On June 18, 2026, Valar Atomics’ Ward 250 reactor completed a zero-power fueled criticality demonstration at the Utah San Rafael Energy Lab in Emery County—marking the second advanced reactor to reach this milestone under the U.S. Department of Energy’s Reactor Pilot Program. It is also the first DOE-authorized reactor built outside a national laboratory.
Ward 250 Completes Criticality Demonstration in Utah
The Utah San Rafael Energy Lab in Emery County is not a household name—but on June 18, 2026, it became the site of a significant moment in U.S. nuclear history. Valar Atomics’ Ward 250 reactor completed a zero-power fueled criticality demonstration there, earning recognition from the U.S. Department of Energy under its Reactor Pilot Program.
The DOE framed the event as part of what it calls America’s nuclear renaissance. Energy Secretary Chris Wright issued a statement marking the occasion and referenced an earlier milestone: Valar Atomics’ reactor had previously been airlifted aboard a U.S. military C-17 aircraft—an unusual logistical feat Wright cited as evidence of the company’s record of delivering historic achievements in advanced nuclear.
What sets Ward 250 apart is its location. It is the first DOE-authorized reactor built and operated outside a national laboratory, separating it from the controlled environments where experimental reactors have historically been developed and tested.
Why Criticality Matters and How Ward 250 Got There
Achieving criticality is not the finish line—it is the starting gate. It means a reactor can sustain a controlled nuclear chain reaction on its own, and without crossing that threshold, no electricity can be generated. A zero-power criticality demonstration confirms that the fundamental physics of a design work as intended.
Reaching that point required building an entirely new facility. According to Valar Atomics CEO Isaiah Taylor, the Utah San Rafael Energy Lab was constructed from scratch in roughly nine months. “Nine months ago, this was an empty site,” Taylor said. “Today, there’s a critical reactor on it, built and operated by the Valar team.”
That construction pace reflects how the DOE Reactor Pilot Program is structured—using DOE authorization to expedite certification and construction of first-of-a-kind advanced reactor designs, compressing a process that has traditionally taken years, sometimes decades.
Ward 250 Is the Second Reactor to Meet the July 4 Executive Order Deadline
The June 18 milestone did not occur in isolation. In May 2025, President Trump signed Executive Order 14301 setting a July 4, 2026 target for at least three advanced nuclear reactor concepts located outside of the national laboratories to achieve criticality. Ward 250 is the second reactor to meet that target.
Earlier in June, Antares Nuclear’s Mark-0 reactor achieved criticality at Idaho National Laboratory—the first to clear the bar. Ward 250 followed shortly after. The DOE has indicated that additional reactors are expected to reach the same milestone before the July 4 deadline passes, and back-to-back achievements suggest the program is delivering results at the pace its architects intended.
DOE Expands Nuclear Infrastructure With Nuclear Energy Launch Pad
Building on what the department describes as the program’s success, the DOE recently established the Nuclear Energy Launch Pad—a new initiative aimed at accelerating the deployment of advanced nuclear technologies beyond the demonstration phase. The Reactor Pilot Program’s momentum, it seems, has not gone unnoticed internally.
The program is specifically designed to extend and expand on the pilot program, opening the framework to fuel enrichment and reprocessing technologies while focusing on scaling technologies toward commercial deployment. By leveraging DOE authorization, companies like Valar Atomics can move from concept to operating reactor without navigating the full commercial licensing process from the outset—a meaningful advantage for organizations working at speed.
The Ward 250 project also involved collaboration with the State of Utah and Emery County, a partnership Taylor acknowledged directly. That local dimension carries real weight as advanced nuclear projects seek sites outside the traditional footprint of national laboratories.
As for what comes next, Taylor was direct: “This reactor was built to make power, and that’s exactly where we’re headed.” The criticality demonstration confirms the reactor can sustain a chain reaction. Converting that capability into actual electricity generation is the next phase—and the practical outcome the entire program is ultimately working toward.
Kelly is an experienced writer with 15 years of experience exploring the big stories that shape our world, from tech breakthroughs and space exploration to climate, energy, and the fascinating quirks of science. She has a talent for turning complex ideas into sharp, memorable insights that stay with readers long after they’ve finished reading.
