ESR Study on Annihilation Process of Radiation Defects Induced in Solid Tritium Breeding Materials by Neutron Irradiation

Annihilation processes of radiation defects induced in solid-tritium breeding materials by neutron irradiation were studied by ESR measurement. The ESR spectrum for neutron-irradiated Li2TiO3 is asymmetric, hence it is consists of several signals. This means that there are some para-magnetic radiation defects. The results of the annealing experiments indicate that there are two annihilation processes of the radiation defects, the fast one and the slow one, and the activation energies (Ea) of these are 0.413 and 0.408 eV, respectively. Then, it is suggested that the fast one would concern lithium ion diffusion, and the slow one oxygen. A comparison between the annihilation processes and the tritium release processes results in that the slow process and the tritium release from the bulk take place simultaneously. Hence, the oxygen diffusivity in each sample could play an important role in tritium release processes.