Google, Kairos and TVA Write the First Utility Contract for Gen IV Nuclear

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.

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. 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.

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. 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.

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. The company has pursued a goal of running on carbon-free energy every hour of every day.