Characterization of Nuclear Materials in Extreme Conditions: Raman Spectroscopy Approach

A review is given of our last advances on Raman spectroscopy characterization of irradiated and/or leached UO2, PuO2 and (U, Pu)O-2 samples. For this purpose, three original Raman setups dedicated to the study of nuclear materials were involved. In every case, irradiation-induced Raman defect bands in the 500-750 cm(-1) range was observed. For UO2, an annealing temperature experiment suggests that these defect bands could be the signatures of medium-range structured defects. Besides, the leaching experiments show different behavior between the irradiated in situ probed UO2 ceramic and post mortem probed [UO2 + (U, Pu)O-2] sample: The growth of an altered layer made of studtite and schoepite phases was monitored at the surface of UO2 ceramic, while post-mortem studies reveal the presence of U3O8 and studtite phases at the surface of the UO2 grains of the binary sample. No alteration layer was observed at the surface of the leached (U, Pu)O-2 grains.