There is increase of radionuclide migration capacity (by 200 - 500 times) with underground waters when pH > 9.5 (period III). In addition, percent of soluble fraction of 90Sr is growing from 50 to 98 % of total activity of 90Sr. According to thermodynamic modeling, part of migration fraction of 90Sr in compound with carbonates is growing from 3 % (period II with pH 8.5 - 9.5) to 14 % (period III). At the same time, percent of migration form 90Sr of free ion decreases to 83 % in period III. The results of thermodynamic modeling doesn`t explain significant increase of strontium- 90 concentration. As is known, strontium and calcium compound with carbonate, strontianite (SrCO3) and calcite (Ca- CO3), are slightly soluble in water and when formed, they fall into a precipitate. Perhaps 90Sr forms other complex compounds that are not sorbed by soils and are not found by applications for thermodynamic simulation. High pH values are formed by contacting infiltration and groundwater with concrete deepened structures of buildings. In the case of pH increase of groundwater to a value of 9.5 – 10.0, due to the corrosion of the concrete of the foundation of the ARKA, which overlaps the part of the aquifer, is possible a significant increase in volumetric activity of 90Sr, uranium, and transuranic elements. The article presents recommendations for reducing the level of radioactive contamination of groundwater.
Keywords: ChNPP industrial site, underground waters, 90Sr, uranium, transuranic elements, basic ions, pH, migration.
Panasyuk М. І., Lytvyn І. А. Laws of distribution of uranium in groundwater of Chnpp industrial site // Jaderna fizuka ta energetuka. – 2017. - Vol. 18, № 1. - C. 56 - 62.