Fracture behavior of cold-worked 316 stainless steels irradiated up to 73dpa in a pressurized water reactor was investigated by impact testing at −196, 30 and 150°C, and by conventional tensile and slow tensile testing at 30 and 320°C. In impact tests, brittle IG mode was dominant at −196°C at doses higher than 11dpa accompanying significant decrease in absorbed energy. The mixed IG mode, which was characterized by isolated grain facets in ductile dimples, appeared at 30 and 150°C whereas the fracture occurred macroscopically in a ductile manner. The sensitivity to IG or mixed IG mode was more pronounced for higher dose and lower test temperature. In uniaxial tensile tests, IG mode at a slow strain rate appeared only at 320°C whereas mixed IG mode appeared at both 30 and 320°C at a fast strain rate. A compilation of the results and literature data suggested that IG fracture exists in two different conditions, low-temperature high-strain-rate (LTHR) and high-temperature low-strain-rate (HTLR) conditions. These two conditions for IG fracture likely correspond to two different deformation modes, twining and channeling.