固体裂变产物吸附沉积行为实验研究

It is an important project to understand and control the behavior of radioactive products for it relates to the nuclear safety. To accurately analyze the radioactive source term, to do the experimental study of the adsorption and deposition behavior of the solid fission products (Cs-137, I-131, etc.) in the primary system of the nuclear reactor, and to grasp their adsorption and deposition behavior from the basic principles of physical chemistry, are significant to the development of the nuclear science, the improvement of the reactor safety, and the implementation of radiation protection. Currently, most of the source term analysis methods and fission products data come from the early study abroad. Our research subject will be based on the 10MW high temperature gas-cooled test reactor (HTR-10) and a systematic radioactive experiments will be performed with the aim to study: (1) the kinds of the nuclides, the total and individual activities, and the chemical form of the solid fission products in the primary loop; (2) the adsorption and deposition behavior of the solid fission products on the surface of different materials; (3) the adsorption relationship between the solid fission products and the graphite dust particles, etc. The non-radioactive experiments (which use I-127 instead of I-131, etc.) will also be carried on for comparison. A more accurate theoretical model based on these experimental data will be presented which can explain the mechanism of the adsorption and deposition behavior of the solid fission products on the surface of different materials. To combine our research results with the knowledge in other fundamental science such as surface science, particuology and so on, a research approach of the solid fission products which mainly bases on the radioactive experiments will be constructed, and a large amount of important source term data will be supplied at the same time.

对核能系统中放射性物质行为的认识与控制是关系核安全的重要课题。准确分析放射性源项，开展反应堆上一回路固体裂变产物（Cs-137、I-131等）吸附沉积行为实验研究，从基础物理化学原理上掌握其吸附沉积规律，对核能学科的发展、反应堆安全性的提高、辐射防护的实施具有重要意义。目前国内核能领域的源项分析方法与裂变产物数据大部分来自国外早期研究结果。本课题将以清华大学10MW高温气冷堆为平台，通过一系列放射性实验研究一回路中固体裂变产物的种类、活度和化学形态、在不同材料表面的吸附沉积行为及与一回路石墨粉尘颗粒的吸附关系等，对比非放射性实验（I-127代替I-131等）研究，提出更为准确的理论模型，揭示固体裂变产物在多种材料上吸附沉积机理和一般规律，结合相关基础科学如表面科学、颗粒学等研究结果，为核能及相关学科建立一套以放射性实验为主的固体裂变产物研究方法，同时提供重要的源项实验数据。

核安全是保障核能健康持续发展的重要基础。很大程度上，核安全依赖于对核能体系中放射性物质行为的认识和控制。本项目以清华大学10MW高温气冷堆为平台，从放射性实验、非放射性实验和理论建模计算方面开展了针对固体裂变产物吸附沉积行为的综合研究。其中放射性实验测量是本项目的研究基础，也是最为重要和关键的部分。本项目主要完成了以下研究：（a）HTR-10一回路放射性测量实验研究；（b）HTR-10堆芯辐照后石墨球实验研究；（c）典型核素在石墨等材料中输运行为和放射性粉尘吸附沉积模拟计算；（d）模拟事故工况下非放射性石墨粉尘的沉积行为研究。本项目建立了一套以放射性实验为主的固体裂变产物研究方法，实验确定HTR-10一回路放射性粉尘活度浓度及典型核素比活度、冷却剂中氚和碳-14活度浓度、主要设备的外表面剂量率、辐照石墨球核素种类和分布等关键源项信息，开展第一性原理计算研究典型核素在石墨等材料上的吸附及扩散现象，利用非放射性石墨粉尘模拟事故工况下粉尘颗粒的沉积输运行为。本项目所建立的研究方法、获得的实验结果和开展的计算分析对我国高温气冷堆的辐射安全评价具有重要基础意义，已实际应用于国家科技重大专项高温气冷堆示范工程中，对国际球床式高温气冷堆固体裂变产物行为研究也具有重要推动作用。发表高水平学术论文12篇（SCI收录），会议论文4篇（EI收录），发明专利授权1项，申请发明专利8项（其中国际发明专利2项），受邀做大会报告、邀请报告等，培养研究生5名，获得清华大学实验技术成果奖一等奖和二等奖。