Research On The Crushing Characteristics Of Particle Material Of Fusion Reactor Pebble Bed Based On Discrete Element Method

The tritium breeder blanket is one of the core components of the fusion reactor device.One of its main functions is the tritium breeding and extracting,and to achieve tritium self-sustainment as much as possible.The tritium breeder blanket adopts the form of a pebble bed to contain and accumulate particles,and the environment of the fusion reactor where the pebble bed is located is extremely harsh,so some particles may be broken due to the influence of multiple complex loads.Therefore,it is very important to study the crushing behavior of particles and the influence of particle crushing on the performance of the pebble bed.The main contents of the paper are as follows:1.Based on the particle crushing criterion and particle crushing form,a method to simulate the particle crushing of the pebble bed was proposed to investigate the crushing behavior of the breeder blanket pebble bed under uniaxial compression.The changes of axial local packing factor and radial local packing factor of the breeder blanket pebble bed under two different pebble bed strains were studied,and the influence of pebble bed strain on the particle coordination number was obtained.The results show that the pebble bed stress and the contact force between particles do not change obviously when the pebble bed strain is relatively small,and change significantly with the gradual increase of the pebble bed strain.The wall effect exists in both axial local packing factor and radial local packing factor under different pebble bed strains.The overall distribution of coordination number of pebble bed particles presents a Gaussian distribution under different pebble bed strains.2.The discrete element software LIGGGHTS-PUBLIC was used to simulate the uniaxial compression test of the breeder blanket pebble bed with different crushing ratios to study the compression performance of the pebble bed.The influences of the coefficient of restitution and the coefficient of friction on the overall strength of the pebble bed were investigated,and the influence of different pebble bed strains and pebble bed crushing ratios on the average contact force,average packing fraction,average coordination number and contact force chain of the pebble bed were obtained.The results show that under the same pebble bed strain,the pebble bed stress decreases with the increase of broken particles.The crushing ratio,the coefficient of restitution and the coefficient of friction affect the overall strength of the pebble bed together.When the overall strain of the pebble bed is small,the average packing fraction of the pebble bed increases linearly with the increase of the strain of the pebble bed.The average coordination number of the pebble bed increases with the increase of the strain of the pebble bed,and decreases with the increase of the crushing ratio of the pebble bed.The number of strong force chains of the pebble bed increases with the increase of the strain of the pebble bed,and decreases with the increase of the crushing ratio of the pebble bed.The research carried out in this paper provides an important reference for the further study of the impact of broken particles on the mechanical performance of the breeder blanket pebble bed.Figure[40]Table[7]Ref[81].