Kairos Power has tapped engineering firm Samsung C&T to help build its 50-megawatt demonstration reactor for Google, a project the nuclear startup aims to wrap up by 2030 - because nothing says "move fast and break things" like a timeline measured in geological epochs.

As part of the deal, Samsung C&T will make an equity investment in Kairos and provide "in-kind" engineering services, a combination worth up to $100 million, Kairos Power announced Monday. The equity investment accounts for $70 million of that total, a Kairos spokesperson told TechCrunch. For those keeping score at home: that's $70 million in actual money and $30 million in the corporate equivalent of "we'll owe you one."

Samsung C&T has built or helped build roughly a dozen nuclear reactors around the globe, which is the kind of résumé line that makes you either very reassured or very nervous, depending on how you feel about the phrase "helped build."

Kairos is part of a wave of nuclear startups that have benefited from the surge in power demand from AI data centers - the same data centers that are currently generating more heat than the reactors meant to power them. 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. That's enough to power a small city, or one particularly ambitious chatbot.

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 - a rare instance of a tech timeline actually being met, assuming it happens.

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 - a feature that is generally considered desirable in a nuclear reactor.

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, which is the nuclear equivalent of wrapping your valuables in bubble wrap and hoping for the best.

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 - an industry where "manageable" often means "we'll see." 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, assuming the laws of physics and corporate bureaucracy remain equally flexible.