Tritium desorption and tritium removal from tungsten pre-irradiated with helium

•Helium pre-irradiation effects on tritium desorption/retention in tungsten was investigated.•Tritium in helium-irradiated tungsten was desorbed at higher temperatures.•Long term tritium release was significantly delayed in helium irradiated tungsten.•Helium effects on tritium desorption/retention depended on pre-irradiated helium fluence.

In this study, 1 keV DT+ ion irradiation was performed on tungsten pre-irradiated with helium. The thermal desorption behavior and the reduction of tritium retention during vacuum preservation at room temperature, as well as isochronal annealing were investigated using an IP technique, taking advantage of the fact that tritium detection is nondestructive and is highly sensitive. At a pre-irradiated helium fluence of 1 × 1017 He/cm2, retained tritium tended to be desorbed at higher temperatures when compared to no helium irradiation case. Tritium retention during preservation in vacuum and during isochronal annealing became smaller with increasing helium fluence up to 1 × 1017 He/cm2. At a helium fluence of 1 × 1018 He/cm2, the reduction of tritium retention was found to be greater compared to 1 × 1017 He/cm2. The results indicate that helium irradiation has a significant influence not only on the thermal desorption temperature of tritium but on longtime tritium reduction at room and elevated temperatures.