Thermokinetic analysis of spent ion exchange resins for the optimization of carbonization reactor condition
Radioactive spent ion exchange resins, a combustible organic waste, cannot be readily incinerated due to the volatilization of radioactive cesium. The volatilization of metals and the thermal decomposition of organics are thermally stimulated processes. An optimum thermal treatment condition without the volatilization of cesium species but with the substantial decomposition of organics is required for a safe volume reduction of spent ion exchange resins. Using thermogravimetric analysis methods, this study established the optimum thermal treatment conditions for a substantial decomposition of spent resins with minimized volatilization of cesium species. Kinetic analyses and predictions of the complicated reaction steps involved in the thermal decomposition of spent cation exchange resins were conducted initially, with the results then used to establish the optimum thermal treatment conditions. Under these optimum conditions, nearly all of the cesium species in the spent resins were converted into thermally stable cesium sulfate (Cs2SO4) at temperatures up to 1000 degC. More than 97 of cesium species remained after the final burning out of the carbonized spent resins.
Journal of Thermal Analysis and Calorimetry