  We study the role of light neutron-rich nuclei during r-process
nucleosynthesis in supernovae. Most previous studies of the r-process have
concentrated on the reaction flow of heavy unstable nuclei. Although the
nuclear reaction network includes a few thousand heavy nuclei, only limited
reaction flow through light-mass nuclei near the stability line has been used
in those studies. However, in a viable scenario of the r-process in
neutrino-driven winds, the initial condition is a high-entropy hot plasma
consisting of neutrons, protons, and electron-positron pairs experiencing an
intense flux of neutrinos. In such environments light-mass nuclei as well as
heavy nuclei are expected to play important roles in the production of seed
nuclei and r-process elements. Thus, we have extended our fully implicit
nuclear reaction network so that it includes all nuclei up to the neutron drip
line for Z $ \leq 10$, in addition to a larger network for Z $ \geq 10$. In the
present nucleosynthesis study, we utilize a wind model of massive SNeII
explosions to study the effects of this extended network. We find that a new
nuclear-reaction flow path opens in the very light neutron-rich region. This
new nuclear reaction flow can change the final heavy-element abundances by as
much as an order of magnitude.
