Research

Current research projects of the AG WASTe

 

 

Further research  (only in German language)

 

Joint project GRaZ II: "Geochemical radionuclide retention on cement aging phases".

Funded by BMWi (2021-2023)

Overview
The topic of the research project is the retention of radionuclides (actinides) in the near-field of a repository for heat-generating radioactive waste in claystone formations of northern Germany according to the NORD siting model. For the safety demonstration of such a repository, there are knowledge gaps on the influence of dissolved iron, which is released during the corrosion of the emplacement containers, and of organic and silicate ligands resulting from the concrete or cement corrosion of the engineered barrier. A special feature of the NORD site model is the medium to high ionic strength of the formation waters of the clay rock. Therefore, the influence of iron and the organic and silicate ligands on radionuclide retention at cement corrosion phases and the bentonite buffer under hyperalkaline conditions at medium to high ionic strengths is to be quantified. For this purpose, the processes sorption, diffusion, complexation, redox transformation and solubility are studied with experimental and quantum chemical methods, elucidated on the molecular level and described with thermodynamic models. On the basis of the results achieved in this project and the previous joint project "Geochemical radionuclide retention at cement ageing phases (GRaZ I)", it will be critically evaluated to what extent existing findings for systems of low ionic strength are applicable to the conditions of medium to high ionic strength according to the NORD site model.

Subproject D (Saarland University):
"Retention, fixation and remobilisation of repository-relevant elements and element mixtures at cement ageing stages".
The planned research work at the UdS relates in particular to the interactions of radionuclides and their homologues with cement or concrete and their alteration products within the geotechnical barrier of a potential repository under the influence of high-saline and hyperalkaline conditions. The main focus is to investigate the behaviour of repository-relevant elements or element mixtures under different geochemical conditions (formation waters, cement additives and competing ions). The selected elements are U(VI) as nuclear fuel or Mo(VI) as a possible homologous element, Eu(III) as a representative for the trivalent actinides, and Cs(I), Sr(II), Pd(II), Sm(III), Zr(IV) and Ru(IV) as possible degradation or fission products, as structural parts (e.g. cladding tubes or ingot moulds) and as non-radioactive homologous representatives. In addition to single-element experiments, the investigations are mainly carried out with element mixtures ("WASTe cocktail") using multi-element ICP-MS in the concentration range from 10-9 to 10-6 mol/L.

 

 

 

 

 


PD Dr. Ralf Kautenburger

+49-(0)681 302 2171
r.kautenburger(at)mx.uni-saarland.de

 

Kontakt und Anfahrt:

Universität des Saarlandes
Anorganische Chemie / Elementanalytik
Campus C4 1, 1. UG
66123 Saarbrücken