The emerging technology of advanced nuclear microreactors offers solutions to many modern energy challenges. The ZiaCore design, a low-enriched uranium dioxide-fueled microreactor developed by Los Alamos National Laboratory, now joins several developing concepts for fission-based nuclear power microreactors that have achieved initial criticality. The ZiaCore design reached this milestone through a proof-of-principle experiment—a high-temperature, zero-power criticality demonstration at the National Criticality Experiments Research Center (NCERC) in Nevada.

“The execution of our ZiaCore experiment will support an entire category of nuclear power microreactors,” said Christopher Stanek, director of the Nuclear Energy Program Office at Los Alamos. “The experiment will provide valuable data for low-enriched reactor technologies, including components developed at Los Alamos, at representative reactor temperatures.”

Over four weeks in April and May this year, the ZiaCore system was brought to zero-power criticality at high temperatures. An important benchmark in reactor design and testing, zero-power criticality provides invaluable validation of reactor physics—essentially proving that the reactor design is valid.