Determination of Loss of Coolant Accident (LOCA) in Nuclear Power Plants Using Signal Processing Method

A major objective in reactor design is to provide the capability to withstand a wide range of postulated events without exceeding specified safety limits. Assessment of the consequence of hypothetical Loss of Coolant Accident (LOCA) in primary circuit is an essential element to address fulfillment of acceptance criteria. In addition to analysis of behavior of plants during a LOCA, finding the position of rupture help to manage accident in a right direction. In this work, the transient vibration signal from a pipe rupture is used to determine the position of LOCA. A finite element formulation (Galerkin Method) is implemented to include the effect of fluid-structure interaction (FSI). The coupled equations of fluid motion and pipe displacement are solved. The results are in good agreement with published data.Fast Fourier Transform (FFT) provides an alternate way of representing data: instead of representing the vibration signal amplitude as a function of time, we represent this signal by how much information is contained at different frequencies. The most of the frequencies of the structure and the fluid coupled are present in the FFT of structural response and then the dominant frequency of excitation is obtained.In addition, the Power Spectral Density (PSD), a measurement of energy at various frequencies is worked out. To convert signals from the time domain to the frequency domain and to obtain PSD of those signals, this analysis was performed using MATLAB software.