Numerical modeling of an in-vessel flow limiter using an Immersed Boundary Approach

International audience; The increasing performance and safety requirements for the third generation of nuclear reactors led tonew Research and Development studies. In this context, new innovative systems are designed to preventor soften potential accidental or incidental situations. For instance, a passive system to postpone thecore dewatering, in the case of a Large-Break Loss Of Coolant Accident in Pressurized Water Reactors,has been imagined and patented by CEA. This passive flow limiter is composed of fins which, inaccidental behavior (for instance fluid coming out from the vessel due a break on the cold leg), force thecreation of a large vortex of fluid and so reduce the flowrate going outflow of the vessel (i.e. postponethe core dewatering). For more information about the background, the interested reader can refer to reference below.Of course, the pressure drop induced by the device (in both nominal and accidental situations) is greatlyinfluenced by the shape of the fins. Thus, in order to optimize its geometry, a fast and robust numericaltool, able to faithfully model the flow limiter, is needed.