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 peri- odic reactivity perturbations: a rotating neutron absorber with a varying absorption cross- section 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.