Radiation chemistry at the heart of nuclear fuel recycling

In the current energy context, nuclear energy is experiencing a revival of interest throughout the world, due in particular to the fact that it emits very few greenhouse gases. In order to develop a clean and sustainable energy and to gain public acceptance, the recycling of certain radioactive elements of the nuclear fuel of power plants has been developed and optimized. The PUREX process has thus become the reference process for reprocessing spent nuclear fuel. Since its first industrial use in 1954, it has been based on the principle of liquid/liquid extraction of uranium and plutonium in a nitric acid medium by tributyl phosphate (TBP) dissolved in an organic solvent. To ensure the safety of the process, to replace the solvents at the optimal time, to improve the efficiency of the extraction, to increase the separation factors, and to optimize the storage of nuclear waste, a detailed understanding of the radiolytic degradation of these solvents subjected to ionizing radiation from the isotopes is necessary. This article presents the chemical mechanisms induced by ionizing radiation on these ligands, as well as the problems posed by the presence of highly reactive intermediate species and by the formation of degradation products that can accumulate in the solvents