低水平环境放射性核素比对标准样品的研制

Preparation of Low-level Environmental Radionuclide Calibration Samples for Proficiency Tests

选取位于黄土高原地区峁顶部位采集黄土样品作为土壤标准样品的基质来源,通过无掺合放射性核素的方法制作了低水平环境放射性核素比对标准样品,并采用两套γ谱仪测量系统对标准样品进行均匀性检验和定值。分析结果表明,标准样品中,137Cs的比活度为4.2 Bq/kg,不确定度0.3 Bq/kg(1s);210Pb的比活度为80.4 Bq/kg,不确定度为8.4 Bq/kg(1s)。标准样品中不含其他人工放射性核素,137Cs和210Pb含量适当且均匀。3组样品的均匀性检验结果表明,137Cs和210Pb比活度分析结果的标准偏差分别为0.22Bq/kg和2.10 Bq/kg。3组样品中137Cs和210Pb的比活度分别在0.05水平上无显著差异,均匀性较好。该标准样品发放到亚太地区IAEA合作项目的6个成员国进行137Cs和210Pb比活度的分析比对,比对结果表明该物质均匀性良好。

Loess samples collected at mountain ridge sites on loess plateau terrain were selected as matrices for soil reference materials.Low-level environmental radionuclide calibration samples were made through a non-blending environmental radionuclides method.Homogeneity and reference samples values were determined using two distinct gamma spectrometry systems.The measurement results indicated that the activity of 137Cs was 4.2 Bq/kg with an uncertainty of 0.3 Bq/kg（1s）,the activity of 210Pb was 80.4 Bq/kg with an uncertainty of 8.4 Bq/kg（1s）.The reference samples did not contain any other artificial radionuclides,so the content was both appropriate and uniform.The results of a homogeneity test using one-way ANOVA analysis indicated that the standard deviation of 137Cs and 210Pb activity were 0.22 Bq/kg,2.10 Bq/kg,respectively,and the activity of 137Cs and 210Pb between the 3 proficiency test（PT） sample groups exhibited no significant differences at the 0.05 level,indicating relatively good uniformity.The PT samples have been distributed to six laboratories of IAEA cooperation projects in the Asia-Pacific region for proficiency test in 137Cs and 210Pb environmental radionuclides activity measurement,and the results showed good uniformity and stability in the PT samples.