Shigeru Saito

Density dependence on thermal properties of Li2TiO3 pellets

Lithium ceramics have been considered as tritium breeders for fusion reactors. As a part of the study program for fusion blanket development, the characteristics of tritium breeders are estimated for the material selection and fusion blanket design. Among the candidate tritium breeders, lithium titanate (Li 2 TiO 3 ) is regarded as one of the best materials because of many advantages, reasonable lithium atom density, low activation, excellent tritium release characteristic at low temperature, compatibility with structural materials, reprocessing, etc. However, only limited data on the thermal and mechanical characteristics of Li 2 TiO 3 have been obtained for breeder material selection and fusion blanket design. In this study, Li 2 TiO 3 pellets with three different densities, i.e., 73%T.D., 83%T.D. and 93%T.D., were prepared. Then, the density dependence and the thermal hysteresis of their thermal conductivity, specific heat and thermal expansion were investigated.

Fabrication development of Li2O pebbles by wet process

Lithium oxide (Li 2 O) is one of the best tritium breeding materials. A small sphere of Li 2 O is proposed in some designs of fusion blankets, Recently, reprocessing technology on irradiated ceramic tritium breeders was developed from the viewpoint of effective use of resources and reduction of radioactive wastes, The wet process is advantageous for fabricating small Li 2 O pebbles from the reprocessed lithium-bearing solutions. Preliminary fabrication tests of Li 2 O pebbles by the wet process were carried out. However, the density of the pebbles obtained was only 55%. Therefore, process improvement tests were performed in order to increase the density of Li 2 O pebbles fabricated by this method. The improved process yielded Li 2 O pebbles in the target range of 80-85% T.D.