Large-break LOCA analysis of CSR1000

Abstract Large-break loss of coolant accident (LBLOCA) analysis of China Supercritical water-cooled Reactor (CSR1000) has been carried out to evaluate its safety system capability. Analysis results indicate that one significant feature of cold-leg LBLOCA is the reverse-flow which occurs in the core due to the break blowdonwn. The reverse-flow drives the pseudo steam into the core and results in the core heat transfer deterioration which induces a quick increasing of the cladding temperature. After the actuation of the automatic depressurization system (ADS) valves, the core coolant forward-flow recovers and the excessive core heat-up is mitigated. The high feed water tank (HFT) provides enough coolant supply to give the low pressure injection system (LPSI) more response time. After the blowdown phase, the core can be re-flooded by LPSI system. The calculated maximum cladding temperature keeps below the safety criterion.