On the solubility of chromium sesquioxide in uranium dioxide fuel

Chromium sesquioxide doped uranium dioxide systems with a variety of initially added Cr2O3 amounts were prepared under different sintering conditions. The solubility limit of Cr for each sintering condition is derived from the measured content of the dopant dissolved in the UO2 matrix using electron probe microanalysis (EPMA). It is found that the solubility of chromium in a uranium dioxide system for these series sintered at 1600, 1660 and 1760 °C is limited to respectively 0.065±0.002, 0.086±0.003 and 0.102±0.004 wt% Cr. The lattice parameters of the different Cr2O3 doped fuels have been examined with X-ray diffraction (XRD). The XRD peaks of the samples sintered at 1760 °C as well as a UO2 reference without Cr, prepared under the same conditions, were measured and a value for the lattice parameter a for each sample was obtained using the unit cell refinement method. A slight contraction of the lattice parameter is observed with increasing dopant content.