ИСТИНА

The materials of containers for the disposal of radioactive waste in deep geological formations (DGR), depending on the concept adopted in different countries, are steel (including carbon and stainless steel), copper, alloys based on: chromium, molybdenum, zirconium, titanium and nickel. The Russian concept considers carbon steel, which is a well-studied material, both in physical and chemical properties. Important characteristics of carbon steels are a good combination of strength and ductility; relative predictability of its corrosion processes; low cost. However, one of its main disadvantages is low corrosion resistance. In turn, steel corrosion products can affect the mobility of long-lived radionuclides in the system of engineered safety barriers and the geological environment after their degradation. The purpose of this work is to characterize and model the composition of carbon steel corrosion products under DGR conditions, as well as to assess the behavior of Tc in the presence of corrosion products of this steel. It was found that the main products of carbon steel corrosion under the model conditions of the DGR are pyrrhotite and magnetite. The main interaction of technetium occurs with the intermediate corrosion product - ferrihydrite. After 7 days of holding the steel plate of the St3 brand in the model solution, the efficiency of Tc removal from the solution was 98.7%. Addition of iron oxidation products or reduced iron powder to barrier materials is promising for increasing the immobilization of technetium in them.