Gamma spectrometry is widely used for radionuclide activity measurement of environmental sample including 226Ra in soil because it is versatile, easy to implement, non-destructive, and relatively cheap compared to other methods. By gamma spectrometry, 226Ra can be determined directly using its energy peak of 186.2 keV or indirectly by its decay products which are in secular equilibrium with 226Ra, i.e. 214Bi and 214Pb. However, both methods have challenges where for direct measurement, interfering from 235U energy peak of 185.7 keV can add significant contribution to the 186.2 keV of 226Ra gamma peak while for indirect measurement using energy peaks of 214Bi and 214Pb, decay products of 222Rn gas, longer time (at least 21 days) for their equilibrium ingrowth is needed and radon tightness of sample container must be ensured. In some measurements, the equilibrium could not be reached due to radon leakage from sample container. Therefore, in this paper, the radon leakage fraction from three different sealing methods of Marinelli beaker used in soil activity measurement were studied using HPGe detector and radon accumulation chamber with RAD7. The three sealing methods were only lid without sealing (MB1), sealed with paraffin film (MB2), sealed with silicone glue and vacuumed plastic bag (MB3) and their leakage fractions were 53%, 30%, and negligible leakage, respectively. Significant radon leakage from MB1 and MB2 have caused underestimation of 226Ra activity concentration measured by indirect gamma spectrometry. The study result recommends using MB3 sealing method for gamma spectrometry measurement because it is simple and cheap and has negligible leakage, moreover, its vacuumed plastic bag facilitates visual inspection to possible radon leakage.

中文翻译：

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样品容器中ra泄漏的测定，用于γ光谱测量226Ra。

伽马能谱法广泛用于环境样品（包括土壤中的226 Ra）的放射性核素活度测量，因为它比其他方法通用，易于实施，无损且相对便宜。通过伽马能谱法，可以直接使用其能量峰值186.2 keV来确定226Ra，或通过其与226Ra处于长期平衡状态的衰变产物（即214Bi和214Pb）间接确定。但是，这两种方法都存在挑战，在直接测量中，受到235U能量峰值185.7 keV的干扰可能会对226Raγ峰的186.2 keV产生重大影响，而对于使用214Bi和214Pb能量峰的间接测量，222Rn气体的衰减产物，更长的时间需要至少21天的时间以使其平衡向内生长，并且必须确保样品容器的ra气密性。在某些测量中 由于ra从样品容器中泄漏而无法达到平衡。因此，在本文中，使用HPGe检测器和带有RAD7的ra积累室，研究了三种Marinelli烧杯用于土壤活度测量的密封方法中的leakage泄漏分数。三种密封方法分别为无盖密封（MB1），石蜡膜密封（MB2），硅酮胶密封和真空塑料袋密封（MB3），其泄漏率分别为53％，30％和可忽略不计。MB1和MB2的大量ra泄漏导致低估了间接伽马光谱法测得的226Ra活性浓度。研究结果建议使用MB3密封法进行伽玛光谱测量，因为它简单，便宜且泄漏量可忽略不计，而且，