European test blanket modules: An overview of fabrication technologies development and EUROFER97 steel supply

Abstract

Two tritium breeding blanket concepts, the Water-Cooled Lithium-Lead (WCLL) and the Helium-Cooled Ceramic Pebble (HCCP), are under development in Europe for testing in ITER as Test Blanket Modules (TBMs). Both concepts employ EUROFER97 reduced-activation ferritic-martensitic (RAFM) steel as the structural material. This paper provides an overview of R&D activities focused on the manufacturing and assembly of key TBM structural components, including: (i) subcomponents with embedded cooling channels (First Wall, Side Caps, Stiffening Plates, and Cooling Plates); (ii) the TBM box, comprising the First Wall and two Side Caps; (iii) the TBM box structure, integrating the TBM box with horizontal and vertical Stiffening Plates; and (iv) the TBM manifold area, incorporating multiple back plates and through-penetrating components. The reported activities assess the feasibility of the selected manufacturing routes for EUROFER97 TBM components, combining fusion-based welding techniques (TIG, laser beam welding, and electron beam welding) with diffusion-based joining by hot isostatic pressing (HIP). In addition, the paper outlines the characteristics of the EUROFER97 steel used for both TBM design concepts and describes the future procurement strategy, which will be conducted according to a Particular Procurement Specification, as allowed by the RCC-MRx code, and following the EUROFER technical specification formalized currently in probationary phase. Within this framework, qualification and demonstration of the steel manufacturing process, including workshop qualification, are mandatory prerequisites to ensure the delivery of high-quality steel products.