Iodine mass transfer from xenon-iodine mixed gas bubble to liquid sodium pool, (II) development of analytical model

Abstract

Iodine mass transfer in a xenon-iodine mixed gas bubble rising through a liquid sodium pool is analyzed on the basis of a diffusion model applied to the first short stage just after the bubble generation and a convection model applied to the successive stage. In the diffusion model, production of sodium iodide aerosols and generation of the heat caused by the chemical reaction of iodine vapor and sodium vapor are taken into account in addition to the diffusion of vapor and aerosols and the heat conduction in a static spherical bubble. The diffusion of aerosols is composed of Brownian motion, thermophoresis and diffusiophoresis. In the convection model, the analysis is made for aerosol settling caused by inertial deposition, sedimentation and Brownian motion in an internal flow induced by a spherical cap bubble rising. Increase in the initial iodine concentration in the bubble is shown to enlarge the temperature difference across a region between the reaction front and the bubble surface and to enhance a contribution of thermophoresis to the aerosol diffusion through the region. The decontamination factor obtained from the calculation describes well a rapid increase at the first stage and a slow increase in the successive period, which are seen in measured decontamination factors, and suggests the breakup of the original bubble during rising through the pool. © 1996 Copyright Taylor Francis Group, LLC.