Long-term geochemical evolution of the near field repository: Insights from reactive transport modelling and experimental evidences

A comparative study of mud‐like and coralliform calcium carbonate gallbladder stones

“…As an inorganic salt, CaCO 3 can form three homogeneous polycrystal in nature, including calcite, aragonite and vaterite (Cantaert et al, ; Liu, Liu, Su, & Shen,, ; Pouget et al, ; Song, Cölfen, Xu, Hartmann, & Antonietti, ). These three kinds of homogeneous polycrystalline CaCO 3 have different atomic arrangement, and can form particles with different morphologies and symmetries (Arcos et al, ). CaCO 3 of different crystalline forms have significantly different physical properties (Killian et al, ), thermal properties (Huang et al, ), optical properties (Aizenberg, Tkachenko, Weiner, Addadi, & Hendler, ) and electrical properties.…”

Anion capture with calcium, aluminium and iron containing layered double hydroxides

“…However, it should be pointed out that the concentration of carbonate ion, which cause conversion into carbonate in 14 days was much higher than the expected carbonate ion concentrations in water percolating a geological storage site. For example, if the water percolates through bentonite, the carbonate concentration is only expected to be of the order of tens of milimoles per liter [14] whereas decomposition was observed for CO 3 2-concentrations in excess of 0.125 M only. Moreover, such decomposition would not be as problematic for any 14 C captured, as it would in all probability be incorporated in the calcium carbonate that forms during decomposition of the layered double hydroxides.…”

“…For example, if the water percolates through bentonite, the carbonate concentration is only expected to be of the order of tens of milimoles per liter [14] whereas decomposition was observed for CO 3 2-concentrations in excess of 0.125 M only. Moreover, such decomposition would not be as problematic for any 14 C captured, as it would in all probability be incorporated in the calcium carbonate that forms during decomposition of the layered double hydroxides. It will nevertheless be important to study the limits of the stability further in future work.…”

RTM for Waste Repositories

“…In HLW disposal concepts, the bentonite buffer surrounding waste packages will evolve with time due to progressive reaction with saturating ambient groundwater, including ion exchange, dissolutionprecipitation of accessory (gypsum, halite quartz, calcite) and clay minerals potentially affecting properties such as the hydraulic conductivity and the swelling pressure. RTM studies regarding these aspects have evolved from simple exchange models to more complex 1-and 2-D problem setup, including the effect of advection in a fracture intersecting the disposal cell (e.g., Arcos et al 2003Arcos et al , 2008Sena et al 2010;Benbow et al 2019).…”