Kairos Power selects Samsung C&T to build 50 MW demonstration reactor for Google

Kairos Power has picked engineering firm Samsung C&T to help build its 50 megawatt demonstration reactor for Google, which the nuclear startup is aiming to have completed by 2030.

As part of the deal, Samsung C&T will make an equity investment in Kairos and provide “in-kind” engineering services, the combination of which is worth up to $100 million, Kairos Power said Monday. The equity investment will make up $70 million of the total, a Kairos spokesperson told TechCrunch.

Samsung C&T has built or helped build about a dozen nuclear reactors around the globe.

Kairos is part of a wave of nuclear startups that have benefited from the surge in power demand from AI data centers. Google first signed a deal with the company in fall 2024, calling on Kairos to build nuclear reactors capable of generating about half a gigawatt of electricity by 2035.

Currently, Kairos is building two reactors in Oak Ridge, Tennessee. The first, Hermes 1, is a low-power demonstrator that will help the company refine its commercial design. The second, Hermes 2, is Kairos’s first commercial-scale reactor. Output from Hermes will count as the first 50 megawatts of its deal with Google.

The startup received approval from the Nuclear Regulatory Commission to build the reactors in November 2024. It expects Hermes 2 to begin operating in 2030, in line with its original agreement with Google.

Hermes 2 will be a fluoride salt-cooled high-temperature reactor, a design that has been floated for years but never built at commercial scale. Fluoride salts have high boiling points, which will help keep pressure levels low. That, in turn, will limit the risk of high-pressure blowouts in case of any parts failures.

Kairos is also using a relatively new form of nuclear fuel known as TRISO, which encapsulates tiny seeds of uranium fuel in layers of ceramic and carbon, which are then loaded into billiard ball-sized spheres. The arrangement is intended to prevent meltdowns.

The startup has about five years to get its first power plant up and running, which is an accelerated but manageable timeline in the nuclear industry. To fulfill the terms of its deal with Google, Kairos will need to move even faster on subsequent reactors, something Samsung C&T might be able to help with.