Investigation of hydraulic force of a 1000-MW pressurized water reactor under hypothetical drop accident of core barrel assembly

In this study, we conducted a simulation investigation of a hypothetical core barrel assembly drop accident based on the dynamic mesh model. The investigation included three separate circumstances: high-temperature dynamic water, high-temperature still water, and low-temperature still water. Results showed that dynamic parameters (e.g. velocity and resultant force) of the drop assembly in high-temperature dynamic water are smaller than those in still water due to the buffer effect of the flowing water. The velocity and hydraulic force in the dynamic water situation increased quickly at first and then remained stable throughout the remainder of the experiment; due to turbulence effect, the hydraulic force fluctuated slightly, first increased, then decreased, and then reached as stable a level in still water as that in dynamic water. The velocity of the drop assembly showed parabolic growth.