Plutonium Redox Behavior in Aqueous Solutions and on Nanocrystalline Iron Phases

The redox behavior of Pu in aqueous solution is of particular interest for the disposal of nuclear waste in deep geological formations. Iron minerals are widespread in the environment and can be formed inside a repository by corrosion of steel canisters or construction materials. Their interaction with actinides and impact on redox chemistry needs to be understood for reliable performance assessment calculations.
The sorption and redox behavior of aqueous Pu(III) and Pu(V) in presence of synthetic nanocrystalline iron mineral suspensions and in homogeneous redox buffer solutions is investigated using a combination of classical wet chemistry methods and advanced spectroscopy (XANES, EXAFS). The impact of the redox conditions (pH + EH) in solution / suspension on the oxidation state distribution of Pu is studied by comparing the results to thermodynamic model calculations.