Commits to molten salt small modular reactors it thinks can come online in 2035

Google has become the latest tech giant to seek nuclear power as a source for its datacenters and other operations.

The ads and search giant on Monday announced it had purchased nuclear energy from multiple small modular reactors (SMRs) to be developed by an outfit called Kairos Power.

Kairos describes its tech as "a novel advanced reactor technology that leverages TRISO fuel in pebble form combined with a low-pressure fluoride salt coolant. The technology uses an efficient and flexible steam cycle to convert heat from fission into electricity and to complement renewable energy sources."

TRISO is an abbreviation for "TRi-structural ISOtropic particle fuel" and according to the US Department of Energy is "the most robust nuclear fuel on Earth."

The Department explains that the fuel is formed into pellets about the size of a poppy seed that has three outer layers of carbon and ceramic-based materials that shield an inner kernel of uranium, carbon and oxygen. A Kairos video mentions fuel pellets the size of a table tennis ball.

Whatever size balls TRISO is used to make, each contains uranium, carbon and oxygen. The idea is that the pellets are always so small that if one ruptures, it would not produce enough energy to trouble the shielding of other pellets and cause a reactor accident.

The fuel is floated in a tank full of molten salt that absorbs the heat the fuel produces. As the Kairos diagram below shows, the resulting hot molten salt is pumped into heat exchangers and the heat used to make steam that's fed into a turbine.

If things go wrong, the molten salt provides passive cooling.

Kairos is yet to deliver a working reactor, but broke ground on a test facility this year and hopes to deliver a working facility in 2030, then deploy more from 2035. Its designs are scoped to produce 150 MWE - 150 million watts of energy.

Google's senior director of energy and climate, Michael Terrell, wrote that the Chocolate Factory hopes backing Kairos sparks a chain reaction.

"By procuring electricity from multiple reactors - what experts call an 'orderbook' of reactors - we will help accelerate the repeated reactor deployments that are needed to lower costs and bring Kairos Power's technology to market more quickly," he wrote.

Terrell wrote that Google's deal with Kairos "will enable up to 500MW of new 24/7 carbon-free power to US electricity grids."

Which will be lovely if it happens.

But SMRs are not a proven technology. The Nuclear Energy Agency's Small Modular Reactor Dashboard: Second Edition lists three working reactors - one each in China and Russia, plus a test reactor in Japan - and over 50 groups working on designs.

Many of those designs await approval. Kairos, however, is one of three companies whose designs are approved by US authorities, and the Agency rates its financing and engagement with communities and elected representatives as strong. Maybe Google has picked a good partner as it joins the likes of Oracle, Microsoft, and Amazon by investing in nuclear energy. ®