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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。
Purpose The concentration of tritium in urine is an important indicator of the severity of pollution caused by irradiation of tritium in nuclear facilities. The evaluation of the urinary tritium analysis uncertainty can provide reference for the revision of relevant national standards. Methods Taking urine tritium for example by liquid scintillation method, the sources of uncertainty of urine tritium analysis, the establishment of mathematical model, the synthesis and uncertainty of standard uncertainty were analyzed by sample pretreatment, urine tritium measurement and activity concentration calculation The analysis and calculation of degree component and extended uncertainty are discussed. Results The relative uncertainty of urinary tritium was 11.5%, 18.2%, 17.5% and 20.9% respectively in the four samples. The urinary tritium analysis results were 6.2 ± 1.5 Bq / L, 3.8 ± 1.4 Bq / L and 3.9 ± 1.4) Bq / L, (3.2 ± 1.4) Bq / L. Conclusion The statistical error of β count is the main source of uncertainty of urine tritium analysis.