TY - JOUR
T1 - A cement degradation model for evaluating the evolution of retardation factors in radionuclide leaching models
AU - Jacques, Diederik
AU - Perko, Janez
AU - Seetharam, Suresh
AU - Mallants, Dirk
N1 - Score = 10
PY - 2014/10
Y1 - 2014/10
N2 - Cement-based disposal systems for radioactive will undergo chemical alterations due to interaction with the environment. One of the most relevant geochemical alteration processes is decalcification or leaching of the cement phases. Consequently, the cementitious components will evolve through different chemical degradation states, altering physical and chemical parameters. This paper presents an approach in which geochemical modelling serves as a basis for assessing the evolution of geochemical conditions within a cement-based near-surface disposal facility. Geochemical modelling is used to quantify uncertainties related to C–S–H leaching. On the other hand, the concept of mixed tank reactor is used to represent cement degradation within the entire disposal system and linked it with the retardation factor. The usefulness of the approach is demonstrated via a number of case studies concerning leaching of radionuclides from a cementitious disposal facility. The studies reveal that there is a large effect of the conceptualisation on calculated fluxes from the disposal facility. A crucial factor is the amount of radionuclide mass present in the disposal system when large changes in the retardation factor occur, for instance, when different retardation factors exist in different chemical degradation states.
AB - Cement-based disposal systems for radioactive will undergo chemical alterations due to interaction with the environment. One of the most relevant geochemical alteration processes is decalcification or leaching of the cement phases. Consequently, the cementitious components will evolve through different chemical degradation states, altering physical and chemical parameters. This paper presents an approach in which geochemical modelling serves as a basis for assessing the evolution of geochemical conditions within a cement-based near-surface disposal facility. Geochemical modelling is used to quantify uncertainties related to C–S–H leaching. On the other hand, the concept of mixed tank reactor is used to represent cement degradation within the entire disposal system and linked it with the retardation factor. The usefulness of the approach is demonstrated via a number of case studies concerning leaching of radionuclides from a cementitious disposal facility. The studies reveal that there is a large effect of the conceptualisation on calculated fluxes from the disposal facility. A crucial factor is the amount of radionuclide mass present in the disposal system when large changes in the retardation factor occur, for instance, when different retardation factors exist in different chemical degradation states.
KW - Surface disposal
KW - cement degradation
KW - leaching
KW - radionuclide transport
KW - impact assessment
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/ezp_138202
UR - http://knowledgecentre.sckcen.be/so2/bibref/12211
U2 - 10.1016/j.apgeochem.2014.06.008
DO - 10.1016/j.apgeochem.2014.06.008
M3 - Article
SN - 0883-2927
VL - 49
SP - 143
EP - 158
JO - Applied Geochemistry
JF - Applied Geochemistry
IS - 10
ER -