热湿传递作用下颗粒堆积型双重孔隙射气介质氡的迁移行为研究

Radon is one of the important carcinogens, mainly produced by the emanation media containing radium or uranium. The surface radon exhalation rate of the media is the key factor determining the radon concentration level in the atmosphere, and the influence of the heat-moisture transfer action and the pore structure characteristics on the radon transport and exhalation in the emanation media cannot be ignored. Taking the particle-packing dual-porosity emanation media existing extensively in uranium mines in China as the object, the project will study the variation rules of emanation coefficient and diffusion coefficient of radon of uranium ores, the radon release behavior in a single piece of uranium ore particle, and the equivalent release behavior and the diffusion coefficient variation rules of radon in the particle-packing dual-porosity emanation media under different heat-moisture conditions, to establish the equivalent release model and the diffusion coefficient prediction model of radon. Then, the radon migration behavior in the particle-packing dual-porosity emanation media under the heat-moisture transfer action will be studied, and the solubility equilibrium relationship of radon between the gas and the liquid and the dynamic model of heat-moisture transfer are coupled with the radon equivalent release model, to further build a coupled dynamic model and a numerical computation model of radon release-diffusion-advection in the particle-packing dual-porosity emanation media under the heat-moisture transfer action. Finally, a simulation software are developed, which realizes the dynamic simulation of the radon transport and exhalation process. This project will help to accurately predict and evaluate the surface radon exhalation rate of the particle-packing dual-porosity emanation media, and is of significantly theoretical value in optimizing the radon protection engineering.

氡是重要的致癌物质，来自于含铀镭的射气介质。介质表面的氡析出率是决定空气中氡浓度水平的关键因素，而热湿传递作用和孔隙结构特征对射气介质氡的运移和析出的影响不容忽视。本项目以我国铀矿山广泛存在的颗粒堆积型双重孔隙射气介质为对象，拟研究不同热湿环境下铀矿石射气系数和氡扩散系数的变化规律、单个铀矿石颗粒氡的释放行为以及颗粒堆积型双重孔隙射气介质内氡的等效释放行为及其扩散系数的变化规律，建立氡的等效释放模型及其扩散系数的预测模型；研究热湿传递作用下颗粒堆积型双重孔隙射气介质氡的迁移行为，将气液两相间氡的溶解平衡关系、热湿传递动力学模型和氡的等效释放模型相耦合，进一步建立热湿传递作用下颗粒堆积型双重孔隙射气介质氡的释放-扩散-渗流耦合动力学模型及数值计算模型；研发模拟软件，实现氡迁移与析出过程的动态模拟。它对准确预测和评价颗粒堆积型双重孔隙射气介质表面的氡析出率，优化氡防护工程有重要的理论价值。

氡是重要环境致癌物质之一，来自于含铀镭的射气介质。介质表面的氡析出率是决定空气中氡浓度水平的关键因素，而热湿传递作用对射气介质氡的运移和析出的影响不容忽视。本项目以我国铀矿山广泛存在的颗粒堆积型双重孔隙射气介质为对象，通过文献调研、理论分析、现场与室内试验以及数值模拟等研究方法，研发了同步确定颗粒堆积型多孔射气介质氡/钍气迁移参数的确定方法和装置，开展了不同热湿环境下铀矿石和铀尾矿砂的氡可运移产生率与扩散系数测定实验，提出了铀尾矿砂氡射气系数的BP神经网络预测模型;获得了铀尾矿砂可运移钍气产生率和扩散系数与含水饱和度的数学关系。采用气液氡溶解平衡实验确定了氡溶解度与温度和盐度的数学关系；采用理论分析和室内物理实验等方法研究了气液界面氡传质行为和水浸颗粒堆积型多孔射气介质氡迁移行为，确定了气液界面氡传输速率与风速的数学关系，获得了不同水位和风速条件下氡析出率的变化规律。设计并制作了颗粒堆积型双重孔隙多孔介质氡迁移模拟实验装置，研究了堆浸铀矿石在与化学溶液反应堆浸期间的氡析出规律。建立了不同热湿环境下颗粒堆积型双重孔隙射气介质氡的释放-扩散-渗流耦合动力学模型及氡析出率的计算模型，编写了计算程序；以铀尾矿砂、堆浸铀矿石和爆破铀矿石堆为对象，采用实验和数值计算相结合的方法研究了外部热湿源作用下颗粒堆积型双重孔隙射气介质氡的迁移与析出行为。采用CFD的方法模拟了复杂几何结构和边界条件的爆破铀矿堆和铀尾矿砂氡的迁移过程及氡浓度场，揭示了铀矿冶典型场所颗粒堆积型多孔射气介质氡的迁移行为。项目适当扩展了研究内容，开展了非水相流体（NAPL）污染土壤的氡迁移与析出规律、密实型多孔介质氡迁移参数确定方法及迁移规律的理论与实验研究。项目取得的研究结论与成果对准确预测和评价颗粒堆积型双重孔隙射气介质表面的氡析出率，优化氡防护工程有重要的理论价值。