Valar Atomics' Ward 250 reactor successfully completed a zero-power fueled criticality demonstration on June 18, 2026 at the Utah San Rafael Energy Lab in Emery County, Utah. This marks the first DOE authorized reactor built outside of a national laboratory. The reactor was built in approximately 9 months from an empty site. It is the second of multiple advanced reactors anticipated to go critical by the July 4th deadline set by President Trump in his May 2025 executive order. The criticality test demonstrates the reactor can sustain a controlled nuclear chain reaction.