Recent progress in separation of technetium-99 from spent nuclear fuel and radioactive waste. Challenges and prospects

The development of methods for the selective binding and separation of pertechnetate anion from aqueous solutions formed during the reprocessing of spent nuclear fuel remains an extremely urgent task. The lack of acceptable solutions of this problem has become one of the main obstacles to the development of nuclear energetics as one of the main sources of energy not related to emissions of carbon dioxide into the atmosphere. This review discusses recent advances in the creation of effective and highly selective receptors on TcO4−, as well as extractants and sorbents allowing the binding of this anion in aqueous solutions, including in highly aggressive environments. Various approaches solving this problem are analyzed critically. They include precipitation and reductive precipitation of TcO4−, its extraction in two-phase water/organic solvent systems, methods of binding TcO4− on inorganic, composite and organic sorbents of different types, as well as the extraction and sorption characteristics used in this case. The collected data and the results of their discussion can contribute to a deeper understanding of ways to solve remaining unsolved problems in this area and planning directions for its further development.