On the Basic Extraction Properties of a Phenyl Trifluoromethyl Sulfone-Based GANEX System Containing CyMe₄-BTBP and TBP

Abstract

A Grouped ActiNide EXtraction (GANEX) process for the extraction of actinides from used nuclear fuel for transmutation purposes has been investigated. The studied solvent consists of phenyl trifluoromethyl sulfone (FS-13), CyMe 4-BTBP, and TBP, a combination that has previously shown promising results. The time to reach extraction equilibrium for the system has been found to be less than 20 min. A 2:1 complex has been found between CyMe 4-BTBP and americium (III) or curium(III), whereas plutonium(IV) and CyMe 4-BTBP create a 1:1 complex. The extraction of fission product is low in the system.

Batch Tests for Optimisation of Solvent Composition and Process Flexibility of the CHALMEX FS-13 Process

“…The distribution ratios then remain fairly constant at values of around 30. As the trivalent Am and Eu are extracted by CyMe 4 -BTBP and not by TBP, [15,17] this is believed to be due a better solubility of the Am/Eu complexes in the TBP/FS-13 mixture compared to pure FS-13. Ekberg et al, [43] found that both the stability and the solubility of such complexes increases with decreasing charge density of the solvent.…”

“…The distribution ratio Pu of 2.26 for 0% v/v TBP also confirms that plutonium is extracted by CyMe 4 -BTBP as reported earlier. [15] Due to the significant increase in both americium and plutonium extraction above 30% v/v TBP, while higher TBP concentrations do not yield further improvement, 30% v/v TBP was chosen as the optimal TBP volume ratio. Neptunium(V,VI) extraction did not show a clear trend as a function of the TBP/FS-13 volume fraction.…”

“…[13] . proposed by Ochin et al [15,50] Two slopes were also distinguished for the neptunium extraction: before and after the suspected reduction. The slopes (0.62 and 0.98, respectively), suggest the opposite, however: an oxidation of Np(V) to Np(VI).…”

“…[13] Three different second-cycle GANEX processes are currently being investigated: CEA-GANEX, [13] EURO-GANEX, [10] and Chalmers-GANEX (CHALMEX). [14][15][16][17][18] The former two are based on the principle of extracting actinides and lanthanides together, for a subsequent selective stripping of the actinides. The latter, the CHALMEX process, differs by selectively co-extracting the actinides from spent nuclear fuel, thus potentially reducing the number of process steps.…”

“…The contacting time was 60 minutes, as this has previously been verified as sufficient time to reach equilibrium in the studied system. 15 Trace amounts of 241 Am(III), 152 Eu(III), 237 Np(V) or 239 Np(V, VI), and 238 Pu(IV) or 238,239,240,241 Pu(IV) were added to the respective aqueous phases prior to contacting. The extraction of americium and europium was investigated in one system, while neptunium and plutonium were investigated in individual systems.…”