Study on Prediction Models Development for Calculation of Reflooding Phase of Tight Lattice

Reflooding is the most important and complex process in a LOCA transient.Compared with ordinary PWRs,the reflooding phase of tight lattice has the characteristics of higher peak cladding temperatures and slower quench front rates.The existing best estimate codes could not be used for the reflooding calculations of tight lattice.Based on RELAP5,we developed a modified reflooding model,and did validations using experimental results and other researchers’ results.It is proved that the modified code could be used to model the reflooding phase of tight lattice.Further investigations are needed on the development of interfacial drag and interfacial heat transfer models of the dispersed flow region and the region just downstream of the quench front.