Gamma-ray irradiation behavior of a hexagonal Ti–6Ta alloy applied in spent nuclear fuel reprocessing

Hexagonal near-alpha titanium alloy-like Ti–6Ta (in wt%) is widely used as a structural material in spent nuclear fuel (SNF) reprocessing plant equipment. In this work, the detailed microstructure and texture of the Ti–6Ta alloy were analyzed by using EBSD technique, followed by the Gamma-ray (γ-ray) irradiation experiments with a 60 Co isotope facility to simulate the γ-ray radioactivity of the short-lived fission fragments of SNF. Results showed that γ-ray irradiation-induced crystalline defects in hexagonal titanium was firstly observed and characterized. TEM results revealed the dislocation loops within α-titanium grains, whereas the loop size and number density peaked at the irradiation dose of 100 kGy, and then were obvious declined as the γ-ray radiation dose increased. The lattice parameters for the irradiated Ti–6Ta samples were slightly changed for the different irradiation dose cases. Moreover, Monte Carlo (MC) simulations further explained that the energy of primary knock-on atom (PKA) could reach the threshold energy of titanium or tantalum atom to induce the consequent vacancies and interstitials transformation into Frank dislocation loops in Ti–6Ta alloy. Graphical abstract