ISO 22765:2025 核燃料技術 — 焼結 (U,Pu)O2 ペレット — 微細構造検査のためのセラモグラフィーによる準備に関するガイダンス | ページ 2

Foreword

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This document was prepared by Technical Committee ISO/TC 85, Nuclear energy, nuclear technologies, and radiological protection, Subcommittee SC 5, Nuclear installations, processes and technologies, in collaboration with the European Committee for Standardization (CEN) Technical Committee CEN/TC 430, Nuclear energy, nuclear technologies, and radiological protection, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This second edition cancels and replaces the first edition (ISO 22765:2016), which has been technically revised.

The main changes are as follows:

• Clause 1, additional comments about equipment and preparation;
• Clause 4, addition of required steps according to analyses to be carried out;
• Clauses 7 and 8, update of the parameters used for polishing.

A list of all parts in the ISO 22765 series can be found on the ISO website.

1 Scope

This document is applied to fuel fabrication. It 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

• a) before any treatment or any etching, and
• b) 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 (SEM) or a microprobe can also be used. In this case an additional preparation can be needed depending on the equipment used. This preparation is not in the scope of this standard.

2 Normative references

There are no normative references in this document.

3 Terms and definitions

No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

Bibliography