Neptunium concentration profiles in the Purex process

Numerical simulations of neptunium concentration profiles in the co-decontamination step of the Purex process is carried out in order to understand neptunium extraction behavior and to propose a flow sheet for neptunium recovery from the reprocessing process. A simulation result for a flow sheet containing Pu(VI) in the feed solution shows that Pu(VI) plays a role of scavenger of nitrous acid. The rate constant of neptunium reduction with n-butyraldehyde is evaluated by using the process data. The determined rate constant is available for the numerical simulation of neptunium concentration profiles in the reprocessing process.