Development of fabrication technologies for advanced tritium breeder pebbles by the sol–gel method

Demonstration power plant (DEMO) reactors require advanced tritium breeders with high thermal stability. Li2TiO3 with excess Li (Li2+xTiO3+y) was developed as an advanced tritium breeder. Pebble fabrication by the sol–gel method is a promising technique for the mass production of advanced tritium breeder pebbles. I have been developing a sol–gel technique for fabricating Li2+xTiO3+y pebbles, and the next step is to optimize the granulation conditions to reach the target value. In a previous study, the average grain size on the surfaces and cross sections of sintered Li2+xTiO3+y pebbles was large whereas the theoretical density (T.D.) of these pebbles was small. To increase the density of the sintered Li2+xTiO3+y pebbles, the sintering temperature was changed, and at 1353 K, the density of the pebbles increased to approximately 85% T.D. without any increase in the grain size. This suggests that the pore size in the sintered Li2+xTiO3+y pebbles decreased because of sintering in vacuum and argon.