  The observation of X-rays during quiescence from transiently accreting
neutron stars provides unique clues about the nature of dense matter. This,
however, requires extensive modeling of the crusts and matching the results to
observations. The pycnonuclear fusion reaction rates implemented in these
models are theoretically calculated by extending phenomenological expressions
and have large uncertainties spanning many orders of magnitude. We present the
first sensitivity studies of these pycnonuclear fusion reactions in realistic
network calculations. We also couple the reaction network with the thermal
evolution code dStar to further study their impact on the neutron star cooling
curves in quiescence. Varying the pycnonuclear fusion reaction rates alters the
depth at which nuclear heat is deposited although the total heating remains
constant. The enhancement of the pycnonuclear fusion reaction rates leads to an
overall shallower deposition of nuclear heat. The impurity factors are also
altered depending on the type of ashes deposited on the crust. These total
changes correspond to a variation of up to 9 eV in the modeled cooling curves.
While this is not sufficient to explain the shallow heat source, it is
comparable to the observational uncertainties and can still be important for
modeling the neutron star crust.
