The graphic below shows a pressurizer and its parts. The pressurizer regulates system pressure during variations in reactor coolant temperature and volume due to normal or unexpected changes in power output. The table below describes how the pressurizer regulates primary system pressure. Function Process Increase water temperature and pressure 1. Heaters in the lower end of the pressurizer increase water temperature and pressure.
Steam collects at the top of the pressurizer.
The steam exerts pressure on the reactor coolant beneath it. Decrease water temperature and pressure 1. The spray condenses steam back to water to reduce system pressure. Other safety features The table below describes other pressurizer safety features. Vent steam to a pressurizer relief tank if the pressure in the vessel exceeds a programmed maximum.