ИСТИНА

The problem of radioactive waste utilization, in particular the safe disposal of 99Tc, is acute before the modern nuclear power industry, inasmuch as it is a long-lived radionuclide with an extremely high migration capacity of its pertechnetate ion and low sorption activity in relation to many materials. To solve this problem, various matrices were proposed for its immobilization, however, it became evident during the course of investigations that they were insufficient because of the high leaching degree of the pertechnetate ion. To increase the safety of the storage facility, it is necessary to use new materials to ensure effective and long-term immobilization of technetium as part of mineral matrices and geochemical barriers in the storage area. In the experiments the shungite from the Maxovo deposit was studied. Shungite is a black, lustrous, non-crystalline mineraloid consisting of more than 98 weight percent of carbon. It was first described from a deposit near Shunga village, in Karelia, Russia, from where it gets its name. Shungite has been reported to contain trace amounts of fullerenes (0.0001 < 0.001%). The study of kinetics showed that the onset of sorption equilibrium depends on the fractional composition of the samples and varies from 30 minutes to 4 weeks. Shungite showed a high degree of sorption in relation to pertechnetate ion. Using of scanning electron microscopy, including backscattered electrons, Raman and IR spectroscopy, the characterization of the shungite (maksovite) surface was carried out. From the data obtained, it follows that various functional groups of carbon are present on the surface of the maksovite, as well as the inclusions of pyrite, rutile and zircon. The Tc sorption by schungite-bearing rocks proceeds through a complex mechanism. Obviously, technetium is restored on pyrite due to sulfide groups, possibly, interaction with compounds of transition metals. Much of the technetium is bound by the organic constituent of the rock, an amorphous carbon that has different functional groups on the surface.