Removal and Recovery of Ruthenium and Cesium from Spent Nuclear Fuel by Using Tungsten Molybdophosphate Novel Inorganic Ion Exchanger

Novel inorganic ion exchangers, tungsten molybdophosphate (WMP) and its silica-supported type (WMP-Si) were synthesized for the removal and recovery of elements from spent nuclear fuel. Both of ion exchangers were synthesized by vacuum impregnation method using a vacuum evaporator from phosphomolybdic acid and ammonium tungstate. The adsorption properties were evaluated by batch experiment in both HNO3 and HCl, as well as small-scale column test which carried out using Muromac® S-size column, and simulated high-level nuclear waste as feed in HNO3. The element concentrations before and after batch experiment and column test were evaluated using ICP-MS. In batch experiment results, it was confirmed that both WMP and WMP-Si had high selectivity towards ruthenium in low concentration of HNO3 and HCl, also strongly adsorbed cesium regardless of the acid concentrations. Small-scale column test also confirmed the adsorption of ruthenium and cesium at low concentrations of HNO3. On this test, it was confirmed that ruthenium was eluted and cesium remained in WMP-Si after washing with high concentration of HNO3, which means removal of cesium and recovery of ruthenium is possible by using WMP-Si. Furthermore, the adsorption capacity of ruthenium and cesium in were 0.65 mg Ru/g WMP and 2.38 mg Cs/g WMP respectively.