Profile of a near-surface storage facility for solid radioactive wastes from uranium production

Relevance. Near-surface storage facilities for solid radioactive wastes from uranium industry enterprises pose a potential threat to the environment. Therefore, solving the problem of conditioning sludges placed in these storages is an important ecological task. At the same time, radioactive wastes are a promising technogenic source of uranium, so the technology for sludges processing should include the possibility of uranium extraction. First, this task requires a detailed study of the wastes composition and forms of uranium state in sludges. Aim. To determine the phase and chemical composition of solid radioactive wastes of the near-surface storage facility of Chepetsky Mechanical Plant SC, to establish the storage facility profile, uranium concentration zones and forms of its state in the wastes. Methods. X-ray diffraction phase and X-ray fluorescence analysis, inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry, scanning electron microscopy and electron probe microanalysis. Results and conclusions. The near-surface storage facility consists of three sites. The thickness of the upper screening soil layer is 3–3.5 m, this layer more than 59 wt % consists of SiO2. Four types of solid radioactive wastes are located on the storage territory. Uranium production sludges, consisting mainly of gypsum (58–88 wt %), are placed in the Site 1 (depth 3–7 m) and the Site 2 (depth from 3.5–4.5 to 7 m). Uranium production wastes, consisting of 81–89 wt % SiO2, are located within Site 3 (depth 4–7 m). Calcium production sludges are placed in the southern part of Site 2 and on the territory of Site 3 above the uranium wastes. The main compound of these sludges is CaCO3 (60–95 wt %). The zirconium production sludges consist mainly of CaCO3 (53–67 wt %) and CaF2 (23–32 wt %) and are disposed in the northern part of Site 2 above the uranium wastes layer. Uranium is contained throughout the entire volume of the storage wastes and is unevenly distributed. Its average content ranges from 0.006 to 0.498 wt %. depending on the location. Uranium is present in sludges both as part of the main components and in the form of its own mineral phases. The wastes are comparable to poor ores in terms of uranium content, so we can consider these sludges as a technogenic source of this metal.