The Effect of an Air/Ground Interface on Fluence from a Plane Source of Neutrons in Homogeneous Air.

摘要

A numerical approximation of the multigroup diffusion equation was used to evaluate fluence from a plane source of neutrons in a homogeneous air environment with an air/ground interface. Data from the air/ground model were compared with data from an infinite homogeneous air model to determine the effect of the air/ground interface on the total neutron fluence in the air. This simple model indicates that the ground acts as a neutron sink for all 22neutron energy groups studied. Based on this result, a set of modifications to the AFIT Nuclear Survivability Code was recommended to extend the useful range of that code below seven km. (Author)