SANEX

The many laboratories involved in this work allowed a large experimental program to be set up to test the behavior of these soft donor extractants in countercurrent separations. The trivalent actinide-lanthanide separation process was named SANEX and four chemical systems have been explored (Fig. 12.20) ... 

SANEX 1 AqiMWUs feed AGidity 0.01 itio) dm - HNOj... 

Fig. 12.20 Extractants, diluents, and aqueous feeds for the trivalent 5f-4f ion group separations used in the SANEX processes.

SANEX 1 was based on the preferential extraetion of trivalent aetinides over lanthanides using as solvent 0.02 mol dm trA-pyridine (Tpy) + 1 mol dm a-bromoeaprie aeid in tert-butylbenzene. Flow sheet ealcu-lations showed that this proeess is operable but is very sensitive to the flow ratio (organie/aqueous) and the aqueous aeidity, whieh must be maintained around 0.01 mol dm... 

SANEX 3 used the 2,6-Z) -(5,6-dialkyl-1,2,4-triazine-3-yl)pyridine family of extraetants eontaining the propyl group, whieh are able to selectively extract trivalent actinides from Imoldm EINO3 [53,78]. The extractant was 0.04mol dm in a mixture of 70%/30% TPH/octanol. A flow sheet based on this solvent has been tried and is shown schematically in Fig. 12.21 the results are given in Table 12.13. The feed was an... 

Fig. 12.21 Flow sheet for the hot test of SANEX 3 process using n-Pr-BTP.

Table 12.13 Decontamination Factors, DF, for the Extraction (Mass in the Feed/Mass in the Actinide Back-Extraction) in the SANEX 3 Hot Test Depicted in Fig. 12.21... 

After the success of Kolarik (FZK) (326, 327), many BTPs were synthesized and tested as a candidate ligand for SANEX process in the frame of the NEWPART project (487). Among them 2,6-bis-(5,6-di- -propyl-l,2,4-triazin-3-yl)pyridine (nPr-BTP), without synergist, exhibited the best performance, for which SF[Am(III)/ Eu(III)] is >100 the feed acidity can be as high as 1M HN03, and with use of 0.04 M... 

FIGURE 1.8 Conceptual flowsheet of GANEX with a single cycle DIAMEX-SANEX process. 

Geist, A., Modolo, G., Weigl, M. 2003. SANEX-IV process development studies Di(chlorophenyl)dithiophosphinic acid as selective extractant for actinides(III). Proc Int Workshop on P T and ADS Development. SCK-CEN, Mol, Belgium, October 6-8. 

Hill, C., Guillaneux, D., Berthon, L., Madic, C. 2002. SANEX-BTP process development studies. J. Nucl. Sci. Technol. (Suppl 3) 309-312. 

Heres, X., Ameil, E., Martiniz, I., Baron, P, Hill, C. 2007. Extractant separation in DIAMEX-SANEX process. GLOBAL 2007, Boise, ID, September 9-13. 

Bidentate oxygen-donor extractants include the neutral diamide compounds, such as the malonamides used in the French DIAMEX and DIAMEX-SANEX processes, RR N(C=0)-CHR"-(C=0)NRR the bisphosphine oxides, RR (P=0)- CIIR"-(P=0) RR the carbamoyl-(methyl)-phosphinates, R0R 0(P=0)-(CI I On o 0rr(C=0)NRR or the more efficient carbamoyl-methyl-phosphine oxides, RR (P=0)-CHR"-(C=0)... 

There are various types of organic proton exchangers (34, 35, 38). Diesters of phosphoric acid, (RO)2P = 0(0H), phosphonic acids, R(RO)P = 0(0H), and phos-phinic acids, R2P = 0(0H), where R represents linear or branched alkyl or phenyl substituents, are the most common cation exchangers developed in liquid-liquid extraction for the extraction of trivalent 4/and 5/elements. They were initially developed for the American TALSPEAK and the Japanese DIDPA processes and have recently been introduced in the French DIAMEX-SANEX process. As for previously described NOPCs, these organophosphorus acids present oxygen-donor atoms (hard bases) in their structures and therefore will easily coordinate trivalent lanthanide and actinide cations, but they will not allow complete discrimination of the two families of elements. However, contrary to previously described neutral organophosphorus... 

The DIAMEX-SANEX/HDEHP process is probably the only single-step process that enables a complete selective An(III)/Ln(III) partitioning from non-pretreated PUREX raffinates (245). It combines two organic molecules possessing opposite but complementary extracting mechanisms ... 

As in the SETFICS and TALSPEAK processes, the DIAMEX-SANEX/HDEHP process involves selectively back-extracting the trivalent actinides by a hydrophilic polyamino-carboxylate complexing agent, HEDTA, in a citric acid buffered solution (pH 3). However, the combination of HDEHP and DMDOHEMA at high acidity promotes the coextraction of some block transition metals, such as Pd(II), Fe(III), Zr(IV), and Mo(VI), which must be dealt with by specific stripping steps (as described on Figure 3.26) that increase the total volume of the output streams ... 

FIGURE 3.26 DIAMEX-SANEX/HDEHP process flowsheet tested at the CEA Marcoule on a genuine PUREX raffinate. (Courtesy of Madic, C., Lecomte, M., Baron, P., Boullis, B., Compte-Rendu de Physique, 3, 797-811, 2002.)... 

It should be noted, however, that a simplified version of the DIAMEX-SANEX/ HDEHP process was also successfully implemented on a genuine highly active DIAMEX product (An(III) + Ln(III) fraction) in 2005, as the second step of an An(III)/Ln(III) partitioning scheme, in the scope of the technical feasibility validation of minor-actinide separation proposed by the CEA to address the issues of the 1991 French radioactive waste management act (154). 

Historically, pairs of processes have been developed throughout the world to achieve An(III)/Ln(III) partitioning TRUEX + TALSPEAK in the United States, TRPO + CYANEX in China, DIDPA + DIDPA in Japan, and DIAMEX + BTP or DIAMEX + ALINA in Europe, but cross combinations of processes are possible. The one-cycle processes (e.g., SETFICS and DIAMEX-SANEX/HDEHP) appear more attractive and more compact than the two-cycle processes, as they do not use two different solvent loops to carry out the separation of An(III) from Ln(III), but they sometimes generate much larger aqueous streams than the feed input. 

Baron, P., Heres, X., Lecomte, M., Masson, M. 2001. Separation of the minor actinides The DIAMEX-SANEX concept. Global 2001 Back-end of the Fuel Cycle From Research to Solutions, September, Paris, France. 

Magnusson, D., Christiansen, B., Glatz, J.P., Malmbeck, R., Modolo, G., Serrano Purroy, D., Sorel, C. 2008. Demonstration of minor actinide separation from a genuine PUREX raffinate by TODGA/TBP and SANEX reprocessing. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

C. 2008. Towards an optimized flow-sheet for a SANEX demonstration process using centrifugal contactors. ATALANTE 2008 Nuclear Fuel Cycles for a Sustainable Future, May, Montpellier, France. 

Bisel, I., Cam s, B Faucon, M Rudloff, D Saucerote, B. 2007. DIAMEX-SANEX solvent behaviour under continuous degradation and regeneration operations. Global 2007 Advanced Nuclear Fuel Cycles and Systems, September, Boise, ID. 

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