Abstract
Under the severe accident of the nuclear power plant, hydrogen-steam mixture gas will be released into the containment compartments. In this process, there is a strong coupling relationship between mixture gas diffusion and steam condensation on the compartment wall surface. Especially for local compartments with poor connectivity, steam condensation is likely to aggravate the risk of hydrogen accumulation and combustion. This coupling phenomenon, which has not been systematically studied in previous numerical simulations or experiments, is especially complex and needs to be further studied. Moreover, the applicability of mechanistic numerical models for predicting condensation-induced transient gas transport processes also should be further confirmed. In this study, the mechanistic numerical model was evaluated through the transient hydrogen mixing experiment of the THAI facility. Based on the validated model, the transient mass transfer process of the mixture gas induced by condensation in a typical single compartment during the steam-hydrogen release process is studied. Furthermore, the influence of release condition of gas source term, wall sub-cooling on the hydrogen accumulation phenomenon in the compartment was discussed. The conclusion is helpful to further understand the transport behavior of hydrogen-air-steam mixture gas in the local single compartment under the severe accident.
