  We calculate the diffuse intensity of cosmic ray (CR) nuclei and their
secondaries in the Boron-Carbon group produced by supernova remnants (SNR). The
trajectories of charged particles in the SNR are modeled as a random walk in
the test particle approximation. Secondary production by CRs colliding with gas
in the SNR is included as a Monte Carlo process, while we use Galprop to
account for the propagation and interactions of CRs in the Galaxy. In the
vicinity of a source, we find an approximately constant B/C ratio as a function
of energy. As a result, the B/C ratio at Earth does not rise with energy, but
flattens instead in the high energy limit. This prediction can be soon tested
by the AMS-2 collaboration.
