Oklo

🇺🇸 Santa Clara, US · Founded 2013 · Active

Oklo is a US nuclear company based in Santa Clara, California, founded in 2013 and listed on the New York Stock Exchange since May 2024 through a merger with AltC Acquisition Corp. It is developing the Aurora powerhouse, a sodium-cooled fast reactor using metal fuel, modelled on the Experimental Breeder Reactor II, and plans to own the plants and sell their power rather than sell reactors. An earlier 1.5 MWe version of Aurora was the subject of a combined licence application that the Nuclear Regulatory Commission denied in January 2022 for lack of information; Oklo has since worked with the NRC in pre-application. The company began pre-construction work on its first Aurora at Idaho National Laboratory in 2025 and says it aims to start commercial operation by 2028. No Aurora reactor has been built.

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Sector: Fission
Technology: Sodium fast reactor
Fuel: High-assay low-enriched uranium
Role: Reactor developer

It is the operator of record for Aurora-INL (planned) and Groves Isotope Test Reactor (operating).

Its recorded equity, $3.4bn, is the 2nd largest of the 25 organisations with a priced round here. Not every round is on record, so this is not its total raised.

6 regulatory milestones are tracked here, 2 of them anchored to a docket reference in the regulator's own record.

Terms

Sodium fast reactor: Liquid sodium coolant with a fast, unmoderated neutron spectrum. Sodium carries heat superbly at atmospheric pressure, but burns in air and reacts violently with water. Large sodium-cooled cores can have a positive sodium void effect that the core design must offset. Fuel is typically metal alloy or mixed-oxide.
High-assay low-enriched uranium: High-assay low-enriched uranium: uranium enriched to between 5% and just under 20% uranium-235, as the US Department of Energy defines it. It is still formally low-enriched, because the international line for highly enriched uranium is 20%, which is why many designs specify 19.75%. The binding supply constraint for many advanced reactor designs. The 5 to 10% part, which carries lighter US physical-security requirements than material from 10% up, is also tagged as LEU+. A developer calling fuel in that band 'LEU' is making a labelling choice, not describing a different enrichment.

Funding

$3.4bn

equity in the 5 rounds recorded here, incl. $276m via SPAC

2026-05-13
Equity round
At-the-market equity programme of up to $1.0 billion opened 13 May 2026 and terminated 10 September 2026 after selling 17,971,448 shares for about $1.0 billion gross. Recorded at $670.0 million, the net proceeds reported to 30 June 2026 (10,712,054 shares), as a minimum: net proceeds for the July to September sales are not yet reported.
$670m
2025-12-04
Equity round
At-the-market equity programme of up to $1.5 billion opened 4 December 2025 and closed 28 January 2026. Net proceeds $1,476.2 million: $294.3 million from December 2025 sales and $1,181.9 million from January 2026 sales. Gross $1,499.9 million.
$1.5bn
2025-06-12
Equity round
Underwritten public offering of 7,666,667 shares at $60.00, closed 16 June 2025: $460.0 million gross, $440.1 million net after $18.4 million underwriting and $1.5 million other costs.
$440m
2025-06-02
Equity round
At-the-market equity sales under a 2 June 2025 sales agreement: 7,384,019 shares sold 2 August to 3 September 2025 for $540.0 million gross and $526.1 million net.
$526m
2024-05
SPAC merger
Listing via business combination with AltC Acquisition Corp, closed 9 May 2024 (NYSE: OKLO from 10 May). The 10-Q reports $276.2 million received at close, against a "$306 million" headline in the 7 May release. No PIPE is identified in the filing.
$276m

Designs

Design	Developer	Approach	Electrical output per unit	Size class	Licensing stage
Aurora powerhouse Aurora	Oklo	Sodium fast reactor	15 to 75 MWe planned	Small modular reactor	Application denied for one plant: NRC denies Aurora combined licence application · US Nuclear Regulatory Commission · 2022-01-06

Devices

Aurora-INLSFRPlannedNo figures yet Groves Isotope Test ReactorOperatingNo figures yet

Licensing

2020-03-11achieved
Application submitted
Aurora custom combined licence application submitted (Idaho National Laboratory) · US Nuclear Regulatory Commission
Docket 52-049 · ADAMS ML20075A001
2027retracted
First criticality
Aurora first criticality · US Nuclear Regulatory Commission
Seed placeholder created to exercise the pipeline, never sourced. Its target dates were illustrative, and a reader on /licensing/ could not distinguish it from a sourced milestone. Retracted rather than deleted so the record of having published it survives.
No public anchor for this stage
2026-08-05claimed
First criticality
Groves Isotope Test Reactor first criticality (Oklo-reported)
Operator-reported. Under DOE authorisation, not NRC licensing; no regulator document or reference number was available. Oklo also calls it the first reactor under the DOE pilot programme to reach criticality on private land; that comparative claim is not recorded as fact.
No public anchor for this stage
2022-01-06achieved
Application denied
NRC denies Aurora combined licence application · US Nuclear Regulatory Commission
Docket 52-049 · ADAMS ML21357A034 (denial letter)
2026-06claimed
Aurora-INL: DOE approves Preliminary Documented Safety Analysis (Oklo-reported)
No regulatory stage recorded · United States Department of Energy
No stage and no regulator: this is a DOE authorisation step (the second of five, per Oklo), not an NRC licensing stage, and the dataset has no DOE organisation record. No docket or DOE document number is available, so the milestone is unverifiable from outside and rests on the developer's own report.
No public anchor for this stage
2026-07-23claimed
Groves Isotope Test Reactor: DOE startup authorisation (Oklo-reported)
No regulatory stage recorded · United States Department of Energy
No stage and no regulator: a DOE Reactor Pilot Program authorisation, not an NRC operating licence. No reference number is public in any source opened; unverifiable from outside.
No public anchor for this stage

Related companies

Sources

Oklo Inc. - Homeoperator
Oklo Inc.aggregator
AltC Acquisition Corp. / Oklo (SEC exhibit)operator