Prediction of creep anisotropy in Zircaloy cladding
- Siemens Power Corp., Richland, WA (United States). Nuclear Division
Due to the hexagonal crystal structure of zirconium and the radial orientation of the basal poles in zircaloy cladding, the deformation of light water reactor Zircaloy fuel cladding is anisotropic. Plastic deformation of this cladding can be defined by the R and P factors that are the circumferential/radial; and axial/radial contractile strain ratios under uniaxial deformation along the axial and circumferential direction, respectively. The in-reactor deformation performance of the cladding can be modeled with good accuracy if the R and P values of the irradiation-induced creep are known. In a boiling water reactor (BWR) fuel assembly, most fuel rods have a hoop stress to axial stress ratio of about 2:1. The assembly also contains several fuel rods (tie rods) that connect the upper and lower tie plates. The tie rods have an additional stress component in the axial direction. BWR assemblies can, furthermore, contain water rods that are free of stress, and therefore, provide a measure of stress-free irradiation growth. Post-irradiation deformation measurement of these three types of rods are used to derive the R and P factors for BWR cladding during irradiation. Laboratory tensile and creep tests at several temperatures have been performed on five types of cladding to determine if a short-term text could be used to obtain R values representative of the in-reactor values.
- OSTI ID:
- 55667
- Report Number(s):
- CONF-930611--; ISBN 0-8031-2011-7
- Country of Publication:
- United States
- Language:
- English
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