Experimental Research of Natural Circulation Characteristics in Secondary Side Passive Residual Heat Removal System

The natural circulation characteristics in the secondary side passive residual heat removal system is experimentally studied on ESPRIT（Emergency Secondary Passive Residual heat removal system Integral Test facility）. The experiment is carried out under prototypical, elevated power and elevated resistance conditions, and the response characteristics and operation capability were studied under station blackout scenario. The test data reveal that the design volume of the cooling water tank satisfies the heat removal demand in 72 hours. The heat sink possesses sufficient cooling capability after the power is elevated by 6%. The system pressure in elevated resistance condition is always higher than that of the prototypical condition. The natural circulation always remains and the system temperature and pressure keep decreasing in elevated resistance condition.