Radioactive waste

2023: Russia has created a new class of solvents for the processing of nuclear waste

On July 11, 2023, Russian researchers from Lomonosov Moscow State University (MSU) announced the development of a new class of solvents for the processing of nuclear waste.

When the nuclear reactor stops working, radionuclides of varying degrees of activity remain in it. In Russia, reprocessing is implemented according to the closed nuclear fuel cycle scheme: fuel is removed from the reactor, then uranium and plutonium are released for reuse, and the remaining elements are transferred to safe burial forms. But not all radionuclides can be recycled in the same way.

Russia has created a new class of solvents for the processing of nuclear waste

One of the components, americium, we can "burn out" in a fast neutron reactor. It turns into other shorter-lived radionuclides that are easier to dispose of. But together with Americium in SNF (spent nuclear fuel) there are lanthanides - neutron poisons. They reduce the efficiency of the reactor, "says Ekaterina Konopkina, author of the work, junior researcher at the Department of Radiochemistry, Faculty of Chemistry, Moscow State University.

To solve the problem, it is proposed to divide highly active waste into fractions with similar chemical or nuclear-physical properties. This helps to select a matrix to immobilize radionuclides and safely bury them. One way to separate several elements is by liquid extraction of metal ions from the solution using organic compounds, ligands. The efficiency of the process directly depends on the structure of the ligand and the mechanism of its interaction with the ion.

The authors of the project propose to use ligands based on pyridine modified with phosphorus - pyridine diphosphonates. Compared to other compounds, they are easier to synthesize and have sufficient selectivity. Pyridine diphosphonates are said to be another step towards multicomponent selective extraction systems.^[1]

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