The American nuclear reactor firm Kairos Power and South Korea's Samsung C&T have signed a deal worth up to 100 million dollars (around 92 million euros) to build a 50-megawatt demonstration reactor. Of that money, 70 million is an equity investment and the rest is engineering work instead of cash. The buyer of the electricity is known in advance: Google.

The deadline is 2030, and the ambition is larger - around 500 megawatts of nuclear capacity for Google by 2035, under a partnership agreed back in the autumn of 2024. Kairos is already building two reactors in Oak Ridge, Tennessee: Hermes 1 as a low-power demonstration and Hermes 2 as the commercial version. The US Nuclear Regulatory Commission approved both in late 2024.

The technology is not conventional. Hermes 2 uses a high-temperature fluoride-salt-cooled reactor and TRISO fuel - uranium sealed in ceramic and carbon layers inside pebbles the size of a billiard ball. The aim of that design is to make a core meltdown physically harder and to reduce the risk of a pressure-related accident. Samsung C&T, for its part, brings experience from around twelve reactors built or supported worldwide.

It is worth pausing on the order of events here. This is not a state building a nuclear plant and then selling the electricity on a market. This is one company that bought the entire output in advance - before it is built, before it is switched on. When data centres started eating more power than the grids can supply, the biggest players did not reach for savings. They reached for their own power stations.

Whether that is good or bad depends on where you stand. In engineering terms, private money financing a new generation of reactors is exactly what the nuclear industry has been waiting decades for. But politically, something is being born here that regulators still have no words for: infrastructure of national significance, built, paid for and reserved in advance by a single corporate buyer. Who decides what happens to those megawatts if the grid needs them tomorrow?