As part of the U.S. Department of Energy (DOE) Reactor Pilot Program, Antares Nuclear’s advanced reactor design, the Mark-0, successfully completed a zero-power fueled criticality demonstration at DOE's Idaho National Laboratory, the DOE reported on June 4.
This test confirms that the reactor can operate safely and establishes a basis that would allow subsequent reactors to produce electricity in 2027 and beyond.
The Mark-0 is the first of multiple advanced reactors anticipated to go critical by the July 4th deadline set by President Trump in his May 2025 executive order, DOE said.
“For the first time in more than four decades, a new privately developed non-light-water reactor has reached criticality in the United States," said U.S. Energy Secretary Chris Wright.
Criticality is the culmination of carefully planned and executed steps that result in a reactor going operational, DOE noted.
The Mark-0 criticality test "is a tremendous accomplishment that validates the safety and operational performance of Antares Nuclear’s fission reactor. One of the most significant technological achievements in nuclear energy in over 40 years, this test will go on to inform the design and licensing of future commercial reactor deployments," DOE said.
When commercialized after further tests and licensure by the Nuclear Regulatory Commission, microreactors like those that Antares makes are expected to be used in a variety of terrestrial and space applications and to ensure readiness at military installations requiring reliable energy.
"As the 53rd reactor to be built at Idaho National Laboratory site since 1951, Mark-0 joins the storied ranks of test reactors that served as the blueprint for our nation’s current reactor fleet," DOE said.
The Reactor Pilot Program leverages DOE authorization to expeditiously certify and construct first-of-a-kind advanced reactor designs for demonstration.
Building on the Reactor Pilot Program’s success, DOE recently established the Nuclear Energy Launch Pad to further accelerate the deployment of advanced nuclear technologies.
For additional information about Antares, go to its website.
