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