Relaxation Characteristics of Hold-Down Spring of Core Support Barrel in Nuclear Reactor

Abstract

The stability of the core support barrel (CSB) in a nuclear reactor is the guarantee and premise for the normal operation of the reactor core. As the constraint and support of the CSB, the hold-down spring (HDS) directly affects the vibration characteristics of the CSB. Under harsh conditions such as high temperature and radiation, degradation such as stress relaxation may occur in terms of the performance of the HDS, which will affect the vibration of the CSB and the operation security of the reactor. Therefore, it is necessary to study the relaxation characteristics of the HDS of the CSB. First, a finite element model including the CSB and the HDS is established. The wet modal method is adapted to analyze and obtain the change of the beam mode frequency of the CSB with the relaxation degradation of the HDS. Then, a relaxation test of the HDS of the CSB is conducted to verify the simulation results. The simulation model is further used to generate more beam mode frequency data of the CSB under the impact of different relaxation degrees of the HDS. Finally, combined with simulation and test data, a mathematical model for identifying the relaxation degree of the HDS of the CSB is established, which lays a technical foundation for monitoring the relaxation and degradation of the HDS of the CSB in nuclear reactor.

Keywords

• core support barrel (csb)
• hold-down spring (hds)
• relaxation characteristics
• modal analysis
• relaxation test