Development and qualification of functional materials for the European HCPB TBM

Highlights: • The LOS extensively characterized, including under neutron irradiation conditions. • Advanced CB pebbles with improved mechanical properties fabricated and characterized. • HICU PIE results provided very important information for CB material qualification. • The 1 mm Be pebbles are the reference multiplier material for HCPB blanket concept. • HIDOBE PIE results delivered crucial information for Be qualification and licensing. - Abstract: The paper reviews the current status of development and qualification of the HCPB TBM's functional materials, namely, Li-ceramic breeder and Be multiplier materials. The main functional and performance requirements for both functional materials are overviewed. The main results and outcomes of the post-irradiation examinations (PIE) of Li-ceramic breeder and Be/beryllides materials irradiated in HIDOBE and HICU irradiation campaigns are presented aiming at determination of the materials' performance, properties and characteristics under neutron irradiation, like e.g. morphology and microstructure, tritium retention/release characteristics, mechanical properties. Fabrication of the advanced ceramic breeder material, containing lithium orthosilicate with addition of lithium metatitanate phase in order to improve its mechanical properties, is described. Results of characterization of this advanced ceramic breeder in terms of mechanical properties, porosity, morphology and effective thermal conductivity of a pebble bed are overviewed. In addition, results of characterization of the reference 1 mm Be pebbles produced by Rotation Electrode Process are presented in terms of their microstructure, tritium release characteristics and interaction with air and steam. A necessity to realize in the future a new irradiation experiment for the functional materials, LIBERTI experiment, is discussed in the conclusions.