Removal of zirconium from spent fuel solution by alginate gel polymer

Abstract

The uptake behaviour of zirconium (Zr) in alginate gel polymer and removal of Zr from spent fuel solution have been studied by the batch and column methods. As a first step, alginate gel polymer was synthesized and conditioned. The uptakes of Zr were examined in several concentrations of HNO3 solution (from 0.01 M to 9 M HNO3) by a batch method. Stronger affinity of Zr was shown than strontium (Sr), cobalt (Co), uranium (U) and iron (Fe) in 1 M HNO3. It has been reported that cation binding was stronger with ions of higher charge in the alginate gel polymer. In contrast, the free aqueous ion, Zr4+, is the dominant form of the Zr species in very acidic solution. Therefore, the strong affinity of Zr is explained. The uptake rate of Zr was also evaluated in 2.6 M HNO3 solution, which was close to the HNO3 concentration in actual HLLW from fuel reprocessing. The uptake of Zr reached equilibrium within 2 h. For the column experiment, fission products (FPs) solution containing rare earth elements (REEs), platinum group metals, alkaline metals, alkaline earth metals and the other elements was prepared from actual spent fuel and the concentration of HNO3 was adjusted to 2.6 M. In the column experiment, the alginate gel polymer was packed into a column, and then a chromatographic experiment was performed using the FPs solution prepared from actual spent fuel. As a result, over 95% of the Zr was removed from the FPs solution. Molybdenum (Mo), technetium (Tc), yttrium (Y), palladium (Pd), tellurium (Te), cesium (Cs) and REEs were eluted by the successive use of H2O, and 1 M and 3 M HNO3.