ESTRAL - Realistic Integration of Sorption Processes in Transport Programs for Long-term Safety Analysis

In safety assessments for radioactive waste repositories in deep geological formations the host formation and/or the sedimentary overburden might act as a barrier, since sorption on mineral surfaces of the sediments can retard the transport of many radionuclides. So far, the retention of radionuclides has been described in respective computer programs by temporally constant distribution coefficients.
A coupling of reactive transport programs with a full geochemistry code is currently not practical due to the high computing costs for the calculation of large model areas and very long time scales as required in long-term safety analysis. Therefore, the present study develops and implements a different methodology to extend the existing 3D transport program r3t [FEI 04] towards a more realistic description of the radionuclide migration under temporal variable geochemical conditions. Such changes might be caused in a sedimentary overburden by a marine transgression or the thawing of permafrost.