EXPLORATION OF PRE- AND POST-DETONATION NUCLEAR FORENSICS

Nuclear forensics seeks to determine the physical, chemical, elemental and isotopic characteristics of nuclear material with unknown origin and has two aspects—pre-detonation and post-detonation. Pre-detonation nuclear forensics focuses on interception and identification of nuclear materials, whereas post-detonation nuclear forensics focuses on characterizing and understanding the nuclear device used and provenance of material. The chondrite-normalized rare earth element pattern of a uranium-bearing material provides insight into the original ore type and location. Therefore, the first goal of this work was to investigate rare earth element interactions with UO₂ as a function of pH in an effort to intentionally change the rare earth element signature of the powder. The removal of rare earth elements from the aqueous phase of a batch system was monitored using inductively coupled plasma-optical emission spectrometry (ICP-OES), and X-ray fluorescence (XRF) was used to determine if rare earth elements precipitated from solution. The second goal of this work, related to post-detonation nuclear forensics, was to synthesize homogenous surrogates for debris material. The sol-gel approach was used to synthesize material as a function of metal alkoxide solution (tetramethoxysilane (TMOS), tetraethoxysilane (TEOS) and tetrabutoxysilane (TBOS)) and catalyst (hydrochloric acid and acetic acid). The optimal product minimized time to gelation, while maximizing extent of polymerization. XRF analysis of sintered products was performed to determine homogeneity.