Pump-induced fluctuating pressure in a reactor coolant pipe

An analytical model is proposed to describe the propagation of pressure pulsations originated at the pump outlet through the inlet pipe of a pressurised water reactor (PWR). Pressure pulsations data from a pre-critical vibration monitoring programme (PVMP) for a C-E reactor are presented and compared with those calculated by the analytical model, which essentially consists of a one-dimensional wave equation with time-dependent non-homogeneous boundary conditions. Closed-form solutions for the problem are derived using a linear transformation technique which reduces the problem to one involving a non-homogeneous differential equation with homogeneous boundary conditions. Numerical examples are given for a typical reactor. Pressure spectral density data are presented for data taken at inlet nozzles during a C-E PVMP. The spatial distributions of the pressure field along the length of the inlet pipe for the three typical boundary conditions are given. Finally, the effect of the pipe geometry on the pressure field and the acoustic frequencies is analysed. (author)