Nuclear Science User Facilities 90 The designs of the next genera- tion of nuclear reactors call for the development of materials that can withstand severe neutron irradiation over a wide range of temperatures. Fe-Cr-based alloys are leading candidates for cladding and core structure applications in reactors. Radiation induced solute redistribution results in the degrada- tion of mechanical properties and structure integrity.This research focused on the microstructure and microchemistry characterization of high dose irradiated Fe-Cr alloy by advanced electron microscopy and atom probe tomography. Project Description Fe-9Cr alloys are leading candidates for cladding and core components in the next generation of nuclear reactors. Two issues that limit their lifetime at high doses are hardening at low temperatures and doses, and void swelling at high doses and intermediate temperatures.A fundamental understanding of the effects of carbon in these alloys will aid in overcoming these obstacles. Surveys of irradiation behavior of alloys by neutron and ion irradiation indicate that the nucleation and growth kinetics of radiation induced defects are strongly influenced by the minor elemental additions.The hypothesis is that carbon vacancies can trap small dislocation loops and prevent Effects of Carbon Addition on Solute Redistribution in Fe-9Cr Alloys Under Irradiation Cheng Sun – Oak Ridge National Laboratory /Idaho National Laboratory – Figure 1. EBSD mapping showing the δ-ferrite phase in an equiaxed morphology and tempered martensite phase in a lath structure. The portion of high- angle grain boundaries in this Fe-9Cr alloy is 77.5%.