Evaluation of Actinide(IV)-Silica colloids mobility under repository conditions - the NuWaMa Project


Evaluation of Actinide(IV)-Silica colloids mobility under repository conditions - the NuWaMa Project

Hildebrand, H.; Weiss, S.; Zaenker, H.; Kulenkampff, J.; Lippmann-Pipke, J.; Videnska, K.; Červinka, R.

Colloidal transport in the near-field and far-field of repositories is considered as one potential pathway for migration of (radio-)toxic components in case of groundwater intrusion. Recently, the in-situ formation of actinide(IV)-silica colloids (dp < 20 nm) was discovered under typical conditions for nuclear waste repositories in granitic formations (Dreissig et al. (2011), Hennig et al. (2013), Husar et al. (2015). These colloids show long-term stability over years and could therefore play a significant role in radionuclide migration since silica is an ubiquitous compound. So far, there is only little knowledge about the reactive transport of actinide(IV)-silica colloids under repository conditions. Within the NuWaMa project (intended start in January 2016), a new close collaboration between the Helmholtz-Zentrum Dresden - Rossendorf (HZDR) and the ÚJV Řež will be established and joint research focused on this problem will be intensified. First transport experiments using packed columns with crushed granite and distilled water amended with Th(IV)-silica colloids gave hints of mobility of the colloids under certain conditions. These experiments are conducted using conventional analytics such as ICP/MS and light scattering techniques for detection of the colloids in the column effluent. The aim of the project is also to evaluate this transport in more detail, including also by positron emission tomography (PET) with its unrivaled sensitivity and robustness for non-destructive quantitative spatio-temporal measurements. HZDR empowered “GeoPET” for its applicability in opaque/geological media (e.g. Kulenkampff et al., (2008), Kulenkampff et al.,(2015) , see Fig. 1). Zirconium radionuclides (positron-emitter and analogues for tetravalent actinides)shall be used for visualization of colloidal transport on column scale and, if applicable, also in a fractured rock sample.
The aim of the study, applied techniques and first results are intended to be shown as a poster presentation.

  • Poster
    BELBaR-Conference 2016 "Clay Colloids in Aqueous Systems", 03.-04.02.2016, Berlin, Deutschland

Permalink: https://www.hzdr.de/publications/Publ-23007
Publ.-Id: 23007