液闪法测量尿氚的不确定度评估

目的 尿液中氚的浓度是核设施工作人员受氚内照射污染严重程度的重要指标,对尿氚分析结果进行不确定度评价,能为相关国家标准的修订提供参考。方法 以液闪法检测尿氚为例,通过样品前处理、尿氚的测量和活度浓度的计算,对尿氚分析不确定度来源、数学模型的建立、标准不确定度的合成、不确定度分量和扩展不确定度的分析计算进行了探讨。结果 4个样品尿氚的相对不确定度分别为11.5%、18.2%、17.5%和20.9%,尿氚分析结果分别为(6.2±1.5) Bq/L、(3.8±1.4) Bq/L、(3.9±1.4) Bq/L、(3.2±1 4) Bq/L。结论 β计数统计误差为尿氚分析不确定度的主要来源。

Uncertainty Evaluation for Determination of Tritium in Urine Samples with Liquid Scintillation Counter

Objective Concentration of tritium in urine is an important indicator which can reveal the severity of tritium polltion to staff working in nuclear facilities. Uncertainty evaluation for analysis results of tritium in urine can provide a reference for revision of the national standards.Methods In this work, four real urine samples were taken as examples, the process of tritium determination with liquid scintillation counter, including sample preparation, measurement and calculation of radioactivity, were discussed. Additionally, uncertainty evaluation for tritium analysis in urine was performed. The origin of uncertainty, establishment of mathematical model, calculation of uncertainty were also detailed in this paper. Results The results showed that the relative uncertainty of the four urine samples were 11.5%、18.2%、17.5% and 20.9%. The tritium radioactivity of four samples were(6.2±1.5)、(3.8±1.4)、(3.9±1.4)、(3.2±1.4) Bq/L,respectively. Conclusion The uncertainty mainly originated from statistical error of beta counting.