IODINE MASS-TRANSFER FROM XENON-IODINE MIXED-GAS BUBBLE TO LIQUID-SODIUM POOL .2. DEVELOPMENT OF ANALYTICAL MODEL

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 ap plied to the first short stage just after the bubble generation and a convection model applied to the successive stage. In the diffusion mod el, production of sodium iodide aerosols and generation of the heat ca used by the chemical reaction of iodine vapor and sodium vapor are tak en into account in addition to tile diffusion of vapor and aerosols an d the heat conduction in a static spherical bubble. The diffusion of a erosols is composed of Brownian motion, thermophoresis and diffusiopho resis. In the convection model, the analysis is made for aerosol settl ing caused by inertial deposition, sedimentation and Brownian motion i n an internal flow induced by a spherical cap bubble rising. Increase in the initial incline 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 thermophoresi s to the aerosol diffusion through the region. The decontamination fac tor obtained from the calculation describes well a rapid increase at t he 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.