Nuclear Graphite
ASTM D7219
Nuclear Graphite is high-purity, low-boron isotropic or near-isotropic synthetic graphite qualified to nuclear specifications such as D7219, with reactor grades including IG-110, IG-430, NBG-18 and PCEA.
Reference datasheet — Nuclear Graphite is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the IG-110 condition
Nuclear Graphite tempers and conditions
Nuclear Graphite is supplied in 4 conditions, soft to hard. IG-110 is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Extruded medium-grain petroleum-coke nuclear graphite | Use where large extruded sections and cost matter and mild property anisotropy (with-grain vs against-grain) is acceptable; strength is lower than isostatic grades. | 17 | 140 W/m·K | |||
Vibration-molded medium-grain pitch-coke near-isotropic nuclear graphite | Choose for large pebble-bed reflector blocks where big billet sizes, high thermal conductivity and low irradiation-induced dimensional change dominate over fine grain size. | 22 | 150 W/m·K | |||
IG-110Default Isostatically molded superfine-grain isotropic nuclear graphite | Default choice for HTGR/HTR-PM fuel blocks, reflectors and molten-salt reactor components where fine grain (~20 µm), high isotropy and proven irradiation database matter. | 25 | 120 W/m·K | |||
High-density isostatic fine-grain nuclear graphite | Pick when higher strength and density than IG-110 are needed for control-rod sleeves, high-stress reflector parts or MSR components. | 37 | 140 W/m·K |
What is Nuclear Graphite?
Nuclear Graphite is high-purity, low-boron isotropic or near-isotropic synthetic graphite qualified to nuclear specifications such as D7219, with reactor grades including IG-110, IG-430, NBG-18 and PCEA. It is selected as moderator, reflector and structural material for its neutron behaviour, 120 W/m·K conductivity and capability to 2500 °C in inert or vacuum conditions, and is supplied as baked, impregnated and graphitised blocks for machining. Strength is low and brittle (25 MPa tensile, 9.8 GPa modulus), it oxidises in air above roughly 500 °C, and qualification, purification and lead times raise cost sharply. Standard fine-grain isostatic graphite is the alternative outside nuclear service. Nuclear Graphite has a density of 1.78 g/cm³ (0.0643 lb/in³), lighter than 90% of ceramic grades. It melts at 3,650°C (6,602 °F). Nuclear Graphite has a tensile strength of 25 MPa (3.63 ksi), weaker than 85% of ceramic grades. The elastic modulus is 9.8 GPa (1.42 Msi).
What is Nuclear Graphite used for?
- reactor moderator blocks
- reflector components
- fuel element sleeves
- HTGR structural parts
Advantages
- High service temperature — 2,500°C (4,532 °F), better than 98% of ceramic grades
- Easy to machine — 93/100, better than 98% of ceramic grades
- Lightweight — 1.78 g/cm³ (0.0643 lb/in³), better than 90% of ceramic grades
- Conducts heat well — 120 W/m·K (69.3 BTU/hr·ft·°F), better than 88% of ceramic grades
Limitations
- Low fracture toughness — 0.9 MPa·√m (0.819 ksi·√in), worse than 96% of ceramic grades
- Low stiffness — 9.8 GPa (1.42 Msi), worse than 94% of ceramic grades
- Hard to polish — 35/100, worse than 93% of ceramic grades
Nuclear Graphite properties
Typical room-temperature values for Nuclear Graphite-IG-110; bars are the position among ceramic grades.
Physical3
Nuclear Graphite has a density of 1.78 g/cm³ (0.0643 lb/in³), lighter than 90% of ceramic grades. It melts at 3,650°C (6,602 °F).
Mechanical10
Nuclear Graphite has a tensile strength of 25 MPa (3.63 ksi), weaker than 85% of ceramic grades. The elastic modulus is 9.8 GPa (1.42 Msi).
Thermal5
Nuclear Graphite is rated for continuous service to 2,500°C (4,532 °F). It conducts heat at 120 W/m·K (69.3 BTU/hr·ft·°F), better than 88% of ceramic grades. Thermal expansion is 4.5 µm/m·K (2.5 µin/in·°F).
Electrical2
Nuclear Graphite has an electrical resistivity of 1.1×10⁻⁵ Ω·m.
Chemical & Environmental2
Corrosion resistance is very good (75/100), better than 50% of ceramic grades.
Sustainability4
Producing a kilogram of Nuclear Graphite takes about 180 MJ of energy and emits 14 kg of CO₂ — more than 60% of ceramic grades. Typical recycled content is 0%.
Manufacturability3
Nuclear Graphite's machinability is excellent (93/100, better than 98% of ceramic grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the ceramic family
Yield strength against density for every ceramic grade FabDigit runs. Nuclear Graphite is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Nuclear Graphite
Is Nuclear Graphite easy to machine?
Machines dry very easily with carbide or PCD tooling at high speed, but the dust is abrasive, electrically conductive and must be vacuum-extracted; avoid cutting fluids that contaminate the pores.
Can Nuclear Graphite be welded?
Not weldable — parts are joined mechanically (threaded keys, dowels, graphite bolts) or with carbonaceous cements that are carbonized/graphitized after assembly.
Can Nuclear Graphite be formed, bent or molded?
Formed only at the green stage by isostatic pressing, vibration molding or extrusion of coke/pitch mix, then baked, pitch-impregnated, graphitized >2800 °C and halogen-purified; finished blocks are shaped only by machining.
Nuclear Graphite chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| ashtotal ash, typically <20–300 ppm depending on grade | ≤ 0.03 | 0 |
| Bboron equivalent typically ≤2 ppm per ASTM D7219 | ≤ 2×10⁻⁴ | 5×10⁻⁵ |
| Vresidual from petroleum coke | ≤ 5×10⁻⁴ | 1×10⁻⁴ |
| Fe | ≤ 0 | 2×10⁻⁴ |
| S | ≤ 0.01 | 0 |
| Cafter halogen purification | ≥ 99.95 (balance) |
What surface finishes work on Nuclear Graphite?
Surfaces are typically machined and cleaned by baking/vacuum outgassing; optional SiC or pyrolytic-carbon CVD coatings or phosphate-based antioxidants improve oxidation resistance above 500 °C.
Equivalent designations
Standards and trade names that resolve to Nuclear Graphite in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- D7219
How much does Nuclear Graphite cost?
Nuclear Graphite is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Nuclear Graphite — frequently asked
What is Nuclear Graphite used for?
Nuclear Graphite is typically used for reactor moderator blocks, reflector components, fuel element sleeves and HTGR structural parts. In short: nuclear-qualified isotropic graphite; low boron, high purity; brittle, low tensile strength.
What is the tensile strength of Nuclear Graphite?
Nuclear Graphite has a typical tensile strength of 25 MPa (3.63 ksi) — weaker than 85% of ceramic grades. Strength varies by condition: see the 4 listed tempers.
Is Nuclear Graphite easy to machine?
Yes — machinability is rated excellent (93/100, better than 98% of ceramic grades). Machines dry very easily with carbide or PCD tooling at high speed, but the dust is abrasive, electrically conductive and must be vacuum-extracted; avoid cutting fluids that contaminate the pores.
Can Nuclear Graphite be welded?
Not weldable — parts are joined mechanically (threaded keys, dowels, graphite bolts) or with carbonaceous cements that are carbonized/graphitized after assembly.
What surface finishes work on Nuclear Graphite?
Surfaces are typically machined and cleaned by baking/vacuum outgassing; optional SiC or pyrolytic-carbon CVD coatings or phosphate-based antioxidants improve oxidation resistance above 500 °C.
Can Nuclear Graphite be formed, bent or molded?
Formed only at the green stage by isostatic pressing, vibration molding or extrusion of coke/pitch mix, then baked, pitch-impregnated, graphitized >2800 °C and halogen-purified; finished blocks are shaped only by machining.
What is the maximum service temperature of Nuclear Graphite?
Nuclear Graphite is rated for continuous use to about 2,500°C (4,532 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Nuclear Graphite cost?
Nuclear Graphite is a high-cost ceramic ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM D7219 — Standard Specification for Isotropic and Near-isotropic Nuclear Graphites — ASTM International (2019)
- ASTM D7301 — Standard Specification for Nuclear Graphite Suitable for Components Subjected to Low Neutron Irradiation Dose — ASTM International (2018)
- Isotropic Graphite IG-110 / IG-430 technical data — Toyo Tanso (2020)
- NBG-18 nuclear graphite grade data — SGL Carbon (2019)
- Graphite Design Handbook / NGNP Graphite Testing and Qualification (INL/EXT reports) — Idaho National Laboratory (2011)
- IAEA-TECDOC-1154: Irradiation Damage in Graphite due to Fast Neutrons in Fission and Fusion Systems — IAEA (2000)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.