Investigation of gamma radiation effects on spectroscopic, thermal, and corrosion properties of the International Simple Glass (ISG)

•International Simple Glass (ISG) nuclear waste simulant subjected to γ-ray irradiation.•Basic structural, spectroscopic, and thermal properties evaluated.•Chemical durability assessed following the static-leach product consistency test (PCT).•EPR, optical absorption, and photoluminescence spectroscopy study performed.•Effect of heat treatment on γ-irradiated ISG evaluated.