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; the SS denotes a submarine and the N denotes nuclear power.

History
The first nuclear-powered attack submarine was the US Navy's USS Nautilus operational from 1954. This was followed by the four submarines of the Skate class entering service in 1957. The Royal Navy's first nuclear fleet submarine was HMS Dreadnought which by using an American reactor entered service in 1963. The first all-British nuclear submarines were the two Valiant class submarines.

The US Navy (USN) submarine fleet has been all-nuclear powered for over two decades. 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, ARA General Belgrano was sunk by torpedoes fired by the Royal Navy fleet submarine HMS Conqueror (S48). 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 (limited more by the crew than the boat), and higher speed. Unlike most SSKs, SSNs do not have to surface periodically for air, which would compromise their stealth. These considerations are less significant for modern conventional submarines: LOX and Stirling engine powered vessels can cruise underwater for up to a week and are significantly quieter than nuclear submarines, since they do not need to run the powerful (and noisy) pumps associated with the cooling circuits of pressurized water reactors.

The main disadvantages of an SSN are the technological challenges and huge expense of building, refuelling and maintaining a nuclear power plant. Nuclear submarines are also a political problem, 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:
 * United States Navy
 * French Navy
 * People's Liberation Army Navy of China
 * Royal Navy of the United Kingdom
 * Russian Navy
 * Indian Navy

United States Navy

 * Los Angeles (SSN-688) (some have been retired)
 * Seawolf (SSN-21)
 * Virginia (SSN-774)

Royal Navy
Known as "fleet submarines" in the RN


 * Trafalgar-class submarine - 6 in service out of 7 built
 * Astute-class submarine - 2 in service out of 7 ordered

Russian Navy

 * Victor III class submarine
 * Sierra I and Sierra II class submarines
 * Akula class submarine
 * Yasen class submarine - in development

French Navy

 * Rubis-class submarine
 * Barracuda class submarine - in development

People's Liberation Army Navy

 * Han class submarine (Type 091)
 * Type 093 submarine
 * Type 095 submarine - in development

Indian Navy

 * Akula class submarine

Royal Navy

 * HMS Dreadnought - the Royal Navy's first nuclear-powered fleet submarine 1963-1980
 * Valiant class submarine - 2 submarines in service 1966 1994
 * Churchill class submarine - 3 submarines in service 1970 - 1992
 * Swiftsure class submarine - 6 submarines 1973-2010

Russian/Soviet Navy

 * November class
 * Mike class - the ill-fated K-278 Komsomolets
 * Alfa class

United States Navy

 * USS Nautilus (SSN-571) (unique)
 * USS Seawolf (SSN-575) (unique)
 * Skate (SSN-578)
 * Skipjack (SSN-585)
 * USS Triton (SSN-586) (unique)
 * USS Halibut (SSN-587)
 * USS Thresher/Permit (SSN-593)
 * USS Tullibee (SSN-597) (unique)
 * Sturgeon (SSN-637)
 * USS Narwhal (SSN-671) (unique)
 * USS Glenard P. Lipscomb (SSN-685) (unique)