烟羽辐射模拟装置的研制及测试

Development and Test of a Radioactive Plume Simulator

环境γ监测设备对小剂量率变化的灵敏度是评价其辐射特性的一项重要指标。本文介绍了一种自行研制的烟羽辐射模拟装置,该装置由137Cs放射源及其传动系统、铅屏蔽体、不同厚度的铅衰减环、控制单元等组成。利用蒙特卡罗模拟和G(E)函数法对距离装置放射源3 m、离地面1 m高度处的空气比释动能率进行了计算,由上述两种方法得到的结果相对偏差在5%以内。结果表明,此烟羽辐射模拟装置在装载MBq量级的137Cs源时,预计可提供10 nGy/h^50 nGy/h的辐射场,可用于环境γ监测设备对小剂量率变化的灵敏度测试。

The response to small dose variation is an important performance indicator for environmental γradiation monitor. This paper introduces a radioactive plume simulator and the test result for its radiation field dose rate. The components of this device include a137Cs source and its transport system,source shieldings,lead attenuators of different thickness,and a controller system. The air Kerma rate at 3 m from the radiation source and 1m above ground was obtained by MC simulation and G( E) function method,and the difference between two method is within 5%. This device can provide a radiation field over the range of 10 nGy /h—50 nGy /h,when loading the MBq grade137Cs radioactive source,can be used to testing the performance of response to small dose rate variation for environmental γ radiation monitor.