How does a nuclear submarine's reactor work and how long can it stay submerged?

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1. 1

   Nuclear marine propulsion (Wikipedia)

   WikipediaPublished Oct 15, 2026Checked Oct 17, 2026

   “Nuclear marine propulsion is propulsion of a ship or submarine with heat provided by a nuclear reactor. The power plant heats water to produce steam for a turbine used to turn the ship's propeller through a gearbox or through an electric generator and motor. Nuclear propulsion is used primarily within naval warships such as nuclear submarines and supercarriers. A small number of experimental civil nuclear ships have been built. Compared to oil- or coal-fuelled ships, nuclear propulsion offers the advantage of very long intervals of operation before refueling. All the fuel is contained within the nuclear reactor, so no cargo or supplies space is taken up by fuel, nor is space taken up by exhaust stacks or combustion air intakes. The low fuel cost is offset by high operating costs and investment in infrastructure, however: nearly all nuclear-powered vessels are military, though several nuclear-powered icebreakers and cargo ships have been built.”

2. 2

   A complicated way of boiling water: nuclear safety in water history.

   Water history (Evens)Published Nov 17, 2020Checked Oct 17, 2026

   “Water and nuclear reactors are much closer intertwined than usually perceived. First, water is the source of the steam that drives the turbines of most nuclear power plants around the world. Next to generating electricity, water is the key to preventing accidents in nuclear plants. As uranium keeps on generating heat when the power plant is turned off, its core needs to be cooled continuously. This crucial connection between water and nuclear is focus of the paper. Nuclear safety will appear as relying heavily on earlier knowledge, institutions, and regulatory frameworks, which were related to water. The three parts of this article discuss technologies, actors and risks of nuclear power. Studying water as a resource in a much broader sense than being boiled for steam shows how determining water is to make nuclear power function. As this paper is part of a special issue, Water History in the time of COVID-19, it has undergone modified peer review.”

3. 3

   Status of the sunken nuclear submarine Komsomolets in the Norwegian Sea.

   Proceedings of the National Academy of Sciences of the United States of America (Gwynn et al.)Published Mar 23, 2026Checked Oct 17, 2026

   “It was confirmed that releases from the reactor were still occurring, but not continuously, with maximum activity concentrations of 90Sr and 137Cs that were 400,000 and 800,000 times higher, respectively, than typical levels of these radionuclides in the Norwegian Sea. Elevated levels of 239Pu, 240Pu, and 236U were also detected in the releases from the reactor, with atom ratios of 240Pu/239Pu and 236U/239Pu that indicate that the nuclear fuel in the reactor is corroding. Despite that releases from the reactor have occurred for over 30 y, there is little evidence of any accumulation of radionuclides in the near environment around the submarine as the released radionuclides appear to be rapidly diluted in the surrounding seawater. Releases from the reactor in Komsomolets can be expected to continue, so further investigations should be carried out to determine the mechanisms behind the observed releases, the corrosion processes that are occurring within the reactor and the implications of these for further releases and the fate of the remaining nuclear material in the reactor.”