Research status and future outlook of dissimilar metal welding for nuclear power nozzle-to-safe-end joints

The nozzle-to-safe-end joint of nuclear power equipment is a key welded structure in the primary circuit of nuclear power plants. It is usually formed by welding dissimilar metals of low-alloy high-strength steel and stainless steel using nickel-based alloy or stainless steel welding materials. Due to its long-term exposure to intense neutron irradiation and high-temperature and high-pressure water corrosion environments, more stringent requirements are imposed on its thermal stability, mechanical properties, interfacial connection reliability, and overall service life. At present, how to achieve high-quality welding of nozzle-to-safe-end joints remains a research focus and difficulty in China and internationally. Therefore, based on Chinese and international literature, the research status of dissimilar metal welding for nozzle-to-safe-end joints was systematically reviewed from four aspects: metallurgical issues, compatible welding materials, welding methods, and joint reliability. Furthermore, future research directions requiring in-depth study were discussed to provide a reference for subsequent studies on improving the quality and reliability of such joints.