Long‐term thermal stability of Li₄TiO₄–Li₂TiO₃ core–shell breeding pebbles under continuous heating in H₂/Ar atmosphere

Abstract

The long‐term thermal stability of tritium breeding materials during service is a key factor to ensure efficient tritium release. In this study, the long‐term thermal stability of advanced Li4TiO4–Li2TiO3 core–shell breeding pebbles under continuous heating in 1%H2/Ar at 900°C was investigated for the first time. The results show that this core–shell material loses 3.4% Li mass after heating for 30 days, resulting in a reduction in Li density to .415 g/cm3, which is still significantly higher than other breeding materials. The moisture in the sample bed will determine the form of Li volatilization and thus affect the rate of Li mass loss. The core–shell pebbles maintain favorable phase stability during long‐term heating, and the grain sizes of the Li2TO3 shell and Li4TiO4 core after 30 days of heating are 6.5 ± 1.5 and 6.9 ± 2.5 μm, respectively. Moreover, the samples did not crack or collapse during long‐term heating and still had a satisfactory crushing strength of 37.61 ± 7.13 N after 30 days of heating. Overall, the high Li density and good thermal stability during long‐term heating demonstrate that the Li4TiO4–Li2TiO3 core–shell breeding pebbles are a very reliable tritium breeding material for long‐term service under harsh operating conditions.