CFD simulation of mixed convection and condensation in a reactor containment: the MICOCO benchmark

In the context of PWR reactor containment integrity studies, the MICOCO Benchmark (MIxed COnvection and COndensation) is organized to validate CFD codes by comparison with experimental data. The MISTRA facility of CEA provides experimental data. The case of a steam injection in a closed containment, initially filled with air, during the steady state is studied. Seven organizations performed semi-blind calculations (global data such as pressure and mean temperature of the containment wall were given) for this Benchmark with the multi-compartment containment code COCOSYS (GRS), with 'containment' CFD codes such as GASFLOW (FZK), GOTHIC 7.1 (NAI), GOTHIC 6.1b (AECL) and TONUS-V2002.D (CEA) and with general purpose commercial codes CFX4.4 (University of Madrid) or CFX 4.3 (PSI). Two-dimensional axi-symmetric results are presented, dealing with convective turbulent flow, in the presence of condensation. The simulations are compared to the experimental data during the steady state. Main phenomena, including stratification, temperature and steam concentration gradients, plume spreading and condensation rates at 3 levels are well represented by several participants. It is observed that proper modeling of the vessel heat loss is necessary to achieve a good representation of the gas temperature field