Oxidative uranium dissolution from UO in the presence of adsorbed phthalic acid

Kumagai, Yuta; Jonsson, M.*

no journal, , 

Contact of water with spent nuclear fuel is anticipated in scenarios of failure of the repository system for the direct disposal of spent fuel. Upon the direct contact of water, the UO matrix of the fuel is expected to gradually dissolve due to oxidation of uranium by the action of ionizing radiation. In this study, we examined effects of organic acid on the UO dissolution by using phthalic acid as a model compound. We investigated oxidation of UO by exposure to HO in aqueous solution containing phthalic acid. Significant adsorption of phthalic acid on UO was observed. The coverage of the surface was estimated to reach 80 %. The HO-exposure experiments revealed that adsorbed phthalic acid has no significant effect on the redox reaction by HO on the UO surface, despite the high surface density. HO oxidation of UO with adsorbed phthalic acid resulted in U dissolution to similar extents with the U dissolution measured in aqueous bicarbonate solutions.