The steam generator passive heat removal system (SG-PHRS) for the V-407 reactor does not require a power supply and is designed to remove the decay heat in case of a non-LOCA. It also supports the emergency core cooling function in case of a LOCA. The reactor coolant system and passive heat removal equipment arrangement provides heat removal from the core following reactor shutdown via steam generator heat transfer to the tanks of chemically demineralized water (CWT) outside the containment and further to the atmosphere by natural circulation as shown in Figure XII-4. Reactor power that can be removed from the core by coolant natural circulation is about 10% of the nominal value, which ensures a reliable residual heat removal. In case of a non-LOCA the decay heat is removed by coolant natural circulation to steam generator boiler water. The steam generated comes into the passive heat removal system where steam is condensed on the internal surface of the tubes that are cooled on the outside surface by the water stored in the demineralized water tank. These tanks are stored outside the containment. The water inventory in this tank is sufficient for the long term heat removal (at least 24 hours) and can be replenished if necessary from an external source.

FIG. XII-4. Passive heat removal for non-LOCAs.