Preparation of hexavalent americium in nitric acid solution

Fundamental investigations on preparation of Am(VI) in nitric acid solutions of various concentrations were carried out in order to develop a partitioning method for americium from high level liquid waste generated from the reprocessing of spent fuel. A mixture of ammonium peroxodisulfate and silver nitrate was used as oxidizing reagent. The yields of Am(VI) were determined as a function of the concentrations of nitric acid (0.01-2 M) and oxidizing reagent (0.1-2 M) and temperature (55-85degC). The yield of Am(VI) decreased with increasing concentration of nitric acid. In 1 M nitric acid solution, increasing the concentration of ammonium peroxodisulfate resulted in increased of Am(VI) yield. When 1.5 M ammonium peroxodisulfate and 0.01 M silver nitrate were used, 90% of the americium in 1 M nitric acid solution was oxidized to the hexavalent state at 85degC. (author)