Table of Contents
⚠ Disclaimer: This entry may be incomplete, out of date, or inaccurate. It is AI-maintained on a best-effort basis. Do not rely on it as a sole source — verify claims independently using the sources listed below.
Summary
NuCube Energy is a microreactor startup co-founded in 2023 at Idealab Studio by serial entrepreneur Bill Gross and nuclear engineer Dr. Cristian Rabiti (CEO), developing a high-temperature, TRISO-fueled, heat-pipe-cooled microreactor pitched as having no moving parts and delivering industrial heat up to 1,100°C alongside electricity. The company is the smallest and least funded of DOE’s first four Nuclear Energy Launch Pad selections, having raised $13 million in a February 2026 round led by Arizona Nuclear Ventures. Unlike Deployable Energy and Radiant Industries, which test at Idaho National Laboratory under the Launch Pad INL pathway, NuCube was selected under the Launch Pad USA pathway together with Idaho State University to deploy its Advanced Research and Test (ART) Reactor on ISU’s Pocatello, Idaho campus, where it will serve as both an operator-training platform and a commercialization testbed. NuCube is separately validating autonomous operation and remote monitoring with Argonne National Laboratory through a DOE GAIN voucher, and opened a Phoenix, Arizona office in May 2026 to pursue the state’s data center and industrial power demand growth.
Key Facts
- Founded: 2023, at Idealab Studio
- HQ: Reported as Pasadena, CA (130 W. Union Street — Idealab Studio’s address, per NuCube’s own website) and separately as Idaho Falls, ID (per DOE Launch Pad coverage); the company also opened a Phoenix, AZ office in May 2026 — see Claim Verification for the location discrepancy
- Type: Private
- Co-Founder: Bill Gross (Idealab Studio founder)
- Co-Founder & CEO: Dr. Cristian Rabiti
- Chief Legal Officer: Michael Green (appointed May 2026)
- Reactor technology: High-temperature, solid-state, heat-pipe-cooled microreactor; TRISO fuel; described by the company as having no moving parts
- Operating temperature: Up to 1,100°C (industrial process heat plus electricity)
- Power rating: Reported inconsistently across sources — 15 MW (thermal, per one Launch Pad summary) vs. “4-MWth microreactor platform” specifically for the ART Reactor deployed at Idaho State University (per BusinessWire) — see Claim Verification
- Funding: $13 million raised February 19, 2026, led by Arizona Nuclear Ventures, with Emission Reduction Corporation (led by Marin Katusa), Rob Walton, and Jordan Rose Walton participating
- DOE Nuclear Energy Launch Pad USA: Selected April 28, 2026, jointly with Idaho State University, to deploy the Advanced Research and Test (ART) Reactor on ISU’s Pocatello campus for operator training, academic research, and commercialization support
- DOE GAIN voucher: FY2026 voucher with Argonne National Laboratory to validate autonomous operation and remote monitoring systems for the NuCube microreactor (announced April 2026)
- Arizona expansion: Opened Phoenix office May 4, 2026, citing Arizona’s data center, semiconductor, and industrial electricity demand growth; John Schreiber (General Partner, Arizona Nuclear Ventures) sits on NuCube’s board
What It Is / How It Works
Heat-pipe cooling, no moving parts: NuCube’s central engineering claim is a solid-state, heat-pipe-cooled reactor design with no pumps or moving mechanical parts in the primary heat transport path — heat pipes passively conduct thermal energy from the reactor core outward using a sealed working-fluid phase-change cycle, a design approach shared conceptually (though not identically implemented) with other heat-pipe microreactor concepts pursued elsewhere in the advanced reactor industry. The company frames “simplicity” as the core lever for both affordability and safety, arguing that eliminating moving parts and active cooling systems reduces both capital cost and the number of failure modes requiring active mitigation.
TRISO fuel, high-temperature output: Like Radiant Industries and the DOE Launch Pad cohort generally, NuCube uses TRISO particle fuel. The claimed 1,100°C output temperature is well above what light water reactors can deliver and is aimed at industrial process heat customers (chemical processing, hydrogen production, desalination) in addition to electricity generation — a dual heat-and-power pitch distinct from the pure-electricity focus of Deployable Energy’s Unity or Radiant’s Kaleidos.
Launch Pad USA vs. Launch Pad INL: DOE’s Nuclear Energy Launch Pad offers two pathways: Launch Pad INL, for projects tested at Idaho National Laboratory (the pathway used by Deployable Energy and Radiant Industries), and Launch Pad USA, for projects deployed outside INL with DOE regulatory and technical support extended to the chosen site. NuCube and Idaho State University’s ART Reactor deployment on ISU’s Pocatello campus is a Launch Pad USA project — the reactor will sit at a university, not a national laboratory, functioning simultaneously as a commercial technology demonstration and an academic/operator-training resource. This is a notably different institutional model than the other three Launch Pad companies in this section, which all test at INL.
Idealab Studio origin: NuCube was co-founded within Idealab Studio, the incubator arm of Bill Gross’s Idealab — a decades-old Pasadena startup studio with an established (if mixed) record of hardware and energy ventures. This gives NuCube a different institutional lineage than the venture-capital-backed, aerospace-alumni-founded pattern seen at Deployable Energy and Radiant Industries elsewhere in this section.
Notable Developments
- 2026-05-04: Opens Phoenix, AZ office and appoints Michael Green (formerly of Oklo, TerraPower, and Pinnacle West/Arizona Public Service, and a former US Navy nuclear propulsion officer) as Chief Legal Officer, citing Arizona’s data center and industrial power demand growth. (BusinessWire)
- 2026-04-28: Selected with Idaho State University for DOE’s Nuclear Energy Launch Pad USA to deploy the Advanced Research and Test (ART) Reactor on ISU’s Pocatello campus. (BusinessWire)
- 2026-04: Announces DOE GAIN voucher with Argonne National Laboratory to validate autonomous operation and remote monitoring systems, running through FY2026. (BusinessWire)
- 2026-02-19: Raises $13 million led by Arizona Nuclear Ventures, with Emission Reduction Corporation, Rob Walton, and Jordan Rose Walton participating. (GPEC)
- 2023: Co-founded by Bill Gross and Dr. Cristian Rabiti at Idealab Studio.
Key People
Dr. Cristian Rabiti — Co-Founder & CEO
- LinkedIn: linkedin.com/in/cristianrabiti
- Background: Nuclear engineer; leads NuCube’s technology and commercialization strategy; quoted extensively across the company’s DOE Launch Pad and Arizona expansion announcements
Bill Gross — Co-Founder
- LinkedIn: linkedin.com/in/billgrossidealab
- Background: Founder of Idealab, the Pasadena startup studio that has incubated 150+ companies since 1996; serial entrepreneur across energy, internet, and hardware ventures
- Notes: Gross’s role is as studio founder/co-founder rather than day-to-day operator; Rabiti is the operating CEO
Michael Green — Chief Legal Officer
- LinkedIn: linkedin.com/in/michael-green-1344485
- Background: 20+ years of nuclear and energy regulatory legal experience; previously Deputy General Counsel for Strategic Execution at Oklo; senior counsel roles at TerraPower and Pinnacle West Capital Corporation (Arizona Public Service parent, covering Palo Verde Nuclear Generating Station matters); former US Navy officer in the Naval Nuclear Propulsion Program
- Notes: ⚑ Overlap: Green’s prior roles at both Oklo and TerraPower — both documented elsewhere in this research section — mean NuCube’s legal leadership has direct institutional experience at two of its Launch Pad-era competitors’ predecessor programs
John Schreiber — Board Member (Arizona Nuclear Ventures)
- LinkedIn: not found
- Background: General Partner, Arizona Nuclear Ventures (lead investor in NuCube’s $13M round); serves on NuCube’s board
People — Last Reviewed: 2026-08-18
Supply Chain Position
| Layer | Detail |
|---|---|
| Fuel | TRISO particle fuel — same fuel form as Radiant Industries and existing section entries Kairos Power and X-energy; fabricator not disclosed in sources reviewed |
| Cooling | Heat-pipe (passive, solid-state); no separately disclosed fabrication/supply chain partner |
| Deployment site | Idaho State University, Pocatello, ID (Launch Pad USA pathway) — a university campus rather than a national laboratory or commercial industrial site |
| Autonomous operation validation | Argonne National Laboratory (DOE GAIN voucher, FY2026) |
| Regulatory pathway | DOE Launch Pad USA program; no NRC licensing milestone identified in sources reviewed as of last review |
| Target markets (downstream) | Industrial campuses, remote operations, data infrastructure; explicit Arizona market push (data centers, semiconductor manufacturing) following May 2026 Phoenix office opening |
⚑ Smallest-funded Launch Pad company: At $13M raised, NuCube is an order of magnitude behind Radiant Industries (~$525M+) and General Matter ($50M Series A plus a $900M DOE contract) in this section’s Launch Pad cohort, and its DOE support is a GAIN voucher (a smaller, in-kind technical-access award) rather than a large capital contract. Its Launch Pad USA selection — deploying at a university rather than at INL — is also a materially different, lower-cost-per-project model than the INL-based pathway used by Deployable Energy and Radiant. Scale expectations should be calibrated accordingly.
Claim Verification
Claim: NuCube’s reactor platform is variously “15 megawatts” or “4-MWth”
Status: Unresolved discrepancy between sources
Supporting: Both figures come from credible-seeming coverage — the 15 MW figure appears in general Launch Pad selection summaries, while the “4-MWth” figure is specifically attributed to the ART Reactor platform being deployed at Idaho State University, per a BusinessWire press release
Refuting / questioning: No source reviewed in this session directly reconciles the two figures; it is possible NuCube has multiple reactor size classes in its roadmap (a smaller university/demonstration unit and a larger commercial unit), or one figure is simply inaccurate in secondary reporting — this entry cannot resolve the discrepancy from sources fetched to date
Summary: Treat the specific power rating as unverified until a NuCube primary source (company site, SEC/NRC filing, or direct company statement) is fetched and confirmed. Both figures are noted here rather than silently picking one.
Claim: NuCube HQ location
Status: Unresolved discrepancy between sources
Supporting: NuCube’s own website lists a Pasadena, CA address (130 W. Union Street), matching Idealab Studio’s known location
Refuting / questioning: DOE Launch Pad coverage (fetched via a secondary summary, not a primary DOE document in this session) describes NuCube as Idaho Falls-headquartered; the company’s own May 2026 announcement frames Phoenix as a new office, implying Pasadena and/or Idaho Falls as pre-existing locations rather than Phoenix being the primary HQ
Summary: NuCube likely operates from multiple locations (Pasadena as corporate/Idealab-affiliated address, an Idaho Falls presence near Idaho National Laboratory for regulatory/technical engagement, and now Phoenix for commercial development), but this entry cannot confirm which, if any, is the formal legal headquarters without a primary corporate filing.
Sources
- NuCube Energy Raises $13 Million — GPEC
- NuCube Energy and Idaho State University Selected for DOE Nuclear Energy Launch Pad USA — BusinessWire
- NuCube Opens Arizona Office and Appoints Chief Legal Officer — BusinessWire
- NuCube Energy and Argonne to Validate Remote Operations Through FY 2026 GAIN Voucher — BusinessWire
- NuCube Energy — nucube.energy
- DOE selects first companies for nuclear launch pad — ANS Nuclear Newswire
- National Reactor Innovation Center announces first selections for Nuclear Energy Launch Pad — Idaho National Laboratory
See Also
Nuclear section overview: Nuclear Energy Research — deployment status tracker and DOE Reactor Pilot Program / Nuclear Energy Launch Pad context alongside Deployable Energy, General Matter, Radiant Industries, Oklo, X-energy, and Kairos Power.