Optimization of sintering conditions of advanced tritium breeder pebbles fabricated by the emulsion method

Abstract

Demonstration power plant (DEMO) reactors require advanced tritium breeders with high thermal stability. Li2TiO3 with excess Li (Li2+xTiO3+y) has been developed as a material for an advanced tritium breeder. Considering the tritium release characteristics and the packing factor of the blanket, the optimum pebble diameter and grain size after sintering were determined to be 1mm and <5μm, respectively. Therefore, optimum sintering conditions were surveyed in the present study to obtain these target values. The predominant factor affecting grain growth is assumed to be the presence of binder in the gel particles. This remaining binder reacts with the excess Li in the Li2+xTiO3+y and Li2CO3 is generated, which promotes grain growth. To inhibit the generation of Li2CO3, calcined Li2+xTiO3+y pebbles were sintered under vacuum and subsequent 1% H2–He atmosphere conditions. The diameter of the sintered Li2+xTiO3+y pebbles was 1.07mm, and the average grain size on the surfaces and cross sections was <5μm. The results presented show that Li2+xTiO3+y pebbles with optimum characteristics were successfully fabricated using the emulsion method.