Accident analysis of supercritical water reactor in startup

To analyze the typical accident characteristics during the startup of a supercritical water reactor(SCWR), the entire system model of the CSR1000 was established with the analysis code SCTRAN, based on models of the high performance light water reactor (HPLWR) steam cycle, SCWR circulation startup loop and passive safety systems. According to the sequence of the accident without a safety system and the trigger signal of the accident safety system under the rated condition, the new trigger signal during the startup is designed. "Loss of coolant flow accident (LOFA)", "loss of coolant accident (LOCA)" and "uncontrolled CR withdrawal accident" under startup procedure were calculated with the new trigger signal. The calculation results show that: the new trigger signal can ensure the effective and timely response of the safety system and ensure the safety of the reactor during the startup process. The cladding surface temperature of the reactor reaches the maximum value at the end of the fourth stage of startup procedure with LOCA. The temperature value is 850 ℃, which stays below the safety criterion with a large margin. (author)