In introduction to the role of nuclear physics in the analysis of accelerator neutrino oscillations experiments is presented in the context of the theoretical possibility of extracting neutrino energies using the charge-changing neutrino reaction on deuterium in heavy water. In a recently published paper on this topic we showed that it is theoretically possible to separate the deuterium and oxygen contributions to the semi-inclusive cross sections for heavy water.  If an appropriate detector could be constructed this would allow for real time measurement of the neutrino flux or for extension of earlier bubble chamber experiments with liquid deuterium to measure axial form factor at higher values of $Q^2$.