Abstract Nuclear graphite that can be used in molten salt reactors, one of the main types of fourth-generation nuclear reactors, has the properties of high purity, high density, and radiation resistance, and it also has a special pore structure that prevents infiltration of the molten salt fuel. The nuclear graphites IG-110, NBG-18, and NG-CT-50 were characterised using X-ray computed tomography (CT) to understand their internal pore structures. The porosities, isolated pore volumes, and connected pore volumes were obtained. The average diameter of connected pores in IG-110, NBG-18, and NG-CT-50 were 9.9, 10.4 and 9.5 μm, respectively, but the nuclear graphite NBG-18 had the broadest diameter range for connected pores, with many of > 25 μm. To further analyse the connected pores, pore throat networks were established based on the connected porosities. The pore throats, channel lengths, and coordination numbers of the connected pores were herein quantitatively analysed. Among IG-110, NBG-18, and NG-CT-50, the average diameters of the throats were 4.5, 5.2, and 4.6 μm, and the peak throat diameters were 1.8, 2.6, and 1.2 μm, respectively, but the NBG-18 pore throat distribution also included multiple peaks at larger diameters (16–20 μm), which was consistent with findings from the mercury intrusion test. Our statistics based on the pore throat networks suggested that NBG-18 is the most easily infiltrated by molten salt among the three nuclear graphite samples, while NG-CT-50 is the most difficult. The quantitative information from the pore throat modelling could be a basis for future studies on liquid flow simulations inside graphite. Graphic Abstract

中文翻译：

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通过同步加速器计算机断层扫描获得的核石墨的孔结构

摘要 可用于熔盐反应堆的核石墨是第四代核反应堆的主要类型之一，具有高纯度、高密度、耐辐射等特性，并具有特殊的孔隙结构，可防止渗入。熔盐燃料。使用 X 射线计算机断层扫描 (CT) 对核石墨 IG-110、NBG-18 和 NG-CT-50 进行表征，以了解其内部孔隙结构。获得孔隙率、分离的孔体积和连接的孔体积。IG-110、NBG-18 和 NG-CT-50 中连通孔的平均直径分别为 9.9、10.4 和 9.5 μm，但核石墨 NBG-18 的连通孔直径范围最广，具有许多> 25 微米。为了进一步分析连接的孔隙，基于连通的孔隙度建立了孔喉网络。定量分析了连通孔隙的孔喉、通道长度和配位数。在 IG-110、NBG-18 和 NG-CT-50 中，喉部的平均直径分别为 4.5、5.2 和 4.6 μm，喉部的峰值直径分别为 1.8、2.6 和 1.2 μm，但 NBG -18 孔喉分布还包括较大直径（16-20 μm）处的多个峰，这与压汞试验的结果一致。我们基于孔喉网络的统计表明，在三种核石墨样品中，NBG-18 是最容易被熔盐渗透的，而 NG-CT-50 是最难渗透的。来自孔喉模型的定量信息可以作为未来研究石墨内部液体流动模拟的基础。图形摘要