Thermodynamic and kinetic aspects of UO2 fuel oxidation in air at 400–2000K

An improved model to evaluate the oxidation kinetics of uranium dioxide during dry storage

“…U 4 O 9 [13,22] whereas the duration of the plateau and its value are strongly influenced [13]. Based on our model, these observations can be interpreted by considering that the diffusion coefficients of oxygen in the U 4 O 9 phase (D O U 4 O 9 ) should be independent of the burnup whereas D O U 3 O 7 should be a decreasing function of the burnup (Fig.…”

“…Hanson [13] reports that the U 4 O 9 phase is hyperstoichiometric in spent fuel with a value of the O/ U atomic ratio which can reach 2.4. Taylor [22] also reminds that the distinction between the U 4 O 9 , U 3 O 7 and UO 2+x phases becomes blurred at moderate to high burnups. This is principally due to the presence of fission products or actinides dissolved in the matrix which disturb the order at long distance from a crystallographic point of view.…”

A conceptual model for the fuel oxidation of defective fuel

“…This process has been studied because of its importance to dry storage and disposal of used nuclear fuel [90][91][92][93][94][95][96][97][98][99][100][101][102].…”

Recycling Process for Sinter-Active U3O8Powders

“…[9][10][11][12][13][14][15] The UO 2 is oxidized to U 3 O 8 via intermediate phases of U 4 O 9 and U 3 O 7 , or a mixture of these two phases. 7,9,11,[13][14][15] The formation of U 3 O 7 /U 4 O 9 on UO 2 shows diffusion-controlled kinetics and follows the discretelayer mechanism. 7,9,11) The volume contraction caused by the formation of U 4 O 9 or U 3 O 7 causes inter-or trans-granular cracks to form at the surface of the UO 2 grains.…”