Safety valves Safety valves open automatically to release steam and prevent overpressure in the system in the event of an unexpected shutdown. How the secondary system works The graphic below depicts how the secondary system works. The table below describes how the secondary system works to transform heat from the primary system into steam and electricity. Stage Description 1 Heat from the primary system is transferred to the main steam system in the steam generators. 3 from the secondary system flows on the outside of these tubes.
Heat is transferred from the tubes, turning the water in the secondary system to steam.
4 steam then flows through steam separators and dryers located in the top of each steam generator. Moisture removed by steam separators and dryers is recirculated within the steam generator. 5 exiting the steam generator, steam flows through a piping system outside the reactor containment building. Valves located throughout this system regulate the pressure and flow of steam during plant operations. 6 flows through the piping system to the turbine blades.