Experimental study and discrete element method analysis of impact of vibration on pebble packing

Abstract

To develop tritium breeding technology for fusion reactors, Korea actively participated in the ITER Test Blanket Module (TBM) program, focusing on the development of a ceramic breeder-type TBM. The challenge was to introduce pebbles into the TBM without causing any damage to them. This study conducted experiments and Discrete Element Method (DEM) analyses to optimize the pebble-filling process for breeding blanket development. Even when facing obstacles such as grooved shapes on the walls of the pebble-filled space, these grooves did not significantly reduce the packing ratio. Vibrating the pebbles proved essential to increase the pebble packing ratio. Both experiments and DEM analyses confirmed an increase in pebble packing when vibration is applied. The study also investigated the impact of the timing of vibration application. It is better to vibrate after the pebble injection is done during injection to increase the pebble packing ratio. This approach increases the pebble packing ratio, but it also makes additional empty space. Consequently, maintaining continuous vibration from the initiation to the completion of the injection process can increase the packing ratio without the need to repeat the injection process to fill the empty space.