The function of the reactor coolant pump (referred to as the main pump) is to force the coolant to form a forced circulation, thereby transferring the heat generated in the reactor to the steam generator to generate steam and drive the turbine to do work.
The reactor coolant pump is one of the key equipment of the PWR nuclear power plant and the only rotary machinery in the reactor cooling system. The basic requirements are:
1) Being able to work safely and reliably under unmanned conditions for a long time;
2) Easy to repair, the auxiliary system is simple;
3) The main pump rotating assembly should be able to provide sufficient moment of inertia to provide sufficient flow using the main pump idling in the event of a plant-wide power failure to allow the reactor core to be properly cooled;
4) Austenitic stainless steel, or other materials with equivalent corrosion resistance, are required for the surface material of the overcurrent parts;
5) Leakage with radioactive coolant should be less.
Reactor coolant pumps can be divided into two broad categories: canned pumps and shaft seal pumps.
Since the main pump uses high temperature, high pressure, and radioactive water as the working medium, the early pressurized water reactor power unit used a canned pump to solve the sealing problem. The shielded pump is also called a non-filled pump. The pump impeller and the motor rotor are integrated into one and are housed in the same sealed housing, thus eliminating the possibility of coolant leakage. This type of pump has long been used on nuclear-powered ships and has proven to be safe and reliable.
