The first commercial contract for power from an advanced Gen IV reactor in the United States is small in megawatts and large in precedent. On August 18 Google, Kairos Power and the Tennessee Valley Authority announced a power purchase agreement under which TVA will buy up to 50 MW from Kairos's Hermes 2 plant in Oak Ridge, Tennessee. The plant is scheduled to begin operations in 2030. Google will receive the clean energy attributes through TVA's system to serve its data centers in Montgomery County, Tennessee, and Jackson County, Alabama.
The structure is the news as much as the reactor. Rather than signing directly with a developer and arranging delivery around a utility, Google has put the utility in the middle, as the buyer of the power and the operator of the grid that carries it.
How the deal works
Google described the arrangement as a three-party solution. TVA buys the electricity from Kairos. Google buys the clean energy attributes from TVA, matched to its regional data center load, which it says will help it power those sites with locally sourced clean energy every hour of the day. TVA says it is the first U.S. utility to sign a PPA for electricity from an advanced Gen IV reactor.
Hermes 2 is the first deployment under the master agreement Google and Kairos signed in October 2024, which aims to bring up to 500 MW of advanced nuclear capacity online by 2035 to support Google's load growth. To speed delivery, Kairos said it will increase Hermes 2's output from 28 MW to 50 MW, generated by a single reactor rather than the earlier two-reactor configuration. CNBC put the output at the equivalent of about 36,000 homes.
The reactor
Kairos is developing a fluoride salt-cooled, high-temperature reactor. According to POWER magazine, Hermes 2 will use a molten fluoride salt known as Flibe as coolant and TRISO fuel in pebble form, allowing high-temperature, low-pressure operation, with a Rankine steam cycle to convert heat into electricity. The NRC issued construction permits for the 70 MW thermal Hermes 2 facility in November 2024 at the East Tennessee Technology Park in Oak Ridge. Kairos told POWER it had reviewed the design changes and concluded that the conditions of the construction permit were not substantively affected, so an amendment was not required; it will include the design details in a future operating license application.
Hermes 2 will share a site with Hermes 1, a 35 MW thermal non-power demonstration reactor. Kairos broke ground on Hermes 1 in July 2024, and safety-related nuclear construction began in May 2025 with the first pour of safety-related concrete, according to POWER. Hermes 1 is expected online in 2027. CNBC notes that Kairos still needs an NRC operating license before Hermes 2 can run.
Why TVA
TVA is a natural first buyer. The federal power corporation already runs seven reactors at three sites, which POWER says supply roughly 40% of its generation, one of the largest nuclear shares of any U.S. system. It is also pursuing its own small modular reactor. In May 2025 TVA became the first U.S. utility to submit a construction permit application to the NRC for the BWRX-300 design from GE Vernova Hitachi Nuclear Energy, at its Clinch River site, which holds an early site permit issued in 2019. That project could deliver up to 300 MW gross.
Demand is the driver. On TVA's July earnings call, chief executive Don Moul said that with the same 96 degree temperature as the previous June, TVA saw demand roughly 500 MW higher this year, which he attributed to population growth, economic expansion and new electricity-dependent technologies. TVA's planning assumption includes more than 6,200 MW of new firm, dispatchable generation pending approvals, POWER reported. Earlier in July, TVA signed commercial contracts with Type One Energy for a planned 350 MW fusion plant by the mid-2030s.
What 50 MW means
Fifty megawatts will not change the arithmetic of Google's electricity use. A single large AI campus can draw many times that. What it changes is the risk profile of the first commercial unit. A developer with a first-of-a-kind reactor needs a credible offtaker before it can finance construction; a utility with a statutory obligation to serve needs confidence that any new technology it buys will not burden other customers if it runs late or over budget. Placing a hyperscaler behind the utility contract offers both.
For Google, the payoff is hourly matching. The company has pursued a goal of running on carbon-free energy every hour of every day. Solar and wind can cover large shares of that goal in some hours but not in others. A reactor running steadily on TVA's grid provides output in the hours that variable resources miss, and the attributes stay tied to the region where Google's data centers sit.
The model is also replicable. If Hermes 2 runs as planned, the remaining 450 MW under the Google agreement could follow the same route, with utilities buying the power and Google buying the attributes. Kairos would then be selling reactors into regulated utility planning processes rather than one corporate contract at a time.
The risks
Every element of the timeline has to hold. Hermes 1 must come online and operate as planned. The redesign of Hermes 2 must survive the operating license review. The supply chain for TRISO fuel and high-purity fluoride salt must scale. None of those is guaranteed, and first-of-a-kind nuclear projects in the United States have a long record of delays.
The contract also leaves TVA's broader problem unsolved. Its planning assumption calls for thousands of megawatts of firm capacity, and Hermes 2 supplies 50. Most of the gap will be filled by gas, existing nuclear and other resources over the next decade. The value of the Kairos deal lies in what comes after 2030, if the technology proves itself.
That is why the agreement matters beyond its size. It shows a way for data center demand to pull new reactor designs into the utility system: through a regulated buyer, with the technology company paying for the clean attributes and the utility keeping control of the grid.