Ion conductivity of lithium oxide (Li2O) irradiated with oxygen ions was measured to obtain information about the effects of irradiation on the behavior of lithium ions and tritium. The conductivity around 490 K decreased with the ion fluence, while around 440 K it increased. The decrease around 490 K and the increase around 440 K were assumed to be attributed to the F+ centers and the unspecified radiation defects, respectively. From the point of view that the rate determinant in the mechanism of diffusion of lithium ions in Li2O leading to the ion conductivity is the same as that of tritium, the diffusivity of tritium is assumed to be as follows: the diffusivity of tritium is decreased by the F+ centers in the range from 490 K to the temperature at which almost all of F+ centers are recovered, while it is increased around 440 K by the unspecified radiation defects. In addition, effects of the irradiation on valence states of tritium (i.e., T+, T−) were discussed in terms of the radiation defects.
In-situ tritium release experiments from solid breeding materials (TTTEx) — Released chemical form of tritium and its diffusivitees in Li2O