CFD - Application to reactor safety problems with complex flow regimes

The present paper deals with CFD-computations of two phenomena related to containment and environment safety: Containment thermal hydraulics including wall condensation and hydrogen deflagration in multiple-room containment geometries. Turbulent transient flow of air-steam mixture in the ThAI vessel (60 m3) at Becker Technologies is computed with STAR-CD. Conjugate heat transfer and wall condensation including liquid film dynamics are simulated. Physical models employed are discussed. Simulation requires extensive user coding to incorporate these models. Based on this experience and the status of some of the lumped parameter containment codes some features to be desired in commercial CFD-codes from a user point of view are presented. This work is part of a benchmark exercise where different CFD-codes are applied to a scenario which is measured in the ThAI vessel. Premixed combustion of hydrogen-air mixture in presence of steam in geometries with 1 to 4 rooms is simulated with own CFD-code BASSIM. Combustion model employed has been optimised based on comparison of calculation results with data from over 30 different experiments performed in Battelle Model Containment and other facilities of different sizes. Typical results of calculations are presented including the influence of scaling. (author)