水体在线放射性测量系统阵列溴化铈闪烁探测装置优化

Optimization of array CeBr_(3) scintillation detection device for water on-line radioactivity measurement system

为了能够提高水体在线放射性测量系统的探测效率以及降低探测下限,针对一种水体在线放射性测量系统的阵列溴化铈闪烁探测装置进行了优化设计。首先采用蒙特卡罗方法分别对探测器个数以及排列方式进行了仿真研究,结果表明:将三个Φ45 mm×50 mm溴化铈探测器以“品”字型紧贴的形式摆放,能够达到对^(137)Cs放射源的最小可探测活度浓度达到了为0.1 Bq·L^(−1)的设计标准有效降低系统探测下限。然后同时,采用“品”字型探测器布局的水体在线放射性测量系统对四川某河流域水体进行了连续监测,结果表明:该系统能够有效地监测水体中总α/总β的活度浓度以及^(238)U、^(232)Th和^(40)K的活度浓度变化情况。

[Background]With the vigorous development of the nuclear industry and the widespread application of nuclear technology,the radioactivity of inland water has become one of the key objects of radiation environmental monitoring.CeBr_(3)scintillation detector is one of candidates for water on-line radioactivity measurement system,but its detection efficiency is not high enough.[Purpose]This study aims to improve the detection efficiency of the water on-line radioactivity measurement system by optimization of array CeBr_(3)detector layout,and reduce the detection limit.[Methods]Firstly,calculate the optimal number of detectors in the system according to the minimum detectable activity concentration formula was calculated.Then,the Monte Carlo method was used to simulate the number and arrangement of Φ45 mm×50 mm CeBr_(3)array detectors to obtain optimized arrangement of detectors.Finally,the water on-line radioactivity measurement system with optimized layout of array CeBr_(3) detectors was applied to continuous monitoring of the water bodIES of a river basin in Sichuan province.[Results]The simulation results show that the three CeBr_(3)detectors placed in triangular arrangement and close to each other achieve a minimum detectable activity concentration of 0.1 Bq·L^(−1) for ^(137)Cs radioactive source,meeting the design standard of system detection limit.[Conclusions]The monitoring results show that the system can effectively monitor the variations of radioactivity concentration of totalα/βand ^(238)U,^(232)Th and ^(40)K in the water.