UNE-EN ISO 22765:2025

This document describes the ceramographic procedure used to prepare sintered (U,Pu)O2 pellets for

qualitative and quantitative examination of the (U,Pu)O2 pellet microstructure.

The examinations are performed:

before any treatment or any etching;

after thermal treatment or after chemical or ion etching.

They allow:

observation of any cracks, intra- and intergranular pores or inclusions, and

measurement of the grain size, porosity and plutonium homogeneity distribution.

The mean grain diameter is measured by one of the classic methods: counting (intercept method),

comparison with standard grids or typical images, etc[2]. The measurement of individual grain sizes

requires uniform development of the microstructure over the entire specimen.

The plutonium cluster and pore distribution and localization are generally analysed by automatic

image analysis systems. The plutonium distribution is usually revealed by chemical etching or by alpha

autoradiography. A scanning electron microscope or a microprobe could also be used. In this case an

additional preparation could be needed depending on the equipment. This preparation is not in the

scope of this standard.