有源-无源γ能谱分析方法在分析环境样品中放射性核素的应用

Application of sources and sources-less methods ofγspectrometry for analysis of radionuclides in environmental sample

目的验证无源效率刻度技术在测量环境样品中放射性核素含量应用中的可行性。方法选取500 g食品灰和土壤,作为实验样品,分别使用灰样标准源和土壤标准源对实验样品中40K、226Ra、232Th、238U和215Bi的比活度值进行定值,记为有源测量结果值;使用Φ75 mm×H35 mm和Φ75 mm×H70 mm两种样品盒,分别将实验样品制成不同密度的待测样品,使用无源效率刻度技术(LabSOCS)分析各密度样品中放射性核素比活度值,记为无源测量结果值,最后与有源测量结果值进行比较,并计算有源-无源测量结果值相对偏差。结果食品和土壤样无源效率刻度结果值与有源测量结果值的偏差在±15%内的分别占96.15%和91.30%。结论无源效率刻度技术在分析环境样品中放射性核素比活度的应用中具有可行性。

Objective To verify the feasibility of source-less efficiency calibration technique in measuring radionuclides in environmental samples.Methods 500 g food ash and 500 g dry soil were extracted as random experimental samples,then the specific activities of 40K,226Ra,232Th,238U and 215Bi were confirmed by ash standard source and soil standard source,and the values were defined as sources measurement results.Furthermore,the samples were made into samples with different densities to be tested,packed using two sample boxes ofΦ75 mm*H35 mm andΦ75 mm*H70 mm,and their specific activities of 40K,226Ra,232Th,238U and 215Bi were denoted as sources-less measurement results.Finally,the radionuclides specific activities calculated by source-less efficiency,were compared with active specific activity.Results The deviation between the measured value of food and soil samples and active specific activity is within±15%,accounted for 96.15%and91.30%,respectively.Conclusion Source-less efficiency calibration technique can be used to analyze the radionuclides specific activity in environmental samples.