New method checks heat exchanger strength for safer nuclear reactors

Engineers at the University of Wisconsin-Madison have developed a new inspection method aimed at accelerating the adoption of compact heat exchangers in advanced nuclear reactors. These heat exchangers, crucial for transferring heat efficiently under extreme temperatures and pressures, rely on diffusion welding to bond thin metal plates into a solid structure. A major challenge has been verifying the structural integrity of these internal welds over time, as weakening bonds can compromise reactor safety and efficiency. The new method uses automated image analysis to measure microscopic grain growth across weld interfaces, providing a reliable metric for bond strength. Focusing on materials already approved for nuclear use—stainless steel 316H and alloy 617—the research team collaborated with industry partners to produce sample components and analyze them microscopically. By quantifying grain growth, which correlates directly with bond quality, the method offers a repeatable and measurable standard that could inform future industry guidelines, such as those from the American Society of Mechanical Engineers. This advancement promises to enhance confidence in compact heat