An understanding of stress rupture behavior of zirconium alloy cladding tubes is of paramount importance for applications in nuclear reactors. Stress rupture properties of recrystallized Zircaloy-4 alloy were evaluated using burst testing of closed-end thin-walled tubing at varied test temperatures and internal pressures. The rupture data are correlated using the Larson-Miller parameter. The uniform circumferential elongations were also measured from which the hoop creep rates were calculated. These results were fitted to Monkman-Grant relationship with the aim of extrapolating the data to in-service stress levels. Furthermore, the creep data were plotted according to the Dorn equation where a transition in deformation mechanism from ‘power-law’ to ‘power law breakdown’ for Zircaloy-4 was noted. TEM studies corroborated the transition in mechanism from the power-law regime to a power-law breakdown regime.

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