Effect of Lead Sandwiched Between Concrete Layers on Neutron Production

Determine the effect of sandwiching a lead layer between two concrete layers on the neutron production rate in high-energy medical linear accelerator bunkers, and quantify whether this configuration increases, decreases, or leaves unchanged the neutron production rate compared with configurations where lead is placed in front of or behind concrete walls.

Background

This study used MCNPX simulations of an Elekta Infinity 18 MV linear accelerator to evaluate neutron and photon fluence and equivalent neutron dose for various shielding configurations, including heterogeneous concrete arrangements and the inclusion of metal layers. The results showed that sandwiching steel between concrete layers reduces neutron dose, while placing metal barriers in front of or behind concrete increases photoneutron production.

Despite evaluating lead and steel in several placements, the authors report that the specific impact of sandwiching a lead layer between two concrete layers on neutron production remains unresolved. Clarifying this effect is important for optimizing bunker shielding designs that balance radiation safety and construction constraints.