Nuclear marine propulsion
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/* Civil vessels */ adding image of NS ''50 Years Since Victory'' (NS ''50 Let Podey'')
'''Nuclear marine propulsion''' is propulsion of a ship powered by a [[nuclear reactor]]. '''Naval nuclear propulsion''' is propulsion that specifically refers to naval warships (see [[Nuclear navy]]).
[[Image:Nuclear fuel element.jpg|thumb|right|A nuclear fuel element for the cargo ship [[NS Savannah|NS ''Savannah'']]. The element contains four bundles of 41 fuel rods. The uranium oxide is enriched to 4.2 and 4.6 percent of U-235]]
==Power plants==
Naval [[Nuclear reactor|reactors]] are of the [[Pressurized water reactor|pressurized water]], type, which differ from commercial reactors producing [[electricity]] in that:
*they have a high [[power density]] in a small volume; some run on low-enriched [[uranium]] (requiring frequent refuelings), others run on [[highly enriched uranium]] (>20% U-235, varying from over 96% in U.S. [[submarine]]s (They do not need to be refueled as often<ref>{{cite web|url=http://www.nti.org/e_research/e3_74.html|title=Global Submarine Proliferation: Emerging Trends and Problems|author=James Clay Moltz|publisher=[[NTI]]|date=March 2006|accessdate=2007-03-07}}</ref> and are quieter in operation from smaller core<ref>{{cite web|url=http://www.armscontrolwonk.com/1738/silence-is-highly-enriched-uranium|title=Silence is highly enriched uranium|date=December 13, 2007|author=James Acton|accessdate=2007-12-13}}</ref>) to between 30–40% in Russian submarines to lower levels in some others),
*the fuel is not UO<sub>2</sub> (Uranium Oxide) but a metal-[[zirconium]] alloy (circa 15% U with 93% enrichment, or more U with lower enrichment),
*the design enables a compact [[Reactor vessel|pressure vessel]] while maintaining [[Nuclear safety|safety]].
The long core life is enabled by the relatively high enrichment of the [[uranium]] and by incorporating a "burnable [[Nuclear poison|poison]]" in the cores which is progressively depleted as [[fission product]]s and [[minor actinides]] accumulate, leading to reduced [[fuel efficiency]]. The two effects cancel one another out. One of the technical difficulties is the creation of a fuel which will tolerate the very large amount of radiation damage. It is known that during use the properties of [[nuclear fuel]] change; it is quite possible for fuel to [[crack]] and for [[fission]] gas bubbles to form.
Long-term integrity of the compact [[Reactor vessel|reactor pressure vessel]] is maintained by providing an internal [[neutron]] shield. (This is in contrast to early [[Soviet Union|Soviet]] civil PWR designs where embrittlement occurs due to [[Neutron radiation|neutron bombardment]] of a very narrow [[Reactor vessel|pressure vessel]].)
Reactor sizes range up to [[1 E8 W|550]] [[MW]] in the larger submarines and surface ships. The French {{Sclass|Rubis|submarine|1}}s have a [[1 E7 W|48 MW]] reactor which needs no refueling for 30 years.
The [[Russian Navy|Russian]], [[United States Navy|U.S.]] and [[Royal Navy|British]] navies rely on [[steam turbine]] propulsion, while the French and Chinese use the turbine to generate electricity for propulsion ([[turbo-electric]] propulsion). Most Russian submarines as well as most American aircraft carriers since {{USS|Enterprise|CVN-65}} are powered by two reactors (although ''Enterprise'' has eight). U.S., British, French and Chinese submarines are powered by one.
Decommissioning nuclear-powered submarines has become a major task for US and Russian navies. After defuelling, U.S. practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste (see the [[Ship-Submarine recycling program]]). In Russia, the whole vessels, or the sealed reactor sections, typically remain stored afloat, although a new facility near Sayda Bay is beginning to provide storage in a concrete-floored facility on land for some submarines in the Far North.
Russia is well advanced with plans to build a [[Russian floating nuclear power station|floating nuclear power plant]] for their far eastern territories. The design has two 35 MWe units based on the [[KLT-40 reactor]] used in [[icebreaker]]s (with refueling every four years). Some Russian naval vessels have been used to supply electricity for domestic and industrial use in remote far eastern and Siberian towns.
==History==
Under the direction of [[Admiral]] [[Hyman G. Rickover]], the design, development and production of nuclear marine propulsion plants started in the [[USA]] in the 1940s, with the first test reactor being started up in [[1953]]. The first nuclear-powered submarine, {{USS|Nautilus|SSN-571}}, put to sea in [[1955]]. Much of the early development work on naval reactors was done at the [[Naval Reactor Facility]] on the campus of the [[Idaho National Laboratory]].
This marked the transition of submarines from slow underwater vessels to warships capable of sustaining 20-25 [[Knot (speed)|knot]]s (37-46 [[Kilometres per hour|km/h]]) submerged for many weeks.
''Nautilus'' led to the parallel development of further {{Sclass|Skate|submarine|2}}s, powered by single reactors, and a cruiser, {{USS|Long Beach|CGN-9|2}}, in [[1961]], powered by two reactors. The aircraft carrier ''Enterprise'', commissioned in 1962, was powered by eight reactor units in [[1960]]. ''Enterprise'' remains in service.
By 1962 the [[United States Navy]] had 26 nuclear submarines operational and 30 under construction. Nuclear power had revolutionized the Navy. The technology was shared with the [[United Kingdom]], while [[France|French]], [[Soviet Union|Soviet]], [[India]]n and [[China|Chinese]] developments proceeded separately.
After the ''Skate''-class vessels, reactor development proceeded and in the USA a single series of standardized designs was built by both [[Westinghouse Electric Corporation|Westinghouse]] and [[General Electric]], one reactor powering each vessel. [[Rolls-Royce plc|Rolls Royce]] built similar units for [[Royal Navy]] submarines and then developed the design further to the PWR-2 ([[pressurized water reactor]]).
The largest nuclear submarines ever built are the 26,500 tonne Russian {{Sclass|Typhoon|submarine|4}}.
==Civil vessels==
Development of [[List of civilian nuclear ships|nuclear merchant ships]] began in the 1950s, but has not generally been commercially successful. The US-built [[NS Savannah|NS ''Savannah'']], was commissioned in [[1962]] and decommissioned eight years later. It was a technical success, but not economically viable. The German-built [[Otto Hahn (ship)|''Otto Hahn'']] cargo ship and research facility sailed some 650,000 nautical miles on 126 voyages in 10 years without any technical problems.{{Fact|date=February 2007}} However, it proved too expensive to operate and was converted to diesel. The Japanese [[Mutsu (ship)|''Mutsu'']] was the third civil vessel. It was dogged by technical and political problems and was an embarrassing failure. All three vessels used reactors with low-enriched uranium fuel.
The fourth nuclear merchant ship, ''[[Sevmorput]]'', operates successfully in the specialised environment of the [[Northern Sea Route]].
[[Image:50 Let Pobedy.jpg|thumb|right|160px|When the [[Arktika class icebreaker|Arktika class]] [[NS 50 Years Since Victory|NS ''50 Let Podey'']] was put into service in 2007, she became world's largest icebreaker.]]
Nuclear propulsion has proven both technically and economically feasible for [[nuclear powered icebreaker]]s in the [[Soviet Union|Soviet]] [[Arctic]]. The power levels and energy required for icebreaking, coupled with refueling difficulties for other types of vessels, are significant factors. The [[Soviet icebreaker Lenin|Soviet icebreaker ''Lenin'']] was the world's first nuclear-powered surface vessel and remained in service for 30 years, though new reactors were fitted in 1970. It led to a series of larger icebreakers, the 23,500 [[Tonnage|ton]] {{Sclass|Arktika|icebreaker|4}}, launched from [[1975]]. These vessels have two reactors and are used in deep Arctic waters. [[Arktika (icebreaker)|NS ''Arktika'']] was the first surface vessel to reach the [[North Pole]].
For use in shallow waters such as estuaries and rivers, shallow-draft [[Taymyr (icebreaker)|''Taymyr'' class icebreakers]] with one reactor are being built in [[Finland]] and then fitted with their nuclear steam supply system in [[Russia]]. They are built to conform with international safety standards for nuclear vessels.
==Naval nuclear accidents==
===United States===
*{{USS|Thresher|SSN-593}} (sank, 129 killed)
*{{USS|Scorpion|SSN-589}} (sank, 99 killed)
:Both sank for reasons unrelated to their reactor plants and still lie on the [[Atlantic]] sea floor.
===Russian or Soviet===
*[[Komsomolets K-278]] (sank, 42 killed)
*[[Russian submarine K-141 Kursk|Kursk K-141]] '''(sank recently, 118 killed)'''
*[[Soviet submarine K-8|K-8]] ([[loss of coolant]]) (sank, 42 killed)
*[[Soviet submarine K-11|K-11]] (refueling [[Criticality accident|criticality]])
*[[K-19]] ([[loss of coolant]])
*[[Soviet submarine K-27|K-27]] (scuttled)
*[[Soviet submarine K-116|K-116]] (reactor accident)
*[[Soviet submarine K-122|K-122]] (reactor accident)
*[[Soviet submarine K-123|K-123]] ([[loss of coolant]])
*[[Soviet submarine K-140|K-140]] ([[Criticality accident|power excursion]])
*[[Soviet submarine K-159|K-159]] (radioactive discharge) '''(sank recently, 9 killed)'''
*[[Soviet submarine K-192|K-192]] ([[loss of coolant]])
*[[Soviet submarine K-219|K-219]] (sank after collision, 4 killed)
*[[Soviet submarine K-222|K-222]] ([[Criticality accident|uncontrolled startup]])
*[[Soviet submarine K-314|K-314]] (refueling [[Criticality accident|criticality]], 10 killed)
*[[Soviet submarine K-320|K-320]] ([[Criticality accident|uncontrolled startup]])
*[[Soviet submarine K-429|K-429]] '''(sank twice, 16 killed)'''
*[[Soviet submarine K-431|K-431]] (reactor accident)
*The Soviet [[Lenin (nuclear icebreaker)|icebreaker Lenin]] is also rumored to have had a nuclear accident.
:While not all of these were reactor accidents, since they happened to nuclear vessels, they have a major impact on nuclear marine propulsion and the global politics. Many of these accidents resulted in the sinking of the boat containing [[nuclear weapons]] on board, which remain there to this day.<ref>[http://www.johnstonsarchive.net/nuclear/radevents/ Database of radiological incidents and related events<!-- Bot generated title -->]</ref>
{{Seealso|List of military nuclear accidents}}
==See also==
* [[List of civilian nuclear ships]]
* [[List of United States Naval reactors]]
* [[Naval Reactors]]
* [[Nuclear navy]]
* [[United States Naval reactor]]
* [[Soviet naval reactor]]
* [[Army Nuclear Power Program]]
* [[Naval Nuclear Power School]]
* [[Echo class submarine]]
* [[Air-independent propulsion]]
==References==
<references/>
* AFP, 11 November 1998; in "Nuclear Submarines Provide Electricity for Siberian Town," FBIS-SOV-98-315, 11 November 1998.
* ITAR-TASS, 11 November 1998; in "Russian Nuclear Subs Supply Electricity to Town in Far East," FBIS-SOV-98-316, 12 November 1998.
* [http://news.bbc.co.uk/1/hi/northern_ireland/4132635.stm Harold Wilson's plan] BBC News story
==External links==
*[http://www.uic.com.au/ The Uranium Information Centre] provided some of the original material in this article.
* [http://nnptc.cnet.navy.mil/ Naval Nuclear Power Training Command]
* [http://gcaptain.com/maritime/blog/the-worlds-first-nuclear-merchant-ship-ns-savannah/ Nuclear Ships of the Merchant Navy]
{{Nuclear propulsion}}
[[Category:Marine propulsion]]
[[Category:Nuclear vehicle propulsion]]
[[Category:United States Navy nuclear ships|*]]
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