Characteristics of iodine removal by charcoal filter and their safety evaluation

There have been a number of studies no the removal of radioactive iodine using several kinds of adsorbents. However, there are few reports on the variation of removal efficiency with the time considering the saturation of iodine in the adsorbent. The adsorption rate has been often assumed to be controlled by the fluid film resistance, and the adsorption mechanism has been explained simply by neglecting the time dependence. This paper presents the iodine adsorption characteristics by a charcoal filter which are obtained from a numerical calculation, taking into account the diffusion process inside of a porous particle. As the result, the iodine concentration at the outlet of the charcoal filter could break through from a certain time and then change with the time variously depending on the operating condition. And it was found that the adsorption rate is controlled rather by the intraparticle resistance than by the fluid film resistance. (auth.)