TRansUranic Extraction process

Different radionuclides have different chemistry, so it seems reasonable to include each nuclide in a specific matrix that is most stable for the desired nuclide. It is possible to find stable matrices for incorporation of numerous nuclides with similar chemical properties. The target elements for such incorporation are the long-lived radionuclides (transuranic elements), 90Sr, 137Cs, and Tc. Many extraction processes have been proposed for radionuclide removal from radioactive wastes. Typically, the goal of the processes is to extract one radionuclide or multiple radionuclides... 

Vandegrift, G.F., Leonard, R.A., Steindler, M.A., Hortwitz, E.P., Basile, L.J., Diamond, H., Kalina, D.G., Kaplan, L. 1984. Transuranic decontamination of nitric acid solutions by the TRUEX solvent extraction process-preliminary development studies. Report ANL-84-45, Argonne National Laboratory, Argonne, IL. 

Vandegrift, G. F., R. A. Leonard, M. J. Steindler, et al. 1984. Transuranic Decontamination of Nitric Acid Solutions by the TRUEX Solvent Extraction Process-Preliminary Development Studies. Argonne National Laboratory Report ANL-84-45, Argonne, IL. 

UREX [URanium Extraction] A solvent extraction process for extracting uranium and technetium from used nuclear fuel, while rejecting all the transuranic elements. Based on the Purex process, which uses tributyl phosphate in a hydrocarbon mixture, but incorporating acetohydroxamic acid, which complexes the Pu and Np and thereby prevents them from being extracted. Developed by the Westinghouse Savannah River Company in 2003. Associated processes are NPEX, TRUEX, and Cyanex 301. 

The second step is to dissolve the metal oxide fuel using strong nitric acid. The object is to bring all the fission products, uranium, and transuranics, into solution to feed the extraction process. Some of the fission products exceed solubility limits and the fine solids formed must be removed before extraction. Provisions to recover nitrogen oxides and collect gaseous fission products released during this step must be in place. The stainless steel and zircaloy fuel jackets from the fuel assemblies do not dissolve and are separated from the solution, washed, checked for radioactivity, and packaged for disposal as low-level radioactive waste. 

Nuclear Waste Reprocessing. Liquid waste remaining from processing of spent reactor fuel for military plutonium production is typically acidic and contains substantial transuranic residues. The cleanup of such waste in 1996 is a higher priority than military plutonium processing. Cleanup requires removal of long-Hved actinides from nitric or hydrochloric acid solutions. The transuranium extraction (Tmex) process has been developed for... 

Tramex [Transuranic metal (or amine) extraction] A process for separating transuranic elements from fission products by solvent extraction from chloride solutions into a tertiary amine solution. Developed at Oak Ridge National Laboratory, TN, for processing irradiated plutonium. 

Truex [Transuranium extraction] A process for removing transuranic elements during the processing of nuclear fuel by solvent extraction. Developed by E. P. Howitz at the Argonne National Laboratory, Chicago, IL. See also SREX. 

Horwitz, E.P., Kalina, D.G., Diamond, H Vandegrift, G.F., Schulz, W.W. The TRUEX process - a process for the extraction of the transuranic elements from nitric acid wastes utilizing modified Purex solvent. Solvent Extr. Ion Exch. (1985), 3 (1 2), 75-109. 

DIAMEX [DIAMide Extraction] An alternative to the TRUEX process for removing transuranic elements from nuclear waste. The extraction agent is malondiamide, which can more easily be burned off than organic phosphates. Developed by the CEA in France. 

TRUEX [TRansUranium Extraction] A process for removing transuranic elements and lanthanide fission products during the processing of nuclear fuel by solvent extraction. The solvent is a complex phosphine oxide mixed with tributyl phosphate and diluted with n-dodecane. By removing the transuranic elements, the alpha activity of the waste is greatly reduced and the residue is easier to dispose of. Developed by E.P. Horwitz at the Argonne National Laboratory, Chicago, IL. See also SREX, UREX+. 

Pu, Am, Cm 5 X 10 M) in the presence of several fission product contaminants in a synthetic waste of PUREX origin. A solution of 0.5 M formic acid and 0.1 M sulfuric acid was utilized as the receiving phase (22,25). Some of the experimental parameters which characterized the process are listed in Table 3. With a series of 20 modules, 99.9 % of Am was recovered from 2 X 10" L of feed solution in 24 hours. In subsequent experiments, a second SLM containing 1 M Primene JM-T in decalin was connected in series to the first SLM to overcome the reduction in strippant effectiveness caused by nitric acid transport into the strippant (29,30), The second helper SLM extracted only nitric acid from the first stripping solution which was 1 M formic acid (plus 0.05 M hydroxylammonium formate in the case of Pu(IV) transport). The stripping solution for the second SLM was 4 M sodium hydroxide. Results of these laboratory-scale studies demonstrate that actinides can be efficiently removed from such effluents to the point that the resulting solution can be considered a non-transuranic waste (<100 nCi/g of disposed form). 

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