CAREER: Molecular-Scale Behavior of Actinide Elements at the Mineral-Water Interface

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Professor Amy E. Hixon of the University of Notre Dame is supported by a CAREER award from the Environmental Chemical Sciences program in the Chemistry Division to study actinides. The actinide elements are those with atomic numbers 89-103 (i.e., actinium through lawrencium, including uranium, thorium and plutonium). All actinides are radioactive; that is, they release energy upon radioactive decay. Several actinides (e.g. uranium) are used in nuclear reactors and nuclear weapons. Americium is used in most modern smoke detectors. The actinides are important to society due to their use in medicine, power generation, and national security. Since the actinide elements are radioactive, they are far less studied than other elements on the periodic table. In this project, Dr. Hixon studies the environmental behavior of the actinide element plutonium using both experiments and models. The goal is to address the relationship between plutonium concentration, the particle size of the solid, and the structure of the solid. The education of a future workforce that understands the health and safety aspects of radioactive elements contributes directly to advancing national health and securing the national defense. By using the facilities at Los Alamos National Laboratory, this CAREER program gives students the opportunity to work within federal laboratory facilities leveraging and advancing new and novel techniques such as Pu-239 NMR spectroscopy. The nuclear energy lesson plan kits are a valuable resource for the South Bend Community School Corporation, which has a large minority student population. Finally, the "Get to Know Nuclear" Girl Scout events serve as a platform to inspire young women to study science, technology, engineering, and mathematics. This project addresses the sorption and reduction of plutonium at the solid-water interface. Experiments involve batch experiments and spectroscopic analyses, such as X-ray absorption spectroscopy, nuclear magnetic resonance spectroscopy, and magnetic susceptibility measurements. These approaches show how three variables affect the structure of plutonium associated with the solid. The first variable is plutonium concentration. The second variable is the concentration of aluminum in an iron mineral. The third variable is the particle size of the solid. Modeling shows how and why these variables are important and are used to predict the behavior of plutonium in new systems. Dr. Hixon is also developing lesson plans to teach high school students about radioactive materials and hosting events for local Girl Scouts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.