Advanced Reactors

Prime Minister Narendra Modi proclaimed it “a proud moment for India” when on April 6 the 500-MWe, sodium-cooled Prototype Fast Breeder Reactor (PFBR) achieved initial criticality. This milestone, which comes some 22 years after the continually delayed PFBR project began, marks India’s entrance into the second stage of its three-stage nuclear program, which has the ultimate goal of supporting the country’s nuclear power program with its significant thorium reserves.

On Wednesday, Idaho National Laboratory announced that the National Reactor Innovation Center’s Demonstration of Microreactor Experiments (DOME) test bed is now “open for business.”

With DOME’s opening, microreactor developers will soon be able to test, demonstrate, and validate their reactor designs. Rian Bahran, the Department of Energy’s deputy assistant secretary for nuclear reactors, called this “essential infrastructure” a “testament to our commitment to a robust nuclear future” and a key tool for “accelerating the development and deployment” of new energy technologies.

Valar's Ward250 microreactor being loaded, without fuel, onto a C-17 aircraft. (Photo: Valar Atomics)

A public-private partnership between the Departments of Defense and Energy and Valar Atomics marked a milestone over the weekend when Valar’s Ward250 microreactor was transported (without fuel) from California to Utah using three C-17 aircraft. The reactor will now trek from Hill Air Force Base to the Utah San Rafael Energy Lab (URSEL) for testing and evaluation.

A formal press conference at Hill Air Force Base included Energy Secretary Chris Wright, Undersecretary of Defense Michael Duffey, Utah Gov. Spencer Cox, and Valar Atomics CEO Isaiah Taylor.

During his remarks, Wright discussed the significance of the day, and said “a 5‑megawatt Valar Atomics nuclear reactor was just flown from L.A. to this air force base here in Utah—an incredible 5‑megawatt reactor that powers 5,000 homes, flown in the back of a plane.” The ability to transport microreactors like the Ward250 bolsters claims that the technology could be deployed to remote locations, military installations, or to support natural disaster relief missions.

An opportunity to request an adjudicatory hearing for Duke Energy Carolinas’ early site permit (ESP) application for the Belews Creek site in Stokes County, N.C., has been announced by the Nuclear Regulatory Commission. The notice of the opportunity was published February 9 in the Federal Register. The deadline to file a request for a hearing or petition for leave to intervene is April 10, 2026.

French advanced reactor developer Stellaria has formally submitted an application with the French government for authorization to build a prototype of its fast breeder molten salt reactor concept, known as Stellarium.

The company, which spun out of the country’s Alternative Energies and Atomic Energy Commission (CEA) and Schneider Electric, filed an application for authorization to create (DAC) for the reactor with the government minister in charge of nuclear safety, making it the first French start-up to submit an application with the authorities for a fast-neutron reactor.

Two participants in the Department of Energy’s Reactor Pilot Program have recently announced significant milestones on their associated reactor projects. Aalo Atomics successfully completed its final design review (FDR), and Antares Nuclear has received DOE approval of its preliminary documented safety analysis (PDSA).

Nuclear power in space is back in the news for the second time this week as microreactor start-up Nano Nuclear has released a request for information to identify organizations that may support the company in the development of its Loki micro modular reactor. The company’s goal is eventual deployment of Loki on the lunar surface.

Tech giant Meta is making big bets on TerraPower and Oklo. With the former, the hyperscaler could support the deployment of up to eight new reactors. With the latter, it could be as many as sixteen.

For both start-ups, Meta hopes its demand bolsters supply chains, the workforce, and the nuclear industry generally. For itself, the company is aiming to secure more generation to cleanly power its AI ambitions.

This week, the Department of Energy has finalized two new other transaction agreements (OTAs) with participating companies in its Reactor Pilot Program, which aims to get one or two fast-tracked reactors on line by July 4 of this year. Those companies are Terrestrial Energy and Oklo.

New York City–based Nano Nuclear Energy has signed a memorandum of understanding with the University of Illinois Board of Trustees, on behalf of the University of Illinois–Urbana-Champaign, to collaborate on the development, construction, and operation of the company’s Kronos MMR (micro modular reactor) as an on-campus research reactor. The new MOU represents the latest aspect of Nano Nuclear’s partnership on the Kronos MMR project with the university, which includes state funding for a manufacturing and research center, to be located in the Chicago suburb of Oak Brook.

Following up on an October announcement on plans to invest more heavily in nuclear power, Duke Energy closed out 2025 by submitting an early site permit application to the Nuclear Regulatory Commission. This ESP application is for a site near the Belews Creek Steam Station, a coal and natural gas plant in Stokes County, N.C., where Duke has been pursuing a new nuclear project for two years.

Progress in the Department of Energy’s Reactor Pilot Program continues as Natura Resources has executed an Other Transaction Agreement (OTA) with the DOE for the company’s Molten Salt Research Reactor being pursued in close collaboration with Abilene Christian University (ACU) in Texas. Reactor projects participating in the program would progress through DOE authorization and oversight rather than Nuclear Regulatory Commission licensing.

GE Vernova Hitachi Nuclear Energy’s BWRX-300 small modular reactor has completed the second step of the generic design assessment (GDA) process in the United Kingdom. In this step, the U.K. Office for Nuclear Regulation, the Environment Agency, and Natural Resources Wales did not identify “any fundamental safety, security safeguard or environmental protection shortfalls with the design of the BWRX-300.” Step 1 was completed in December 2024.

With about seven months left in the race to bring DOE-authorized test reactors on line by July 4, 2026, via the Reactor Pilot Program, Deep Fission has announced that it will break ground on its associated project on December 9 in Parsons, Kansas. It’s one of many companies in the program that has made significant headway in recent months.

Idaho National Laboratory has selected five teams for its Microreactor Application Research Validation and Evaluation (MARVEL) Project to develop a sodium-potassium–cooled microreactor designed to test microreactor applications, create regulatory processes, and explore electrical and nonelectrical uses.

Advanced nuclear energy start-up Antares has announced the close of a $96 million Series B funding round, led by Shine Capital with participation from Alt Capital, Caffeinated, FiftyThree Stations, Industrious, and other investors. The round raised $71 million in new equity capital and $25 million in debt for equipment, factory build-out, and uranium procurement.

The Department of Energy has selected the Tennessee Valley Authority and Holtec Government Services to support the early deployments of light water small modular reactors in the United States. The companies will each receive as much as $400 million in federal cost-shared funding to advance their initial SMR projects in Tennessee and Michigan, respectively, including follow-on projects and associated supply chains.

The Nuclear Regulatory Commission recently announced that it has completed its final safety evaluation (SE) for the construction permit application for Kemmerer Power Station Unit 1 in Kemmerer, Wyo. The application was submitted by TerraPower on behalf of its wholly owned subsidiary, US SFR Owner (USO).

The Department of Energy recently announced that General Atomics has successfully completed the conceptual design of its new helium gas–cooled fast modular reactor (FMR). This milestone moves the company one step closer to a target demonstration in the 2030s.

Advanced reactor developer X-energy has announced that it has closed an oversubscribed Series D financing round of approximately $700 million. The funding proceeds are expected to be used to help continue the expansion of its supply chain and the commercial pipeline for its Xe-100 advanced small modular reactor and TRISO-X fuel, according the company.