1.1 本试验方法涵盖了发射伽马射线的特殊核材料（SNM）的透射校正无损检测（NDA），最常见的是 235 U 239 Pu，和 241 Am，在低密度废料或废物中，包装在圆柱形容器中。该方法也适用于包括裂变产物在内的其他γ发射核素的无损检测。高分辨率伽马射线光谱学用于检测和测量相关核素，并测量和校正容器一系列水平段（准直伽马探测器视图）中的伽马射线衰减。还对信号处理限制引起的计数损失进行了修正 ( 1- 3. ) . 2. 1.2 目前有几个系统正在使用或开发中，用于确定放射性同位素材料NDA的衰减校正 ( 4- 8. ) . 本试验方法中不包括相关技术，断层伽马射线扫描（TGS） ( 9 , 10 , 11 ) . 1.2.1 该测试方法将涵盖分段伽马扫描（SGS）程序的两种实现:( 1. )同位素特定（质量）校准是原始SGS程序，使用已知放射性核素质量的标准来确定质量与校正计数率校准中的探测器响应，该校准仅适用于其校准的特定放射性核素，以及( 2. )效率曲线校准是一种替代方法，通常使用非SNM放射性核素源来确定系统检测效率与伽马能量的关系，从而校准所有感兴趣的伽马发射放射性核素 ( 12 ) . 1.2.1.1 在定义效率的能量范围内，效率曲线校准具有为许多伽马射线提供校准的优点- 有半衰期和伽马发射强度数据的发射核素。 1.3 该分析技术可适用于在208-L[55 gal]桶中装载高达数百克的核素，根据具体的包装和计数设备考虑，适用的范围更为有限。 1.4 测量的传输值必须可用于在分析能量下计算特定于段的衰减校正。 1.5 本标准不包括基于项目内容和密度计算校正系数的相关方法SGS。 1.6 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。 将两个系统的值合并可能会导致不符合标准。 1.7 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 10 . 1.8 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 分段γ射线扫描提供了一种非破坏性方法，用于测量废料和废物中的核素含量，其中基质的具体性质、化学形式以及核素和基质之间的关系可能未知。 5.2 该程序可作为诊断工具，提供项目内传输和核素浓度的垂直剖面。 5.3 物料准备通常仅限于良好的废物/废料分离实践，这些实践产生了任何成功的废物/库存管理和化验方案所需的相对同质的物料，无论使用何种测量方法。此外，在可行的情况下，应将工艺知识作为废物管理计划的一部分，以补充有关物品参数、容器特性和校准系数适当性的信息。 5.4 为了获得最低的检测水平，应使用双通道分析。双通道分析还减少了与透射峰和分析峰之间潜在干扰相关的问题。对于活性较高的项目，可以使用单次通过测定来增加吞吐量。

1.1 This test method covers the transmission-corrected nondestructive assay (NDA) of gamma-ray emitting special nuclear materials (SNMs), most commonly 235 U, 239 Pu, and 241 Am, in low-density scrap or waste, packaged in cylindrical containers. The method can also be applied to NDA of other gamma-emitting nuclides including fission products. High-resolution gamma-ray spectroscopy is used to detect and measure the nuclides of interest and to measure and correct for gamma-ray attenuation in a series of horizontal segments (collimated gamma detector views) of the container. Corrections are also made for counting losses occasioned by signal processing limitations ( 1- 3 ) . 2 1.2 There are currently several systems in use or under development for determining the attenuation corrections for NDA of radioisotopic materials ( 4- 8 ) . A related technique, tomographic gamma-ray scanning (TGS), is not included in this test method ( 9 , 10 , 11 ) . 1.2.1 This test method will cover two implementations of the Segmented Gamma Scanning (SGS) procedure: ( 1 ) Isotope Specific (Mass) Calibration, the original SGS procedure, uses standards of known radionuclide masses to determine detector response in a mass versus corrected count rate calibration that applies only to those specific radionuclides for which it is calibrated, and ( 2 ) Efficiency Curve Calibration, an alternative method, typically uses non-SNM radionuclide sources to determine system detection efficiency vs. gamma energy and thereby calibrate for all gamma-emitting radionuclides of interest ( 12 ) . 1.2.1.1 Efficiency Curve Calibration, over the energy range for which the efficiency is defined, has the advantage of providing calibration for many gamma-emitting nuclides for which half-life and gamma emission intensity data are available. 1.3 The assay technique may be applicable to loadings up to several hundred grams of nuclide in a 208-L [55-gal] drum, with more restricted ranges to be applicable depending on specific packaging and counting equipment considerations. 1.4 Measured transmission values must be available for use in calculation of segment-specific attenuation corrections at the energies of analysis. 1.5 A related method, SGS with calculated correction factors based on item content and density, is not included in this standard. 1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.7 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 10 . 1.8 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 Segmented gamma-ray scanning provides a nondestructive means of measuring the nuclide content of scrap and waste where the specific nature of the matrix and the chemical form and relationship between the nuclide and matrix may be unknown. 5.2 The procedure can serve as a diagnostic tool that provides a vertical profile of transmission and nuclide concentration within the item. 5.3 Item preparation is generally limited to good waste/scrap segregation practices that produce relatively homogeneous items that are required for any successful waste/inventory management and assay scheme, regardless of the measurement method used. Also, process knowledge should be used, when available, as part of a waste management program to complement information on item parameters, container properties, and the appropriateness of calibration factors. 5.4 To obtain the lowest detection levels, a two-pass assay should be used. The two-pass assay also reduces problems related to potential interferences between transmission peaks and assay peaks. For items with higher activities, a single-pass assay may be used to increase throughput.