Enhanced Analytical Capabilities for Nuclear Forensic Applications

Nuclear forensic analysis is a key component of United States national nuclear security. A strong nuclear forensic analytical capability strengthens both national and global security by providing a deterrent to bad actors and rogue states who seek to engage in nuclear terrorism or warfare. In order to be effective, nuclear forensic scientists must be able to rapidly achieve highly-accurate and -precise physical, chemical, and isotopic measurements of illicit nuclear materials. The work presented in this dissertation aims to contribute to the efficacy of nuclear forensic science by developing reference materials that allow for rapid analytical techniques to be implemented in nuclear forensic investigations. Two reference materials are presented herein. First, a natural uraninite known as the Happy Jack uraninite has been fully characterized with respect to both its chemical (major, minor, and trace element) as well as its uranium isotope compositions. It is remarkably homogeneous with respect to its rare earth element abundances and will allow for rapid, in situ measurements of uranium-rich matrices at high spatial resolution. Second, an adaptable synthesis has been developed that allows for the production of homogeneous reference materials characteristic of post-detonation nuclear debris that will similarly allow for the rapid analysis at high spatial resolution of post-detonation materials. This synthesis can be tailored to be representative of a variety of urban and rural environments, making it a versatile method for nuclear forensic science.

This dissertation also examines the behavior of uranium-molybdenum systems. Molybdenum isotopic fractionation in uranium ores is investigated as a potential fingerprint that can be used to identify the origin or processing history of raw ores as well as manufactured uranium ore concentrates. Additionally, the first thermodynamic measurements of a synthetic uranyl molybdate, meta-iriginite [(UO2)Mo2O7(H2O)2] are presented. By understanding the conditions in which uranyl molybdates are likely to form and persist, nuclear forensic investigators may be able to determine the processing history of a sample based in part on the presence or absence of uranyl molybdate compounds.