Valar Atomics, a three-year-old microreactor startup based in Torrance, California, has closed a $1 billion Series B round led by Sequoia Capital as investors pile into advanced nuclear bets tied to a regulatory overhaul under the Trump administration.
The financing is earmarked to accelerate commercialization of Valar’s Ward 250, a five-megawatt microreactor that uses helium rather than water for cooling. The design has not yet been approved by the U.S. Nuclear Regulatory Commission; the company says the new capital will allow it to move from demonstrations to mass production of integrated reactor systems.
Founder and CEO Isaiah Taylor framed the round as a shift in strategy: Valar intends to scale from proving operability to producing fleets of reactors. The company is pursuing a vertically integrated, hardware-first model that extends from deployment and operations to fuel fabrication.
Valar has drawn attention well beyond the usual startup circles. The young company and its founder previously faced skepticism inside the nuclear industry after bold social-media claims and a legal fight with the NRC, but Taylor’s high-profile outreach also helped cultivate strong ties with Republican officials. That proximity to the Trump administration has translated into federal support: the Department of Energy selected Valar for two pilot programs—one aimed at helping next-generation reactors reach first criticality and another focused on advanced nuclear fuel supply chains. Valar also became the first venture-backed firm to achieve fission with an experimental core at Los Alamos National Laboratory.
In a widely publicized test, the company loaded components for the Ward 250 onto a C-17 Globemaster III at March Air Reserve Base and flew them to Hill Air Force Base in Utah, demonstrating that a microreactor can be transported entirely by air. In June, its prototype Ward 250 reached criticality as part of the DOE pilot program.
Valar’s plan to produce its own fuel compounds the challenge. The company intends to use TRISO fuel, a complex particle fuel form that offers safety advantages but is difficult to manufacture at scale; only a handful of domestic suppliers are currently working to expand TRISO production.
The technology itself has a mixed track record. High-temperature gas-cooled reactors (HTGRs) were operated in the U.S. decades ago—the Fort St. Vrain plant in Colorado ran into maintenance and reliability problems and closed after about ten years—but the design has been used experimentally in a few places worldwide. China has been the most active developer recently: it began commercial electricity sales from a 150-megawatt helium-cooled reactor in late 2023 and has continued to accelerate construction and industrial cooperation on larger units.
That international activity, and recent strains on water-cooled plants during heat waves in Europe, have helped rekindle interest in helium-cooled HTGRs. Still, microreactors and small modular reactors must prove they can be economically viable: the nuclear industry historically benefits from scale, not from selling many small units.
Valar will also face competition from better-funded rivals. Kairos Power, backed in part by Google, recently broke ground on a commercial plant in Tennessee. X-energy, in which Amazon has invested, won a key federal approval for its first project earlier this year. Both firms are pursuing different advanced reactor approaches and lack overt partisan ties.
Valar’s political connections cut both ways. The company’s alignment with the Trump administration has helped secure resources and publicity, but those same ties could become liabilities if political winds shift. The Sequoia partner who led the Series B, Shaun Maguire, will join Valar’s board; Maguire is a vocal Trump supporter whose past remarks were widely condemned as bigoted against Muslims, a controversy that may attract further scrutiny as the startup grows.
Even with deep pockets, Valar faces technical, supply-chain, regulatory and market hurdles before its Ward 250 becomes a commercial product. The $1 billion infusion gives the company room to pursue its vertically integrated vision—manufacturing reactors, developing fuel supply, and scaling deployments—but success is far from assured.
This article is adapted from reporting by Alexander C. Kaufman for Canary Media and is republished under a Creative Commons license.
