Reflector Modelization for Neutronic Diffusion and Parameters Identification

Abstract

Description of neutrons in a nuclear core uses diffusion equations that need some physical parameters. In-core real measurements can be used to adjust these parameters by an identification procedure. to decrease calculations-measurements errors. Because the reflector is always difficult to modelize, we choose to elaborate a new reflector model and to use parameters of this model as adjustement coefficients. For nuclear core diffusion calculations, the reflector can be replaced by boundary conditions for the diffusion equations on the core only. This theoretical result of non- local operator relations leads then to some discrete approximations by taking into account the multiscaled behaviour, on the core-reflector interface, of neutronic diffusion solutions. The resulting model of this approach is then compared with previous reflector modelizations, and first results indicate that this new model give the same representation of reflector for the core than previous ones. Parameters identification have still to be tested out.