Spent fuel reprocessing is a key part of the nuclear fuel cycle and a bottleneck that restricts the sustainable development of nuclear power. With the help of powerful external neutrons in the accelerator drive system, spent fuel with some fission products removed can be prepared as regenerated nuclear fuel for combustion and value addition. The high-temperature oxidation and evaporation technology can be used to separate and remove the volatile fission products in spent fuel, and the rare earth elements in the fission products generally have a large neutron absorption cross section, known as neutron poisons, which seriously affects the transmutation of minor actinides. , Must be effectively separated and removed. The chemical properties of lanthanides and actinides are very similar, and their separation has always been one of the hot issues in the field of spent fuel reprocessing.
The Transmutation Laboratory of the Institute of Modern Physics, Chinese Academy of Sciences, in cooperation with Tsinghua University, has adopted a green and environmentally friendly acidic functionalized ionic liquid [Hbet] [Tf2N] as the separation medium, and has developed a simple post-treatment technology for selective dissolution separation, which The post-processing methods of spent fuel are different. The concentrated fuel is not used to completely dissolve the spent fuel. Only the fission products such as neutron poisons are effectively separated and removed by selective dissolution. The actinides uranium, plutonium and neptunium that can be recycled are realized. Separated from the group of americium. And through theoretical calculations, it is proposed that the solubility of metal oxides has a certain correlation with its own lattice energy, thus revealing the nature of the dissolution of metal oxides. The figure below is a schematic diagram of the selective dissolution separation process and the relationship between the dissolution essence of the metal compound and the lattice energy of the metal oxide.
This method avoids the large amount of strong acid high-level radioactive waste liquid generated by the traditional spent fuel dissolution process, reduces radioactive pollution to the environment, reduces the total amount of nuclear waste, and has a simple process flow. This research provides a simple and efficient way to separate fission products such as neutron poisons for spent fuel reprocessing. It will help solve the problem of the separation of lanthanum and actinium in spent fuel reprocessing, and can broaden the research of spent fuel reprocessing The method is expected to improve the key technological process of spent fuel reprocessing in China and provide technical reserves for the implementation of advanced fuel closed cycle in China.
The research results were published in the international chemistry journal Inorganic Chemistry. This work was supported by the Chinese Academy of Sciences ’Pilot Project and the Western Light Young Scholars Program.
Figure: Schematic diagram of the selective dissolution separation process and the relationship between the nature of dissolution and the lattice energy of the metal oxide
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