Quantification of mechanical-induced vibration loads on the reactor coolant pump of a small modular reactor

An experimental procedure for quantifying mechanical-induced vibration (MIV) loads generated by reactor coolant pumps (RCPs) in small modular reactors (SMRs) is presented in this study. Reliable identification of these loads is essential for ensuring the structural integrity of reactor internals, as required by U.S. Nuclear Regulatory Commission Regulatory Guide 1.20, Revision 4. Conventional methods often fail to reflect operating conditions, creating uncertainties in MIV load quantification. To overcome this limitation, a procedure based on ISO 20270 is implemented and experimentally validated using a hydraulic pump as a scaled representation of RCPs. ISO 20270, originally developed for vibration source characterization in mechanical engineering applications, is here applied to nuclear engineering for the first time, with a focus on its practical and technical applicability to SMR systems. In addition, this study addresses several methodological aspects that are not explicitly defined in ISO 20270. A signal-to-noise ratio (SNR) based receiver design procedure is proposed to ensure the reliability of measured vibration signals, and a truncated singular value decomposition (TSVD) approach is employed to stabilize the inverse calculation of ill conditioned frequency response functions (FRFs). Quantified MIV loads are shown to reconstruct structural responses with high accuracy. This validation demonstrates that the proposed procedure is applicable in nuclear engineering contexts and has the potential to strengthen vibration assessment programs for SMRs.