Radionuclides and Toxic Species Reactive Transport in Cement-Based Materials for Nuclear Waste

The transfer of radionuclides from radioactive waste is one of the major concerns of ensuring the safety of nuclear waste disposal. Cement-based materials (such as grout, cement paste, mortar, or concrete) are widely considered in nuclear waste disposal as engineer barriers for the conditioning of low – and intermediate – level radioactive waste.

Migration investigations in cement-based materials is therefore highly relevant to acquire robust experimental datasets and to obtain a precise determination of reactive transport properties. However, a predicting description of the radionuclide migration is complicated to access considering the large panel of physicochemical conditions (e.g. pH, ionic strength, carbonation, temperature, water saturation, presence of organic complexing agents, redox potential etc.) and cement-material composition, which can occur in radioactive waste disposal.

Experimental data are needed to allow the construction of robust predictive transport models, including the physicochemical mechanisms that may be involved in the evolution of a radioactive waste package in cementitious media. Because of the low diffusivity and high sorption capacity of cement-based material, such data are still missing in literature, especially for species at very low concentrations or for emerging or alternative cementitious materials. The goal of this Research Topic is to centralize relevant studies dealing with radionuclide reactive transport in cement-based materials.

In this Research Topic, we would be interested in multi-scale experimental studies interpreted by means of predictive modeling, considering various physicochemical mechanisms.

The use of advanced and/or innovative analytical techniques would be of a great interest for this topic, for example to describe the microstructure of such porous materials.

Migration studies implying emerging or alternative cementitious systems (e.g. low pH cement, geopolymers) are also welcomed in this topic to assess a comprehensive picture of several scenarios for nuclear waste disposal.