Nuclear Fuel Materials under Extremes: Redox Behavior and Resulting Defect Structure

Oxide nuclear fuel materials and analogues are often subject to complex structural and chemical changes when exposed to extreme environments. For example, oxidation and buildup of fission products cause changes to the local- and long-range structure as well as the chemistry and stoichiometry of UO2 during operation in light water reactors. Highly ionizing energetic fission fragments have been shown to cause redox effects and associated defect structures in oxide nuclear fuel-type materials. The underlying mechanisms that lead to defect structures produced in a wider range of nuclear fuel material compositions and microstructures is not well understood. This research project focuses on redox effects and the resulting defect structure that are induced in nuclear fuel materials and analogues by extreme environments. A specific approach is utilized combining state-of-the art user facilities to both expose materials to extremes and characterize the effects on structure and chemistry with complementary analytical tools with comprehensive data analysis techniques. Knowledge gained from this work further enhance our understanding of the basic processes and mechanisms that dictate the behavior and performance of nuclear fuel materials under extremes