Westinghouse eVinci Microreactor Reaches Zero-Power Criticality Milestone

Westinghouse completed zero-power criticality testing of its eVinci microreactor on August 25 at the Nevada National Security Site. The test was conducted in partnership with Los Alamos and Idaho National Laboratories at the National Criticality Experiments Research Center, a National Nuclear Security Administration facility.

Zero-power criticality marks the point at which a nuclear reactor sustains a controlled, self-supporting chain reaction. Unlike full-power operation, this milestone validates core design assumptions and computational models without generating heat or electricity. The achievement demonstrates progress in Westinghouse's development pathway for the containerized microreactor system.

Technology Specifications

The eVinci is a heat pipe-cooled microreactor designed to produce up to 5 megawatts electric with a 15 megawatt thermal core. The reactor uses TRISO fuel and is engineered to operate for eight or more years at full power before requiring refueling.

The factory-built and assembled design enables containerized shipping, supporting deployment across diverse applications including defense and space missions. This modular approach addresses supply chain efficiency by consolidating manufacturing and reducing on-site assembly requirements.

Development Approach

Westinghouse characterized the criticality test as part of its rapid product development philosophy, which integrates testing, modeling, simulation, and iterative design refinement. The company stated this integrated approach accelerates technology maturation while reducing technical risk.

The milestone reflects collaboration with the U.S. Department of Energy and national laboratory partners. Westinghouse Chief Technology Officer Lou Martinez Sancho noted the achievement represents the company's commitment to advancing next-generation nuclear technology.

Inertia and LLNL Cut Fusion Target Fuel Production Time

Inertia Enterprises and Lawrence Livermore National Laboratory have jointly developed an accelerated manufacturing process for the deuterium-tritium ice layer used in inertial confinement fusion target capsules. The process compresses production time from multiple days to a matter of hours, according to Inertia.

The fuel layer—a thin cryogenically frozen coating of deuterium-tritium (D-T)—is a critical component in the spherical carbon-shell capsules used for fusion ignition. Achieving a sufficiently smooth ice layer is essential for target performance. The new process improves manufacturing efficiency while maintaining the surface quality required for ignition conditions.

Supply Chain and Operational Benefits

The manufacturing acceleration delivers multiple advantages across the fusion fuel supply chain. Reduced production time directly lowers manufacturing costs per target, improving economics for pilot-plant operations. The faster cycle also decreases the quantity of tritium that must be maintained in inventory at production facilities.

Lower tritium inventory requirements reduce material handling costs and associated regulatory compliance burdens. Tritium, a scarce and tightly controlled isotope, represents both a supply constraint and a regulatory liability. Minimizing on-site quantities eases operational complexity and reduces dependence on limited fuel supplies, strengthening supply security for fusion energy development.

Xudabao simulator commissioned ahead of operator training

A full-scope simulator for the Xudabao nuclear power plant was formally commissioned this week. The facility will support training for the initial cohort of operators assigned to units 1 and 2 before those reactors begin commercial operation. Officials described the milestone as foundational to establishing qualified personnel and maintaining safety standards during the transition to active plant operation.

Project scope and reactor technology

Xudabao units 1 and 2 are each equipped with 1250 MWe CAP1000 reactors, a Chinese-designed pressurized water reactor based on Westinghouse technology. Construction licences for both units were issued in November 2023, with formal site work commencing that same month near Xingcheng City in Liaoning Province. The combined investment in the first two units exceeds CNY48 billion, equivalent to approximately USD6.6 billion.

The broader Xudabao project originally envisioned six reactors at the site. Units 3 and 4, supplied as Russian-designed VVER-1200 reactors, entered construction in 2021 and 2022 respectively, with commissioning targeted for 2027 and 2028. Two additional CAP1000 units remain in the proposal phase. When fully developed, the six-unit complex is projected to generate more than 7.6 GW of installed capacity and supply approximately 54 billion kilowatt-hours annually.

Ownership and contracting

Liaoning Nuclear Power Company Ltd holds operational responsibility for the Xudabao site. The company is structured with a 70 percent stake held by China National Nuclear Corporation, 20 percent by Datang International Power Generation Company, and 10 percent by State Development and Investment Corporation. China Nuclear Power Engineering Company Ltd, a subsidiary of China National Nuclear Corporation, serves as the general contractor for construction activities.

Ongoing simulator operation, maintenance, and optimization will be managed by CNNC Wuhan Nuclear Power Operation Technology Co, the subsidiary that developed the facility. The simulator is expected to support continuous training and qualification of operating personnel through the commissioning phase and into routine operations.