ASTM D7301-21

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Designation: D7301 − 11 (Reapproved 2015) D7301 − 21
Standard Specification for
Nuclear Graphite Suitable for Components Subjected to
Low Neutron Irradiation Dose
This standard is issued under the fixed designation D7301; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Scope*
1.1 This specification covers the classification, processing, and properties of nuclear grade graphite billets with dimensions
sufficient to meet the designer’s requirements for reflector blocks and core support structures, in a high temperature gas cooled
reactor. The graphite classes specified here would be suitable for reactor core applications where neutron irradiation induced
dimensional changes are not a significant design consideration.
1.2 The purpose of this specification is to document the minimum acceptable properties and levels of quality assurance and
traceability for nuclear grade graphite suitable for components subjected to low irradiation dose. Nuclear graphites meeting the
requirements of Specification D7219 are also suitable for components subjected to low neutron irradiation dose.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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.
2. Referenced Documents
2.1 ASTM Standards:
C559C561 Test Method for Bulk Density by Physical Measurements of Manufactured Carbon and Graphite ArticlesAsh in a
Graphite Sample
C709 Terminology Relating to Manufactured Carbon and Graphite (Withdrawn 2017)
C781 Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components
C838 Test Method for Bulk Density of As-Manufactured Carbon and Graphite Shapes
C1233 Practice for Determining Equivalent Boron Contents of Nuclear Materials
D346 Practice for Collection and Preparation of Coke Samples for Laboratory Analysis
D2638 Test Method for Real Density of Calcined Petroleum Coke by Helium Pycnometer
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D7219 Specification for Isotropic and Near-isotropic Nuclear Graphites
D8186 Test Method for Measurement of Impurities in Graphite by Electrothermal Vaporization Inductively Coupled Plasma
Optical Emission Spectrometry (ETV-ICP OES)
This specification is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved June 1, 2015Nov. 1, 2021. Published July 2015November 2021. Originally approved in 2008. Last previous edition approved in 20112015 as
D7301 – 11.D7301 – 11 (2015). DOI: 10.1520/D7301-11R15.10.1520/D7301-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7301 − 21
IEEE/ASTM SI 10 American National Standard for Use of the International System of Units (SI): The Modern Metric System
2.2 ASME Standards:
NQA-1 Quality Assurance Program Requirements for Nuclear Facilities
3. Terminology
3.1 Definitions—Definitions relating to this specification are given in Terminology C709D4175. See Table 1.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 anistropic nuclear graphite, n—graphite in which the isotropy ratio based on the coefficient of thermal expansion is greater
than 1.15.
3.2.2 baking/re-baking charge, n—number of billets in a baking/re-baking furnace run.
3.2.3 bulk density, n—mass of a unit volume of material including both permeable and impermeable voids.
3.2.4 extrusion forming lot, n—number of billets of the same size extruded in an uninterrupted sequence.
3.2.5 green batch, n—mass of coke, recycle green mix, recycle graphite, and pitch that is required to produce a forming lot.
3.2.6 green mix, n—percentage of mix formulation, pitch and additives required for the forming lot, which is processed and ready
to be formed.
3.2.7 graphite billet, n—extruded, molded, or iso-molded graphite artifact with dimensions sufficient to meet the designer’s
requirements for reactor components.
3.2.8 graphite grade, n—designation given to a material by a manufacturer such that it is always reproduced to the same
specification and from the same raw materials and mix formulation.
3.2.9 graphitizing furnace run, n—total number of billets graphitized together in one graphitization furnace.
3.2.10 graphitization charge, n—total number of billets graphitized together in one graphitization furnace.
3.2.11 high purity nuclear graphite, n—nuclear graphite with an Equivalent Boron Content less than 2 ppm.
TABLE 1 ASTM Graphite Grain Size Definitions from Terminology
C709D4175
Graphite Definition of Grains in
A
Designation the Starting Mix that are:
Coarse Grained Generally > 4 mm
Medium-Coarse Grained 2 mm < grain size < 4 mm
B
Medium Grained Generally < 4 mm
Medium Grained 1 mm < grain size < 2 mm
Medium-Fine Grained 100 μm < grain size < 1 mm
Fine Grained Generally < 100 μm
Fine Grained 50 μm < grain size < 100 μm
Superfine Grained Generally < 50 μm
Superfine Grained 10 μm < grain size < 50 μm
Ultrafine Grained Generally < 10 μm
Ultrafine Grained 2 μm < grain size < 10 μm
Microfine Grained Generally < 2 μm
A
Grain size as defined in Terminology C709D4175.
B
For Nuclear graphite, the maximum grain size is 1.68 mm in accordance with
4.2.1.6.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, ThreeTwo Park Ave., New York, NY 10016-5990,
http://www.asme.org.
D7301 − 21
3.2.12 impregnation charge, n—number of billets in an autoclave cycle.
3.2.13 isotropic, adj—in carbon and graphite technology, having an isotropy ratio of 0.9 to 1.1 for a specific property of interest.
3.2.14 isotropic nuclear graphite, n—graphite in which the isotropy ratio based on the coefficient of thermal expansion (25 °C to
500 °C) is 1.00 – 1.10.
3.2.15 isotropy ratio, n—in carbon and graphite technology, ratio of a given property value in the against grain direction to its
corresponding value in the with grain direction (for example, the ratio of coefficients of thermal expansion).
3.2.16 low purity nuclear graphite, n—nuclear graphite with an Equivalent Boron Content greater than 2 ppm but less than
10 ppm.
3.2.17 mix formulation, n—percentages of each specifically sized filler used to manufacture a graphite grade.
3.2.18 molding forming lot, n—number of billets molded from a molding powder lot.
3.2.19 molding powder lot, n—sufficient quantity of re-milled and blended green batch produced from an uninterrupted flow of
raw materials, or produced in a sequence of identical materials batches, to produce a molding forming lot.
3.2.20 nuclear graphite class, n—designation of a nuclear graphite based upon its forming method, isotropy, purity and density
(see Table 2).
3.2.21 production lot, n—specified number of billets made in accordance with this specification and additional requirements
determined by the purchaser.
3.2.22 purification charge, n—number of billets in a purification run.
3.2.23 recycle green mix, n—ground non-baked billets or non-used green mix manufactured in compliance with the mix
formulation specified here.
4. Materials and Manufacture
4.1 Nuclear Graphite Classes—See Table 2.
4.2 Raw Materials:
4.2.1 Fillers:
4.2.1.1 The filler shall consist of a coke derived from a petroleum oil or coal tar.
TABLE 2 ASTM Standard Classes of Nuclear Graphite
Purity
A B CB DC
Class CTE Isotropy Ratio Ash Content, Boron Equivalent, Density, Class
(α /α ) ppm (max) ppm (max)
AG AG g/cm (min) Designation
Isomolded, anisotropic-HP >1.15 300 2 1.7 IAHP
Isomolded, anisotropic-LP >1.15 1000 10 1.7 IALP
Extruded, anisotropic-HP >1.15 300 2 1.7 EAHP
Extruded, anisotropic-LP >1.15 1000 10 1.7 EALP
Molded, anisotropic-HP >1.15 300 2 1.7 MAHP
Molded, anisotropic-LP >1.15 1000 10 1.7 MALP
A
These classes may be further modified by the grain size as defined in Terminology C709D4175.
B
Determined in accordance with Practice Test Method C781C561.
C
Determined in accordance with Test Method C559.
C
Determined in accordance with Practice C1233.
D7301 − 21
4.2.1.2 The coke shall have a coefficient of linear thermal expansion (CTE), determined in accordance with Practice C781 and
-6 -1
measured over the temperature range 25 °C to 500 °C, less than 5.5 × 10 °C °C .
4.2.1.3 The coke shall be sampled and distributed as described in Table 3.
4.2.1.4 Graphite manufactured in compliance with this specification but failing to meet the property requirements of Sections 5
– 7 may be used as recycle material in the mix formulation.
4.2.1.5 Recycle green mix manufactured from raw materials in compliance with this specification may be used in the mix
formulation.
4.2.1.6 The maximum filler particle size used in the mix formulation shall be 1.68 mm.
4.3 Binder—The binder shall consist of coal tar pitch of the same grade from the same manufacturer. The specific binder(s) used
shall be identified to the purchaser and be traceable through the forming lot.
4.4 Impregnant—The impregnant shall consist of a petroleum or coal tar pitch of the same grade from the same manufacturer. The
specific impregnant(s) used shall be identified to the purchaser and be traceable through the impregnation steps.
4.5 Manufacturing or Processing Additives—Additives (for example, extrusion aids) may be used to improve the processing,
quality and properties of the product, but only with the consent and approval of the purchaser, and they must be traceable through
the forming lot.
4.6 Manufacture:
4.6.1 Formulation—The mix formulation (as defined in 3.2.143.2.17) and recycle green mix fraction (as defined in 3.2.203.2.23)
in the filler shall be recorded. This information shall be reported to the purchaser if requested.
4.6.2 Forming—The green mix may be formed by extrusion, molding (including vibrationally molding), or iso-molding.
4.6.3 Graphitization Temperature—The graphitization temperature shall be determined on each billet using the procedure
described in Practice C781. Each billet tested in accordance with Practice C781 shall have a Specific Electrical Resistivity (SER)
corresponding to a graphiti
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