Author(s): Bestion Dominique; Guelfi Antoine
Linked Author(s):
Keywords: Modelling two-phase Flow; CFD; Critical heat flux
Abstract: This paper presents and illustrates a multi- scale approach of nuclear reactor thermalhydraulic s. The NEPTUNE project aims at building a new two -phase multi- scale thermalhydraulic platform for nuclear reactor simulation. The system scale models the whole reactor circuit with 0D, 1D and 3D modules with a coarse nodalization. The component scale models components like the reactor Core or Steam Generators with a finer nodalization using a homogenization technique with a porosity concept. For some specific applications it was found necessary to add a two -phase CFD tool able to zoom on a portion of the circuit where small scale phenomena are of importance for design purpose or safety issues. Here the basic equations are still averaged like in RANS approach for single phase, but the space resolution is finer than in component codes. These three scales have to be coupled in order to simulate many reactor transients where both local effects and system effects play a role. In addition, two-phase Direct Numerical Simulation Tools with Interface Tracking Techniques are b e ing used for even smaller scale investigations for a better understanding of basic physical processes and for developing closure relations for averaged models. The multi- scale approach is presented and illustrated by the application to the investigations of the Critical Heat Flux in a Pressurized Water Reactor. Attention is focused on the two -phase-CFD development and validation.
Year: 2007