Abstract
The study demonstrates the effect of sorption properties of fractured host rocks from the Yeniseysky site (Nizhne-Kansky rock massif, Krasnoyarsk region) on the migration of dissolved radioactive components (137Cs, 90Sr, 79Se, 99Tc, 152(154)Eu, 239(240)Pu) in the deep geological conditions of a high-level radioactive waste repository. Estimates of radionuclide distribution coefficients between the aqueous solution and fractured rocks obtained from sorption experiments. The influence of various petrographic types and fracture-filling substances on the retardation of radioactive components has been investigated. Based on the results of sorption experiments, we concluded that the type and attributes of rock discontinuities, as well as the mineral composition of the material in fractures, are crucial for the immobilization of radionuclides during their migration through a geological environment.
Highlights
There is a project plan for the construction of a deep underground research facility in the gneissic Nizhne-Kansky rock massif (Krasnoyarsk region, Russia) to investigate the physical-chemical processes in the system “vitrified high-level radioactive waste–artificial barriers–surrounding host rock”
We considered an area confined to faults and fractures in rocks, assuming that the sorption of radionuclides is occurring predominantly on fracture surfaces or on the material which fills the interspace of fractures and on brecciated and mylonitized material from shear zones
The study showed that fractured zones in host rocks most often correspond to the contact of intrusions of dolerites into surrounding gneiss/plagiogneiss formations
Summary
There is a project plan for the construction of a deep underground research facility in the gneissic Nizhne-Kansky rock massif (Krasnoyarsk region, Russia) to investigate the physical-chemical processes in the system “vitrified high-level radioactive waste–artificial barriers–surrounding host rock”. There are scarce and unstructured data about the sorption properties of the host rocks at the Yeniseysky site of the Nizhne-Kansky massif and there is no comprehensive comparison of the retention capacities of rocks in this region. The aim of our study is to obtain data of sorption experiments with the interaction of contaminated groundwater with host rocks at the Yeniseysky site and to understand how these rocks govern the behavior of radionuclides. It was assumed that the preferential pathways of contaminated groundwater flows are areas with high permeability, i.e. fractured rocks. The study demonstrated that both mechanisms must be taken into account through effective (combined) retardation coefficients (factors) for application in solute transport modeling
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