Distribution of micro-amounts of europium in the two-phase water–HCl–nitrobenzene–N,N’-dimethyl-N,N’-diphenyl-2,6-di-picolinamide–hydrogen dicarbollylcobaltate extraction system

Extraction of micro-amounts of europium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of N,N’-dimethyl-N,N’-diphenyl-2,6-dipicolinamide (MePhDPA, L) was investigated. The equilibrium data were explained assuming that the species HL+, HL+2, HL3+2 and HL3+3 are extracted into the organic phase. The values of the extraction and stability constants of the species in nitrobenzene saturated with water were determined

Demonstration of a Universal Solvent Extraction Process for the Separation of Cesium and Strontium from Actual Acidic Tank Waste at the INEEL

A universal solvent extraction process is being evaluated for the simultaneous separation of Cs, Sr, and the actinides from acidic high-activity tank waste at the Idaho National Engineering and Environmental Laboratory (INEEL) with the goal of minimizing the high-activity waste volume to be disposed in a deep geological repository. The universal solvent extraction process is being developed as a collaborative effort between the INEEL and the Khlopin Radium Institute in St. Petersburg, Russia. The process was recently demonstrated at the INEEL using actual radioactive, acidic tank waste in 24 stages of 2-cm-diameter centrifugal contactors located in a shielded cell facility. With the testing, removal efficiencies of 99.95%, 99.985%, and 95.2% were obtained for Cs-137, Sr-90, and total alpha, respectively. This is sufficient to reduce the activities of Cs-137 and Sr-90 to below NRC Class A LLW requirements. The total alpha removal efficiency was not sufficient to reduce the activity of the tank waste to below NRC Class A non-TRU requirements. The lower than expected removal efficiency for the actinides is due to loading of the Ph2Bu2CMPO in the universal solvent with actinides and metals (Zr, Fe, and Mo). Also, the carryover of aqueous solution (flooding) with the solvent exiting the actinide strip section and entering the wash section resulted in the recycle of the actinides back to the extraction section. This recycle of the actinides contributed to the low removal efficiency. Significant amounts of the Zr (>97.7%), Ba (>87%), Pb (>98.5%), Fe (>6.9%), Mo (19%), and K (17%) were also removed from the feed with the universal solvent extraction flowsheet

DIAMIDE DERIVATIVES OF DIPICOLINIC ACID AS ACTINIDE AND LANTHANIDE EXTRACTANTS IN A VARIATION OF THE UNEX PROCESS

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-butylcarbamoylmethylphosphine oxide (Ph2CMPO) in the diluent trifluoromethylphenyl 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 dipicolinic acid may function as efficient actinide and lanthanide extractants. The results to be presented indicate that, of the numerous diamides studied to date, the tetrabutyldiamide of dipicolinic acid, TBDPA, shows the most promise as an alternative actinide/lanthanide extractant in the UNEX process

Fluorinated carbonates as new diluents for extraction and separation of f-block elements

The fluorinated carbonate BK-1 solvent was studied as a diluent in extraction systems with different extracting agents – CMPO, THDGA, CyMe4-BTBP, and CyMe4-BTPhen, which are the most promising molecules for separation of minor actinides and lanthanides. Dependence of the extraction properties of the system on the concentrations of HNO3 or extracting compound, kinetics of trivalent metal extraction and extraction of the ions by neat diluent (without the addition of extracting agent) were investigated. Based on the obtained results, BK-1 is a promising candidate diluent for f-block metal separation

Novel Solvent for the Simultaneous recovery of Radioactive Nuclides from Liquid Radioactive Wastes

The present invention relates to solvents, and methods, for selectively extracting and recovering radionuclides, especially cesium and strontium, rare earths and actinides from liquid radioactive wastes. More specifically, the invention relates to extracting agent solvent compositions comprising complex organoboron compounds, substituted polyethylene glycols, and neutral organophosphorus compounds in a diluent. The preferred solvent comprises a chlorinated cobalt dicarbollide, diphenyl-dibutylmethylenecarbamoylphosphine oxide, PEG-400, and a diluent of phenylpolyfluoroalkyl sulfone. The invention also provides a method of using the invention extracting agents to recover cesium, strontium, rare earths and actinides from liquid radioactive waste

Fundamental UNEX Chemistry

This presentation was given at the DOE Office of Science-Environmental Management Science Program (EMSP) High-Level Waste Workshop held on January 19-20, 2005 at the Savannah River Site

Short communication

Distribution of micro-amounts of europium in the two-phase water–HCl–nitrobenzene–N,N’-dimethyl-N,N’-diphenyl-2,6-dipicolinamide–hydrogen dicarbollylcobaltate extraction syste

Demonstration of a Universal Solvent Extraction Process for the Separation of Cesium and Strontium from Actual Acidic Tank Waste at the INEEL

A universal solvent extraction process is being evaluated for the simultaneous separation of Cs, Sr, and the actinides from acidic high-activity tank waste at the Idaho National Engineering and Environmental Laboratory (INEEL) with the goal of minimizing the high-activity waste volume to be disposed in a deep geological repository. The universal solvent extraction process is being developed as a collaborative effort between the INEEL and the Khlopin Radium Institute in St. Petersburg, Russia. The process was recently demonstrated at the INEEL using actual radioactive, acidic tank waste in 24 stages of 2-cm-diameter centrifugal contactors located in a shielded cell facility. With the testing, removal efficiencies of 99.95%, 99.985%, and 95.2% were obtained for Cs-137, Sr-90, and total alpha, respectively. This is sufficient to reduce the activities of Cs-137 and Sr-90 to below NRC Class A LLW requirements. The total alpha removal efficiency was not sufficient to reduce the activity of the tank waste to below NRC Class A non-TRU requirements. The lower than expected removal efficiency for the actinides is due to loading of the Ph2Bu2CMPO in the universal solvent with actinides and metals (Zr, Fe, and Mo). Also, the carryover of aqueous solution (flooding) with the solvent exiting the actinide strip section and entering the wash section resulted in the recycle of the actinides back to the extraction section. This recycle of the actinides contributed to the low removal efficiency. Significant amounts of the Zr (>97.7%), Ba (>87%), Pb (>98.5%), Fe (>6.9%), Mo (19%), and K (17%) were also removed from the feed with the universal solvent extraction flowsheet

Treatment of acidic INEEL waste using a countercurrent cobalt dicarbollide-based universal solvent extraction process

A tertiary solvent containing chlorinated cobalt dicarbollide, diphenylcarbamoylmethylphosphine oxide and polyethylene glycol in different diluents was evaluated for the separation of cesium, strontium, actinides and rare earth elements from acidic liquid radioactive waste in countercurrent solvent extraction processes. This universal solvent extraction process has been demonstrated in 24-stage centrifugal contactor pilot plants, using simulated acidic tank waste, at the Khlopin Radium Institute (KRI), St. Petersburg, Russia, and at the Idaho National Engineering and Environmental Laboratory (INEEL). Demonstration of the universal extraction process with actual tank waste is scheduled at the INEEL in 1998