Nuclear submarines are powered by a nuclear reactor and they are completely independent of air, so there is no need to surface frequently.
USA has the most nuclear submarines
Argentina had diesel-electric submarines while the British had nuclear-powered submarines.
A number of nuclear submarines sank, and the circumstances vary from accident to accident. Wikipedia has a list, and by going there and entering "List of sunken nuclear submarines" you can review that list.
The US, Russia, Great Britain, France, China and (recently) India have nuclear submarines.
Yes, nuclear submarines generate nuclear power. There is a nuclear reactor on board (hence the tern nuclear submarine) which creates steam to drive the main engines to turn the screw(s).
Nuclear Energy
The PLA navy has more than 225,000 personnel and is thought to have as many as 70 submarines, 10 of them nuclear-powered
No - all submarines, be it nuclear or diesel-electric, use diesel fuel, either for primary engines (DE) or backup generator (nuclear).
Plutonium can be used in nuclear reactors for nuclear propulsion of ships and submarines.
Since its free-fall nuclear weapons arsenal was decomissioned in 1998, the United Kingdom's only means of nuclear weapons delivery is via submarines and SLBMs.
Nuclear energy is used to power most modern submarines
As of October 2023, India has a total of 15 operational nuclear submarines, which include both ballistic missile submarines (SSBNs) and attack submarines (SSNs). The country operates four SSBNs, known as the Arihant-class, and is in the process of expanding its fleet. Additionally, India has several nuclear-powered attack submarines, enhancing its underwater capabilities. The exact number may vary as new submarines are commissioned or undergo maintenance.