1.1 本指南涵盖了在恒定压力和温度下用熔盐浸渍石墨的程序。如果用户希望制备石墨试样进行测试，以代表在熔盐核反应堆中暴露在熔盐环境中的材料，则此类程序是必要的。用户需要确保浸渍温度和压力条件反映与熔盐环境有关的条件，注意材料的特性在受到辐照后会发生变化。 注1: 术语浸渍在本指南中使用，因为这是描述过程的正确术语。用户在其他文本中可能会遇到渗透和侵入等其他术语，侵入一词通常用于描述熔盐反应器环境中石墨中开口孔隙的渗透。 1.2 以国际单位制表示的数值应视为标准值。本指南中不包括其他测量单位。 1.3 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。 1.4 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 熔盐反应堆是一种以石墨为反射器和结构材料，氟化物熔盐为冷却剂的核反应堆。在反应堆寿命期间，石墨组分将浸入熔盐中。石墨的多孔结构可能导致熔盐渗透，从而影响石墨的热性能和机械性能。因此，评估熔盐浸渍对制造石墨材料性能的影响很重要。 5.2 本指南的目的是报告在暴露于熔盐环境后制备具有代表性的石墨试样时应考虑的事项。熔盐渗入石墨的程度取决于许多因素，包括石墨的类型、孔隙率的类型和程度、熔盐的性质、浸渍压力和温度以及石墨暴露于熔盐的时间。 5.3 本指南的用户需要根据设计师提供的参数选择足以代表熔盐反应器中的浸渍参数。或者，用户可以选择一组标准的浸渍条件，以允许在一系列石墨中进行比较。 5.4 本指南不具有规定性。描述了典型装置和相关程序。He等人指出了该程序对石墨类型和浸渍条件的敏感性。 5. 5.5 浸渍过程中必须解决四个主要的实际问题: 5.5.1 熔盐的密度大于石墨的密度。在浸渍过程中，需要一种专门设计的工具将石墨样品浸入熔盐中。 5.5.2 一些熔盐（例如FLiBe）有毒，因此有必要通过在手套箱中执行程序来提供防护。 5.5.3 石墨必须远离空气，以避免在高温下氧化。这可以通过在具有受控气氛的手套箱内执行浸渍过程来实现。 5.5.4 熔盐的压力控制可能很难实现。需要一个专门设计的高压釜来容纳试样和熔盐。 5.6 为了评估石墨中熔盐的数量，参数 D 用作测量机械和热材料性能的变量。参数 D o 是盐体积与开孔体积之比。参数 D t 是盐体积与总孔隙体积的比率。 饱和值 D o 当熔盐浸渍在高压下进行时，可以大于1。据推测，石墨的内部微观结构已被高浸渍压力破坏，一些封闭的孔隙已被打开。在这种情况下，参数 D t 更适合表示浸渍过程。

1.1 This guide covers procedures for the impregnation of graphite with molten salt under a consistent pressure and temperature. Such procedures are necessary if the user wishes to prepare graphite specimens for testing that represent material that has been exposed to a molten salt environment in a molten salt nuclear reactor. The user will need to ensure that impregnation temperature and pressure conditions reflect those pertaining to the molten salt environment, noting that the properties of the material will change once it becomes irradiated. Note 1: The term impregnation is used throughout this guide as this is the correct term for the described process. Other terms such as infiltration and intrusion may be encountered by the user in other texts and the term intrusion is commonly used to describe penetration of open porosity in graphite in a molten salt reactor environment. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this guide. 1.3 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. 1.4 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 The molten salt reactor is a nuclear reactor which uses graphite as reflector and structural material and fluoride molten salt as coolant. The graphite components will be submerged in the molten salt during the lifetime of the reactor. The porous structure of graphite may lead to molten salt permeation, which can affect the thermal and mechanical properties of graphite. Consequently, it is important to assess the effect of impregnation of molten salt on the properties of the as-manufactured graphite material. 5.2 The purpose of this guide is to report considerations that should be included in the preparation of graphite specimens representative of that after exposure to a molten salt environment. The degree to which the molten salt will infiltrate the graphite will depend upon a number of factors, including the type of graphite and the type and extent of porosity, the properties of the molten salt, the impregnation pressure and temperature, and the duration of the exposure of the graphite to the molten salt. 5.3 The user of this guide will need to select impregnation parameters sufficiently representative of those in a molten salt reactor based on parameters provided by the designer. Alternatively, the user may select a standard set of impregnation conditions to allow comparisons across a range of graphites. 5.4 This guide is not intended to be prescriptive. A typical apparatus and associated procedure are described. Some indication of the sensitivity of the procedure to graphite type and impregnation conditions is given in He, et al. 5 5.5 There are four major practical issues that must be addressed during the impregnation process: 5.5.1 The density of molten salt is greater than that of graphite. A specially designed tool is required to submerge graphite samples in the molten salt during the impregnation process. 5.5.2 Some molten salts (for example, FLiBe) are poisonous and it is therefore necessary to provide containment by performing procedures within a glove box. 5.5.3 The graphite must be kept away from air to avoid oxidation at high temperature. This can be achieved by performing the impregnation process within a glove box with a controlled atmosphere. 5.5.4 Pressure control of the molten salt can be difficult to achieve. A specially designed autoclave is needed to hold the specimen and molten salt. 5.6 In order to assess the quantity of molten salt in the graphite, parameter D is used as a variable in measuring the mechanical and thermal material properties. Parameter D o is the ratio of salt volume to open pore volume. Parameter D t is the ratio of salt volume to total pore volume. The saturated value of D o can be greater than 1 when the molten salt impregnation takes place at high pressure. It is postulated that the internal microstructure of graphite has been damaged by the high impregnation pressure and some closed pores have been opened. In this case, the parameter D t is more appropriate to represent the impregnation process.