Development of radiation-tolerant austenitic stainless steels for advanced reactor applications

Significant, and in some instances revolutionary, advances in materials properties are necessary to meet the demanding conditions that will be experienced by reactor structural and cladding materials in the next generation of nuclear energy systems, where fuel burn-ups and operating temperatures are expected to be substantially greater than in current reactors. The radiation resistance of austenitic stainless steels (SS) widely used in current commercial nuclear reactors may be limiting in terms of dimensional stability and susceptibility to irradiation assisted stress corrosion cracking (IASCC). Recently, efforts to improve radiation-tolerance of austenitic SSs have had considerable success. The present paper will review the major in-reactor austenitic SS degradation mechanisms that will be important for advanced reactor systems, describe the genesis of radiation damage mitigation strategies and summarize the most noteworthy results from recent efforts to optimize alloy radiation tolerance through a combination of mitigation strategies. A combination of adding Zr as an oversized-solute additions and increasing the fraction of low energy grain boundaries through thermomechanical treatment dramatically improved the radiation tolerance of model austenitic SS alloys.