1.1 本指南为表征乏核燃料（SNF）的物理和化学性质所涉及的测试类型和范围提供了指导，以支持其在地质处置库中的临时储存、运输和处置。本指南主要适用于商用轻水反应堆（LWR）乏燃料和武器生产的乏燃料，尽管个别测试/分析可能适用于其他乏燃料，例如研究和测试反应堆的乏燃料和混合氧化物（MOX）乏燃料。该测试旨在提供支持地质处置库设计、安全分析和性能评估的信息，以最终处置SNF。 1.2 所述测试包括物理属性的表征，如物理外观、重量、密度、形状/几何形状、SNF覆层损伤的程度和类型。所述测试还包括测量/检查放射性核素含量、微观结构和腐蚀产物含量等化学属性，以及干燥速率、氧化速率（在干燥空气、水蒸气和液态水中）、点火温度和溶解/降解速率等环境响应特征。 对于临时储存、运输或地质处置库处置的SNF性能的任何给定分析，不一定要进行本文所述的所有表征测试，特别是在已经存在大量文献针对特定使用条件下的相关参数的区域。 1.3 在制定本指南中的SNF表征活动时，假设SNF已在反应堆排放和干法运输至储存库之间的某个时间储存在临时储存设施中。SNF可能是湿储存（例如，乏燃料池）或干储存（例如，独立乏燃料储存装置（ISFSI））或两者兼有，临时储存方式可能会影响SNF特性。 1.4 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和健康实践，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 为了证明符合监管要求并支持关闭后存储库，需要有关SNF属性、特征和行为的性能评估信息。SNF的这些属性反过来支持运输、临时存储和存储库关闭前的安全分析，以及存储库关闭后的性能评估。在美国，商用轻水堆SNF的临时干式储存按照《联邦法规》第10篇第72部分进行管理，该部分要求包壳在临时储存期间不得承受足以将燃料从包壳释放到容器环境中的任何“严重”损坏。 在其他国家，适当的管理机构将制定有关商用轻水堆SNF临时干式储存的法规。然而，包壳损坏不足以在临时储存期间释放燃料，可能仍以小裂纹或针孔的形式出现。根据第节给出的定义，这些裂纹/针孔足以将燃料分类为“失效燃料”或“破损燃料” 3. 出于处置库的目的，因为它们可以允许水蒸气或液体与乏燃料基质接触，从而为放射性核素从废物体中释放提供途径。此外，在长期储存条件下，干式或湿式临时储存的燃料棒中的针孔/裂纹也可能发展成更大的缺陷（例如，包层“解扣”现象）。因此，SNF表征应足以根据需要确定两种用途的“失效燃料”量。这可能涉及检查反应堆运行记录、超声波检测、啜吸、分析残余水和乏燃料组件或容器的干燥动力学。 5.2 每个国家的法规可能包含对处置库中乏燃料和高放废物的化学或物理（或两者）特性和长期降解行为的约束和限制。根据这些监管约束，评估废物体（WF）、废物包装（WP）和其他工程屏障系统（EBS）的设计和性能需要了解SNF的化学/物理特性和降解行为，这些可以通过本指南提供的测试和数据评估方法提供，以美国为例，如下所示: 5.2.1 例如，在美国，《联邦法规》第10篇第60部分第135节和第113节要求WF为固体、非颗粒、非自燃和非化学反应性材料，废物包装不含液体、颗粒物，或可燃材料，并且EBS的材料/组件设计为假设预期过程和事件基本上完全控制NRC的高放废物- 指定监管期限。 5.2.2 例如，在美国，《联邦法规》第10篇第63部分第113节要求电子束的设计应确保电子束与自然屏障结合使用时，电子束的性能评估符合《联邦法规》第10篇的年度合理预期个人剂量保护标准，第63部分第311节和《联邦法规》第10篇第63部分第312节合理最大程度暴露的个人标准，并且在永久关闭后的NRC指定监管合规期内，不得超过《联邦法规》第10篇第63部分第331节的EPA地下水保护剂量限值。 5.2.3 例如，在美国，《联邦法规》第10篇第63部分第114（e）、（f）和（g）节以及《联邦法规》第10篇第63部分第115（c）节要求提供技术基础，以包括或排除与电子束屏障相关的降解/改变过程，同样，也为该岗位使用的退化/改造模型提供了技术基础- EBS屏障隔离废物能力的关闭性能评估。 5.3 在地质处置库的关闭前安全分析和关闭后性能评估中，必须考虑腐蚀/损坏的铀金属基SNF的化学反应性增强和退化情况。这方面的一个例子是铀金属基SNF中自燃行为的可能性（见指南） C1454 ). 由于金属铀或铀氢化物（或两者）的易燃性，以及暴露的铀金属的水溶速率增强，必须在储存库或临时储存设施安全分析中考虑化学活性或自燃行为增强的可能性，以及评估储存库关闭后从储存库场址边界释放放射性核素的可能性。 5.4 可能需要对SNF的几个关键属性进行表征，以支持上述两个存储库的设计和性能分析- 地面SNF接收和滞后储存设施、放置SNF的WP和地下永久侵位漂移EBS。 5.4.1 处置库废物包设计必须确保放置在处置库中的废物可以容纳在废物包漂移安置许可条件的放射性核素和热负荷范围内。为此，应确定暴露在氧气/水环境中时的放射性核素含量和氧化速率。 5.4.2 轻水堆乏燃料包壳的状况（特别是关于氢化物含量和形态）可能会影响临时储存、运输和地质处置库中包壳的性能。氢化物含量高的覆层的腐蚀和随后的失效率可能大于氢化物含量低或无氢化物含量的覆层。如果发现性能评估对包层的故障率敏感，则可能需要进行氢化锆含量和取向测试，尤其是对于高燃耗LWR SNF。 5.4.3 金属铀基乏燃料介绍了化学反应性的各个方面，如燃烧性和自燃性（见 C1454 )应在WP设计和性能评估中，以及在处置库安置之前与临时储存和运输相关的安全分析中解决这一问题。金属铀基核燃料已广泛用于核反应堆；有时用于商业反应堆（例如Magnox），但更多用于钚和氚生产反应堆。这些生产反应堆中金属铀SNF的排放方式，和/或未经再处理的那部分乏燃料的临时湿法储存方式，在许多情况下都对SNF组件造成了严重的腐蚀和机械损伤。这种破坏导致金属铀直接暴露在盆地水中。铀与水接触时的相对较高的化学反应性可能会对组件造成重大物理损坏，这是腐蚀产物积聚的结果，并在暴露的燃料表面和燃料基质中产生铀氢化物包裹体，进而进一步增加材料的化学活性。 该乏燃料与空气、水蒸汽或液态水的反应会在设计基准事件中引入重要的热源项。为了支持这些事件的评估，应调查SNF的物理条件（即光学/视觉可观察损伤的程度）、化学氧化动力学、点火特性和放射性核素释放特性。 5.4.4 废物包装/工程屏障系统的热分析需要量化潜在的化学热源。为了确定这一点，应提供送往处置库的废物罐中的活性铀金属量，以便对废物包装/工程屏障系统进行热分析。 5.4.5 需要放射性核素清单和物理/化学特性，以便能够开发储存罐、运输包和WP装载和安置配置。 5.4.6 储存库可湿性粉剂材料的选择和设计必须考虑废物和可湿性粉剂之间的潜在相互作用。必须考虑废物的潜在化学形式，并评估残余水或杂质（或两者）的影响。 5.4.7 当储存条件可能改变了SNF的降解特性（例如，关于高燃耗LWR SNF包层中氢化物含量和形态）时，SNF在交付至储存库之前的临时储存和运输条件的历史非常重要。商用SNF的临时干式储存要求燃料包壳在储存期间不应受到严重损坏，直至燃料从燃料棒释放到碳罐中。在储存期间，在不违反临时储存要求的情况下，包壳中可能会形成小孔或裂纹，但可能会导致燃料被归类为失效燃料，以便于处置库处置。 因此，干燥商用SNF燃料的目的是为了防止临时储存造成的严重损坏。如果运输或临时储存条件导致SNF进一步退化或对储存库关闭前安全或关闭后性能分析重要的特性变化的可能性很大，则表征应提供足够的信息来评估这些变化。

1.1 This guide provides guidance for the types and extent of testing that would be involved in characterizing the physical and chemical nature of spent nuclear fuel (SNF) in support of its interim storage, transport, and disposal in a geologic repository. This guide applies primarily to commercial light water reactor (LWR) spent fuel and spent fuel from weapons production, although the individual tests/analyses may be used as applicable to other spent fuels such as those from research and test reactors and mixed oxide (MOX) spent fuel. The testing is designed to provide information that supports the design, safety analysis, and performance assessment of a geologic repository for the ultimate disposal of the SNF. 1.2 The testing described includes characterization of such physical attributes as physical appearance, weight, density, shape/geometry, degree, and type of SNF cladding damage. The testing described also includes the measurement/examination of such chemical attributes as radionuclide content, microstructure, and corrosion product content, and such environmental response characteristics as drying rates, oxidation rates (in dry air, water vapor, and liquid water), ignition temperature, and dissolution/degradation rates. Not all of the characterization tests described herein must necessarily be performed for any given analysis of SNF performance for interim storage, transportation, or geological repository disposal, particularly in areas where an extensive body of literature already exists for the parameter of interest in the specific service condition. 1.3 It is assumed in formulating the SNF characterization activities in this guide that the SNF has been stored in an interim storage facility at some time between reactor discharge and dry transport to a repository. The SNF may have been stored either wet (for example, a spent fuel pool), or dry (for example, an independent spent fuel storage installation (ISFSI)), or both, and that the manner of interim storage may affect the SNF characteristics. 1.4 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 and health 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 In order to demonstrate conformance to regulatory requirements and support the post-closure repository performance assessment information is required about the attributes, characteristics, and behavior of the SNF. These properties of the SNF in turn support the transport, interim storage, and repository pre-closure safety analyses, and repository post-closure performance assessment. In the United States, the interim dry storage of commercial LWR SNF is regulated per the Code of Federal Regulations, Title 10, Part 72, which requires that the cladding must not sustain during the interim storage period any “gross” damage sufficient to release fuel from the cladding into the container environment. In other countries, the appropriate governing body will set regulations regarding interim dry storage of commercial LWR SNF. However, cladding damage insufficient to allow the release of fuel during the interim storage period may still occur in the form of small cracks or pinholes. These cracks/pinholes could be sufficient to classify the fuel as “ failed fuel” or “breached fuel” per the definitions given in Section 3 for repository disposal purposes, because they could allow contact of water vapor or liquid with the spent fuel matrix and thus provide a pathway for radionuclide release from the waste form. Also, pinholes/cracks in fuel rods in dry or wet interim storage can also develop into much larger defects (for example, the phenomenon of cladding “unzipping”) under long-term repository conditions. Therefore SNF characterization should be adequate to determine the amount of “failed fuel” for either usage as required. This could involve the examination of reactor operating records, ultrasonic testing, sipping, and analysis of the residual water and drying kinetics of the spent fuel assemblies or canisters. 5.2 Regulations in each country may contain constraints and limitations on the chemical or physical (or both) properties and long-term degradation behavior of the spent fuel and HLW in the repository. Evaluating the design and performance of the waste form (WF), waste packaging (WP), and the rest of the engineered barrier system (EBS) with respect to these regulatory constraints requires knowledge of the chemical/physical characteristics and degradation behavior of the SNF that could be provided by the testing and data evaluation methods provided by this guide, using the United States as an example, as follows: 5.2.1 In the United States, for example, Code of Federal Regulations, Title 10, Part 60 Sections 135 and 113 require that the WF be a material that is solid, non-particulate, non-pyrophoric, and non-chemically reactive, that the waste package contain no liquid, particulates, or combustible materials and that the materials/components of the EBS be designed to provide—assuming anticipated processes and events—substantially complete containment of the HLW for the NRC-designated regulatory period. 5.2.2 In the United States, for example, Code of Federal Regulations, Title 10, Part 63 Section 113 requires that the EBS be designed such that, working in combination with the natural barriers, the performance assessment of the EBS demonstrates conformance to the annual reasonably expected individual dose protection standard of Code of Federal Regulations, Title 10, Part 63 Section 311 and the reasonably maximally exposed individual standard of Code of Federal Regulations, Title 10, Part 63 Section 312, and shall not exceed EPA dose limits for protection of groundwater of Code of Federal Regulations, Title 10, Part 63 Section 331 during the NRC-designated regulatory compliance period after permanent closure. 5.2.3 In the United States, for example, Code of Federal Regulations, Title 10, Part 63 Section 114 (e), (f), and (g) and Code of Federal Regulations, Title 10, Part 63 Section 115 (c) require that a technical basis be provided for the inclusion or exclusion of degradation/alteration processes pertinent to the barriers of the EBS, and that likewise a technical basis be provided for the degradation/alteration models used in the post-closure performance assessment of the capability of the EBS barriers to isolate waste. 5.3 The enhanced chemical reactivity and degraded condition of corroded/damaged uranium metal-based SNF must be accounted for in both the pre-closure safety analyses and the post-closure performance assessment of the geologic repository. An example of this would be the potential for pyrophoric behavior in uranium metal-based SNF (see Guide C1454 ). Due to the combustibility of the metallic uranium or uranium hydride (or both), and the enhanced aqueous dissolution rates for the exposed uranium metal, the potential for enhanced chemical activity or pyrophoric behavior must be factored into the repository or interim storage facility safety analyses, and assessments of the potential for radionuclide releases from the repository site boundary after repository closure. 5.4 Characterization of several key properties of SNF may be required to support the design and performance analyses of both repository above-ground SNF receipt and lag storage facilities, the WP into which the SNF is placed, and the subsurface permanent emplacement drift EBS. 5.4.1 Repository waste package design must ensure that the waste to be placed in the repository can be accommodated within the radionuclide and thermal loading ranges of the waste package drift emplacement licensing conditions. To do this the radionuclide content and oxidation rate when exposed to oxygen/water environments should be determined. 5.4.2 The condition of the LWR spent fuel cladding (particularly with respect to hydride content and morphology) could potentially influence the performance of the cladding in interim storage, transportation, and geologic repository disposal. The corrosion and consequent failure rate of cladding with high hydride content may be greater than that of low or no hydride content. If the performance assessment is found to be sensitive to the failure rate of the cladding, it may be necessary to perform zirconium hydride content and orientation testing, particularly for high burnup LWR SNF. 5.4.3 Metallic uranium-based spent fuel introduces aspects of chemical reactivity, such as combustibility and pyrophoricity (see C1454 ), that should be addressed in WP design and performance assessment, and in safety analyses associated with interim storage and transportation prior to repository emplacement. Metallic uranium-based nuclear fuel has been widely used in nuclear reactors; sometimes for commercial reactors (for example, Magnox) but more often in plutonium and tritium production reactors. The manner of discharge of metallic uranium SNF from these production reactors, and/or the manner of temporary wet storage of that portion of the spent fuel that was not reprocessed has in many instances resulted in significant corrosion and mechanical damage to the SNF assemblies. This damage has resulted in the direct exposure of the metallic uranium to the basin water. The relatively high chemical reactivity of uranium in contact with water can result in significant physical damage to the assemblies as the result of corrosion product buildup, and the creation in the exposed fuel surface and fuel matrix of uranium hydride inclusions which in turn further increase the chemical activity of the material. The reaction of this spent fuel with air, water vapor, or liquid water can introduce a significant heat source term into design basis events. In order to support the evaluation of these events, the physical condition (that is, the degree of optically/visually observable damage), the chemical oxidation kinetics, the ignition characteristics, and radionuclide release characteristics of the SNF should be investigated. 5.4.4 The thermal analysis of the waste package/engineered barrier system requires quantification of the potential chemical heat source. To determine this, the amount of reactive uranium metal in the waste canisters sent to the repository should be provided so the thermal analysis of the waste package/engineered barrier system can be performed. 5.4.5 Radionuclide inventories and physical/chemical characteristics are required to enable storage canister, transportation package, and WP loading and emplacement configurations to be developed. 5.4.6 Repository WP materials selection and design must account for the potential interactions between the waste and WP. The potential chemical forms of the wastes must be considered, and the effects of residual water or impurities (or both) should be evaluated. 5.4.7 The history of the SNF interim storage and transportation conditions prior to delivery to the repository is important whenever the storage conditions may have altered the degradation characteristics of the SNF (for example, with respect to hydride content and morphology in high burnup LWR SNF cladding). Interim dry storage of commercial SNF requires that the fuel cladding should not sustain gross damage during the storage period to the extent that fuel is released from the fuel rods into the canister. Small pinholes or cracks may form in the cladding during the storage period without violating this interim storage requirement, but may cause the fuel to be classified as failed fuel for repository disposal purposes. The objective of drying commercial SNF fuel is thus to preclude gross damage for interim storage purposes. If the conditions of transport or interim storage are such that there is a significant potential for further degradation of the SNF or change in properties important to the repository pre-closure safety or post-closure performance analyses, the characterization should provide sufficient information to evaluate these changes.