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Kumagai, Yuta; Fidalgo, A. B.*; Jonsson, M.*
Journal of Physical Chemistry C, 123(15), p.9919 - 9925, 2019/04
Times Cited Count:20 Percentile:63.7(Chemistry, Physical)Radiation-induced oxidative dissolution of uranium dioxide (UO) is one of the most important chemical processes of U driven by redox reactions. We have examined the effect of UO stoichiometry on the oxidative dissolution of UO induced by hydrogen peroxide (HO) and -ray irradiation. By comparing the reaction kinetics of HO between stoichiometric UO and hyper-stoichiometric UO, we observed a significant difference in reaction speed and U dissolution kinetics. The stoichiometric UO reacted with HO much faster than the hyper-stoichiometric UO. The U dissolution from UO was initially much lower than that from UO, but gradually increased as the oxidation by HO proceeded. The -ray irradiation induced the U dissolution that is analogous to the kinetics by the exposure to a low concentration (0.2 mM) of HO. The exposure to higher HO concentrations caused lower U dissolution and resulted in deviation from the U dissolution behavior by -ray irradiation.
Kumagai, Yuta; Fidalgo, A. B.*; Jonsson, M.*
no journal, ,
We have investigated the effect of UO-hyper-stoichiometry on the oxidative dissolution upon HO exposure and by water radiolysis. The oxidative dissolution of UO is anticipated in the concept of geological disposal of spent nuclear fuel and also in the direct contact with coolant water after a severe accident. However, our understanding on the dissolution kinetics has so far not taken the hyper-stoichiometric nature of UO into account. Thus, we have studied the oxidative dissolution of hyper-stoichiometric UO and stoichiometric UO and compared the results. The results show that the UO stoichiometry largely affects the kinetics of oxidative dissolution. The oxidation of stoichiometric UO in water proceeded fast accompanied with low initial U dissolution, but gradually the reaction became slower and U dissolution became more significant.