Non-Helium Cold Spray System for Nuclear Component Repair and Retrofit

While nuclear energy offers a number of advantages over conventional energy plants, including lower-cost operations and reduced carbon emission; to meet global energy needs and reduce nuclear power plant forced outages, cost effective methods of maintaining current reactors and efficient methods of building new reactors will be needed. Cold Spray (CS) is a solid-state deposition method that has been investigated in several applications in the nuclear sector. CS systems typically require expensive helium carrier gas to achieve the required particle deposition velocity for high-performance, dense deposits, that have lower than 1% porosityi. To reduce costs, improve efficiency, and extend operational lifetime, VRC Metal Systems, LLC, (VRC) proposes non-helium, high-pressure CS system for deposition of suitable materials for production, repair, and retrofit of nuclear reactor components. Hydrogen has similar gas dynamic properties to helium and analytical models based on the work of Champagne and Helfritch, et. al.ii show higher velocity capabilities using hydrogen due to the low molecular weight and high sonic velocity. Hydrogen is also significantly cheaper than helium, roughly 2.5x less based on purchasing in compressed bottled form and is not subject to availability issues. Phase 1 used a protype hydrogen system to successfully spray nickel and Inconel625 deposits in comparison to helium deposits at the same conditions. The hydrogen system builds off existing CS system designs, incorporating an enclosed environment and ventilation to accommodate the process gas. The results showed the hydrogen gas deposited at higher rates and produced higher quality deposits compared to helium at the same setpoints. This corresponds with calculations that hydrogen can achieve velocities equal or greater than helium without heat, further illustrating the potential of hydrogen as a viable gas for safely producing high quality cold spray deposits. The primary groups benefiting from the proposed work are the US Department of Energy (DoE) and nuclear energy companies. However, a deposition method capable of coating large components at low costs will be viable in many other industries including renewable energy, conventional energy, automotive, aerospace, and many other industries.