Measurement of energy spectra on irradiated polycrystalline UO₂ samples using secondary ion mass spectrometry

The energy spectrum of uranium in irradiated fuels is known to give key information on the oxidation state of uranium at the sample surface. In this respect, it is essential to know the operating conditions applied to measure energy spectra by secondary ion mass spectrometry in order to obtain reliable data. Using a focussed beam on CAMECA IMS6f, the acquisition of an energy spectrum is performed along a line on the sample surface because the primary beam position moves as a function of the high voltage. Depending on the size of UO₂ grains, the analysed area can be limited within one single grain or spread among many grains. The consequences of such acquisition conditions are discussed in this paper. (authors)