Radiant
Kaleidos — Earth's first mass-produced portable nuclear microreactor
Energy / Climate
📍 El Segundo, CA
Founded 2019
Current Valuation
$1.8B
as of 2025-Q4
UNICORN
Radiant, founded in 2019 by former SpaceX engineer Doug Bernauer and based in El Segundo, California, is building the Kaleidos — a 1MWe portable nuclear microreactor designed to be mass-produced and transported by truck or cargo aircraft, aimed at replacing diesel generators for remote sites, disaster zones and defense applications. After a $165M Series C in mid-2025, the company raised over $300M in a December 2025 Series D at a roughly $1.8B valuation, with backing from Founders Fund, a16z's American Dynamism team, Decisive Point and Draper Associates, as it advances its Kaleidos Demonstration Unit toward a planned 2026 startup at Idaho National Laboratory.
Company Profile
Growth
First reactor (Kaleidos Demonstration Unit) targeting startup in 2026
Last Round
Series D — $300M (Dec 2025) · Lead: Founders Fund
Founders & Key People
Doug Bernauer
Investors
Founders Fund · Andreessen Horowitz · Decisive Point · Draper Associates · Union Square Ventures · McKinley Alaska Private Investment · ARK Invest · Nucleation Capital
Products
- Kaleidos 1MWe portable microreactor
- Kaleidos Demonstration Unit (KDU) at Idaho National Laboratory
Competitors
Oklo · X-energy · NuScale Power · Last Energy
EnergyClimate TechNuclearUnicornDeep Tech
Private-company numbers are not real-time. Reflects publicly disclosed valuations from press releases, news reports, and tender offers as of 2025-Q4. Refreshed quarterly.