The U.S. Department of Energy (DOE) has formally approved our Preliminary Documented Safety Analysis (PDSA) for the Mark-0 reactor—our first demonstration reactor, scheduled to go live before July 4, 2026. Mark-0 will validate fueling operations, reactor controls, and core physics.

This demonstration is a critical step toward generating electricity from advanced microreactors. Mark-0 uses a full-scale core and the same facility and fuel that will support our next reactor test in 2027.

The PDSA defines the preliminary safety basis for the reactor, facility, and planned operations, demonstrating that our approach meets DOE expectations at this stage. This approval validates our safety case and establishes a clear pathway to final acceptance as we prepare for fabrication, assembly, and installation.

Mark-0 will be tested at Idaho National Laboratory in Building 793—now the Reactors and Critical Experiments facility—a site with deep nuclear history. Decades ago, this building housed ML-1, the Army’s first mobile nuclear reactor. Today, it supports the next generation of deployable nuclear power. We find the historical relevance fitting and inspiring, as Antares develops a similar-scale microreactor to meet Army operational and installation needs.

Since 2024, we’ve worked to establish this facility as an enduring testbed, enabling rapid progress without the need for groundbreaking construction. We’re grateful for our partners at DOE and Idaho National Laboratory, and for leaders like Congressman Mike Simpson who continue to support the American nuclear renaissance.