Theoretical and experimental study of auxiliary pump during faulted condition accident

A seismic qualification program of a low head safety injection pump is presented under the following two complementary aspects: 1. Analytical study of pump and seismic behaviour calculation. Pump is modelized using the finite element method. Study emphasizes the shaft vibratory behaviour in normal and faulted conditions. Owing to the bearing nonlinearities, the presence of fluid and gyroscopic effects, a transient nonlinear dynamic analysis is performed. In order to establish a finite element calculation methodology, specific assumptions must be defined for the following items: - fluid effects on pump shaft behaviour (stiffness and damping matrices, added masses) - stiffness and damping laws of fluid bearings - action of static and dynamic forces on pump shaft - gyroscopic effect. 2. Full size seismic tests are next presented. The pump has been set on a biaxial shaker table at CEA/SACLAY: two seismic movements (horizontal and vertical) were simulated. It was operated and hydraulic parameters (flow-head) have been changed during tests. Static loads were applied on suction and discharge nozzles during tests to simulate envelope loads applied by pipes in various conditions. Three levels of loads corresponding to normal, upset and faulted conditions have been provided. In addition to accelerometers and strain gages set on the pump body and its support, several deflection monitoring devices have been located inside the pump casing in order to determine the shaft vibratory behaviour. Tests of various types have been performed: - operating tests - natural frequencies search (horizontal and vertical) - seismic tests (three levels of excitation have been provided). Tests have been performed successively along the two main horizontal directions of pump. This experimentation complements informations on vibratory phenomena of pump in normal and faulted conditions. (orig./HP)