1.1 这些试验方法包括核级二氧化铀粉末和颗粒的化学、质谱和光谱化学分析程序，以确定是否符合规范。 1.2 单位- 以国际单位制表示的数值应视为标准值。括号中给出的值仅供参考。 1.3 分析程序按以下顺序出现: 小节 磷酸中硫酸亚铁还原铀和重铬酸盐滴定法 2. 用点火（重量）杂质校正法测定铀和氧铀原子比 3. 直接燃烧导热法测定碳（总量） 2. 热水解离子选择电极法测定总氯和氟 3. 用库仑、电解水分分析仪法测定水分 8 – 15 凯氏定氮法测定氮 16 – 23 多丝表面电离质谱法测定铀同位素组成 4. 高纯二氧化铀中微量元素的光谱化学测定 5. 用氧化镓载体直流电弧技术光谱化学测定银 5. 铜火花光谱化学法测定稀土 2. 火花源质谱法测定杂质元素 2. 氮吸收法测定的表面积 24 – 30 反应堆级二氧化铀芯块中的总气体 2. 钍和稀土元素的光谱分析 2. 惰性气体熔化氢气 3. 铀同位素质谱分析 2. 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 4.1 二氧化铀被用作核反应堆燃料。为了适用于此目的，材料必须满足铀含量、化学计量比、同位素组成和杂质含量的某些标准。这些测试方法旨在显示给定材料是否符合规范中所述的这些项目的规范 C753 和 C776 . 4.1.1 进行分析以确定材料是否具有干重基础上规定的最低铀含量。 4.1.2 氧化物粉末的化学计量比有助于预测其在球团生产过程中的烧结行为。 4.1.3 测定二氧化铀粉末中铀的同位素含量，以确定有效裂变含量是否符合买方规范。 4.1.4 杂质含量的测定是为了确保不超过某些杂质元素的最大浓度限制。计算等效硼含量（EBC）时也需要测定杂质。 4.1.5 对已完成的芯块进行氧铀比测定，以确定它们是否具有适当的化学计量比，从而在辐照期间实现最佳性能。

1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade uranium dioxide powders and pellets to determine compliance with specifications. 1.2 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.3 The analytical procedures appear in the following order: Sections Uranium by Ferrous Sulfate Reduction in Phosphoric Acid and Dichromate Titration Method 2 Uranium and Oxygen Uranium Atomic Ratio by the Ignition (Gravimetric) Impurity Correction Method 3 Carbon (Total) by Direct Combustion-Thermal Conductivity Method 2 Total Chlorine and Fluorine by Pyrohydrolysis Ion-Selective Electrode Method 3 Moisture by the Coulometric, Electrolytic Moisture Analyzer Method 8 – 15 Nitrogen by the Kjeldahl Method 16 – 23 Isotopic Uranium Composition by Multiple-Filament Surface Ionization Mass Spectrometric Method 4 Spectrochemical Determination of Trace Elements in High-Purity Uranium Dioxide 5 Silver, Spectrochemical Determination of, by Gallium Oxide Carrier D-C Arc Technique 5 Rare Earths by Copper Spark-Spectrochemical Method 2 Impurity Elements by a Spark-Source Mass Spectrographic Method 2 Surface Area by Nitrogen Absorption Method 24 – 30 Total Gas in Reactor-Grade Uranium Dioxide Pellets 2 Thorium and Rare Earth Elements by Spectroscopy 2 Hydrogen by Inert Gas Fusion 3 Uranium Isotopic Analysis by Mass Spectrometry 2 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 4.1 Uranium dioxide is used as a nuclear-reactor fuel. In order to be suitable for this purpose, the material must meet certain criteria for uranium content, stoichiometry, isotopic composition, and impurity content. These test methods are designed to show whether or not a given material meets the specifications for these items as described in Specifications C753 and C776 . 4.1.1 An assay is performed to determine whether the material has the minimum uranium content specified on a dry weight basis. 4.1.2 The stoichiometry of the oxide powder is useful for predicting its sintering behavior in the pellet production process. 4.1.3 Determination of the isotopic content of the uranium in the uranium dioxide powder is made to establish whether the effective fissile content is in compliance with the purchaser's specifications. 4.1.4 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded. Determination of impurities is also required for calculation of the equivalent boron content (EBC). 4.1.5 Determination of the oxygen-to-uranium ratio is performed on the completed pellets to determine whether they have the appropriate stoichiometry for optimal performance during irradiation.