Development of a critical heat flux correlation based on an annular film dryout mechanistic model under the annular flow conditions

This study proposes a mechanistic model-based correlation for the critical heat flux to meet the practical requirements for the design and safety analysis of light water reactors. The correlation is based on an annular film dryout mechanistic model for a single tube, which needs numerical integration from the onset of annular flow to the dryout point, expressed as an explicit non-dimensional equation to ensure a wide applicable range of coolant conditions. The correlation predicts a critical heat flux for the annular flow region in the pressure range of 1-16 MPa, the mass velocity range of 500-3000 kg/m²s, and the thermal equilibrium quality range of 0.05-0.7. The prediction by the developed correlation agrees well with that of the existing mechanistic model without any numerical integration of the annular flow conditions. (author)