Welding and Joining Technologies for Manufacturing of Small Modular Reactors (SMRs): A Review on Processes and Joint Integrity

Small modular reactors (SMRs) are emerging as next-generation nuclear systems driven by enhanced safety, modular design, and factory-based manufacturing. These changes require advanced fabrication strategies, where welding and joining technologies play a critical role in ensuring structural integrity and production efficiency. This paper reviews welding and joining technologies for SMR manufacturing, focusing on process characteristics and joint integrity. Key components such as pressure vessels, heat exchangers, and piping systems are examined, and both conventional processes (GTAW, GMAW) and advanced techniques (laser beam welding, electron beam welding, friction stir welding, and narrow gap welding) are discussed in terms of their applicability. The integrity of welded structures is analyzed with respect to defect formation, residual stress, creep, fatigue, and fracture behavior, along with the application of non-destructive evaluation techniques. In addition, emerging manufacturing approaches such as PM-HIP are introduced as complementary technologies that reduce welding requirements while introducing new interface-related challenges.