Improvements in a CFD code for analysis of hydrogen behaviour within containments

The use of CFD codes for the analysis of the hydrogen behaviour within NPP containments during severe accidents has been increasing during last years. In this paper, the adaptation of a commercial multi-purpose code to this kind of problem is explained, i.e. by the implementation of models for several transport and physical phenomena like: steam condensation onto walls in presence of non-condensable gases, heat conduction, fog and rain formation, material properties and criteria for assessing the hydrogen combustion regime expected. The code has been validated against several experiments in order to verify its capacity to simulate the following phenomena: plumes, mixing, stratification and condensation. Moreover, two tests in an integral large enough experimental facility have been simulated, showing that the well-mixed and stratified conditions of the test were reproduced by the code. Finally, an example of a plant application demonstrates the ability of the code in this kind of problems.