(315d) Adsorption of Iodine and Water on Molecular Sieve 3A

Iodine-129 and tritium are two major radioactive elements that are present in off-gases from spent fuel reprocessing plants. Adsorption by solid sorbents is the state-of-the-art technique for removal of these species from off-gases. Molecular sieve 3A (MS3A) is currently the best option for tritiated water removal. However, co-adsorption of iodine with tritiated water on MS3A is an issue that needs to be addressed due to significantly longer half-life of iodine (16M years) than that of tritium (12 years). This work focused on understanding adsorption isotherm and kinetics of iodine and water adsorption on MS3A. A continuous flow adsorption system was developed to gather accurate adsorption equilibrium and kinetic data. Adsorption data for iodine and water are being collected. These data will be used to develop advanced modeling tools for design of spent nuclear fuel reprocessing processes. Adsorption experiments are being conducted at 25-80 ^oC, water dew point from -70 to 20 ^oC, and iodine concentration from 0.3-25 ppm.  Preliminary results indicated that the capacity of iodine adsorption on MS3A is less than 1wt%, much lower than the maximum capacity of water adsorption on MS3A, which is around 21%. Adsorption isotherms and kinetics will be discussed in this presentation.