Technical Report NTB 23-04
Solubility Limits for Betonite Near Field (Update of NTB 14-06)
Solubility limits for the 29 elements Ac, Ag, Am, C, Ca, Cf, Cl, Cm, Cs, Ho, I, Mo, Nb, Ni, Np, Pa, Pb, Pd, Po, Pu, Ra, Se, Sm, Sn, Sr, Tc, Th, U, Zr have been calculated in bentonite porewater using the PSI Chemical Thermodynamic Database 2020 (TDB 2020) (Hummel & Thoenen 2023) with the most recent version of GEM Software (GEMS, https://gems.web.psi.ch/).
The majority of these 29 elements exhibit maximum solubilities below the micromolar range. The solubilities of Ca, Sr and inorganic carbon are determined by the definition of the porewater itself and Cs, Cl and I are chemically “unlimited”.
The solubility limits calculated using TDB 2020 can be considered in the safety assessments “as they are” as great care has been taken in the development of TDB 2020 that any lack of data may lead to overestimations but never to grossly underestimated solubilities.