Enhancing decontamination of zirconium and ruthenium in the Thorex process using acetohydroxamic acid

The decontamination of some extractable fission products, such as Zr and Ru, is an important issue in the Thorex process. Acetohydroxamic acid (AHA) is an organic ligand composed of only C, H, N and O atoms. It can be used as complexing and reducing agent to inhibit the extraction of Zr and Ru. In this paper, the effect of AHA and preheating on the extraction of Th, U, Zr and Ru was studied. It is found the extraction of Zr and Ru would be inhibited in the presence of AHA and preheating, meanwhile there was no obvious effect on the extraction of Th and U. Afterwards, the countercurrent extraction using centrifugal extractors was performed to further test and verify the effect of AHA in a typical Thorex process. The results indicate that the decontamination of Zr and Ru could be enhanced evidently due to the effect of AHA, and the corresponding decontamination factor would be improved from 27.0 to 3.3 × 103 and 111.0 to 1.5 × 103, respectively. Thus, the use of AHA would be an efficient means for enhancing the decontamination of Zr and Ru in Thorex process.