  The huge neutrino pulse that occurs during the collapse of a massive stellar
core, is expected to contribute to the origination of a number of isotopes both
of light chemical elements and heavy ones. It is shown that, in general, the
heating of stellar matter due to the neutrino scattering off electrons and the
heat released from the neutrino-helium breakup followed by the thermonuclear
reactions should be taken into account. On the base of kinetic network, using
all the important reactions up to Z=8, the main features and the time-dependent
character of the neutrino- driven neutron flux are investigated. The
time-dependent densities of free neutrons produced in helium breakup, Y_n(t),
were used to calculate the r-process nucleosynthesis with another full kinetic
network for 3200 nuclides. It was found that in the case of metal-deficient
stars, Z < 0.01 Z(solar), the resulting density of free neutrons seems to be
high enough to drive the r-process efficiently under favorable conditions. But
it is impossible to obtain a sufficient amount of heavy nuclei in
neutrino-induced r-process in a helium shell at radii R > R_cr \approx 10^9 cm.
We speculate that to make the neutrino-induced r-process work efficiently in
the shell, one has to invoke nonstandard presupernova models in which helium
hopefully is closer to the collapsed core owing, for instance, to a large scale
mixing or/and rotation and magnetic fields. Apart from this exotic possibility,
the neutrino-induced nucleosynthesis in the helium shell is certainly not
strong enough to explain the observed solar r-process abundances.
