一种小体积氡子体气溶胶调控装置的研制

A small volume radon progeny aerosol control device and its performance

为了满足国内外放射性气溶胶监测仪的氡子体气溶胶干扰量有效性校准的需求,基于气溶胶粒子与氡及其子体的行为规律,研制了小体积氡子体气溶胶调控装置,该装置包括气溶胶稀释回路、氡子体调控回路和可编程逻辑控制器(Programmable Logic Controller,PLC)控制系统的总控箱三部分,通过调控装置内的氡浓度、气溶胶粒子数浓度与换气率,能够输出氡子体状态参数稳定的氡子体气溶胶。实验结果表明,该小体积氡子体气溶胶调控装置可以实现的平衡当量浓度稳定调控范围为:3.3×10^(2)~9.4×10^(3) Bq·m^(-3),平衡因子的稳定调控范围为:0.12~0.58,未结合态份额的稳定调控范围为:1.4%~62.7%。在4 h内可以保证平衡当量氡浓度的变化范围在10%以内,均匀性实验相对标准偏差小于7%。氡子体关键参数的调控范围宽泛、氡子体空间分布的均匀性与稳定性较好,可以有效模拟现场测量环境,达到了装置的研制目的。

[Background]Nuclear sites require monitoring of artificial radioactive aerosols,but existing instruments often encounter the problem of"measurement uncertainty(radon progeny interference)"in the measurement of artificial radioactive aerosols,requiring effective calibration of radon daughter interference levels.[Purpose]This study aims to accurately calibrate the radon progeny measurement instruments and effectively calibratt the radon progeny aerosol interference levels for artificial radioactive aerosol monitoring instruments.[Methods]Based on the behavior patterns of aerosol particles and radon along with its progeny,a small volume radon progeny aerosol control device was developed,which was composed of aerosol dilution loop,radon progeny regulation loop,and controller with programmable logic controller(PLC)control system.In the aerosol dilution loop,varying concentrations of carrier aerosols was achieved by utilizing a circulating pump in conjunction with a aerosol generator.In the radon progeny regulation loop,different levels of radon sources were employed to achieve regulation of radon activity concentration.Radon progeny aerosol with stable radon progeny state parameters was achieved by adjusting the radon concentration,aerosol concentration and air exchange rate,and the performance of this device was verified by experiments.[Results]Experimental results show that the stable regulation range of equilibrium equivalent concentration(EEC)is 3.3×10^(2)~9.4×10^(3) Bq·m^(-3),stable regulation range of equilibrium factor:0.12~0.58,stable regulation range of unbound fraction:1.4%~62.7%.The variation range of EEC within 4 h is within 10%,and the relative standard deviation of the uniformity experiment is less than 7%.[Conclusions]The stable regulation range of the radon progeny state parameters of the small volume radon progeny aerosol control device proposed in this study is wide,and the uniformity and stability of the radon progeny are good.It can be used to effectively simulate the field measurement environment,achieving the development purpose of this device.