Effect of cation on HTO / H2O separation and dehydration characteristics of Y-type zeolite adsorbent

Several types of adsorbers have been studied as they are considered for the first stage of water detritiation systems processing more than 100 kg/h of high-level tritiated water generated in a future fusion plant. Zeolite is a suitable adsorbent since it is an inorganic material having a large water capacity. Rapid dehydration characteristics as well as a large HTO/H2O separation factor is necessary for the adsorber to minimize its size. Present experiments were focused on the effect of cations on HTO /H2O separation and dehydration characteristics of Y-type zeolites. The selected cations are Na, K and Ca. The framework SiO2/Al2O3 ratio of the zeolites is fixed to 5.0 in the present experiments. It was found that the isotope separation factors are around 1.1-1.2 under static conditions. As for dehydration, operating temperature fixes the capacity of movable water from the zeolites. The capacity at room temperature is NaY > CaY > KY. HTO dehydration characteristics depend on the accumulated purge gas amount, while the purge gas rate is less influential. Effect of temperature on HTO dehydration is also less influential especially in the early stage of dehydration. Pressure swing is an effective method for HTO dehydration. (authors)