Simulation research on passive safety injection system of marine nuclear power plant based on compressed gas

Abstract

In case of a large or medium LOCA accident of marine nuclear power plant, the loop pressure drops rapidly. In case of power failure of the whole ship at this time, the active safety injection system will lose its function because the safety injection pump needs AC power, and the core is at risk of melting. A passive marine safety injection system based on high-pressure compressed gas is designed for the superposition of large and medium LOCA accidents and the whole ship's power failure accidents, including the safety injection subsystem of medium and low pressure and the safety injection subsystem of recirculation. The energy required for safety injection is provided by the potential energy of compressed gas, the pressure head is provided by the technology of gas-liquid booster pump, and the collection signals and valves are controlled by the technology of intelligent fluid control unit with small power consumption. The power supply used in the system is provided by DC 24 V battery. The mathematical and physical models of accumulator, gas storage tank, gas-liquid booster pump, reactor body and its pipeline are established for the designed passive safety injection system. The operation and safety characteristics of medium pressure safety injection, low pressure safety injection and recycling safety injection under LOCA accident conditions are simulated. The safety injection time and flow rate of three safety injection pressures are simulated by medium pressure safety injection, the safety injection time and peak temperature are simulated by low pressure safety injection, and the pressure and system temperature are simulated by recirculation safety injection. The simulation results show that the marine passive safety injection system designed under LOCA accident conditions can meet the requirements of core cooling.