The Effect of carbonate ion for the leaching of uranium dioxide

Moroi, Yuriko*; Kirishima, Akira*; Akiyama, Daisuke*; Sato, Nobuaki*; Kitamura, Akira  ; Kimuro, Shingo   

The technical investigations of direct disposal of spent nuclear fuel are necessary for the progress of back-end strategy, which was affected by the severe accident of Fukushima No.1 Nuclear Power Plant. In this study, the effect of carbonate ion for the leaching of uranium dioxide, which is the main component of spent nuclear fuel, was tested by the batch experiment. The leaching tests carried out in Ar gas atmosphere in glove box and sodium dithionite was used as reductant to simulate the deep underground environment. As a result, the leaching of uranium dioxide was clearly promoted by the carbonate ion. In addition, the dissolution rate of uranium also increased with the concentration of carbonate ion.