Di-1-methyl heptyl methylphosphonate (DMHMP): A promising extractant in Th-based fuel reprocessing

Abstract

In this paper, the physical properties of tri-iso-amyl phosphate (TiAP), tri-sec-butyl phosphate (TsBP) and di-1-methyl heptyl methyl phosphonate (DMHMP) were studied and compared with tri-n-butyl-phosphate (TBP). Furthermore, the extraction behaviors of U(VI), Th(IV), nitric acid and fission products, and the extraction capacity of Th(IV) in different extractants were also investigated. The results indicated that the physical and extraction properties of DMHMP were better than that of other extractants and it is more appropriate to be used in thorium-based fuel reprocessing. A thorium-uranium co-decontamination process using DMHMP as extractant was proposed, optimized and verified by multistage countercurrent extraction using batch simulation and centrifugal extractors. By comparison with conventional Thorex process using TBP as extractant, it is found that DMHMP is more promising in thorium-based fuel reprocessing.