A novel method for the design and selection of neutron-attenuating media

A new methodology for designing neutron shields and selecting moderators using sets of generalized metrics is presented. The metrics were derived from many MCNP®6.2 simulations. Neutron and photon statistics were tracked at the outer surface of a sphere for each of the materials in each simulation to derive neutron energy attenuation coefficients that can accurately track the exponential energy decrement of neutrons in media. Neutron penetration probabilities as well as a normalized measure of the number of collisions were also obtained as a measure of the number of neutrons that penetrate the media and the number of collisions the neutrons undergo, respectively. Finally, the penetrative photon generation probability and their average energy were also obtained, allowing for photon dose rate computations. Attempts at generalizing each of the derived metrics are also discussed, showing the limitations of such simplifications. The methodology allows more streamlined approaches for analyzing complex neutron attenuating media.