  We present the results on the source spectrum function for primary nuclei in
galactic cosmic rays, where two distinct energy dependences are used for the
source spectra. We discuss the evolution of the goodness of fit to B/C data
with the propagation parameters and also show that the results are not much
affected by a different choice for the diffusion scheme. We apply the
constraints on the diffusion scheme as derived from stable nuclei to calculate
the propagation of beta-radioactive isotopes. The diffusion model is refined to
properly take into account the effect of a local bubble in the interstellar
medium. Our calculations are compared to existing data, which prefer the local
bubble description instead of the homogeneus scheme.
