Neutron and Ion Irradiation Studies on Advanced Steels Using the Nuclear Science User Facilities

For nuclear reactor structural materials, irradiation is capable of inducing a series of microstructural modifications, such as dislocation loops/network, selective elemental segregation and precipitation, voids and helium bubbles, leading to the degradation in structural materials' performance through irradiation hardening and embrittlement, swelling, irradiation creep, etc. Since radiation poses challenges for structural applications in nuclear reactors in multiple aspects and the underlying mechanisms are often interconnected, radiation effect studies need well-designed test matrix and proper characterization techniques. The Nuclear Science User Facilities (NSUF) offer extensive capabilities for studying radiation effects in nuclear fuels and structural materials. This research covers both neutron and ion irradiation studies carried out using a variety of instruments through the NSUF. The neutron irradiation ferritic ODS steel MA957 was accomplished utilizing the neutron irradiation capability of the Advanced Test Reactor (ATR) and the post-irradiation examination (PIE) capabilities of the Center for Advanced Energy Studies (CAES). The neutron-irradiated specimens were characterized using transmission electron microscopy (TEM) and atom probe tomography (APT). The in situ TEM ion irradiation study on austenitic stainless steel (SS) 316H was completed using the IVEM-Tandem facility at Argonne National Laboratory