Application of Texture in Predicting Nuclear Fuel Cladding Creep

X-ray diffraction techniques have been used to measure the texture of Zircaloy-4, which is described quantitatively by the crystallite orientation distribution function (CODF). Procedures for evaluating the anisotropy parameters in the modified Hill equation (R and P) from the CODF and their use in predicting creep behavior are reviewed. Alternatively, the same anisotropy parameters can be obtained from creep test data using appropriate mechanical deformation concepts. These R and P parameters are used to predict the creep behavior of fuel rod cladding both out of pile and in pile. The procedures involved in obtaining the anisotropy parameters from either crystallographic texture data or creep test data are summarized. These two approaches, previously discussed separately in the literature, are brought together for a direct comparison. Predictions of creep behavior based on texture measurements are compared with creep data. The utility of the anisotropy parameters in predicting postirradiation cladding dimensions is illustrated by reviewing the work of another research group. Excellent agreement between their model predictions and experimental results of postirradiation examination is observed.