A STUDY OF MECHANICALLY INDUCED VIBRATION LOADS ON THE REACTOR COOLANT PUMP OF A SMALL MODULAR REACTOR

Ensuring the structural integrity of reactor internals in Small Modular Reactors (SMRs) is crucial, particularly regarding vibrations induced by Reactor Coolant Pumps (RCPs). Unlike conventional large reactors, SMRs often integrate RCPs in the upper reactor vessel, as seen in Korea's System-integrated Modular Advanced ReacTor(SMART) and innovative SMR(i-SMR) designs. This configuration presents unique challenges, as mechanically induced vibration (MIV) loads from the RCPs significantly impact reactor internals. Especially, MIV loads are usually quantified through lab tests because conducting shop tests on real SMRs is costly. However, the accuracy of the results cannot be fully guaranteed due to discrepancies in structural features between the experimental setup and real SMRs. To address these challenges, this study applies the ISO 20270 standard, which provides guidelines for quantifying the equivalent load transmitted from a source structure to the interfaces of receiver structures and is based on an in-situ methodology. This methodology enables more realistic load estimations under operational conditions and allows for the independent identification of MIV loads from individual components. These features ensure accurate response estimation even when different receiver structures are used. In this study, we employ this technique to quantify the MIV loads at the interface points of RCPs in lab test, ensuring valid response estimations. Through experimental validation, we demonstrate the accuracy and reliability of this approach. Furthermore, it can be applied to assess the vibration behavior of SMR reactor internals under the U. S. Nuclear Regulatory Commission (NRC) guidelines.