Three-year-old California-based microreactor developer Valar Atomics has closed a landmark $1 billion Series B funding round, backed by growing investor optimism that upcoming reforms to U.S. nuclear regulations will unlock the first large-scale expansion of American nuclear power generation in more than 50 years. Headquartered in Torrance, the startup announced this week that the round was led by top-tier venture capital firm Sequoia, with proceeds earmarked to prepare the 5-megawatt Ward 250 reactor — a helium-cooled design that deviates from traditional water-cooled nuclear technology — for full commercial launch. As of the announcement, the innovative reactor design has not yet received regulatory approval from the U.S. Nuclear Regulatory Commission (NRC).
Valar founder and CEO Isaiah Taylor framed the new capital injection as a critical turning point for the company in a post on the firm’s official website. “This has been Valar’s mission since its inception: to transition from demonstrating the operability of an integrated reactor system to producing fleets of them en masse,” Taylor wrote, noting the funding enables the next critical stage of the company’s development.
Valar’s journey to this $1 billion milestone has been anything but conventional. Once a target of industry derision for bold social media claims made by its 27-year-old founder during a lawsuit against the NRC, the startup’s patriotic framing and high-energy showmanship quickly caught the attention of Republican officials, eventually earning it the label of “the Trump administration’s favorite nuclear startup” from investigative outlet Mother Jones. The startup has leveraged its close ties to the current administration to secure key access to federal programs and national lab resources over the past two years.
The company’s rapid progress unfolded across 2024 and 2025, with a string of industry firsts. In August 2024, the U.S. Department of Energy selected Valar as one of just 10 companies to join a new pilot program designed to support next-generation nuclear startups in completing their first controlled fission reactions. A month later, the agency tapped Valar as one of four participants in a separate initiative to build out new domestic nuclear fuel supply chains. Just two months after that selection, Valar made history as the first venture-backed nuclear startup to complete fission using an experimental core at Los Alamos National Laboratory.
In early 2025, Valar notched another first: the company loaded all components of its Ward 250 prototype onto a C-17 Globemaster III military transport aircraft at California’s March Air Reserve Base and flew the full unit to Utah’s Hill Air Force Base. The airlift, hailed as “groundbreaking” by the Trump administration, served as the first real-world demonstration that a complete microreactor could be transported via air, a key logistical advantage for remote or distributed deployment. By June 2025, Valar had completed fission with its full Ward 250 prototype, becoming the second participant in the DOE’s pilot program to hit that milestone.
In its announcement this week, Valar confirmed the new funding will support a fully vertically integrated, hardware-first operational strategy, covering every stage of the business from reactor deployment and long-term site operations to in-house nuclear fuel production. Despite this rapid progress and investor confidence, the company still faces substantial technical, regulatory, and market hurdles to bring its technology to mass market.
High-temperature gas-cooled reactors, the category Valar’s helium-cooled design falls into, have a checkered history in the U.S. The only U.S. commercial facility of this type, Colorado’s Fort St. Vrain nuclear station, operated from the 1970s before shutting down after a decade of costly maintenance problems and unplanned outages, eventually being replaced by a natural gas power plant. While a small number of similar reactors have been built globally, most have only ever operated as experimental test units.
China has emerged as the global frontrunner in commercializing this technology in recent years, accelerating a global race to deploy helium-cooled reactors that offer a key advantage: they do not require large volumes of water for cooling, eliminating a major vulnerability for water-constrained regions and utilities facing drought-related generation cuts amid climate change. Beijing began construction on its first large-scale high-temperature gas-cooled reactor in 2012, achieved first fission in 2021, and connected the 150-megawatt unit to the national grid to sell commercial power in December 2023. Two years later, China launched a national industrial alliance to speed up development of the technology, and broke ground on a second larger reactor with four times the capacity of the first unit in early 2026.
For the U.S. industry, the benefits of helium-cooled designs have been thrown into sharp relief recently, as record-breaking heat waves across Europe have forced water-cooled inland nuclear plants to reduce output to avoid raising river water temperatures to dangerous levels. Even with this clear strategic advantage, however, developers of small modular reactors (defined as units producing less than 300 megawatts) and microreactors (units under 20 megawatts) still need to prove their business model is economically viable. For decades, nuclear plant operators have generated profits by building large, high-output facilities, not scaling production of large fleets of smaller units.
Valar’s plan to manufacture its own TRISO fuel, a specialized complex fuel form required for its reactor design, adds another layer of challenge. Currently, only a handful of domestic suppliers are working to scale up TRISO production in the U.S., creating potential supply chain bottlenecks for the startup.
Beyond technical and economic hurdles, Valar also faces intense competition from well-funded established players in the advanced nuclear space. Kairos Power, which broke ground on its first commercial plant in Tennessee earlier this year, counts backing from Google’s parent company Alphabet. X-energy, which secured a key NRC approval for its first project in May 2025, counts retail and tech giant Amazon as an equity stakeholder. Unlike Valar, neither competitor is closely aligned with a particular political party, a difference that could have strategic implications.
Valar’s close ties to the Trump administration, which have been a major advantage in securing access and support today, could become a significant liability if Democrats regain the White House and control of Congress in future elections. Already, former President Trump’s close personal ties to the nuclear industry are facing growing scrutiny from watchdogs and lawmakers, and Valar’s latest fundraising round is likely to amplify that attention. The Sequoia partner who led the Series B round, Shaun Maguire, is a prominent public supporter of Trump who became a center of controversy last year over widely condemned bigoted remarks targeting Muslims. As part of the funding deal, Maguire will take a seat on Valar’s board of directors.
This article was originally published by Canary Media under a Creative Commons license, with reporting from award-winning energy and climate journalist Alexander C. Kaufman.