摘要
放射性氙监测是禁核试核查现场视察和核设施安全监测的重要项目之一,能够快速准确地甄别违约核活动和预警识别核设施的泄漏。本文综合运用超低温动态吸附、中空纤维膜除杂和现场低本底测量等技术,研制了一套放射性氙高灵敏度现场快速自动化监测系统,用于放射性氙现场取样、分离和测量。测试结果表明,该系统在氡浓度为20 Bq/m^(3)、采样体积为2 m^(3)、分析周期不大于120 min时,氙回收率为79.9%,对^(133) Xe的最小可探测活度浓度(MDC)小于0.26 Bq/m^(3),测量结果的不确定度小于±12%。该系统具有灵敏度高、分析周期短、全流程自动化的特点,能够应用于核设施安全监测、现场视察放射性氙监测、核应急放射性气体监测等场合。
For the purpose of the peaceful,safe and reliable application of nuclear technology,the monitoring of radioactive gas is one of the most important items for on-site inspection of CTBTO and safety monitoring of nuclear installations,which could rapidly and correctly discriminate nuclear activity of violation treaty of CTBT(Comprehensive Nuclear-Test-Ban Treaty)and identify the leakage of nuclear installations.Since radio-xenon isotopes(mainly ^(131m,133,133m,135) Xe)have distinguished features including high fission yields,leaking easily and spreading worldwide,notable decay properties and low ambient concentrations,which are seen as important monitoring objects.Based on the proposed principle combined with these techniques including dynamic adsorption at-110℃ultra low temperature,impurity removal with hollow fiber membranes,and gamma spectrum monitoring with low background,a rapid and highly sensitive on-site automatic monitoring system for radioxenon was developed,which could sample,separate and measure radioxenon on-site with a rapid and efficient way.During the development process,the technological flow diagram for whole system was established,and the critical hardware components including impurity removal column,adsorption column,lead shield chamber,and sample container were designed.And then these elements were assembled as four modules about sampling,preprocessing,refrigeration and measurement units combined with other components such as three hollow fiber membranes,four flowmeters,two pressure sensors and a HPGe detector and so on.Meanwhile,two control softwares including upper computer and off-line control versions were designed.And the methods of efficiency calibration,recovery test,calculation of activity concentration and MDC(minimum detectable activity)of xenon,and uncertainty evaluation were studied.Then these parameters were tested including detection efficiency,recovery of stable xenon,MDCs of 133 Xe and 135 Xe,and uncertainties of measuring results.The experimental results show that the recovery of stable xenon is 79.9%,the MDC of 133 Xe is less than 0.26 Bq/m^(3)within a 120 min cycle including sampling,enrichment and measurement,when the activity concentration of 222 Rn and sampling volume are 20 Bq/m^(3)and 2 m^(3),respectively.Compared with technical specifications of other systems,the elapsed time of a cycle of the system developed in this paper decreases larger than 10 times of SAUNA-OSI and XESPM-Ⅲsystems,while the MDC of the systems is smaller than other rapid systems.Because this developed system has following features about high sensitivity,shorter monitoring period,automation during total process,it will provide a dominant and straightforward contribution to the on-site inspection(OSI)of CTBT,safety monitoring of the gaseous effluents and emergency monitoring for nuclear facilities,and will be a powerful supplement for current monitoring technique and systems.
作者
龙斌
周国庆
田言杰
雷卫国
陈伟
苏川英
王雪梅
冯淑娟
LONG Bin;ZHOU Guoqing;TIAN Yanjie;LEI Weiguo;CHEN Wei;SU Chuanying;WANG Xuemei;FENG Shujuan(Northwest Institute of Nuclear Technology,Xi’an 710024,China)
出处
《原子能科学技术》
EI
CAS
CSCD
北大核心
2024年第2期481-488,共8页
Atomic Energy Science and Technology
关键词
放射性氙
高灵敏度
快速
现场
自动化监测
radioxenon
high sensitivity
rapid
on-site
automatic monitoring
