Nuclear reaction analysis of deuterium diffusion in Zr-2.5 wt% Nb pressure tube material

Nuclear reaction analysis (NRA) has been used to measure the diffusion coefficient of deuterium in Zr-2.5 wt% Nb pressure tube material. The measured diffusion coefficient is 1.13x10-10 m2 s-1 at 3000C and 1.23x10-10 m2 s-1 at 3500C. The results are in reasonable agreement with measurements carried out by vacuum extraction analysis. The value obtained for the diffusion coefficient at 3500C is lower than a prediction based on measurements at lower temperatures and may be showing the influence of the break-up of the β-phase, although some effect due to tube-to-tube variability cannot be discounted. NRA detects a surface deuterium peak which is shown to correlate with the bulk deuteride concentration. (orig.)