环境气溶胶中90Sr分析测量的不确定度评定

⁹⁰Sr是高毒性的纯β放射性核素,其物理半衰期和生物半衰期长,环境气溶胶中的⁹⁰Sr通过吸入途径进入人体,对人类的危害主要为长时间积集在人体骨骼中并很难排出。在多堆型核设施运行场址中环境气溶胶的测定是辐射环境监测的重要内容,也是评价核设施运行对环境影响的重要指标。为了科学评价环境气溶胶中测量结果的准确性和可靠性,进行了气溶胶中⁹⁰Sr分析测量不确定度评定的方法研究,通过计算模型识别不确定度的来源,并对各分量进行量化分析,计算合成标准不确定度;结合典型样品分析实例,对环境气溶胶中⁹⁰Sr分析测量的不确定度进行了评定,气溶胶中的分析测量采用的是色层萃取的方法,利用草酸钇沉淀制成样品源,测量样品中β计数率。不确定度评定结果表明:环境气溶胶中⁹⁰Sr分析测量不确定度的来源主要有样品净计数率,探测效率,化学回收率,样品取样体积,测量期间半衰期修正;典型实例分析结果显示环境气溶胶中的相对标准不确定度可控制在15%内。文章中不确定度评定方法为气溶胶⁹⁰Sr分析测量结果的不确定度评定提供参考。

Uncertainty Evaluation for the Analysis and Measurement of90Sr in Environmental Aerosol

⁹⁰Sr is a highly toxic pure beta radionuclide with a long physical half-life and biological half-life.⁹⁰Sr in environmental aerosols enters human body through inhalation,and the main harm to human is that⁹⁰Sr is accumulated in human bones for a long time and is difficult to be discharged.For the multi reactor nuclear facility operation site,the measurement of environmental aerosol is an important content of radiation environmental monitoring,and is also an important index to evaluate the impact of nuclear facility operation on the environment.In order to scientifically evaluate the accuracy and reliability of measurement results in environmental aerosols,this paper studied the evaluation method of measurement uncertainty of⁹⁰Sr analysis in aerosol,and analyzed the various components of the calculation model by calculating the source of the uncertainty,and calculated the uncertainty of the synthetic standard.The uncertainty of⁹⁰Sr analysis and measurement in environmental aerosol is evaluated by combining typical sample analysis examples,the method of chromatography extraction is used for the analysis and measurement of aerosol,the sample source is made by yttrium oxalate precipitation,and theβcount rate in the sample is measured.The results of uncertainty evaluation showed that the main sources of uncertainty of⁹⁰Sr analysis and measurement in environmental aerosols include sample net count rate,detection efficiency,chemical recovery rate,sample volume,and the half-life correction during measurement.The analysis results of typical examples showed that the relative standard uncertainty of environmental aerosol can be controlled within 15%.The uncertainty evaluation method in this paper provides a reference for the uncertainty evaluation of aerosol⁹⁰Sr analysis and measurement results.