SSN (hull classification symbol)

An SSN is a nuclear-powered general-purpose attack submarine – SSN is the US Navy hull classification symbol for such vessels. SS means "Submarine, General" according to the NATO Standard Ship Designator System with SSN referring to a "Submarine Attack Nuclear" vessel. The "SS" designator is consistent with other examples of STANAG 1166 using double letter referring to a type of vessel – for example, "BB" designates a Battleships, "DD" is a Destroyer, "CC" a Cruiser, "FF" a Frigate, and so on.

History

The first nuclear-powered attack submarine was the US Navy's, operational from 1954. This was followed by the four submarines of the entering service in 1957.
The Royal Navy's first nuclear fleet submarine was which by using an American reactor entered service in 1963. The first all-British nuclear submarines were the two s.
The SS designation has sometimes been incorrectly quoted as being an abbreviation of 'Ship Submersible' but this is not correct – even the Royal Navy have made this mistake in the past on the some of their historical websites.
The USN submarine fleet has been all-nuclear powered for over three decades. The last Barbel-class diesel-electric attack submarine,, was decommissioned in 1990. The bulk of the USN's SSN fleet has been the Los Angeles-class attack submarine. Designed during the Cold War the Los Angeles-class boats raison d'etre was to protect USN carrier battle groups and to hunt Soviet Navy SSBNs before they could launch a first strike against the United States.
The first ever major combat action involving an SSN was during the 1982 Falklands War. An Argentinian cruiser, was sunk by torpedoes fired by the Royal Navy fleet submarine. After that incident, the Argentinian Navy was effectively confined to port.
Since the end of the Cold War, SSNs have evolved into multi-mission submarines. Their roles include submarine-launched cruise missile platforms, intelligence gathering platforms, insertion and exfiltration of special forces teams in addition to traditional hunter-killer SSN roles.
The advantages of an SSN over a conventionally powered SSK are much longer endurance, and higher speed. Unlike most SSKs, SSNs do not have to surface periodically for air, which would compromise their stealth. Some of the newest conventional submarines approach these advantages: Stirling engine powered vessels can cruise underwater for up to two weeks and, like diesel/electric vessels, are significantly quieter than nuclear submarines, since they do not need to run the powerful pumps associated with the cooling circuits of pressurized water reactors.
The main disadvantages of an SSN are the technological challenges and expenses of building and maintaining a nuclear power plant. Nuclear submarines can have political downsides, as some countries refuse to accept nuclear-powered vessels as a matter of policy. Furthermore, decommissioned nuclear submarines require costly dismantling and long term storage of the radioactive waste.
The following navies currently operate SSNs: