Adsorption Behavior of Cesium on Hybrid Microcapsules in Spent Fuel Solution

Hybrid microcapsules (H-MCs) are being developed for the column separation of Cs from high-level radioactive liquid waste (HLLW). In this paper, adsorption behavior of H-MCs has been evaluated by a batch method in single-element solution and a spent fuel solution prepared from irradiated MOX fuel. The spent fuel solution contain FPs and minor actinide (MAs), not containing U and Pu. Distribution coefficients ( K d ) of various metal ion including Cs were determined for three types of H-MCs (AMP-SG (silica gel enclosing ammonium molybdophosphate), AMP-ALG (calcium alginate gel enclosing ammonium molybdophosphate) and AWP-ALG (calcium alginate gel enclosing ammonium tungstophosphate)) in the spent fuel solution. The three types of H-MCs exhibited higher K d s for Cs than those for the other elements in spent fuel solution. The difference of K d for the specific element (Cs) and the other elements was larger than one order of magnitude. Therefore, chromatographic separation of Cs in the spent fuel solution using a column packed with H-MCs will be achieved. It was the similar tendency between the spent fuel solution and the single-element solution that the K d value for Cs of AWP-ALG was the largest among those of three gels. Thus, the mechanism of adsorption of Cs onto these H-MCs would not be changed in the presence of FPs and MAs. Therefore, these types of H-MCs can be effective for separation of Cs in the spent solutions.