Study on the Dissolution Behavior of UO₂ in the Na₂CO₃–H₂O₂ System Using a Flow-Through Dissolution Device

Abstract

The CARBEX process, proposed in 2008, is a spent nuclear fuel (SNF) reprocessing process that relies on the alkaline environment of a Na 2 CO 3 −H 2 O 2 system. In this work, we focused on the dissolution stage of the CARBEX process using a flowthrough dissolution device to investigate the dissolution behavior of UO 2 in the Na 2 CO 3 −H 2 O 2 system and provide the dissolution rates of UO 2 under different concentrations of Na 2 CO 3 and H 2 O 2 . In addition, the 60 Co-γ radiation source was used to simulate the radioactive environment during spent fuel reprocessing and to investigate the effect on the UO 2 dissolution behavior in irradiation. The results show that the radiolysis products of water molecules react with excess H 2 O 2 in solution to further generate • HO 2 . At the same time, H 2 O 2 can also quench reductive radioactive dissolution products, increasing the oxidizing nature of the solution and thereby enhancing the dissolution rate of UO 2 in a Na 2 CO 3 −H 2 O 2 system. Finally, the dissolution process of UO 2 in the Na 2 CO 3 −H 2 O 2 system under irradiation conditions was summarized.