The pressurizer serves to establish and control the operating pressure within the primary heat transport system. This is achieved by electrical heaters that raise the saturation pressure of the pressurizer’s water and steam inventory to the appropriate value.
This unit is a tall, cylindrical tank typically connected at the bottom to a reactor coolant loop hot leg through 10 in. (254 mm) diameter surge line piping. Spray is introduced near the top of the pressurizer through a nozzle and 4 in. (102 mm) diameter line from a cold leg.
Three replaceable heater bundles are installed over the lower portion of the pressurizer.
Pressure relief devices are mounted at the top of the unit; these include two code safety valves and the power operated relief valve (PORV).