09/18/2026
THE HEAT IS ON: Westinghouse Electric Company just reached a key milestone for its eVinci microreactor. The advanced reactor prototype completed criticality testing earlier this month, reaching core temperatures upwards of 1,000°C as the company gathered valuable data on its performance.
The transportable, heat-pipe-cooled reactor design runs on TRISO fuel and is designed to produce 5 megawatts of electricity on sites as small as two acres of land, providing resilient 24/7 energy for 8+ years without refueling.
Criticality testing was conducted at the National Criticality Experiments Research Center (NCERC), a National Nuclear Security Administration facility at the Nevada National Security Site. Partners on the project included Los Alamos National Laboratory, Idaho National Laboratory and the DOE/NRC Collaboration for Criticality Safety Support for Commercial-Scale HALEU Fuel Cycles and Transportation.
Data gathered from these experiments will help Westinghouse refine its design and increase certainty around the cost, manufacturability and schedule for eVinci, which was selected in August 2026 for the next phase of the Janus Program — the U.S. Department of the Army’s next-generation nuclear power initiative to power U.S. military installations with microreactors.
