Mechanical consequences of LOCA in PWR: Full scale coupled 1D/3D simulations with fluid–structure interaction

• We propose an approach to analyze the transient effects of LOCA on PWR internals.
• The complete primary loop is modeled using a coupled 1D-pipe/3D strategy.
• Full fluid–structure interaction is considered inside the main vessel.
• Impedance relations modeling the influence of small details are precisely calibrated.
• The capabilities of the 1D/3D methodology are demonstrated on a significant example.

The present paper is dedicated to the analysis of the fast transient mechanical consequences of the Loss Of Coolant Accident (LOCA) on the internal structures of a Pressurized Water Reactor (PWR). A complete methodology is described, based on a coupled 1D/3D representation of the entire primary loop of the reactor, with a robust and accurate approach for fluid–structure interaction inside the main vessel. A special attention is given to the modeling of small geometric details, such as perforated plates in the vicinity of the reactor core, through local impedance relations acting on the flow, which must be carefully calibrated for industrial purposes. The capabilities of the proposed framework are demonstrated with the application of the complete computational scheme to the simulation of the consequences of LOCA for a French 900 MW PWR, performed with EUROPLEXUS software.