The occurrence of a steam explosion resulting from fuel coolant interaction poses a significant threat to the integrity of nuclear power plants when extremely high-temperature molten corium is released into the preflooded reactor cavity. The present study establishes and verifies a computational fluid dynamics (CFD) model by simulating the TROI steam explosion experiment.

The suggested model uses the Lagrangian method to simulate particles and adopts a secondary breakup model by which the particles are fragmented based on the critical Weber number. The increased number of fine particles, surface area growth, and the propagation of the explosion pressure wave following the triggering of the steam explosion are effectively simulated with the established model. The formation of steam flow and the subsequent breakup of particles are basically governed by the heat transfer between the corium particles and the cooling fluids. The mass distribution of particle sizes after breakup is obtained by modifying the main terms of the error function, which determines the diameter of child particles to be comparable with experimentally measured distributions.

With this modeling, the maximum pressure obtained by the simulation approaches the measured peak pressure. This suggests that the established CFD model is successful in describing the overall thermal-hydraulic phenomena during a steam explosion. In the future, the steam explosion CFD model will be further enhanced to obtain a more sophisticated model to minimize the uncertainty in steam explosion predictions.