Addition versus radiolytic production effects of hydrogen peroxide on aqueous corrosion of UO2

The electrochemical reduction of hydrogen peroxide on uranium dioxide under intermediate pH to acidic conditions

“…The absence of oxidation below this potential confirms the absence of the UO 2+x layer observed to form at higher pH. U V is the dominant surface species up to ∼0 mV when oxidation to the U VI state becomes significant, consistent with the mechanism for anodic dissolution, outlined in reactions (8) and (9).…”

“…This may be attributable to local elevated pH effects from the production of OH − by peroxide reduction, which could lead to an increase in pH near the electrode surface compared to the bulk solution value and a stabilization of the U IV U V O 2+x layer. Alternatively, a change in condition of the surface could occur for pH values <3, as observed in steady-state polarization curves [49], in chemical dissolution experiments [50] and in corrosion potential measurements in H 2 O 2 solutions [9]. However, for pH values ≤2, the cathodic behaviour is significantly modified compared to neutral conditions.…”

“…The influence of H 2 O 2 on fuel corrosion has been extensively studied [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] and much of the early literature has been reviewed [5,24]. The cathodic reduction of H 2 O 2 on UO 2 surfaces was found to proceed via a coupled chemical-electrochemical process in which H 2 O 2 chemically creates U IV -U V donor-acceptor sites on the UO 2 surface…”

Determination of the equilibrium formation constants of two U(vi)–peroxide complexes at alkaline pH

“…[4][5][6] In addition, hydrogen peroxide strongly affects the oxidative dissolution of SNF and UO 2 , by oxidizing the U(IV) of the solid to more soluble U(VI) species.…”

Radiolytic Corrosion of Uranium Dioxide: Role of Molecular Species

“…On the other hand, when water in contact with the UO 2 particles was irradiated in open to air atmosphere, no spectral modifications were observed until 21.8 kGy deposited in the solution (Figure 2) produced by water radiolysis according to the reaction (i) 14 :…”