Valar Atomics Achieves Criticality in Nuclear Reactor Under DOE Pilot Program

Valar Atomics' Ward 250 reactor reached zero-power criticality on June 18, 2026, marking the second advanced reactor to achieve this milestone under the U.S. Department of Energy's Reactor Pilot Program. This event demonstrates a self-sustaining nuclear fission chain reaction, crucial for future power generation. The reactor is located at the Utah San Rafael Energy Lab and is designed to scale from 100 kWt to 5 MWe. Valar Atomics aims to meet the goal of three reactors reaching criticality by July 4, 2026, as mandated by Executive Order 14301. The first reactor, Antares Nuclear's Mark-0, achieved criticality on June 4, 2026. The success of Ward 250 signifies a significant step in revitalizing the U.S. nuclear industry, which has faced decades of stagnation. Valar's CEO, Isaiah Taylor, emphasized the importance of hardware iteration in nuclear development. The reactor's design incorporates advanced safety features and utilizes TRISO fuel technology.

Key Points: • Ward 250 achieved zero-power criticality on June 18, 2026, under the DOE's Reactor Pilot Program. • This marks the second advanced reactor to reach criticality, following Antares Nuclear's Mark-0. • The reactor is designed for scalability from 100 kWt to 5 MWe, aiming for operational power by July 4, 2026.