Effect of Radial Neutron Reflector on the Characteristics of Nuclear Fuel Burn-up Wave in a Fast Neutron Energy Spectrum Multiplying Medium: A Consistent Parametric Approach

Abstract

The influence of radial neutron reflector on the build-up and propagation of a nuclear fuel burn-up wave in a fast multiplying medium is investigated using a consistent parametric approach. Coupled multi-group neutron diffusion equations with burn-up evolution model are simulated on the two-dimensional cylindrical reactor geometry with azimuthal symmetry. Uranium-Plutonium transmutation model is considered, and the simulation is performed by using finite element multiphysics software package COMSOL. Transient characteristics of the burn-up wave are represented by two new parameters, namely, Transient Time (TT) and Transient Length (TL). TT and TL are defined as the time and distance required for the burn-up wave to attain its steady-state nature. Steady-state phases are characterized in terms of wave velocity, Full Width Half Maximum (FWHM), and 10% of Maximum (FW10M). A sensitivity study of steady-state and transient parameters is conducted for the different values of radial reflector thickness. The potential relevance of these characterization parameters on the development of optimal geometrical configuration of radial neutron reflector in B&B based reactor design is addressed based on the sensitivity study.