Research on the degradation mechanism, product effects and optimization strategy of the tributyl phosphate solvent system in the PUREX process

While nuclear energy represents a low-carbon and high-efficiency energy source that plays a vital role in the global energy mix, the limitations of spent fuel reprocessing technology pose a major challenge to its sustainable development. The PUREX (plutonium uranium redox extraction) process is currently the dominant nuclear fuel reprocessing technology in the world. However, the key extractant in this process is tributyl phosphate (TBP), which degrades under intense radiation, high temperatures, and strong acidity. This leads to the production of dibutyl phosphate, monobutyl phosphate, and other degradation byproducts, which may reduce the extraction efficiency and trigger third-phase formation and equipment corrosion. This paper systematically reviews the degradation mechanisms of TBP and its diluents, the analytical technique suitable for characterizing degradation products, and the impact of degradation products on the post-treatment process. Additionally, optimization strategies employed for suppressing third-phase formation are discussed. This study offers a theoretical foundation and technical insights in optimizing the PUREX process and ensuring the safe operation of the post-treatment process.