Nuclear fuel technology — Guidelines for ceramographic preparation of UO2 sintered pellets for microstructure examination
These examinations can be carried out before and after thermal or chemical etching.
— observations of fissures, inter- or intra-granular pores and inclusions, and
— measurement of pore and grain size and measurement of pore and grain size distributions.
The measurement of average grain size can be carried out using a classical counting method as described in ISO 2624 or ASTM E112, i.e. intercept procedure, comparison with standard grids or reference photographs.
The measurement of pore-size distributions is usually carried out by an automatic image analyser. If the grain-size distributions are also measured with an image analyser, it is recommended that thermal etching be used to reveal the grain structure uniformly throughout the whole sample.