The Steam Generator is a key component of a Pressurized Water Reactor (PWR). It allows the heat exchange between the primary and the secondary circuit and transforms the water from the secondary circuit into steam, which then makes the turbines rotate.

The steam generator contains a large amount of water and the water level control is crucial. Indeed, a too high level of water may lead to the presence of liquid water droplets in the turbine area and damage it; and a too low level of water would prevent a proper evacuation of the residual power in the event of an incident. Water level oscillations on wide range sensors of steam generator have been detected on some PWR.

This report briefly recalls this issue and proposes a CFD approach to investigate a possible cause. As URANS calculations were not accurate enough to recover the full fluctuations experimentally observed, higher fidelity CFD approaches (LES/DES) are deployed for the current study for quantifying the unsteady phenomena developed and observed in the experimental setup.