The anisotropy of the high temperature deformation of Zircaloy-cladding tubes for nuclear fuel rods

The anisotropy of the high temperature deformation of Zircaloy-4 cladding tubes for nuclear fuel rods for pressurized water reactors has been investigated. The axial and tangential components of the deformation of internally pressurized tube samples during closed end creep rupture tests in air at 800°C have been measured. An axial contraction of the tube sample is observed. Using Hill's theory of plasticity the axial strain can be described by anisotropy coefficients which depend on the texture of the tube material. The anisotropy coefficients are quantitatively related to the orientation distribution of the basal poles in the radial/tangential plane of the tube sample. For the typical texture of Zircaloy cladding tubes of nuclear fuel rods for pressurized water reactors, an axial contraction has to be expected under the biaxial stress conditions applied.