A critical review on advanced welding technologies to fabricate test blanket modules and irradiation damage behaviour of the welded joints in nuclear fusion applications

Abstract

Nuclear fusion is heralded as the ultimate energy source for the future of humanity. Test blanket module (TBM) is one of the critical components in International Thermonuclear Experimental Reactor (ITER) to regenerate enough tritium to keep fusion reactions going in a steady and self-sufficient mode. Reduced activation ferritic/martensitic (RAFM) steels and austenitic stainless steels are widely employed in the fabrication of TBM structure components. Welding technology is crucially important for TBM manufacturing due to the large size and high complexity. As the most vulnerable part of the component, the welded joints are prone to fracture earlier than the base materials in extreme service environments. In this context, this review systematically examines the development of RAFM and austenitic stainless steels used for nuclear fusion worldwide and their irradiation damage mechanisms. Furthermore, this review highlights the welding technologies for structural materials, discussing the effects of heat treatment and irradiation on the microstructure and mechanical properties evolution of the welded joints. Additionally, the urgency of developing specific filler materials and systematically studying the irradiation damage behaviour of RAFM/316LN dissimilar steels welded joints are emphasized. Finally, the review concludes by discussing recent advancements and further development trends in TBM's fabrication. The review could provide theoretical foundations for the fabrication of high-performance TBMs and data support for the safe operation of nuclear fusion reactors.