Experimental and numerical study of a condensing steam jet

During a severe accident of a light-water reactor, a large amount of water vapor and hydrogen gas are generated, filling up the containment space. The hydrogen concentration in the containment space must be held below the flammable limit, even during a severe accident. The increase and decrease in the water vapor level may result in overpressure and elevation of the hydrogen concentration, respectively. Therefore, the risk of hydrogen in the containment building is closely related to the distribution and behavior of the water vapor. Condensation and evaporation change the concentration of the water vapor. A steam jet is one of the main water vapor condensation mechanisms during the early stages of accident scenarios. We investigated the flow features of the condensation of a steam jet experimentally as well as numerically. For different steam flow rates, flow characteristics induced by water vapor condensation were examined and certain flow features, in this case, the decay and spread of the velocity and temperature were studied. From the numerical study, it was found that a numerical simulation can accurately predict the condensation process from a macroscopic standpoint. (author)