地域溯源指示剂143Nd/144Nd同位素比值的高精度测量研究

核恐怖活动是当今国际社会安全稳定面临的重要威胁。铀矿石是核工业中提炼浓缩铀和制备核纯级铀的基本原料，因此其地理溯源研究也成为核取证分析的重要目标。由于稀土元素Nd的同位素组成差异可指示铀矿成矿过程中的地质变化，因此可用作铀矿石地理溯源的理想地域指示剂。本项目拟开发基于热电离质谱的143Nd/144Nd同位素比值高精度测量方法，通过化学分离与电离温度调节等相结合的方式解决主要干扰元素Sm、Ce分离的问题，去除同量异位素质量峰的干扰；同时解决Nd离子流信号增强、氧同位素效应校正与同位素比值质量校正等关键测量难题，最终实现铀矿石中ng量级Nd的143Nd/144Nd同位素比值精确测量。本项目的实施能为铀矿石、黄饼等核材料的地理溯源提供有力的技术支持；同时还可为143Nd/144Nd同位素比值在环境示踪、地球化学及核取证溯源等领域的实际应用提供科学基础。

Illicit trafficking of radioactive, especially nuclear materials poses a serious threat to the international community, In order to prevent the illicit trafficking and to reinforce the protection measures, the geographical origin and history of the illicit uranium ores have to be identified, as that they are the indispensable raw material of enriching uranium and manufacturing nuclear weapons. The variations of 143Nd/144Nd contribute to reflect the source and the age of uranium ores, thus it is used as an useful tool for the identification and origin assessment of uranium ore for nuclear forensic purposes. This proposal planned to establish an analytical method for the high-precision determination of the isotopic ratio of 143Nd/144Nd at trace level (ng) based on thermal ionization mass spectrometry (TIMS). The isobaric interferences of Sm and Ce would be avoided through chemical separation and the optimization of TIMS measuring parameters. Meanwhile, the problems related to the ionization of Nd atoms and the oxygen isotopic correction, as well as the mass bias correction would also be solved. The success of this work would introduce a new tool for geographic origin identification of uranium ores or uranium ore concentrates (yellow cakes) in nuclear forensics studies. Additionally, it would provide a scientific basis for the practical application of the isotopic ratio of 143Nd/144Nd in the fields of environmental isotope tracing and geochemistry studies.