How does a nuclear-powered submarine use a reactor to turn its propeller?

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nuclear engineering Installation of the dome of a containment structure at the Taishan nuclear power plant, Guangdong province, southern China, 2012.

A nuclear-powered submarine generates propulsion through a process that converts nuclear energy into mechanical motion. The system relies on a nuclear reactor to produce heat via nuclear fission.1

The process functions as follows:

Primary Loop: Water circulates through the reactor core, absorbing heat generated by the fission of uranium. This water is kept under high pressure to prevent it from boiling.1
Heat Exchange: The heated primary water flows through a heat exchanger, where it transfers its thermal energy to a separate secondary water circuit.1
Steam Generation: The heat causes the water in the secondary loop to turn into steam.1
Mechanical Drive: This high-pressure steam is directed into a steam turbine, which spins as the steam passes through it. The turbine is connected to the propeller, providing the necessary mechanical power to drive the submarine through the water.1

This closed-loop design ensures that the radioactive water from the primary loop remains isolated from the rest of the power plant.1