  Nuclear structure functions at small x and small or moderate $Q^2$ are
studied using the relation with diffraction on nucleons which arises from
Gribov's Reggeon Calculus. A reasonable description of experimental data is
obtained with no fitted parameters. A comparison with other models and
predictions for future lepton-ion colliders are provided. Consequences for the
reduction of multiplicities in nucleus-nucleus collisions at energies of RHIC
and LHC are examined.
