  We study the impact of nonlinear bulk viscosity due to Urca reactions driven
by tidally-induced fluid motion during binary neutron star inspiral. Fluid
compression is computed for low radial order oscillation modes through an
adiabatic, time-dependent solution of the mode amplitudes. Optically thin
neutrino emission and heating rates are then computed from this adiabatic fluid
motion. Calculations use direct and modified Urca reactions operating in a
$M=1.4\, M_\odot$ neutron star, which is constructed using the Skyrme Rs
equation of state. We find that the energy pumped into low order oscillation
modes is not efficiently thermalized even by direct Urca reactions, with core
temperatures reaching only $T \simeq 10^8\, {\rm K}$ during the inspiral.
Although this is an order of magnitude larger than the heating due to shear
viscosity considered by previous studies, it reinforces the result that the
stars are quite cold at merger. Upon excitation of the lowest order g-mode, the
chemical potential imbalance reaches $\beta > 1\, {\rm MeV}$ at orbital
frequencies $\nu_{\rm orb} > 200\, {\rm Hz}$, implying significant
charged-current optical depths and Fermi blocking. To asses the importance of
neutrino degeneracy effects, the neutrino transfer equation is solved in the
static approximation for the three-dimensional density distribution, and the
reaction rates are then computed including Fermi-blocking. We find that the
heating rate is suppressed by factors of a few for $\nu_{\rm orb} > 200\, {\rm
Hz}$. The spectrum of emitted $\nu_e$ and $\bar{\nu}_e$, including radiation
transfer effects, is presented for a range of orbital separations.
