Molten salt nuclear reactors slated to power Google datacenters in 2030

More than 60 years after first demos of this tech, Kairos will bring it back to Oak Ridge

Oak Ridge, Tennessee, could be home to a molten salt reactor once again if Google-backed Kairos Power has its way.

The small modular reactor startup, along with the Tennessee Valley Authority (TVA), one of the largest utilities in the country, aim to bring 50 megawatts of nuclear power to Tennessee.

The Chocolate Factory, which tapped the start-up last northern Autumn to provide up to 500 megawatts of carbon-free atomic power, said on Monday it would be among the first to benefit from Kairos' Hermes 2 demonstration plant when it comes online in 2030. The twin reactor facility is set to supply power to Google's datacenters in Tennessee and Alabama.

Kairos is also setting up a simulator at the University of Tennessee to train technicians to operate the facility.

The city of just over 34,000 is a fitting location for the plant, as Kairos' reactor tech can trace its roots back to the Department of Energy's (DoE) Oak Ridge National Laboratory's (ORNL) molten salt reactor experiments of the 1950s and '60s.

Built in 1954, ORNL's Aircraft Reactor Experiment was first to demonstrate the viability of a molten salt reactor. While the design proved too heavy – and presumably too dangerous – for flight, just over ten years later a scaled-up version of the reactor went critical, operating for four years until 1969.

Kairos' reactor designs are based on a similar concept, and will use Tri-structural ISOtropic (TRISO) fuel pellets, which are essentially a tiny grain of uranium encased in carbon and ceramic. Fuel-makers press the pellets into billiard ball-sized pebbles which are cooled by molten fluoride salts, just like ORNL's earlier reactor experiments.

Power is generated indirectly by pulling heat from the salts to power a steam generator and turbine.

Google isn't the only hyperscaler to embrace small modular reactors (SMRs). Oracle plans to deploy at least three SMRs to power a gigawatt-scale datacenter, and Amazon has tapped X-Energy SMR tech to offset its growing datacenter footprint.

However, Google's choice of SMR startups could give it a leg up as Kairos is one of the few SMR startups to get Nuclear Regulatory Commission (NRC) approval to construct a pair of 35 megawatt test reactors. However the NRC will still have to sign off on the facility before the plant can start generating power.

Just because the NRC has signed off on the project doesn't mean Kairos will build it. As you may recall, back in 2023 the NRC signed off on NuScale's reactor, clearing the way for a six-reactor 462-megawatt power plant in Utah. Unfortunately the project was later abandoned after several municipalities pulled out of the deal, citing rising costs.

And according to researchers at Institute for Energy Economics and Financial Analysis, SMRs may never be cost effective. In a report published last year, they argued that the tech was "still too expensive, too slow to build, and too risky to play a significant role in transitioning away from fossil fuels."

But with energy availability a major reason for slow cloud and hyperscale datacenter expansions, the economics could be changing. Over the past year, we've seen major cloud providers invest heavily in nuclear. Microsoft even went so far as to finance the re-ignition of the shuttered Three Mile Island Unit 1 reactor while Amazon is currently building out a datacenter campus alongside the Susquehanna nuclear plant. ®