环境水中氚浓度的液体闪烁计数测量方法及其质量控制  

Measurement Method of Tritium Concentration in Environmental Water Using a Liquid Scintillation Counter and Its Quality Control

作　　者：胡崇庆 赵超[1] 刘佳煜 HU Chong-qing;ZHAO Chao;LIU Jia-yu(Shanghai Institute of Measurement and Testing Technology,Shanghai 201203,China)

机构地区：[1]上海市计量测试技术研究院,上海201203

出　　处：《计量学报》2023年第11期1776-1782,共7页Acta Metrologica Sinica

基　　金：上海市市场监督管理局科技计划项目(2022-07);上海市计量测试技术研究院科技计划项目(H00RY2208)。

摘　　要：以一台超低本底液体闪烁计数器LSC-LB7为例,研究优化了其测量环境水中氚浓度的实验参数和测量方法,归纳总结出该仪器测定低水平氚浓度样品的暗处理时间、计数窗口等参数,有效地降低了液体闪烁计数器测水中氚浓度的探测下限。将已优化参数的测量方法与未优化的测量方法进行比较,结果发现未进行液闪参数优化的测量结果与优化参数的测量结果的相对偏差最大可达为33.87%,且优化后的测量方法可使水中氚浓度的测量不确定度改善50%。另外,为了获得适用于环境水样氚测量的猝灭校准曲线,研究自制了一套化学猝灭系列校准标准源,结合优化后的液闪测量方法,利用该猝灭校准曲线对环境水样进行测量,并与商用猝灭校准标准源的测量结果比较,两者结果相对偏差约11%。最终,基于优化后的液闪测量方法和自制标准源的猝灭校正曲线对该环境水样品进行测量,得到该环境水样中氚的活度浓度为(12.21±2.08)Bq/L,k=2。Taking an ultra-low background liquid scintillation counter LSC-LB7 as an example,the experimental parameters and measurement methods for measuring tritium activity concentration in environmental water were studied and optimized.The optimized experimental parameters such as dark treatment time and counting window were summarized,which can effectively decrease the detection limit of tritium measurement of water samples by this liquid scintillation counter.The optimized measurements were compared to those with unoptimized parameters,the results showed that biggest relative deviation of 33.87%between the two methods,and that the optimized method was able to reduce the uncertainty of the tritium concentration in water by 50%.With the aim of quenching calibration using the liquid scintillation counter to measure tritium activity concentrations in environmental,a series of self-made standard sources with different degrees of quenching and a consistent tritium activity concentration was counted in a sequence by optimized measuring method,and a quenching calibration curve was created.When the quenching calibration curve was used to measure the environmental water samples and compared with the commercially available standard sources for quenching,it was observed that the actual values were different and the relative deviation is about 11%.Finally,based on the optimized liquid scintillation measurement method and the quenching calibration curve of the self-made standard source,the activity concentration of tritium in the environmental water sample was determined to be(12.21±2.08)Bq/L,k=2.

关 键 词：环境水中氚 液体闪烁计数器 计数窗口 猝灭校准 不确定度分析 

分 类 号：TB98[一般工业技术—计量学]