Electrochemical Repair of Surface Damage for Tungsten Plasma Facing Components

During tokamak fusion reactor operation, extreme thermal loads erode the tungsten armor of plasma facing components and remotely operated maintenance technologies are required to address this damage. The most advanced maintenance strategy uses remote handling systems to remove and replace entire reactor plasma facing components (not just the damaged tungsten armor), a process which is projected to take anywhere from 70 days to 8 months). Alternative technologies which decrease the cost or duration of reactor maintenance would increase the economic competitiveness of future fusion reactors. General statement of how this problem is being addressed. A repair tool/process is being developed for tungsten plasma facing components. The repair process works by removing the damaged surface layer and depositing a layer of undamaged material. The repair tool will be integrated with remote handling systems to enable in-field repair during reactor maintenance periods. In Phase I, the technical feasibility of the repair process was validated using virgin tungsten by demonstrating the ability to remove and re-apply over 100 microns of tungsten. This 100-micron target was chosen because it is the anticipated crack depth induced by fusion-relevant heat loads. A repair tool prototype was designed with the size requirements needed for in-field repair. A technology development roadmap was prepared that identified a pathway for integration of this repair technology in a first-of-a-kind fusion pilot plant by the mid-2030s. What is planned for the Phase II project? In Phase II, the repair process will be validated using tungsten damaged under fusion-relevant thermal loads. High heat flux and vacuum compatibility testing will be conducted to demonstrate the robustness of the repaired tungsten under fusion-relevant conditions. The repair tool prototype designed during Phase I will be constructed and validated at temperatures (230 °C) and vacuum pressures anticipated during fusion reactor maintenance periods. These activities will pave the way for a remote handling demonstration during Phase III. Commercial Applications and Other Benefits (limited to the space provided).. The robot-operated repair process/tool has the potential to benefit any industries where repair work is required in hazardous environments. Potential industrial sectors include fusion, space, petrochemical, and nuclear fission.