Demonstration of T2EHDGA Based Process for Actinide Partitioning Part II: Counter-Current Extraction Studies

Counter-current mixer-settler studies for actinide partitioning were carried using N,N,N′,N′-tetra-2-ethylhexyl diglycolamide (T2EHDGA) as the extractant. The feed solution was Simulated High Level Waste of Pressurized Heavy Water Reactor (PHWR-SHLW) origin spiked with 241Am, 244Cm, 152Eu, 137Cs, 85,89Sr, 59Fe, 106Ru, 109Pd, 95Zr, and 99Mo tracers. The organic stream was 0.1 M T2EHDGA + 5% isodecanol in n-dodecane. Extraction, scrubbing, and stripping experiments were performed by maintaining an organic to aqueous phase ratio of 1. More than 99.9% of the trivalent actinides and lanthanides were extracted in four stages, and the decontamination factors (D.F.) values were >103 obtained for most fission products. The co-extraction of Zr and Pd was prevented by the addition of oxalic acid and N-(2-hydroxyethyl)-ethylenediamine-triacetic acid (HEDTA) into the feed solution. However, ∼20% Ru and 10% Mo was extracted into the organic phase, which was successfully scrubbed using a mixture of 0.2 M oxalic acid and 0.1 M HEDTA in 5 M HNO3. Finally, the extracted actinides and lanthanides were quantitatively stripped with 0.2 M HNO3. Raffinate of the extraction cycle was found to be free from any alpha activity.