Antares, a nuclear fission energy company based in Idaho Falls, has received approval from the U.S. Department of Energy (DOE) for its Preliminary Documented Safety Analysis (PDSA) concerning the Mark-0 reactor. The Mark-0 reactor is Antares' inaugural demonstration reactor, set to attain criticality by July 4, 2026, as part of the DOE’s Reactor Pilot Program. This approval marks a significant step forward for Antares in developing microreactors for defense and space applications. The DOE's certification of the PDSA paves the way for the reactor's progress.