By Aidan Mortensen, KOAL News
This article is published through the Utah News Collaborative, a partnership of news organizations in Utah that aims to inform readers across the state.
A historic milestone was reached in Emery County Thursday afternoon, as Valar Atomics’ Ward 250 reactor completed a zero-power fueled criticality demonstration. The experiment marks the second criticality for Valar and the first nationwide for a Department of Energy-authorized reactor outside a national lab.
Despite the intimidating name, criticality in a nuclear reactor means that it can produce an ongoing, stable chain reaction. According to the Nuclear Regulatory Commission, this occurs when “each fission event releases a sufficient number of neutrons to sustain an ongoing series of reactions.” This reaction is what leads to power generation for the reactor.
“Moments ago, Valar Atomics took Ward 250 critical for the first time. This fulfills President Trump’s EO 14301, which called for 3 advanced reactors to go critical by July 4th,” said Valar CEO Isiah Taylor in a social media post. “This is a historic moment and the culmination of two years of work on the part of the Valar Atomics team. [These are] the most hardcore, intelligent, and driven people I’ve ever had the privilege of working with; which will be seen as we begin power ascension in the coming days.”
The Ward 250 project – which was first announced in May of 2025 – was a part of President Donald Trump’s executive order pushing to turn on an advanced nuclear reactor on American Soil by July 4, 2026, the country’s 250th birthday.
“Today marks another historic moment for America’s nuclear renaissance,” said U.S. Energy Secretary Chris Wright. “From the first-ever airlift of a small reactor aboard a U.S. military C-17 to successful zero-power criticality testing, Valar Atomics is delivering achievements that mark a revolutionary moment for advanced nuclear in this country. The Trump administration is proud to support the rebirth of America’s nuclear industry, ensuring Americans have access to affordable, reliable and secure energy for generations to come.”
The criticality of Ward 250 comes just weeks after Antares Nuclear’s Mark-0 reactor reached the milestone at the Idaho National Laboratory.
“This achievement is a testament to the innovators, builders, and public servants working to strengthen America’s energy future,” said Gov. Spencer Cox. “Utah is proud to be at the forefront of the next generation of nuclear technology.”
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