  Beryllium reflectors are used at spallation neutron sources in order to
enhance the low-energy flux of neutrons emanating from the surface of a cold
and thermal moderator. The design of such a moderator/reflector system is
typically carried out using detailed Monte-Carlo simulations, where the
beryllium reflector is assumed to behave as a poly-crystalline material. In
reality, however, inhomogeneities in the beryllium could lead to discrepancies
between the performance of the actual system when compared to the modeled
system. The dependence of the total cross section in particular on crystallite
size, in the Bragg scattering region, could influence the reflector
performance, and if such effect is significant, it should be taken into account
in the design of the moderator/reflector system. In this paper, we report on
the preliminary results of using cross-section libraries, which include
corrections for the crystallite size effect, in spallation source neutronics
calculations.
