This special issue includes 12 pertinent manuscripts addressing the varied technical issues associated with the long-term operation of nuclear power plants (NPPs). Five manuscripts focus on the effects of gamma and neutron irradiation on concrete and its constituents, bridging the gap between the fundamental understanding of the effect of gamma irradiation and the advanced modeling techniques using lattice-based models that are applied at varied scales to provide predictive simulation of the physical and engineering properties of concrete-forming aggregates, concrete, and the concrete biological shield. Two papers complement this research by presenting - a novel petrographic x-ray‒based characterization method, and - a method to implement advanced characterization of the aggregate forming mineral phases into a FFT based simulation framework. Notably, this pathology is addressed in this issue in two papers focused on the modeling and monitoring of the structural performance of ASR-affected shear walls. The effects of chemical attacks caused either by sulfate ingress or carbonation are presented in this special issue, with a focus on the effects of the actual operating conditions in NPPs. A discussion of the structural performance of concrete structures that support vibrating equipment such as that found in a turbine building of an NPP is also included.