Diffusion of deuterium in Zr-2.5Nb alloy under neutron irradiation

▶ The effects of fast neutron irradiation on the diffusivity of deuterium in unirradiated Zr-2.5Nb pressure tube material have been determined. ▶ Samples of 3 mm wide × 3 mm thick and with lengths of 60 mm, 102 mm and 124 mm, which were machined from the longitudinal direction of a piece of unirradiated Zr-2.5Nb pressure tube and deuterided at one end were used in the measurements. ▶ The experiments were carried out using the U-2 Loop of NRU reactor at the Chalk River Laboratories. ▶ The results show that deuterium diffusion in Zr-2.5Nb pressure tube material during irradiation at a fast neutron flux of about 5 × 1017 nm−2 s−1 is not significantly different from that measured in the absence of neutron flux.