Manufacturing of a representative DEMO divertor shielding liner mock-up by hot isostatic pressing

The DEMO divertor shielding liner is a critical structural component ensuring coolant confinement, heat removal, and neutron shielding under severe operating conditions. Its large dimensions and complex internal cooling geometry require the assembly of multiple sub-components using robust joining technologies. In this context, hot isostatic pressing combined with diffusion welding (HIP-DW) is a promising solution for consolidating large-area and inaccessible interfaces. This paper presents the development and demonstration of a manufacturing route for the DEMO divertor shielding liner based on a strip-type assembly concept combining vacuum laser welding and gas tungsten arc welding for sealing, followed by HIP diffusion bonding. A representative mock-up was designed to reproduce the key geometrical features and assembly interfaces of the DEMO reference design while remaining compatible with manufacturing and testing constraints, and was fabricated using Grade 91 ferritic–martensitic steel as a surrogate material. The complete manufacturing sequence was successfully demonstrated, and the assembled mock-up passed a hydraulic pressure test at 222 bar in accordance with the Pressure Equipment Directive, confirming leak-tightness and structural integrity. These results demonstrate the feasibility and robustness of the proposed manufacturing route and support its further development toward full-scale DEMO divertor shielding liner components.