  Strongly-interacting dark matter can be accumulated in large quantities
inside the Earth, and for dark matter particles in a few GeV mass range, it can
exist in large quantities near the Earth's surface. We investigate the
constraints imposed on such dark matter properties by its upscattering by fast
neutrons in nuclear reactors with subsequent scattering in nearby well-shielded
dark matter detectors, schemes which are already used for searches of the
coherent reactor neutrino scattering. We find that the existing experiments
cover new parameter space on the spin-dependent interaction between dark matter
and the nucleon. Similar experiments performed with research reactors, and
lesser amount of shielding, may provide additional sensitivity to
strongly-interacting dark matter.
