Thermal Hydraulic Modeling of a Nuclear Reactor Core Channel Using CFD; Application for an EPR

An EPR (Evolutionary Pressurized Reactor) is a third generation nuclear reactor. It works at high temperature and high pressure and uses water as coolant and moderator. The coolant flow is axial between four cylindrical fuel rods, this configuration is the nuclear reactor core channel presented and studied here. The thermal-hydraulic nuclear reactor core channel analysis is done thanks to the conservation equations of mass, momentum and energy. Turbulence is modeled by the two equation model. The heat generation law, in the fuel, is introduced thanks to a User Defined Function (UDF) available in the used CFD code. Mesh of the numerical domain is done with Gambit and the set of equations is solved by finite volume method implemented in the code FLUENT. The mesh sensitivity is checked before resolving the problem. The application for an EPR’s thermal-hydraulic channel is presented. A parametric study is done. The evolutions of pressure, fluid temperature and clad temperature, for a sinusoidal behavior of the nuclear reactor power, are presented and commented. A comparison of the design temperature of the cooling fluid at the exit of the nuclear reactor core and the one calculated by CFD shows that the relative difference don’t exceed 3.3%.