Deuterium retention properties and bubble behaviors of Be12Ti after irradiation with D+ at high temperature

In the Japanese demonstration (JA DEMO) fusion reactor, Be₁₂Ti blocks as a neutron multiplying material and Li₂TiO₃ pebbles as a breeding material will be planned to set in the blanket. When the replacement of the blanket due to the life of the structure materials, tritium generation with 200 appm T in Be₁₂Ti blocks can be anticipated. The Be₁₂Ti blocks containing tritium may cause several problematic issues in JA DEMO. The objective of this study aimed to evaluate the correlation between deuterium (D) retention properties and the bubble behaviors in Be₁₂Ti.

We investigated the D retention properties in the Be₁₂Ti samples, which were irradiated with D⁺ ions at R.T.-873 K using thermal desorption spectroscopy. The bubble behaviors in the thin Be₁₂Ti samples were observed under annealing using in-situ transmission electron microscope (TEM). And the Be samples were prepared to be comparable with Be₁₂Ti and done similarly to the same experiment.

The D desorption peaks were confirmed from the mechanical-polished and electropolished Be₁₂Ti samples after irradiation with D⁺ at R.T. and high temperature. For both mechanical-polished and electropolished Be₁₂Ti samples, the desorption peak shifted to higher temperatures with increasing irradiation temperatures. In-situ TEM observed the bubble behaviors, and Most of the bubbles wouldn’t change in thin Be₁₂Ti samples after irradiation with D⁺ at R.T. and 673 K during annealing (∼1073 K). These results indicate that no correlation between the deuterium releases and the bubble behavior in Be₁₂Ti until 1073 K.