BWR Recirculation Pump Adjustable Speed Drive Performance and Control Affects

Exelon Nuclear has recently installed adjustable speed drives (ASD), or variable frequency drives (VFD), in place of the original motor-generator (MG) sets for their boiling water reactor (BWR) recirculation pumps at Quad Cities. This paper reviews expected versus actual performance of the drives and motors. The discussion focuses on energy savings, motor starting characteristics, control accuracy and stability, motor and cable thermal behavior; as well as, a comparison of actual supply system input harmonic measurements versus analysis results. Included in the review are a few operational lessons learned with regard to the startup process, input medium voltage low speed holds, loss of cooling water pump suction pressure, cooling system surge tank level indication, and other miscellaneous points of interest.