Atoms, Alloys, and Aging: Engineering Safer Nuclear Systems

Nuclear power plants generate approximately 16% of the United States' electricity and play a critical role in delivering low-carbon energy. A key challenge in meeting growing energy demands is understanding the long-term behavior of structural materials as plant lifetimes are extended from 40 to 60 years and beyond. Nickel-chromium-based alloys are widely used for their corrosion resistance and mechanical stability at high temperatures. However, these alloys can undergo phase transformations during long-term thermal aging or irradiation, leading to the formation of brittle intermetallic phases. This transformation is associated with reduced ductility and increased brittleness, raising concerns about component reliability. Studying this transformation is challenging because it may take several decades to occur under normal operating conditions. In this work, we accelerate the transformation using irradiation and elevated temperature testing. We also employ atomistic simulations – computational methods that model the behavior of materials at the atomic level – to understand the mechanisms behind phase formation. Together, these approaches enable us to build predictive models of how mechanical properties evolve over time and provide guidance to the industry on component lifetimes.