Oxidative dissolution of ADOPT compared to standard UO₂ fuel

In this work we have studied oxidative dissolution of pure UO₂ and ADOPT (UO₂ doped with Al and Cr) pellets using H₂O₂ and gammaradiolysis to induce the process. There is a small but significant difference in the oxidative dissolution rate of UO₂ and ADOPT pellets, respectively. However, the difference in oxidative dissolution yield is insignificant. Leaching experiments were also performed on in-reactor irradiated ADOPT and UO₂ pellets under oxidizing conditions. The results indicate that the U(VI) release is slightly slower from the ADOPT pellet compared to the UO_2. This could be attributed to differences in exposed surface area. However, fission products with low UO₂ solubility display a higher relative release from ADOPT fuel compared to standard UO₂-fuel. This is attributed to a lower matrix solubility imposed by the dopants in ADOPT fuel. The release of Cs is higher from UO₂ which is attributed to the larger grain size of ADOPT. - Highlights: •Oxidative dissolution of ADOPT fuel is compared to standard UO₂ fuel. •Only marginal differences are observed. •The main difference observed is in the relative release rate of fission products. •Differences are claimed to be attributed to a lower matrix solubility imposed by the dopants in ADOPT fuel.