Valar founder and CEO Isaiah Taylor has indicated the Ward 250 is a 100-kWt reactor built to demonstrate the company’s TRISO-fueled high-temperature gas reactor technology. Criticality, the DOE noted, demonstrates that the reactor can sustain a controlled nuclear chain reaction—a first step that must be achieved before it can generate power. Valar Atomics previously announced zero power criticality in an experimental core at Los Alamos National Laboratory in November 2025.
Meeting the deadline: The demonstration marks the second reactor criticality tied to President Trump's May 2025 executive order directing the DOE to bring multiple advanced reactors critical by July 4.
Energy Secretary Chris Wright called it "another historic moment for America's nuclear renaissance," adding that "Valar Atomics is delivering achievements that mark a revolutionary moment for advanced nuclear in this country."
Taylor, quoted in the same DOE release, said, "Nine months ago, this was an empty site. Today, there's a critical reactor on it, built and operated by the Valar team." He added that "this reactor was built to make power, and that's exactly where we're headed."
Inside the start-up: The criticality cleared a federal review process that has been led by Bob Boston, a manager at the DOE’s Idaho Operations Office. Writing on LinkedIn, Boston explained that before the criticality test was authorized by the DOE, the Ward 250 required a joint test group (JTG) to sign off on the key steps of the reactor start-up. Boston thanked the federal team he credited with getting Ward 250 "across the finish line."
USREL sits just outside Orangeville, Utah, and is operated by the state under the Office of Energy Development. As previously reported, the project aligns with Gov. Spencer Cox's Operation Gigawatt, which aims to double the state's power production within a decade. Former USREL director and ANS Congressional Fellow Jeremy Pearson has described the site—flanked by gigawatt-scale coal stations and active coal mines—as an ideal proving ground for nuclear industrial-heat pilots.
The bigger picture: With Antares and Valar now critical, the executive order's three-reactor target by July 4 is still unmet. Among the companies looking to mark a criticality milestone soon are Aalo, Radiant, and Deployable Energy, all of which have received their documented safety analysis from the DOE.
