Dissolution of studtite [UO2(O2)(H2O)4] in various geochemical conditions. (September 2018)

• Record Type: Journal Article
• Authors: Kim, Jungjin; Kim, HyunJu; Kim, Won-Seok; Um, Wooyong
• Is Part Of: Journal of environmental radioactivity. Volume 189(2018)
• Page Start: 57
• Page End: 66
• Publication Date: 2018-09
• Subjects: Studtite -- Dissolution -- Uranium -- Spent nuclear fuel -- Radioactive waste; Radioactivity -- Periodicals; Radiation, Background -- Periodicals; Radioecology -- Periodicals; Radioactive pollution -- Periodicals; Environmental Pollutants -- Periodicals; Radioactive Pollutants -- Periodicals; Radioactivity -- Periodicals; Radioécologie -- Périodiques; Pollution radioactive -- Périodiques; Fond de rayonnement -- Périodiques; 539.752
• DOI: 10.1016/j.jenvrad.2018.01.010
• Languages: English
• ISSNs: 0265-931X

Abstract

Abstract: This study determined the dissolution rate of studtite, (UO2 )O2 (H2 O)4, which can be formed by reaction between H2 O2 and UO2 2+ that leaks from spent nuclear fuel (SNF) in deep geological repositories. The batch dissolution experiments were conducted using synthesized studtite under different solution conditions with varying pHs and concentrations of HCO3 − and [H2 O2 ] in synthetic groundwater. The experimental results suggested that carbonate ligand and H2 O2 in groundwater accelerated the dissolution of studtite and uranium (U) release. Above 10 −5 M of H2 O2 initial concentration, the released uranium concentration in solution decreased, possibly as a result of reprecipitation of studtite due to reaction between uranium and H2 O2 . The results will be useful to assess the comprehensive transport of uranium from both nuclear waste and SNF stored in deep geological repositories. Graphical abstract: Highlights: The mechanisms of studtite dissolution by [H + ] and [OH − ] are proposed. Carbonate ligand and H2 O2 in groundwater accelerate the dissolution of studtite. Dissolved oxygen is not considered to significantly effect studtite dissolution. Dominant uranium species in 10 −3 M HCO3 − solution are confirmed using TRLFS analysis.