A privately built nuclear reactor went critical at Idaho National Laboratory on Thursday. It was the first time a private company has pulled that off in the United States in more than 40 years. The last time anything like this happened, Ronald Reagan was in his first term, and the Soviet Union still existed.
The reactor belongs to Antares Nuclear, which says it has raised more than $140 million in private funding. It is not yet generating electricity, but Antares has committed to producing power from the same Idaho facility by 2027. The reactor test took place ahead of a July 4 deadline that President Trump set by executive order.
Energy Secretary Chris Wright noted the historical importance of the moment:
“For the first time in more than four decades, a new privately developed non-light-water reactor has reached criticality in the United States. Thank you to President Trump for his bold leadership and thank you to the bold scientists and entrepreneurs at Antares and Idaho National Laboratory who helped make this moment possible. I look forward to seeing continued progress in the American nuclear renaissance.”
Antares CEO Jordan Bramble expressed his team’s commitment to the goal:
“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. 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 company went from concept to a working reactor in under 12 months. Bramble credited the Reactor Pilot Program’s structure and decades of prior DOE investment in the fuel and manufacturing infrastructure behind it.