Discovering the causes for the change of the vibration characteristics of the core support barrel in PWR nuclear power plants: A combined investigation based on ex-core neutron noise analysis and numerical modal analysis

Jiaxin Liu, Deping Yu, Taibo Yang, Caixue Liu, Guangjin Wang, Xiaoming Liu

Abstract: Highlights•·The vibration frequency of the core support barrel (CSB) of pressurized water reactor (PWR) nuclear power plants was found to drop during the operation of the reactor.•·Numerical model of the PWR reactor internals was proposed with consideration of the frictional contact and fluid-structure interaction for the modal analysis of the CSB.•·The drop of the vibration frequency of the CSB was found to be caused by the stiffness degradation of the fuel assembly hold-down spring (FAHDS).