极低水平放射性废物测量系统模拟设计

Simulation Design of Very Low Level Radioactive Waste Measurement System

为满足放射性废物快速准确分拣和解控测量的需求,采用MC理论与实验结合方式设计了一套极低水平放射性废物测量系统。实验建立本底计数率与探测器人射窗面积的关系,以此推算拟设计系统存在10mm铅屏蔽下的本底计数率;利用152Eu放射源建立解控水平下最小可探测活度与钚γ射线发射率和系统计数率之间的关系。模拟研究与实验验证表明,设计系统的探测效率不低于30%,本底计数率低于10500s^-1;当测量时间为1000s,系统对15kg废物包的MDA优于300Bq/kg.

In order to meet the demand for the correct and fast classification of radioactive waste and free release detection,a very low level radioactive waste measurement system is designed basing on the combination of Monte Carlo simulation and experimental verification.The relationship between the background counting rate and the effective window area of the detector is established experimentally,so as to calculate the background counting rate of the proposed system under the condition of 10 mm lead shield;the relationship among the Y-ray emissivity of plutonium at the level of free release.the system counting rate and the lowest detectable activity(MDA)is established by using 1528 Eu radioactive source.Simulation research and experimental verification show that the efficiency of the proposed system is better than 30%,and the background counting rate is less than 10,500 s^-1;when the measuring time is 1000 s,the MDA of the system for a 15kgwaste package is better than 300 Bq/kg.