WHY IT MATTERS: A privately built microreactor at Idaho National Laboratory has passed a key test, sustaining its own nuclear chain reaction and pushing a new generation of small reactors closer to real-world use. The Energy Department says Antares Nuclear's microreactor at the lab reached "criticality" on June 4. That milestone means the reactor can sustain a chain reaction that steadily releases energy, a basic requirement before it can generate power.
Federal officials cast the test as a win for the Trump administration's effort to speed up new nuclear projects. "We are very excited by this news today," Energy Secretary Chris Wright said during a call with reporters. "I think June 4th will be a historic day in the American nuclear renaissance." He added that Antares and its partners "have shown America can do bold things," crediting companies like Antares with advancing new reactor designs.
The Antares project is part of a federal pilot program launched last year under the Trump administration to speed up the development and testing of advanced reactors. Traditional nuclear plants are big, complex builds; microreactors are meant to be compact and movable. Federal agencies have already tested moving a small, unfueled reactor by air, underscoring interest in systems that can be deployed quickly to bases and other hard-to-reach sites.
