Study on the Influence of Reactor Core Structure on Reactor Natural Vibration Frequency

Abstract

When the reactor operates under normal conditions, it will produce a certain vibration with 100Hz as the fundamental frequency, and when this vibration coincides with the natural vibration frequency of the reactor core, it will cause resonance between the two. Therefore, in order to solve this problem, this paper proposes an adjustment method of the natural vibration frequency of the reactor core, which adjusts the length of the air gap by adding an air gap into the reactor core Position and quantity are three parameters to accurately control the natural vibration frequency of reactor core, so as to avoid the resonance frequency range. Through COMSOL finite element simulation, it is found that with the increase of reactor air gap length, the natural vibration frequency of reactor core basically decreases linearly, and the natural vibration frequency of high-order mode decreases faster; At the same time, with the increase of the number of air gaps in the core, the natural vibration frequency of the reactor core basically decreases linearly; Moreover, the air gap at the lower part of the reactor core has a greater impact on its natural vibration frequency, and the air gap at the upper part has a smaller impact. Therefore, when adjusting the natural frequency of the reactor core, the number or length of air gap at the lower part of the core can be increased. This study can provide numerical reference for reactor vibration reduction.