加速器质谱法测量含铀微粒中铀同位素比的方法研究

Methodological Study for AMS Measurement of Uranium Isotope Ratio in Uranium Particle

摘要: 准确测定含铀微粒同位素比在核保障中有重要的应用价值。本文采用将含铀微粒溶解并加入高纯Fe粉烘干的方法制样，采用中国原子能科学研究院的HI-13串列加速器质谱测量靶样中的同位素比。通过对CRM铀系列同位素标准样品的分析表明，该方法可测定高于10^-5的²³⁶U/²³⁸U同位素比；对于²³⁵U/²³⁸U同位素比在10^-4～10^-1范围内的含铀微粒，²³⁵U/²³⁸U同位素比相对扩展不确定度均小于10%。

Abstract: The accurate determination of uranium isotope ratio in uranium particle is essential for nuclear safeguards. Uranium particles were first dissolved, and then the solution was dropped in high purity iron powder and was dried and prepared for the target of accelerator mass spectrometry (AMS) in this paper. The target sample was measured by HI-13 AMS system at China Institute of Atomic Energy (CIAE). The certified reference materials (CRM) for uranium particles isotope ratios were analyzed. The results demonstrate that the method can be used for measuring the ²³⁶U/²³⁸U isotope ratio above 10^-5, and ²³⁵U/²³⁸U isotope ratio of 10^-4-10^-1 can be measured with better than 10% relative expanded uncertainty.