Investigation of the Effect of Radiation-Induced Shape Change of Fuel Assemblies on the Temperature Regime and Stress-Strain State of Fuel-Element Cladding

Abstract

Methods of calculating the temperature regime and stress-strain state of fuel elements in a sodium-cooled BN-600 are presented. Deformation effects and the local azimuthal temperature distribution of fuel elements with wire winding spacing in fuel assemblies are taken into account. The influence of radiation effects on the temperature regime and stress-state of the fuel elements is shown. The maximum stresses are observed in the section with maximum shape change. At run completion, as a result of nonuniform swelling of the cladding material, on the inner fiber of the cladding the compression stresses transform into tensile stresses and repeat the character of the temperature distribution along the cladding perimeter. The maximum inelastic accumulated strains (ε_c = 1.5%) occur at the point of greatest swelling and high tangential stress.