Behavior of long-lived fission and activation products in the near-field of a repository for nuclear waste and possibilities of their retention (VESPA II)
Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) GmbH (Braunschweig, Germany)
Institut für Energie- und Klimaforschung Nukleare Entsorgung und Reaktorsicherheit (IEK-6, Jülich, Germany)
Long-term safety assessments for final disposals of high-level radioactive waste have to consider the release of radionuclides from the waste and their potential retention by the multi-barrier system. To date, it has been assumed in long-term safety analysis that there is only retention for cationic but not for anionic species within the near field of final disposals.
In this context, the joint research project VESPA II, has the primary objective to investigate the retention of 79Se, 129I and 99Tc. In aquatic solutions, these elements mainly occur in anionic form and do not form poorly soluble phases. The goals of VESPA II are:
- filling the gaps on the reported thermodynamic data related to fission products and
- analyzing their retention by minerals phases likely found in the nearfield repository, such as corrosion products.
HZDR is involved in the following work packages
- studying the surface speciation and incorporation of Tc(VII) and Tc(IV) on iron corrosion phases, environmental ubiquitous minerals and on LDH phases under reducing conditions and
- investigating the Tc chemistry and thermodynamics, especially for low oxidation states.