWt or 1 MWe. Each 70-tonne microreactor will fit into a single shipping container. Radiant says the reactor can set up to be producing power within 48 hours of delivery at a customer site. The reactor has a five-year fuel cycle and a 20-year service life. Refuelling is carried out at a remote maintenance facility.
In October, Radiant said it will be on track to deliver its first mass-produced Kaleidos nuclear generator by 2028 and, within a few years, it will scale up production to 50 reactors a year. The company said it remains on track for next year’s startup of its first reactor – the Kaleidos Demonstration Unit (KDU) – at Idaho National Laboratory’s (INL’s) Demonstration of Microreactor Experiments (DOME) facility currently under construction at INL’s National Reactor Innovation Center (NRIC).
Radiant Industries was set up in 2019 by former SpaceX engineers. It has benefitted from significant Department of Energy (DOE) support. In October 2023, Radiant was selected as one of three advanced nuclear energy developers to receive funding totalling $3.9m from DOE for developing and testing microreactor designs using DOME.
In June 2024, DOE approved the Safety Design Strategy for the Kaleidos microreactor at the DOME test bed. The SDS, which describes the accepted safety analysis approach for the Kaleidos reactor, marks the initial stage in a comprehensive safety review process each microreactor developer must undertake before a fuelled test at the INL facility. The following November Radiant completed the front-end engineering & experiment design (FEED) phase required prior to the DOME tests. The FEED process supports developers in designing and planning for the fabrication, construction, and potential testing of fuelled reactor experiments at DOME.
In April Radiant was one of five companies selected by DOE to receive high-assay low-enriched uranium (HALEU) to meet their near-term fuel needs. DOE created the HALEU allocation process for nuclear developers to request HALEU material from DOE sources, including material from the National Nuclear Security Administration (NNSA). In July, DOE formally selected Westinghouse and Radiant as the first companies to perform the tests using DOME.
In August, DOE launched (DOE) the Nuclear Reactor Pilot Program, naming ten companies with 11 advanced reactor projects that DOE will initially support to move their technologies towards deployment. Radiant was one of the companies selected with the aim of achieve criticality of at least three test reactors using the DOE authorisation process by 4 July 2026.
Also in August, Radiant signed an agreement with the Defense Innovation Unit (DIU) and the Department of the Air Force to deliver a first-of-a-kind (FOAK) microreactor to a US Air Force military base in 2028. The value of the contract and the location of the base were not disclosed. Radiant had previously received funding awards from the US Department of Defense (DOD) to evaluate the integration of microreactors at the Hill Air Force Base near Salt Lake City in Utah.
Radiant also signed a preorder deal in August with Equinix, a leader in digital infrastructure, for the supply of 20 reactors to power is data centres.
Commenting on the latest funding, Doug Bernauer, CEO and Founder of Radiant, noted: “This funding enables us to build our factory and keep to our DOME schedule, where we will achieve self-sustained chain reaction on a reactor designed by, built by, fuelled by, and operated by Radiant alongside our partners at the Idaho National Lab.”
