Anisotropic biaxial creep of zircaloy tubing

The creep characteristics of Zircaloy were studied by superimposed axial loads on internally pressurized thin-walled tubings. The temperature and stress dependences of the steady-state creep as well as the time dependence of the strain were evaluated from hoop creep of internally pressurized tubing. The biaxial creep behavior was characterized by monitoring the strains along the hoop and axial directions. Creep anisotropy parameters were determined both from the ratios of biaxial strain-rates at varied stress ratios and the creep locus at a constant energy of dissipation. These models were applied to predict the in-reactor performance of Zircaloy cladding. (author)