Numerical evaluation of long-term neutron irradiation damage on reinforced concrete (RC) members

In the long-term operation of nuclear power plants (NPPs), irradiation can adversely affect the behavior of reinforced concrete (RC) members because of the degradation of the constituent materials. Degradation of concrete may be associated with the volume expansion of concrete due to irradiation, which is known as radiation-induced volume expansion (RIVE). As the compressive strength of concrete decreases under irradiation environments, the yield stress increases, and the ductility of steel decreases. Furthermore, the material properties of concrete and reinforcing steel vary within the cross-section of RC members because of the flux attenuation. In this study, such complicated changes in the material characteristics are systematically considered by using a simple fiber modeling approach to analyze the RC member behaviors. The effects of RIVE on the flexural members are computed by employing compatibility and equilibrium conditions. Based on the proposed framework, the behaviors of RC members are investigated under static and seismic loading conditions. The computational results demonstrate that the irradiation on RC members leads to changes in the structural characteristics such as the maximum load capacity, ductility, toughness, and the maximum spectral acceleration and corresponding period. Therefore, the irradiation effects must be carefully considered in RC structural analyses.