  In this paper, we consider the inverse problem of state estimation of nuclear
power fields in a power plant from a limited number of observations of the
neutron flux. For this, we use the Parametrized Background Data Weak approach.
The method combines the observations with a parametrized PDE model for the
behavior of the neutron flux. Since, in general, even the most sophisticated
models cannot perfectly capture reality, an inevitable model error is made. We
investigate the impact of the model error in the power reconstruction when we
use a diffusion model for the neutron flux, and assume that the true physics
are governed by a neutron transport model.
