Abstract
The natural circulation operational characteristics of passive residual heat removal system (PRHRS) in secondary loop under ocean conditions were simulated. Mathematical models of PRHRS natural circulation loop under ocean conditions were established and a simulation program was developed. The flow rate, pressure of steam generator, drivinghead and additional pressure drop of PRHRS under ocean and motionless conditions were investigated and compared. The results indicated that natural circulation capacity of PRHRS decreases under ocean conditions. Rolling has the biggest impact on this system among rolling, pitching and yawing. Average flow rate and driving head decrease by increasing rolling amplitude but remains unchanged with the change of rolling period, while average additional pressure drop in one period is zero. The flow rate fluctuates more severely under conditions of short rolling period or large amplitude. Moreover, it is found that the pressure of steam generator decreases more slowly under ocean conditions than that under motionless condition due to flow rate fluctuation and reduction.
