Counter-current extraction for actinides partitioning from PHWR-SHLW using N,N,N',N'-tetra-2-ethylhexyl diglycolamide (TEHDGA)

Active counter-current extraction for actinide partitioning was carried out with 0.1M TEHDGA + 5% isodecanol in n-dodecane using 12 stages mixers-settlers unit. The feed solution was Simulated High Level Waste (SHLW) obtained after reprocessing of Pressurized Heavy Water Reactor (PHWR) fuel spiked with Am, Cm, Eu, Cs, Sr, Pd, Zr, Fe, Ru and Mo tracers. Extraction, scrubbing and stripping experiments were performed by maintaining organic to aqueous phase ratio of 1. The results showed that all the lanthanide and actinides were selectively extracted in the organic phase in four stages. The extraction of Z and Pd was prevented by addition of oxalic acid and HEDTA in the feed solution, respectively. However, ∼ 20% Ru and 10% Mo was extracted which was successfully scrubbed with 0.2M oxalic acid + 0.1M HEDTA at 5M HNO3. Finally, the extracted actinides and lanthanides were quantitatively stripped with 0.2M HNO3. (author)