During severe accident oxidation of the metallic components of the reactor core and the core-concrete interaction will produce hydrogen which may threaten the integrity of the containment. It is important to predict hydrogen transport and mixing in the containment, in order to determine whether the mixture can locally reach flammability limits, and install the hydrogen mitigation devices at a reasonable and suitable position. Several turbulence models in FLUENT and GASFLOW were adopted in this paper to investigate hydrogen transport and mixing in the containment, and the results were compared. The study indicates that RNG k–ε model can obtain better simulation in parameter fluctuation, velocity field, and hydrogen concentration field than the other models’. The results calculated by algebraic model in GASFLOW are largely different from the other results in the simulation of mass diffusion, momentum diffusion, and parameter fluctuation. The results of k–ε model in GASFLOW have the similar trend as the results of FLUENT in velocity field and concentration field. Three hydrogen mitigation measures were also studied in a simple closed room using the code GASFLOW. The results indicate that the combination of recombiners and igniters is a safe and effective way to reduce the risk of hydrogen combustion.

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