Texture inhomogeneity in Zircaloy-4 and Zr-1%Nb cladding tubes

Re-orientation of hydrides platelets along the radial direction during reactor operation adversely affect the mechanical properties and may lead to failure of the cladding tube. Until now many factors have been reported as being responsible for the hydride re-orientation along the radial direction. In the present study, texture inhomogeneity along radial direction is investigated and is considered as one of the main factors responsible for hydride reorientation. Texture of the top and bottom layers of Zircaloy-4 and E110 alloy was measured using X-ray diffraction and electron back-scattering diffraction (EBSD) techniques. Texture results obtained by X-ray diffraction technique was used to compare the texture inhomogeneity in Zircaloy-4 and E110 alloy. Kearn's f parameter was used to calculate differences in thermal expansion coefficients at different thickness layers in both alloys. The stress generated by differences in thermal expansion can contribute to hydride re-orientation and cracking of the fuel cladding. Zircaloy-4 texture is more inhomogeneous than E110 alloy texture. (author)