ASTM D7219-05
(Specification)Standard Specification for Isotropic and Near-isotropic Nuclear Graphites
Standard Specification for Isotropic and Near-isotropic Nuclear Graphites
SCOPE
1.1 This specification covers the classification, processing, and properties of nuclear grade graphite billets with dimensions sufficient to meet the designers requirements for fuel elements, moderator or reflector blocks, 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 a significant design consideration.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation: D 7219 – 05
Standard Specification for
Isotropic and Near-isotropic Nuclear Graphites
This standard is issued under the fixed designation D 7219; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope NQA-1 Quality Assurance Program Requirements for
Nuclear Facilities
1.1 This specification covers the classification, processing,
and properties of nuclear grade graphite billets with dimen-
3. Terminology
sions sufficient to meet the designer’s requirements for fuel
3.1 Definitions—Definitionsrelatingtothisspecificationare
elements, moderator or reflector blocks, in a high temperature
given in Terminology C 709.
gas cooled reactor. The graphite classes specified here would
3.2 Definitions of Terms Specific to This Standard:
be suitable for reactor core applications where neutron irradia-
3.2.1 apparent porosity—ratio of the volume of open pores
tion induced dimensional changes are a significant design
to the exterior volume expressed as a percentage.
consideration.
3.2.2 baking/re-baking charge—the number of billets in a
1.2 The values stated in SI units are to be regarded as
baking/re-baking furnace run.
standard. No other units of measurement are included in this
3.2.3 bulk density—the mass of a unit volume of material
standard.
including both permeable and impermeable voids.
1.3 This standard does not purport to address all of the
3.2.4 extrusion forming lot—the number of billets of the
safety concerns, if any, associated with its use. It is the
same size extruded in an uninterrupted sequence.
responsibility of the user of this standard to establish appro-
3.2.5 green batch—the mass of coke, recycle green mix,
priate safety and health practices and determine the applica-
recycle graphite, and pitch that is required to produce a
bility of regulatory limitations prior to use.
forming lot.
2. Referenced Documents 3.2.6 graphite billet—an extruded, molded, or iso-molded
graphite artifact with dimensions sufficient to meet the design-
2.1 ASTM Standards:
er’s requirements for reactor components.
C 709 Terminology Relating to Manufactured Carbon and
3.2.7 graphite grade—the designation given to a material
Graphite
byamanufacturersuchthatitisalwaysreproducedtothesame
C 781 PracticeforTestingGraphiteandBoronatedGraphite
specification and from the same raw materials and mix
for High-Temperature Gas-Cooled Nuclear Reactors
formulation.
C 838 Test Method for Bulk Density of As-Manufactured
3.2.8 graphitization charge—the number of billets in a
Carbon and Graphite Shapes
graphitizing furnace run.
C 1233 Practice for Determining Equivalent Boron Con-
3.2.9 high purity nuclear graphite—nuclear graphite whose
tents of Nuclear Materials
Boron Equivalent content is less that 2 ppm.
D 346 Practice for Collection and Preparation of Coke
3.2.10 impregnation charge—the number of billets in an
Samples for Laboratory Analysis
autoclave cycle.
D 2638 Test Method for Real Density of Calcined Petro-
3.2.11 isotropic nuclear graphite—a graphite in which the
leum Coke by Helium Pycnometer
isotropy ratio based on the coefficient of thermal expansion is
2.2 ASME Standard:
1.00 to 1.10.
3.2.12 low purity nuclear graphite—nuclear graphite whose
Boron Equivalent content is greater than 2 ppm but less that 10
This specification is under the jurisdiction of ASTM Committee D02 on
ppm.
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
3.2.13 mix formulation—the percentages of each specifi-
D02.F0 on Manufactured Carbon and Graphite Products.
Current edition approved Nov. 1, 2005. Published December 2005.
cally sized filler used to manufacture a graphite grade.
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D7219–05
TABLE 2 ASTM Graphite Grain Size Definitions from
3.2.14 molding forming lot—the number of billets molded
Terminology C 709
from a molding powder lot.
Definition of
3.2.15 molding powder lot—a sufficient quantity of re-
Graphite Designation
A
Grains in the Starting Mix that are:
milled and blended green batch produced from an uninter-
Medium Grained Generally<4mm
rupted flow of raw materials, or produced in a sequence of
Fine Grained Generally < 100 µm
identical materials batches, to produce a molding forming lot.
Superfine Grained Generally < 50 µm
3.2.16 near isotropic nuclear graphite—a graphite in which Ultrafine Grained Generally < 10 µm
Microfine Grained Generally<2µm
the isotropy ratio based on the coefficient of thermal expansion
A
Grain size as defined in Terminology C 709.
is 1.10 to 1.15.
3.2.17 nuclear graphite class—the designation of a nuclear
graphite based upon its forming method, isotropy, purity and
5.2.1.4 Graphite manufactured in compliance with this
density (see Table 1).
3.2.18 production lot—aspecifiednumberofbilletsmadein specification but failing to meet the property requirements of
Sections 6 and 7 may be used as recycle material in the mix
accordance with this specification as determined by the pur-
chaser. formulation.
3.2.19 purification charge—the number of billets in a puri-
5.2.1.5 Recyclegreenmixmanufacturedfromrawmaterials
fication run. in compliance with this specification may be used in the mix
3.2.20 recycle green mix—ground non-baked billets or non-
formulation.
formed formulation manufactured in compliance with the mix 5.2.1.6 The maximum filler particle size used in the mix
formulation specified here.
formulation shall be 1.68 mm.
5.3 Binder—The binder shall consist of coal tar pitch. The
4. Significance and Use
specific binder used shall be identified to the purchaser and be
4.1 The purpose of this specification is to document the traceable through the forming lot.
minimum acceptable properties and levels of quality assurance 5.4 Impregnant—The impregnant shall consist of a petro-
and traceability for isotropic and near-isotropic nuclear grade leum or coal tar pitch and be traceable through the impregna-
graphites. tion step.
5.5 Manufacturing or Processing Additives—Additives (for
5. Materials and Manufacture
example, extrusion aids) may be used to improve the process-
ing, quality and properties of the product, but only with the
5.1 Nuclear Graphite Classes—See Table 1.
consent and approval of the purchaser, and they must be
5.2 Raw Materials:
traceable through the forming lot.
5.2.1 Fillers:
5.2.1.1 The filler shall consist of a near-isotropic or isotro- 5.6 Manufacture:
5.6.1 Formulation—The mix formulation (as defined in
pic coke derived from a petroleum oil or coal tar.
5.2.1.2 The coke shall have a coefficient of linear thermal 3.2.13) and recycle green mix fraction (as defined in 3.2.20)in
the filler shall be recorded. This information shall be reported
expansion (CTE), determined in accordance with Practice
C 781 and measured over the temperature range 25 to 500°C, to the purchaser if requested.
-6 -6 -1
of between 3.5 3 10 and 5.5 3 10 °C . 5.6.2 Forming—The green carbon mix may be formed by
5.2.1.3 The coke shall be sampled and distributed as de- extrusion, molding (including vibrationally molding), or iso-
scribed in Table 3. molding.
TABLE 1 ASTM Standard Classes of Nuclear Graphite
Purity
B C
CTE Isotropy Ratio Bulk Density,
A
B D
Class Class Designation
Ash Content, Boron Equivalent,
(a /a ) g/cm (min)
AG WG
ppm (max) ppm (max)
Isomolded, isotropic—High Purity 1.0-1.1 300 2 1.7 IIHP
Isomolded, isotropic—Low Purity 1.0-1.1 1000 10 1.7 IILP
Isomolded, near-isotropic—High Purity 1.1-1.15 300 2 1.7 INHP
Isomolded, near-isotropic—Low Purity 1.1-1.15 1000 10 1.7 INLP
Extruded, isotropic—High Purity 1.0-1.1 300 2 1.7 EIHP
Extruded, isotropic—Low Purity 1.0-1.1 1000 10 1.7 EILP
Extruded, near-isotropic—High Purity 1.1-1.15 300 2 1.7 ENHP
Extruded, near-isotropic—Low Purity 1.1-1.15 1000 10 1.7 ENLP
Molded, isotropic—High Purity 1.0-1.1 300 2 1.7 MIHP
Molded, isotropic—Low Purity 1.0-1.1 1000 10 1.7 MILP
Molded, near-isotropic—High Purity 1.1-1.15 300 2 1.7 MNHP
Molded, near-isotropic—Low Purity 1.1-1.15 1000 10 1.7 MNLP
A
These classes may be further modified by the grain size as defined in Terminology C 709.
B
Determined in accordance with Practice C 781.
C
Determined in accordance with Test Method C 838.
D
Determined in accordance with Practice C 1233.
D7219–05
TABLE 3 Inspection Sampling and Testing of Filler Cokes
Raw Material Inspection Plan Sampling Procedure Tests and Test Methods
Filler coke A representative sample of the Sample in accordance with Practice D 346 The procedure in Practice C 781 shall be used to
coke shall be taken prior to the 1. A sufficient sample for preparation of CTE test prepare test specimens for the measurement of
mixing step of manufacture specimens coke CTE
2. A sufficient sample will be taken for additional Measure the coke real density in accordance with
testing. This sample shall be retained for a Test Method D 2638
period specified by the graphite purchaser
TABLE 5 Chemical Purity requirements for LP Class
5.6.3 Graphitization Temperature—The graphitization tem-
Nuclear Graphite
perature shall be determined on each billet using the procedure
Test Practice Specification (ppm)
described in Practice C 781. Each billet tested in accordance
Ash Content C 781 1000 maximum
with Practice C 781 shall have a Specific Electrical Resistivity
Chemical Impurities – Ca C 781 < 100
(SER) corresponding to a graphitization temperature of at least
Chemical Impurities – Co C 781 <0.3
Chemical Impurities – Fe C 781 < 100
2700°C.
Chemical Impurities – Cs C 781 <0.3
Chemical Impurities – V C 781 < 250
6. Chemical Properties
Chemical Impurities – Ti C 781 < 150
Chemical Impurities – Li C 781 <0.6
6.1 Each graphite billet/production lot sampled in accor-
Chemical Impurities – Sc C 781 <0.3
dance with Section 11 shall conform to the requirements for
Chemical Impurities – Ta C 781 <0.3
Boron Equivalent C 1233 10 maximum
chemical purity specified in Table 4 or Table 5, and to the
A
Chemical Impurities – N C 781 to be determined
requirements of the purchaser.
A
Relative Oxidation Rate in Air C 781 to be determined
6.2 The boron equivalent shall be calculated in accordance
A
Data are not currently available to establish this value.
with Practice C 1233. The concentrations of at least the
following elements shall be determined and used in the
TABLE 6 Physical and Mechanical Properties for Nuclear
calculation: Boron, Cadmium, Chlorine, Cobalt, Dysprosium,
Graphite Classes IIHP and IILP
Europium, Gadolinium, Lithium, Manganese, Nickel, Sa-
A
Test Practice Specification
marium, Silver, Titanium, Tungsten, and Vanadium. Specified
Apparent Porosity C 781 14 % max
boron equivalent limits are given in Table 1.
Thermal Conductivity at 25°C, AG C 781 90 W/m·K min
-6 -1
6.3 Table X1.1 contains a list of chemical impurities typi-
Coefficient of Thermal Expansion C 781 3.5-6.0 3 10 °C
(25-500°C), WG
cally found in graphite. The impurities are categorized as
Tensile Strength, WG C 781 22 MPa min
neutron absorbing impurities, oxidation promoting catalysts,
Flexural Strength, WG C 781 35 MPa min
activation relevant impurities, metallic corrosion relevant im-
Compressive Strength, WG C 781 65 MPa min
Dynamic Elastic Modulus, WG C 781 15 GPa max
purities, and fissile/fissionable elements. The suggested limits
Dynamic Elastic Modulus, WG C 781 8 GPa min
represent the reactor designer’s preferences for chemical pu-
Stress-Strain Response and Modulus C 781 7 GPa min
rity.
of Elasticity, WG
Strain to Failure, WG C 781 0.3 % min
Fracture Toughness, WG C 781 0.8 MPa·=mmin
7. Physical and Mechanical Properties
Weibull Modulus, WG C 781 15 min
B
7.1 Each graphite billet/production lot sampled in accor-
Weibull Characteristic Value, WG C 781 to be determined
A
dance with Section 11 shall conform to the requirements for
WG = With Grain; AG = Against Grain.
B
Data are not currently available to establish this value.
physical properties prescribed in Table 1 and Tables 6-11 for
the appropriate nuclear graphite class, and to the requirements
of the purchaser. Table X1.2 is a summary table of the
8. Other Requirements
properties reported in Tables 6-11.
8.1 The graphitized billets shall be handled and stored in
such a manner that they are protected from contaminants other
TABLE 4 Chemical Purity Requirements for HP Class
than ambient air.
Nuclear Graphite
8.2 Each graphite billet shall be marked with a unique billet
Test Practice Specification (ppm)
identification number. Each billet shall be traceable through
Ash Content C 781 300 maximum these identifying numbers to each of the following:
Chemical Impurities – Ca C 781 <30
8.2.1 Formulation designation,
Chemical Impurities – Co C 781 <0.1
8.2.2 Coke batch,
Chemical Impurities – Fe C 781 <30
Chemical Impurities – Cs C 781 <0.1
8.2.3 Recycle graphite batch,
Chemical Impurities – V C 781 <50
8.2.4 Forming lot,
Chemical Impurities – Ti C 781 <50
8.2.5 Molding powder lot,
Chemical Impurities – Li C 781 <0.2
Chemical Impurities – Sc C 781 <0.1
8.2.6 Baking charge,
Chemical Impurities – Ta C 781 <0.1
8.2.7 Impregnant charge,
Boron Equivalent C 1233 2 maximum
A
8.2.8 Graphitizing charge,
Chemical Impurities – N C 781 to be determined
A
Relative Oxidation Rate in Air C 781 to be determined
8.2.9 Position of billet in graphitization furnace,
A
Data are not currently available to establish this value. 8.2.10 Purification step (if performed),
D7219–05
TABLE 7 Physical and Mechanical Properties for Nuclear TABLE 10 Physical and Mechanical Properties for Nuclear
Graphite Classes INHP and INLP Graphite Classes MIHP and MILP
A A
Test Practice Specification Test Practice Specification
Apparent Porosity C 781 14 % max Apparent Porosity C 781 14 % max
Thermal Conductivity at 25°C, AG C 781 80 W/m·K min Thermal Conductivity at 25°C, AG C 781 100 W/m·K min
-6 -1 -6 -1
Coefficient of Thermal Expansion C 781 3.5-6.0 3 10 °C Coefficient of Thermal Expansion C 781 3.5-6.0 3 10 °C
(25-500°C), WG (25-500°C), WG
Tensile Strength, WG C 781 20 MPa min Tensile Strength, WG C 781 15 MPa min
Flexural Strength, WG C 781 30 MP
...
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