1.1 本试验方法适用于铀钚比大于等于2.5的未辐照铀钚混合氧化物。大量钚（Pu）的存在使铀与钚的比率降低，可能导致铀（U）的分析结果降低 ( 1. ) 2. 如果钚和铀的量足以减缓还原步骤，并防止在规定的时间内完全还原铀。在铀钚比较低的情况下，尤其是在20 正在滴定的铀量为毫克至50毫克，而不是100毫克 参考文献中引用的研究中，mg至300 mg ( 1. ) 在铀钚比小于2.5的情况下使用该试验方法之前，应获得该信息的确认。 1.2 第节所列数据中确定的铀量 12 20岁 然而，如上所述，该试验方法所含的铁超过了在含有300 mg铀且铀钚比大于或等于2的溶液中减少铀和钚总量所需的铁。 5.已分析了铀钚比大于或等于2.5的含300 mg铀的溶液 ( 1. ) 使用第节所述的试剂体积和条件 10 . 1.3 以国际单位制表示的值应视为标准值。本标准不包括其他测量单位。 1.4 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践，并确定监管限制的适用性。 有关具体危险说明，请参阅第节 8. . 1.5 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《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 4.1 决定铀测定方法选择的因素包括可用的样品数量、样品纯度、期望的可靠性水平和设备可用性。 4.2 该测试方法适用于20 mg至300mg的铀，适用于快增殖反应堆（FBR）-铀钚比为2.5或更高的混合氧化物，对大多数通常规定用于FBR混合氧化物燃料的金属杂质元素具有耐受性，且不使用特殊设备。 4.3 研究了滴定法的耐用性 ( 6. ) 和重量 ( 7. ) 用重铬酸钾滴定铀。

1.1 This test method covers unirradiated uranium-plutonium mixed oxide having a uranium to plutonium ratio of 2.5 and greater. The presence of larger amounts of plutonium (Pu) that give lower uranium to plutonium ratios may give low analysis results for uranium (U) ( 1 ) 2 , if the amount of plutonium together with the uranium is sufficient to slow the reduction step and prevent complete reduction of the uranium in the allotted time. Use of this test method for lower uranium to plutonium ratios may be possible, especially when 20 mg to 50 mg quantities of uranium are being titrated rather than the 100 mg to 300 mg in the study cited in Ref ( 1 ) . Confirmation of that information should be obtained before this test method is used for ratios of uranium to plutonium less than 2.5. 1.2 The amount of uranium determined in the data presented in Section 12 was 20 mg to 50 mg. However, this test method, as stated, contains iron in excess of that needed to reduce the combined quantities of uranium and plutonium in a solution containing 300 mg of uranium with uranium to plutonium ratios greater than or equal to 2.5. Solutions containing up to 300 mg uranium with uranium to plutonium ratios greater than or equal to 2.5 have been analyzed ( 1 ) using the reagent volumes and conditions as described in Section 10 . 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 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. For specific hazard statements, see Section 8 . 1.5 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 Factors governing selection of a method for the determination of uranium include available quantity of sample, sample purity, desired level of reliability, and equipment availability. 4.2 This test method is suitable for samples between 20 mg to 300 mg of uranium, is applicable to fast breeder reactor (FBR)-mixed oxides having a uranium to plutonium ratio of 2.5 and greater, is tolerant towards most metallic impurity elements usually specified for FBR-mixed oxide fuel, and uses no special equipment. 4.3 The ruggedness of the titration method has been studied for both the volumetric ( 6 ) and the weight ( 7 ) titration of uranium with dichromate.