Sorption of 137Cs, 90Sr, Se, 99Tc, 152(154)Eu, 239(240)Pu on fractured rocks of the Yeniseysky site (Nizhne-Kansky massif, Krasnoyarsk region, Russia)

• Published in: Journal of environmental radioactivity 2018-12, Vol.192, p.513-523
• Main Authors: Rozov, K.B., Rumynin, V.G., Nikulenkov, A.M., Leskova, P.G.
• Format: Article
• Language: English
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2018.08.001

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 were used to study the influence of various petrographic types and fracture-filling substances on the retardation of radioactive components by different fractured rock units of Nizhne-Kansky rock massif. 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. •Based on the available geological description the intervals of depths corresponding to zones of fracturing in host-rocks have been identified.•It was demonstrated that usually fractured zones in host-rocks correspond to the contact of intrusions of dolerites into surrounding gneiss/plagiogneiss formations. Typically, zones of fractured rocks are situated on the upper boundary of dolerites on the contact with gneiss.•There is the tight correlation between sorption distribution coefficients of Cs and Pu on fractured rocks and the implicit correlation between sorption distribution coefficients of Sr an Eu. These correlations may indicate that the retention of radionuclides are controlling mainly by sorption on biotite and calcite.•The degree of sorption is decreasing in series: rocks from shear zones → brecciated rocks → fractured and altered dolerites.•The radionuclide transport has been modeled based on the main structural domains of fractured massif. The presence of dispersed fraction in the tectonic deformation zones and their increased specific surface can increase effective retardation factors of radionuclides dramatically suppressing the effect of focusing flow on radionuclide migration.