Dissolution of uranium oxides under alkaline oxidizing conditions

Bench scale experiments were conducted to determine the dissolution characteristics of UO 2 , U 3 O 8 , and UO 3 in aqueous peroxide-containing carbonate solutions. The experimental parameters investigated included carbonate countercation (NH 4 + , Na + , K + , and Rb + ) and H 2 O 2 concentration. The carbonate countercation had a dramatic influence on the dissolution behavior of UO 2 in 1 M carbonate solutions containing 0.1 M H 2 O 2 , with the most rapid dissolution occurring in (NH 4 ) 2 CO 3 solution. The initial dissolution rate ( y ) of UO 2 in 1 M (NH 4 ) 2 CO 3 increased linearly with peroxide concentration ( x ) ranging from 0.05 to 2 M according to: y = 2.41 x + 1.14. The trend in initial dissolution rates for the three U oxides under study was UO 3 ≫ U 3 O 8 > UO 2 .