The disposal of low-level radioactive waste at uranium ore mining and processing sites is currently considered unsafe due to complex pollution near uranium sludge storage facilities. The relevance of this study is related to the need to search for possible ways to remove uranium from migration in water flows to minimize the harm from the release of nuclear fuel to the environment. One of the ways to study the radionuclide species in water is the use of the cascade filtration method, whereby a water sample issequentially filtered through a set of membranes with decreasing pore size.
In this work, we collected samples of surface and groundwater in the area near the sludge storage of the Novosibirsk Chemical Concentrates Plant. The concentrations of HCO3- and Cl- were determined using the titrimetric method, while the concentration of SO42- was measured using the turbidimetric method. To determine the concentration of cations and trace elements, the ICP MS method was used. The uranium species were determined using the method of cascade fractionation using Sartorius vacuum filter systems and membranes with pore sizes of 1.2, 0.45, 0.2, 0.1, and 0.05 microns.
As a result of the experiments, it was established that when uranium enters water flows, the leading form of migration is suspensions (1.2-0.45 µm) and large colloids (0.22-0.45 µm). At a sufficiently high concentration of bicarbonate in waters, uranyl-carbonate complexes are formed. With increasing distance from the sludge storage site, as a result of water dilution, sorption and sedimentation processes, the uranium concentration decreases, the pH value increases, while the Eh decreases, and the geochemical situation is reduced. As a result, carbonate complexes with uranium break down; part of the uranium passes into sediment, forming uranium oxide; and suspensions and large colloids again become the leading form of transport.
