Stability and radioactive gaseous iodine-131 retention capacity of binderless UiO-66-NH2 granules under severe nuclear accidental conditions

In the present work, we aim to investigate the ability of the zirconium-based MOF-type compound UiO-66-NH₂, to immobilize molecular gaseous iodine under conditions analogous to those encountered in an operating Filtered Containment Venting System (FCVS) line. Typically, the UiO-66-NH₂ particles were exposed to ¹³¹I (beta and gamma emitters) and submitted to air/steam at 120 °C, under gamma irradiation (1.9 kGy h^-1). In parallel to this experiment under simulated accidental conditions, the stability of the binderless UiO-66-NH₂ granules under steam and gamma irradiation was investigated. In order to fit with the specifications required by typical venting systems, and to compare the efficiency of the selected MOF to porous materials commonly used by the industry, scale-up syntheses and UiO-66-NH₂ millimetric-size shaping were realized. For this task, we developed an original binderless method, in order to analyze solely the efficiency of the UiO-66-NH₂ material. The shaped MOF particles were then submitted separately to gamma irradiation, steam and temperature, for confirming their viability in a venting process. Their structural, textural and mechanical behaviors were characterized by the means several techniques including gas sorption, powder X-ray diffraction, infrared spectroscopy and crushing tests. Promising results were obtained to trap gaseous molecular iodine in severe accidental conditions.