Open Access Publication of the Month – Dr. Naila Ait-Mouheb (IFN-2) et al.

6 September 2024
To encourage us all to broaden our horizons, each month the Central Library selects one open access publication from the JuSER publications portal to be featured in the newsletter of Forschungszentrum Jülich.
In the open access publication of the month, Dr. Naila Ait-Mouheb (IFN-2) at al. write about the effects of the heterogeneity of clay rocks on the retention behaviour of 226Ra as a critical radionuclide to be considered in safety cases for direct disposal of spent nuclear fuels.
Germany is currently searching for a site for the disposal of heat-generating, high-level radioactive waste (HLW). The repository will be located in a geological formation of crystalline rock, salt rock, or clay rock. The site “Nördlich Lägern” has been selected as the most suitable site in Switzerland, where the Opalinus Clay (OPA) is present as a 100 m thick layer. Recently, the part of OPA formation in southern Germany has been considered as one of the German generic models for developing a safety demonstration methodology for a HLW repository in clay rock. In this context, the effects of natural heterogeneities of 226Ra migration in clay rocks were investigated using the lower OPA sandy facies from the Mont Terri underground research laboratory as an example.
The article demonstrates that a simplified bottom-up approach addressing cation exchange/surface complexation reactions significantly underestimated the experimental findings. Modelling solid-solution formation of Ra with (Ba,Sr)-SO4 indicated that significantly higher amounts of sulfate minerals in the OPA-SF would be required to make this retention mechanism effective. Furthermore, it emphasizes the necessity of further assessing the formation of Ra-bearing carbonate solid solutions as a potential retardation mechanism for 226Ra in carbonate-bearing clay rocks.
The open access publication entitled "Retention of 226Ra in the sandy Opalinus Clay facies from the Mont Terri rock laboratory, Switzerland" was published in the journal Applied Geochemistry.
JuSER publications portal – Retention of 226Ra in the sandy Opalinus Clay facies from the Mont Terri rock laboratory, Switzerland