Experimental measurement of graphite wear in helium at elevated temperatures and the discrete element modelling of graphite dust production inside the Pebble Bed Modular Reactor

[摘要] ENGLISH ABSTRACT: Production of graphite dust inside the Pebble Bed Modular Reactor (PBMR)influences the reactor operation negatively. Graphite is used as a moderator in thereactor core and the formation and transportation of graphite dust away from thereactor core decreases the amount of moderator which in turn has a negativeimpact on the reactor operation. High levels of radioactive dust may alsocontaminate reactor components which may pose a health risk to maintenancepersonnel.In this study a pressure vessel was designed and used to measure the wear of agraphite pebble in helium at elevated temperatures. By means of a multi-linearregression analysis a proper mathematical function was established in order torelate graphite wear to certain tribological parameters. These parameters wereidentified through a literature study.Discrete Element Modelling (DEM) was used to simulate the gravitational flow ofgraphite pebbles through the reactor core. The experimentally determinedmathematical function was incorporated into the DEM simulation to estimate theannual mass of graphite dust to be produced by the PBMR pebble bed as a resultof pebble-pebble interaction and pebble-wall interaction during refuelling.

[发布机构] Stellenbosch University