spore: profile
id: sodium
spore_version: 0.2
family: alkali-and-alkaline-earth-metals
name: Sodium
abbreviation: Na
role: coolant
category: metals
type: magnesium
summary: |
  Sodium is a soft, silvery alkali metal, less dense than water. At ordinary pressure it stays liquid from 97.82 C to 881.4 C, and it carries heat well, so it is the coolant of sodium-cooled fast reactors. Its weakness is chemistry: it reacts violently with water, may ignite spontaneously in moist air, and burns in oxygen. Sodium is also the anode of high-temperature sodium-sulfur cells, which run above 300 C with molten electrodes.
best_for: Heat transfer in a liquid metal at high temperature and low pressure, as in fast-reactor coolant loops
weakest_at: Any contact with water, moist air or oxygen. It reacts violently, may ignite and must be kept dry and under inert cover
identity:
  formula: Na
  cas: 7440-23-5
  source: pubchem-sodium
  where: Names and Identifiers (CAS entry), PubChem CID 5360545
tags:
  environments: []
  stresses: []
  applications:
    - thermal-control
    - batteries
properties:
  - benchmark: density
    label: Density
    value: 0.968
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 C
    method: Merck Index value as printed in PubChem (printed as g/cu cm, written here as g/cm3)
    status: ground
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Density (Merck Index, 13th edition)
  - benchmark: density
    label: Liquid density
    value: 919
    unit: kg/m3
    scope: material
    conditions:
      phase: liquid
      temperature: 400 K
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 1.3-1, Sodium Density, liquid density column, 400 K row
  - benchmark: density
    label: Liquid density
    value: 828
    unit: kg/m3
    scope: material
    conditions:
      phase: liquid
      temperature: 800 K
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 1.3-1, Sodium Density, liquid density column, 800 K row
  - benchmark: melting_point
    label: Melting point
    value: 97.82
    unit: C
    scope: material
    conditions:
      pressure: ambient, not stated by source
    method: Merck Index value as printed in PubChem
    status: ground
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Melting Point (Merck Index)
  - benchmark: boiling_point
    label: Boiling point
    value: 881.4
    unit: C
    scope: material
    conditions:
      pressure: not stated by source
    method: Merck Index value as printed in PubChem
    status: ground
    note: PubChem also lists 882.94 C at 760 mmHg and 880 C from other handbooks. The 881.4 C Merck value is used here; the MDPI sodium paper gives 881 C in its Table 1.
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Boiling Point (Merck Index, 13th edition)
  - benchmark: specific_heat
    label: Specific heat, liquid
    value: 1.372
    unit: kJ/kg K
    scope: material
    conditions:
      phase: liquid
      temperature: 400 K
      basis: constant pressure
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 1.1-5, Heat Capacity of Liquid Sodium, Cp column, 400 K row
  - benchmark: specific_heat
    label: Specific heat, liquid
    value: 1.252
    unit: kJ/kg K
    scope: material
    conditions:
      phase: liquid
      temperature: 900 K
      basis: constant pressure
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 1.1-5, Heat Capacity of Liquid Sodium, Cp column, 900 K row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, liquid
    value: 87.22
    unit: W/m K
    scope: material
    conditions:
      phase: liquid
      temperature: 400 K
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 2.1-1, Thermal Conductivity of Liquid Sodium, 400 K row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, liquid
    value: 62.9
    unit: W/m K
    scope: material
    conditions:
      phase: liquid
      temperature: 800 K
    method: Recommended value of the Argonne report, read from its table
    status: ground
    source: fink-leibowitz-1995
    where: Table 2.1-1, Thermal Conductivity of Liquid Sodium, 800 K row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, solid
    value: 132.3
    unit: W/m K
    scope: material
    conditions:
      temperature: 293.15 K
      note: below the melting point, so solid
    method: Ullmann's Encyclopedia value as printed in PubChem
    status: ground
    source: pubchem-sodium
    where: 'Chemical and Physical Properties > Experimental Properties, entry ''thermal conductivity: 132.3W/m K at 293.15 K'' (Ullmann''s)'
  - benchmark: electrical_resistivity
    label: Electrical resistivity
    value: 4.77
    unit: microohm cm
    scope: material
    conditions:
      temperature: 293 K
      unit_in_source: 4.77x10-8 Ohm m
    method: 'Ullmann''s value as printed in PubChem (4.77x10-8 Ohm m), converted by the editors: 1 Ohm m = 10^8 microohm cm'
    status: ground
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties, entry 'electrical resistivity' (Ullmann's)
  - benchmark: vapor_pressure
    label: Vapor pressure
    value: 5.6
    unit: Pa
    scope: material
    conditions:
      temperature: 600 K (327 C)
    method: CRC Handbook value as printed in PubChem (the same entry gives 0.000185 Pa at 400 K)
    status: ground
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Vapor Pressure (Lide, CRC Handbook)
  - benchmark: dynamic_viscosity
    label: Dynamic viscosity, liquid
    value: 0.68
    unit: cP
    scope: material
    conditions:
      temperature: 100 C
    method: Kirk-Othmer value as printed in PubChem
    status: ground
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Viscosity (Kirk-Othmer)
  - benchmark: autoignition_temperature
    label: Autoignition temperature
    value: 115
    bound: lower
    unit: C
    scope: material
    conditions:
      atmosphere: dry air
    method: Sax handbook value as printed in PubChem (above 115 C in dry air)
    status: ground
    note: PubChem also lists 250 F (USCG) and 120 to 125 C without a stated method. The Sax dry-air figure is used here.
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Autoignition Temperature (Sax)
  - benchmark: theoretical_capacity
    label: Theoretical capacity of sodium metal
    value: 1166
    unit: mAh/g
    scope: material
    conditions:
      reaction: Na to Na+, one electron per atom
      electrode: sodium metal anode
    method: Value stated by the review (it gives the figure without a derivation)
    status: calculated
    source: na-s-review-2023
    where: Text on the theoretical energy of Na-S batteries, paragraph naming Na (1166 mA h/g) and S (1672 mA h/g)
  - benchmark: theoretical_specific_energy
    label: Theoretical specific energy, sodium-sulfur
    value: 1274
    unit: Wh/kg
    scope: cell
    conditions:
      couple: sodium and sulfur
      basis: theoretical
    method: Value stated by the review, which cites its reference 47
    status: calculated
    source: na-s-review-2023
    where: Text on Na-S and Li-S chemistry, sentence 'The theoretical capacity of the Na-S battery is 1274 Wh/kg'
  - benchmark: cell_specific_energy
    label: Energy density, high-temperature Na-S cell
    value: 200
    bound: lower
    unit: Wh/kg
    scope: cell
    conditions:
      battery: high-temperature sodium-sulfur
      operating_temperature: above 300 C
    method: Table value as printed in the review (energy density 200 Wh/kg or higher)
    status: ground
    source: na-s-review-2023
    where: Table, Electrochemical Performance of Na-S Batteries, High Temperature column, Energy density row
  - benchmark: cell_specific_energy
    label: Energy density, room-temperature Na-S cell
    value: 150
    value_high: 240
    unit: Wh/kg
    scope: cell
    conditions:
      battery: room-temperature sodium-sulfur
    method: Table value as printed in the review (150 to 240 Wh/kg)
    status: ground
    source: na-s-review-2023
    where: Table, Electrochemical Performance of Na-S Batteries, Room Temperature column, Energy density row
  - benchmark: operating_temperature
    label: Operating temperature, high-temperature Na-S
    value: 300
    bound: lower
    unit: C
    scope: cell
    conditions:
      battery: high-temperature sodium-sulfur
      purpose: keeps the sulfur cathode and sodium anode molten
    method: Review statement that these batteries normally operate above 300 C
    status: ground
    source: na-s-review-2023
    where: Introduction, sentence beginning 'Normally, Na-S batteries operate at high temperatures above 300 C'
corrosion:
  - environment: Liquid water
    headline: Sodium reacts violently with water, releasing hydrogen and caustic soda, and the hydrogen can ignite.
    effect: Reacts violently with water to form hydrogen gas and caustic soda solution. The hydrogen ignites and explodes in air.
    rating: severe
    conditions:
      state: any water contact
    source: pubchem-sodium
    where: Safety and Hazards > Stability and Reactivity > Hazardous Reactivities and Incompatibilities; Air and Water Reactions
  - environment: Moist air at room temperature
    headline: Sodium may ignite spontaneously in moist air, and the surface tarnishes in air.
    effect: Combustible solid that may ignite spontaneously on exposure to moist air. Decomposes rapidly under air and moisture, forming flammable hydrogen. Tarnishes on exposure to air, becoming dull and gray.
    rating: severe
    conditions:
      atmosphere: moist air, room temperature
    source: pubchem-sodium
    where: Safety and Hazards > Hazards Identification > Fire Potential; Chemical Dangers; Chemical and Physical Properties > Stability/Shelf Life
  - environment: Dry air below 1000 F (as printed)
    headline: In dry air and without hydrogen, the reaction is slow below 1000 F.
    effect: In the absence of moisture and hydrogen the reaction with air is insignificant below 1000 F, as printed. Vapor ignites at room temperature and droplets near 250 F.
    rating: moderate
    conditions:
      atmosphere: dry air, no moisture or hydrogen
      temperature: below 1000 F as printed
    source: pubchem-sodium
    where: Safety and Hazards > Hazards Identification > Fire Potential (NFPA 2002 guide)
  - environment: Oxygen, and hot sodium in air
    headline: Sodium reacts vigorously with oxygen, burning with a yellow flame.
    effect: Reacts vigorously with oxygen, burning with a yellow flame. Above 115 C in air it ignites and gives a strongly alkaline sodium peroxide fume.
    rating: severe
    conditions:
      temperature: above 115 C in air
    source: pubchem-sodium
    where: Safety and Hazards > Stability and Reactivity > Hazardous Reactivities; Other Safety Information > Toxic Combustion Products
  - environment: Sodium pool with oxygen, in a reactor
    headline: Sodium-oxygen reaction in a pool is the main fire hazard of a sodium-cooled reactor.
    effect: The sodium-oxygen reaction is the fire hazard in sodium-cooled fast reactors, and sodium pool fire design is the basis of accidents in them. The authors measure the thermal behavior of sodium in diluted oxygen.
    rating: severe
    conditions:
      atmosphere: diluted oxygen, sodium pool
    source: sfr-sodium-fire-2022
    where: Abstract and Introduction
  - environment: Mineral oil or kerosene (storage and cover)
    headline: Sodium is stored under mineral oil and is insoluble in kerosene.
    effect: Stored under mineral oil and kept dry. Sodium is insoluble in benzene, kerosene and naphtha. Kerosene, paraffin oil or dry sand are listed to cover spilled sodium.
    rating: low
    conditions:
      liquid: mineral oil, kerosene or paraffin oil, dry
    source: pubchem-sodium
    where: Chemical and Physical Properties > Experimental Properties > Solubility; Safety and Hazards > Handling and Storage > Safe Storage
  - environment: Carbon dioxide at high temperature
    headline: Hot sodium and carbon dioxide can form explosive mixtures.
    effect: Sodium and carbon dioxide are normally unreactive until red heat, but mixtures of the two solids are impact-sensitive and explode violently. Carbon dioxide is unsuitable for putting out burning sodium.
    rating: severe
    conditions:
      temperature: red heat and above
    source: pubchem-sodium
    where: Safety and Hazards > Fire Fighting > Fire Fighting Procedures (Merck and NFPA)
  - environment: Halogens, acids and halogenated hydrocarbons
    headline: Sodium reacts exothermically with halogens, acids and halogenated hydrocarbons.
    effect: Reacts exothermally with halogens, acids and halogenated hydrocarbons. Anhydrous hydrogen chloride, hydrogen fluoride and sulfuric acid react slowly, while aqueous solutions react explosively.
    rating: severe
    conditions:
      state: contact at normal handling
    source: pubchem-sodium
    where: Safety and Hazards > Stability and Reactivity > Hazardous Reactivities and Incompatibilities (Sax, Bretherick)
  - environment: Type 316L austenitic stainless steel in pure sodium at 600 to 700 C
    headline: Type 316L stainless steel was largely immune to sodium exposure in screening tests.
    effect: Capsule tests at 600 or 700 C for 100 and 400 h, and thermal convection loops for 2000 h, showed 316L largely immune to changes from commercially pure sodium, with no mass transfer seen in the loops.
    rating: low
    conditions:
      material: 316L in commercially pure sodium
      temperature: 600 to 700 C
    source: pawel-2012-ornl
    where: Abstract
  - environment: NF-616 ferritic steel in sodium at 700 C
    headline: The ferritic steel NF-616 decarburizes substantially in sodium at 700 C.
    effect: NF-616 was found susceptible to substantial decarburization at 700 C in sodium. The same test found the HT-UPS and 316L alloys largely immune.
    rating: moderate
    conditions:
      material: NF-616 ferritic steel
      temperature: 700 C
    source: pawel-2012-ornl
    where: Abstract
risks:
  hazards:
    - text: Classified Danger. In contact with water it releases flammable gases which may ignite spontaneously (H260, 100% of ECHA notifications). It causes severe skin burns and eye damage (H314, 100%).
      ghs:
        - H260
        - H314
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > GHS Classification (ECHA C&L, 439 reports from 9 notifications)
    - text: Serious eye damage (H318) is notified in 45.1% of ECHA reports.
      ghs:
        - H318
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > GHS Classification (ECHA C&L)
    - text: 'Transport: UN1428, Division 4.3 (dangerous when wet), packing group I.'
      ghs: []
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > DOT Hazard Classification (49 CFR 173.124)
    - text: Vapor ignites at room temperature, droplets at about 250 F and an agitated pool at 400 F. In the absence of moisture and hydrogen the reaction is insignificant below 1000 F.
      ghs: []
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > Fire Potential (NFPA 2002 guide)
    - text: Above 115 C in air, sodium may ignite and produce a strongly alkaline sodium peroxide fume, a serious hazard for inhalation and for skin and eye contact.
      ghs: []
      source: pubchem-sodium
      where: Safety and Hazards > Other Safety Information > Toxic Combustion Products
    - text: Vapors and fumes from sodium are strongly alkaline and highly irritating and corrosive to the respiratory tract, eyes and skin.
      ghs: []
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > Skin, Eye, and Respiratory Irritations (Patty's Toxicology)
  failure_risks:
    - mode: Water entering a sodium loop
      trigger: Water or steam contacts the molten or solid sodium
      consequence: Violent reaction, flammable hydrogen gas that may ignite, and caustic soda solution.
      severity: high
      source: pubchem-sodium
      where: Safety and Hazards > Stability and Reactivity > Air and Water Reactions
    - mode: Sodium pool fire after a leak
      trigger: Sodium leaks into air in a sodium-cooled reactor
      consequence: A sodium-oxygen fire. The authors describe sodium pool fire design as the basis of accidents in these reactors.
      severity: high
      source: sfr-sodium-fire-2022
      where: Abstract
    - mode: Spontaneous ignition in moist air
      trigger: Exposure of sodium vapor, droplets or a finely divided form to moist air
      consequence: Spontaneous ignition. Vapor ignites at room temperature.
      severity: high
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > Fire Potential
    - mode: Fire fighting with the wrong agent
      trigger: Water, foam or carbon dioxide applied to a sodium fire
      consequence: Water and foam produce hydrogen and can cause explosion. Carbon dioxide mixed with hot sodium is impact-sensitive and can explode.
      severity: high
      source: pubchem-sodium
      where: Safety and Hazards > Fire Fighting (ERG 2024 Guide 138); Fire Fighting Procedures
    - mode: Decarburization of ferritic steel in contact with sodium
      trigger: NF-616 ferritic steel held in sodium at 700 C
      consequence: Substantial decarburization, so the steel loses carbon and strength.
      severity: moderate
      source: pawel-2012-ornl
      where: Abstract
  side_effects:
    - text: Burns and caustic fumes on the skin, eyes and airways from sodium and its reaction products.
      affects: People handling sodium
      source: pubchem-sodium
      where: Safety and Hazards > Hazards Identification > Hazards Summary
    - text: Sodium peroxide fume from burning sodium is strongly alkaline.
      affects: Surroundings and people nearby
      source: pubchem-sodium
      where: Safety and Hazards > Other Safety Information > Toxic Combustion Products
  handling:
    - text: 'Storage: fireproof, dry, well closed and kept under mineral oil. Store cool and dry, well ventilated, separate from water.'
      source: pubchem-sodium
      where: Safety and Hazards > Handling and Storage > Safe Storage; Storage Conditions
    - text: 'Fire: do not use water or foam. A small fire needs dry chemical, soda ash, lime or sand. A large fire needs dry sand, dry chemical, soda ash or lime.'
      source: pubchem-sodium
      where: Safety and Hazards > Fire Fighting > Excerpt from ERG Guide 138
    - text: 'Spill: absorb the spilled sodium dry, cover the remainder with kerosene, paraffin oil or dry sand, and remove the last traces with methylated spirit.'
      source: pubchem-sodium
      where: Safety and Hazards > Accidental Release Measures > Cleanup Methods
    - text: 'Fire extinguishing: improved methods use low-melting inorganic powder mixtures, which melt and form a protective crust on the sodium.'
      source: pubchem-sodium
      where: Safety and Hazards > Fire Fighting > Fire Fighting Procedures
  mitigations:
    - text: Low-melting inorganic powder mixtures melt and form a protective crust over burning liquid sodium.
      source: pubchem-sodium
      where: Safety and Hazards > Fire Fighting > Fire Fighting Procedures
    - text: In capsule and convection-loop tests in commercially pure sodium at 600 to 700 C, Type 316L was largely immune to changes from the sodium (laboratory tests).
      source: pawel-2012-ornl
      where: Abstract
uses:
  - application: thermal-control
    device: Stainless steel and sodium heat pipe, a radiator element for a nuclear electric propulsion spacecraft (test article)
    example: A 4.42 m long heat pipe of 2 cm diameter, tested at 920 K, carried a non-limited power of 3560 W, above its 2600 W design power. The report was prepared for JPL under NASA contract NAS 7-100.
    source: ntrs-nep-heat-rejection-1982
    where: Summary (test of the stainless steel/sodium heat pipe)
  - application: batteries
    device: High-temperature sodium-sulfur battery
    example: Sodium-sulfur cells run above 300 C so that the sulfur and sodium stay molten. The review gives an energy density of 200 Wh/kg or higher for high-temperature Na-S cells.
    source: na-s-review-2023
    where: Introduction; Electrochemical Performance of Na-S Batteries table
  - application: thermal-control
    device: Liquid sodium coolant of a sodium-cooled fast reactor
    example: Liquid sodium is described as an ideal coolant for fast neutron reactors. Sodium pool fire design is the basis of accident analysis for these reactors.
    source: sfr-sodium-fire-2022
    where: Introduction and Abstract
supply:
  - subject: 'Sodium feedstock: salt (sodium chloride). Sodium metal producers were not reviewed for this profile.'
    abundance: The USGS salt chapter says the oceans contain a virtually inexhaustible supply of salt. World mine production of salt in 2025 was about 270,000 thousand metric tons (rounded).
    producers:
      - country: China
        share_percent: 20.7
        year: 2025
      - country: India
        share_percent: 11.1
        year: 2025
      - country: Germany
        share_percent: 5.6
        year: 2025
    critical_lists: []
    recycling: Not reviewed for this profile.
    substitutes: []
    source: usgs-salt-2026
    where: World Production and Reserves table, 2025 column (thousand metric tons). Shares are computed by the editors from the printed 2025 production over the printed world total of 270,000 thousand metric tons, which is rounded, so the shares are approximate.
media: []
documents:
  - title: 'PubChem: Sodium (CID 5360545), properties, hazards and safety record'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5360545/JSON
    year: 2026
  - title: 'NIST Atomic Weights and Isotopic Compositions: Sodium'
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Na&ascii=html
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Salt'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-salt.pdf
    year: 2026
  - title: 'Argonne ANL/RE-95/2: Thermodynamic and Transport Properties of Sodium Liquid and Vapor (copy at University of Brighton)'
    type: report
    url: https://researchdata.brighton.ac.uk/id/eprint/258/3/Thermodynamic%20and%20transport%20porperties%20of%20sodium%20liquid%20and%20vapor.pdf
    year: 1995
  - title: 'NASA NTRS 19830010576: Study of a Heat Rejection System for the Nuclear Electric Propulsion Spacecraft (Thermacore, NASA-CR-169921)'
    type: report
    url: https://ntrs.nasa.gov/api/citations/19830010576/downloads/19830010576.pdf
    year: 1982
  - title: 'Research on Wide-Temperature Rechargeable Sodium-Sulfur Batteries: Features, Challenges and Solutions (PMC10300782)'
    type: paper
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10300782/
    year: 2023
  - title: Thermal Characteristic Analysis of Sodium in Diluted Oxygen via Thermogravimetric Approach (Processes 2022, 10, 704)
    type: paper
    url: https://mdpi-res.com/d_attachment/processes/processes-10-00704/article_deploy/processes-10-00704.pdf
    year: 2022
  - title: Pawel, S. J., Compatibility of HT-UPS and 316L stainless steels with sodium (Fusion Science and Technology 61(1T), 2012)
    type: paper
    url: https://ornl.gov/publication/compatibility-assessment-advanced-stainless-steels-sodium
    year: 2012
gaps:
  - 'Sodium metal producers, their countries and the production route: no source was read in this run, so the supply section gives only the salt feedstock.'
  - 'Critical-mineral status of sodium: the USGS and EU lists were not read for sodium, so critical_lists is empty.'
  - 'Crystal system and space group of sodium: no source was opened for this profile, so left out.'
  - 'Gas or oxide growth rate of sodium in air: not reviewed for this profile. Only qualitative statements from PubChem were used.'
  - 'Corrosion of sodium by carbon steel, nickel alloys and other structural metals with ratings: only the 316L and NF-616 comparison was read (Pawel 2012).'
  - 'Outlet temperatures of sodium-cooled fast reactors: a search snippet gave 510 to 550 C, but no fetched page was read for it, so it is left out.'
  - 'Thermal conductivity of 142 W/m K in the MDPI Table 1: no temperature is stated, so it is not used.'
  - 'Reduction potential of Na/Na+ (2.714 V, printed as a positive number in PubChem): the sign convention is not confirmed by a source, so it is not used.'
  - 'Heat of fusion: PubChem prints 27.05 cal/g in an entry whose source is not clear, so it is not used.'
  - 'Sodium-ion cell data (energy, cycle life, cathode pairings): not reviewed for this profile. The review was used only for the sodium metal capacity.'
  - 'Sodium-potassium alloy NaK: not profiled here. The heat-pipe test used sodium only.'
  - 'Photographs of sodium: no images were fetched in this run, so the media list is empty.'
  - 'Environment tags: none applied, because no source read in this run describes sodium in a space environment.'
  - 'Property names not in property-canon.yaml: operating_temperature, autoignition_temperature, dynamic_viscosity, theoretical_capacity and theoretical_specific_energy. The canonical names density, melting_point, boiling_point, specific_heat, thermal_conductivity, electrical_resistivity and vapor_pressure were used where they fit.'
  - Heat of vaporization (Kirk-Othmer, printed 3.874X10+6 J/kg) and critical temperature (2508.7 K) were dropped because their printed form did not match the PubChem text on the value check.
  - 'Type: the taxonomy has no alkali-metal type under metals, so type is set to magnesium as the nearest light reactive metal. An alkali-metal type would need an edit to src/data/taxonomy.ts, which was outside this task.'
sources:
  pubchem-sodium:
    title: PubChem compound record, Sodium (CID 5360545), with Merck Index, Kirk-Othmer, Ullmann's, CHRIS, ECHA C&L, DOT and ERG 2024 excerpts
    id: PubChem CID 5360545
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5360545/JSON
    year: 2026
    kind: database
    license: public domain (NCBI); contributed data keep their own terms
  nist-atomic-weights:
    title: NIST Atomic Weights and Isotopic Compositions for Sodium (standard atomic weight line)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Na&ascii=html
    year: 2026
    kind: database
    license: public domain (US government work)
  usgs-salt-2026:
    title: Mineral Commodity Summaries 2026, Salt
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-salt.pdf
    year: 2026
    kind: report
    license: public domain
  fink-leibowitz-1995:
    title: ANL/RE-95/2, Thermodynamic and Transport Properties of Sodium Liquid and Vapor (J. K. Fink and L. Leibowitz, Argonne National Laboratory, January 1995)
    id: ANL/RE-95/2
    url: https://researchdata.brighton.ac.uk/id/eprint/258/3/Thermodynamic%20and%20transport%20porperties%20of%20sodium%20liquid%20and%20vapor.pdf
    year: 1995
    kind: report
    license: US government report
  ntrs-nep-heat-rejection-1982:
    title: Study of a Heat Rejection System for the Nuclear Electric Propulsion (NEP) Spacecraft, Thermacore final report for JPL, NASA-CR-169921 (Donald M. Ernst)
    id: NTRS 19830010576
    url: https://ntrs.nasa.gov/api/citations/19830010576/downloads/19830010576.pdf
    year: 1982
    kind: report
    license: public domain (US Government work)
  na-s-review-2023:
    title: 'Research on Wide-Temperature Rechargeable Sodium-Sulfur Batteries: Features, Challenges and Solutions'
    id: PMC10300782
    url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10300782/
    year: 2023
    kind: paper
    license: open access (PubMed Central)
  sfr-sodium-fire-2022:
    title: Thermal Characteristic Analysis of Sodium in Diluted Oxygen via Thermogravimetric Approach, Processes 2022, 10, 704
    id: doi:10.3390/pr10040704
    url: https://mdpi-res.com/d_attachment/processes/processes-10-00704/article_deploy/processes-10-00704.pdf
    year: 2022
    kind: paper
    license: CC BY 4.0
  pawel-2012-ornl:
    title: Compatibility assessment of advanced stainless steels with sodium (Pawel, Fusion Science and Technology 61, 2012)
    url: https://ornl.gov/publication/compatibility-assessment-advanced-stainless-steels-sodium
    year: 2012
    kind: paper
    license: publisher record (ORNL)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 19
  unreachable: 0
  caveats: 2
  note: Written by an AI assistant on 2026-10-26 from pages and PDFs fetched in this run. Two values were converted or computed by the editors (electrical resistivity, supply shares); the rest are printed as in their sources.
story:
  recipe:
    line: Sodium metal is the pure element, Na, with one atom per formula unit. It is not an alloy in this profile.
    parts:
      - name: Sodium
        symbol: Na
        atoms: 1
        atomic_weight: 22.98976928
        role: The only element in the metal. The atomic weight is the NIST standard value.
  why: Sodium is a soft, silvery metal less dense than water (0.968 g/cm3 at 20 C). At ordinary pressure it is liquid from 97.82 C to 881.4 C, which lets a sodium-cooled fast reactor run hot without high pressure. It carries heat well, with a thermal conductivity of 87.22 W/m K at 400 K. Its problem is chemistry. It reacts violently with water, may ignite spontaneously in moist air, and burns with a yellow flame in oxygen. A sodium leak is therefore a fire and hydrogen hazard, and sodium fire design is a core part of sodium-cooled reactor safety.
  uses:
    - where: Sodium-cooled fast reactors
      line: Liquid sodium is described as an ideal coolant for fast neutron reactors. The 2022 study states that sodium pool fire design is the basis of accidents in these reactors.
    - where: Heat pipes for spacecraft radiators
      line: A 1982 Thermacore study for NASA's nuclear electric propulsion spacecraft tested a stainless steel and sodium radiator heat pipe, 4.42 m long and 2 cm in diameter. At 920 K it carried 3560 W with no power limit, above its 2600 W design power.
    - where: High-temperature sodium-sulfur batteries
      line: Sodium-sulfur cells run above 300 C with molten electrodes. The review gives 200 Wh/kg or higher for high-temperature cells, and 1274 Wh/kg as the theoretical energy of the sodium-sulfur couple.
  can_do:
    - label: Liquid range
      value: 97.82 C to 881.4 C
      line: Sodium melts at 97.82 C and boils at 881.4 C at ordinary pressure, so it stays liquid across a wide temperature range.
    - label: Heat transfer
      value: 87.22 W/m K at 400 K
      line: Liquid sodium conducts heat at 87.22 W/m K at 400 K and 62.9 W/m K at 800 K, from the Argonne recommended values.
    - label: Charge per gram
      value: 1166 mAh/g
      line: The theoretical capacity of sodium metal as an anode is 1166 mAh/g, the figure the review uses.
    - label: Cell energy
      value: 200 Wh/kg or higher
      line: The review gives an energy density of 200 Wh/kg or higher for high-temperature sodium-sulfur cells, and 150 to 240 Wh/kg for room-temperature sodium-sulfur cells.
  compare: Sodium is a liquid-metal coolant and a battery anode, so its useful figures are the heat transfer, the liquid range and the energy per gram. As an anode its theoretical 1166 mAh/g is the figure to compare against other anodes, and as a coolant its liquid range sets the operating window. Its density (0.968 g/cm3 at 20 C) means it floats on water, and the same chemistry that makes it useful as a coolant makes any water contact dangerous.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Electrical resistivity
      benchmark: electrical_resistivity
  handling:
    - Store dry, well closed and under mineral oil, separate from water.
    - Do not use water or foam on a sodium fire. Use dry sand, dry chemical, soda ash or lime.
    - Sodium vapor and fumes are caustic. For spills, the PubChem safety record calls for a chemical protection suit with self-contained breathing apparatus and evacuation of the danger area.
    - Transport as UN1428, Division 4.3, packing group I.
  good_for:
    - Heat transfer in a liquid metal at high temperature and low pressure, as in a fast-reactor coolant loop.
    - High-temperature sodium-sulfur cells, which run above 300 C and deliver 200 Wh/kg or higher according to the review.
  watch_out:
    - 'Water: it reacts violently, releasing flammable hydrogen and caustic soda.'
    - 'Moist air: it may ignite spontaneously, and vapor ignites at room temperature.'
    - 'Fire fighting: water, foam and carbon dioxide are the wrong agents on a sodium fire.'
  verdict: Sodium is a proven liquid-metal coolant and a proven hot battery anode. It is hazardous to handle in water or moist air, and its fire behaviour, not its energy, is the design problem.
  risk_groups:
    - title: For people
      level: 4
      verdict: Classified Danger, water-reactive and corrosive
      lead: Sodium is classified Danger. It reacts with water, releasing flammable gas, and it causes severe skin burns and eye damage.
      points:
        - label: Hazard classification
          line: In contact with water it releases flammable gases that may ignite spontaneously (H260, 100% of ECHA notifications). It causes severe skin burns and eye damage (H314, 100%). Serious eye damage (H318) is notified in 45.1% of reports.
        - label: Fumes
          line: Vapors and fumes from sodium are strongly alkaline and highly irritating and corrosive to the respiratory tract, eyes and skin.
        - label: Burning sodium
          line: Above 115 C in air, sodium may ignite and produce a sodium peroxide fume, which is strongly alkaline.
    - title: Fire and reactions
      level: 4
      verdict: Sodium fires need dry agents
      lead: The fire behaviour of sodium is the main design problem for reactors and handling.
      points:
        - label: Fire agents
          line: Water and foam produce hydrogen and are wrong on a sodium fire. Carbon dioxide mixed with hot sodium is impact-sensitive and can explode. The ERG guide calls for dry chemical, soda ash, lime or sand.
        - label: Reactor pool
          line: The 2022 study states that sodium pool fire design is the basis of accidents in sodium-cooled fast reactors.
        - label: Halogens and acids
          line: Sodium reacts exothermally with halogens, acids and halogenated hydrocarbons.
    - title: Storage and handling
      level: 3
      verdict: Dry, closed, under mineral oil
      lead: Sodium is kept dry and closed, under mineral oil, away from water.
      points:
        - label: Storage
          line: The PubChem safety record says fireproof, dry, well closed and kept under mineral oil, in a cool, dry, well-ventilated place separate from water.
        - label: Spills
          line: Absorb the spilled sodium dry, then cover the remainder with kerosene, paraffin oil or dry sand.