The Space Nuclear Power Corporation, known as SpaceNukes, has received an other transaction agreement from the Defense Advanced Research Projects Agency to design, build and ground test a kilopower reactor with Los Alamos National Laboratory. The company announced the award, and the American Nuclear Society reported it on October 26. The dollar value was not disclosed in the report.
The work falls under DARPA's Fast Capacitance program, called Fat Cat, which aims to advance reactor operations, including reactors designed for propulsion systems, as a power source for extreme and remote environments. The program is managed by Tabitha Dodson in DARPA's Defense Sciences Office. Its goal is to demonstrate autonomous nuclear control on a fully functional fast reactor with Los Alamos at the Device Assembly Facility.
SpaceNukes and the laboratory will design an autonomous reactor and take the project through procurement, integration and a ground demonstration. The design will use active control rod operation. The 2018 KRUSTY test used a passively controlled architecture. KRUSTY, the Kilopower Reactor Using Stirling Technology, was a 5-kilowatt-thermal solid-fuel uranium-235 reactor with boron carbide control rods that NASA led in tests during 2017 and 2018.
Small fast reactors operate without a moderator, so their faster neutrons and smaller control rods make them highly responsive. The Fat Cat program notes that rapid transients can be too complex for human operators to manage alone, which creates a need for reliable autonomous controllers.
Marc Gibson, chief engineer at SpaceNukes and former lead engineer for the Kilopower Project at NASA, will lead integration. Chief technical officer David Poston and chief operating officer Patrick McClure also worked on Kilopower at Los Alamos.
Source: ANS Nuclear Newswire - https://www.ans.org/news/2026-10-26/article-8520/spacenukes-receives-darpa-award-to-ground-test-kilopower-reactor/