PrivateFounded 2020🇺🇸1921 E. Maple Ave, El Segundo, CaliforniaCEO Doug Bernauer
Radiant is still pre-revenue on Kaleidos sales. A 9 October 2026 deep audit found no public announcement that the Kaleidos Development Unit was installed, fueled, or taken to zero-power criticality at INL DOME after Q3 closed on 30 September.
Latest update Nov 2, 2026
01
The news index still tops out at the 9 September Centrus HALEU contract and the 12 August El Segundo departure. Wikipedia still records the August shipment, not criticality. The NRC Kaleidos page, last reviewed 15 September, remains pre-application; the KDU commissioning plan is under review and the R-50 Part 70 application is in RAI. NRIC says DOME is currently hosting Kaleidos and next availability begins July 2027, while another FAQ line still says testing likely in 2027; neither is a criticality result. No sourced revised campaign date. Janus is up to $750 million for 15 units; Fort Benning remains three 1 MW units with the pad still under evaluation; Buckley remains the 2028 ANPI site.
radiantnuclear.comUpdated Oct 9, 2026
Analysis · 4 min read · Oct 7, 2026The long view on Radiant Nuclear: strategy, technology and what to watch02
Q3 2026
After installation and fueling at INL's DOME, progress through zero-power criticality, 1 MW thermal, full-power/full-temperature operation, and a minimum 150-hour unattended run. Radiant targeted completing that campaign in Q3 2026. As of September 18, 2026 no criticality announcement had been published, so the Q3 window is tight and may slip into Q4.
Q3 2026
Q4 2026
Radiant's regulatory engagement plan says it will submit an operating-license application for Kaleidos at R-50 in Q4 2026, separate from the Part 70 materials license now under review. NRC pre-application (docket 99902106) has been open since October 2022. As of September 18, 2026 no operating-license application was on file.
Dec 18, 2026
The NRC accepted Radiant's 10 CFR Part 70 application for the Oak Ridge fueling building on May 1, 2026 and, in a July 27 Federal Register notice, dated its license determination to December 18, 2026. Radiant has said it is targeting commissioning of R-50 in January 2027. A Part 70 license is for possessing and loading fuel, not a commercial reactor operating license.
2028
ANPI selection on April 22, 2026 names Buckley SFB in Aurora, Colorado as the proposed site, with first Kaleidos reactors targeted for 2028. Siting and NEPA analysis have not finished. Radiant frames this as America's first commercially developed microreactor at a military installation.
2030
The August 26, 2026 Janus agreement is for 15 Kaleidos units totaling up to $750M, with Fort Benning named and deployments framed through 2030. Payments are milestone-based. The actual pad location at Benning is still to-be-determined.
03
Radiant said on October 29, 2026 that the Department of Energy approved the Documented Safety Analysis for its Kaleidos microreactor, covering operation at power as well as initial criticality. The company said a Readiness Review still has to be completed before fueling and a five-phase test at Idaho National Laboratory, which it describes as 60 effective full-power days and at least 150 hours of continuous full-power operation without an operator. The release does not say the reactor has been fueled or taken critical, and no separate DOE approval document was opened.
04
A 1 MWe portable high-temperature gas-cooled microreactor using TRISO fuel, helium coolant, and prismatic graphite blocks with zirconium-hydride moderator, packaged in a single shipping container with power conversion and air cooling. Designed to be trucked, shipped, or flown to a prepared pad, reach full power the next day, run five years before factory refueling, and last 20 years (four cores). No on-site water and no on-site spent-fuel storage.
The first full-scale Kaleidos article, the same design, size, and commercial fuel load intended for customers, built in El Segundo and shipped by trailer to INL's DOME facility for a five-phase campaign: install and fuel, zero-power criticality, 1 MW thermal, full-temperature/full-power operation, and a minimum 150-hour unattended run.
05
Wikipedia infobox still says 100 (2025). TrueUp still prints a Live Data estimate of 200 and a separate line of 190.
Janus is a milestone-based development-and-deployment contract up to $750M, not current product revenue
~$516M+ disclosed equity through the December 2025 Series D, plus an undisclosed Lockheed Martin Ventures add-on in February 2026; Wikipedia and the Los Angeles Business Journal put the 2026 total over $575M
300,000 sq ft / ~80-acre Oak Ridge campus, targeting 50 reactors per year; Part 70 review due December 18, 2026
No public install, fueling, or zero-power criticality as of 2 Oct 2026; Q3 target closed without a sourced revised date
06
Operating status
DSA approved; Kaleidos not fueled
On October 29, 2026 Radiant said DOE approved the Kaleidos Documented Safety Analysis and that fueling follows a Readiness Review. The same release plans 60 effective full-power days over several months and, as a separate capstone, at least 150 continuous full-power hours without an operator. Those are different measures, and neither is a result. No DOE or INL approval document was found. Radiant has not announced installation, fueling, or zero-power criticality, and it has not published a calendar date replacing the Q3 2026 campaign target. The NRC Kaleidos page, last reviewed October 21, 2026, still shows pre-application work and lists the KDU commissioning plan as under review. No operating-license application is listed. The R-50 Part 70 application remains under review. On October 20, 2026 the Navy selected Radiant to design, build, and deliver one prototype Kaleidos power plant at Naval Weapons Station Crane. The Navy says that selection sits inside the existing August 26 Janus award and states no price, unit count, or operating date.
Military microreactor deployments (contracted / planned)
Up to $750M Janus agreement with the Army and DIU for 15 Kaleidos units, with Fort Benning as the named site and deployments framed through 2030. Separate ANPI selection to develop and operate reactors at Buckley Space Force Base, with first deliveries targeted for 2028. Both are development-and-deployment programs, not yet operating plants.
Commercial Kaleidos sales (planned)
Factory-built 1 MWe portable reactors sold or contracted to data centers, remote industry, hospitals, and off-grid sites. Equinix has a deposit-backed agreement for 20 units. Radiant says it will fuel, refuel, and store spent fuel at its own facilities so customer sites never hold spent fuel.
Exclusive year-long access to INL's DOME test bed for a full-scale, full-power Kaleidos campaign, plus a second DOE HALEU allocation announced July 23, 2026 and selection for the Nuclear Energy Launch Pad.
07
2026
Navy selects a Crane prototype inside the Janus award
On October 20, 2026 the Department of the Navy said it selected Radiant to design, build, and deliver a prototype Kaleidos microreactor power plant at Naval Weapons Station Crane, Indiana. The Navy says the selection is not a new or additional Janus effort and is accounted for in the August 26, 2026 award. The page gives no price, no reactor count, and no operating date. Next steps it names are environmental review, site design, and regulatory coordination.
DOE approves the Kaleidos safety analysis
On October 29, 2026 Radiant said DOE approved the Kaleidos Documented Safety Analysis. The approval covers powered operation as well as initial criticality and is the gate before a Readiness Review, fueling, and a five-phase test. It is not a start of nuclear operations. Radiant distinguishes it from the February 9 preliminary approval.
RAFT ATR fuel test prepared in parallel with DOME
Idaho National Laboratory, writing in ANS Nuclear Newswire on September 18, 2026, said Radiant is preparing the Radiant ATR Fuel Test (RAFT) in the Advanced Test Reactor using HALEU TRISO fabricated by Standard Nuclear. RAFT is meant to qualify Kaleidos fuel to higher burnup than the DOME campaign can provide, because that demonstration is scheduled to last months rather than years. The same article still described DOME reactor tests as upcoming and captioned TRISO fuel as delivered for those upcoming tests, which is not a criticality or later-phase result.
Locks TRISO through the early 2030s; Centrus HALEU contract
On August 20, 2026 Radiant signs a long-term TRISO fabrication agreement with Standard Nuclear through the early 2030s. On September 9 it signs a definitive multi-year HALEU supply contract with Centrus, with deliveries before the end of the decade and prepayments to support Piketon expansion, adding a U.S.-origin unobligated enrichment path for national-security deployments.
$750M Army Janus award for 15 Kaleidos units
On August 26, 2026 the Army and DIU execute a binding agreement totaling up to $750M for Radiant to develop and deploy 15 Kaleidos reactors under Janus - Radiant says it is the largest award in the program and one of DIU's largest contracts. The named site is Fort Benning, Georgia; deployments are framed through 2030. The Army's broader Janus awards total up to $2.2B across five vendors.
TRISO fuel arrives at DOME; Kaleidos shipped to Idaho
On July 1, 2026 Standard Nuclear-fabricated TRISO fuel arrives at INL's DOME facility. On August 12 the Kaleidos Development Unit leaves El Segundo on a trailer for the more than 1,000-mile road trip to DOME, where Radiant plans a five-phase campaign through zero-power criticality, 1 MW thermal, full power, and a 150-hour unattended run.
NRC accepts R-50 Part 70 application
On May 1, 2026 the NRC accepts Radiant's 10 CFR Part 70 special-nuclear-material license application for the Oak Ridge R-50 fueling building for detailed review, aiming to finish about 55% faster than the standard schedule. A Federal Register notice later dates the staff's license determination to December 18, 2026.
Buckley Space Force Base selected under ANPI
On April 22, 2026 the Department of the Air Force and DIU select Radiant to develop and operate Kaleidos reactors proposed for Buckley Space Force Base in Aurora, Colorado, with first deliveries targeted for 2028. Next steps include NEPA siting and environmental analysis.
2026
DOE PDSA-equivalent approval; Lockheed Martin Ventures invests
On February 9, 2026 DOE approves Radiant's DOE Authorization Request for Kaleidos, meeting the intent of a Preliminary Documented Safety Analysis for a full-power DOME test. On February 17 Lockheed Martin Ventures joins the oversubscribed round as a strategic investor (amount undisclosed).
2025
$300M+ Series D at $1.8B valuation; Equinix orders 20 units
On December 17, 2025 Radiant raises more than $300M led by Draper Associates and Boost VC, with Founders Fund, ARK Venture Fund, Chevron Technology Ventures, and others, at a valuation of more than $1.8B. The company says Equinix has signed a deposit-backed deal for 20 Kaleidos reactors.
R-50 factory sited in Oak Ridge after leaving Wyoming
After dropping a Bar Nunn, Wyoming factory plan over spent-fuel storage politics, Radiant announces on October 13, 2025 that it will build R-50 on former K-27/K-29 Manhattan Project land in Oak Ridge, Tennessee, a ~$280M investment aiming at 50 Kaleidos units a year after 2028 production starts.
First DOME test slot; first DIU/Air Force microreactor deal
On July 2, 2025 DOE selects Radiant as the first new reactor design to be tested in DOME. On August 8 it signs what it calls the first agreement designed to deliver a mass-manufactured nuclear microreactor to a U.S. military base, with DIU and the Department of the Air Force under ANPI.
Series C closes at $165M; Rita Baranwal joins as CNO
Radiant announces a $100M Series C in November 2024 led by DCVC and closes the round at $165M on May 28, 2025 with Giant Ventures, StepStone, ARK Venture Fund, and others, taking disclosed venture funding to about $225M. In June it hires former Assistant Secretary for Nuclear Energy Rita Baranwal as chief nuclear officer.
2023
2020
08
$516Mdisclosed across 6 rounds with a stated amount
Cumulative disclosed raise · dated rounds
Angel
September 2020
Hank Vigil, Josh Manchester, Thomas McInerney, Charlie Songhurst, other angels
Series A
March 2022
$10M (company figure; Not Boring later described the round as $11M)
Union Square Ventures (lead), Boost VC, Cantos Ventures, Tribe Capital, Decisive Point, McKinley Capital, JAM Fund, Nucleation Capital, Also Capital, DCVC
Series B
April 2023
Andreessen Horowitz (lead), Founders Fund, Decisive Point, McKinley Capital, Draper, Cantos Ventures, Boost VC
Series C
November 2024
DCVC (lead, Rachel Slaybaugh), Andreessen Horowitz, Union Square Ventures, Felicis, Washington Harbour Partners, Chevron Technology Ventures, Founders Fund, Decisive Point, McKinley Alaska, Boost VC, Also Capital
Series C extension
May 2025
$65M, taking Series C to $165M and total venture funding to $225M
DCVC, Giant Ventures, StepStone, ARK Venture Fund, Align Ventures, Crossbeam Venture Partners, Gigascale Capital, HartBeat Ventures, Pax Ventures, SGA Capital, others
Series D
December 2025
Draper Associates (co-lead), Boost VC (co-lead), Founders Fund, ARK Venture Fund, Chevron Technology Ventures, Friends & Family Capital, others
Series D add-on
February 2026
Lockheed Martin Ventures (strategic)
