Anisotropy of in-reactor deformation of Zr-2.5Nb pressure tubes

Theoretical modeling and results from irradiation experiments show that the diametral strain rate of an internally pressurized (closed end) cold-worked Zr-2.5Nb tube increases as the resolved fraction of basal plane normals, f, increases in the radial direction and reduces in the transverse direction. At the same time the elongation rate decreases. The increased diametral strain rate results from an increased diametral creep rate, and a decreased (in magnitude) negative diametral irradiation growth rate. The decreased elongation rate results from a reduction in the axial creep component under the biaxial stress conditions