Sri Tapaswi Nori¹, Alejandro Figueroa¹, Jonova Thomas¹, Gyuchul Park¹, Walter Williams¹, Hemant Sharma², Jun-Sang Park², Peter Kenesei², Jonathan Almer², Zhengrong Lee³, Mark Warren³, Jeff Terry³, Maria Okuniewski¹; ¹Purdue University, ²Argonne National Laboratory, ³Illinois Institute of Technology

High-temperature ultra-fine precipitation strengthened (HT-UPS) steel is a high-strength, creep resistant advanced austenitic stainless steel at elevated temperatures (>400℃). It is a candidate structural material for advanced nuclear reactors. However, its neutron irradiation tolerance is not well understood. In this context, this research utilizes non-destructive synchrotron X-ray techniques such as high-energy diffraction microscopy (HEDM), micro-computed tomography (μ-CT), and X-ray absorption spectroscopy (XAS) to characterize the neutron-irradiation induced defect structures at multiple length scales. HEDM and μ-CT provide three-dimensional micromechanical state information for the grains and microstructural density changes due to the varying compositions within a material, respectively. XAS provides the local chemical environment information around an absorbing atom. These experiments were conducted on samples that were unirradiated and neutron-irradiated up to ~0.3 dpa at ~600℃. A comparative study between these irradiation conditions will be presented to explain the microstructural and micromechanical effects of irradiation.