Dispersed particle fuel is a new type of nuclear fuel that is in shape of small spheres and dispersed in a matrix. It has been widely used in advanced reactors such as high-temperature gas-cooled reactors (HTRs), space reactors and fluoride-salt-cooled high-temperature reactors. This study, taking an HTR and a space reactor as examples, developed a virtual lattice method based on the open-source Monte Carlo code OpenMC to speed up dispersed particle fuel criticality simulation. Parallel tests on the scale of 100000 cores was carried out on the Shanhe supercomputing platform. The keff
result of the HTR model agrees well with the Shidao-Bay nuclear power plant experiment, indicating that the code is of high accuracy. As for the performance of the code, results show that the virtual lattice model is of less memory footprint and higher computational efficiency than the original physical lattice model. The memory- and time-consumption of the HTR virtual lattice model are 0.2% and 82% of the physical lattice model respectively. And thanks to the simplification of geometry, the virtual lattice model is of higher parallel efficiency. For strong scalability, the parallel efficiency of the virtual lattice model with 10752 cores is 83.4% while that of the physical lattice model is 63.6%. And for weak scalability, the parallel efficiency of the virtual lattice model with 131600 cores is 83.1% while that of the physical lattice model is 66.1%.