Study on Heat Transfer Characteristics of Irradiation Testing Fuel Assembly Discharged from Reactor and Dewatering Process

In order to establish a method to analyze the heat transfer characteristics of the fuel assembly after irradiation in the test loop of the research reactor, this study takes a PWR fuel assembly irradiated in the test loop of the High Flux Engineering Test Reactor (HFETR) as the object, simulates its discharge process and dewatering process after irradiation test by computational fluid dynamics (CFD), establishes a three-dimensional flow field and temperature field calculation model, and calculates their respective heat transfer characteristics. The results show that the maximum fluid temperature during discharging process is higher than the assembly outlet temperature. In the case of low room temperature, the heat dissipation of the dehydrated assembly is better, and the dehydration process can be carried out in advance. This method can calculate the maximum allowable time of the discharging process from the reactor and the cooling time required to achieve the dewatering condition. The method in this research can be applied to heat transfer characteristics analysis and prediction for the cooling process of fuel assemblies after irradiation in the test loop of research reactor.