Assessment of the loads on a solid centre reflector of a Pebble Bed Reactor using DEM techniques

Distinct Element Method (DEM) techniques are commonly used in the simulation of geotechnical problems. These techniques simulate a system of particles by explicitly modelling the particles and the interaction between these particles.A new application of these techniques is the simulation of the motion of fuel elements and the interaction of the fuel elements and the reflector structures in a Pebble Bed Reactor (PBR).The Pebble Bed Modular Reactor (PBMR) is a High Temperature Gas Cooled Reactor that is being designed (and soon to be constructed) in South Africa. This reactor makes use of a solid centre reflector. It is important to illustrate the effect of the pebble bed on the loading of this reflector to show that the reflector will be able to perform its required functions with sufficient reliability.This paper concerns the application of a DEM technique to the assessment of the loads that are experienced by the centre reflector of the 400 MWth (thermal) PBMR core as well as the assessment of the reliability of the centre reflector when subject to this loading.