Google commits to buying power generated by nuclear-energy startup Kairos Power

Small nuclear plants have been tried and failed multiple times.

Elaborate.

China and Russia use them quite effectively.

You dock them right on the shore and it powers an entire remote village / small city.

As another user pointed out, they've also been used by the US military for many decades to power carriers and subs without incident.

The US and Russian navies use them very effectively

Military reactors do not have to be economical in any sense. They are not candidates for civilian power.