Radiant
Unicorn Β· $1.8BFounded 2020 Β· 28 known investors
Radiant Nuclear develops Kaleidos, a portable nuclear microreactor designed to replace diesel generators for remote locations and provide resilient backup power to hospitals, datacenters, and military installations.
Also known as Radiant Industries Β· Radiant Nuclear
Founders & leadership
Investors Β· 28
Also in the syndicate Β· 6
Funding
SEC filings, press & company announcements$300M disclosed across 1 of 3 rounds Β· 2025
- $300MraisedDec 2025 Β· 3 sources
Boost VC (lead), Draper Associates (lead), ARK Venture Fund, Chevron Technology Ventures, Founders Fund
Source β - Undisclosed amountSeries DDec 2025 Β· 3 sources
Boost VC (lead), Draper Associates (lead), Align Ventures, Andreessen Horowitz, ARK Venture Fund, Chevron Technology Ventures, DCVC, Founders Fund, Friends & Family Capital, Washington Harbour Partners
Source β
Source: company announcements and press reports β follow each round's link for the claim.
Valuation Β· disclosed
Disclosed eventsSource: SEC prospectus filings, and round valuations the company or its investors disclosed β follow each entry's link for the claim.
Company profile
researched Aug 2026Radiant (Radiant Nuclear) is a nuclear energy company based in El Segundo, California, founded in 2020, that is developing Kaleidos, a 1 MW electric portable nuclear microreactor intended as a replacement for diesel generators. The unit packages a reactor, shielding, turbomachinery and cooling equipment into a transportable container that can be moved by truck on highway routes or by aircraft, and the container can be separated into sections for transport and maintenance. Radiant states the design requires no site excavation and can reach full power the day after being lowered from the truck.
Kaleidos uses TRISO fuel (ceramic-coated uranium particles) and helium as the heat transfer gas, with an air jacket that cools the core passively by natural convection and no on-site water requirement, relying on fans for air cooling. Alongside 1 MW of electricity, the company says the unit can supply 1.9 MW of thermal power for facility heating or water desalination, and that its turbomachinery operates efficiently between 30% and 100% of rated power to support microgrids. Fuel is depleted after five or more years of operation, after which the container is returned to the factory; Radiant states a unit can be refueled a total of four times for a 20-year product lifetime, leaving no nuclear waste or infrastructure on site. Fleet operations are supported by a centralized 24/7 monitoring system that streams data from deployed units.
Radiant's first reactor is the Kaleidos Demonstration/Development Unit (KDU), to be tested at Idaho National Laboratory's Demonstration of Microreactor Experiments (DOME) facility, with testing targeted for summer 2026; the company describes this as the first new commercial reactor design to achieve a fueled test in over 50 years. Initial customer deployments are planned for 2028. The company is also developing an R-50 production factory in Oak Ridge, Tennessee, sized to produce up to 50 microreactors per year.
Business model
Radiant sells power and hardware to commercial and defense customers, offering purchase either through Power Purchase Agreements (PPAs) or direct unit sales, with factory assembly, fueling and testing of units before deployment and return of containers to the factory for refueling. The company plans mass manufacturing at a dedicated factory rather than bespoke on-site construction.
Direct sales of Kaleidos units and Power Purchase Agreements; reservations/deposits have been taken (for example, deposits accompanying a 20-reactor order).
Traction
Reported milestones include selection by DOE for HALEU fuel allocations (including a second allocation in July 2026), a first DOE HALEU supply contract, a binding commercial HALEU enrichment contract with Urenco, an agreement with the Defense Innovation Unit and the Department of the Air Force for a microreactor at a U.S. military base, a 20-reactor deal with deposits from Equinix, receipt of the first TRISO fuel shipment at INL's DOME facility in July 2026, shipment of the Kaleidos reactor to DOME in August 2026, a TRISO supply agreement with Standard Nuclear through the early 2030s, and NRC acceptance of an accelerated review of a 10 CFR Part 70 license for the R50 production facility in Tennessee. Cumulative venture funding reached $225 million after the Series C and more than $525 million implied following the December 2025 round.
Latest developments
In August 2026 Radiant announced a TRISO fuel supply agreement with Standard Nuclear covering planned Kaleidos deployments through the early 2030s, and said its reactor had departed for Idaho National Laboratory's DOME facility. In July 2026 the DOE selected Radiant for a second HALEU allocation to support the first commercial microreactor at a U.S. military installation, and Radiant received its first TRISO fuel shipment at DOME, ahead of a five-phase testing program targeting more than 150 hours at full power without operator intervention. In May 2026 the NRC launched an accelerated review of Radiant's 10 CFR Part 70 license for its R50 production facility in Tennessee.
βΈFull profile β market position, technology, go-to-market, geography, history, risks & controversies
Market position
Radiant positions itself as a pioneer in mass-produced portable nuclear microreactors and was one of five U.S. companies selected by DOE to receive HALEU fuel, one of 11 companies in the federal Nuclear Reactor Pilot Program, and the first new U.S. reactor design slated to be tested at INL's DOME facility. Press coverage places it among a group of well-funded nuclear startups raising nine-figure rounds amid data-center-driven power demand, and reported a valuation of more than $1.8 billion in December 2025.
Radiant emphasizes factory mass production of a standardized, containerized reactor rather than site-built plants; zero on-site water use through air cooling; passive natural-convection core cooling intended to simplify regulatory approval; helium coolant that does not become radioactive; meltdown-resistant TRISO fuel; deployment without excavation and full power the day after delivery; more than 110 times the energy density of existing diesel systems; and removal of the entire unit at end of fuel life so no waste remains on site.
Technology
Helium-cooled microreactor using TRISO ceramic-coated uranium fuel, rated at 1 MW electric and 1.9 MW thermal, with high-speed turbomachinery efficient from 30% to 100% power. Helium does not become radioactive, and a passive air jacket cools the core by natural convection; no on-site water is required. The design is containerized for road or air transport, factory-fueled and tested, refuelable four times over a stated 20-year lifetime, and monitored remotely through a centralized fleet-monitoring system. Fuel is high-assay low-enriched uranium (HALEU) sourced under DOE allocations and commercial enrichment contracts.
Go-to-market
Radiant markets reservations directly via its website and pursues government and enterprise channels: a Department of Defense agreement with the Defense Innovation Unit and the Department of the Air Force for a microreactor on a U.S. military base, participation in DOE programs (HALEU allocations, DOME testing, the President's Nuclear Reactor Pilot Program), and commercial contracts such as a 20-unit agreement with Equinix.
Military installations and defense users, data centers and digital infrastructure operators, hospitals and disaster/emergency response, remote villages and remote industry, and other critical infrastructure requiring resilient off-grid or backup power.
Geography
Headquartered in El Segundo, California. Demonstration reactor testing at Idaho National Laboratory's DOME facility in Idaho; planned R-50 production factory in Oak Ridge, Tennessee. Commercial activity includes a HALEU enrichment contract with Urenco signed at the U.S. embassy in London.
History
Radiant was founded in 2020 and is based in El Segundo, California. By August 2022 it described its goal as bringing one of the world's first factory-constructed microreactors to market with the Kaleidos 1 MW unit. In May 2025 it published its "Atoms For Prosperity" master plan and closed a $165 million Series C, bringing total venture funding to $225 million, following DOE selection as one of five companies to receive HALEU fuel. In December 2025 it raised more than $300 million led by Draper Associates and Boost VC ahead of breaking ground on its Oak Ridge, Tennessee factory. Through 2026 it progressed toward its first reactor test: NRC accelerated review of its Tennessee production facility license (May 2026), first TRISO fuel shipment received at INL's DOME facility (July 2026), a second DOE HALEU allocation (July 2026), shipment of the reactor to DOME (August 2026), and a TRISO fuel supply agreement with Standard Nuclear (August 2026).
Risks & controversies
TechCrunch coverage notes the wave of nine-figure nuclear fundraises tied to data-center power demand and raises the question of a sector bubble, suggesting a possible winnowing if startups fail to deliver on first-reactor milestones; it also notes that reaching criticality on a first-of-a-kind unit does not guarantee successful replication at manufacturing scale. Radiant's own writing describes regulatory barriers on materials, prescriptive rules and rigid timelines as obstacles for reactor developers.
Compiled by commissioned research from 8 cited public sources β announcements, filings, and press listed under research sources below.
Key figures
latest reportedCompany-reported or press-reported figures, each dated to when it was claimed β not independently audited.
Competitors Β· 6
by search overlap
Companies competing with Radiant for the same Google search keywords, organic and paid, via search-intersection analysis.
Non-dilutive funding Β· 4 SBIR/STTR awards
Federal grants β no equity taken| Agency | Phase | Year | Amount |
|---|---|---|---|
| U.S. Air ForceAir Force | Phase II | 2023 | $1.2M |
| Department of Energy | Phase IISTTR | 2023 | $1.1M |
| Department of Energy | Phase I | 2022 | $199.2K |
| U.S. Air ForceAir Force | Phase I | 2021 | $45.3K |
Source: SBIR.gov award data (U.S. Small Business Administration). SBIR/STTR awards are competitive federal R&D grants and contracts β non-dilutive capital alongside any venture rounds above.
Timeline Β· 14
launches, deals, and filingsAgreement secures fuel for planned Kaleidos deployments through the early 2030s as part of an end-to-end supply chain.
Allocation supports the planned first commercial microreactor at a U.S. military installation.
Receipt of fuel clears the path to full-power, full-temperature testing under a five-phase program targeting more than 150 hours at full power without operator intervention.
Nuclear Regulatory Commission begins accelerated review of Radiant's 10 CFR Part 70 license application for its R50 production facility in Tennessee.
Round valuing the company at more than $1.8 billion supports commercialization scaling and groundbreaking on the R-50 factory in Oak Ridge, Tennessee.
$300M source β
Deal with deposits signed with data center developer Equinix for 20 reactors.
Series C brings total venture funding to $225 million; proceeds primarily fund completion of the Kaleidos Development Unit and factory siting and early construction.
$165M source β
Radiant selected by the U.S. Department of Energy as one of five U.S. companies to receive high-assay low-enriched uranium for the first Kaleidos test at INL's DOME facility.
Dr. Rita Baranwal, former Assistant Secretary for Nuclear Energy, joined as Chief Nuclear Officer; Dr. Mike Starrett joined as Chief Revenue Officer; nearly a dozen VP and Director hires across engineering, manufacturing and supply chain.
Described as the first deal for mass-manufactured nuclear microreactors on a U.S. military base.
Described as the first binding commercial contract by a U.S. advanced reactor developer for Western commercial HALEU enrichment services; signed at the U.S. embassy in London.
One of 11 companies selected for a federal program that speeds approval timelines rather than providing grants or loans.
Dated company events from announcements, filings, and press; legal rows summarize public dockets and regulator releases.
In the news
βΈResearch sources Β· 8
primary sources listed
- Radiantradiantnuclear.com Β· web
8 public sources were cited for this profile; the first-party ones are listed here.
Frequently asked questions
- What does Radiant do?
- Radiant builds Kaleidos, a factory-produced 1 MW portable nuclear microreactor intended to replace diesel generators.
- Who are Radiant's investors?
- Radiant's investors include Acequia Capital (AceCap), Andreessen Horowitz, Beyond Capital, Cantos Ventures, Carbon, Crosscut Ventures, DCVC (Data Collective), Decisive Point and 14 more.
- How much funding has Radiant raised?
- Radiant has disclosed $300M raised across 1 of its 3 known rounds.