^(220)Rn子体测量的平衡因子法分析

Equilibrium factor method for measurement of ^(220)Rn progeny

为了实现对220 Rn子体长期、有效的测量,人们一直希望利用类似评价222 Rn子体浓度的平衡因子法来实现,即通过测量220 Rn气体浓度,再根据220 Rn气体与子体之间的平衡因子评价220 Rn子体浓度。以往这一方法受到220 Rn子体浓度分布不均且随时间变化明显的限制。最新的研究结果显示,220 Rn与其子体之间可能在长时间范围内存在一定的比例关系。该文以一系列在实验室和实地测量的结果为基础,总结了大量以往研究中的数据,系统地分析了220 Rn与子体的室内分布情况,给出了220 Rn平衡因子随与墙距离的变化曲线,通过对用以往测量结果计算得到的平衡因子值与本研究结果的比较验证了使用平衡因子法评价220 Rn子体在较长时间范围内浓度的适用性。

Long-term, effective measurements of 222Rn progeny are often based on measurements of the 222Rn concentration. Assuming equilibrium between the 222Rn and its progeny, the 222Rn progeny concentration can be found by measuring the ZZZRn gas concentration. However, this method is limited for the measurements of the Z20Rn progeny concentration because the 220Rn progeny concentrations are not uniform or vary with time. The proportions between 220Rn and its progeny are only valid after a long time range. This article summarizes a broad range of research data from laboratory and field measurements to analyze the indoor distribution of 220Rn and its progeny and give a relationship between the equilibrium factor and the distance from the wall, and validates the applicability of using equilibrium factors between 220Rn and its progeny to evaluate 220Rn progeny concentrations at long time ranges.