1.1 本试验方法描述了使用被动热中子符合计数对废料或废物进行钚含量的无损检测。该试验方法可快速得出结果，并可应用于容量高达数千升的容器中的各种仔细分拣的材料。本试验方法适用于以下各项的测量: 238 聚氨基甲酸酯， 240 Pu，和 242 钚和钚已用于分析总钚含量在10 mg至6 kg之间的项目 ( 1. ) . 2. 1.2 本试验方法需要了解钚同位素的相对丰度，以确定钚的总质量（试验方法 C1030 ). 1.3 本试验方法可能不适用于含有其他自发裂变核素的废料或废物的测定。 1.3.1 对于包含大量含氢材料的容器的测量，该测试方法可能会给出有偏差的结果。 1.3.2 本试验方法中描述的技术已应用于废料和废物以外的材料 ( 2. , 3. ) . 1.4 该测试方法假设使用基于移位寄存器的符合技术 ( 4. ) . 1.5 存在与被动中子符合计数相关的其他几种技术。这些包括中子多重性计数( 5. , 6. ，试验方法 C1500 )，用于矩阵校正的附加源分析 ( 7. ) ，通量探针也用于矩阵补偿，宇宙线抑制 ( 8. ) 提高接近检测极限的精度，以及替代数据采集电子设备，如列表模式数据采集。被动中子符合计数也可以与某些主动询问方案相结合，如在测试方法中 C1316 和 C1493 . 该方法不包括对这些已建立技术的讨论。 1.6 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。 1.7 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 本试验方法适用于测定容器中废料和废物的钚含量，从体积约为1毫升的小罐子到体积为数千升的板条箱和箱子。通常应用于208升（55加仑）桶。总钚含量范围为10 mg至6 kg ( 1. ) . 上限可能会受到限制，具体取决于特定矩阵、校准材料、临界安全或计数设备考虑因素。 5.2 本测试方法适用于美国能源部发货人/接收人确认测量 ( 9 ) 、核材料转移检测和国际原子能机构属性测量 ( 10 ) . 5.3 本试验方法应与废料和废物管理计划结合使用，该计划根据以下部分或全部标准将废料和废物分析项目分为材料类别:体积密度、钚和基质的化学形式、镅与钚同位素比和氢含量。就容器的大小、形状和组成而言，每种类别的包装都应该是统一的。每种材料类别可能需要校准标准，并且可能具有不同的聚氨酯质量限制。 5.4 被动中子符合测量中的偏差与项目大小和密度、基质的均匀性和成分以及核材料的数量和分布有关。 测量结果的精度与核材料的数量、（α，n）反应速率和测量的计数时间有关。 5.4.1 对于良性基质和基质特定测量，该方法假设校准标准物质与待测量项目相匹配，包括基质的均匀性和成分、中子慢化剂和吸收体含量以及核材料的数量，以影响测量。 5.4.2 含有废料和废物的较小容器的测量通常比较大物品的测量更准确。 5.4.3 建议在可行的情况下，对含量均匀的物品进行测量。 核材料、中子慢化剂和中子吸收剂分布的不均匀性有可能导致有偏差的结果。 5.5 通过本试验方法测量的一致中子产额与钚偶数同位素的质量有关。如果这些同位素的相对丰度不准确，则会导致总钚测定值出现偏差。 5.6 典型计数时间在300到3600秒之间。 5.7 应用该方法的可靠结果需要对测量前包装废料和废物的人员以及进行测量的人员进行培训。培训指南可从ANSI 15获得。 20，导轨 C986 , C1009 , C1068 和 C1490 .

1.1 This test method describes the nondestructive assay of scrap or waste for plutonium content using passive thermal-neutron coincidence counting. This test method provides rapid results and can be applied to a variety of carefully sorted materials in containers as large as several thousand liters in volume. The test method applies to measurements of 238 Pu, 240 Pu, and 242 Pu and has been used to assay items whose total plutonium content ranges from 10 mg to 6 kg ( 1 ) . 2 1.2 This test method requires knowledge of the relative abundances of the Pu isotopes to determine the total Pu mass (Test Method C1030 ). 1.3 This test method may not be applicable to the assay of scrap or waste containing other spontaneously fissioning nuclides. 1.3.1 This test method may give biased results for measurements of containers that include large amounts of hydrogenous materials. 1.3.2 The techniques described in this test method have been applied to materials other than scrap and waste ( 2 , 3 ) . 1.4 This test method assumes the use of shift-register-based coincidence technology ( 4 ) . 1.5 Several other techniques that are often encountered in association with passive neutron coincidence counting exist. These include neutron multiplicity counting ( 5 , 6 , Test Method C1500 ), add-a-source analysis for matrix correction ( 7 ) , flux probes also for matrix compensation, cosmic-ray rejection ( 8 ) to improve precision close to the detection limit, and alternative data collection electronics such as list mode data acquisition. Passive neutron coincidence counting may also be combined with certain active interrogation schemes as in Test Methods C1316 and C1493 . Discussions of these established techniques are not included in this method. 1.6 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. 1.7 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 This test method is useful for determining the plutonium content of scrap and waste in containers ranging from small cans with volumes of the order of a mL to crates and boxes of several thousand liters in volume. A common application would be to 208-L (55-gal) drums. Total Pu content ranges from 10 mg to 6 kg ( 1 ) . The upper limit may be restricted depending on specific matrix, calibration material, criticality safety, or counting equipment considerations. 5.2 This test method is applicable for U.S. Department of Energy shipper/receiver confirmatory measurements ( 9 ) , nuclear material diversion detection, and International Atomic Energy Agency attributes measurements ( 10 ) . 5.3 This test method should be used in conjunction with a scrap and waste management plan that segregates scrap and waste assay items into material categories according to some or all of the following criteria: bulk density, the chemical forms of the plutonium and the matrix, americium to plutonium isotopic ratio, and hydrogen content. Packaging for each category should be uniform with respect to size, shape, and composition of the container. Each material category might require calibration standards and may have different Pu mass limits. 5.4 Bias in passive neutron coincidence measurements is related to item size and density, the homogeneity and composition of the matrix, and the quantity and distribution of the nuclear material. The precision of the measurement results is related to the quantity of nuclear material, the (α,n) reaction rate, and the count time of the measurement. 5.4.1 For both benign matrix and matrix specific measurements, the method assumes the calibration reference materials match the items to be measured with respect to the homogeneity and composition of the matrix, the neutron moderator and absorber content, and the quantity of nuclear material, to the extent they affect the measurement. 5.4.2 Measurements of smaller containers containing scrap and waste are generally more accurate than measurements of larger items. 5.4.3 It is recommended that where feasible measurements be made on items with homogeneous contents. Heterogeneity in the distribution of nuclear material, neutron moderators, and neutron absorbers have the potential to cause biased results. 5.5 The coincident neutron production rates measured by this test method are related to the mass of the even number isotopes of plutonium. If the relative abundances of these isotopes are not accurately known, biases in the total Pu assay value will result. 5.6 Typical count times are in the range of 300 to 3600 s. 5.7 Reliable results from the application of this method require training of the personnel who package the scrap and waste prior to measurement and of personnel who perform the measurements. Training guidance is available from ANSI 15.20, Guides C986 , C1009 , C1068 , and C1490 .