Homogenous recycling of transuranium elements from irradiated fast reactor fuel by the EURO-GANEX solvent extraction process

Abstract

The EURO-GANEX process was developed for co-separating transuranium elements from irradiated nuclear fuels. A hot flow-sheet trial was performed in a counter-current centrifugal contactor setup, using a genuine high active feed solution. Irradiated mixed (carbide, nitride) U80Pu20 fast reactor fuel containing 20 % Pu was thermally treated to oxidise it to the oxide form which was then dissolved in HNO3. From this solution uranium was separated to >99.9 % in a primary solvent extraction cycle using 1.0 mol/L DEHiBA (N,N-di(2-ethylhexyl)isobutyramide in TPH (hydrogenated tetrapropene) as the organic phase. The raffinate solution from this process, containing 10 g/L Pu, was further processed in a second cycle of solvent extraction. In this EURO-GANEX flow-sheet, TRU and fission product lanthanides were firstly co-extracted into a solvent composed of 0.2 mol/L TODGA (N,N,N′,N′-tetra-n-octyl diglycolamide) and 0.5 mol/L DMDOHEMA (N,N′-dimethyl-N,N′-dioctyl-2-(2-hexyloxy-ethyl) malonamide) dissolved in Exxsol D80, separating them from most other fission and corrosion products. Subsequently, the TRU were selectively stripped from the collected loaded solvent using a solution containing 0.055 mol/L SO3-Ph-BTP (2,6-bis(5,6-di(3-sulphophenyl)-1,2,4-triazin-3-yl)pyridine tetrasodium salt) and 1 mol/L AHA (acetohydroxamic acid) in 0.5 mol/L HNO3; lanthanides were finally stripped using 0.01 mol/L HNO3. Approximately 99.9 % of the TRU and less than 0.1 % of the lanthanides were found in the product solution, which also contained the major fractions of Zr and Mo.

A microfluidic study of synergic liquid–liquid extraction of rare earth elements

“…Furthermore the viscosity of solutions containing typically 30% of DMDOHEMA in a solvent is acceptable for process design. 53,54 Moreover, modern predictive approaches exist: (i) to calculate the viscosities observed when solutions are loaded with uranium; 55,56 (ii) to derive the critical micellar concentration (cmc) of extractants in different solvents, not only alkanes and solvo-surfactants, but also ionic liquids (such as COSMO-RS). 57 Overall, our study allows determining the influence of (i) the molar fraction, X DMDOHEMA , of the solvating extractant (eqn (4)); (ii) the acidity and; (iii) the temperature, on the kinetics, efficiencies and selectivities of the extraction.…”

Solvent extraction of An(III) and Ln(III) using TODGA in aromatic diluents to suppress third phase formation

“…[11][12][13][14] C ec e ce e i g DGA e ac i g age (N,N,N ,N -tetra-n-octyl-3-oxapentanediamide (TODGA, Figure 1) or N,N,N ,N -tetra-(2-ethylhexyl)-3oxapentanediamide, TEHDGA) ha e cce f bee e f ed i ab a ca e e i e . [15][16][17][18][19][20][21] TODGA ha e e i e bee ed i ece E ea e ea ch g a e i a i e c ea f e c c e [22][23][24] de e ce e c -e ac i g ac i ide a d a ha ide f ed b e ec i e i i g f ac i ide . 7,17,19,[25][26][27][28][29][30] A i a i e i h DGA e ac i g age he di ed i a i ha ic di e i hei e e hi d ha e f a i he i c ac i h i c ai i g i ic acid a d e a i i e e a ed c ce a i .…”

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

“…The focus within EU research over the past decade with respect to separation processes has been the development of several Grouped ActiNide EXtraction (GANEX) processes for the co-extraction of all transuranic elements from spent nuclear fuel. [5][6][7][8][9][10][11] These processes all include a primary cycle for the bulk extraction of uranium, [12] followed by a second cycle for transuranic element extraction. [13] Three different second-cycle GANEX processes are currently being investigated: CEA-GANEX, [13] EURO-GANEX, [10] and Chalmers-GANEX (CHALMEX).…”

“…[5][6][7][8][9][10][11] These processes all include a primary cycle for the bulk extraction of uranium, [12] followed by a second cycle for transuranic element extraction. [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.…”