STATIC ANALYSIS OF ABSORBER BALL DRIVE MECHANISM BASED ON FINITE ELEMENT METHOD

Abstract

Absorber Ball Shutdown System (ABSS) is the special safety system for the High Temperature Reactor Pebble-bed Modules (HTR-PM), which controls the reaction power and shuts down the reaction in nuclear reactor. The drive mechanism in ABSS is an important equipment to control the dropping of absorber balls. The working environments for ABSS are high temperature 150°C and high pressure helium for 7 MPa. The drive mechanism will drive the valve on the bottom of ball storage capacity to open by a drive rod when ABSS is put into operation, and then the absorber balls in storage capacity will drop into the channel inside reflector to help shut down the reactions in nuclear reactor. Therefore, the smooth operation of drive rod under high temperature and high pressure environments is essential to achieve the performance of drive mechanism in ABSS. Finite element method (FEM) was carried out to achieve static analysis of the deformation and stress in the drive rod under external load caused by the harsh environments with the software ANSYS. The numerical results showed that the relative deformation was less than the gap between different components of the drive rod, and the maximum stress in drive rod was within permission