Knowledge of the temperature dependence of hydrogen solubility is used to define the conditions necessary for brittle hydrides to be present in reactor components during service. The terminal solid solubility (TSS) of hydrogen is affected by several factors, including irradiation, cold work, and decomposition of the p phase in Zr-2.5Nb. TSS temperatures for specimens irradiated in Osiris, Halden, and CANDU® reactors are reported. TSS was measured on Zr-2.5Nb specimens using differential scanning calorimetry (DSC) to complete four heat-up/cool-down cycles (heat to a peak temperature and cool to room temperature at a rate of 10°C/min) followed by a 1-h anneal at 500°C, and then four more heat-up/cool-down cycles. As with Zircaloy, irradiation slightly decreases the TSS temperatures, but subsequent annealing increases them. These changes are attributed to an initial effect of irradiation damage and reconstitution of the p phase and reversal of these effects by annealing, as indicated by X-ray diffraction data showing reduced dislocation density and higher p-phase volume fraction after the specimens were annealed.

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18th International Symposium on Zirconium in the Nuclear Industry
Department of Mechanical and Aerospace Engineering

Nordin, H.M. (Heidi M.), Hilton, V. (Vicky), Buyers, A.W. (Andrew W.), Coleman, C.E. (Christopher E.), & McRae, G. (2018). Effect of irradiation on terminal solid solubility of hydrogen in Zr-2.5Nb. In ASTM Special Technical Publication (pp. 1136–1166). doi:10.1520/STP159720160044