An AP600/1000 Sump is a safety feature in nuclear power plants that serves as a collection point for coolant in the event of a Loss of Coolant Accident (LOCA). It is a large, reinforced pool of water located at the bottom of the containment building that is used to collect and cool any leaked or spilled coolant from the reactor core or other systems.
The In-containment Refueling Water Storage Tank (IRWST) is a crucial component of the AP600/1000 Sump. It provides a reserve source of water for cooling the reactor core and other systems in the event of a LOCA. It also serves as a backup water source for refueling the reactor during shutdowns.
The Reactor Pressure Vessel (RPV) is the vessel that contains the nuclear fuel and generates heat to produce steam for electricity. In the event of a LOCA, the RPV releases coolant into the containment building, which then flows down into the AP600/1000 Sump. The RPV also has connections to the IRWST, allowing for additional coolant to be added if needed.
The coolant collected in the AP600/1000 Sump is continuously circulated through the Emergency Core Cooling System (ECCS) to cool the reactor core and other systems. It is also filtered to remove any debris or particles that may have been released during the LOCA. Once the reactor is stabilized, the coolant is returned to the RPV for normal operation.
The AP600/1000 Sump is designed to provide a safety net in the event of a LOCA, preventing damage to the reactor core and other systems. By collecting and cooling the leaked coolant, it helps to maintain the integrity of the containment building and prevent the release of radioactive materials into the environment. It also allows for operators to safely shut down the reactor and initiate emergency cooling measures to prevent a meltdown.