Investigation of reflection properties of applied reflectors for thermal neutrons by considering the albedo and spectral shift

In this paper, thermal neutrons reflection coefficient has been measured experimentally for water, graphite, polyethylene, and lead reflectors at average incident angle 56∘ by using 241Am-Be neutron source (5.2 Ci) and BF3 detector. Based on obtaining experimental data from different thicknesses for four reflectors, the maximum saturation value of the thermal neutron albedo is for polyethylene reflector and the minimum value of spectral shift is for lead reflector. The best reflector is a compromise included both high albedo and low spectral shift which causes to increase the safety of reactor. The measured value for thermal neutron albedo is 0.95 ± 0.03 at about 8 cm reflector thickness. Also, there is suitable agreement achieved between the experimental values and simulation results by using MCNPX Monte Carlo code.