From HomoExcelsior

1. Emergency core cooling system. A redundant system used to rapidly drop the temperature of a nuclear reactor's core. ECCS is designed for emergency core cooling in case of main circulation, feedwater and steam pipe rupture, and water supply to the separator drums by ECCS pumps in case of emergency trip of feedwater pumps and emergency feedwater pumps. ECCS pressurized tanks and pumps are used as sources for water supply to the reactor. ECCS pressurized tanks and FWPs ensure water supply to the reactor during the first two minutes since the start of an accident, whilst pumps ensure long-term water supply. In case of feedwater or steam pipe break the pressure in the leak-tight compartments rises, the level in the separator drums of the affected half of the core drops, pressure differential between the MCP pressure header and separators decreases. The above signals cause ECCS actuation.

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