UNEX process

Romanovskiy, V.N., Smirnov, I.V., Babain, V.A. et al. 2001. The universal solvent extraction (UNEX) process. I. Development of the UNEX process solvent for the separation of cesium, strontium, and the actinides from acidic radioactive waste. Solvent Extr. Ion Exch. 19 (1) 1-21. 

The UNEX Process A Universal Solvent Intensive collaboration between the INL and the Khlopin Radium Institute of Saint Petersburg (KRI, Russia) since 1994 has resulted in the development of the UNEX process for the treatment of radioactive waste stored at the INL (116-125). The UNEX process is based on the following tertiary solvent ... 

FIGURE 3.3 Cobalt dicarbollide andPh2-CMPO used in the UNEX process. 

Testing and demonstration of concept feasibility of the UNEX process has been completed on batch contact studies using simulated and genuine sodium-bearing acidic waste stored in underground stainless steel tanks at the INL. DFs of 99.7% for Sr, > 95% for Cs, and 99.99% for actinides were achieved with a solvent composed of CCD, PEG, and Ph2-CMPO, dissolved in either a light or a heavy non-nitroaromatic diluent (respectively less or more dense than the aqueous feed). 

The feasibility of recovering hazardous radionuclides from acidic waste solutions by the UNEX process is demonstrated. However, the tests also confirm that the solvent composition should be adjusted to attain optimum results depending on the waste composition (123). Besides, traditional UNEX process has some drawbacks ... 

FIGURE 3.5 2,6-Pyridinedicarboxamide derivates investigated for the UNEX process. 

Peterman, D.R., Herbst, R.S., Law, J.D., Tillotson, R.D., Gam, T.G., Todd, T.A., Romanovskiy, V.N., Babain, V.A., Alyapyshev, M.Y., Smirnov, I.V. 2005. Diamide derivatives of dipicolinic acid as actinide and lanthanide extractants in a variation of the UNEX process. Global 2005 Nuclear Energy System for Future Generation and Global Sustainability, October, Tsukuba, Japan. 

Romanovskiy, V. N., I. V. Smirnov, V. A. Babain, et al. 2005. UNEX-Process, State of the Art and Outlook. Proceedings of GLOBAL 2005, Paper 353, October 9-13, Tsukuba, Japan. 

Collaborative research by the Idaho National Laboratory and the Khlopin Radium Institute (St. Petersburg, Russia) has developed and validated the concept of a Universal Extraction (UNEX) process, for the simultaneous separation of cesium, strontium, the actinides, and the lanthanides from acidic waste solutions. The UNEX process solvent consists of... 

In this chapter, we review the achievements in the area of extractions with boron extractants accomplished in the last five years. The literature on extraction with cobalt bis(dicarbollide) and synergist, the UNEX process, and new boron-selective extractants is ample, and other connected science, such as ion-selective electrodes with boron anions, boron anion room-temperature ionic liquids, modeling of the mechanism of the extraction, IR studies on extracts, the state of CD in water solutions, or a description of some of the new ideas on solvation, resolvation theory, and so on, could not be covered here. 

Russian and U.S. scientists have made several important improvements in the area of the UNEX process and a number of technological studies concerning the process in detail have been carried out (Herbst, 2002a,b). 

The CMPO derivatives have been designed as efficient extractants for the trivalent lanthanide/ actinide group separation in the TRUEX process studied in the United States and Russia, see, for example, the review by Paiva and Malik (2004). Danonstration tests on the use of synergic mixtures of CMPO (Af,A-di-isopropyl carbamoyl methyl alkyl phenyl phosphine oxide) and chloroderivative CCD" for lanthanide/actinide extraction have been carried out in the development of the UNEX process, see Section 19.2.2 of this review. 

Alekseenko, S., Babain, V. A., Bondin, V. et al. 2005. Testing of UNEX-process on Centrifugal Contactor Mocup of Mining and Chemical Combine. In Global 2005 Paper No. 347, Tsukuba, Japan, 9-13 October, 2005. 

Luther, T. A., Herbst, R. S., Peterman, D. R. et al. 2006. Some aspects of fundamental chemistry of the Universal Extraction (UNEX) process for the simultaneous separation of major radionuclides (cesium, strontium, actinides, and lanthanides) from radioactive wastes. J. Radioanal. Nucl. Chem. 267 603-613. 

---