1.1 该方法适用于测定水解核级六氟化铀的同位素组成。它涵盖了 235 U介于0.1和5.0之间 % 质量分数，丰度 234 U介于0.0055和0.05之间 % 质量分数和丰度 236 U介于0.0003和0.5之间 % 质量分数。只要有相应的标准，本试验方法可适用于其他同位素丰度。 1.2 本试验方法适用于硝酸铀酰溶液。 这可以通过在沉积到灯丝上之前将硝酸铀酰溶液转化为氟化铀酰溶液或直接将硝酸铀酰溶液沉积到灯丝上来实现。在后一种情况下，必须使用硝酸铀酰标准进行校准。 1.3 通过向氟化铀或硝酸铀酰溶液提供化学转化，该试验方法也适用于其他核级基质（例如铀氧化物）。 1.4 单位- 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 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====== 5.1 用于生产核燃料的六氟化铀必须符合规范中所述的某些同位素组成标准 C787 和 C996 .

1.1 This method applies to the determination of isotopic composition in hydrolyzed nuclear grade uranium hexafluoride. It covers isotopic abundance of 235 U between 0.1 and 5.0 % mass fraction, abundance of 234 U between 0.0055 and 0.05 % mass fraction, and abundance of 236 U between 0.0003 and 0.5 % mass fraction. This test method may be applicable to other isotopic abundance providing that corresponding standards are available. 1.2 This test method can apply to uranyl nitrate solutions. This can be achieved either by transforming the uranyl nitrate solution to a uranyl fluoride solution prior to the deposition on the filaments or directly by depositing the uranyl nitrate solution on the filaments. In the latter case, a calibration with uranyl nitrate standards must be performed. 1.3 This test method can also apply to other nuclear grade matrices (for example, uranium oxides) by providing a chemical transformation to uranyl fluoride or uranyl nitrate solution. 1.4 Units— The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 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 ====== 5.1 Uranium hexafluoride used to produce nuclear fuel must meet certain criteria for its isotopic composition as described in Specifications C787 and C996 .