Photon Buildup Factors in Laminated Dual-Layer Shields

Abstract

In radiation protection, photon buildup factors provide a convenient method for calculating dose and exposure response after various shielding configurations, as well as information about the behavior of radiation in these configurations. Though many situations call for multi-layer shields, few data bases and derived analytical formulas for photon buildup in multi-layer shields exist. This research develops buildup factors and an analytical fit to these for dual-layer shields of various materials.The photon buildup factors were calculated for two-layer shields of various combinations of lead, polyethylene, aluminum and stainless steel for thicknesses of 2-20 mean free paths using the discrete-ordinates code PARTISN. The Gauss-Lobatto S100 quadrature was used with a 244-energy-group structure and coupled photon and electron cross sections. These were then benchmarked for representative cases using MCNP5 and fit to a new analytical formula using Mathematica 6.0.