Radiant Announces $300M+ Series D Raise

Nucleation Capital is pleased to congratulate Radiant Nuclear and share their December 17th announcement of its close of a $300+ Million Series D financing, led by Draper Associates and Boost VC for a combined $100 million check. Many prior Radiant investors are also re-investing including DCVC, Andreessen Horowitz, Founders Fund, Nucleation Capital and others.

Nucleation Capital is participating in this Series D financing, so all current subscribers will gain access to this investment, which marks Nucleation's third investment into Radiant since the company raised its Series A in 2021. Additionally, this will be the first time that Nucleation has invested three times into a venture, which is a reflection of the company's impressive success knocking down milestones towards the design, development, construction, testing and licensing of Kaleidos, the company's 1 MW transportable power generator.

Radiant is among a small handful of advanced nuclear developers that are making rapid strides towards initial builds and testing of novel reactor designs through a combined DOE/NRC licensing approach. As one of just three companies selected for DOME testing of its reactor in the DOE FEED Program back in 2023, Radiant managed to win the #1 testing slot, beating Westinghouse's eVinci for the right to commence testing in 2026, securing what we think could be an early-mover advantage in the race towards full commercial NRC licensing.

This new capital raise, which came together quickly less than a year after the company's Series C, will support the company's DOME testing and scaling of its commercialization efforts, particularly the design and build-out of Radiant's production factory, R-50, being sited in Oak Ridge, Tennessee on an 85-acre parcel of former Manhattan Project land.

Nucleation Capital, whose Fund I is a long-term investor in Radiant, builds boutique portfolios of top ventures innovating within the advanced nuclear and nuclear-adjacent sectors. There is so much demand across every sector for better sources of clean, reliable energy, we believe that there is a huge opportunity for those ventures like Radiant delivering reliable clean power systems that meet the energy needs in specific niches like data centers, remote villages, industrial centers, universities, hospital campuses, marine transport fleets, forward military bases, vehicle charging stations, large towns and urban district heating systems.

Fund I is designed primarily to provide curated and affordablce access for accredited and other high networth investors. Nucleation's Fund II is designed to provide institutional LPs with boutique access to these rarified clean energy sectors, though skewed slightly later stage.

Nucleation's Fund I operates on a quarterly subscription model and accepts new investors (as limited partners or "LPs") on a rolling basis. Investors select the level and term that works for them—from as low as $10,000 to as high as $1 milion per year—and fund on a quarterly basis to receive a pro rata allocation in each of the investments Nucleation makes each quarter. Learn more about participation in Nucleation's Fund I here.

Published by Ian Brusewitz in Advanced Nuclear, Department of Energy, Electrification, Energy transition, Fission, Future of Energy, Investor activity, NEWS, Nuclear competitiveness, Nuclear financing, Portfolio Venture, Private companies, Pro-nuclear campaign, US competitiveness, US technological leadership

September 18, 2025

Radiant signs first Western HALEU Enrichment Deal with U.K.-based Urenco ()

Radiant signed the first binding HALEU enrichment contract by a U.S. reactor developer with European firm Urenco, supporting its Kaleidos microreactor and diversifying fuel supply.

Published by Nucleation Capital in Advanced Nuclear, Advanced Nuclear Customers, Energy transition, Future of Energy, International Collaboration, NEWS, Nuclear R&D, Private companies, Transatlantic News, US competitiveness, US technological leadership

July 21, 2025

Radiant’s Microreactor Hits the Headlines ()

Radiant, a Nucleation portfolio company, was spotlighted in the LA Times for its progress in developing portable, helium-cooled nuclear...

Published by Nuclea_Admin in Advanced Nuclear, Carbon emissions, Climate Costs, Electrification, Energy transition, Fail-safe fuels, National Defense, NEWS, Nuclear innovation, Nuclear R&D, Nucleation communications, Portfolio Venture, Private companies, Solving climate, US competitiveness, Venture capital support for nuclear

March 1, 2022

Rita Baranwal

Dr. Rita Baranwal is the Chief Nuclear Officer at Radiant, a Nucleation portfolio company that pioneers the world’s first mass-produced portable nuclear microreactor. She brings decades of leadership in nuclear innovation, policy, and engineering.

Dr. Rita Baranwal was nominated by the President to serve as the Assistant Secretary for the Office of Nuclear Energy (ONE) and was confirmed by the U.S. Senate on June 20, 2019 (by a vote of 86 to 5), becoming the first woman to ever lead the Office of Nuclear Energy.

In that role, Dr. Baranwal directed programs to promote research and development (R&D) on existing and advanced nuclear technologies that sustain the existing U.S. fleet of nuclear reactors, enable the deployment of advanced nuclear energy systems, support nuclear technology for space and defense applications, and enhance the U.S.A.'s global commercial nuclear energy competitiveness. She also:

Launched innovative programs to demonstrate advanced nuclear reactor designs, launched a new U.S. reactor innovation center, and a unique private-public partnership to develop new U.S. nuclear testing capabilities
Collaborated with U.S. intergovernmental agencies (e.g. Departments of State, Commerce, and Treasury, National Security Council, Office of Science & Technology Policy, Nuclear Regulatory Commission, Development Finance Corporation) to globally deploy new U.S. civil nuclear technology.
Implemented civil nuclear agreements with two countries; initiated civil nuclear agreement discussions with eleven countries.
Partnered with NASA on nuclear technology and expertise for space exploration. Contributed to the National Strategy for Space Nuclear Power and Propulsion, Executive Order on Reactors for Space Exploration, and DOE’s Space Strategy.
Managed Congressionally-enacted budget of $1.5B (FY20).
Served as the Equity in Energy Champion for DOE’s Office of Economic Impact and Diversity.

Following her service as the #1 at ONE, Dr. Baranwal served as the VP of Nuclear and Chief Nuclear Officer for the Electric Power Research Institute (EPRI) for over a year. As of 2022, Dr. Baranwal has returned to Westinghouse as the Chief Technology Officer.

Prior to her appointment to the ONE, Dr. Baranwal served as the director for the DOE's Gateway for Accelerated Innovation in Nuclear (GAIN) since 2016, an initiative hosted at Idaho National Laboratory. GAIN is the way the U.S. Government connects industry with national laboratories to help commercialize nuclear technologies. Under her leadership, GAIN positively impacted 112 projects and companies.

Before that, Dr. Baranwal worked for Westinghouse in the nuclear fuel division, leading a number of research and development programs. She started her career at Bettis Atomic Power Laboratory helping to develop advanced nuclear fuel materials for US naval reactors.

Dr. Baranwal has a bachelor’s degree from Massachusetts Institute of Technology in materials science and engineering and a master’s degree and Ph.D. in the same discipline from the University of Michigan.

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Sources:

LinkedIn: Dr. Rita Baranwal
NayaFace: Rita Baranwal sworn in as 1st woman US Assistant Secretary for Nuclear Energy at DOE, July 25, 2019.

Published by editor in Brilliant thinkers, History-making, Nuclear R&D, Venture capital support for nuclear, Women in Nuclear, WOMEN IN NUCLEAR GRID

December 30, 2021

Radiant Nuclear

Radiant Nuclear – An El Segundo, California-based developer of Kaleidos, a mobile high-temperature gas nuclear microreactor that replaces diesel generators.

Published by Nuclea_Admin in PORTFOLIO