Spent fuel test on extraction in advanced reprocessing process

Extraction tests of the 44,000MWd/t spent fuel dissolver solution using bench scale reprocessing experimental equipment at BECKY (Back-end Fuel Cycle Elements Research Facility) were carried out using three extractors. The equipment composed diluent washing, Np oxidation, co-extraction, FP scrubbing, Np separation, Tc separation, U/Pu partitioning and U recovery steps. Vanadium (V) oxide with nitric acid was used as an Np oxidizing agent. Butyraldehyde (decomposable and salt-free organic reducing agent) and 6M nitric acid were fed into the extractor in order to separate Np and Tc. As a result 64.8% of the Np and 98.9% of the Tc were extracted in the co-extraction step. 75.0% of the extracted Np was separated from the U and Pu stream in the Np separation step. On the other hand, 81.8% of the Tc was separated by 6M nitric acid in the Tc separation step. In the U/Pu partitioning step, Pu was reduced from Pu (IV) to Pu (III) and stripped into aqueous phase by uranous nitrate and hydrazine in 1M nitric acid. Most of the Np remained in the U loaded solvent (organic phase). To the contrary, Tc migrated to the Pu solution (aqueous phase). It was found that butyraldehyde and 6M nitric acid were effective in separating Np and Tc from the U and Pu stream. These technologies are expected to be applied to simplified reprocessing process. (author)