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    ASTM C781 - 20

    Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components

    Active Standard ASTM C781 | Developed by Subcommittee: D02.F0

    Book of Standards Volume: 05.05

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    Significance and Use

    4.1 Property data obtained with the recommended test methods identified herein may be used for research and development, design, manufacturing control, specifications, performance evaluation, and regulatory statutes pertaining to nuclear reactors that utilize graphite.

    4.2 The referenced test methods are applicable primarily to specimens in the non-irradiated and non-oxidized state. Testing irradiated specimens often requires specimen geometries that do not meet the requirements of the standard. Specific instructions or recommendations with respect to testing non-conforming geometries can be found in STP 15784 and/or Guide D7775. When testing irradiated specimens at elevated temperatures, the effects of annealing should be considered (see Note 1).

    Note 1: Exposure to fast neutron radiation will result in atomic and microstructural changes to graphite. This radiation damage occurs when energetic particles, such as fast neutrons, impinge on the crystal lattice and displace carbon atoms from their equilibrium positions, creating a lattice vacancy and an interstitial carbon atom. The lattice strain that results from displacement damage causes significant structural and property changes in the graphite and is a function of the irradiation temperature and dose. When the temperature of the graphite is brought above the temperature at which it was irradiated, enough energy is provided that the structure of the graphite will anneal back to its original condition. Therefore, measurement techniques that bring the specimen temperature above the irradiation temperature can result in property values that change during the measurement process. For this reason, measurements made on irradiated test specimens below the irradiation temperature will produce results that are representative of the irradiation damage. However, measurements made at temperatures above the irradiation temperature could include the effects of annealing.

    4.3 Additional test methods are in preparation and will be incorporated. The user is cautioned to employ the latest revision.

    1. Scope

    1.1 This practice covers the application and limitations of test methods for measuring the properties of graphite materials. These properties may be used for the design and evaluation of gas-cooled reactor components.

    1.2 The test methods referenced herein are applicable to materials used for replaceable and permanent components as defined in Section 7 and includes fuel elements; removable reflector elements and blocks; permanent side reflector elements and blocks; core support pedestals and elements; control rod, reserve shutdown, and burnable poison compacts; and neutron shield material. Specific aspects with respect to testing of irradiated materials are addressed.

    1.3 This practice includes test methods that have been selected from ASTM standards and guides that are specific to the testing of materials listed in 1.2. Comments on individual test methods for graphite components are given in Section 8. The test methods are summarized in Table 1.

    1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered 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, health, and environmental 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.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    C559 Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite Articles

    C577 Test Method for Permeability of Refractories

    C611 Test Method for Electrical Resistivity of Manufactured Carbon and Graphite Articles at Room Temperature

    C625 Practice for Reporting Irradiation Results on Graphite

    C651 Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Four-Point Loading at Room Temperature

    C695 Test Method for Compressive Strength of Carbon and Graphite

    C747 Test Method for Moduli of Elasticity and Fundamental Frequencies of Carbon and Graphite Materials by Sonic Resonance

    C749 Test Method for Tensile Stress-Strain of Carbon and Graphite

    C769 Test Method for Sonic Velocity in Manufactured Carbon and Graphite Materials for Use in Obtaining an Approximate Value of Youngs Modulus

    C816 Test Method for Sulfur Content in Graphite by Combustion-Iodometric Titration Method

    C838 Test Method for Bulk Density of As-Manufactured Carbon and Graphite Shapes

    C1039 Test Methods for Apparent Porosity, Apparent Specific Gravity, and Bulk Density of Graphite Electrodes

    C1179 Test Method for Oxidation Mass Loss of Manufactured Carbon and Graphite Materials in Air

    C1233 Practice for Determining Equivalent Boron Contents of Nuclear Materials

    C1274 Test Method for Advanced Ceramic Specific Surface Area by Physical Adsorption

    D346 Practice for Collection and Preparation of Coke Samples for Laboratory Analysis

    D1193 Specification for Reagent Water

    D2854 Test Method for Apparent Density of Activated Carbon

    D2862 Test Method for Particle Size Distribution of Granular Activated Carbon

    D3104 Test Method for Softening Point of Pitches (Mettler Softening Point Method)

    D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants

    D4292 Test Method for Determination of Vibrated Bulk Density of Calcined Petroleum Coke

    D5600 Test Method for Trace Metals in Petroleum Coke by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES)

    D7219 Specification for Isotropic and Near-isotropic Nuclear Graphites

    D7542 Test Method for Air Oxidation of Carbon and Graphite in the Kinetic Regime

    D7775 Guide for Measurements on Small Graphite Specimens

    D7779 Test Method for Determination of Fracture Toughness of Graphite at Ambient Temperature

    D7846 Practice for Reporting Uniaxial Strength Data and Estimating Weibull Distribution Parameters for Advanced Graphites

    D7972 Test Method for Flexural Strength of Manufactured Carbon and Graphite Articles Using Three-Point Loading at Room Temperature

    D8186 Test Method for Measurement of Impurities in Graphite by Electrothermal Vaporization Inductively Coupled Plasma Optical Emission Spectrometry (ETV-ICP OES)

    E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves

    E132 Test Method for Poissons Ratio at Room Temperature

    E228 Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer

    E261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques

    E639 Test Method for Measuring Total-Radiance Temperature of Heated Surfaces Using a Radiation Pyrometer

    E1269 Test Method for Determining Specific Heat Capacity by Differential Scanning Calorimetry

    E1461 Test Method for Thermal Diffusivity by the Flash Method

    E2716 Test Method for Determining Specific Heat Capacity by Sinusoidal Modulated Temperature Differential Scanning Calorimetry

    ICS Code

    ICS Number Code 27.120.10 (Reactor engineering)

    UNSPSC Code

    UNSPSC Code 11101507(Graphite)

    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/C0781-20

    Citation Format

    ASTM C781-20, Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components, ASTM International, West Conshohocken, PA, 2020, www.astm.org

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