2020年IAEA比对样品中总α和总β放射性分析

Determination of grossαand grossβradioactivity in IAEA-2020-intercomparison samples

目的对2020年国际原子能机构(IAEA)比对样品中总α和总β放射性测量实践进行总结, 以期对同类测量提供参考。方法按照比对要求, 薄层法分别以241Am、总Th、90Sr/90Y、40K和137Cs溶液为标准源, 测定水样、气溶胶样品中总α和总β放射性。厚源法和蒸发法分别以241Am、40K粉末为标准源, 测定水样、鱼样品中总α和总β放射性。结果薄层法测量结果的相对偏差和Z比分分别为4.12%~31.6%、0.14~1.71;厚源法联合蒸发法测量结果的相对偏差和Z比分分别为2.63%~32.5%、0.11~0.93, 可接受率为100%。结论一般情况下, 在样品测量时, 应选择与待测样品中可能存在的放射性核素类型、能量相近的标准源。对于事故应急监测, 宜采用薄层法;而一般的环境监测或实验室分析未知样品时, 宜先采用厚源法和蒸发法, 后续根据样品的放射性活度, 可结合薄层法进行相互比对。本工作为同类测量提供了技术参考。

Objective To summarize the practices in measuring the grossαand grossβradioactivity in IAEA-2020-intercomparison samples,which could be expected to be beneficial to the similar analysis and research.Methods With 241Am,Th,90Sr/90Y,40K and 137Cs solution as standard materials,the grossαand grossβradioactivity in water and aerosol samples were determined using thin source method.With 241Am,40K powder as standard materials,the grossαand grossβradioactivity in water and fish samples were measured using thick source method combined with evaporation.Results The result showed that the relative deviation and Z-score by using thin source method were 4.12%-31.6%and 0.14-1.71,respectively,and those from thick source combined with evaporation were 2.63%-32.5%and 0.11-0.93,respectively,with the acceptance rate being 100%.Conclusions Generally,standard material shall be selected in the same types of radionuclides and energies as in samples.The thin source method is appropriate for emergency monitoring in the event of an accident.The thick source combined with evaporation should be perfered to the environmental monitoring or the analysis of unknown samples in laboratory.And then an intercomparison should be done with thin source method based on the radioactivity in samples.This work can provide a technical reference for similar measurements.