Thermal recovery and lattice expansion of self-irradiated U0.80Am0.20O2-x, an in situ high temperature x-ray diffraction study

The thermal recovery of self-irradiated and damaged U0.80Am0.20O2-x solid solution has been studied in situ using high-temperature x-ray diffraction between 25 degrees C and 1300 degrees C. The cumulative alpha decay dose of the damaged material was equal to 2.2 displacements per atom, leading to a lattice expansion of 0.31%. This value is close to the saturated lattice expansion of self-irradiated polycrystalline UO2 and AmO2. The thermal recovery process is characterized by three stages, as revealed by the temperature derivative of the lattice parameter showing two maxima at 600 degrees C and 1000 degrees C. The thermal recovery is completed at about 1200 degrees C. These data are compared with existing studies on other oxide fuels. In addition, the lattice expansion of the damaged U0.80Am0.20O2-x sample is also discussed and compared to that of defect free UO2, NpO2 and AmO2 materials. The thermal energy necessary to initiate the annealing of the defects is reached at about 400 degrees C, whilst at 1100 degrees C, a defect free U0.80Am0.20O2-x sample is obtained. (C) 2013 Elsevier Inc. All rights reserved.