Uranyl peroxide materials and their role in radical formation

The research within this dissertation was supported by start-up funds from the College of Liberal Arts and Sciences and the Department of Chemistry at the University of Iowa, Nuclear Regulatory Commission Faculty Development Grant (NRC 31310018M0042), and the U.S. Department of Energy (DOE), Office of Science, Office of Workforce Development for Teachers and Scientists, Office of Science Graduate Student Research (SCGSR) program, which is administered by the Oak Ridge Institute for Science and Education (ORISE) and managed by ORAU (contract no. DE-SC0014664) for the DOE. Further support was provided by the Post Comprehensive Exam fellowship from the University of Iowa.

This dissertation looks to understand the role certain uranium materials play at the back end of the nuclear fuel cycle during recycling. During nuclear fuel reprocessing, the uranium materials must be dissolved in aqueous media which can then be chemically extracted from undesired nuclear reaction products that are a radiation hazard and prevent the further fission for the generation of electricity in nuclear reactors. The aqueous solution formed can contain radical and radical forming chemicals that can form and then interact with uranium in solution or the extractants being used. Some of these radicals react with uranium materials to form the uranium minerals studtite and metastudtite or in this dissertation shows how they can form 3-dimensional clusters termed uranyl peroxide clusters, and shows how certain radical form. Then species like OH are more likely to oxidize extractants used in uranium separation, thereby affecting the efficiency of a uranium extraction. All materials are characterized structurally using single crystal X-ray diffraction and spectroscopically using infrared and Raman spectroscopy, in addition to the radicals produced during and post synthesis through electron paramagnetic resonance (EPR).