Editing Submarine (section)

====Nuclear power====
{{main|Nuclear submarine|Nuclear marine propulsion}}
[[File:Battery well of USS Nautilus.jpg|thumb|Battery well containing 126 cells on {{USS|Nautilus|SSN-571|6}}, the first nuclear-powered submarine]]

Steam power was resurrected in the 1950s with a nuclear-powered steam turbine driving a generator. By eliminating the need for atmospheric oxygen, the time that a submarine could remain submerged was limited only by its food stores, as breathing air was recycled and fresh water [[Distillation|distilled]] from seawater. More importantly, a nuclear submarine has unlimited range at top speed. This allows it to travel from its operating base to the combat zone in a much shorter time and makes it a far more difficult target for most anti-submarine weapons. Nuclear-powered submarines have a relatively small battery and diesel engine/generator powerplant for emergency use if the reactors must be shut down.

Nuclear power is now used in all large submarines, but due to the high cost and large size of nuclear reactors, smaller submarines still use diesel–electric propulsion. The ratio of larger to smaller submarines depends on strategic needs. The US Navy, [[French Navy]], and the British [[Royal Navy]] operate only [[nuclear submarine]]s,<ref name="Submarine Warfare">{{cite web|url=http://www.odu.edu/ao/hrnrotc/students/ns_courses/101odu/sumbmarine%20presentation%202005.ppt|archive-url=https://web.archive.org/web/20060908003323/http://www.odu.edu/ao/hrnrotc/students/ns_courses/101odu/sumbmarine%20presentation%202005.ppt|url-status=dead|archive-date=8 September 2006|title=Submarine Warfare|access-date=7 October 2006}}</ref><ref>{{cite web|url=http://www.nti.org/db/submarines/france/index.html|title=France Current Capabilities|publisher=Nti.org|access-date=18 April 2010}}</ref> which is explained by the need for distant operations. Other major operators rely on a mix of nuclear submarines for strategic purposes and diesel–electric submarines for defense. Most fleets have no nuclear submarines, due to the limited availability of nuclear power and submarine technology.

Diesel–electric submarines have a stealth advantage over their nuclear counterparts. Nuclear submarines generate noise from coolant pumps and turbo-machinery needed to operate the reactor, even at low power levels.<ref>{{cite book|last=Thompson|first=Roger|title=Lessons Not Learned|publisher=US Naval Institute Press|year=2007|isbn=978-1-59114-865-4|page=34}}</ref><ref>{{Cite book|last=Lee|first=T. W.|url=https://books.google.com/books?id=-nrZqzQs3jMC&q=Ohio+class+submarine+noise&pg=PA343|title=Military Technologies of the World [2 volumes]|date=30 December 2008|publisher=ABC-CLIO|isbn=978-0-275-99536-2|pages=344|language=en}}</ref> Some nuclear submarines such as the American {{sclass|Ohio|submarine|4}} can operate with their reactor coolant pumps secured, making them quieter than electric subs.{{Citation needed|date=April 2020}} A conventional submarine operating on batteries is almost completely silent, the only noise coming from the shaft bearings, propeller, and flow noise around the hull, all of which stops when the sub hovers in mid-water to listen, leaving only the noise from crew activity. Commercial submarines usually rely only on batteries, since they operate in conjunction with a mother ship.

Several [[nuclear and radiation accidents by death toll|serious nuclear and radiation accidents]] have involved nuclear submarine mishaps.<ref name=johnston2007/><ref name=timenuke/> The {{ship|Soviet submarine|K-19}} reactor accident in 1961 resulted in 8 deaths and more than 30 other people were over-exposed to radiation.<ref name=rad>[http://www.iaea.org/Publications/Magazines/Bulletin/Bull413/article1.pdf Strengthening the Safety of Radiation Sources] {{webarchive|url=https://web.archive.org/web/20090326181428/http://www.iaea.org/Publications/Magazines/Bulletin/Bull413/article1.pdf |date=26 March 2009 }} p. 14</ref> The {{ship|Soviet submarine|K-27}} reactor accident in 1968 resulted in 9 fatalities and 83 other injuries.<ref name=johnston2007>{{cite web|url=http://www.johnstonsarchive.net/nuclear/radevents/radevents1.html|title=Deadliest radiation accidents and other events causing radiation casualties|author=Johnston, Robert|date=23 September 2007|publisher=Database of Radiological Incidents and Related Events}}</ref> The {{ship|Soviet submarine|K-431}} accident in 1985 resulted in 10 fatalities and 49 other radiation injuries.<ref name=timenuke>{{cite magazine|url=http://www.time.com/time/photogallery/0,29307,1887705,00.html|archive-url=https://web.archive.org/web/20090328130544/http://www.time.com/time/photogallery/0,29307,1887705,00.html|url-status=dead|archive-date=28 March 2009|title=The Worst Nuclear Disasters|magazine=[[Time (magazine)|Time]]|access-date=1 April 2015|date=25 March 2009}}</ref>