空气中氚的液体闪烁法测量条件优化  

Optimization of Measurement Condition for Determination of Tritium in Air by Liquid Scintillation Counting

作　　者：董传江[1,2] 苟家元[1,2] 蒲显恩 汤梦琪 吴耀 王雅洁 王鲁丰 陈灵珠 黎皖豪 李俊杰 高婧 DONG Chuanjiang;GOU Jiayuan;PU Xianen;TANG Mengqi;WU Yao;WANG Yajie;WANG Lufeng;CHEN Lingzhu;LI Wanhao;LI Junjie;GAO Jing(Sichuan Engineering Laboratory for Nuclear Facilities Decommissioning and Radwaste Management,Nuclear Power Institute of China,Chengdu 610213,China;Reactor Operation and Application Sub-institute,Nuclear Power Institute of China,Chengdu 610005,China)

机构地区：[1]中国核动力研究设计院,四川省退役治理工程实验室,四川成都610213 [2]中国核动力研究设计院,反应堆运行与应用研究所,四川成都610005

出　　处：《原子能科学技术》2023年第8期1658-1664,共7页Atomic Energy Science and Technology

摘　　要：为保护周围环境与公众,有必要监测反应堆周围环境空气中氚的活度水平。本文对空气中氚的测量条件进行了实验研究,测量了本底水和闪烁液对本底计数率的影响,研究了计数区间与样品-闪烁液配比对样品最低可检出浓度的影响。结果表明,选用Gold Star Quanta闪烁液、样品与闪烁液的配比为8∶12、计数区间为0.35~4.35 keV时,样品的最低可检出浓度最小。达到20 mBq/m^(3)的样品最低可检出浓度所需测量时间由31 h降低至16 h。During the operation of the reactor,a large amount of tritium is released into the surrounding air through the waste gas treatment system and the plant ventilation system.Tritium is very easy to replace hydrogen in water molecules,and can enter the human body through breathing,resulting in internal radiation hazards.Therefore,it is necessary to study the measurement of tritium in ambient air.At present,there is no national or industrial standard for the measurement of tritium in air.In this paper,the liquid scintillation counter was used to measure the activity concentration of tritium in air.It is found that the detection limit of the activity concentration of tritium in the air mainly depends on ambient temperature,relative humidity,sample amount,detection efficiency of the instrument,background count rate of the instrument,measurement time,etc.Among them,ambient temperature and relative humidity are inherent characteristics of air samples.Therefore,in order to reduce the detection limit and shorten the measurement time as much as possible,three aspects must be considered which is reducing the background count rate,improving the detection efficiency and increasing the sample volume.Possible approaches include selecting background water and scintillation fluid with the lowest possible counts,selecting the appropriate counting area,and optimizing the mixing ratio of sample and scintillation fluid.In order to reduce the effect of water and scintillation fluid on the background,11 different sources of background water and 3 types of scintillation fluid were selected for testing.The samples were prepared according to the ratio of 8 mL of water to 12 mL of scintillation fluid,and the long-term counting measurement was carried out after being stored in the dark for 24 h.The measurement results show that the count rate range of the background water sample varies from 2.373 min-1 to 3.441 min-1,and the difference between the maximum value and the minimum value is 1.068 min-1,which also shows that the selection of the ba

关 键 词：氚 空气 液体闪烁计数器 最低可检出浓度 计数区间 

分 类 号：TL75[核科学技术—辐射防护及环境保护]