  We report on measurements of thermal neutron fluxes at different locations in
the STAR experimental hall during pp $\sqrt s$ = 510 GeV Run 13 at RHIC. We
compared these measurements with calculations based on \textsc{PYTHIA} as
minimum bias events generator, the detailed GEANT3 simulation of the STAR
detector and the experimental hall, and using GCALOR as neutron transport code.
A good (within $\approx$ 30%) agreement was found at locations near
($\approx$1m) and very far ($\approx$10m) from the beam pipe. For intermediate
locations ($\approx$ 5m) the simulation overestimates neutron flux by a factor
of $\approx$3.
