HIGH-EFFICIENCY DEHALOGENATION OF LICL-KCL BASED ELECTROREFINER SALT USING PROTONATED ULTRASTABLE Y-TYPE (USHY) ZEOLITE VIA ION-EXCHANGE

摘要

A dehalogenation process has been demonstratedthat can be applied to capture and recover radioactivehalogens such as 36Cl, 129I, and 81Br from molten salts.The process is based on ion-exchange between the saltcations and protons from dehydrated ultrastable H-Y(USHY) zeolite. The ion exchange reactions result in theremoval of the halogens in the form of HCl, HI, or HBrgas at 625°C. To recover I and Br, ion exchangeexperiments were run between USHY and eutectic LiCl-KCl salt, blended and melted with 5% NaI and 5% NaBr.A sampling of the solution and analysis by ICP-MSindicated about 60% of the original amount of both I andBr in the salt were recovered in an acid-base titrationcell. In our previous work, 95% Cl recovery has beenachieved in an ion exchange experiment between USHYand LiCl-KCl eutectic salt. Because of the long reactiontime needed to achieve high dechlorination efficiency,experiments were performed to identify the rate-limitingstep for dechlorination. The results of kineticsexperiments and post-test examination of samples indicatethat reaction is limited by the kinetics of the ion-exchangereaction. The reaction does not appear to be limited bydiffusion or mass transfer when using zeolite particleswith diameters of 45 μm or greater.