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Thursday, September 12, 2013

Nuclear submarine

From Wikipedia, the free encyclopedia

This article is about submarines powered by nuclear energy. For submarines carrying nuclear weapons, see Ballistic missile submarine.
A nuclear submarine is a submarine powered by a nuclear reactor. The performance advantages of nuclear submarines over "conventional" (typically diesel-electric) submarines are considerable: nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines; the large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long durations; and the long interval between refuellings grants a range limited only by consumables such as food. Current generations of nuclear submarines never need to be refueled throughout their 25-year lifespans.[1] Conversely, the limited power stored in electric batteries means that even the most advanced conventional submarine can only remain submerged for a few days at slow speed, and only a few hours at top speed; recent advances in air-independent propulsion have eroded this disadvantage somewhat. The high cost of nuclear technology means that relatively few states have fielded nuclear submarines. Some of the most serious nuclear and radiation accidents ever to occur have involved Soviet nuclear submarine mishaps.[2][3] Ballistic missile submarines, which carry nuclear weapons, are one of the types of nuclear submarines. However, most nuclear submarines serve other purposes. That is the case of some attack submarines.

History

USS Nautilus (SSN-571), the first nuclear-powered submarine.
The idea for a nuclear-powered submarine was first proposed by the Naval Research Laboratory's Ross Gunn[4] in 1939.
The United States launched the USS Nautilus, the first nuclear submarine, in 1954.[5] Nautilus could remain underwater for up to four months without resurfacing.
Construction of the Nautilus was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers at the Naval Reactors Branch of the Atomic Energy Commission. In July 1951 the U.S. Congress authorized construction of the world's first nuclear-powered submarine, under the leadership of Captain Hyman G. Rickover, USN.[6]
The Westinghouse Corporation was assigned to build its reactor. After the submarine was completed, Mamie Eisenhower broke the traditional bottle of champagne on Nautilus' bow. On 17 January 1955, it began its sea trials after leaving its dock in Groton, Connecticut. The submarine was 320 feet (98 m) long, and cost about $55 million.
The Soviet Union soon followed the United States in developing nuclear-powered submarines in the 1950s. Stimulated by the U.S. development of the Nautilus, Soviet work on nuclear propulsion reactors began in the early 1950s at the Institute of Physics and Power Engineering, in Obninsk, under Anatoliy P. Alexandrov, later to become head of the Kurchatov Institute. In 1956, the first Soviet propulsion reactor designed by his team began operational testing. Meanwhile, a design team under Vladimir N. Peregudov worked on the vessel that would house the reactor.
After overcoming many obstacles, including steam generation problems, radiation leaks, and other difficulties, the first nuclear submarine based on these combined efforts entered service in the Soviet Navy in 1958.[7][unreliable source?]
The VMF Typhoon class submarine, is nuclear-powered and the world's largest-displacement submarine.[8]
At the height of the Cold War, approximately five to ten nuclear submarines were being commissioned from each of the four Soviet submarine yards (Sevmash in Severodvinsk, Admiralteyskiye Verfi in St. Petersburg, Krasnoye Sormovo in Nizhny Novgorod, and Amurskiy Zavod in Komsomolsk-on-Amur). From the late 1950s through the end of 1997, the Soviet Union, and later Russia, built a total of 245 nuclear submarines, more than all other nations combined.[9]
Today, six countries deploy some form of nuclear-powered strategic submarines: the United States, Russia, France, the United Kingdom, People's Republic of China, and India.[10] Several other countries, including Argentina and Brazil,[11][12] have ongoing projects in different phases to build nuclear-powered submarines.
In the United Kingdom, all former and current nuclear submarines for their British Royal Navy (with the exception of three: HMS Conqueror, HMS Renown and HMS Revenge) have been constructed in Barrow-in-Furness (at BAE Systems Submarine Solutions or its predecessor VSEL) where construction of nuclear submarines continues. Conqueror is the only nuclear-powered submarine ever to have engaged an enemy ship with torpedoes, sinking the cruiser ARA General Belgrano with two Mark 8 torpedoes during the 1982 Falklands War.[note 1]

Technology

HMS Astute, an advanced nuclear-powered attack submarine.[13]
The main difference between conventional submarines and nuclear submarines is the power generation system. Nuclear submarines employ nuclear reactors for this task. They either generate electricity that powers electric motors connected to the propeller shaft or rely on the reactor heat to produce steam that drives steam turbines (cf. nuclear marine propulsion). Reactors used in submarines typically use highly enriched fuel (often greater than 20%) to enable them to deliver a large amount of power from a smaller reactor and operate longer between refuelings – which are difficult due to the reactor's position within the submarine's pressure hull.
The nuclear reactor also supplies power to the submarine's other subsystems, such as for maintenance of air quality, fresh water production by distilling salt water from the ocean, temperature regulation, etc. All naval nuclear reactors currently in use are operated with diesel generators as a backup power system. These engines are able to provide emergency electrical power for reactor decay heat removal, as well as enough electric power to supply an emergency propulsion mechanism. Submarines may carry nuclear fuel for up to 30 years of operation. The only resource that limits the time underwater is the food supply for the crew and maintenance of the vessel.
The stealth weakness of nuclear submarines is the need to cool the reactor even when the submarine is not moving; about 70% of the reactor output heat is dissipated into the sea water. This leaves a "thermal wake", a plume of warm water of lower density which ascends to the sea surface and creates a "thermal scar" that is observable by thermal imaging systems, e.g., FLIR.[14] Another problem is that the reactor is always running, creating steam noise, which can be heard on SONAR, and the reactor pump (used to circulate reactor coolant), also creates noise, as opposed to a conventional submarine, which can move about on incredibly silent electric motors.[citation needed]

Lineage

United States United States Navy

Decommissioned

Operational

Under development

Soviet UnionSoviet / RussiaRussian Navy

Decommissioned

Operational submarines

Under development

United Kingdom Royal Navy of the United Kingdom

Decommissioned

Operational

Under development

France French Navy

Decommissioned

Operational

Under development

China People's Liberation Army Navy of the People's Republic of China

Operational

Under development

India Indian Navy

Commissioned

Under development

Accidents

See also: List of sunken nuclear submarines

Reactor accidents aboard nuclear submarines

Some of the most serious nuclear and radiation accidents by death toll in the world have involved nuclear submarine mishaps. To-date, all of these were units of the former Soviet Union.[2][3][16] Reactor accidents that resulted in core damage and release of radioactivity from nuclear-powered submarines include:
  • K-8, 1960, loss-of-coolant accident; substantial radioactivity released.[17]
  • K-14, 1961, reactor compartment replaced due to unspecified "breakdown of reactor protection systems."
  • K-19, 1961, loss-of-coolant accident resulting in 8 deaths and more than 30 other people being over-exposed to radiation.[18] The events on board the submarine are dramatized by the film K-19: The Widowmaker.
  • K-11, 1965, both reactors damaged during refueling while lifting the reactor vessel heads; reactor compartments scuttled off the east coast of Novaya Zemlya in the Kara Sea in 1966.
  • K-27, 1968, experienced reactor core damage to one of its liquid metal (lead-bismuth) cooled VT-1 reactors, resulting in 9 fatalities and 83 other injuries; scuttled in the Kara Sea in 1982.[2]
  • K-140, 1968, reactor damaged following an uncontrolled, automatic increase in power during shipyard work.[19]
  • K-429, 1970, an uncontrolled start up of the ship's reactor led to a fire and the release of radioactivity[19]
  • K-116, 1970, loss-of-coolant accident in the port reactor; substantial radioactivity released.
  • K-64, 1972, failure of the first Alpha-class liquid-metal cooled reactor; reactor compartment scrapped.
  • K-222, 1980, Papa-class submarine had a reactor accident during maintenance in the shipyard while the ship's naval crew had left for lunch.[19]
  • K-123, 1982, Alpha-class submarine reactor core damaged by liquid-metal coolant leak; the sub was forced out of commission for eight years.[19][20]
  • K-431, 1985, a reactor accident while refueling resulted in 10 fatalities and 49 other people suffered radiation injuries.[3]
  • K-219, 1986, suffered an explosion and fire in a missile tube, eventually leading to a reactor accident; a 20-year old enlisted seaman, Sergei Preminin, sacrificed his life to secure one of the onboard reactors. The submarine sank three days later.
  • K-192, 1989, loss-of-coolant accident due to a break in the starboard reactor loop; reclassified from K-131.

Other major accidents and sinkings of nuclear submarines

  • USS Thresher (SSN-593), 1963, was lost during deep diving tests; later investigation concluded that failure of a brazed pipe joint and ice formation in the ballast blow valves prevented surfacing. The accident motivated a number of safety changes to the U.S. fleet.
  • K-3, 1967, the first Soviet nuclear submarine, a fire associated with the hydraulic system killed 39 sailors.
  • USS Scorpion (SSN-589), 1968, lost at sea, evidently due to implosion upon sinking. What caused Scorpion to descend to its crush depth is not known.
  • USS Guitarro (SSN-665), 1969, sank while pier-side in shipyard due to improper ballasting.
  • K-8, 1970, fire and a towing accident resulted in the boat's sinking and loss of all 52 crewmen remaining aboard.
  • K-56, 1973, collision with another Soviet vessel led to flooding of the battery well and many crew deaths due to chlorine gas.
  • K-429, 1983, sub survivably sank to the ocean bottom due to flooding from improper rig-for-dive and shipyard errors; 16 crewmen were killed.
  • K-278 Komsomolets, 1989, Soviet submarine sank in Barents Sea due to a fire.
  • K-141 Kursk, 2000, the generally accepted theory is that a leak of hydrogen peroxide in the forward torpedo room led to the detonation of a torpedo warhead, which in turn triggered the explosion of half a dozen other warheads about two minutes later.
  • Ehime Maru & USS Greeneville, 2001, the American submarine surfaced underneath the Japanese training vessel. Nine Japanese were killed when their ship sank as a result of the collision.[21]
  • K-159, 2003, sank in the Barents Sea while being towed to be scrapped, killing nine crewmen.
  • USS San Francisco (SSN-711), 2005, collided with a seamount in the Pacific Ocean. A crew member was killed and 23 others were injured.
  • USS Miami (SSN-755), 2012, the submarine's forward compartment was destroyed by an arsonist-set fire while in shipyard, causing an estimated $500 million in damage.

See also

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