Large Geometry Secondary Ion Mass Spectrometry (LG-SIMS) is one of the techniques used by the Network of Analytical Laboratories (NWAL) for determining the isotopic composition of uranium in particles collected on environmental samples as part of the International Atomic Energy Agency’s (IAEA) verification activities to assure the absence of undeclared nuclear materials and activities. While safeguards findings relating to environmental samples may only be made taking into account the high-quality results of the microprobe analysis (MPA), the data available from the Automated Particle Measurement (APM) screening can be very beneficial to IAEA evaluators within the Department of Safeguards. APM screening was developed for use by LG-SIMS operators to identify uranium-bearing particles on a planchet and to obtain an estimate of their 235U abundance; these data are then used for the selection of particles for the more accurate and precise microprobe analysis. Additionally, these data can be used by IAEA environmental sampling (ES) evaluators to complement the microbeam measurements by assessing the distribution of particles on a sample. This can provide valuable information related to the sampled location, potential cross contamination scenarios, etc. Furthermore, when combined with expedited sample logistics to minimize the time between sample collection in the field and sample receipt at the IAEA, APM data can be used to provide a very fast, initial indication of whether the declared enrichment limit has been exceeded, which is then subject to confirmation by microbeam measurements. This paper will describe in more detail (with the use of hypothetical examples) how APM data is used by IAEA ES evaluators and discuss potential future uses of APM data.
Year
2024
Abstract