基于颗粒破碎的氚增殖剂球床堆积性能演变规律研究

In the D-T magnetic confinement fusion reactor, tritium breeding blanket play an crucial role on the function of tritium self-sufficiency and energy extraction, which is the key component for the application of fusion energy. And the solid tritium breeder blanket is the prior choice for future fusion reactors. The lithium- based ceramic pebbles are mostly used as tritium breeder in the solid tritium breeder blanket, and the performances of the pebble beds will directly affect the tritium breeding performance and the energy extraction of the blanket...In this project, the research on the evolution law of the packing behaviors of the tritium breeder pebble bed based on the pebble breakage will be carried out.The crushing threshold and the broken characteristics of the tritium breeder pebbles will be analyzed by pebble crushing experiments. And the crushing criteria and the broken pebble models of tritium breeder pebbles based on mult-sphere model will be established. Then, by the pebble bed compression experiments and the X-ray micro-tomography, the crushing rate of tritium breeder and the broken pebble distribution in tritium breeder pebble bed will be analyzed under different compression loads and temperature conditions. Furthermore, the effects of pebble breakage on the pebble packing structures and the thermo-mechanical properties of pebble beds will be analyzed and be compared and verified with the results of DEM simulation. Finally, the evolution law of the macro-thermomechanical properties, the packing structures and the meso-stress distributions of the tritium breeder pebble beds will be investigated by the DEM simulations considering the pebble breakage, and some empirical models of the packing behaviors of the pebble bed will be established. The research results of the project will provide a new way to realize the safe and reliable operation of tritium breeder system of fusion reactors from the angle of improving the performance of tritium breeder and pebble bed.

在D-T磁约束聚变反应堆中，增殖包层承担氚增殖和能量提取两大主要功能，是实现聚变能应用的核心部件。固态氚增殖剂包层是未来聚变堆的首选方案。氚增殖剂多采用锂基陶瓷微球，其球床性能将直接影响氚的增殖性能和包层能量提取。.本项目开展基于颗粒破碎的氚增殖剂球床堆积性能演变规律的研究。通过微球压碎实验分析氚增殖剂微球的破碎阈值及破碎特征，建立氚增殖剂微球破碎准则和基于MSM方法的氚增殖剂微球多球破碎模型；通过球床压缩实验和X-ray显微层析分析不同压缩载荷和温度下氚增殖剂球床的破碎率和破碎颗粒分布，及颗粒破碎对球床堆积结构和热机械性能的影响，并与DEM模拟结果相互验证。最后，通过DEM分析基于颗粒破碎的压缩过程中球床宏观热机械性能、内部堆积结构和细观应力分布的演化规律，建立球床堆积性能的经验模型。项目研究结果将对如何实现聚变堆氚增殖系统安全可靠运行，从提高氚增殖剂球床性能的角度提供一种新的思路。

在磁约束聚变堆中，产氚包层是实现聚变燃料氚增殖和能量提取两大主要功能的堆内核心部件。在固态产氚包层中，主要通过包层内部的氚增殖剂材料实现氚的增殖，而氚增殖剂多采用锂基陶瓷颗粒堆积而成的固定球床，其球床性能将直接影响氚的增殖性能和包层能量提取。而在恶劣的聚变堆包层运行环境下，氚增殖剂会发生破碎、烧结、粉化等行为，进而影响氚增殖剂球床的堆积性能。因此，本项目针对聚变堆氚增殖剂球床开展了基于颗粒破碎的球床堆积性能演变规律的研究。通过微球压碎实验分析氚增殖剂微球的破碎阈值及破碎特征，阐述了微球破碎的影响因素，建立了基于多球的破碎模型和最大接触力破碎准则，并开发了颗粒破碎离散元模拟方法（PB-DEM）。此外，通过球床压缩试验和离散元模拟，分析了球床内部颗粒破碎特性和球床的堆积性能与热机械性能，阐释了球床内部的接触力分布特性、颗粒破碎率及破碎颗粒分布、球床应力-应变关系特性等；揭示了颗粒破碎条件下球床堆积性能和热机械性能的演变规律，建立了球床堆积性能与球床尺寸、颗粒参数、机械压缩特性等之间的经验模型。本项目研究结果将对聚变堆固态包层的设计和分析提供支撑和参考作用。.自本项目实施以来，共发表学术论文6篇，其中SCI/EI收录论文5篇，在国内外学术会议上做口头报告或墙报报告5次。通过本项目培养1名博士后和1名硕士研究生，均已出站或毕业，另引进1名在站博士后。此外，项目负责人在本项目研究成果的基础上申请并获得四川省自然科学基金资助项目1项。