LES of the Flow Inside the Lower Plenum of an Advanced Gas-Cooled Reactor with Conjugate Heat Transfer

The details of flow and conjugate heat transfer in Advanced Gas-cooled Reactors are currently not completely understood because of the reactor complexity and the difficulty to examine the flow while the reactors are in operation. This paper proposes to simulate the flow using Large Eddy Simulation for the turbulence and to compute the conjugate heat transfer by coupling a multi-purpose CFD software with a transient thermal software dedicated to complex solid geometries. Two configurations are used, 1/8th of the full reactor and the full reactor itself. It is shown that simulating 1/8th of the domain only does not allow to reproduce the agitated patterns observed near the centre of the under-dome, where the temperature is the highest.