Austenitic stainless steels are widely used in current commercial BWR and PWR systems as in-core and surrounding structural materials. These versatile steels have also been the main materials considered and applied for many advanced reactor technologies, including fast-breeder reactors and magnetic fusion reactors. For advanced reactors for higher temperatures or high lifetime damage levels, modified versions of the standard commercial stainless steel grades have been developed to provide improved performance properties and radiation resistance in specific reactor environments