Study of Steam Hammer in the Main Steam System

Abstract

The main steam system plays an important role to transfer the saturated steam generated from the steam generator to the main turbine and other steam consumed devices in a pressurized water reactor. During the normal operation, the main steam system transfers the high temperature and pressure steam generated from the steam generator in the nuclear power plant. Once there is an accident situation delivering the main steam isolation valve fast close signal or an unexpected main steam isolation valve close signal, the steam hammer phenomenon will be induced in the main steam system by the main steam isolation valve fast close incident. The steam hammer phenomenon might induce pressure rise rapidly in the main steam system and generate unintended transient load on the main steam system which might have effect on the safety operation of the nuclear power plant. Therefore the steam hammer phenomenon in the main steam system should be studied. The study creates the main steam system model which includes the main steam pipes, devices and connected system based on PIPENET software following the engineering data by a third generation nuclear power plant. The study takes the advantage of the transient mode in PIPENET to simulate the steam hammer phenomenon in the main steam system. The study simulates different boundary conditions and device parameters in order to analyze the different effects on the steam hammer phenomenon in the main steam system. The simulation model could calculate the pressure, load and other parameters in the main steam system during the main steam isolation valve fast close period. The effects of the steam hammer phenomenon could be analyzed through these characteristic parameters. The PIPENET model could simulate the main steam system action during the main system isolation valve fast close incident which helps the study to master the operation and function of the main steam system and verify the integrality of the main steam system in the steam hammer phenomenon. With the simulation and analysis of the steam hammer phenomenon in the main steam system simulated in the PIPENET, the pressure raise which induced by the steam hammer wouldn’t threat the integrality of the main steam system. And the main steam system could ensure the safety operation by steam discharge through the steam dump valves and main steam safety valves.