Manufacturing of the IFMIF HFTM double compartment prototype

Highlights: • Successful manufacturing of HFTM – shortcomings identified in regard of welding (large deflection). • Brazing and heat treatment of capsule material (P92) to change martensitic microstructure to austenite and carbide. • Important design improvements in "conclusion and improvements", derived from manufacturing (and operation −>not specified in paper). - Abstract: The High Flux Test Module (HFTM) of the International Fusion Materials Irradiation Facility (IFMIF) is a device to enable irradiation of Small Scale Testing Technique (SSTT) specimens by neutrons up to a structural damage of 50 displacements per atom (dpa) in an irradiation campaign of 1 year. The IFMIF source generates neutrons with a D-T-fusion-relevant energy spectrum and a flux to achieve a damage rate over 20 dpa per full power year (fpy) in a foreseen volume of 0.5 l. Irradiation temperatures are in the range of 250–550 °C. According to the IFMIF conditions and requirements, the IFMIF HFTM has been developed in the IFMIF/Engineering Validation and Engineering Design Activities (EVEDA) phase and a prototype was constructed and tested. The manufacturing process of relevant parts, like attachment adapter and container, is presented – especially with focus on problems in manufacturing accuracy. The capsule manufacturing process with focus on brazing process and finishing of the capsule shape is explained in detail. Optimization potentials derived from the manufacturing process and the experimental experiences are highlighted.