Trump's 2025 executive order called for 3 reactors to be critical in time for the 250th anniversary of the USA.

The start-up Valar Atomics has taken its WARD 250 test reactor critical at the Utah San Rafael Energy Lab (USREL), becoming the second company in the Department of Energy's Reactor Pilot Program to reach the milestone, and, according to the DOE, the first to do so outside a national laboratory.

The announcement came on June 18, when the milestone was specifically the reaching of a zero-power fueled criticality. "Criticality" demonstrates that the reactor sustains a controlled nuclear chain reaction and is the first step towards actually generating power.

Since then, Valar has been gradually proceeding with a planned power ascension. By June 22 it announced that the output had reached 10 kWt.

This is one tenth of the 100 kWt power output intended as the first major testing target for this TRISO-fueled high-temperature gas reactor. The reactor will have a thermal peak power of 250 kWt, with its design then being gradually stepped up towards the full design architecture of 5 MWe.

Valar Atomics had already achieved criticality, but with an experimental core, at the Los Alamos National Laboratory back in November 2025.

The WARD 250 reactor is the first to achieve criticality outside national laboratories and is fully intended to go on to generate power. The USREL site, just outside Orangeville, Utah, is operated by the state under the Office of Energy Development.

The WARD 250 made the news in February when it was airlifted, broken down into its 8 primary modules, by USAF C-17s from March Air Reserve Base in California to Hill AFB in Utah, in what was the first air transportation of its kind. The complex operation was baptized WINDLORD.

From Hill, the WARD 250 was then moved by road to its current position within USREL.

Another company, Antares Nuclear, also achieved criticality this month with its Mark 0 reactor, in this case at the Idaho National Laboratory.

These achievements come as the deadline of July 4, set by President Trump's May 2025 executive order, draws near: Trump requested the Department of Energy to bring "multiple" new, advanced reactors to critical state in time for the 250th anniversary of the United States of America.

To meet the stated target of 3 reactors going critical, one more system is to achieve the milestone within days. The candidates with a chance to do so belong to the companies Aalo, Radiant and Deployable Energy, who are in the process of clearing their respective reactors through DOE safety analysis.

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