WEBINARS

Austenitic stainless steels are widely used as in-core materials in current nuclear systems, due to a combination of corrosion resistance, ductility, and other mechanical properties. However, in the next-generation nuclear systems that will be operated at higher temperatures and higher levels of neutron irradiation, the use of austenitic stainless steels is largely avoided mostly due to poor void swelling resistance. In this regard, our research group developed an austenitic SS with uniformly distributed nanosized NbC precipitates, named as ARES-6P, by controlling chemical composition and thermo-mechanical processing.

To demonstrate the radiation resistance, heavy ion irradiation was performed at high temperatures to the damage level of ~200 displacement per atom (dpa). The measured void swelling of ARES-6P was 2‒3%, which was considerably less compared to commercial 316 stainless steel and comparable to ferritic martensitic steels. In addition, the increment of hardness measured by nano-indentation was much smaller for ARES-6P compared to 316 stainless steel. Though some nanosized NbC precipitates were dissociated under relatively high dose rate (~5.0 × 10-4 dpa s-1), a sufficient number of NbC precipitates remained to act as sink sites for the point defects, resulting in superior radiation resistance. Both significantly less void swelling and less irradiation hardening indicate the superior irradiation resistance of ARES-6P for the application of next generation nuclear systems.

Dr. Ji Ho Shin recently completed his PhD at the Korea Advanced Institute of Science and Technology (KAIST) in the field of nuclear materials on the subject of “Development of nano carbide dispersed advanced radiation resistant austenitic stainless steels (NC-ARES) for reactor internals.” He worked on the development of next-generation nuclear materials, including Small Modular Reactor (SMR), Sodium Fast Reactor (SFR), and fusion reactor to demonstrate the superior radiation-resistant features. He is currently a post-doctoral fellow in the Department of Nuclear and Quantum Engineering (NQE). Dr. Ji Ho Shin is also the winner of the audience favorite presentation during the 2021 Pitch your Gen IV research competition.