非平衡体系样品中^232 Th非破坏放射性测量方法研究

Study on the measurement method of non-destructive^232Th assay in non-equilibrium system samples

天然样品中^232Th的含量或活度浓度通常可采用γ能谱法测量其子体212Pb来实现,然而当样品中^232Th系列处于放射性非平衡状态时,γ能谱法很难给出准确的测量结果。在分析钍系列总α放射性比活度和各个γ核素放射性比活度的关系的基础上,结合平衡判断模型,探索总α-γ能谱方法理论基础;通过酸洗法模拟破坏其平衡状态的实验方法,用标准物质验证总α-γ能谱法的可行性,纯钍放射性平衡判断模型中总α-γ能谱法与对照方法相比,相对偏差<20%。

The content or activity concentration of^232Th in natural samples can be realized by measuring its daughter 212Pb byγ-ray spectrometry.However,when the^232Th series in the sample is not equilibrium,it is difficult to give the accurate measurement results byγ-ray spectrometry.In this paper,the theoretical basis of the grossα-γenergy spectrum method is explored by analyzing the relationship between the grossαspecific activity of natural thorium samples and the specific activity of eachγnuclide.The experimental method of removing thorium by acid pickling was used to simulate destroying its equilibrium state.The feasibility of grossα-γenergy spectrum method was verified by standard material.A theory basis and more accurate method for non-destructive^232Th radio analysis was provided.The measurement error is less than 20%for^232 Th by grossα-γenergy spectrum comparing to the ICP-MS.