Westinghouse eVinci™ Microreactor Achieves Zero-Power Criticality

Achievement validates key design assumptions and advances Westinghouse's strategy for microreactor technology

CRANBERRY TOWNSHIP, Pa.--(BUSINESS WIRE)--Westinghouse Electric Company has successfully completed zero-power criticality testing for its eVinci™ microreactor, which validated the models and core design assumptions of the technology. The test was completed in partnership with Los Alamos and Idaho National Laboratories at the National Criticality Experiments Research Center (NCERC), a National Nuclear Security Administration (NNSA) facility at the Nevada National Security Site (NNSS), on August 24, 2026 at 10:39 a.m. PT.

This milestone is part of Westinghouse's rapid product development philosophy, which combines testing, modeling, simulation and design improvements to accelerate technology maturation while reducing technical risk. Through integrated prototype testing and demonstrations, Westinghouse will further validate the performance, operability and manufacturability of the eVinci technology. Learnings from each phase will help guide future development, design and prototype improvements.

“This zero-power criticality milestone reflects Westinghouse’s heritage of innovation and pushing to the next frontier of nuclear,” said Dr. Lou Martinez Sancho, Westinghouse Chief Technology Officer. “We appreciate the support and collaboration of our partners at the U.S. Department of Energy, NNSA, Los Alamos National Laboratory, Idaho National Laboratory and NNSS in achieving this important milestone.”

The eVinci microreactor combines advanced heat pipe technology, TRISO fuel, graphite core materials, control drum components and a compact architecture designed to provide resilient energy in remote and challenging environments, such as defense applications and space. The simple design builds on decades of industry-leading Westinghouse innovation to provide resilient electricity 24 hours a day, 7 days a week for eight years without refueling.

Westinghouse Electric Company is the future of energy, providing reliable, innovative nuclear technologies and services globally. Westinghouse pioneered commercial nuclear power, delivering the world’s first commercial pressurized water reactor in 1957. The company has industrialized more nuclear reactors than any other company, with its technology forming the basis of half of the world's operating nuclear plants. More than 140 years of innovation makes Westinghouse the preferred partner for advanced technologies covering the complete nuclear energy life cycle. For more information, visit www.westinghousenuclear.com and follow us on Facebook, LinkedIn and X.