Thermal and tritium transport in Li2O and Li2ZrO3

Lithium oxide (Li2O) and lithium zirconate (Li2ZrO3) are promising tritium breeder ceramics for fusion reactors. The thermal and tritium transport databases for these materials are reviewed. Algorithms are presented for predicting the temperature and retained-tritium profiles across sintered-product and pebble-bed regions. The thermal conductivity of sintered-product material has been measured and correlated over a wide range of temperatures and densities. A modified Hall and Martin model gives good agreement with data for the effective conductivity of pebble beds of these ceramics. Laboratory data for tritium behavior in Li2O have been used to determine model parameters in the TIARA code, which has been validated to 20 post-irradiation inventory data points. As the fundamental database for Li2ZrO3 is less complete, a residency-time correlation, based on 31 inventory data points, is proposed. The two ceramics are compared in the context of an ITER breeding-blanket design.