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 Na₂CO₃–H₂O₂ system. In this work, we focused on the dissolution stage of the CARBEX process using a flow-through dissolution device to investigate the dissolution behavior of UO₂ in the Na₂CO₃–H₂O₂ system and provide the dissolution rates of UO₂ under different concentrations of Na₂CO₃ and H₂O₂. In addition, the ⁶⁰Co-γ radiation source was used to simulate the radioactive environment during spent fuel reprocessing and to investigate the effect on the UO₂ dissolution behavior in irradiation. The results show that the radiolysis products of water molecules react with excess H₂O₂ in solution to further generate ^•HO₂. At the same time, H₂O₂ can also quench reductive radioactive dissolution products, increasing the oxidizing nature of the solution and thereby enhancing the dissolution rate of UO₂ in a Na₂CO₃–H₂O₂ system. Finally, the dissolution process of UO₂ in the Na₂CO₃–H₂O₂ system under irradiation conditions was summarized.