TOWARDS THE VALIDATION OF NEUTRON NOISE SIMULATORS: QUALIFICATION OF DATA ACQUISITION SYSTEMS

This paper deals with the processes involved in the generation of reliable experimental
data for the validation of computer simulations. In the field of neutron noise, the analysis
of results is based on spectral features of the detector signals in the frequency domain.
Neutron noise simulators also produce estimates that are subjected to studies in the same
domain. The validation process of such simulations begins with the generation of reliable
experimental data. In this work, we analyze results from two neutron noise experimental
campaigns. The focus is placed upon de comparison of results obtained by different data
acquisition systems (DAQs) that were used to record the data in parallel. The goal is to
verify whether results obtained by the different DAQs are consistent, and thus reliable.
The neutron noise-dedicated experiments were carried out in the AKR-2 reactor at the
Technische Universität Dresden and in the CROCUS reactor at the École polytechnique
fédérale de Lausanne. The experiments consisted in introducing different types of periodic
reactivity perturbations: a rotating neutron absorber with a varying absorption crosssection
with respect to the rotation angle; a linearly vibrating absorber that is moved back
and forth inside the reactor core; and a fuel rods oscillator that allows to vibrate a set of
fuel rods.