S. Miyahara et N. Sagawa, IODINE MASS-TRANSFER FROM XENON-IODINE MIXED-GAS BUBBLE TO LIQUID-SODIUM POOL .2. DEVELOPMENT OF ANALYTICAL MODEL, Journal of Nuclear Science and Technology, 33(3), 1996, pp. 220-228
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.