Evaluation of Vibration Characteristics for Reactor Coolant Pump Considering Fluid Flow Effect

Reactor coolant pump (RCP) is designed for the heat transfer of heat which is generated from reactor vessel to steam generators by circulating the coolant water. RCP is the only rotating equipment in the nuclear steam supply system (NSSS). Therefore, the problem of vibration has arisen caused by the hydraulic forces of the working fluid. These forces can drastically alter the critical speeds and stability characteristics and can act as significant destabilizing forces. So, vibration evaluation of RCP has been considered as a very important issue [1]. Among them, unbalance response caused by weight of unbalancing of rotating shaft could have serious effects on the entire rotor system. Thus, precise unbalance response spectrum analyses are required. In general, in order to evaluate the unbalance response characteristics for centrifugal pump, finite element analysis was performed according to the ISO 1940-1 standard. However, finite element analysis according to the ISO 1940-1 standard does not considering fluid flow effect. So, finite element analysis result and experimental results may be some differences. Vibration characteristics of RCP has affected by fluid flow effect induced from working fluid. Therefore, in order to understand vibration characteristics for the RCP shaft assembly considered in actual operating condition, rotor dynamic analysis should be performed considering the fluid flow effect. In this research, owing to accurately evaluate the vibration characteristics for the RCP considering hydro forces due to the fluid flow, we measured the bearing force and moment take into account the fluid-induced force. And then response spectrum analysis of RCP shaft assembly was performed considering fluid induced bearing radial forces which are measured values. Lastly, evaluate the vibration characteristics considering effect of fluid flow according to the number of revolution.