Benchmark results for the “BWR-PB” fuel assembly based on pebble-bed coated particles with uranium dioxide and gadolinia poison

Abstract

This paper presents an innovative concept for a long life, boiling water reactor with pebble-bed coated particles (BWR-PB), small nuclear reactor without open-vessel refuelling. Small nuclear reactors without the need for on-site refuelling have a greater simplicity, better compliance with passive safety systems and are more adequate for countries with small electric grids and limited investment capabilities. Besides, it will help the developing countries to develop their economy, but at the same time these reactors must not lead to the proliferation of a nuclear material, which could be used to fabricate weapons. This study contributes to the evaluation of some neutronic parameters with the aim of predicting both their static and dynamic behaviour before starting on concrete processes, an optimization of fuel assembly parameters for fuel cycle characteristics improvement and a possibility of assembly lifetime extension. In this work, all the parameters as well as infinite multiplication factor, spectrum index, neutron spectra and instantaneous conversion ratio were calculated for the fuel assembly with gadolinia poison and without any poison. The evaluation of this parameters shows that the fuel assembly life time can be extended for a reasonably period without outside refuelling. So, the aim of BWR-PB concept was verified.