Thermal Behavior of a MOX 1300 MWe Assembly While Lifted in Air before being Immersed into a Spent Fuel Pool

The deployment of MOX fuel assemblies in some of the 1300 MWe plants of the EDF nuclear fleet is under preparation as part of the French strategy concerning the closure of the nuclear fuel cycle.The present paper addresses the thermal aspects related to the handling of MOX fuel assembly when extracted from a MX6 transport cask and put into the spent fuel pool prior to its loading in the reactor core.The assembly, suspended vertically in an air atmosphere, is transferred from the preparation pit up to the spent fuel EDF pool where is it finally immerged.A conjugate heat transfer approach based upon the coupling of a finite volume CFD code (Code_Saturne) and a finite element thermal code (SYRTHES) takes into account all the heat exchange mechanisms (convection, conduction and radiation) to obtain the assembly temperature distribution during the transfer through the air to assess the mass of vapor generated during the immersion phase simulated using a simplified approach and validated against three experiments.