What was the name of the first naval nuclear-powered vessel?

The name of the first naval nuclear-powered vessel is indeed USS Nautilus. Launched in 1954, USS Nautilus was a groundbreaking achievement for the United States Navy and the nuclear propulsion program. It was the first submarine to be powered by a nuclear reactor, which allowed it to operate for extended periods without the need to surface for air, revolutionizing submarine capabilities.

USS Nautilus crossed under the North Pole in 1958, demonstrating the operational advantages of nuclear propulsion, such as increased endurance and reduced logistical constraints compared to conventional diesel-electric submarines. This marked the beginning of the era of nuclear-powered vessels in the U.S. Navy and set the stage for future developments in naval technology.

The other vessels listed were significant in their own right but came later or operated with conventional propulsion or different technologies. USS Enterprise was the first nuclear aircraft carrier, USS Long Beach was the first nuclear-powered cruiser, and USS Reagan is a modern aircraft carrier but does not represent the naval nuclear propulsion milestone that USS Nautilus established.