The US Navy has had X nuclear power incidents and accidents in the past 60 years.
Only one I can think of was the USS Thresher in the Atlantic.
Only two that I can think of, both primary coolant leaks, one in a submarine near Puget Sound in the 70s, and another on the carrier Nimitz. There are also at least two submarines at the bottom of the Atlantic, lost in the 60s to "unknown” causes.
The US Navy. Zero that I know of.
The Soviets/Russians, a few. At least 2 that I know of.