Abstract In solid tritium breeder blanket, the packing structures of the tritium breeder pebble bed and the neutron multiplier pebble bed are very important to analyze the tritium breeder ratio and the heat and mass transfer process in the pebble bed. In this study, the numerous simulations were conducted to investigated the effects of bed dimension, friction coefficient between pebbles, pebble size distribution and pebble density on the packing structures of the ceramic tritium breeder (Li4SiO4, Li2TiO3) pebble beds and the neutron multiplier (Be, Be12Ti) pebble bed by discrete element method (DEM), respectively. The simulation results reveal that the pebble bed dimension, friction coefficient and pebble size distribution have a significant impact on the pebble bed packing fraction. As the width of the pebble bed container increases, the average packing fraction of the pebble bed gradually increases, meanwhile the influence of volume fraction of the wall effect gradually decreases. In addition, a lower friction coefficient between pebbles (smoother surface of the tritium breeder and the neutron multiplier pebbles) and wider pebble size distribution will result in a higher packing fraction of the pebble bed. However, the material density of the ceramic tritium breeder (Li4SiO4, Li2TiO3) pebbles and the neutron multiplier (Be, Be12Ti) pebble seems to have no obvious effect on the packing fraction of the wider pebble bed for the solid tritium breeder blanket.

中文翻译：

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床层尺寸、摩擦系数和卵石粒径分布对固体氚增殖毯卵石床填料结构的影响

摘要 在固体氚增殖层中，氚增殖球床和中子倍增器球床的填料结构对于分析氚增殖比和球床传热传质过程具有重要意义。在这项研究中，进行了大量模拟以研究床尺寸、卵石之间的摩擦系数、卵石尺寸分布和卵石密度对陶瓷氚增殖剂（Li4SiO4、Li2TiO3）卵石床和中子倍增器（Be , Be12Ti) 球床分别采用离散元法 (DEM)。模拟结果表明，球床尺寸、摩擦系数和球床粒径分布对球床充填率有显着影响。随着卵石床容器宽度的增加，球床的平均填充率逐渐增加，同时壁效应体积分数的影响逐渐减小。此外，卵石之间较低的摩擦系数（氚增殖剂和中子倍增器卵石的光滑表面）和更宽的卵石尺寸分布将导致卵石床的填充率更高。然而，陶瓷氚增殖物（Li4SiO4、Li2TiO3）卵石和中子倍增器（Be、Be12Ti）卵石的材料密度似乎对固体氚增殖物毯的较宽卵石床的填充率没有明显影响。卵石之间较低的摩擦系数（氚增殖剂和中子倍增器卵石的表面更光滑）和更宽的卵石尺寸分布将导致卵石床的填充率更高。然而，陶瓷氚增殖物（Li4SiO4、Li2TiO3）卵石和中子倍增器（Be、Be12Ti）卵石的材料密度似乎对固体氚增殖物毯的较宽卵石床的填充率没有明显影响。卵石之间较低的摩擦系数（氚增殖剂和中子倍增器卵石的表面更光滑）和更宽的卵石尺寸分布将导致卵石床的填充率更高。然而，陶瓷氚增殖物（Li4SiO4、Li2TiO3）卵石和中子倍增器（Be、Be12Ti）卵石的材料密度似乎对固体氚增殖物毯的较宽卵石床的填充率没有明显影响。