  Understanding the transport of cosmic rays is challenging our models of
propagation in the Galaxy. A good characterization of the secondary cosmic rays
(B, Be, Li and sub-iron species) is crucial to constrain these models and
exploit the precision of modern CR experiments. In this work, a Markov chain
Monte Carlo analysis has been implemented to fit the experimental flux ratios
between B, Be and Li and their flux ratios to the primary cosmic-ray nuclei C
and O. We have fitted the data using two different parametrizations for the
spallation cross sections. The uncertainties in the evaluation of the spectra
of these secondary cosmic rays, due to spallation cross sections, have been
taken into account introducing a scale factor as a nuisance parameter in the
fits, assuming that this uncertainty is mostly due to the normalization of the
cross sections parametrizations. We have also tested two different kind of
diffusion coefficients, which differ in the origin of the high energy hardening
($\sim 200$ GeV/n) of cosmic rays. Additionally, two different approaches are
used to scale the cross sections, one based on a combined analysis of all the
species ("combined" analysis) and the other reproducing the high energy spectra
of the secondary-to-secondary flux ratios of Be/B, Li/B, Li/Be ("corrected"
analysis). This allows us to make a better comparison between the propagation
parameters inferred from both cross sections parametrizations. This novel
analysis has been successfully implemented using the numerical code DRAGON2
dedicated to cosmic-ray propagation to reproduce the cosmic-ray nuclei data up
to $Z=14$ from the AMS-02 experiment. We report the main results, comparing the
different cross sections parametrizations and discussing the impact of these
uncertainties.
