TY - GEN
T1 - Investigating Irradiation Creep of Zircaloy-4 Using In-Situ Proton Irradiation and Transmission Electron Microscopy
AU - Gillen, Conor
AU - Greaves, Graeme
AU - Thomas, Rhys
AU - Shaikh, Adeel
AU - Harrison, Robert
AU - Norris, Alistair
AU - Garner, Alistair
AU - Cole-Baker, Aidan
PY - 2022
Y1 - 2022
N2 - Under normal operating conditions, zirconium alloys in Pressurised Water Reactors (PWRs) can plastically deform in the presence of irradiation at stresses lower than the yield stress, resulting in component distortion and having a cascading affect upon other degradation mechanisms. In this feasibility study, dog-bone recrystallised annealed (RXA) Zircaloy-4 specimens were strained while under transmission electron microscopy (TEM) observation, producing point defects and dislocations. Repeated stop-go irradiation of 700 KeV Kr2+ ions at a flux of 1 x 1016 ions / m2s was found to impact dislocation movement, as is postulated in several mechanisms of irradiation creep. By comparing stills taken from video footage of dislocations during irradiation, the comparative speeds of individual dislocations, as well as general areas of crystallographic defects may be examined. By measuring the relative movement of features surrounding an electropolishing-induced hole at the centre of the gauge length, the effect of irradiation on the local strain can be analysed, with the results informing discussion around previously proposed creep mechanisms, such as I-Creep and the possibility of irradiation cascades causing repeated dislocation unpinning. Results suggest the impact of dislocation movement upon irradiation creep could be significant, although the contribution of mass transport mechanisms remain unclear.
AB - Under normal operating conditions, zirconium alloys in Pressurised Water Reactors (PWRs) can plastically deform in the presence of irradiation at stresses lower than the yield stress, resulting in component distortion and having a cascading affect upon other degradation mechanisms. In this feasibility study, dog-bone recrystallised annealed (RXA) Zircaloy-4 specimens were strained while under transmission electron microscopy (TEM) observation, producing point defects and dislocations. Repeated stop-go irradiation of 700 KeV Kr2+ ions at a flux of 1 x 1016 ions / m2s was found to impact dislocation movement, as is postulated in several mechanisms of irradiation creep. By comparing stills taken from video footage of dislocations during irradiation, the comparative speeds of individual dislocations, as well as general areas of crystallographic defects may be examined. By measuring the relative movement of features surrounding an electropolishing-induced hole at the centre of the gauge length, the effect of irradiation on the local strain can be analysed, with the results informing discussion around previously proposed creep mechanisms, such as I-Creep and the possibility of irradiation cascades causing repeated dislocation unpinning. Results suggest the impact of dislocation movement upon irradiation creep could be significant, although the contribution of mass transport mechanisms remain unclear.
M3 - Conference contribution
BT - 20th International Conference on Environmental Degradation of Materials in Nuclear Power Systems
ER -