Research performed by Rosa Ester Guidone.
In the context of low and intermediate level nuclear wastes (L/ILW), cementitious materials are widely used for the conditioning and storage of the waste, as well as for the construction of the engineered barrier systems (backfill, container and liner materials). The main solid phases present in the hydrated cement can retain radionuclides present in the waste, thus preventing or slowing down their release from the disposal site. Soluble small organic molecules are expected in the repository as a component of the emplaced waste, as degradation products of organic components disposed of, but also as additives in different cement formulations. Although expectedly considered weak, the interactions of organic ligands with cement can alter the surface properties of the latter and thus need to be taken into account.
This study aims at a quantitative description of the interaction of low molecular weight organics (formate, citrate and gluconate) with selected cement phases, i.e. AFm phases, ettringite and C-S-H. In a second stage of this project, the impact of these organic ligand on the uptake of An(III)/Ln(III) (243Am, 152Eu) and An(IV) (242Pu, 238Pu) by cement and individual cement phases will be also investigated.