Nuclear boilers

Schematic diagram of a pressurized water nuclear reactor and steam generators

Nuclear boilers have been used, without commercial success, in a few merchant ships,
e.g. the US-built NS Savannah, the German-built NS Otto Hahn and the Russian-built
NS Sevmorput.   Nowadays marine nuclear boilers are used in large navy ships and
icebreakers serving in Arctic waters.

1. Feedwater pump
   
2. Feedwater line
   
3. Steam generator
   Radiation shielding is not needed on this secondary cycle.
4. Downcomer
   The water is directed downward and flows along a wrapper sheet.
5. Riser
   The water is directed upwards inside the wrapper sheet to flow along the steam generator tubes.
6. Steam Separators
   The steam separator removes the remaining moisture from the outgoing steam.
7. Moisture Separators
   Moisture separator. Removes water droplets and moisture from the steam.
8. Reactor Coolant Pump
   Part of the Primary Loop
9. Primary Loop
   The function of the primary loop is to transfer the heat from the reactor to the steam generator. The primary loop is a Reactor Cooling System.
10. Relief valve
    Releses the pressure in case of overpressure.
11. Spryer
    Cooling down the pressurizer and reduces the pressure.
12. Pressurizer
    Pressurizes the water to prevent it from boiling.
13. Heater
    Heating the Pressurizer and increases the pressure.
14. Coolant
    Pressurized water.
15. Fuel Rods
    Fissionable material, Uranium.
16. Reactor vessel
    The reactor vessel that contains the nuclear fuel is the central component of the reactor coolant system. All internal surfaces of the vessel are clad with stainless steel to avoid corrosion. The reactor vessel is radiation shielded.
17. Control rods
    Absorb neutrons and slow down the reaction. Boron or Cadmium rods
18. Control rods drive mechanism
    Adjusting the energy output of the reactor.
19. Steam outlet
    Steam to turbines and other consumers.