316L stainless steel has been widely used for structural component applications in irradiation environments. The impact of manufacturing or service-induced defects on material tensile response and fracture behavior has been a longstanding concern. In this study, electron backscattering diffraction and finite element methods have been utilized to examine and model the tensile response of 316L stainless steel with different notch geometries. The tensile response is influenced by twinning at room temperature, while it is completely absent at temperatures higher than 200°C. In addition, irradiation exposure increases the yield point of the material and reduces the ductility. It is found that the larger plastic deformation area and severe tip blunting in ductile, unirradiated material promote uniformly distributed post-yield strain hardening processes. In this case, fracture initiates internally for tensile and C-notched specimen geometries, but from the notch tip for sharp V-notched specimen geometries. When irradiation-induced hardening is considered, similar fracture modes are found, however, strains to fracture are significantly reduced.