  10 years from now reactor neutrino experiments will attempt to determine
which neutrino mass eigenstate is the most massive. In this letter we present
the results of more than seven million detailed simulations of such
experiments, studying the dependence of the probability of successfully
determining the mass hierarchy upon the analysis method, the neutrino mass
matrix parameters, reactor flux models, geoneutrinos and, in particular,
combinations of baselines. We show that a recently reported spurious dependence
of the data analysis upon the high energy tail of the reactor spectrum can be
removed by using a weighted Fourier transform. We determine the optimal
baselines and corresponding detector locations. For most values of the
CP-violating, leptonic Dirac phase delta, a degeneracy prevents NOvA and T2K
from determining either delta or the hierarchy. We determine the confidence
with which a reactor experiment can determine the hierarchy, breaking the
degeneracy.
