1.1 本试验方法适用于测定核级燃料材料中铀（U）的同位素组成。使用四极感应耦合等离子体质谱仪（Q-ICP-MS）测定以下同位素重量百分比: 233 U 234 U 235 U 236 U、 和 238 U、 在酸溶解和样品稀释到水中或稀释硝酸（HNO）后，可以对各种材料基质进行分析 3. )酸性。这些材料包括:燃料产品、氧化铀、氧化铀合金、硝酸铀酰（UNH）晶体和溶液。本试验方法中讨论的样品制备侧重于燃料产品材料，但可用于氧化铀或氧化铀合金。可以使用其他制备技术，并提供了一些参考。本试验方法不需要通过阴离子交换萃取净化铀，因为其他试验方法，如放射化学和热电离质谱（TIMS）也需要净化铀。 ASTM STP 1344中也描述了该试验方法 2. . 1.2 这个 233 铀同位素主要是通过比较 233 由于材料中通常不存在U峰值强度，因此U峰值强度为背景点。本试验方法中提供的示例数据不包含任何 233 U数据。A. 233 U富集标准见第节 8. ，并可作为所列其他标准材料的定量加标剂。 1.3 使用单一标准校准技术。最佳精度（或低偏差）是通过使用与样品富集度密切匹配的单一标准来实现的。强度或浓度也被调整到一定的公差范围内，以提供低丰度同位素的良好统计计数精度，同时保持高丰度同位素的低偏差，这是由于高强度死时间效应造成的。 没有使用空白减法或背景校正。根据选择的标准，富集度在耗尽和97之间 % 可以量化。校准和测量是通过测量每个低丰度同位素的强度比与 233 U 234 U 235 U 236 U、 和 238 U、 通过差分获得高丰度同位素。 1.4 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。校准仪器，并以同位素重量百分比（Wt）为单位测量样品 %). 例如 235 铀富集可以表示为Wt % 235 U或作为g 235 U/100g铀。假设溶液密度为1.0，给出了关于稀释的陈述，特别是μg/g浓度或更低的稀释，因为在进行同位素比值测量时，溶液的铀浓度并不重要，除非在公差范围内保持合理一致的强度。 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。 第节给出了具体的预防说明 9 . 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 核级反应堆燃料材料必须符合某些标准，如规范中所述 C753 , C776 , C778 和 C833 . 这些标准包括铀同位素组成。该试验方法旨在证明给定材料是否符合同位素要求，以及有效裂变含量是否符合买方规范。

1.1 This test method is applicable to the determination of the isotopic composition of uranium (U) in nuclear-grade fuel material. The following isotopic weight percentages are determined using a quadrupole inductively coupled plasma-mass spectrometer (Q-ICP-MS): 233 U, 234 U, 235 U, 236 U, and 238 U. The analysis can be performed on various material matrices after acid dissolution and sample dilution into water or dilute nitric (HNO 3 ) acid. These materials include: fuel product, uranium oxide, uranium oxide alloys, uranyl nitrate (UNH) crystals, and solutions. The sample preparation discussed in this test method focuses on fuel product material but may be used for uranium oxide or a uranium oxide alloy. Other preparation techniques may be used and some references are given. Purification of the uranium by anion-exchange extraction is not required for this test method, as it is required by other test methods such as radiochemistry and thermal ionization mass spectroscopy (TIMS). This test method is also described in ASTM STP 1344 2 . 1.2 The 233 U isotope is primarily measured as a qualitative measure of its presence by comparing the 233 U peak intensity to a background point since it is not normally found present in materials. The example data presented in this test method do not contain any 233 U data. A 233 U enriched standard is given in Section 8 , and it may be used as a quantitative spike addition to the other standard materials listed. 1.3 A single standard calibration technique is used. Optimal accuracy (or a low bias) is achieved through the use of a single standard that is closely matched to the enrichment of the samples. The intensity or concentration is also adjusted to within a certain tolerance range to provide good statistical counting precision for the low-abundance isotopes while maintaining a low bias for the high-abundance isotopes, resulting from high-intensity dead time effects. No blank subtraction or background correction is utilized. Depending upon the standards chosen, enrichments between depleted and 97 % can be quantified. The calibration and measurements are made by measuring the intensity ratios of each low-abundance isotope to the intensity sum of 233 U, 234 U, 235 U, 236 U, and 238 U. The high-abundance isotope is obtained by difference. 1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. The instrument is calibrated and the samples measured in units of isotopic weight percent (Wt %). For example, the 235 U enrichment may be stated as Wt % 235 U or as g 235 U/100 g of U. Statements regarding dilutions, particularly for μg/g concentrations or lower, are given assuming a solution density of 1.0 since the uranium concentration of a solution is not important when making isotopic ratio measurements other than to maintain a reasonably consistent intensity within a tolerance range. 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. Specific precautionary statements are given in Section 9 . 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 Nuclear-grade reactor fuel material must meet certain criteria, such as those described in Specifications C753 , C776 , C778 , and C833 . Included in these criteria is the uranium isotopic composition. This test method is designed to demonstrate whether or not a given material meets an isotopic requirement and whether the effective fissile content is in compliance with the purchaser's specifications.