  It has been suggested that a potentially large fraction of supernovae could
be accompanied by relativistic outflows that stall below the stellar surface.
In this letter we point out that internal shocks that are believed to
accelerate protons to very high energies in these flows will also accelerate
secondary mesons and muons. As a result the neutrino spectrum from meson and
muon decay is expected to be much harder compared to previous estimates,
extending as a single power law up to ~10^3 TeV. This greatly improves the
detection prospects.
