CFD Analysis of Iodine Mass Transfer Coupled with a Chemical Reaction in a Filtered Containment Venting System /

Abstract

Nuclear energy is considered as a zero-emission clean energy source. However, even though it can generate massive amounts of carbon-free electricity, potential accidents in nuclear power plants are a significant threat. Among these, the core meltdown is of significant concern. For environmental safety it is crucial to remove elemental radioactive iodine from flue gases through a system called FCVS (filtered containment venting system). Inside an FCVS, venturi scrubbers are significant, as they help remove the radioactive elements. Many studies have investigated the hydrodynamics of fluids inside venturi scrubbers and modelled the mass transfer of species between gases and scrubbing solutions. However, when it comes to modeling mass transfer coupled with a chemical reaction, the literature is very limited. Previous studies in literature have neglected the effect of chemical reaction on mass transfer. In this thesis, a UDF was developed to couple mass transfer of iodine and its reaction with Sodium Tetrathionate. The UDF was hooked to a commercial solver called Ansys Fluent, and CFD analysis was performed. The simulations were performed for three different gas flow rates and the resulting mass transfer enhancement was validated with experimental calculations present in the literature. The effect of droplet diameter on iodine removal efficiency was studied, and contours for mass fraction of iodine, thiosulfate, tetrathionate, and iodide along with hydrodynamics of the venturi scrubber were analyzed.