无人机载CeBr3航空监测系统无限大面源探测能力研究

Research on the Detection Capacity of UAV-borne CeBr3 Monitoring System with Infinite Surface Source

在核设施发生重大事故后,快速获取事故应急区内的辐射水平,对后续应急决策及救援、保护公众免受辐射危害具有至关重要的意义,核应急航空辐射监测是核应急早期快速获取辐射水平的重要技术手段和方法之一,因此核工业航测遥感中心自主研发了无人机载CeBr3航空监测系统。为准确评估该监测系统的探测能力,文章使用蒙特卡罗方法对该监测系统进行了建模,并通过60Co点源对模型的准确性进行了验证。在此基础上,采用全能谱分析、蒙特卡罗及实验相结合的方法获得监测系统对天然辐射单位能谱,并以核事故后地面受到一个新的137Cs放射性沉降场景为例,计算监测系统在不同测量条件下(天然辐射本底、晶体体积、测量高度)对无限大137Cs面源的探测效率及最小可探测活度浓度。通过模拟及计算监测系统对天然辐射本底及核应急人工放射性核素的单位能谱,准确评估了自研的无人机载CeBr3核应急航空监测系统的探测能力,为后续利用该监测系统开展核与辐射航空监测可提供重要理论依据及数据支撑。

In case of a severe nuclear accident,it is critical to quickly obtain the radiation level in the accident emergency area for follow-up emergency decision-making and rescue,and to protect the public from radiation hazards.Airborne radiometric survey is one of the important technical means and methods to quickly obtain radiation levels in the early stage of nuclear emergency.Therefore,a UAV-borne CeBr3 monitoring system was designed and developed by Airborne Survey and Remote Sensing Center of Nuclear Industry.In order to evaluating the detection capability of the system,a Monte Carlo model was constructed and verified by a 60Co radioactive source.After that,the combination of full spectrum analysis,Monte Carlo and test were used to obtain the unit energy spectra of the monitoring system for natural occurring nuclide,and the detection efficiency and minimum detectable activity of the monitoring system against 137Cs infinity planner source were calculated and obtained under different monitoring conditions(natural radiation background,crystal number and measurement height)when the ground was subjected to a new 137Cs radioactive deposition.By simulating and calculating the unit energy spectra of natural radiation background and artificial radionuclide in nuclear emergency,the detection capacity of the self-developed UAV-borne CeBr3 monitoring system was accurately evaluated,which provided an important theoretical basis and data support for the subsequent use of the monitoring system to carry out airborne monitoring in nuclear emergency preparedness.