Study on the perturbation effect of the different vibration frequency and amplitude to the fusion pebble bed

Abstract

The solid blanket is the main choice of the fusion reactor using the structure of pebble beds with beryllium as neutron multiplier and lithium silicate or lithium titanate as tritium breeder. The packing factor of the pebble bed is essential to the TBR(tritium breeder ratio), so it is important to study the mechanical behavior of particle system under the different kinds of the perturbations. In this paper, based on the mechanical behavior of solid pebble bed, the dynamic behavior of single particle system and mixed particle system under the different perturbation are simulated and analyzed by the EDEM software. The results show that, the perturbation can cause the packing factor of the particle system to increase continuously. In order to study the different way of the perturbation, three different typical models have been constructed. For the sinusoidal perturbation under the same strain, the stress of particle system decreases gradually, but the stress variation in the contraction and expansion process are different. The relationship between stress and vibration frequency roughly obeys the exponential decay law, and the stress drops faster with more violent disturbance. Then we use the mathematical model for fitting the relevant formula, which is valuable reference for engineering design in the future.