Application of Lead and Strontium Isotope Ratio Measurements for the Origin Assessment of Uranium Ore Concentrates

Abstract

Lead and strontium isotope ratios were used for the origin assessment of uranium ore concentrates (yellow cakes) for nuclear forensic purposes. A simple and low-background sample preparation method was developed for the simultaneous separation of the analytes followed by the measurement of the isotope ratios by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). The lead isotopic composition of the ore concentrates suggests applicability for the verification of the source of the nuclear material and by the use of the radiogenic (207)Pb/(206)Pb ratio the age of the raw ore material can be calculated. However, during data interpretation, the relatively high variation of the lead isotopic composition within the mine site and the generally high contribution of natural lead as technological contamination have to be carefully taken into account. The (87)Sr/(86)Sr isotope ratio is less prone to the variation within one mine site and less affected by the production process, thus it was found to be a more purposeful indicator for the origin assessment and source verification than the lead. The lead and strontium isotope ratios measured and the methodology developed provide information on the initial raw uranium ore used, and thus they can be used for source attribution of the uranium ore concentrates.

Nuclear Forensic Science: Analysis of Nuclear Material Out of Regulatory Control

“…Švedkauskaitė-LeGore (2007) found that radiogenic Pb isotope abundance ratios vary significantly between different U mines. Subsequent work revealed that Pb isotope ratios could be used in conjunction with trace elemental impurities to distinguish between UOC samples of differing origins (Švedkauskaitė-LeGore 2008), although Varga et al (2009) urged caution in the use of Pb isotope ratios as a signature for UOCs because of substantial withinmine variability. These authors also observed dilution of the intrinsic radiogenic lead signature of the ore by common lead during processing, in some samples to the extent that no radiogenic lead signature remained after processing.…”

“…These authors also observed dilution of the intrinsic radiogenic lead signature of the ore by common lead during processing, in some samples to the extent that no radiogenic lead signature remained after processing. Varga et al (2009) applied a common lead subtraction to constrain the radiogenic Pb isotopic composition of the ore. Using this radiogenic Pb isotopic composition, it is possible to calculate an age of the U ore deposit, although this approach is viable only if the radiogenic Pb signal is strong relative to the common lead signature.…”

“…The measured 87 Sr/ 86 Sr of UOCs varies over a wide range [0.7034 to 0.7606 and higher (e.g., Varga et al 2009)]. As a result, the 87 Sr/ 86 Sr ratio is useful for distinguishing samples of different origins as well as comparing with known samples.…”

“…As a result, the 87 Sr/ 86 Sr ratio is useful for distinguishing samples of different origins as well as comparing with known samples. Unlike Pb isotopes, which can exhibit significant within-mine variability, Sr isotopes are typically constant in samples from a single mine or mill (i.e., Varga et al 2009). Although a few UOCs have distinctively high 87 Sr/ 86 Sr ratios, in general there is considerable overlap between mines/mills, and the technique, like the others discussed in this review, must be used in conjunction with other signatures in order to uniquely identify UOCs from different sources.…”

Near infrared reflectance spectroscopy as a process signature in uranium oxides

“…To-date, much effort has focused on techniques, such as trace element and isotopic analysis, which have demonstrated the ability to link material to a likely geological source [2] [3]. Considerably less effort has been put forth in developing techniques to determine the chemical process history of nuclear materialsalso a desirable outcome of technical nuclear forensics.…”