Neutron noise simulations in a heterogeneous system: A comparison between a diffusion-based and a discrete ordinates solver.

A comparative study on two neutron noise solvers is presented. The first solver is the simulator
CORE SIM which is based on neutron diffusion theory, while the second one makes use of a
discrete ordinates method. For the comparison, a two-dimensional, heterogeneous critical
system with a localized perturbation, is considered. The perturbation is defined as a fluctuation
of the macroscopic neutron capture cross-section in one point of the system. Differences can
be found between the two solvers because of the heterogeneities of the system and the
perturbation.