US start-up Radiant Industries says the US DOE has reviewed and approved the Safety Design Strategy for’ Kaleidos microreactor in the National Reactor Innovation Center’s Demonstration of Microreactor Experiments (NRIC-DOME) test bed at the Idaho National Laboratory (INL). 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 Idaho facility.

Radiant Industries was set up in 2019 by former SpaceX engineers. Its Kaleidos design is a high-temperature gas-cooled reactor (HTGR) which will use TRISO fuel, a helium coolant, and a graphite moderator. All components will be fitted in a single shipping container to facilitate rapid deployment. It is designed to produce 1.2MWe or 1.9 MWt for heating or water desalination, as a potential replacement for diesel generators. Following testing that is scheduled to begin in 2026, Radiant targets commercial production units in 2028, after obtaining US Nuclear Regulatory Commission (NRC) licences.

In October 2023, Radiant was selected as one of three advanced nuclear energy developers to receive funding from DOE for developing and testing microreactor designs using the DOME test bed at INL. DOE, through NRIC, awarded $3.9m to Radiant, Ultra Safe Nuclear Corporation (UNSC) and Westinghouse to design experiments to test microreactor designs at DOME.

Testing in NRIC’s DOME will allow Radiant to gather critical safety and performance data to support the future commercial licensing process with the NRC. Radiant said it is currently working with INL on the next phase of the safety review, focusing on the Conceptual Safety Design Report (CSDR). The purpose of the CSDR is to summarise the hazard analysis efforts and safety-in-design decisions incorporated into the conceptual design, along with any identified project risks associated with the selected strategies.

“The SDS is the cornerstone of the safety roadmap we’re building as we approach commercialisation of a fuelled reactor in a few years’ time,” said Radiant CEO Doug Bernauer. “We’re grateful for DOE Idaho’s review and approval as we take this important step forward and for INL’s continued thorough support throughout this critical process.”

Brad Tomer, acting director and Chief Operating Officer at NRIC said approval of the SDS “is an important step towards enabling a microreactor developer to perform a test in our DOME facility”. He added: “As the nation’s nuclear energy research laboratory, we are committed to working with private companies to help further develop advanced nuclear technologies that will provide clean energy solutions for the US.”