Analysis on transient piping pressure and force caused by high pressure steam flow disturbances

This paper presents a quantitative analysis on transient responses of pressure and its resulting force to sudden operation of a pressure relief valve on the main steam line of a pressurized water reactor plant, which is initially in a closed system at high pressure. When the valve at closed position changes to the full open position suddenly, the shock can be generated by the sudden steam flow which may reach critical velocity and then travel through the pipe line causing some damages to the piping system. The major characteristics of shock are quantitatively investigated on the basis of one dimensional pressure wave theory. Through the application to the actual transient incident occurred at the Kori unit 1 on 16 April 2005, it is found that the present approach is quite practical to predict the transient behavior of shocks caused by sudden operation of valves.