Np(IV) distribution between 30% tributylphosphate in odourless kerosene and nitric acid

A methodology has been developed to study the distribution of Np(IV) betwee n 30% tributyl phosphate in odourless kerosene and aqueous nitric acid. Dis tribution coefficients were radiometrically determined across a range of HN O3 concentrations. Spectrophotometry was used to follow the extraction and to ensure that the conversion of Np(IV) to other oxidation states, which wo uld introduce inaccuracies into the measurement of distribution coefficient s, did not occur. The distribution data calculated in this study have been shown to be consistent with the literature and to reliably extend our under standing of the solvent extraction behaviour of Np(IV), particularly at low er acidities. The data have been used to update mathematical algorithms, de scribing the extraction of Np(IV), which are used in the simulation of PURE X process flowsheets.