Behaviour of Li2ZrO3 and Li2TiO3 pebbles relevant to their utilization as ceramic breeder for the HCPB blanket

Li2ZrO3 and Li2TiO3 pebbles are being investigated at Commissariat à lʹEnergie Atomique as candidate alternative ceramics for the European helium-cooled pebble bed (HCPB) blanket. The pebbles are fabricated using the extrusion–spheronization–sintering process and are optimized regarding composition, geometrical characteristics, microstructural characteristics, and material purity. Tests were designed and are being performed with other organizations so as to check the functional performance of the pebbles and pebble beds with respect to the HCPB blanket requirements, and, finally, to make the selection of the most appropriate ceramic for the HCPB blanket. Tests include high temperature long-term annealing, thermal shock, thermal cycling, thermal mechanical behaviour of pebble beds, thermal conductivity of pebble beds, and tritium extraction. Current results indicate the attractiveness of these ceramics pebbles for the HCPB blanket.