Failure analysis of a primary reactor cooling pump using modal and vibration analysis

Four pumps redundantly supply primary cooling water to the reactor of the High Flux Isotope Reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). All four pumps underwent maintenance during a recently scheduled downtime. During preliminary evaluation following maintenance, one pump, PU-1A, exhibited higher vibration levels compared to the other three pumps. The pump, being a safety class item, underwent further performance testing to rule out potential damage resulting from the higher vibration. Vibration analysis and modal analysis including steady state spectrum, operational deflection shape, run up transients, and modal impact have been utilized to identify dynamic characteristics that could contribute to the increased vibration levels. This report will cover the testing setup, methodology, analysis results, and recommendations.