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Sensitivity and uncertainty analyses of lead (Pb) isotope cross sections are conducted with the use of sample reactivity experiments at the Kyoto University Critical Assembly (KUCA). With the combi...

Retention of He and accumulation of H in the near surface layer of W and Mo single-crystals were studied during and after the implantation of He ions with 2–10 keV at 295 and 820 K. The He retention was saturated at a concentration of a He/metal ratio of about 0.25, depending on the implantation temperature. Subsequent He implantation caused H accumulation in the He saturated layer, up to a maximum concentration about equal to that of He. The initial H uptake rate just after the He irradiation was comparable to the impingement rate of the H2 or H2O molecule at the crystal surface from the residual gas. For the He irradiation at 820 K, blisters and exfoliation with large sizes were observed on the crystal surface, where impurities other than H and He were also enriched.

Retention of He implanted into W single crystals and the He irradiation effects on H behavior were studied by ion beam analysis techniques. During implantation of 4 He+ with 2–10 keV at 295 K, an accumulation of H started in the He implanted layer when the retained He concentration saturated. For the crystal irradiated by 10 keV He+ at 820 K, a remarkable increase of H was found in the He saturated layer, after stopping the implantation and cooling down the crystal below 400 K. Though blisters and exfoliation were observed for the surface irradiated at 820 K, less lattice disorder was found in the implanted layer and the thermal release of H occurred at lower temperature, in comparison with the crystal implanted at 295 K.