In BWRs (Boiling Water Reactors), the fuel bundle's power distribution affects cooling and safety, particularly under high heat flux conditions seen in RBWR (Resource-renewable BWR) fuel bundles. This study focuses on understanding the critical power and liquid film dryout, where the liquid film evaporates during cooling. For accurate prediction of the dryout location, the entrainment of droplets from the liquid film due to nucleate boiling is essential for reactor safety. Ueda et al. showed that droplet entrainment is influenced by the vapor bubble velocity and liquid film thickness. Raka et al. identified two types of droplet entrainment: Jet-type and Filament-type, depending on heat flux. This study reveals a new type of entrainment mechanism called Wave-type, which is caused by shear forces from air flow and disturbances in the liquid film due to nucleate boiling. This mechanism has larger droplets and higher entrainment mass than other Jet-type and Filament-type mechanisms. Therefore, it is an important mechanism for predicting droplet entrainment. This study also found that the onset of Wave-type entrainment is affected by parameters such as heat flux, gas velocity, and liquid velocity. A prediction method for the onset condition was developed using dimensionless numbers. Additionally, a new prediction method for the boiling entrainment rate was proposed. At this time, the droplet entrainment mechanism is divided into Filament-type and Wave-type mechanisms, and correlations have been developed for each. This allows for evaluating the entrainment rate under both conditions.