Plating Investigation for Aluminum Tritium Scroll Vacuum Pump to Improve Durability and Decrease Overall Cost

For handling radiated gases between the tritium (T) evacuation systems and the magnetic fusion chamber, scroll pumps have been the institutionally preferred solution because of their lack of any polymer seals, eliminating the possibility of contamination, all-metal stainless-steel design, impermeable by the radioactive T, and double bellows containment that provided redundant safety precautions. However, fusion research and development is still limited by steep production costs, long-lead times, and the difficulty of machining scroll vacuum pumps from stainless-steel. Stainless-steel is universally recognized as the only reliable means to contain radioactive T in fusion vacuum trains but little research has been conducted to evaluate the performance and permeability of alternative T handling materials that could significantly reduce capital cost, shorten development schedule, and simplify the adoption and commercialization of fusion reactor components. This SBIR proposes to conduct a T containment performance and permeability study to evaluate the effectiveness of T handling utilizing easily machined aluminum plated with nickel or other elements to replace state-of-the-art stainless-steel T containment. The project intends to show that alternative plated aluminum can maintain the same impermeability of stainless-steel throughout the expected lifetime of T handling components while maintaining or improving performance. Test coupons will be machined from aluminum and plated with various alternative tritium compatible materials and evaluated for their structural integrity over multiple thermal cycles and fatigue tests. Materials to be considered include but are not limited to nickel, gold, and silver. Using existing scroll hardware, each material will be measured for its resulting hardness, surface finish, thickness and build-up, and flatness after testing. In addition to the coupon samples that will be tested, Air Squared will plate two scrolls with the top two plating options for performance testing. Verifying inexpensive, easily machined materials can safely handle radioactive working fluids will appreciably lower economic cost barriers to entry for continued nuclear fusion research. Scroll vacuum pumps adapted with successfully evaluated materials after Phase II could be universally adopted and replace state-of-the-art stainless-steel pumps worldwide, at the 60 nuclear fusion research institutions.