The need to limit the release of radioactive substances into the environment has always been a major issue in the field of radiation protection and the safety of nuclear installations. The expected reduction in discharge authorizations involves regular research and development efforts on improving existing processes or developing innovative processes, the effectiveness and safety of which must be demonstrated.A research effort based at the same time on means of characterizing the material constituting the iodine traps present in the installations, experimental means and modeling, will then make it possible to isolate from all the other mechanisms, the effectiveness of the mechanism. isotopic exchange of iodine in an adsorbent material. This mechanism is one of the retention mechanisms for radioactive iodine. To date, the very first tests have confirmed the importance of isotope exchange under certain operating conditions for the trapping of CH3I (127I + 131I) by commercial activated carbon. It is now a question of finely quantifying this contribution, initially, in model adsorbents synthesized to order, thus making it possible to isolate the contribution due to iodine compounds (KI or other derivatives) while being free from other mechanisms of retention. The simulation of breakthrough curves, based on known and controlled physicochemical characteristics of materials would also make it possible to overcome these simultaneous mechanisms. Ultimately, it is planned to describe isotopic exchange in a theoretical way and to implement it in this type of model so as to be able to predict the retention of iodine in a porous material of the activated carbon type. For this, “closed reactor” data will have to be acquired and modeled in order to characterize both the mass transfer phenomena (adsorption kinetics) and the adsorption equilibrium (sorption isotherms). these model materials will then be transposed to those found for commercial coals in order to be able to conclude as to the contribution of isotopic exchange in iodine traps conventionally used in nuclear installations. Ultimately, a safety coefficient encompassing this contribution must be proposed and subsequently taken into account during a "non-radioactive" test of iodine traps.