Antares Nuclear
Builds sodium heat-pipe microreactors for military bases, space and remote grids. Its Mark-0 was the first reactor to go critical under the DOE Reactor Pilot Program.
Facts
Source per value- DesignThe company's lead reactor design name(s) as the company or its regulator names them; semicolon-separated when it markets more than one.
- Mark-0 (test); R1 13
- TypeReactor coolant/technology family. Gas-cooled fast is separated from thermal HTGR designs; sodium-cooled includes both fast and thermal-spectrum designs.
- Heat pipe 2
- Size classDerived from published electric output per module: Micro is 20 MWe or less, Small is above 20 and up to 300 MWe, Medium is above 300 MWe. Legacy heat-only classifications use one third of thermal output as an explicit comparison convention, not a claimed electric rating.
- Micro 2
- MWe / module MWeNet (or gross where only gross is published) electric output of one reactor module as the company or its regulator publishes it. Null for heat-only designs.
- Not published
- MWt / module MWtThermal output of one reactor module as published by the company or its regulator.
- Not published
- FuelFuel form and enrichment class as published (for example LEU UO2, HALEU TRISO, fuel salt).
- HALEU TRISO 2
- Licensing stageFurthest licensing milestone reached with any national regulator: Operating; Construction licensed (construction permit or licence issued); DOE test authorization (a test reactor authorized or built under the US Department of Energy, for example the Reactor Pilot Program or the DOME test bed); Construction under review (construction, site or creation application filed); Design approved (design certification, standard design approval or GDA completed); Design review (formal design review under way, such as UK GDA, CNSC vendor design review or a French safety-options review); Pre-licensing (pre-application engagement only).
- DOE test authorization 1
- RegulatorsNational regulators the company has formally engaged (NRC, CNSC, ONR, ASN, and others), semicolon-separated.
- DOE 1
- Licensing detailThe milestones behind the licensing stage, by regulator, with dates.
- Mark-0 reached zero-power criticality at Idaho National Laboratory on 2026-06-04, the first fueled criticality under the DOE Reactor Pilot Program. 1
- Latest milestoneDate of the milestone that sets the licensing stage (for example the day a construction permit was issued or an application docketed).
- 2026-06-04 1
- First siteLocation of the first-of-a-kind commercial or demonstration unit, with the owner or host.
- Idaho National Laboratory (Mark-0); military installations from 2028 12
- First powerYear the company or its host utility targets for first operation (criticality or commercial operation, as stated) of the first unit. A plan, not a guarantee.
- 2,027 3
- OwnershipPublic (listed shares), Private (venture or privately held), Subsidiary (a unit or joint venture of a larger company) or State-owned.
- Private 3
- TickerExchange and ticker of the company or its listed parent.
- Not published
- ListedFirst trading day of the company's shares (or its listed parent's current ticker) on the exchange named in Ticker.
- Not published
- FundingHeadline funding: equity raised, public listing, government cost-share awards (DOE ARDP, GAIN, Great British Nuclear and others), with amounts and dates.
- $96 million Series B (December 2025); raised a further $470 million in 2026 to build reactors for military bases. 34
- Data-center dealTrue when the company has a signed, announced agreement (PPA, framework, MOU, investment or capacity reservation) with a hyperscaler or data-center operator.
- Not published
- Data-center partnersHyperscalers and data-center operators the company has a signed or announced agreement with, semicolon-separated.
- Not published
- Data-center dealsWhat each data-center or hyperscaler agreement covers: partner, type of agreement, capacity and date.
- Not published
- HQCountry of the company's headquarters.
- United States 1
- RegionHeadquarters region.
- North America 1
Sources
- DOE: first advanced reactor criticality accessed 2026-11-11
- US Army: Antares zero-power criticality accessed 2026-11-11
- Antares achieves initial criticality of Mark-0 accessed 2026-11-11
- NucNet: Antares raises $470 million accessed 2026-11-11
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