Very high temperature reactor (VHTR) is a Generation-IV (Gen-IV) type of reactor which could nominally operate at a high temperature. In traditional two-step core neutronics calculation method of VHTR, the high precision multigroup cross sections are required. Therefore, a new Monte Carlo based generation scheme for multigroup cross sections of pebble type VHTR, based on open source code OpenMC, is proposed in this paper. The new method can effectively deal with the double heterogeneity effect of pebble type VHTR. And the generated multigroup cross sections can be applied to the deterministic neutronics calculations and OpenMC multigroup calculations. Moreover, a unit cell model and a simplified pebble bed lattice model of VHTR were developed to be used for verification of the method. According to the verification results, the new developed method using OpenMC to generate multigroup homogenized cross sections for pebble type VHTR is feasible and enough accurate.

高温反应堆（VHTR）是IV代（Gen-IV）类型的反应堆，名义上可以在高温下运行。在传统的VHTR两步核心中子学计算方法中，需要高精度的多组截面。因此，本文提出了一种新的基于蒙特卡洛的卵石型VHTR多组截面的生成方案，该方案基于开源代码OpenMC。新方法可以有效地处理卵石型VHTR的双重异质性效应。所生成的多组截面可以应用于确定性中子学计算和OpenMC多组计算。此外，开发了VHTR的晶胞模型和简化的卵石床晶格模型，以验证该方法。根据验证结果，