Effects of helium production and radiation damage on tritium release behavior of neutron-irradiated beryllium pebbles

The tritium release from neutron-irradiated beryllium pebbles, irradiated under different helium production (0.5–1.0 × 103 appm He) and dpa (4.2–8.6) conditions, was studied. From these results, it was clear that the apparent diffusion coefficient at 600°C was significantly affected by irradiation conditions, but returned to normal values at 900°C, apparently due to thermal annealing. Multiple peaks in the tritium release curve at 900°C were observed.