Validated analytical measurement protocols for the fast and accurate determination of the uranium (U) isotopic composition (234U, 235U, 236U, 238U) of solid nuclear materials were developed employing ns-laser ablation (LA) coupled to multi-collector ICP-MS. The accuracy of the analytical procedure was assured by frequent (n = 65) analysis of a pressed pellet of certified isotopic reference material CRM U-030 (∼3 wt% 235U). The expanded uncertainty (k = 2) for the n(235U)/n(238U) ratio was as low as 0.05%, rising to 0.62% and 1.09% for n(234U)/n(238U) and n(236U)/n(238U) ratios, respectively. LA-MC-ICP-MS measurements of a pressed pellet of certified isotopic reference material CRM U-020 (∼2 wt% 235U) before analysis of each sample allowed calculation of the ion counter gains and mass bias correction. Both individual spot analysis and line scan analysis were used to measure n(234U)/n(238U), n(235U)/n(238U), and n(236U)/n(238U) ratios in two low-enriched UO2 pellets from the fourth Collaborative Materials Exercise (CMX-4), four seized low-enriched UO2 pellets intercepted from illicit trafficking and one metal sample consisting of depleted U. LA-MC-ICP-MS results of all investigated samples matched well with U isotope ratios obtained by thermal ionisation mass spectrometry (TIMS). This independent confirmation of the LA-MC-ICP-MS results by TIMS underpinned the high quality of generated analytical data. Acquisition of several thousand data points within a couple of minutes during line scan analysis yielded detailed information on the spatial distribution of the U isotopic composition of selected UO2 pellets, revealing straightforwardly their (in˗)homogeneity on the μm-scale. Calculating skewness and half width of the frequency distributions of the n(235U)/n(238U) amount ratio allowed the quantitative assessment of the (in-)homogeneity of the investigated samples. This information allows drawing conclusions on the starting materials used for the production of the pellets. From a nuclear forensics perspective, LA-MC-ICP-MS provides quick, accurate results on the spatial distribution of major and minor U isotopes while preserving the sample i.e. piece of evidence, essentially intact.

中文翻译：

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tsing 激光烧蚀测定固体铀材料中铀同位素比率的分析注意事项 多接收器 ICP-MS

使用 ns 激光烧蚀 (LA) 与多接收器 ICP-MS 耦合开发了经过验证的分析测量协议，用于快速准确地测定固体核材料的铀 (U) 同位素组成（234U、235U、236U、238U）。通过对经认证的同位素参考材料 CRM U-030（~3 wt% 235U）的压片进行频繁 (n = 65) 分析，确保了分析程序的准确性。n(235U)/n(238U) 比率的扩展不确定性 (k = 2) 低至 0.05%，n(234U)/n(238U) 和 n(236U)/ 的扩展不确定性上升至 0.62% 和 1.09% n(238U) 比率，分别。LA-MC-ICP-MS 在分析每个样品之​​前对经认证的同位素参考材料 CRM U-020（约 2 wt% 235U）的压丸进行测量，以计算离子计数器增益和质量偏差校正。单独的点分析和线扫描分析均用于测量两个低浓缩 UO2 颗粒中的 n(234U)/n(238U)、n(235U)/n(238U) 和 n(236U)/n(238U) 比率从第四次合作材料练习 (CMX-4) 中截获了四颗从非法贩运中截获的低浓缩 UO2 颗粒和一个由贫铀组成的金属样品。所有调查样品的 LA-MC-ICP-MS 结果与 U 同位素比率匹配良好通过热电离质谱（TIMS）获得。TIMS 对 LA-MC-ICP-MS 结果的这种独立确认为生成的分析数据的高质量奠定了基础。在线扫描分析过程中在几分钟内采集了数千个数据点，获得了有关所选 UO2 颗粒的 U 同位素组成的空间分布的详细信息，直接揭示它们在微米尺度上的（in˗）同质性。计算 n(235U)/n(238U) 量比的频率分布的偏度和半宽度允许对所研究样品的 (in-) 均匀性进行定量评估。该信息允许对用于生产颗粒的起始材料得出结论。从核取证的角度来看，LA-MC-ICP-MS 可提供有关主要和次要 U 同位素空间分布的快速、准确的结果，同时保留样品，即证据，基本上完好无损。该信息允许对用于生产颗粒的起始材料得出结论。从核取证的角度来看，LA-MC-ICP-MS 可提供有关主要和次要 U 同位素空间分布的快速、准确的结果，同时保留样品，即证据，基本上完好无损。该信息允许对用于生产颗粒的起始材料得出结论。从核取证的角度来看，LA-MC-ICP-MS 可提供有关主要和次要 U 同位素空间分布的快速、准确的结果，同时保留样品，即证据，基本上完好无损。