Elemental groups separation for high-level waste partitioning using a novel silica-based CMPO extraction-resin

To facilitate the management of high-level liquid waste (HLLW) and minimize its long-term radiological risk in geologic disposal, we have proposed an advanced partitioning process by extraction chromatography using a minimal organic solvent and compact equipment to separate long-lived minor actinides (MA) and specific fission products (FP) such as Zr and Mo from nitrate acidic HLLW solution. The process consists of two separation columns packed with CMPO (octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide) extraction-resin for elemental groups separation and R-BTP (2,6-bis-(5,6-dialkyl-1,2,4-triazine-3-yl)-pyridine) extraction-resin for the isolation of MA from lanthanides (Ln), respectively. Several novel silica-based extraction resins have been prepared by impregnating CMPO or R-BTP into a macroreticular styrene- divinylbenzene copolymer which is immobilized in porous silica particles with a diameter of 50 μm (SiO₂-P). In this work, adsorption and elution behavior of typical FP elements from nitric acid solution onto the CMPO extraction-resin was investigated. Separation experiments for simulated HLLW solutions containing a trace amount of ²⁴³Am(III) and macro amounts of typical FP elements were carried out by column chromatography. It was found that the elements in the simulated HLLW were successfully separated to the following there groups: Cs-Sr-Rh-Ru, Pd-Ln-Am and Zr-Mo. (author)