Determination of REE in uranium bearing-material for nuclear forensics purposes using ICP-MS

Abstract

Nuclear forensics is a scientific discipline that focuses on nuclear or radioactive material and aims to provide information on the intended use, history, and even origin of the material. It examines and evaluates the signatures in nuclear and other radioactive materials to assist in criminal investigations involving these materials. The information obtained from forensic investigations needs to be accurate and precise for the evidence to be accepted in court. By using inductively coupled plasma mass spectrometry (ICP-MS), a new and straightforward analytical method has been created for the detection of lanthanides (rare-earth elements) in uranium ore and Uranium Ore Concentration. Rare earth elements (REE), called lanthanides, show consistent patterns under a variety of geochemical conditions. The aim of this project was to determine REE in uranium bearing material for nuclear forensics purposes using ICP-MS. The TRUTM resin was used for a selective extraction chromatographic separation of lanthanides, which was followed by ICP-MS analysis. To improve ionization efficiencies for determining REE concentrations, the chemical separation strategy was intended to limit matrix effects. Four (4) UOC and two (2) uranium ore samples from Witwatersrand basin in South Africa were subjected to the technique to measure REE abundances. Ce/Ce*, Eu/Eu*, LaN/YbN, LaN/GdN, and GdN/YbN were the few element ratios that seem to contain substantial information regarding sources. According to the findings, the total REEs (ΣREE) concentrations in several UOC samples were in the following order: UOC4 (15634,541 ppb) > UOC2 (983,972 ppb) > UOC1 (390,182 ppb) > UOC3 (182,968 ppb). For uranium ore samples, the ΣREE concentrations were: U ore1 (12486,420 ppb) > U ore2 (8413,640 ppb). While UOC1, UOC2, and UOC3 of the normalized REE/Cl chondrites pattern of UOC exhibited light rare earth elements (LREE) enrichment and heavy rare earth elements (HREE) depletion with positive Cerium anomalies and negative Europium anomalies, UOC4 demonstrated the opposite, with depletion LREE and HREE enrichment with a large negative Europium anomaly. The enrichment of the medium REEs was more pronounced than that of the LREEs and HREEs. U ore1 and U ore2 indicated positive Ce anomalies and negative Eu anomalies, as shown in the normalized REE/Cl chondrites pattern and their ratios of (LaN/GdN) and (GdN/YbN), ranged from 0.932 to 3.665 and 1.383 to 3.919 respectively. To evaluate their statistical significance in the observed variations, REEs for UOC and uranium ore samples were determined from the acquired data and subjected to ANOVA. The findings showed that among the analysed mining sites, REEs used to determine origin location, exhibited significant variation. It has been proven that these techniques can precisely measure the REE concentration of well-characterized UOC and uranium ore samples. The REE pattern was utilized for the identification and origin assessment of UOC and uranium ore samples. By doing so, it is simple to confirm the source of an unknown substance by comparing the pattern to that of a known sample. The provenance of the material can also be determined in numerous circumstances even when there is no reference sample available due to characteristic patterns, in contrast to other indicators utilized for nuclear forensic research. Finally, the findings provided in this dissertation can be a helpful tool for forensic nuclear investigations, supporting the fight against the illicit trafficking of nuclear materials.