Dynamic simulation and verification of pressurizer based on nonequilibrium multi-region model

A code (NEP-MR) was developed for dynamic simulation of electrical heating pressurizer. Nonequilibrium multi-region model was considered and Gear method was adopted for numerical solution. The calculation results were compared with the test results of transient loss of load from 74 MW and 105 MW for Shippingport Nuclear Power Plant in America, and the trend showed a good agreement. The NEP-MR program can well reflect the thermal stratification phenomenon of control volumes in the pressurizer during transient loss of load process. At the moment of the pressurizer sprayer on and off, a flow rate jump phenomenon occurrs at the interfaces between volumes of vapor and liquid phase. The computed results prove the applicability and accuracy of nonequilibrium multi-region model and the program simulation.