Development and verification of the mathematical modeling for gas-pressurizer system

Abstract

The accurate simulation of the dynamic characteristics of a pressure control system (Pressurizer) has a significant role in industrial applications, especially in the nuclear industry. In this paper, the pressurizer (PRZ) used in the water process engineering and nuclear reactors are classified into three categories: Steam PRZ, Steam-gas PRZ, and Gas PRZ. Nowadays, steam PRZs are typically used in pressurized nuclear reactors. In return, due to the proper characteristics of gas PRZ, these systems are expected to be a suitable alternative for use in Small Modular Reactors (SMRs) and even other pressurized research reactors. However, there is a lack of literature about the context of the gas PRZ. As one of the works about gas PRZ, this paper suggests a mathematical model to predict the gas PRZ’s dynamic behavior and implements this framework in MATLAB software. This proposed model's performance has been evaluated and verified for two pressurized water test facilities, including the University of Wisconsin High-Pressure Critical Heat Flux (WHPCHF) facility and the Idaho National Laboratory (INL) facility as the base loops. Throughout this analysis, the suggested model performance during the temperature and pressure transient conditions are compared with the results of the PRZ modeled in the Aspen HYSYS software for both base loops. Also, the diagrams of PRZ mass inventory changes, liquid level inside the PRZ and pressure in both different test loops with different non-condensable gases (nitrogen and argon) show that the proposed mathematical model is in good agreement with the results by Aspen HYSYS. Therefore, this proposed mathematical model can suitably model the dynamic behavior of a gas PRZ. The proposed model can also be used to simulate gas PRZs control systems and the extension in studying about the modeling of these PRZs.