ISO 12795:2004 核燃料技術—二酸化ウランの粉末とペレット—不純物補正を伴う重量分析法によるウランと酸素/ウラン比の測定 | ページ 2

Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 12795 was prepared by Technical Committee ISO/TC 85, Nuclear energy, Subcommittee SC 5, Nuclear fuel technology.

1 Scope

This International Standard specifies a method of determining the mass fraction of uranium and the oxygen-to-uranium atomic ratio in hyperstoichiometric uranium dioxide (UO_{2+ X} ) powders and pellets.

This International Standard is used for the determination of the U mass fraction and the O/U-ratio of nuclear grade uranium dioxide. The precision and accuracy stated in 8.2 are valid, if the total amount of impurities in the sample does not exceed the figures given in 8.2.

An impurity correction in the U mass fraction and the O/U-ratio determination should be performed, if the amount of total impurities in oxide form exceeds 1 500 µg per gram of sample. Lower impurity levels influence the O/U-ratio by less than 0,000 5 and can be neglected. The non-volatile impurities shall be determined by an appropriate technique, and the correction applied. If the total content of the non-volatile impurities in oxide form is greater than 1 500 µg per gram of sample, the overall precision of the method depends on the accuracy of these impurity measurements.

If no impurity correction is made and if the enrichment of the sample is not considered as described in 8.11, the precision and accuracy figures will be poorer than in 8.2.

Bibliography