Naval Nuclear Propulsion Plant

The propulsion plants of the earlier SKIPJACK, PERMIT, STURGEON, LOS ANGELES, SEAWOLF and VIRGINIA  class nuclear-powered attack submarines, as well as GEORGE WASHINGTON, ETHAN ALLEN, LAFAYETTE, BENJAMIN FRANKLIN and OHIO class fleet ballistic missile submarines, and the nuclear-powered ships of the surface fleet are based upon the use of a nuclear reactor to provide heat.  The heat comes from the fissioning of a nuclear fuel contained within the reator.  Since the fissioning process also produces radiation, shields are placed around the reactor so that the crew is protected.

Basic Description of Naval Nuclear Propulsion Plant

The nuclear propulsion plant in the ship uses a pressurized water reactor design which has two basic systems: 1. the primary system; and, 2. the secondary system.  The primary system circulates ordinary water and consists of the reactor, piping loops, pumps and steam generators.  The heat produced in the reactor is transferred to the water under high pressure so it does not boil. The water is pumped through the steam generators and back into the reactor for reheating.  In the steam generators, the heat from the water in the primary system is transferred to the secondary system to create steam. 

The secondary system is isolated from the primary system so that the water in the two systems does not intermix.  In the secondary system, the steam flows from the seam generators to drive the turbine generators, which simply supply the ship with electrictiy, and to the main propulsion turbines, which drive the propeller.  After passing through the turbines, the steam is condensed back into water which is fed back to the steam generators by the feed pumps.  Thus, both the primary and secondary systems are closed systems where water is recirculated and reused.  There is no step in the generation of this power which requires the presence of air or oxygen.  This allows the ship to operate completely independent from the earth's atmosphere for extended periods of time.