Assessment of geochemical barriers at preservation of low-level radioactive waste storages

Abstract

The work considers geochemical aspects of the natural and man-made system for storing radioactive waste (RW) from one of the Siberian enterprises of the fuel and nuclear cycle. Careful geochemical testing of key sites of the system allows us to identify geochemical barriers that prevent the spread of uranium outside the sludge storage. In addition, experiments were conducted on the leaching of the sludge material in the laboratory using modern methods for determining the composition of solutions and solid phases, as well as experiments on uranium sorption on the main types of subsoil. Experimental and thermodynamic modeling of uranium deposition processes confirms that the system studied satisfactorily copes with the absorption of uranium taken out of the sludge storage due to dilution and sorption on rocks and bottom sediments. Particularly favorable are bottom sediments rich in organic matter, which bind uranium to organic-mineral complexes.

Application of mineral and organic modifications of peat near the sludge storage facility for uranium immobilization

“…Since the beginning of the plant operation in 1950-1951, over 100.000 tons of low activity solid wastes have been accumulated in its sludge pond. Over the 65-year facility history, the area of the sludge repositories had been permanently polluting the groundwater with sulfate and nitrate anions, uranium, and a number of heavy metals [10]. The tailing pond of the plant is located in the Pashenka river valley bottom, in the upper part of the dammed boggy area.…”

“…For a long time, the atmospheric sediments, filtrated through the walls and bottom of the tailing pond and enriched with heavy metals and radioactive elements, entered a lowland swamp to form a multi-element geochemical anomaly. The detailed characteristics of the chemical composition of the water and deposits in the territory are presented in the author's previous works [10][11][12].…”