US DOE Approves Safety Analysis for Antares' Mark-0 Reactor Development
The US Department of Energy (DOE) has approved the Preliminary Documented Safety Analysis (PDSA) for the Mark-0 reactor developed by Antares, a California-based nuclear start-up. Antares, founded in 2023, is part of the DOE's Reactor Pilot Program initiated by Executive Order 14301, aiming for three reactors to achieve criticality by July 4, 2026.
The company received a Nuclear Safety Design Agreement from the DOE in October 2025. Antares is targeting a low-power demonstration unit to be operational before July 4, 2026, with plans for an electricity-producing unit (Mark-1) in 2027 and a commercial R1 microreactor design for 2028.
Testing will occur at Idaho National Laboratory. Antares has secured over $40 million in Idaho and has raised $30 million in Series A and $96 million in Series B funding for reactor production. The company has contracts with the Department of Defense and NASA, aiming to deploy microreactors for military and space applications.
