  We present here an extended nuclear network, with 90 species, designed for
being coupled with hydrodynamic simulations, which includes neutrons, protons,
electrons, positrons, and the corresponding neutrino and anti-neutrino
emission. This network is also coupled with temperature, making it extremely
robust and, together with its size, unique of its kind. The inclusion of
electron captures on free protons makes the network very appropriate for
multidimensional studies of Type Ia supernova explosions, especially when the
exploding object is a massive white dwarf.
  The results obtained with the proposed medium-sized network compare fairly
well, to a few percent, with those computed with the extended network WinNet (>
2000 isotopes) in scenarios reproducing the gross physical conditions of
current Type Ia supernova explosion models. In those cases where the carbon and
oxygen fuel ignites at high density, the high-temperature plateau typical of
the nuclear statistical equilibrium regime is well defined and stable, allowing
large integration time steps. We show that the inclusion of electron captures
on free protons substantially improves the estimation of the electron fraction
of the mixture. Therefore, the pressure is better determined than in networks
where electron captures are excluded, which will ultimately lead to more
reliable hydrodynamic models. Explosive combustion of helium at low density,
occurring near the surface layer of a white dwarf, is also better described
with the proposed network, which gives nuclear energy generation rates much
closer to WinNet than typical reduced alpha networks.
