JRP 05-12

Partners

FZK

CNRS

Contact

Dr. R. Klenze
Forschungszentrum Karlsruhe-INE P.O. Box 3640 - 76021 Karlsruhe Germany
Phone + 49 (0) 7247 82 46 02
E-mail e-mail

Study of the substitution mechanism of Actinides incorporated in secondary mineral phases by Optical Spectroscopy

Status

 
Ongoing - Planned from September 2006 till March 2008

Goals

The aim of this joint research project is to use high-resolution spectroscopy for the elucidation of the incorporation mechanisms of actinide ions entering secondary phases by co-precipitation and re-crystallisation from aqueous solution. Such processes have been recognized as very common sorption mechanisms under natural conditions.

In particular, the scientific objectives of this project are:

  • to examine the mechanism of incorporation of actinides into secondary mineral phases by co-precipitation and re-crystallisation in aqueous solution;
  • to evaluate the potential for utilizing high-resolution optical spectroscopy to gain fundamental insight into the incorporation mechanisms of nfN ions incorporated into selected mineral phases for various f-elements and occupied sites;
  • to perform the crystal field analysis of energy levels of nfN ions in various sites employing a semi-empirical Hamiltonian and superposition model. These results and further quantum mechanical calculations will provide information on the coordination of the incorporated felement and its distortions due to charge compensation;
  • to quantify the identified binding sites as a function of chemical conditions, which will finally provide thermodynamic and kinetic data based on a molecular process understanding.

Expected results

The results of this joint research project will help to develop appropriate thermodynamic/kinetic models to describe solid solution formation. On a medium time scale, such models are important for a sound quantification of radionuclide retention/retardation by secondary phase formation in performance assessment models.

Reports