Comparative assessment of RAFM steel first wall structural manufacturing technologies for fusion breeding blankets: From ITER TBM to DEMO

In fusion power plants, the Breeding Blanket (BB) enables heat extraction and tritium breeding, while its plasma-facing First Wall (FW) is among the most critical and challenging components to manufacture due to extreme operating loads it endures. During the past three decades, research has largely concentrated on developing robust manufacturing technologies for various DEMO and Test Blanket Module FW concepts, especially those utilizing Reduced Activation Ferritic Martensitic (RAFM) steels. Reported fabrication routes include conventional processes such as Electrical Discharge Machining (EDM) + Cold Forming and Hot Isostatic Pressing (HIP) as well as emerging additive and hybrid methods such as Selective Laser Melting (SLM) and Cold Spray deposition. This review aims to provide a comprehensive overview of the various FW manufacturing technologies. To assess the technological promise and practical applicability of these approaches for DEMO scale FW manufacturing, a comparative evaluation has been carried out using five key criteria: manufacturability, industrial scalability, production quality, cost-effectiveness, and its coverage in nuclear construction codes. Technology Readiness Levels (TRL) has also been indicated for these manufacturing routes. The evaluation indicates that conventional manufacturing routes for U-shaped FW configuration demonstrate higher maturity over recently emerging additive and hybrid techniques which is also indicated by relatively higher TRL of these technologies. For non-typical Japanese “O” Cylindrical blanket configuration, conventional forging-based FW manufacturing remains the most mature solution. However, its reliance on fusion welding introduces concerns regarding joint reliability. To address this, a novel modular Monoblock configuration recently developed at KIT has been presented.