The Application of Acetohydroxamic Acid to the TBP Extraction of Uranium and Neptunium from a Simulated Solution

Irradiated spent nuclear fuel is usually reprocessed by a chemical process to recover the U and Pu from the radioactive fission products. However, a spent nuclear fuel usually contains minor actinides other than the useful U and Pu. A solvent extraction process is currently being developed to separate uranium, which will meet the criteria for a nuclear waste disposal as a class C low-level waste. In this case, Np and Pu are generally regarded as unwanted components and particularly the U products have restrictive specifications. Therefore, their effective control during a chemical process is important for an efficient production of a purified U product. Such a process must also minimize the waste volume by converting all the chemicals to gases during a subsequent processing. To meet this requirement, the current process was designed to use reagents in the scrub stream. Recently, new salt free reagents to separate Pu and Np from U, suitable for use in a single cycle flowsheet, have been developed. Acetohydroxamic acid (AHA) has received considerable interest as a reductant/complexant of choice for the process to reject Np along with Am, Cm, and fission products because it can reduce Np(VI) to Np(V) quickly and it can create a Np(IV) complex. These characteristics will allow U(VI) to be extracted free of transactinides. Since AHA is composed of only C, H, O and N atoms they can be readily decomposed to gases so that their incorporation in to industrial processes will not lead to increases in a waste volume. In this study, distribution ratios of Np(IV), Np(VI) and U between 30 vol% TBP/n-dodecane and 1M nitric acid were measured with varying concentrations of AHA