[en] The Universal Extraction (UNEX) process has been developed for simultaneous extraction of cesium, strontium, and actinides from acidic solutions. This process utilizes an extractant consisting of 0.08 M chlorinated cobalt dicarbollide (HCCD), 0.007-0.02 M polyethylene glycol (PEG-400), and 0.02 M diphenyl- N,N-di-n-butyl-carbamoyl-methyl-phosphine oxide (Ph₂CMPO) in the diluent tri-fluoro-methyl-phenyl sulfone (CF₃C₆H₅SO₂, designated FS-13) and provides simultaneous extraction of Cs, Sr, actinides, and lanthanides from HNO₃ solutions. The UNEX process is of limited utility for processing acidic solutions containing large quantities of lanthanides and/or actinides, such as dissolved spent nuclear fuel solutions. These constraints are primarily attributed to the limited concentrations of CMPO (a maximum of ∼ 0.02 M) in the organic phase and limited solubility of the CMPO-metal complexes. As a result, alternative actinide and lanthanide extractants are being investigated for use with HCCD as an improvement for waste processing and for applications where higher concentrations of the metals are present. Our preliminary results indicate that diamide derivatives of di-picolinic acid may function as efficient actinide and lanthanide extractants. The results to be presented indicate that, of the numerous diamides studied to date, the tetra-butyl-diamide of di-picolinic acid, TBDPA, shows the most promise as an alternative actinide/lanthanide extractant in the UNEX process. (authors)