CFD Analysis on Hydrogen Risk in Subcompartment of the Containment

Hydrogen combustion in the containment building may be a threat to containment integrity. Especially in some subcompartments, local hydrogen detonation likely to happen, which may destroy the containment structure or the safety equipments in the containment. A study has been carried out using the GASFLOW three-dimensional CFD code to evaluate the hydrogen distribution in the subcompartment during a severe accident. The GASFLOW calculation has provided detailed results for the spatial distribution of gas concentrations in the reactor coolant pump (RCP) compartment and the steam generator (SG) compartment within containment, the high local hydrogen concentration was found in the local area. Then, three kinds of different hydrogen mitigation measures which were optimizing compartment structure, hydrogen recombiner and igniter were analyzed and compared. The σ criterion and λ criterion are used for conservative estimates of the flame acceleration (FA) potential and the possibility of deflagration to detonation transition (DDT) in the compartment after using the mitigation measures, respectively.