Antares today announced that its Mark-0 microreactor achieved initial criticality at Idaho National Laboratory (INL) under U.S. Department of Energy (DOE) authorization — making Antares the first private company to bring an advanced reactor to criticality under the DOE Reactor Pilot Program. The demonstration was conducted in partnership with DOE, INL, and BWX Technologies, with integration and observation support from the U.S. Army. “Today’s achievement is a historic moment for American nuclear energy,” said U.S. Energy Secretary Chris Wright. “By bringing the first American non-light water privately developed reactor to criticality in more than four decades, Antares has shown what is possible when American innovation is unleashed. The Trump administration is proud to support the rebirth of America’s nuclear industry and ensuring Americans have access to affordable, reliable and secure energy for generations to come.” The demonstration meets an ambitious objective set by the President and DOE to reform how the federal government tests advanced reactors, and it establishes a replicable licensing pathway that DOE and industry can use to accelerate future reactor demonstrations on commercial timelines.

“Hitting our commitments is everything to us. Nuclear in America has been defined for too long by delays, by companies that said they would and then didn’t,” said Jordan Bramble, CEO of Antares. “We said criticality in 2026, electricity production in 2027, and power to the warfighter in 2028. Today is the first of those commitments delivered on the schedule we set. The President and DOE set an ambitious timeline for reactor testing, and we met that challenge. I want to thank our partners at the Department of Energy, Idaho National Lab, BWXT, and the U.S. Army. This is what happens when industry and government work together to accomplish big things.”

Full report : Antares Industries’ Mark‑0 is the first of several advanced reactors targeting criticality by the 4 July deadline set in President Trump’s May 2025 Executive Order.

For more see the OODA Company Profile on Antares Industries.