Fundamental Chemistry of the Universal Extractant (UNEX) for the Simultaneous Separation of Major Radionuclides (Cesium, Strontium, Actinides, and Lanthanides) from Radioactive Wastes

4 Scientists at the INEEL and KRI collaboratively developed and validated the concept of a Universal Extractant (UNEX) for simultaneously removing the major radionuclides (Cs, Sr, actinides and lanthanides) from acidic radioactive waste in a single solvent extraction process. The UNEX solvent incorporates three active extractants: chlorinated cobalt dicarbollide, polyethylene glycol and a carbamoylmethylphosphine oxide derivative, dissolved in a suitable organic diluent to simultaneously extract target radionuclides. The process chemistry is unique, but complicated, since the extractants operate synergistically to extract the radionuclides. Results indicate that water dissolved in the organic phase dramatically impacts the process chemistry. In order to investigate this phenomenon, we have varied the amount of water dissolved in the organic phase by using several different organic diluents. The results of 137Cs and 89Sr batch distribution studies for the different organic diluents will be presented. These data and data from other spectroscopic techniques will be used to elucidate the details of the extraction mechanism