Samsung C&T to Put Up to $100 Million Into Kairos Power's Google-Backed Nuclear Reactor

Kairos Power announced Monday that it has picked Samsung C&T Engineering & Construction Group to help finish building its Hermes 2 demonstration reactor in Oak Ridge, Tennessee. Samsung C&T will put up to $100 million into the project through a mix of direct equity investment and in-kind engineering services.

A Kairos Power spokesperson told TechCrunch that $70 million of that figure is an equity investment, with the remainder covering engineering work. The investment firm Whales Book reported the same split: $70 million in equity, $30 million in services.

Dealroom, however, described the arrangement differently, reporting that Kairos "signed a binding term sheet for US$64.7M late-stage investment led by Samsung C&T" separate from the in-kind engineering commitment. The exact breakdown of cash versus services has not been reconciled across these accounts, and neither Kairos nor Samsung C&T has issued a public itemization beyond the "up to $100 million" topline figure.

What isn't in dispute: this is the first major financial commitment behind Hermes 2, the reactor Kairos needs operating by 2030 to start delivering power under its 2024 agreement with Google. That deal calls for Kairos to build reactors capable of generating roughly half a gigawatt for Google by 2035, with Hermes 2's output counting as the first 50 megawatts.

A Company That's Actually Built Reactors

Samsung C&T isn't a Silicon Valley financier dabbling in nuclear. The firm has built or helped build about a dozen reactors worldwide. Under the new arrangement, Samsung C&T joins Kairos's integrated engineering, procurement and construction team, focusing first on power-generation systems and what the industry calls balance-of-plant work.

Kairos CEO Mike Laufer framed the deal as a bet on execution rather than design. "Samsung C&T's investment and partnership reinforce the disciplined delivery model at the core of our commercialization strategy," Laufer said. Chief Technology Officer Ed Blandford put it more bluntly: "Deploying advanced nuclear energy at commercial scale requires strong, capable partners across the full project lifecycle."

The investment builds on a memorandum of understanding signed August 18, 2026, when Kairos, Samsung C&T and Cambridge Vacuum Engineering agreed to a 12-month exploration phase on a workforce and manufacturing initiative called NuCAMP, alongside Oak Ridge National Laboratory, the University of Tennessee-Knoxville, Barnard Construction and two Tennessee community colleges. That earlier deal was advisory in nature. Monday's announcement puts actual money behind it.

The Technology and the Catch

Hermes 2 is a fluoride salt-cooled, high-temperature reactor, a design that has been discussed in nuclear engineering circles for decades but never built at commercial scale. The fluoride salts have high boiling points, which keeps the system running at low pressure and, in theory, reduces the risk of a high-pressure blowout if components fail.

Kairos also uses TRISO fuel, tiny uranium particles wrapped in ceramic and carbon and packed into billiard-ball-sized spheres, a design intended to make meltdowns effectively impossible even at high temperatures.

The Nuclear Regulatory Commission approved construction of both Hermes 1 and Hermes 2 in late 2024. Hermes 1 is a smaller, low-power unit meant to help Kairos refine its commercial design; Hermes 2 is the company's first reactor built at commercial scale.

That approval doesn't erase the risk. Whales Book, an investor-focused outlet, flagged the obvious concern for anyone watching this space: nuclear construction is capital-intensive, timelines slip, and even NRC-approved projects can run into cost overruns or technical delays before they ever generate a watt. Kairos has roughly five years to get Hermes 2 online, an aggressive but not unprecedented timeline in an industry known for blowing through both. Dealroom separately noted the $100 million round ranks in the top 10% of all-time late-stage venture deals in U.S. energy, evidence of how much private capital is now chasing advanced nuclear as AI data centers strain the grid.

A signed MOU and a term sheet are not a running reactor. Kairos still has to move from paper commitments to poured concrete, and it has to do it faster on every subsequent reactor if it wants to hit Google's 500-megawatt target by 2035. Whether Samsung C&T's construction experience actually compresses that timeline, or just adds another layer of coordination to an already complex build, is something only the next few years of pours, inspections and NRC sign-offs will answer.