Abstract: The tail gas with high-concentration of nitrogen oxides (NO_x) produced during the spent fuel retreatment process in the nuclear power industry is not only a key target for the control of radioactive pollutants but also a nitrogen resource with recycling value. This paper systematically reviews the key links of the NO_x recovery technology system in the post-treatment scenario: Firstly, the removal methods for characteristic radioactive impurities in the exhaust gas, especially fission products such as ruthenium-106; Secondly, the drying process of nuclear-grade tail gas was summarized, emphasizing the significance of deep drying (dew point < -70℃) for the subsequent separation system. The energy efficiency and applicable scenarios of solvent absorption, deep condensation dehydration, adsorbent adsorption, and membrane separation were compared. Furthermore, the core technologies for NO_x enrichment and separation were elaborated in detail, including the low-temperature absorption method with nitric acid solution (0—5℃) and the selective adsorption of zeolite adsorbents. The industrial value of these two methods in the preparation of high-purity liquid N₂O₄ (purity >99.9%) was pointed out, providing technical support for the safe disposal and resource utilization of tail gas from spent fuel after-treatment. In the future, it is necessary to focus on developing new separation materials that are resistant to acid and radiation aging to enhance the economic efficiency and stability of the process.

Key words: spent fuel reprocessing, recovery of nitrogen oxides, removal of radioactive impurities, gas dehydration, pressure swing adsorption