The oxides of uranium. Part IV. The system UO₂–ThO₂–O

Characterization of ThO2–UO2 pellets made by co-precipitation process

“…Lattice parameter measurements of ThO 2 -UO 2 solutions show that, within experimental accuracy, Vegard's law is obeyed. Anderson et al [38] observed that the lower limit of the stable temperature range of the ThO 2 -UO 2 solid solution phase in air lowers to 1400°C if the concentration of UO 2 is lower than 78 mol%. In the solid solution phase of UO 2 concentrations 15-78 mol%, the excess oxygen atoms are deduced to occupy the interstitial sites in the fluorite lattice.…”

Corrosion of UO2 and ThO2: A quantum-mechanical investigation

“…UO 2 and ThO 2 are the end-members of a binary system that forms a complete solid solution with the isometric fluorite structure [1]. As a result, ThO 2 can be used as fertile nuclear fuel material in light water reactors when mixed with a fissile component such as 235 U [2].…”

Analysis of the oxygen potential of Th1−yUyO2+x

“…The data of Roberts et al [7] and Anderson et al [6] refer to small values of y and slightly lower temperatures. These oxygen potentials are larger than À100 kJ mol À1 and were fitted separately.…”

“…For example, the data of Anderson et al [6] were read from a graph of the oxygen pressure versus the mean uranium valency for different values of y and T. The amount of excess oxygen x was calculated using the relation for the mean uranium valency: V U = 4 + 2x/y (see Section 3.1). The measurements of Roberts et al [7] were tabulated as the oxygen pressure versus the uranium concentration y.…”

“…The oxygen potential database of Th 1Ày U y O 2+x : (a) oxygen potential versus x (b) oxygen potential versus y (c) oxygen potential versus T. Oxygen potentials higher than À100 kJ mol À1 : (AE): Anderson et al[6]; (+): Roberts et al[7] Oxygen potentials lower than À100 kJ mol À1 : (h): Aronson and Clayton[8]; (n): Tanaka et al[9]; (s):Ugajin et al[10][11][12]; (·): Matsui and Naito for y = 1[13]; (small ·): Matsui and Naito for y = 0.2,0.4[13]; (Á): Anthonysamy et al[14].…”